Merge pull request #506 from bonk-dev/s5-date

Add support for reading/writing the legacy DATE (IEC date) datatype

.github/workflows/dotnet.yml

@@ -0,0 +1,134 @@
+# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json
+
+name: .NET
+
+on:
+  workflow_dispatch: # Allow running the workflow manually from the GitHub UI
+  push:
+    branches:
+      - 'main'       # Run the workflow when pushing to the main branch
+  pull_request:
+    branches:
+      - '*'          # Run the workflow for all pull requests
+  release:
+    types:
+      - published    # Run the workflow when a new GitHub release is published
+  
+env:
+  DOTNET_SKIP_FIRST_TIME_EXPERIENCE: 1
+  DOTNET_NOLOGO: true
+  NuGetDirectory: ${{ github.workspace}}/nuget
+
+defaults:
+  run:
+    shell: pwsh
+
+jobs:
+  create_nuget:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0 # Get all history to allow automatic versioning
+
+    - name: Install GitVersion
+      uses: gittools/actions/gitversion/setup@v0
+      with:
+        versionSpec: '6.x'
+        includePrerelease: true
+        preferLatestVersion: true
+    
+    - name: Determine Version
+      id:   gitversion
+      uses: gittools/actions/gitversion/execute@v0
+
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v3
+
+    - run: >
+        dotnet pack
+        --configuration Release
+        /p:AssemblyVersion=${{ steps.gitversion.outputs.assemblySemVer }}
+        /p:FileVersion=${{ steps.gitversion.outputs.assemblySemFileVer }}
+        /p:InformationalVersion=${{ steps.gitversion.outputs.informationalVersion }}
+        /p:PackageVersion=${{ steps.gitversion.outputs.semVer }}
+        --output ${{ env.NuGetDirectory }}
+
+    - uses: actions/upload-artifact@v3
+      with:
+        name: nuget
+        if-no-files-found: error
+        retention-days: 7
+        path: |
+          ${{ env.NuGetDirectory }}/*.nupkg
+          ${{ env.NuGetDirectory }}/*.snupkg
+
+  run_test:
+    name: test-${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    env:
+      configuration: Release
+      artifacts: ${{ github.workspace }}/artifacts
+    strategy:
+      matrix:
+        os: [windows-latest, ubuntu-20.04, macos-latest]
+      fail-fast: false
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install Snap7 Linux
+        if: ${{ matrix.os == 'ubuntu-20.04' }}
+        run: |
+          sudo add-apt-repository ppa:gijzelaar/snap7
+          sudo apt-get update
+          sudo apt-get install libsnap7-1 libsnap7-dev
+          
+      - name: Install Snap7 MacOs
+        if: ${{ matrix.os == 'macos-latest' }}
+        run: |
+          brew install snap7
+
+      - name: Setup Dotnet
+        uses: actions/setup-dotnet@v3
+        with:
+          dotnet-version: |
+            6.x
+            7.x
+          
+      - name: Nuget Cache
+        uses: actions/cache@v3
+        with:
+          path: ~/.nuget/packages
+          # Look to see if there is a cache hit for the corresponding requirements file
+          key: ${{ runner.os }}-nuget-${{ hashFiles('**/packages.lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-nuget
+        
+      - name: Test
+        run: dotnet test --nologo --verbosity normal --logger GitHubActions
+
+  deploy:
+    # Publish only when creating a GitHub Release
+    # https://docs.github.com/en/repositories/releasing-projects-on-github/managing-releases-in-a-repository
+    # You can update this logic if you want to manage releases differently
+    if: github.event_name == 'release'
+    runs-on: ubuntu-latest
+    needs: [ create_nuget, run_test ]
+    steps:
+      - uses: actions/download-artifact@v3
+        with:
+          name: nuget
+          path: ${{ env.NuGetDirectory }}
+
+      - name: Setup .NET Core
+        uses: actions/setup-dotnet@v3
+
+      # Publish all NuGet packages to NuGet.org
+      # Use --skip-duplicate to prevent errors if a package with the same version already exists.
+      # If you retry a failed workflow, already published packages will be skipped without error.
+      - name: Publish NuGet package
+        run: |
+          foreach($file in (Get-ChildItem "${{ env.NuGetDirectory }}" -Recurse -Include *.nupkg)) {
+              dotnet nuget push $file --api-key "${{ secrets.NUGET_APIKEY }}" --source https://api.nuget.org/v3/index.json --skip-duplicate
+          }

.nuget/NuGet.Config

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-  <solution>
-    <add key="disableSourceControlIntegration" value="true" />
-  </solution>
-</configuration>

.nuget/NuGet.targets

@@ -1,144 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-    <PropertyGroup>
-        <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">$(MSBuildProjectDirectory)\..\</SolutionDir>
-
-        <!-- Enable the restore command to run before builds -->
-        <RestorePackages Condition="  '$(RestorePackages)' == '' ">false</RestorePackages>
-
-        <!-- Property that enables building a package from a project -->
-        <BuildPackage Condition=" '$(BuildPackage)' == '' ">false</BuildPackage>
-
-        <!-- Determines if package restore consent is required to restore packages -->
-        <RequireRestoreConsent Condition=" '$(RequireRestoreConsent)' != 'false' ">true</RequireRestoreConsent>
-
-        <!-- Download NuGet.exe if it does not already exist -->
-        <DownloadNuGetExe Condition=" '$(DownloadNuGetExe)' == '' ">false</DownloadNuGetExe>
-    </PropertyGroup>
-
-    <ItemGroup Condition=" '$(PackageSources)' == '' ">
-        <!-- Package sources used to restore packages. By default, registered sources under %APPDATA%\NuGet\NuGet.Config will be used -->
-        <!-- The official NuGet package source (https://www.nuget.org/api/v2/) will be excluded if package sources are specified and it does not appear in the list -->
-        <!--
-            <PackageSource Include="https://www.nuget.org/api/v2/" />
-            <PackageSource Include="https://my-nuget-source/nuget/" />
-        -->
-    </ItemGroup>
-
-    <PropertyGroup Condition=" '$(OS)' == 'Windows_NT'">
-        <!-- Windows specific commands -->
-        <NuGetToolsPath>$([System.IO.Path]::Combine($(SolutionDir), ".nuget"))</NuGetToolsPath>
-    </PropertyGroup>
-
-    <PropertyGroup Condition=" '$(OS)' != 'Windows_NT'">
-        <!-- We need to launch nuget.exe with the mono command if we're not on windows -->
-        <NuGetToolsPath>$(SolutionDir).nuget</NuGetToolsPath>
-    </PropertyGroup>
-
-    <PropertyGroup>
-        <PackagesProjectConfig Condition=" '$(OS)' == 'Windows_NT'">$(MSBuildProjectDirectory)\packages.$(MSBuildProjectName.Replace(' ', '_')).config</PackagesProjectConfig>
-        <PackagesProjectConfig Condition=" '$(OS)' != 'Windows_NT'">$(MSBuildProjectDirectory)\packages.$(MSBuildProjectName).config</PackagesProjectConfig>
-    </PropertyGroup>
-
-    <PropertyGroup>
-      <PackagesConfig Condition="Exists('$(MSBuildProjectDirectory)\packages.config')">$(MSBuildProjectDirectory)\packages.config</PackagesConfig>
-      <PackagesConfig Condition="Exists('$(PackagesProjectConfig)')">$(PackagesProjectConfig)</PackagesConfig>
-    </PropertyGroup>
-    
-    <PropertyGroup>
-        <!-- NuGet command -->
-        <NuGetExePath Condition=" '$(NuGetExePath)' == '' ">$(NuGetToolsPath)\NuGet.exe</NuGetExePath>
-        <PackageSources Condition=" $(PackageSources) == '' ">@(PackageSource)</PackageSources>
-
-        <NuGetCommand Condition=" '$(OS)' == 'Windows_NT'">"$(NuGetExePath)"</NuGetCommand>
-        <NuGetCommand Condition=" '$(OS)' != 'Windows_NT' ">mono --runtime=v4.0.30319 "$(NuGetExePath)"</NuGetCommand>
-
-        <PackageOutputDir Condition="$(PackageOutputDir) == ''">$(TargetDir.Trim('\\'))</PackageOutputDir>
-
-        <RequireConsentSwitch Condition=" $(RequireRestoreConsent) == 'true' ">-RequireConsent</RequireConsentSwitch>
-        <NonInteractiveSwitch Condition=" '$(VisualStudioVersion)' != '' AND '$(OS)' == 'Windows_NT' ">-NonInteractive</NonInteractiveSwitch>
-
-        <PaddedSolutionDir Condition=" '$(OS)' == 'Windows_NT'">"$(SolutionDir) "</PaddedSolutionDir>
-        <PaddedSolutionDir Condition=" '$(OS)' != 'Windows_NT' ">"$(SolutionDir)"</PaddedSolutionDir>
-
-        <!-- Commands -->
-        <RestoreCommand>$(NuGetCommand) install "$(PackagesConfig)" -source "$(PackageSources)"  $(NonInteractiveSwitch) $(RequireConsentSwitch) -solutionDir $(PaddedSolutionDir)</RestoreCommand>
-        <BuildCommand>$(NuGetCommand) pack "$(ProjectPath)" -Properties "Configuration=$(Configuration);Platform=$(Platform)" $(NonInteractiveSwitch) -OutputDirectory "$(PackageOutputDir)" -symbols</BuildCommand>
-
-        <!-- We need to ensure packages are restored prior to assembly resolve -->
-        <BuildDependsOn Condition="$(RestorePackages) == 'true'">
-            RestorePackages;
-            $(BuildDependsOn);
-        </BuildDependsOn>
-
-        <!-- Make the build depend on restore packages -->
-        <BuildDependsOn Condition="$(BuildPackage) == 'true'">
-            $(BuildDependsOn);
-            BuildPackage;
-        </BuildDependsOn>
-    </PropertyGroup>
-
-    <Target Name="CheckPrerequisites">
-        <!-- Raise an error if we're unable to locate nuget.exe  -->
-        <Error Condition="'$(DownloadNuGetExe)' != 'true' AND !Exists('$(NuGetExePath)')" Text="Unable to locate '$(NuGetExePath)'" />
-        <!--
-        Take advantage of MsBuild's build dependency tracking to make sure that we only ever download nuget.exe once.
-        This effectively acts as a lock that makes sure that the download operation will only happen once and all
-        parallel builds will have to wait for it to complete.
-        -->
-        <MsBuild Targets="_DownloadNuGet" Projects="$(MSBuildThisFileFullPath)" Properties="Configuration=NOT_IMPORTANT;DownloadNuGetExe=$(DownloadNuGetExe)" />
-    </Target>
-
-    <Target Name="_DownloadNuGet">
-        <DownloadNuGet OutputFilename="$(NuGetExePath)" Condition=" '$(DownloadNuGetExe)' == 'true' AND !Exists('$(NuGetExePath)')" />
-    </Target>
-
-    <Target Name="RestorePackages" DependsOnTargets="CheckPrerequisites">        
-        <Exec Command="$(RestoreCommand)"
-              Condition="'$(OS)' != 'Windows_NT' And Exists('$(PackagesConfig)')" />
-
-        <Exec Command="$(RestoreCommand)"
-              LogStandardErrorAsError="true"
-              Condition="'$(OS)' == 'Windows_NT' And Exists('$(PackagesConfig)')" />
-    </Target>
-
-    <Target Name="BuildPackage" DependsOnTargets="CheckPrerequisites">
-        <Exec Command="$(BuildCommand)"
-              Condition=" '$(OS)' != 'Windows_NT' " />
-
-        <Exec Command="$(BuildCommand)"
-              LogStandardErrorAsError="true"
-              Condition=" '$(OS)' == 'Windows_NT' " />
-    </Target>
-
-    <UsingTask TaskName="DownloadNuGet" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">
-        <ParameterGroup>
-            <OutputFilename ParameterType="System.String" Required="true" />
-        </ParameterGroup>
-        <Task>
-            <Reference Include="System.Core" />
-            <Using Namespace="System" />
-            <Using Namespace="System.IO" />
-            <Using Namespace="System.Net" />
-            <Using Namespace="Microsoft.Build.Framework" />
-            <Using Namespace="Microsoft.Build.Utilities" />
-            <Code Type="Fragment" Language="cs">
-                <![CDATA[
-                try {
-                    OutputFilename = Path.GetFullPath(OutputFilename);
-
-                    Log.LogMessage("Downloading latest version of NuGet.exe...");
-                    WebClient webClient = new WebClient();
-                    webClient.DownloadFile("https://www.nuget.org/nuget.exe", OutputFilename);
-
-                    return true;
-                }
-                catch (Exception ex) {
-                    Log.LogErrorFromException(ex);
-                    return false;
-                }
-            ]]>
-            </Code>
-        </Task>
-    </UsingTask>
-</Project>

NuGetPack.bat

@@ -1,12 +0,0 @@
-@echo off
-set /p version="Version: "
-msbuild S7.Net\S7.Net.csproj /P:Configuration=Release
-rmdir /S /Q nuget-pack\lib
-xcopy S7.Net\bin\Release\S7.Net.dll nuget-pack\lib\net35\ /Y 
-xcopy S7.Net\bin\Release\S7.Net.xml nuget-pack\lib\net35\ /Y 
-xcopy S7.Net\bin\Release\S7.Net.dll nuget-pack\lib\net40\ /Y 
-xcopy S7.Net\bin\Release\S7.Net.xml nuget-pack\lib\net40\ /Y 
-xcopy S7.Net\bin\Release\S7.Net.dll nuget-pack\lib\net45\ /Y 
-xcopy S7.Net\bin\Release\S7.Net.xml nuget-pack\lib\net45\ /Y 
-.nuget\nuget pack nuget-pack\S7.Net.nuspec -Version %version%
-pause

README.md

@@ -12,18 +12,17 @@ to my request for committing code, I decided to pick up where he left off here o
 ## Documentation
 Check the Wiki and feel free to edit it: https://github.com/killnine/s7netplus/wiki
 
-S7.Net Plus has a [User Manual](https://github.com/killnine/s7netplus/blob/master/Documentation/Documentation.pdf), check it out.
-
 ## Supported PLC
 
 + Compatible S7 PLC (S7-200, S7-300, S7-400, S7-1200, S7-1500)
 
-## Target framework
-+ .NET Framework 3.5 or higher
-+ Universal Windows Application (.Net Core) - see S7.UniversalWindowsApp.sln
+## Supported frameworks
++ .NET Framework 4.5.2 and higher
++ .NET Standard 1.3 (.NET Core 1.0, UWP 10.0, Xamarin, ...)
++ .NET Standard 2.0 (.NET Core 2.0, .NET Framework 4.6.1)
 
 ## Compile
-You need at least Visual Studio 2015 (you can download the Community Edition for free).
+You need at least Visual Studio 2017 (you can download the Community Edition for free).
 
 ## Nuget
 
@@ -35,6 +34,5 @@ PM> Install-Package S7netplus
 
 ## Running the tests
 
-Unit tests use Snap7 server, so port 102 must be not in use.
-If you have Siemens Step7 installed, the service s7oiehsx64 is stopped when running unit tests.
-You have to restart the service manually if you need it.
+Unit tests use Snap7 server.
+On Windows, the DLL is included with the test project. On other platforms, Snap7 must be installed manually before running tests.

S7.Net.Core/Properties/AssemblyInfo.cs

@@ -1,29 +0,0 @@
-using System.Reflection;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-
-// General Information about an assembly is controlled through the following 
-// set of attributes. Change these attribute values to modify the information
-// associated with an assembly.
-[assembly: AssemblyTitle("S7.Net.Core")]
-[assembly: AssemblyDescription("")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("Microsoft")]
-[assembly: AssemblyProduct("S7.Net.Core")]
-[assembly: AssemblyCopyright("Copyright © Microsoft 2016")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-
-// Version information for an assembly consists of the following four values:
-//
-//      Major Version
-//      Minor Version 
-//      Build Number
-//      Revision
-//
-// You can specify all the values or you can default the Build and Revision Numbers 
-// by using the '*' as shown below:
-// [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]
-[assembly: ComVisible(false)]

S7.Net.Core/Properties/S7.Net.Core.rd.xml

@@ -1,33 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-    This file contains Runtime Directives, specifications about types your application accesses
-    through reflection and other dynamic code patterns. Runtime Directives are used to control the
-    .NET Native optimizer and ensure that it does not remove code accessed by your library. If your
-    library does not do any reflection, then you generally do not need to edit this file. However,
-    if your library reflects over types, especially types passed to it or derived from its types,
-    then you should write Runtime Directives.
-
-    The most common use of reflection in libraries is to discover information about types passed
-    to the library. Runtime Directives have three ways to express requirements on types passed to
-    your library.
-
-    1.  Parameter, GenericParameter, TypeParameter, TypeEnumerableParameter
-        Use these directives to reflect over types passed as a parameter.
-
-    2.  SubTypes
-        Use a SubTypes directive to reflect over types derived from another type.
-
-    3.  AttributeImplies
-        Use an AttributeImplies directive to indicate that your library needs to reflect over
-        types or methods decorated with an attribute.
-
-    For more information on writing Runtime Directives for libraries, please visit
-    http://go.microsoft.com/fwlink/?LinkID=391919
--->
-<Directives xmlns="http://schemas.microsoft.com/netfx/2013/01/metadata">
-  <Library Name="S7.Net.Core">
-
-  	<!-- add directives for your library here -->
-
-  </Library>
-</Directives>

S7.Net.Core/S7.Net.Core.csproj

@@ -1,176 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
-  <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{CBFF80E8-3D3D-4656-A27C-A65EA5774536}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>S7.Net.Core</RootNamespace>
-    <AssemblyName>S7.Net.Core</AssemblyName>
-    <DefaultLanguage>en-US</DefaultLanguage>
-    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
-    <TargetPlatformVersion>10.0.10586.0</TargetPlatformVersion>
-    <TargetPlatformMinVersion>10.0.10240.0</TargetPlatformMinVersion>
-    <MinimumVisualStudioVersion>14</MinimumVisualStudioVersion>
-    <FileAlignment>512</FileAlignment>
-    <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <PlatformTarget>ARM</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <PlatformTarget>ARM</PlatformTarget>
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
-    <PlatformTarget>x86</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <OutputPath>bin\x86\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>full</DebugType>
-    <PlatformTarget>x86</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x86'">
-    <PlatformTarget>x86</PlatformTarget>
-    <OutputPath>bin\x86\Release\</OutputPath>
-    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>pdbonly</DebugType>
-    <PlatformTarget>x86</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|ARM'">
-    <PlatformTarget>ARM</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <OutputPath>bin\ARM\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>full</DebugType>
-    <PlatformTarget>ARM</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|ARM'">
-    <PlatformTarget>ARM</PlatformTarget>
-    <OutputPath>bin\ARM\Release\</OutputPath>
-    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>pdbonly</DebugType>
-    <PlatformTarget>ARM</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x64'">
-    <PlatformTarget>x64</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <OutputPath>bin\x64\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>full</DebugType>
-    <PlatformTarget>x64</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
-    <PlatformTarget>x64</PlatformTarget>
-    <OutputPath>bin\x64\Release\</OutputPath>
-    <DefineConstants>TRACE;NETFX_CORE;WINDOWS_UWP</DefineConstants>
-    <Optimize>true</Optimize>
-    <NoWarn>;2008</NoWarn>
-    <DebugType>pdbonly</DebugType>
-    <PlatformTarget>x64</PlatformTarget>
-    <UseVSHostingProcess>false</UseVSHostingProcess>
-    <ErrorReport>prompt</ErrorReport>
-  </PropertyGroup>
-  <ItemGroup>
-    <!-- A reference to the entire .Net Framework and Windows SDK are automatically included -->
-    <None Include="project.json" />
-  </ItemGroup>
-  <ItemGroup>
-    <Compile Include="..\S7.Net\Conversion.cs">
-      <Link>Conversion.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Enums.cs">
-      <Link>Enums.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\PLC.cs">
-      <Link>PLC.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Boolean.cs">
-      <Link>Types\Boolean.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Byte.cs">
-      <Link>Types\Byte.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\ByteArray.cs">
-      <Link>Types\ByteArray.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Class.cs">
-      <Link>Types\Class.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Counter.cs">
-      <Link>Types\Counter.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\DataItem.cs">
-      <Link>Types\DataItem.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\DInt.cs">
-      <Link>Types\DInt.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Double.cs">
-      <Link>Types\Double.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\DWord.cs">
-      <Link>Types\DWord.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Int.cs">
-      <Link>Types\Int.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\String.cs">
-      <Link>Types\String.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Struct.cs">
-      <Link>Types\Struct.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Timer.cs">
-      <Link>Types\Timer.cs</Link>
-    </Compile>
-    <Compile Include="..\S7.Net\Types\Word.cs">
-      <Link>Types\Word.cs</Link>
-    </Compile>
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="SocketClient.cs" />
-    <EmbeddedResource Include="Properties\S7.Net.Core.rd.xml" />
-  </ItemGroup>
-  <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">
-    <VisualStudioVersion>14.0</VisualStudioVersion>
-  </PropertyGroup>
-  <Import Project="$(MSBuildExtensionsPath)\Microsoft\WindowsXaml\v$(VisualStudioVersion)\Microsoft.Windows.UI.Xaml.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
--->
-</Project>

S7.Net.Core/S7.Net.Core.nuget.props

@@ -1,21 +0,0 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup Condition=" '$(ExcludeRestorePackageImports)' != 'true' ">
-    <RestoreSuccess Condition=" '$(RestoreSuccess)' == '' ">True</RestoreSuccess>
-    <RestoreTool Condition=" '$(RestoreTool)' == '' ">NuGet</RestoreTool>
-    <ProjectAssetsFile Condition=" '$(ProjectAssetsFile)' == '' ">C:\Users\shade\Documents\GitHub\s7netplus\S7.Net.Core\project.lock.json</ProjectAssetsFile>
-    <NuGetPackageRoot Condition=" '$(NuGetPackageRoot)' == '' ">$(UserProfile)\.nuget\packages\</NuGetPackageRoot>
-    <NuGetPackageFolders Condition=" '$(NuGetPackageFolders)' == '' ">C:\Users\shade\.nuget\packages\</NuGetPackageFolders>
-    <NuGetProjectStyle Condition=" '$(NuGetProjectStyle)' == '' ">ProjectJson</NuGetProjectStyle>
-    <NuGetToolVersion Condition=" '$(NuGetToolVersion)' == '' ">4.3.1</NuGetToolVersion>
-  </PropertyGroup>
-  <PropertyGroup>
-    <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
-  </PropertyGroup>
-  <ImportGroup Condition=" '$(ExcludeRestorePackageImports)' != 'true' ">
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x86\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x86.props" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x86\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x86.props')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x64\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x64.props" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x64\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x64.props')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-arm\1.7.0\build\Microsoft.Net.Native.SharedLibrary-arm.props" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-arm\1.7.0\build\Microsoft.Net.Native.SharedLibrary-arm.props')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.compiler\1.7.0\build\Microsoft.Net.Native.Compiler.props" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.compiler\1.7.0\build\Microsoft.Net.Native.Compiler.props')" />
-  </ImportGroup>
-</Project>

S7.Net.Core/S7.Net.Core.nuget.targets

@@ -1,12 +0,0 @@
-<?xml version="1.0" encoding="utf-8" standalone="no"?>
-<Project ToolsVersion="14.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup>
-    <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
-  </PropertyGroup>
-  <ImportGroup Condition=" '$(ExcludeRestorePackageImports)' != 'true' ">
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x86\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x86.targets" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x86\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x86.targets')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x64\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x64.targets" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-x64\1.7.0\build\Microsoft.Net.Native.SharedLibrary-x64.targets')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-arm\1.7.0\build\Microsoft.Net.Native.SharedLibrary-arm.targets" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.sharedlibrary-arm\1.7.0\build\Microsoft.Net.Native.SharedLibrary-arm.targets')" />
-    <Import Project="$(NuGetPackageRoot)microsoft.net.native.compiler\1.7.0\build\Microsoft.Net.Native.Compiler.targets" Condition="Exists('$(NuGetPackageRoot)microsoft.net.native.compiler\1.7.0\build\Microsoft.Net.Native.Compiler.targets')" />
-  </ImportGroup>
-</Project>

S7.Net.Core/SocketClient.cs

@@ -1,481 +0,0 @@
-using System;
-using System.Net.Sockets;
-using System.Threading;
-using System.Net;
-
-namespace S7.Net
-{
-    /// <summary>
-    /// This class encapsulate System.Net.Sockets.Socket class of .Net core, so we can use the same methods of the standard Socket class inside the S7.Net sources.
-    /// </summary>
-    internal class Socket
-    {
-
-        public bool Connected
-        {
-            get
-            {
-                if (_socket == null)
-                    return false;
-
-                return _socket.Connected;
-            }
-        }
-
-        public SocketError LastSocketError { get; private set; }
-
-        public Socket(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType)
-        {
-            _socket = new System.Net.Sockets.Socket(addressFamily, socketType, protocolType);
-        }
-
-        public void Connect(IPEndPoint server)
-        {
-            if (Connected)
-                return;
-
-            LastSocketError = SocketError.NotConnected;
-
-            var socketEventArg = new SocketAsyncEventArgs();
-
-            socketEventArg.RemoteEndPoint = server;
-
-            var completedEvent = new EventHandler<SocketAsyncEventArgs>(delegate (object s, SocketAsyncEventArgs e)
-            {
-                LastSocketError = e.SocketError;
-                _clientDone.Set();
-            });
-
-            socketEventArg.Completed += completedEvent;
-
-            _clientDone.Reset();
-
-            LastSocketError = SocketError.TimedOut;
-
-            _socket.ConnectAsync(socketEventArg);
-
-            _clientDone.WaitOne(TIMEOUT_MILLISECONDS);
-
-            socketEventArg.Completed -= completedEvent;
-        }
-
-        public int Send(byte[] buffer, int size, SocketFlags socketFlag)
-        {
-            var response = 0;
-
-            if (_socket != null)
-            {
-                var socketEventArg = new SocketAsyncEventArgs();
-
-                socketEventArg.RemoteEndPoint = _socket.RemoteEndPoint;
-                socketEventArg.UserToken = null;
-
-                var completedEvent = new EventHandler<SocketAsyncEventArgs>(delegate (object s, SocketAsyncEventArgs e)
-                {
-                    LastSocketError = e.SocketError;
-
-                    if (e.SocketError == SocketError.Success)
-                        response = e.BytesTransferred;
-
-                    _clientDone.Set();
-                });
-
-                socketEventArg.Completed += completedEvent;
-
-                socketEventArg.SetBuffer(buffer, 0, size);
-
-                _clientDone.Reset();
-
-                LastSocketError = SocketError.TimedOut;
-
-                _socket.SendAsync(socketEventArg);
-
-                _clientDone.WaitOne(_sendTimeout);
-
-                socketEventArg.Completed -= completedEvent;
-            }
-            else
-            {
-                LastSocketError = SocketError.NotInitialized;
-            }
-
-            return response;
-        }
-
-        public int Receive(byte[] buffer, int size, SocketFlags socketFlag)
-        {
-            var response = 0;
-
-            if (_socket != null)
-            {
-                var socketEventArg = new SocketAsyncEventArgs();
-
-                socketEventArg.RemoteEndPoint = _socket.RemoteEndPoint;
-                socketEventArg.SetBuffer(buffer, 0, size);
-
-                var completedEvent = new EventHandler<SocketAsyncEventArgs>(delegate (object s, SocketAsyncEventArgs e)
-                {
-                    LastSocketError = e.SocketError;
-
-                    if (e.SocketError == SocketError.Success)
-                        response = e.BytesTransferred;
-
-                    _clientDone.Set();
-                });
-
-                socketEventArg.Completed += completedEvent;
-
-                _clientDone.Reset();
-
-                LastSocketError = SocketError.TimedOut;
-
-                _socket.ReceiveAsync(socketEventArg);
-
-                _clientDone.WaitOne(_receiveTimeout);
-
-                socketEventArg.Completed -= completedEvent;
-            }
-            else
-            {
-                LastSocketError = SocketError.NotInitialized;
-            }
-
-            return response;
-        }
-
-        public void Shutdown(SocketShutdown how)
-        {
-            _socket.Shutdown(how);
-        }
-
-        public void Close()
-        {
-            if (_socket != null)
-            {
-                _socket.Dispose();
-                _socket = null;
-            }
-        }
-
-        //
-        // Summary:
-        //     Sets the specified System.Net.Sockets.Socket option to the specified integer
-        //     value.
-        //
-        // Parameters:
-        //   optionLevel:
-        //     One of the System.Net.Sockets.SocketOptionLevel values.
-        //
-        //   optionName:
-        //     One of the System.Net.Sockets.SocketOptionName values.
-        //
-        //   optionValue:
-        //     A value of the option.
-        //
-        // Exceptions:
-        //   T:System.Net.Sockets.SocketException:
-        //     An error occurred when attempting to access the socket. See the Remarks section
-        //     for more information.
-        //
-        //   T:System.ObjectDisposedException:
-        //     The System.Net.Sockets.Socket has been closed.
-        public void SetSocketOption(SocketOptionLevel optionLevel, SocketOptionName optionName, int optionValue)
-        {
-            switch (optionName)
-            {
-                case SocketOptionName.ReceiveTimeout:
-                    _receiveTimeout = optionValue;
-                    break;
-
-                case SocketOptionName.SendTimeout:
-                    _sendTimeout = optionValue;
-                    break;
-
-                default:
-                    throw new NotImplementedException("SetSocketOption option not implemented");
-            }
-        }
-
-        private System.Net.Sockets.Socket _socket = null;
-        private int _receiveTimeout = TIMEOUT_MILLISECONDS;
-        private int _sendTimeout = TIMEOUT_MILLISECONDS;
-
-        private readonly static ManualResetEvent _clientDone =
-            new ManualResetEvent(false);
-
-        private const int TIMEOUT_MILLISECONDS = 1000;
-
-    }
-
-    //
-    // Summary:
-    //     Specifies socket send and receive behaviors.
-    [Flags]
-    public enum SocketFlags
-    {
-        //
-        // Summary:
-        //     Use no flags for this call.
-        None = 0,
-        ////
-        //// Summary:
-        ////     Process out-of-band data.
-        //OutOfBand = 1,
-        ////
-        //// Summary:
-        ////     Peek at the incoming message.
-        //Peek = 2,
-        ////
-        //// Summary:
-        ////     Send without using routing tables.
-        //DontRoute = 4,
-        ////
-        //// Summary:
-        ////     Provides a standard value for the number of WSABUF structures that are used to
-        ////     send and receive data.
-        //MaxIOVectorLength = 16,
-        ////
-        //// Summary:
-        ////     The message was too large to fit into the specified buffer and was truncated.
-        //Truncated = 256,
-        ////
-        //// Summary:
-        ////     Indicates that the control data did not fit into an internal 64-KB buffer and
-        ////     was truncated.
-        //ControlDataTruncated = 512,
-        ////
-        //// Summary:
-        ////     Indicates a broadcast packet.
-        //Broadcast = 1024,
-        ////
-        //// Summary:
-        ////     Indicates a multicast packet.
-        //Multicast = 2048,
-        ////
-        //// Summary:
-        ////     Partial send or receive for message.
-        //Partial = 32768
-    }
-
-    //
-    // Summary:
-    //     Defines socket option levels for the System.Net.Sockets.Socket.SetSocketOption(System.Net.Sockets.SocketOptionLevel,System.Net.Sockets.SocketOptionName,System.Int32)
-    //     and System.Net.Sockets.Socket.GetSocketOption(System.Net.Sockets.SocketOptionLevel,System.Net.Sockets.SocketOptionName)
-    //     methods.
-    public enum SocketOptionLevel
-    {
-        //
-        // Summary:
-        //     System.Net.Sockets.Socket options apply only to IP sockets.
-        IP = 0,
-        //
-        // Summary:
-        //     System.Net.Sockets.Socket options apply only to TCP sockets.
-        Tcp = 6,
-        //
-        // Summary:
-        //     System.Net.Sockets.Socket options apply only to UDP sockets.
-        Udp = 17,
-        //
-        // Summary:
-        //     System.Net.Sockets.Socket options apply only to IPv6 sockets.
-        IPv6 = 41,
-        //
-        // Summary:
-        //     System.Net.Sockets.Socket options apply to all sockets.
-        Socket = 65535
-    }
-
-    //
-    // Summary:
-    //     Defines configuration option names.
-    public enum SocketOptionName
-    {
-        //
-        // Summary:
-        //     Close the socket gracefully without lingering.
-        DontLinger = -129,
-        //
-        // Summary:
-        //     Enables a socket to be bound for exclusive access.
-        ExclusiveAddressUse = -5,
-        //
-        // Summary:
-        //     Record debugging information.
-        Debug = 1,
-        //
-        // Summary:
-        //     Specifies the IP options to be inserted into outgoing datagrams.
-        IPOptions = 1,
-        //
-        // Summary:
-        //     Disables the Nagle algorithm for send coalescing.
-        NoDelay = 1,
-        //
-        // Summary:
-        //     Send UDP datagrams with checksum set to zero.
-        NoChecksum = 1,
-        //
-        // Summary:
-        //     The socket is listening.
-        AcceptConnection = 2,
-        //
-        // Summary:
-        //     Indicates that the application provides the IP header for outgoing datagrams.
-        HeaderIncluded = 2,
-        //
-        // Summary:
-        //     Use urgent data as defined in RFC-1222. This option can be set only once; after
-        //     it is set, it cannot be turned off.
-        BsdUrgent = 2,
-        //
-        // Summary:
-        //     Use expedited data as defined in RFC-1222. This option can be set only once;
-        //     after it is set, it cannot be turned off.
-        Expedited = 2,
-        //
-        // Summary:
-        //     Change the IP header type of the service field.
-        TypeOfService = 3,
-        //
-        // Summary:
-        //     Allows the socket to be bound to an address that is already in use.
-        ReuseAddress = 4,
-        //
-        // Summary:
-        //     Set the IP header Time-to-Live field.
-        IpTimeToLive = 4,
-        //
-        // Summary:
-        //     Use keep-alives.
-        KeepAlive = 8,
-        //
-        // Summary:
-        //     Set the interface for outgoing multicast packets.
-        MulticastInterface = 9,
-        //
-        // Summary:
-        //     An IP multicast Time to Live.
-        MulticastTimeToLive = 10,
-        //
-        // Summary:
-        //     An IP multicast loopback.
-        MulticastLoopback = 11,
-        //
-        // Summary:
-        //     Add an IP group membership.
-        AddMembership = 12,
-        //
-        // Summary:
-        //     Drop an IP group membership.
-        DropMembership = 13,
-        //
-        // Summary:
-        //     Do not fragment IP datagrams.
-        DontFragment = 14,
-        //
-        // Summary:
-        //     Join a source group.
-        AddSourceMembership = 15,
-        //
-        // Summary:
-        //     Do not route; send the packet directly to the interface addresses.
-        DontRoute = 16,
-        //
-        // Summary:
-        //     Drop a source group.
-        DropSourceMembership = 16,
-        //
-        // Summary:
-        //     Block data from a source.
-        BlockSource = 17,
-        //
-        // Summary:
-        //     Unblock a previously blocked source.
-        UnblockSource = 18,
-        //
-        // Summary:
-        //     Return information about received packets.
-        PacketInformation = 19,
-        //
-        // Summary:
-        //     Set or get the UDP checksum coverage.
-        ChecksumCoverage = 20,
-        //
-        // Summary:
-        //     Specifies the maximum number of router hops for an Internet Protocol version
-        //     6 (IPv6) packet. This is similar to Time to Live (TTL) for Internet Protocol
-        //     version 4.
-        HopLimit = 21,
-        //
-        // Summary:
-        //     Permit sending broadcast messages on the socket.
-        Broadcast = 32,
-        //
-        // Summary:
-        //     Bypass hardware when possible.
-        UseLoopback = 64,
-        //
-        // Summary:
-        //     Linger on close if unsent data is present.
-        Linger = 128,
-        //
-        // Summary:
-        //     Receives out-of-band data in the normal data stream.
-        OutOfBandInline = 256,
-        //
-        // Summary:
-        //     Specifies the total per-socket buffer space reserved for sends. This is unrelated
-        //     to the maximum message size or the size of a TCP window.
-        SendBuffer = 4097,
-        //
-        // Summary:
-        //     Specifies the total per-socket buffer space reserved for receives. This is unrelated
-        //     to the maximum message size or the size of a TCP window.
-        ReceiveBuffer = 4098,
-        //
-        // Summary:
-        //     Specifies the low water mark for Overload:System.Net.Sockets.Socket.Send operations.
-        SendLowWater = 4099,
-        //
-        // Summary:
-        //     Specifies the low water mark for Overload:System.Net.Sockets.Socket.Receive operations.
-        ReceiveLowWater = 4100,
-        //
-        // Summary:
-        //     Send a time-out. This option applies only to synchronous methods; it has no effect
-        //     on asynchronous methods such as the System.Net.Sockets.Socket.BeginSend(System.Byte[],System.Int32,System.Int32,System.Net.Sockets.SocketFlags,System.AsyncCallback,System.Object)
-        //     method.
-        SendTimeout = 4101,
-        //
-        // Summary:
-        //     Receive a time-out. This option applies only to synchronous methods; it has no
-        //     effect on asynchronous methods such as the System.Net.Sockets.Socket.BeginSend(System.Byte[],System.Int32,System.Int32,System.Net.Sockets.SocketFlags,System.AsyncCallback,System.Object)
-        //     method.
-        ReceiveTimeout = 4102,
-        //
-        // Summary:
-        //     Get the error status and clear.
-        Error = 4103,
-        //
-        // Summary:
-        //     Get the socket type.
-        Type = 4104,
-        //
-        // Summary:
-        //     Updates an accepted socket's properties by using those of an existing socket.
-        //     This is equivalent to using the Winsock2 SO_UPDATE_ACCEPT_CONTEXT socket option
-        //     and is supported only on connection-oriented sockets.
-        UpdateAcceptContext = 28683,
-        //
-        // Summary:
-        //     Updates a connected socket's properties by using those of an existing socket.
-        //     This is equivalent to using the Winsock2 SO_UPDATE_CONNECT_CONTEXT socket option
-        //     and is supported only on connection-oriented sockets.
-        UpdateConnectContext = 28688,
-        //
-        // Summary:
-        //     Not supported; will throw a System.Net.Sockets.SocketException if used.
-        MaxConnections = int.MaxValue
-    }
-}

S7.Net.Core/project.json

@@ -1,16 +0,0 @@
-{
-  "dependencies": {
-    "Microsoft.NETCore.UniversalWindowsPlatform": "5.4.0"
-  },
-  "frameworks": {
-    "uap10.0.10240": {}
-  },
-  "runtimes": {
-    "win10-arm": {},
-    "win10-arm-aot": {},
-    "win10-x86": {},
-    "win10-x86-aot": {},
-    "win10-x64": {},
-    "win10-x64-aot": {}
-  }
-}

S7.Net.UnitTest/CommunicationTests/Clock.cs

@@ -0,0 +1,259 @@
+using System;
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Protocol;
+
+namespace S7.Net.UnitTest.CommunicationTests;
+
+[TestClass]
+public class Clock
+{
+    [TestMethod, Timeout(1000)]
+    public async Task Read_Clock_Value()
+    {
+        var cs = new CommunicationSequence
+        {
+            ConnectionOpenTemplates.ConnectionRequestConfirm,
+            ConnectionOpenTemplates.CommunicationSetup,
+            {
+                """
+                    // TPKT
+                    03 00 00 1d
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 read clock
+                    // UserData header
+                    32 07 00 00 PDU1 PDU2
+                    // Parameter length
+                    00 08
+                    // Data length
+                    00 04
+
+                    // Parameter
+                    // Head
+                    00 01 12
+                    // Length
+                    04
+                    // Method (Request/Response): Req
+                    11
+                    // Type request (4...) Function group timers (...7)
+                    47
+                    // Subfunction: read clock
+                    01
+                    // Sequence number
+                    00
+
+                    // Data
+                    // Return code
+                    0a
+                    // Transport size
+                    00
+                    // Payload length
+                    00 00
+                """,
+                """
+                    // TPKT
+                    03 00 00 2b
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 read clock response
+                    // UserData header
+                    32 07 00 00 PDU1 PDU2
+                    // Parameter length
+                    00 0c
+                    // Data length
+                    00 0e
+
+                    // Parameter
+                    // Head
+                    00 01 12
+                    // Length
+                    08
+                    // Method (Request/Response): Res
+                    12
+                    // Type response (8...) Function group timers (...7)
+                    87
+                    // Subfunction: read clock
+                    01
+                    // Sequence number
+                    01
+                    // Data unit reference
+                    00
+                    // Last data unit? Yes
+                    00
+                    // Error code
+                    00 00
+
+                    // Data
+                    // Error code
+                    ff
+                    // Transport size: OCTET STRING
+                    09
+                    // Length
+                    00 0a
+
+                    // Timestamp
+                    // Reserved
+                    00
+                    // Year 1
+                    19
+                    // Year 2
+                    14
+                    // Month
+                    08
+                    // Day
+                    20
+                    // Hour
+                    11
+                    // Minute
+                    59
+                    // Seconds
+                    43
+                    // Milliseconds: 912..., Day of week: ...4
+                    91 24
+                """
+            }
+        };
+
+        static async Task Client(int port)
+        {
+            var conn = new Plc(IPAddress.Loopback.ToString(), port, new TsapPair(new Tsap(1, 2), new Tsap(3, 4)));
+            await conn.OpenAsync();
+            var time = await conn.ReadClockAsync();
+
+            Assert.AreEqual(new DateTime(2014, 8, 20, 11, 59, 43, 912), time);
+            conn.Close();
+        }
+
+        await Task.WhenAll(cs.Serve(out var port), Client(port));
+    }
+
+    [TestMethod, Timeout(1000)]
+    public async Task Write_Clock_Value()
+    {
+        var cs = new CommunicationSequence
+        {
+            ConnectionOpenTemplates.ConnectionRequestConfirm,
+            ConnectionOpenTemplates.CommunicationSetup,
+            {
+                """
+                    // TPKT
+                    03 00 00 27
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 read clock
+                    // UserData header
+                    32 07 00 00 PDU1 PDU2
+                    // Parameter length
+                    00 08
+                    // Data length
+                    00 0e
+
+                    // Parameter
+                    // Head
+                    00 01 12
+                    // Length
+                    04
+                    // Method (Request/Response): Req
+                    11
+                    // Type request (4...) Function group timers (...7)
+                    47
+                    // Subfunction: write clock
+                    02
+                    // Sequence number
+                    00
+
+                    // Data
+                    // Return code
+                    ff
+                    // Transport size
+                    09
+                    // Payload length
+                    00 0a
+
+                    // Payload
+                    // Timestamp
+                    // Reserved
+                    00
+                    // Year 1
+                    19
+                    // Year 2
+                    14
+                    // Month
+                    08
+                    // Day
+                    20
+                    // Hour
+                    11
+                    // Minute
+                    59
+                    // Seconds
+                    43
+                    // Milliseconds: 912..., Day of week: ...4
+                    91 24
+                """,
+                """
+                // TPKT
+                    03 00 00 21
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 read clock response
+                    // UserData header
+                    32 07 00 00 PDU1 PDU2
+                    // Parameter length
+                    00 0c
+                    // Data length
+                    00 04
+
+                    // Parameter
+                    // Head
+                    00 01 12
+                    // Length
+                    08
+                    // Method (Request/Response): Res
+                    12
+                    // Type response (8...) Function group timers (...7)
+                    87
+                    // Subfunction: write clock
+                    02
+                    // Sequence number
+                    01
+                    // Data unit reference
+                    00
+                    // Last data unit? Yes
+                    00
+                    // Error code
+                    00 00
+
+                    // Data
+                    // Error code
+                    0a
+                    // Transport size: NONE
+                    00
+                    // Length
+                    00 00
+                """
+            }
+        };
+
+        static async Task Client(int port)
+        {
+            var conn = new Plc(IPAddress.Loopback.ToString(), port, new TsapPair(new Tsap(1, 2), new Tsap(3, 4)));
+            await conn.OpenAsync();
+            await conn.WriteClockAsync(new DateTime(2014, 08, 20, 11, 59, 43, 912));
+
+            conn.Close();
+        }
+
+        await Task.WhenAll(cs.Serve(out var port), Client(port));
+    }
+}

S7.Net.UnitTest/CommunicationTests/ConnectionOpen.cs

@@ -0,0 +1,28 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Protocol;
+
+namespace S7.Net.UnitTest.CommunicationTests;
+
+[TestClass]
+public class ConnectionOpen
+{
+    [TestMethod]
+    public async Task Does_Not_Throw()
+    {
+        var cs = new CommunicationSequence {
+            ConnectionOpenTemplates.ConnectionRequestConfirm,
+            ConnectionOpenTemplates.CommunicationSetup
+        };
+
+        async Task Client(int port)
+        {
+            var conn = new Plc(IPAddress.Loopback.ToString(), port, new TsapPair(new Tsap(1, 2), new Tsap(3, 4)));
+            await conn.OpenAsync();
+            conn.Close();
+        }
+
+        await Task.WhenAll(cs.Serve(out var port), Client(port));
+    }
+}

S7.Net.UnitTest/CommunicationTests/ConnectionOpenTemplates.cs

@@ -0,0 +1,107 @@
+namespace S7.Net.UnitTest.CommunicationTests;
+
+internal static class ConnectionOpenTemplates
+{
+    public static RequestResponsePair ConnectionRequestConfirm { get; } = new RequestResponsePair(
+        """
+            // TPKT
+            03 // Version
+            00 // Reserved
+            00 16 // Length
+
+            // CR
+            11 // Number of bytes following
+            E0 // CR / Credit
+            00 00 // Destination reference, unused
+            __ __ // Source reference, unused
+            00 // Class / Option
+
+            // Source TSAP
+            C1 // Parameter code
+            02 // Parameter length
+            TSAP_SRC_CHAN // Channel
+            TSAP_SRC_POS // Position
+
+            // Destination TSAP
+            C2 // Parameter code
+            02 // Parameter length
+            TSAP_DEST_CHAN // Channel
+            TSAP_DEST_POS // Position
+
+            // PDU Size parameter
+            C0 // Parameter code
+            01 // Parameter length
+            0A // 1024 byte PDU (2 ^ 10)
+        """,
+        """
+            // TPKT
+            03 // Version
+            00 // Reserved
+            00 0B // Length
+
+            // CC
+            06 // Length
+            D0 // CC / Credit
+            00 00 // Destination reference
+            00 00 // Source reference
+            00 // Class / Option
+        """
+    );
+
+    public static RequestResponsePair CommunicationSetup { get; } = new RequestResponsePair(
+        """
+            // TPKT
+            03 // Version
+            00 // Reserved
+            00 19 // Length
+
+            // Data header
+            02 // Length
+            F0 // Data identifier
+            80 // PDU number and end of transmission
+
+            // S7 header
+            32 // Protocol ID
+            01 // Message type job request
+            00 00 // Reserved
+            PDU1 PDU2 // PDU reference
+            00 08 // Parameter length (Communication Setup)
+            00 00 // Data length
+
+            // Communication Setup
+            F0 // Function code
+            00 // Reserved
+            00 03 // Max AMQ caller
+            00 03 // Max AMQ callee
+            03 C0 // PDU size (960)
+        """,
+        """
+            // TPKT
+            03 // Version
+            00 // Reserved
+            00 1B // Length
+
+            // Data header
+            02 // Length
+            F0 // Data identifier
+            80 // PDU number and end of transmission
+
+            // S7 header
+            32 // Protocol ID
+            03 // Message type ack data
+            00 00 // Reserved
+            PDU1 PDU2 // PDU reference
+            00 08 // Parameter length (Communication Setup)
+            00 00 // Data length
+            00 // Error class
+            00 // Error code
+
+            // Communication Setup
+            F0 // Function code
+            00 // Reserved
+            00 03 // Max AMQ caller
+            00 03 // Max AMQ callee
+            03 C0 // PDU size (960)
+        """
+    );
+}

S7.Net.UnitTest/CommunicationTests/ReadPlcStatus.cs

@@ -0,0 +1,57 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Protocol;
+
+namespace S7.Net.UnitTest.CommunicationTests;
+
+[TestClass]
+public class ReadPlcStatus
+{
+    [TestMethod]
+    public async Task Read_Status_Run()
+    {
+        var cs = new CommunicationSequence {
+            ConnectionOpenTemplates.ConnectionRequestConfirm,
+            ConnectionOpenTemplates.CommunicationSetup,
+            {
+                """
+                    // TPKT
+                    03 00 00 21
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 SZL read
+                    32 07 00 00 PDU1 PDU2 00 08 00 08 00 01 12 04 11 44
+                    01 00 ff 09 00 04 04 24 00 00
+                """,
+                """
+                    // TPKT
+                    03 00 00 3d
+
+                    // COTP
+                    02 f0 80
+
+                    // S7 SZL response
+                    32 07 00 00 PDU1 PDU2 00 0c 00 20 00 01 12 08 12 84
+                    01 02 00 00 00 00 ff 09 00 1c 04 24 00 00 00 14
+                    00 01 51 44 ff 08 00 00 00 00 00 00 00 00 14 08
+                    20 12 05 28 34 94
+                """
+            }
+        };
+
+        async Task Client(int port)
+        {
+            var conn = new Plc(IPAddress.Loopback.ToString(), port, new TsapPair(new Tsap(1, 2), new Tsap(3, 4)));
+            await conn.OpenAsync();
+            var status = await conn.ReadStatusAsync();
+
+            Assert.AreEqual(0x08, status);
+            conn.Close();
+        }
+
+        await Task.WhenAll(cs.Serve(out var port), Client(port));
+    }
+}

S7.Net.UnitTest/ConnectionCloseTest.cs

@@ -0,0 +1,181 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using System.IO;
+using System.Linq;
+using System.Net.Sockets;
+using System.Reflection;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net.UnitTest
+{
+    /// <summary>
+    /// Test stream which only gives 1 byte per read.
+    /// </summary>
+    class TestStreamConnectionClose : Stream
+    {
+        private readonly CancellationTokenSource _cancellationTokenSource;
+
+        public TestStreamConnectionClose(CancellationTokenSource cancellationTokenSource)
+        {
+            _cancellationTokenSource = cancellationTokenSource;
+        }
+        public override bool CanRead => false;
+
+        public override bool CanSeek => throw new NotImplementedException();
+
+        public override bool CanWrite => true;
+
+        public override long Length => throw new NotImplementedException();
+
+        public override long Position { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
+
+        public override void Flush()
+        {
+            throw new NotImplementedException();
+        }
+        
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            _cancellationTokenSource.Cancel();
+        }
+    }
+
+    /// <summary>
+    /// These tests are intended to test <see cref="StreamExtensions"/> functions and other stream-related special cases.
+    /// </summary>
+    [TestClass]
+    public class ConnectionCloseTest
+    {
+        const short TestServerPort = 31122;
+        const string TestServerIp = "127.0.0.1";
+
+        [TestMethod]
+        public async Task Test_CancellationDuringTransmission()
+        {
+            var plc = new Plc(CpuType.S7300, TestServerIp, TestServerPort, 0, 2);
+
+            // Set up a shared cancellation source so we can let the stream
+            // initiate cancel after some data has been written to it.
+            var cancellationSource = new CancellationTokenSource();
+            var cancellationToken = cancellationSource.Token;
+
+            var stream = new TestStreamConnectionClose(cancellationSource);
+            var requestData = new byte[100]; // empty data, it does not matter what is in there
+
+            // Set up access to private method and field
+            var dynMethod = plc.GetType().GetMethod("NoLockRequestTpduAsync",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            if (dynMethod == null)
+            {
+                throw new NullReferenceException("Could not find method 'NoLockRequestTpduAsync' on Plc object.");
+            }
+            var tcpClientField = plc.GetType().GetField("tcpClient", BindingFlags.NonPublic | BindingFlags.Instance);
+            if (tcpClientField == null)
+            {
+                throw new NullReferenceException("Could not find field 'tcpClient' on Plc object.");
+            }
+
+            // Set a value to tcpClient field so we can later ensure that it has been closed.
+            tcpClientField.SetValue(plc, new TcpClient());
+            var tcpClientValue = tcpClientField.GetValue(plc);
+            Assert.IsNotNull(tcpClientValue);
+            
+            try
+            {
+                var result = (Task<COTP.TPDU>) dynMethod.Invoke(plc, new object[] { stream, requestData, cancellationToken });
+                await result;
+            }
+            catch (OperationCanceledException)
+            {
+                Console.WriteLine("Task was cancelled as expected.");
+
+                // Ensure that the plc connection was closed since the task was cancelled
+                // after data has been sent through the network. We expect that the tcpClient
+                // object was set to NULL
+                var tcpClientValueAfter = tcpClientField.GetValue(plc);
+                Assert.IsNull(tcpClientValueAfter);
+                return;
+            }
+            catch (Exception e)
+            {
+                Assert.Fail($"Wrong exception type received. Expected {typeof(OperationCanceledException)}, received {e.GetType()}.");
+            }
+
+            // Ensure test fails if cancellation did not occur.
+            Assert.Fail("Task was not cancelled as expected.");
+        }
+
+        [TestMethod]
+        public async Task Test_CancellationBeforeTransmission()
+        {
+            var plc = new Plc(CpuType.S7300, TestServerIp, TestServerPort, 0, 2);
+
+            // Set up a cancellation source
+            var cancellationSource = new CancellationTokenSource();
+            var cancellationToken = cancellationSource.Token;
+
+            var stream = new TestStreamConnectionClose(cancellationSource);
+            var requestData = new byte[100]; // empty data, it does not matter what is in there
+
+            // Set up access to private method and field
+            var dynMethod = plc.GetType().GetMethod("NoLockRequestTpduAsync",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            if (dynMethod == null)
+            {
+                throw new NullReferenceException("Could not find method 'NoLockRequestTpduAsync' on Plc object.");
+            }
+            var tcpClientField = plc.GetType().GetField("tcpClient", BindingFlags.NonPublic | BindingFlags.Instance);
+            if (tcpClientField == null)
+            {
+                throw new NullReferenceException("Could not find field 'tcpClient' on Plc object.");
+            }
+
+            // Set a value to tcpClient field so we can later ensure that it has been closed.
+            tcpClientField.SetValue(plc, new TcpClient());
+            var tcpClientValue = tcpClientField.GetValue(plc);
+            Assert.IsNotNull(tcpClientValue);
+
+            try
+            {
+                // cancel the task before we start transmitting data
+                cancellationSource.Cancel();
+                var result = (Task<COTP.TPDU>)dynMethod.Invoke(plc, new object[] { stream, requestData, cancellationToken });
+                await result;
+            }
+            catch (OperationCanceledException)
+            {
+                Console.WriteLine("Task was cancelled as expected.");
+
+                // Ensure that the plc connection was not closed, since we cancelled the task before
+                // sending data through the network. We expect that the tcpClient
+                // object was NOT set to NULL
+                var tcpClientValueAfter = tcpClientField.GetValue(plc);
+                Assert.IsNotNull(tcpClientValueAfter);
+                return;
+            }
+            catch (Exception e)
+            {
+                Assert.Fail($"Wrong exception type received. Expected {typeof(OperationCanceledException)}, received {e.GetType()}.");
+            }
+
+            // Ensure test fails if cancellation did not occur.
+            Assert.Fail("Task was not cancelled as expected.");
+        }
+    }
+}

S7.Net.UnitTest/ConnectionRequestTest.cs

@@ -0,0 +1,82 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Protocol;
+
+namespace S7.Net.UnitTest
+{
+    [TestClass]
+    public class ConnectionRequestTest
+    {
+        [TestMethod]
+        public void Test_ConnectionRequest_S7_200()
+        {
+            CollectionAssert.AreEqual(MakeConnectionRequest(16, 0, 16, 1),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7200, 0, 0)));
+        }
+
+        [TestMethod]
+        public void Test_ConnectionRequest_S7_300()
+        {
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 0),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7300, 0, 0)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 1),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7300, 0, 1)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 33),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7300, 1, 1)));
+        }
+
+        [TestMethod]
+        public void Test_ConnectionRequest_S7_400()
+        {
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 0),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7400, 0, 0)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 1),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7400, 0, 1)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 33),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S7400, 1, 1)));
+        }
+
+        [TestMethod]
+        public void Test_ConnectionRequest_S7_1200()
+        {
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 0),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71200, 0, 0)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 1),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71200, 0, 1)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 33),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71200, 1, 1)));
+        }
+
+        [TestMethod]
+        public void Test_ConnectionRequest_S7_1500()
+        {
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 0),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71500, 0, 0)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 1),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71500, 0, 1)));
+            CollectionAssert.AreEqual(MakeConnectionRequest(1, 0, 3, 33),
+                ConnectionRequest.GetCOTPConnectionRequest(TsapPair.GetDefaultTsapPair(CpuType.S71500, 1, 1)));
+        }
+
+        private static byte[] MakeConnectionRequest(byte sourceTsap1, byte sourceTsap2, byte destTsap1, byte destTsap2)
+        {
+            return new byte[]
+            {
+                3, 0, 0, 22, //TPKT
+                17, //COTP Header Length
+                224, //Connect Request
+                0, 0, //Destination Reference
+                0, 46, //Source Reference
+                0, //Flags
+                193, //Parameter Code (src-tasp)
+                2, //Parameter Length
+                sourceTsap1, sourceTsap2, //Source TASP
+                194, //Parameter Code (dst-tasp)
+                2, //Parameter Length
+                destTsap1, destTsap2, //Destination TASP
+                192, //Parameter Code (tpdu-size)
+                1, //Parameter Length
+                10 //TPDU Size (2^11 = 2048)
+            };
+        }
+    }
+}

S7.Net.UnitTest/ConvertersUnitTest.cs

@@ -24,5 +24,21 @@ namespace S7.Net.UnitTest
             Assert.IsFalse(dummyByte.SelectBit(7));
 
         }
+
+        [TestMethod]
+        public void T01_TestSetBit()
+        {
+            byte dummyByte = 0xAA; // 1010 1010
+            dummyByte.SetBit(0, true);
+            dummyByte.SetBit(1, false);
+            dummyByte.SetBit(2, true);
+            dummyByte.SetBit(3, false);
+            Assert.AreEqual<byte>(dummyByte, 0xA5);// 1010 0101
+            dummyByte.SetBit(4, true);
+            dummyByte.SetBit(5, true);
+            dummyByte.SetBit(6, true);
+            dummyByte.SetBit(7, true);
+            Assert.AreEqual<byte>(dummyByte, 0xF5);// 1111 0101
+        }
     }
 }

S7.Net.UnitTest/Framework/IsExternalInit.cs

@@ -0,0 +1,7 @@
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices
+{
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    internal record IsExternalInit;
+}

S7.Net.UnitTest/Helpers/S7TestServer.cs

@@ -9,6 +9,7 @@ namespace S7.Net.UnitTest.Helpers
         static private byte[] DB1 = new byte[1024];  // Our DB1
         static private byte[] DB2 = new byte[64000]; // Our DB2
         static private byte[] DB3 = new byte[1024]; // Our DB3
+        static private byte[] DB4 = new byte[6] { 3, 128, 1, 0, 197, 104 }; // Our DB4
 
         private static S7Server.TSrvCallback TheEventCallBack; // <== Static var containig the callback
         private static S7Server.TSrvCallback TheReadCallBack; // <== Static var containig the callback
@@ -28,7 +29,7 @@ namespace S7.Net.UnitTest.Helpers
             Console.WriteLine(Server.EventText(ref Event));
         }
 
-        public static void Start()
+        public static void Start(short port)
         {
             Server = new S7Server();
             // Share some resources with our virtual PLC
@@ -36,9 +37,10 @@ namespace S7.Net.UnitTest.Helpers
                                 1,                   // Its number is 1 (DB1)
                                 DB1,                 // Our buffer for DB1
                                 DB1.Length);         // Its size
-            // Do the same for DB2 and DB3
+            // Do the same for DB2, DB3, and DB4
             Server.RegisterArea(S7Server.srvAreaDB, 2, DB2, DB2.Length);
             Server.RegisterArea(S7Server.srvAreaDB, 3, DB3, DB3.Length);
+            Server.RegisterArea(S7Server.srvAreaDB, 4, DB4, DB4.Length);
 
             // Exclude read event to avoid the double report
             // Set the callbacks (using the static var to avoid the garbage collect)
@@ -57,7 +59,14 @@ namespace S7.Net.UnitTest.Helpers
             // Start the server onto the default adapter.
             // To select an adapter we have to use Server->StartTo("192.168.x.y").
             // Start() is the same of StartTo("0.0.0.0");       
+
+            Server.SetParam(S7Consts.p_u16_LocalPort, ref port);
+
             int Error = Server.Start();
+            if (Error != 0)
+            {
+                throw new Exception($"Error starting Snap7 server: {Server.ErrorText(Error)}");
+            }
             //if (Error == 0)
             //{
             //    // Now the server is running ... wait a key to terminate

S7.Net.UnitTest/Helpers/TestClass.cs

@@ -1,4 +1,6 @@
 
+using S7.Net.Types;
+
 namespace S7.Net.UnitTest.Helpers
 {
     class TestClass
@@ -35,16 +37,32 @@ namespace S7.Net.UnitTest.Helpers
         /// <summary>
         /// DB1.DBD4
         /// </summary>
-        public double RealVariable { get; set; }
+        public double LRealVariable { get; set; }
 
         /// <summary>
         /// DB1.DBD8
         /// </summary>
-        public int DIntVariable { get; set; }
+        public float RealVariable { get; set; }
 
         /// <summary>
         /// DB1.DBD12
         /// </summary>
+        public int DIntVariable { get; set; }
+
+        /// <summary>
+        /// DB1.DBD16
+        /// </summary>
         public ushort DWordVariable { get; set; }
+
+        /// <summary>
+        /// DB1.DBX20.0
+        /// </summary>
+        [S7String(S7StringType.S7WString, 10)]
+        public string WStringVariable { get; set; }
+        /// <summary>
+        /// DB1.DBX44.0
+        /// </summary>
+        [S7String(S7StringType.S7String, 10)]
+        public string StringVariable { get; set; }
     }
 }

S7.Net.UnitTest/Helpers/TestClassWithArrays.cs

@@ -15,10 +15,12 @@ namespace S7.UnitTest.Helpers
         public ushort[] UShorts { get; set; } = new ushort[2];
         public int[] Ints { get; set; } = new int[2];
         public double[] Doubles { get; set; } = new double[2];
+        public float[] Singles { get; set; } = new float[2];
 
         public short Short { get; set; }
         public ushort UShort { get; set; }
         public int Int { get; set; }
         public double Double { get; set; }
+        public float Single { get; set; }
     }
 }

S7.Net.UnitTest/Helpers/TestClassWithNestedClass.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace S7.Net.UnitTest.Helpers
+{
+    class TestClassInnerWithBool
+    {
+        public bool BitVariable00 { get; set; }
+    }
+
+    class TestClassInnerWithByte
+    {
+        public byte ByteVariable00 { get; set; }
+    }
+
+    class TestClassInnerWithShort
+    {
+        public short ShortVarialbe00 { get; set; }
+    }
+
+    class TestClassWithNestedClass
+    {
+        /// <summary>
+        /// DB1.DBX0.0
+        /// </summary>
+        public bool BitVariable00 { get; set; }
+
+        /// <summary>
+        /// DB1.DBX0.1
+        /// </summary>
+        public TestClassInnerWithBool BitVariable01 { get; set; } = new TestClassInnerWithBool();
+
+        /// <summary>
+        /// DB1.DBB1.0
+        /// </summary>
+        public TestClassInnerWithByte ByteVariable02 { get; set; } = new TestClassInnerWithByte();
+
+        /// <summary>
+        /// DB1.DBX2.0
+        /// </summary>
+        public bool BitVariable03 { get; set; }
+
+        /// <summary>
+        /// DB1.DBW4
+        /// </summary>
+        public TestClassInnerWithShort ShortVariable04 { get; set; } = new TestClassInnerWithShort();
+    }
+}

S7.Net.UnitTest/Helpers/TestSmallClass.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace S7.UnitTest.Helpers
+{
+    class TestSmallClass
+    {
+        public bool Bool1 { get; set; }
+    }
+}

S7.Net.UnitTest/Helpers/TestStruct.cs

@@ -1,4 +1,5 @@
-
+using S7.Net.Types;
+
 namespace S7.Net.UnitTest.Helpers
 {
     public struct TestStruct
@@ -7,6 +8,7 @@ namespace S7.Net.UnitTest.Helpers
         /// DB1.DBX0.0
         /// </summary>
         public bool BitVariable00;
+
         public bool BitVariable01;
         public bool BitVariable02;
         public bool BitVariable03;
@@ -19,6 +21,7 @@ namespace S7.Net.UnitTest.Helpers
         /// DB1.DBX1.0           
         /// </summary>           
         public bool BitVariable10;
+
         public bool BitVariable11;
         public bool BitVariable12;
         public bool BitVariable13;
@@ -35,16 +38,33 @@ namespace S7.Net.UnitTest.Helpers
         /// <summary>
         /// DB1.DBD4
         /// </summary>
-        public double RealVariable;
+        public double LRealVariable;
 
         /// <summary>
         /// DB1.DBD8
         /// </summary>
-        public int DIntVariable;
+        public float RealVariable;
 
         /// <summary>
         /// DB1.DBD12
         /// </summary>
+        public int DIntVariable;
+
+        /// <summary>
+        /// DB1.DBD16
+        /// </summary>
         public ushort DWordVariable;
+
+        /// <summary>
+        /// DB1.DBX20.0
+        /// </summary>
+        [S7String(S7StringType.S7WString, 10)] 
+        public string WStringVariable;
+
+        /// <summary>
+        /// DB1.DBX44.0
+        /// </summary>
+        [S7String(S7StringType.S7String, 10)]
+        public string StringVariable;
     }
 }

S7.Net.UnitTest/Infrastructure/CommunicationSequence.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Buffers;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+
+namespace S7.Net.UnitTest;
+
+internal class CommunicationSequence : IEnumerable<RequestResponsePair>
+{
+    private readonly List<RequestResponsePair> _requestResponsePairs = new List<RequestResponsePair>();
+
+    public void Add(RequestResponsePair requestResponsePair)
+    {
+        _requestResponsePairs.Add(requestResponsePair);
+    }
+
+    public void Add(string requestPattern, string responsePattern)
+    {
+        _requestResponsePairs.Add(new RequestResponsePair(requestPattern, responsePattern));
+    }
+
+    public IEnumerator<RequestResponsePair> GetEnumerator()
+    {
+        return _requestResponsePairs.GetEnumerator();
+    }
+
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+
+    public Task Serve(out int port)
+    {
+        var socket = CreateBoundListenSocket(out port);
+        socket.Listen(0);
+
+        async Task Impl()
+        {
+            await Task.Yield();
+            var socketIn = socket.Accept();
+
+            var buffer = ArrayPool<byte>.Shared.Rent(1024);
+            try
+            {
+                foreach (var pair in _requestResponsePairs)
+                {
+                    var bytesReceived = socketIn.Receive(buffer, SocketFlags.None);
+
+                    var received = buffer.Take(bytesReceived).ToArray();
+                    Console.WriteLine($"=> {BitConverter.ToString(received)}");
+
+                    var response = Responder.Respond(pair, received);
+
+                    Console.WriteLine($"<= {BitConverter.ToString(response)}");
+                    socketIn.Send(response);
+                }
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(buffer);
+            }
+
+            socketIn.Close();
+        }
+
+        return Impl();
+    }
+
+    private static Socket CreateBoundListenSocket(out int port)
+    {
+        var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+        var endpoint = new IPEndPoint(IPAddress.Loopback, 0);
+
+        socket.Bind(endpoint);
+
+        var localEndpoint = (IPEndPoint)socket.LocalEndPoint!;
+        port = localEndpoint.Port;
+
+        return socket;
+    }
+}

S7.Net.UnitTest/Infrastructure/RequestResponsePair.cs

@@ -0,0 +1,3 @@
+namespace S7.Net.UnitTest;
+
+internal record RequestResponsePair(string RequestPattern, string ResponsePattern);

S7.Net.UnitTest/Infrastructure/Responder.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.IO;
+
+namespace S7.Net.UnitTest;
+
+internal static class Responder
+{
+    private const string Comment = "//";
+    private static char[] Space = " ".ToCharArray();
+
+    public static byte[] Respond(RequestResponsePair pair, byte[] request)
+    {
+        var offset = 0;
+        var matches = new Dictionary<string, byte>();
+        var res = new List<byte>();
+        using var requestReader = new StringReader(pair.RequestPattern);
+
+        string line;
+        while ((line = requestReader.ReadLine()) != null)
+        {
+            var tokens = line.Split(Space, StringSplitOptions.RemoveEmptyEntries);
+            foreach (var token in tokens)
+            {
+                if (token.StartsWith(Comment)) break;
+
+                if (offset >= request.Length)
+                {
+                    throw new Exception("Request pattern has more data than request.");
+                }
+
+                var received = request[offset];
+
+                if (token.Length == 2 && byte.TryParse(token, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var value))
+                {
+                    // Number, exact match
+                    if (value != received)
+                    {
+                        throw new Exception($"Incorrect data at offset {offset}. Expected {value:X2}, received {received:X2}.");
+                    }
+                }
+                else
+                {
+                    matches[token] = received;
+                }
+
+                offset++;
+            }
+        }
+
+        if (offset != request.Length) throw new Exception("Request contained more data than request pattern.");
+
+        using var responseReader = new StringReader(pair.ResponsePattern);
+        while ((line = responseReader.ReadLine()) != null)
+        {
+            var tokens = line.Split(Space, StringSplitOptions.RemoveEmptyEntries);
+            foreach (var token in tokens)
+            {
+                if (token.StartsWith(Comment)) break;
+
+                if (token.Length == 2 && byte.TryParse(token, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var value))
+                {
+                    res.Add(value);
+                }
+                else
+                {
+                    if (!matches.TryGetValue(token, out var match))
+                    {
+                        throw new Exception($"Unmatched token '{token}' in response.");
+                    }
+
+                    res.Add(match);
+                }
+            }
+        }
+
+        return res.ToArray();
+    }
+}

S7.Net.UnitTest/PLCAddressParsingTests.cs

@@ -0,0 +1,156 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+using System;
+
+namespace S7.Net.UnitTest
+{
+    [TestClass]
+    public class PLCAddressParsingTests
+    {
+        [TestMethod]
+        public void T01_ParseM2000_1()
+        {
+            DataItem dataItem = DataItem.FromAddress("M2000.1");
+
+            Assert.AreEqual(DataType.Memory, dataItem.DataType, "Wrong datatype for M2000.1");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for M2000.1");
+            Assert.AreEqual(VarType.Bit, dataItem.VarType, "Wrong vartype for M2000.1");
+            Assert.AreEqual(2000, dataItem.StartByteAdr, "Wrong startbyte for M2000.1");
+            Assert.AreEqual(1, dataItem.BitAdr, "Wrong bit for M2000.1");
+        }
+
+        [TestMethod]
+        public void T02_ParseMB200()
+        {
+            DataItem dataItem = DataItem.FromAddress("MB200");
+
+            Assert.AreEqual(DataType.Memory, dataItem.DataType, "Wrong datatype for MB200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for MB200");
+            Assert.AreEqual(VarType.Byte, dataItem.VarType, "Wrong vartype for MB200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for MB200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for MB200");
+        }
+
+        [TestMethod]
+        public void T03_ParseMW200()
+        {
+            DataItem dataItem = DataItem.FromAddress("MW200");
+
+            Assert.AreEqual(DataType.Memory, dataItem.DataType, "Wrong datatype for MW200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for MW200");
+            Assert.AreEqual(VarType.Word, dataItem.VarType, "Wrong vartype for MW200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for MW200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for MW200");
+        }
+
+        [TestMethod]
+        public void T04_ParseMD200()
+        {
+            DataItem dataItem = DataItem.FromAddress("MD200");
+
+            Assert.AreEqual(DataType.Memory, dataItem.DataType, "Wrong datatype for MD200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for MD200");
+            Assert.AreEqual(VarType.DWord, dataItem.VarType, "Wrong vartype for MD200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for MD200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for MD200");
+        }
+
+
+        [TestMethod]
+        public void T05_ParseI2000_1()
+        {
+            DataItem dataItem = DataItem.FromAddress("I2000.1");
+
+            Assert.AreEqual(DataType.Input, dataItem.DataType, "Wrong datatype for I2000.1");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for I2000.1");
+            Assert.AreEqual(VarType.Bit, dataItem.VarType, "Wrong vartype for I2000.1");
+            Assert.AreEqual(2000, dataItem.StartByteAdr, "Wrong startbyte for I2000.1");
+            Assert.AreEqual(1, dataItem.BitAdr, "Wrong bit for I2000.1");
+        }
+
+        [TestMethod]
+        public void T06_ParseIB200()
+        {
+            DataItem dataItem = DataItem.FromAddress("IB200");
+
+            Assert.AreEqual(DataType.Input, dataItem.DataType, "Wrong datatype for IB200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for IB200");
+            Assert.AreEqual(VarType.Byte, dataItem.VarType, "Wrong vartype for IB200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for IB200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for IB200");
+        }
+
+        [TestMethod]
+        public void T07_ParseIW200()
+        {
+            DataItem dataItem = DataItem.FromAddress("IW200");
+
+            Assert.AreEqual(DataType.Input, dataItem.DataType, "Wrong datatype for IW200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for IW200");
+            Assert.AreEqual(VarType.Word, dataItem.VarType, "Wrong vartype for IW200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for IW200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for IW200");
+        }
+
+        [TestMethod]
+        public void T08_ParseID200()
+        {
+            DataItem dataItem = DataItem.FromAddress("ID200");
+
+            Assert.AreEqual(DataType.Input, dataItem.DataType, "Wrong datatype for ID200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for ID200");
+            Assert.AreEqual(VarType.DWord, dataItem.VarType, "Wrong vartype for ID200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for ID200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for ID200");
+        }
+
+
+        [TestMethod]
+        public void T09_ParseQ2000_1()
+        {
+            DataItem dataItem = DataItem.FromAddress("Q2000.1");
+
+            Assert.AreEqual(DataType.Output, dataItem.DataType, "Wrong datatype for Q2000.1");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for Q2000.1");
+            Assert.AreEqual(VarType.Bit, dataItem.VarType, "Wrong vartype for Q2000.1");
+            Assert.AreEqual(2000, dataItem.StartByteAdr, "Wrong startbyte for Q2000.1");
+            Assert.AreEqual(1, dataItem.BitAdr, "Wrong bit for Q2000.1");
+        }
+
+        [TestMethod]
+        public void T10_ParseQB200()
+        {
+            DataItem dataItem = DataItem.FromAddress("QB200");
+
+            Assert.AreEqual(DataType.Output, dataItem.DataType, "Wrong datatype for QB200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for QB200");
+            Assert.AreEqual(VarType.Byte, dataItem.VarType, "Wrong vartype for QB200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for QB200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for QB200");
+        }
+
+        [TestMethod]
+        public void T11_ParseQW200()
+        {
+            DataItem dataItem = DataItem.FromAddress("QW200");
+
+            Assert.AreEqual(DataType.Output, dataItem.DataType, "Wrong datatype for QW200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for QW200");
+            Assert.AreEqual(VarType.Word, dataItem.VarType, "Wrong vartype for QW200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for QW200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for QW200");
+        }
+
+        [TestMethod]
+        public void T12_ParseQD200()
+        {
+            DataItem dataItem = DataItem.FromAddress("QD200");
+
+            Assert.AreEqual(DataType.Output, dataItem.DataType, "Wrong datatype for QD200");
+            Assert.AreEqual(0, dataItem.DB, "Wrong dbnumber for QD200");
+            Assert.AreEqual(VarType.DWord, dataItem.VarType, "Wrong vartype for QD200");
+            Assert.AreEqual(200, dataItem.StartByteAdr, "Wrong startbyte for QD200");
+            Assert.AreEqual(0, dataItem.BitAdr, "Wrong bit for QD200");
+        }
+    }
+}

S7.Net.UnitTest/Properties/AssemblyInfo.cs

@@ -1,36 +0,0 @@
-using System.Reflection;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-
-// General Information about an assembly is controlled through the following 
-// set of attributes. Change these attribute values to modify the information
-// associated with an assembly.
-[assembly: AssemblyTitle("S7.Net.UnitTest")]
-[assembly: AssemblyDescription("")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("")]
-[assembly: AssemblyProduct("S7Net.UnitTest")]
-[assembly: AssemblyCopyright("Copyright ©  2014")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-
-// Setting ComVisible to false makes the types in this assembly not visible 
-// to COM components.  If you need to access a type in this assembly from 
-// COM, set the ComVisible attribute to true on that type.
-[assembly: ComVisible(false)]
-
-// The following GUID is for the ID of the typelib if this project is exposed to COM
-[assembly: Guid("6f73e1b1-301b-471e-9f38-3dcbddbcfc21")]
-
-// Version information for an assembly consists of the following four values:
-//
-//      Major Version
-//      Minor Version 
-//      Build Number
-//      Revision
-//
-// You can specify all the values or you can default the Build and Revision Numbers 
-// by using the '*' as shown below:
-// [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]

S7.Net.UnitTest/ProtocolTests.cs

@@ -0,0 +1,85 @@
+using System;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Protocol;
+
+namespace S7.Net.UnitTest
+{
+    [TestClass]
+    public class ProtocolUnitTest
+    {
+        public TestContext TestContext { get; set; }
+
+        [TestMethod]
+        public async Task TPKT_Read()
+        {
+            var m = new MemoryStream(StringToByteArray("0300002902f0803203000000010002001400000401ff0400807710000100000103000000033f8ccccd"));
+            var t = await TPKT.ReadAsync(m, TestContext.CancellationTokenSource.Token);
+            Assert.AreEqual(0x03, t.Version);
+            Assert.AreEqual(0x29, t.Length);
+        }
+
+        [TestMethod]
+        [ExpectedException(typeof(TPKTInvalidException))]
+        public async Task TPKT_ReadShort()
+        {
+            var m = new MemoryStream(StringToByteArray("0300002902f0803203000000010002001400000401ff040080"));
+            var t = await TPKT.ReadAsync(m, CancellationToken.None);
+        }
+
+
+        [TestMethod]
+        [ExpectedException(typeof(TPKTInvalidException))]
+        public async Task TPKT_ReadShortAsync()
+        {
+            var m = new MemoryStream(StringToByteArray("0300002902f0803203000000010002001400000401ff040080"));
+            var t = await TPKT.ReadAsync(m, TestContext.CancellationTokenSource.Token);
+        }
+
+        [TestMethod]
+        public async Task COTP_ReadTSDU()
+        {
+            var expected = StringToByteArray("320700000400000800080001120411440100ff09000400000000");
+            var m = new MemoryStream(StringToByteArray("0300000702f0000300000702f0000300002102f080320700000400000800080001120411440100ff09000400000000"));
+            var t = await COTP.TSDU.ReadAsync(m, TestContext.CancellationTokenSource.Token);
+            Assert.IsTrue(expected.SequenceEqual(t));
+        }
+
+        public static byte[] StringToByteArray(string hex)
+        {
+            return Enumerable.Range(0, hex.Length)
+                             .Where(x => x % 2 == 0)
+                             .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
+                             .ToArray();
+        }
+
+
+        [TestMethod]
+        public async Task TestResponseCode()
+        {
+            var expected = StringToByteArray("320700000400000800080001120411440100ff09000400000000");
+            var m = new MemoryStream(StringToByteArray("0300000702f0000300000702f0000300002102f080320700000400000800080001120411440100ff09000400000000"));
+            var t = await COTP.TSDU.ReadAsync(m, CancellationToken.None);
+            Assert.IsTrue(expected.SequenceEqual(t));
+
+            // Test all possible byte values. Everything except 0xff should throw an exception.
+            var testData = Enumerable.Range(0, 256).Select(i => new { StatusCode = (ReadWriteErrorCode)i, ThrowsException = i != (byte)ReadWriteErrorCode.Success });
+
+            foreach (var entry in testData)
+            {
+                if (entry.ThrowsException)
+                {
+                    Assert.ThrowsException<Exception>(() => Plc.ValidateResponseCode(entry.StatusCode));
+                }
+                else
+                {
+                    Plc.ValidateResponseCode(entry.StatusCode);
+                }
+            }
+        }
+    }
+
+}

S7.Net.UnitTest/S7.Net.UnitTest.csproj

@@ -1,108 +1,42 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup Condition=" '$(OS)' != 'Windows_NT' ">
+    <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(OS)' == 'Windows_NT' "> 
+    <TargetFrameworks>net6.0;net7.0;net462</TargetFrameworks>
+  </PropertyGroup>
+
   <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{303CCED6-9ABC-4899-A509-743341AAA804}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>S7.UnitTest</RootNamespace>
-    <AssemblyName>S7Net.UnitTest</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
-    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
-    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
-    <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\$(VisualStudioVersion)\UITestExtensionPackages</ReferencePath>
-    <IsCodedUITest>False</IsCodedUITest>
-    <TestProjectType>UnitTest</TestProjectType>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
+    <LangVersion>latest</LangVersion>
+    <SignAssembly>true</SignAssembly>
+    <AssemblyOriginatorKeyFile>Properties\S7.Net.snk</AssemblyOriginatorKeyFile>
+    <IsPackable>false</IsPackable>
+    <Copyright>Copyright ©  2014</Copyright>
+    <PlatformTarget>x64</PlatformTarget>
   </PropertyGroup>
+  
   <ItemGroup>
-    <Reference Include="System" />
-    <Reference Include="System.ServiceProcess" />
-    <Reference Include="System.Windows.Forms" />
+    <PackageReference Include="GitHubActionsTestLogger" Version="2.3.2">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.7.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="2.1.2" />
+    <PackageReference Include="MSTest.TestFramework" Version="2.1.2" />
+    <PackageReference Include="coverlet.collector" Version="1.3.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
-  <Choose>
-    <When Condition="('$(VisualStudioVersion)' == '10.0' or '$(VisualStudioVersion)' == '') and '$(TargetFrameworkVersion)' == 'v3.5'">
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework, Version=10.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
-      </ItemGroup>
-    </When>
-    <Otherwise>
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" />
-      </ItemGroup>
-    </Otherwise>
-  </Choose>
+
   <ItemGroup>
-    <Compile Include="ConvertersUnitTest.cs" />
-    <Compile Include="Helpers\ConsoleManager.cs" />
-    <Compile Include="Helpers\NativeMethods.cs" />
-    <Compile Include="Helpers\S7TestServer.cs" />
-    <Compile Include="Helpers\TestClassWithArrays.cs" />
-    <Compile Include="Helpers\TestClassWithCustomType.cs" />
-    <Compile Include="Helpers\TestClassWithPrivateSetters.cs" />
-    <Compile Include="Helpers\TestLongClass.cs" />
-    <Compile Include="Snap7\snap7.net.cs" />
-    <Compile Include="Helpers\TestClass.cs" />
-    <Compile Include="Helpers\TestStruct.cs" />
-    <Compile Include="S7NetTests.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Helpers\TestLongStruct.cs" />
+    <ProjectReference Include="..\S7.Net\S7.Net.csproj" />
   </ItemGroup>
+
   <ItemGroup>
-    <Content Include="snap7.dll">
+    <None Update="runtimes\win-x64\native\snap7.dll" Link="snap7.dll">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-    </Content>
+    </None>
   </ItemGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\S7.Net\S7.Net.csproj">
-      <Project>{bfd484f9-3f04-42a2-bf2a-60a189a25dcf}</Project>
-      <Name>S7.Net</Name>
-    </ProjectReference>
-  </ItemGroup>
-  <Choose>
-    <When Condition="'$(VisualStudioVersion)' == '10.0' And '$(IsCodedUITest)' == 'True'">
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.CodedUITestFramework, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Extension, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITesting, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-      </ItemGroup>
-    </When>
-  </Choose>
-  <Import Project="$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets" Condition="Exists('$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets')" />
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
-</Project>
+</Project>

S7.Net.UnitTest/S7NetTestsSync.cs

@@ -1,14 +1,15 @@
 #region Using
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using S7.Net;
 using S7.Net.UnitTest.Helpers;
-using S7.Net.UnitTest;
-using System.ServiceProcess;
 using S7.Net.Types;
 using S7.UnitTest.Helpers;
+using System.Security.Cryptography;
+
+#if NET5_0_OR_GREATER
+using System.Buffers;
+#endif
 
 #endregion
 
@@ -30,13 +31,19 @@ using S7.UnitTest.Helpers;
  * server has problems.
  *
  */
+
+//This file contains tests for the synchronous methods
+#pragma warning disable CS0618
 namespace S7.Net.UnitTest
 {
     [TestClass]
-    public class S7NetTests
+    public partial class S7NetTests : IDisposable
     {
         #region Constants
         const int DB2 = 2;
+        const int DB4 = 4;
+        const short TestServerPort = 31122;
+        const string TestServerIp = "127.0.0.1";
         #endregion
 
         #region Private fields
@@ -49,16 +56,19 @@ namespace S7.Net.UnitTest
         /// </summary>
         public S7NetTests()
         {
-            plc = new Plc(CpuType.S7300, "127.0.0.1", 0, 2);
-            //ConsoleManager.Show();
-            ShutDownServiceS7oiehsx64();
+            plc = CreatePlc();
 
         }
 
+        private static Plc CreatePlc()
+        {
+            return new Plc(CpuType.S7300, TestServerIp, TestServerPort, 0, 2);
+        }
+
         [TestInitialize]
         public void Setup()
         {
-            S7TestServer.Start();
+            S7TestServer.Start(TestServerPort);
             plc.Open();
         }
 
@@ -78,8 +88,14 @@ namespace S7.Net.UnitTest
         {
             if (plc.IsConnected == false)
             {
-                var error = plc.Open();
-                Assert.AreEqual(ErrorCode.NoError, error, "If you have s7 installed you must close s7oiehsx64 service.");
+                try
+                {
+                    plc.Open();
+                }
+                catch (Exception e)
+                {
+                    throw new Exception("If you have s7 installed you must close s7oiehsx64 service.", e);
+                }
             }
         }
 
@@ -136,19 +152,24 @@ namespace S7.Net.UnitTest
 
         /// <summary>
         /// Read/Write a single REAL with a single request.
-        /// Test that writing a double and reading it gives the correct value.
+        /// Test that writing a float and reading it gives the correct value.
         /// </summary>
         [TestMethod]
         public void T03_WriteAndReadRealVariables()
         {
             Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
 
-            // Reading and writing a double is quite complicated, because it needs to be converted to DWord before the write,
-            // then reconvert to double after the read.
-            double val = 35.687;
-            plc.Write("DB1.DBD40", val.ConvertToUInt());
-            double result = ((uint)plc.Read("DB1.DBD40")).ConvertToDouble();
-            Assert.AreEqual(val, Math.Round(result, 3)); // float lose precision, so i need to round it
+            // Reading and writing a float is quite complicated, because it needs to be converted to DWord before the write,
+            // then reconvert to float after the read. Float values can contain only 7 digits, so no precision is lost.
+            float val2 = 1234567;
+            plc.Write("DB1.DBD40", val2.ConvertToUInt());
+            float result2 = ((uint)plc.Read("DB1.DBD40")).ConvertToFloat();
+            Assert.AreEqual(val2, result2);
+
+            float val3 = 12.34567f;
+            plc.Write("DB1.DBD40", val3.ConvertToUInt());
+            float result3 = ((uint)plc.Read("DB1.DBD40")).ConvertToFloat();
+            Assert.AreEqual(val3, result3);
         }
 
         /// <summary>
@@ -164,8 +185,12 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
+
             plc.WriteClass(tc, DB2);
             TestClass tc2 = new TestClass();
             // Values that are read from a class are stored inside the class itself, that is passed by reference
@@ -174,8 +199,11 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc.BitVariable10, tc2.BitVariable10);
             Assert.AreEqual(tc.DIntVariable, tc2.DIntVariable);
             Assert.AreEqual(tc.IntVariable, tc2.IntVariable);
-            Assert.AreEqual(tc.RealVariable, Math.Round(tc2.RealVariable, 3));
+            Assert.AreEqual(tc.LRealVariable, tc2.LRealVariable);
+            Assert.AreEqual(tc.RealVariable, tc2.RealVariable);
             Assert.AreEqual(tc.DWordVariable, tc2.DWordVariable);
+            Assert.AreEqual(tc.WStringVariable, tc2.WStringVariable);
+            Assert.AreEqual(tc.StringVariable, tc2.StringVariable);
         }
 
         /// <summary>
@@ -191,8 +219,12 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
+
             plc.WriteStruct(tc, DB2);
             // Values that are read from a struct are stored in a new struct, returned by the funcion ReadStruct
             TestStruct tc2 = (TestStruct)plc.ReadStruct(typeof(TestStruct), DB2);
@@ -200,8 +232,11 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc.BitVariable10, tc2.BitVariable10);
             Assert.AreEqual(tc.DIntVariable, tc2.DIntVariable);
             Assert.AreEqual(tc.IntVariable, tc2.IntVariable);
-            Assert.AreEqual(tc.RealVariable, Math.Round(tc2.RealVariable, 3));
+            Assert.AreEqual(tc.LRealVariable, tc2.LRealVariable);
+            Assert.AreEqual(tc.RealVariable, tc2.RealVariable);
             Assert.AreEqual(tc.DWordVariable, tc2.DWordVariable);
+            Assert.AreEqual(tc.WStringVariable, tc2.WStringVariable);
+            Assert.AreEqual(tc.StringVariable, tc2.StringVariable);
         }
 
         /// <summary>
@@ -238,30 +273,28 @@ namespace S7.Net.UnitTest
             tc.IntVariable110 = 200;
             tc.IntVariable111 = 201;
             plc.WriteStruct(tc, DB2);
-            Assert.AreEqual(ErrorCode.NoError, plc.LastErrorCode);
             // Values that are read from a struct are stored in a new struct, returned by the funcion ReadStruct
             TestLongStruct tc2 = (TestLongStruct)plc.ReadStruct(typeof(TestLongStruct), DB2);
-            Assert.AreEqual(ErrorCode.NoError, plc.LastErrorCode);
-            Assert.AreEqual( tc.IntVariable0,     tc2.IntVariable0 );
-            Assert.AreEqual( tc.IntVariable1,     tc2.IntVariable1 );
-            Assert.AreEqual( tc.IntVariable10, tc2.IntVariable10);
-            Assert.AreEqual( tc.IntVariable11, tc2.IntVariable11);
-            Assert.AreEqual( tc.IntVariable20, tc2.IntVariable20);
-            Assert.AreEqual( tc.IntVariable21, tc2.IntVariable21);
-            Assert.AreEqual( tc.IntVariable30, tc2.IntVariable30);
-            Assert.AreEqual( tc.IntVariable31, tc2.IntVariable31);
-            Assert.AreEqual( tc.IntVariable40, tc2.IntVariable40);
-            Assert.AreEqual( tc.IntVariable41, tc2.IntVariable41);
-            Assert.AreEqual( tc.IntVariable50, tc2.IntVariable50);
-            Assert.AreEqual( tc.IntVariable51, tc2.IntVariable51);
-            Assert.AreEqual( tc.IntVariable60, tc2.IntVariable60);
-            Assert.AreEqual( tc.IntVariable61, tc2.IntVariable61);
-            Assert.AreEqual( tc.IntVariable70, tc2.IntVariable70);
-            Assert.AreEqual( tc.IntVariable71, tc2.IntVariable71);
-            Assert.AreEqual( tc.IntVariable80, tc2.IntVariable80);
-            Assert.AreEqual( tc.IntVariable81, tc2.IntVariable81);
-            Assert.AreEqual( tc.IntVariable90, tc2.IntVariable90);
-            Assert.AreEqual(tc.IntVariable91,  tc2.IntVariable91);
+            Assert.AreEqual(tc.IntVariable0, tc2.IntVariable0);
+            Assert.AreEqual(tc.IntVariable1, tc2.IntVariable1);
+            Assert.AreEqual(tc.IntVariable10, tc2.IntVariable10);
+            Assert.AreEqual(tc.IntVariable11, tc2.IntVariable11);
+            Assert.AreEqual(tc.IntVariable20, tc2.IntVariable20);
+            Assert.AreEqual(tc.IntVariable21, tc2.IntVariable21);
+            Assert.AreEqual(tc.IntVariable30, tc2.IntVariable30);
+            Assert.AreEqual(tc.IntVariable31, tc2.IntVariable31);
+            Assert.AreEqual(tc.IntVariable40, tc2.IntVariable40);
+            Assert.AreEqual(tc.IntVariable41, tc2.IntVariable41);
+            Assert.AreEqual(tc.IntVariable50, tc2.IntVariable50);
+            Assert.AreEqual(tc.IntVariable51, tc2.IntVariable51);
+            Assert.AreEqual(tc.IntVariable60, tc2.IntVariable60);
+            Assert.AreEqual(tc.IntVariable61, tc2.IntVariable61);
+            Assert.AreEqual(tc.IntVariable70, tc2.IntVariable70);
+            Assert.AreEqual(tc.IntVariable71, tc2.IntVariable71);
+            Assert.AreEqual(tc.IntVariable80, tc2.IntVariable80);
+            Assert.AreEqual(tc.IntVariable81, tc2.IntVariable81);
+            Assert.AreEqual(tc.IntVariable90, tc2.IntVariable90);
+            Assert.AreEqual(tc.IntVariable91, tc2.IntVariable91);
             Assert.AreEqual(tc.IntVariable100, tc2.IntVariable100);
             Assert.AreEqual(tc.IntVariable101, tc2.IntVariable101);
             Assert.AreEqual(tc.IntVariable110, tc2.IntVariable110);
@@ -302,11 +335,9 @@ namespace S7.Net.UnitTest
             tc.IntVariable110 = 200;
             tc.IntVariable111 = 201;
             plc.WriteClass(tc, DB2);
-            Assert.AreEqual(ErrorCode.NoError, plc.LastErrorCode);
             // Values that are read from a struct are stored in a new struct, returned by the funcion ReadStruct
             TestLongClass tc2 = new TestLongClass();
             plc.ReadClass(tc2, DB2);
-            Assert.AreEqual(ErrorCode.NoError, plc.LastErrorCode);
             Assert.AreEqual(tc.IntVariable0, tc2.IntVariable0);
             Assert.AreEqual(tc.IntVariable1, tc2.IntVariable1);
             Assert.AreEqual(tc.IntVariable10, tc2.IntVariable10);
@@ -386,19 +417,51 @@ namespace S7.Net.UnitTest
         {
             Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
 
-            ushort val = 16384;
-            plc.Write("DB2.DBW16384", val);
-            ushort result = (ushort)plc.Read("DB2.DBW16384");
-            Assert.AreEqual(val, result, "A ushort goes from 0 to 64512");
+            bool val = true;
+            plc.Write("DB2.DBX0.5", val);
+            bool result = (bool)plc.Read("DB2.DBX0.5");
+            Assert.AreEqual(val, result);
 
-            ushort val2 = 129;
-            plc.Write("DB2.DBW16", val2);
-            ushort result2 = (ushort)plc.Read("DB2.DBW16");
-            Assert.AreEqual(val2, result2, "A ushort goes from 0 to 64512");
+            ushort val1 = 16384;
+            plc.Write("DB2.DBW16384", val1);
+            ushort result1 = (ushort)plc.Read("DB2.DBW16384");
+            Assert.AreEqual(val1, result1, "A ushort goes from 0 to 64512");
+
+            bool val2 = true;
+            plc.Write("DB2.DBX8192.7", val2);
+            bool result2 = (bool)plc.Read("DB2.DBX8192.7");
+            Assert.AreEqual(val2, result2);
+
+            ushort val3 = 129;
+            plc.Write("DB2.DBW16", val3);
+            ushort result3 = (ushort)plc.Read("DB2.DBW16");
+            Assert.AreEqual(val3, result3, "A ushort goes from 0 to 64512");
+
+            byte[] val4 = new byte[] { 0x12, 0x34 };
+            plc.Write("DB2.DBB2048", val4[0]);
+            plc.Write("DB2.DBB2049", val4[1]);
+            byte result4b0 = (byte)plc.Read("DB2.DBB2048");
+            byte result4b1 = (byte)plc.Read("DB2.DBB2049");
+            Assert.AreEqual(val4[0], result4b0);
+            Assert.AreEqual(val4[1], result4b1);
+
+            bool val6 = true;
+            plc.Write("DB2.DBX16384.6", val6);
+            bool result6 = (bool)plc.Read("DB2.DBX16384.6");
+            Assert.AreEqual(val6, result6);
 
             var dataItems = new List<DataItem>()
             {
                 new DataItem
+                {
+                    Count = 1,
+                    DataType = DataType.DataBlock,
+                    DB = 2,
+                    StartByteAdr = 0,
+                    BitAdr = 5,
+                    VarType = VarType.Bit
+                }
+                ,new DataItem
                 {
                     Count = 1,
                     DataType = DataType.DataBlock,
@@ -407,19 +470,61 @@ namespace S7.Net.UnitTest
                     VarType = VarType.Word
                 },
                 new DataItem
+                {
+                    Count = 1,
+                    DataType = DataType.DataBlock,
+                    DB = 2,
+                    StartByteAdr = 8192,
+                    BitAdr = 7,
+                    VarType = VarType.Bit
+                },
+                new DataItem
                 {
                     Count = 1,
                     DataType = DataType.DataBlock,
                     DB = 2,
                     StartByteAdr = 16,
                     VarType = VarType.Word
-                }
+                },
+                // single byte
+                new DataItem
+                {
+                    Count = 1,
+                    DataType = DataType.DataBlock,
+                    DB = 2,
+                    StartByteAdr = 2048,
+                    VarType = VarType.Byte
+                },
+                // multiple bytes
+                new DataItem
+                {
+                    Count = 2,
+                    DataType = DataType.DataBlock,
+                    DB = 2,
+                    StartByteAdr = 2048,
+                    VarType = VarType.Byte
+                },
+                new DataItem
+                {
+                    Count = 1,
+                    DataType = DataType.DataBlock,
+                    DB = 2,
+                    StartByteAdr = 16384,
+                    BitAdr = 6,
+                    VarType = VarType.Bit
+                },
             };
 
             plc.ReadMultipleVars(dataItems);
 
             Assert.AreEqual(dataItems[0].Value, val);
-            Assert.AreEqual(dataItems[1].Value, val2);
+            Assert.AreEqual(dataItems[1].Value, val1);
+            Assert.AreEqual(dataItems[2].Value, val2);
+            Assert.AreEqual(dataItems[3].Value, val3);
+            Assert.AreEqual(dataItems[4].Value, val4[0]);
+            Assert.AreEqual(((byte[])dataItems[5].Value)[0], val4[0]);  //dataItem[5].Value should be byte[2]
+            Assert.AreEqual(((byte[])dataItems[5].Value)[1], val4[1]);
+            Assert.AreEqual(dataItems[6].Value, val6);
         }
 
         /// <summary>
@@ -479,8 +584,11 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
 
             plc.WriteClass(tc, DB2);
 
@@ -491,7 +599,8 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc.BitVariable10, tc2.BitVariable10);
             Assert.AreEqual(tc.DIntVariable, tc2.DIntVariable);
             Assert.AreEqual(tc.IntVariable, tc2.IntVariable);
-            Assert.AreEqual(tc.RealVariable, Math.Round(tc2.RealVariable, 3));
+            Assert.AreEqual(tc.LRealVariable, tc2.LRealVariable);
+            Assert.AreEqual(tc.RealVariable, tc2.RealVariable);
             Assert.AreEqual(tc.DWordVariable, tc2.DWordVariable);
 
             Assert.AreEqual(TestClassWithPrivateSetters.PRIVATE_SETTER_VALUE, tc2.PrivateSetterProperty);
@@ -501,19 +610,14 @@ namespace S7.Net.UnitTest
         }
 
 
-        [TestMethod]
-        public void T13_ReadBytesReturnsEmptyArrayIfPlcIsNotConnected()
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T13_ReadBytesThrowsIfPlcIsNotConnected()
         {
             using (var notConnectedPlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 0))
             {
                 Assert.IsFalse(notConnectedPlc.IsConnected);
-
-                int expectedReadBytes = 0; // 0 bytes, because no connection was established
-
                 TestClass tc = new TestClass();
                 int actualReadBytes = notConnectedPlc.ReadClass(tc, DB2);
-
-                Assert.AreEqual(expectedReadBytes, actualReadBytes);
             }
         }
 
@@ -527,8 +631,11 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
 
             plc.WriteClass(tc, DB2);
 
@@ -541,12 +648,15 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc2.BitVariable10, tc2Generic.BitVariable10);
             Assert.AreEqual(tc2.DIntVariable, tc2Generic.DIntVariable);
             Assert.AreEqual(tc2.IntVariable, tc2Generic.IntVariable);
-            Assert.AreEqual(Math.Round(tc2.RealVariable, 3), Math.Round(tc2Generic.RealVariable, 3));
+            Assert.AreEqual(Math.Round(tc2.LRealVariable, 3), Math.Round(tc2Generic.LRealVariable, 3));
+            Assert.AreEqual(tc2.RealVariable, tc2Generic.RealVariable);
             Assert.AreEqual(tc2.DWordVariable, tc2Generic.DWordVariable);
+            Assert.AreEqual(tc2.WStringVariable, tc2Generic.WStringVariable);
+            Assert.AreEqual(tc2.StringVariable, tc2Generic.StringVariable);
         }
 
-        [TestMethod]
-        public void T15_ReadClassWithGenericReturnsNullIfPlcIsNotConnected()
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T15_ReadClassWithGenericThrowsIfPlcIsNotConnected()
         {
             using (var notConnectedPlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 0))
             {
@@ -568,8 +678,11 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
 
             plc.WriteClass(tc, DB2);
 
@@ -581,12 +694,15 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc2Generic.BitVariable10, tc2GenericWithClassFactory.BitVariable10);
             Assert.AreEqual(tc2Generic.DIntVariable, tc2GenericWithClassFactory.DIntVariable);
             Assert.AreEqual(tc2Generic.IntVariable, tc2GenericWithClassFactory.IntVariable);
-            Assert.AreEqual(Math.Round(tc2Generic.RealVariable, 3), Math.Round(tc2GenericWithClassFactory.RealVariable, 3));
+            Assert.AreEqual(Math.Round(tc2Generic.LRealVariable, 3), Math.Round(tc2GenericWithClassFactory.LRealVariable, 3));
+            Assert.AreEqual(tc2Generic.RealVariable, tc2GenericWithClassFactory.RealVariable);
             Assert.AreEqual(tc2Generic.DWordVariable, tc2GenericWithClassFactory.DWordVariable);
+            Assert.AreEqual(tc2Generic.WStringVariable, tc2GenericWithClassFactory.WStringVariable);
+            Assert.AreEqual(tc2Generic.StringVariable, tc2GenericWithClassFactory.StringVariable);
         }
 
-        [TestMethod]
-        public void T17_ReadClassWithGenericAndClassFactoryReturnsNullIfPlcIsNotConnected()
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T17_ReadClassWithGenericAndClassFactoryThrowsIfPlcIsNotConnected()
         {
             using (var notConnectedPlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 0))
             {
@@ -599,7 +715,102 @@ namespace S7.Net.UnitTest
         }
 
         [TestMethod]
-        public void T18_ReadStructReturnsNullIfPlcIsNotConnected()
+        public void T31_ReadClassWithNestedClassAfterBit()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            Assert.AreEqual(6, Types.Class.GetClassSize(new TestClassWithNestedClass()));
+
+            TestClassWithNestedClass tc = new TestClassWithNestedClass();
+            tc.BitVariable00 = true;
+            tc.BitVariable01.BitVariable00 = true;
+            tc.ByteVariable02.ByteVariable00 = 128;
+            tc.BitVariable03 = true;
+            tc.ShortVariable04.ShortVarialbe00 = -15000;
+
+            TestClassWithNestedClass tc2 = new TestClassWithNestedClass();
+            plc.ReadClass(tc2, DB4);
+            Assert.AreEqual(tc.BitVariable00, tc2.BitVariable00);
+            Assert.AreEqual(tc.BitVariable01.BitVariable00, tc2.BitVariable01.BitVariable00);
+            Assert.AreEqual(tc.ByteVariable02.ByteVariable00, tc2.ByteVariable02.ByteVariable00);
+            Assert.AreEqual(tc.BitVariable03, tc2.BitVariable03);
+            Assert.AreEqual(tc.ShortVariable04.ShortVarialbe00, tc2.ShortVariable04.ShortVarialbe00);
+        }
+
+        [TestMethod]
+        public void T32_ReadAndWriteNestedClass()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            TestClassWithNestedClass tc = new TestClassWithNestedClass
+            {
+                BitVariable00 = true,
+                BitVariable01 = new TestClassInnerWithBool { BitVariable00 = true },
+                ByteVariable02 = new TestClassInnerWithByte { ByteVariable00 = 128 },
+                BitVariable03 = true,
+                ShortVariable04 = new TestClassInnerWithShort { ShortVarialbe00 = -15000 }
+            };
+
+            plc.WriteClass(tc, DB4);
+            TestClassWithNestedClass tc2 = new TestClassWithNestedClass();
+            // Values that are read from a class are stored inside the class itself, that is passed by reference
+            plc.ReadClass(tc2, DB4);
+            Assert.AreEqual(tc.BitVariable00, tc2.BitVariable00);
+            Assert.AreEqual(tc.BitVariable01.BitVariable00, tc2.BitVariable01.BitVariable00);
+            Assert.AreEqual(tc.ByteVariable02.ByteVariable00, tc2.ByteVariable02.ByteVariable00);
+            Assert.AreEqual(tc.BitVariable03, tc2.BitVariable03);
+            Assert.AreEqual(tc.ShortVariable04.ShortVarialbe00, tc2.ShortVariable04.ShortVarialbe00);
+        }
+
+        /// <summary>
+        /// Write/Read a large amount of data to test PDU max
+        /// </summary>
+        [TestMethod]
+        public void T33_WriteLargeByteArray()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            var randomEngine = new Random();
+            var data = new byte[8192];
+            var db = 2;
+            randomEngine.NextBytes(data);
+
+            plc.WriteBytes(DataType.DataBlock, db, 0, data);
+
+            var readData = plc.ReadBytes(DataType.DataBlock, db, 0, data.Length);
+
+            CollectionAssert.AreEqual(data, readData);
+        }
+
+#if NET5_0_OR_GREATER
+
+        /// <summary>
+        /// Write/Read a large amount of data to test PDU max
+        /// </summary>
+        [TestMethod]
+        public void T33_WriteLargeByteArrayWithSpan()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            var randomEngine = new Random();
+            using var dataOwner = MemoryPool<byte>.Shared.Rent(8192);
+            var data = dataOwner.Memory.Span.Slice(0, 8192);
+            var db = 2;
+            randomEngine.NextBytes(data);
+
+            plc.WriteBytes(DataType.DataBlock, db, 0, data);
+
+            using var readDataOwner = MemoryPool<byte>.Shared.Rent(data.Length);
+            var readData = readDataOwner.Memory.Span.Slice(0, data.Length);
+            plc.ReadBytes(readData, DataType.DataBlock, db, 0);
+
+            CollectionAssert.AreEqual(data.ToArray(), readData.ToArray());
+        }
+
+#endif
+
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T18_ReadStructThrowsIfPlcIsNotConnected()
         {
             using (var notConnectedPlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 0))
             {
@@ -621,8 +832,11 @@ namespace S7.Net.UnitTest
             ts.BitVariable10 = true;
             ts.DIntVariable = -100000;
             ts.IntVariable = -15000;
-            ts.RealVariable = -154.789;
+            ts.LRealVariable = -154.789;
+            ts.RealVariable = -154.789f;
             ts.DWordVariable = 850;
+            ts.WStringVariable = "ÄÜÉÊéà";
+            ts.StringVariable = "Hallo";
 
             plc.WriteStruct(ts, DB2);
 
@@ -634,12 +848,15 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(ts2.BitVariable10, ts2Generic.BitVariable10);
             Assert.AreEqual(ts2.DIntVariable, ts2Generic.DIntVariable);
             Assert.AreEqual(ts2.IntVariable, ts2Generic.IntVariable);
-            Assert.AreEqual(Math.Round(ts2.RealVariable, 3), Math.Round(ts2Generic.RealVariable, 3));
+            Assert.AreEqual(ts2.LRealVariable, ts2Generic.LRealVariable);
+            Assert.AreEqual(ts2.RealVariable, ts2Generic.RealVariable);
             Assert.AreEqual(ts2.DWordVariable, ts2Generic.DWordVariable);
+            Assert.AreEqual(ts2.WStringVariable, ts2Generic.WStringVariable);
+            Assert.AreEqual(ts2.StringVariable, ts2Generic.StringVariable);
         }
 
-        [TestMethod]
-        public void T20_ReadStructWithGenericReturnsNullIfPlcIsNotConnected()
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T20_ReadStructThrowsIfPlcIsNotConnected()
         {
             using (var notConnectedPlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 0))
             {
@@ -664,11 +881,15 @@ namespace S7.Net.UnitTest
             tc.BitVariable10 = true;
             tc.DIntVariable = -100000;
             tc.IntVariable = -15000;
-            tc.RealVariable = -154.789;
+            tc.LRealVariable = -154.789;
+            tc.RealVariable = -154.789f;
             tc.DWordVariable = 850;
+            tc.WStringVariable = "ÄÜÉÊéà";
+            tc.StringVariable = "Hallo";
+
             plc.WriteClass(tc, DB2);
 
-            int expectedReadBytes = Types.Class.GetClassSize(tc);
+            int expectedReadBytes = (int)Types.Class.GetClassSize(tc);
 
             TestClass tc2 = new TestClass();
             // Values that are read from a class are stored inside the class itself, that is passed by reference
@@ -676,7 +897,7 @@ namespace S7.Net.UnitTest
 
             Assert.AreEqual(expectedReadBytes, actualReadBytes);
         }
-        
+
         [TestMethod]
         public void T22_ReadClassWithArray()
         {
@@ -694,6 +915,9 @@ namespace S7.Net.UnitTest
             tc.Double = float.MinValue;
             tc.Doubles[0] = float.MinValue + 1;
             tc.Doubles[1] = float.MaxValue;
+            tc.Single = float.MinValue;
+            tc.Singles[0] = float.MinValue + 1;
+            tc.Singles[1] = float.MaxValue;
             tc.UShort = ushort.MinValue + 1;
             tc.UShorts[0] = ushort.MinValue + 1;
             tc.UShorts[1] = ushort.MaxValue;
@@ -717,6 +941,10 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc.Doubles[0], tc2.Doubles[0]);
             Assert.AreEqual(tc.Doubles[1], tc2.Doubles[1]);
 
+            Assert.AreEqual(tc.Single, tc2.Single);
+            Assert.AreEqual(tc.Singles[0], tc2.Singles[0]);
+            Assert.AreEqual(tc.Singles[1], tc2.Singles[1]);
+
             Assert.AreEqual(tc.UShort, tc2.UShort);
             Assert.AreEqual(tc.UShorts[0], tc2.UShorts[0]);
             Assert.AreEqual(tc.UShorts[1], tc2.UShorts[1]);
@@ -755,7 +983,14 @@ namespace S7.Net.UnitTest
             S7TestServer.Stop();
 
             var unreachablePlc = new Plc(CpuType.S7300, "255.255.255.255", 0, 2);
-            Assert.IsFalse(unreachablePlc.IsAvailable);
+            try
+            {
+                unreachablePlc.Open();
+            }
+            catch
+            {
+            }
+            Assert.IsFalse(unreachablePlc.IsConnected);
         }
 
         [TestMethod]
@@ -763,31 +998,163 @@ namespace S7.Net.UnitTest
         {
             plc.Close();
             S7TestServer.Stop();
-            S7TestServer.Start();
+            S7TestServer.Start(TestServerPort);
 
-            var reachablePlc = new Plc(CpuType.S7300, "127.0.0.1", 0, 2);
-            Assert.IsTrue(reachablePlc.IsAvailable);
+            var reachablePlc = CreatePlc();
+            reachablePlc.Open();
+            Assert.IsTrue(reachablePlc.IsConnected);
         }
 
-        #endregion
+        [TestMethod]
+        public void T26_ReadWriteDouble()
+        {
+            double test_value = 55.66;
+            plc.Write(DataType.DataBlock, 1, 0, test_value);
+            var result = (double)plc.Read(DataType.DataBlock, 1, 0, VarType.LReal, 1);
+
+            Assert.AreEqual(test_value, result, "Compare Write/Read");
+        }
+
+        [TestMethod]
+        public void T27_ReadWriteBytesMany()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            var count = 2000;
+            var dataItems = new List<byte>();
+            for (int i = 0; i < count; i++)
+            {
+                dataItems.Add((byte)(i % 256));
+            }
+
+            plc.WriteBytes(DataType.DataBlock, 2, 0, dataItems.ToArray());
+
+            var res = plc.ReadBytes(DataType.DataBlock, 2, 0, count);
+
+            for (int x = 0; x < count; x++)
+            {
+                Assert.AreEqual(x % 256, res[x], $"Mismatch at offset {x}, expected {x % 256}, actual {res[x]}.");
+            }
+        }
+
+#if NET5_0_OR_GREATER
+
+        [TestMethod]
+        public void T27_ReadWriteBytesManyWithSpan()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            using var dataOwner = MemoryPool<byte>.Shared.Rent(2000);
+            var data = dataOwner.Memory.Span;
+            for (int i = 0; i < data.Length; i++)
+                data[i] = (byte)(i % 256);
+
+            plc.WriteBytes(DataType.DataBlock, 2, 0, data);
+
+            using var readDataOwner = MemoryPool<byte>.Shared.Rent(data.Length);
+            var readData = readDataOwner.Memory.Span.Slice(0, data.Length);
+            plc.ReadBytes(readData, DataType.DataBlock, 2, 0);
+
+            for (int x = 0; x < data.Length; x++)
+            {
+                Assert.AreEqual(x % 256, readData[x], $"Mismatch at offset {x}, expected {x % 256}, actual {readData[x]}.");
+            }
+        }
+
+#endif
+
+        [TestMethod]
+        public void T28_ReadClass_DoesntCrash_When_ReadingLessThan1Byte()
+        {
+            Assert.IsTrue(plc.IsConnected, "Before executing this test, the plc must be connected. Check constructor.");
+
+            var tc = new TestSmallClass
+            {
+                Bool1 = true
+            };
+
+            plc.WriteClass(tc, DB2);
+            var tc2 = plc.ReadClass<TestSmallClass>(DB2);
+
+            Assert.AreEqual(tc.Bool1, tc2.Bool1);
+        }
+
+        [TestMethod, ExpectedException(typeof(PlcException))]
+        public void T29_Read_Write_ThrowsWhenPlcIsNotReachable()
+        {
+            // leave plc Open
+            S7TestServer.Stop();
+
+            double test_value = 55.66;
+            plc.Write("DB1.DBD0", test_value);
+
+            var helper = plc.Read("DB1.DBD0");
+            Assert.AreEqual(helper, null, "Value in Read.");
+        }
+
+        [TestMethod]
+        public void T30_ReadWriteSingle()
+        {
+            float test_value = 55.6632f;
+            plc.Write("DB1.DBD0", test_value);
+            var helper = plc.Read("DB1.DBD0");
+            float test_value2 = Conversion.ConvertToFloat((uint)helper);
+
+            Assert.AreEqual(test_value, test_value2, "Compare Write/Read"); //No delta, datatype matches
+        }
+
+        [TestMethod]
+        public void T33_ReadWriteDateTimeLong()
+        {
+            var test_value = System.DateTime.Now;
+            var db = 1;
+            var offset = 0;
+
+            plc.WriteBytes(DataType.DataBlock, db, offset, Types.DateTimeLong.ToByteArray(test_value));
+            var test_value2 = plc.Read(DataType.DataBlock, db, offset, VarType.DateTimeLong, 1);
+            Assert.IsInstanceOfType(test_value2, typeof(System.DateTime));
+
+            Assert.AreEqual(test_value, test_value2, "Compare DateTimeLong Write/Read");
+        }
+
+#endregion
 
         #region Private methods
 
-        private static void ShutDownServiceS7oiehsx64()
+        #region IDisposable Support
+        private bool disposedValue = false; // To detect redundant calls
+
+        protected virtual void Dispose(bool disposing)
         {
-            try
+            if (!disposedValue)
             {
-                ServiceController sc = new ServiceController("s7oiehsx64");
-                switch (sc.Status)
+                if (disposing)
                 {
-                    case ServiceControllerStatus.Running:
-                        sc.Stop();
-                        break;
+                    plc.Close();
                 }
+
+                // TODO: free unmanaged resources (unmanaged objects) and override a finalizer below.
+                // TODO: set large fields to null.
+
+                disposedValue = true;
             }
-            catch { } // service not found
         }
 
+        // TODO: override a finalizer only if Dispose(bool disposing) above has code to free unmanaged resources.
+        // ~S7NetTests() {
+        //   // Do not change this code. Put cleanup code in Dispose(bool disposing) above.
+        //   Dispose(false);
+        // }
+
+        // This code added to correctly implement the disposable pattern.
+        public void Dispose()
+        {
+            // Do not change this code. Put cleanup code in Dispose(bool disposing) above.
+            Dispose(true);
+            // TODO: uncomment the following line if the finalizer is overridden above.
+            // GC.SuppressFinalize(this);
+        }
+        #endregion
         #endregion
     }
 }

S7.Net.UnitTest/Snap7/snap7.net.cs

@@ -36,11 +36,8 @@ namespace Snap7
 
     public class S7Consts
     {
-        #if __MonoCS__  // Assuming that we are using Unix release of Mono (otherwise modify it)
-        public const string Snap7LibName = "libsnap7.so";
-        #else
-        public const string Snap7LibName = "snap7.dll";
-        #endif
+        public const string Snap7LibName = "snap7";
+
         //------------------------------------------------------------------------------
         //                                  PARAMS LIST            
         //------------------------------------------------------------------------------

S7.Net.UnitTest/StreamTests.cs

@@ -0,0 +1,110 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net.UnitTest
+{
+    /// <summary>
+    /// Test stream which only gives 1 byte per read.
+    /// </summary>
+    class TestStream1BytePerRead : Stream
+    {
+        public TestStream1BytePerRead(byte[] data)
+        {
+            Data = data;
+        }
+
+        public override bool CanRead => _position < Data.Length;
+
+        public override bool CanSeek => throw new NotImplementedException();
+
+        public override bool CanWrite => throw new NotImplementedException();
+
+        public override long Length => throw new NotImplementedException();
+
+        public override long Position { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
+        public byte[] Data { get; }
+
+        int _position = 0;
+
+        public override void Flush()
+        {
+            throw new NotImplementedException();
+        }
+
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            if (_position >= Data.Length)
+            {
+                return Task.FromResult(0);
+            }
+
+            buffer[offset] = Data[_position];
+            ++_position;
+
+            return Task.FromResult(1);
+        }
+
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override void SetLength(long value)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    /// <summary>
+    /// These tests are intended to test <see cref="StreamExtensions"/> functions and other stream-related special cases.
+    /// </summary>
+    [TestClass]
+    public class StreamTests
+    {
+        public TestContext TestContext { get; set; }
+
+        [TestMethod]
+        public async Task TPKT_ReadRestrictedStreamAsync()
+        {
+            var fullMessage = ProtocolUnitTest.StringToByteArray("0300002902f0803203000000010002001400000401ff0400807710000100000103000000033f8ccccd");
+            var m = new TestStream1BytePerRead(fullMessage);
+            var t = await TPKT.ReadAsync(m, TestContext.CancellationTokenSource.Token);
+            Assert.AreEqual(fullMessage.Length, t.Length);
+            Assert.AreEqual(fullMessage.Last(), t.Data.Last());
+        }
+
+        [TestMethod]
+        public async Task TPKT_ReadRestrictedStream()
+        {
+            var fullMessage = ProtocolUnitTest.StringToByteArray("0300002902f0803203000000010002001400000401ff0400807710000100000103000000033f8ccccd");
+            var m = new TestStream1BytePerRead(fullMessage);
+            var t = await TPKT.ReadAsync(m, CancellationToken.None);
+            Assert.AreEqual(fullMessage.Length, t.Length);
+            Assert.AreEqual(fullMessage.Last(), t.Data.Last());
+        }
+
+        [TestMethod]
+        public async Task TPKT_ReadStreamTooShort()
+        {
+            var fullMessage = ProtocolUnitTest.StringToByteArray("0300002902f0803203000000010002001400");
+            var m = new TestStream1BytePerRead(fullMessage);
+            await Assert.ThrowsExceptionAsync<TPKTInvalidException>(() => TPKT.ReadAsync(m, CancellationToken.None));
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/BooleanTests.cs

@@ -0,0 +1,38 @@
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Boolean = S7.Net.Types.Boolean;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class BooleanTests
+    {
+        [DataTestMethod]
+        [DataRow(0)]
+        [DataRow(1)]
+        [DataRow(2)]
+        [DataRow(3)]
+        [DataRow(4)]
+        [DataRow(5)]
+        [DataRow(6)]
+        [DataRow(7)]
+        public void TestValidSetBitValues(int index)
+        {
+            Assert.AreEqual(Math.Pow(2, index), Boolean.SetBit(0, index));
+        }
+
+        [DataTestMethod]
+        [DataRow(0)]
+        [DataRow(1)]
+        [DataRow(2)]
+        [DataRow(3)]
+        [DataRow(4)]
+        [DataRow(5)]
+        [DataRow(6)]
+        [DataRow(7)]
+        public void TestValidClearBitValues(int index)
+        {
+            Assert.AreEqual((byte) ((uint) Math.Pow(2, index) ^ uint.MaxValue), Boolean.ClearBit(byte.MaxValue, index));
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/ClassTests.cs

@@ -0,0 +1,51 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class ClassTests
+    {
+        [TestMethod]
+        public void GetClassSizeTest()
+        {
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(1, 1)), 6);
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(2, 15)), 6);
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(2, 16)), 6);
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(2, 17)), 8);
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(3, 15)), 8);
+            Assert.AreEqual(Class.GetClassSize(new TestClassUnevenSize(3, 17)), 10);
+        }
+
+        /// <summary>
+        /// Ensure Uint32 is correctly parsed through ReadClass functions. Adresses issue https://github.com/S7NetPlus/s7netplus/issues/414
+        /// </summary>
+        [TestMethod]
+        public void TestUint32Read()
+        {
+            var result = new TestUint32();
+            var data = new byte[4] { 0, 0, 0, 5 };
+            var bytesRead = Class.FromBytes(result, data);
+            Assert.AreEqual(bytesRead, data.Length);
+            Assert.AreEqual(5u, result.Value1);
+        }
+
+        private class TestClassUnevenSize
+        {
+            public bool Bool { get; set; }
+            public byte[] Bytes { get; set; }
+            public bool[] Bools { get; set; }
+
+            public TestClassUnevenSize(int byteCount, int bitCount)
+            {
+                Bytes = new byte[byteCount];
+                Bools = new bool[bitCount];
+            }
+        }
+
+        private class TestUint32
+        {
+            public uint Value1 { get; set; }
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/DateTimeLongTests.cs

@@ -0,0 +1,171 @@
+using System;
+using System.Linq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    public static class DateTimeLongTests
+    {
+        private static readonly DateTime SampleDateTime = new DateTime(1993, 12, 25, 8, 12, 34, 567);
+
+        private static readonly byte[] SampleByteArray = {0x07, 0xC9, 0x0C, 0x19, 0x07, 0x08, 0x0C, 0x22, 0x21, 0xCB, 0xBB, 0xC0 };
+
+        private static readonly byte[] SpecMinByteArray =
+        {
+            0x07, 0xB2, 0x01, 0x01,  (byte) (int) (Types.DateTimeLong.SpecMinimumDateTime.DayOfWeek + 1), 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        };
+
+        private static readonly byte[] SpecMaxByteArray =
+        {
+            0x08, 0xD6, 0x04, 0x0B,  (byte) (int) (Types.DateTimeLong.SpecMaximumDateTime.DayOfWeek + 1), 0x17, 0x2F, 0x10, 0x32, 0xE7, 0x01, 0x80
+        };
+
+        [TestClass]
+        public class FromByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertFromByteArrayEquals(SampleDateTime, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertFromByteArrayEquals(Types.DateTimeLong.SpecMinimumDateTime, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertFromByteArrayEquals(Types.DateTimeLong.SpecMaximumDateTime, SpecMaxByteArray);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnLessThan12Bytes()
+            {
+                Types.DateTimeLong.FromByteArray(new byte[11]);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnMoreTHan12Bytes()
+            {
+                Types.DateTimeLong.FromByteArray(new byte[13]);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidYear()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(0, 0xa0));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroMonth()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(2, 0x00));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeMonth()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(2, 0x13));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroDay()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(3, 0x00));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeDay()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(3, 0x32));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidHour()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(5, 0x24));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidMinute()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(6, 0x60));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidSecond()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(7, 0x60));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidNanosecondsFirstDigit()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(8, 0x3B));
+            }
+
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroDayOfWeek()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(4, 0));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeDayOfWeek()
+            {
+                Types.DateTimeLong.FromByteArray(MutateSample(4, 8));
+            }
+
+            private static void AssertFromByteArrayEquals(DateTime expected, params byte[] bytes)
+            {
+                Assert.AreEqual(expected, Types.DateTimeLong.FromByteArray(bytes));
+            }
+
+            private static byte[] MutateSample(int index, byte value) =>
+                SampleByteArray.Select((b, i) => i == index ? value : b).ToArray();
+        }
+
+        [TestClass]
+        public class ToByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertToByteArrayEquals(SampleDateTime, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertToByteArrayEquals(Types.DateTimeLong.SpecMinimumDateTime, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertToByteArrayEquals(Types.DateTimeLong.SpecMaximumDateTime, SpecMaxByteArray);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeBeforeSpecMinimum()
+            {
+                Types.DateTimeLong.ToByteArray(new DateTime(1950, 1, 1));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeAfterSpecMaximum()
+            {
+                Types.DateTimeLong.ToByteArray(new DateTime(2790, 1, 1));
+            }
+
+            private static void AssertToByteArrayEquals(DateTime value, params byte[] expected)
+            {
+                CollectionAssert.AreEqual(expected, Types.DateTimeLong.ToByteArray(value));
+            }
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/DateTimeTests.cs

@@ -0,0 +1,176 @@
+using System;
+using System.Linq;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    public static class DateTimeTests
+    {
+        private static readonly DateTime SampleDateTime = new DateTime(1993, 12, 25, 8, 12, 34, 567);
+
+        private static readonly byte[] SampleByteArray = {0x93, 0x12, 0x25, 0x08, 0x12, 0x34, 0x56, 7 << 4 | 7};
+
+        private static readonly byte[] SpecMinByteArray =
+        {
+            0x90, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, (byte) (int) (Types.DateTime.SpecMinimumDateTime.DayOfWeek + 1)
+        };
+
+        private static readonly byte[] SpecMaxByteArray =
+        {
+            0x89, 0x12, 0x31, 0x23, 0x59, 0x59, 0x99, (byte) (9 << 4 | (int) (Types.DateTime.SpecMaximumDateTime.DayOfWeek + 1))
+        };
+
+        [TestClass]
+        public class FromByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertFromByteArrayEquals(SampleDateTime, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertFromByteArrayEquals(Types.DateTime.SpecMinimumDateTime, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertFromByteArrayEquals(Types.DateTime.SpecMaximumDateTime, SpecMaxByteArray);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnLessThan8Bytes()
+            {
+                Types.DateTime.FromByteArray(new byte[7]);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnMoreTHan8Bytes()
+            {
+                Types.DateTime.FromByteArray(new byte[9]);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidYear()
+            {
+                Types.DateTime.FromByteArray(MutateSample(0, 0xa0));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroMonth()
+            {
+                Types.DateTime.FromByteArray(MutateSample(1, 0x00));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeMonth()
+            {
+                Types.DateTime.FromByteArray(MutateSample(1, 0x13));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroDay()
+            {
+                Types.DateTime.FromByteArray(MutateSample(2, 0x00));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeDay()
+            {
+                Types.DateTime.FromByteArray(MutateSample(2, 0x32));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidHour()
+            {
+                Types.DateTime.FromByteArray(MutateSample(3, 0x24));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidMinute()
+            {
+                Types.DateTime.FromByteArray(MutateSample(4, 0x60));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidSecond()
+            {
+                Types.DateTime.FromByteArray(MutateSample(5, 0x60));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidFirstTwoMillisecondDigits()
+            {
+                Types.DateTime.FromByteArray(MutateSample(6, 0xa0));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnInvalidThirdMillisecondDigit()
+            {
+                Types.DateTime.FromByteArray(MutateSample(7, 10 << 4));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnZeroDayOfWeek()
+            {
+                Types.DateTime.FromByteArray(MutateSample(7, 0));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTooLargeDayOfWeek()
+            {
+                Types.DateTime.FromByteArray(MutateSample(7, 8));
+            }
+
+            private static void AssertFromByteArrayEquals(DateTime expected, params byte[] bytes)
+            {
+                Assert.AreEqual(expected, Types.DateTime.FromByteArray(bytes));
+            }
+
+            private static byte[] MutateSample(int index, byte value) =>
+                SampleByteArray.Select((b, i) => i == index ? value : b).ToArray();
+        }
+
+        [TestClass]
+        public class ToByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertToByteArrayEquals(SampleDateTime, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertToByteArrayEquals(Types.DateTime.SpecMinimumDateTime, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertToByteArrayEquals(Types.DateTime.SpecMaximumDateTime, SpecMaxByteArray);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeBeforeSpecMinimum()
+            {
+                Types.DateTime.ToByteArray(new DateTime(1970, 1, 1));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeAfterSpecMaximum()
+            {
+                Types.DateTime.ToByteArray(new DateTime(2090, 1, 1));
+            }
+
+            private static void AssertToByteArrayEquals(DateTime value, params byte[] expected)
+            {
+                CollectionAssert.AreEqual(expected, Types.DateTime.ToByteArray(value));
+            }
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/S7StringTests.cs

@@ -0,0 +1,152 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+using System;
+using System.Collections;
+using System.Linq;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class S7StringTests
+    {
+        [TestMethod]
+        public void ReadEmptyStringWithZeroByteLength()
+        {
+            AssertFromByteArrayEquals("", 0, 0);
+        }
+
+        [TestMethod]
+        public void ReadEmptyStringWithOneByteLength()
+        {
+            AssertFromByteArrayEquals("", 1, 0, 0);
+        }
+
+        [TestMethod]
+        public void ReadEmptyStringWithOneByteGarbage()
+        {
+            AssertFromByteArrayEquals("", 1, 0, (byte) 'a');
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringTooShort()
+        {
+            Assert.ThrowsException<PlcException>(() => AssertFromByteArrayEquals("", 1));
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringSizeLargerThanCapacity()
+        {
+            Assert.ThrowsException<PlcException>(() => S7String.FromByteArray(new byte[] { 3, 5, 0, 1, 2 }));
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringCapacityTooLarge()
+        {
+            Assert.ThrowsException<ArgumentException>(() => AssertToByteArrayAndBackEquals("", 300, 0));
+        }
+
+        [TestMethod]
+        public void ReadA()
+        {
+            AssertFromByteArrayEquals("A", 1, 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void ReadAbc()
+        {
+            AssertFromByteArrayEquals("Abc", 3, 3, (byte) 'A', (byte) 'b', (byte) 'c');
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthZero()
+        {
+            Assert.ThrowsException<ArgumentNullException>(() => AssertToByteArrayAndBackEquals(null, 0, 0, 0));
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthZero()
+        {
+            AssertToByteArrayAndBackEquals("", 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthZero()
+        {
+            AssertToByteArrayAndBackEquals("", 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthOne()
+        {
+            Assert.ThrowsException<ArgumentNullException>(() => AssertToByteArrayAndBackEquals(null, 1, 1, 0));
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthOne()
+        {
+            AssertToByteArrayAndBackEquals("", 1, 1, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthOne()
+        {
+            AssertToByteArrayAndBackEquals("A", 1, 1, 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthTwo()
+        {
+            AssertToByteArrayAndBackEquals("A", 2, 2, 1, (byte) 'A', 0);
+        }
+
+        [TestMethod]
+        public void WriteAbcWithStringLargerThanReservedLength()
+        {
+            Assert.ThrowsException<ArgumentException>(() => S7String.ToByteArray("Abc", 2));
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthThree()
+        {
+            AssertToByteArrayAndBackEquals("Abc", 3, 3, 3, (byte) 'A', (byte) 'b', (byte) 'c');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthFour()
+        {
+            AssertToByteArrayAndBackEquals("Abc", 4, 4, 3, (byte) 'A', (byte) 'b', (byte) 'c', 0);
+        }
+
+        [TestMethod]
+        public void OddS7StringByteLength()
+        {
+            AssertVarTypeToByteLength(VarType.S7String, 1, 4);
+        }
+
+        [TestMethod]
+        public void EvenS7StringByteLength()
+        {
+            AssertVarTypeToByteLength(VarType.S7String, 2, 4);
+        }
+
+        private static void AssertFromByteArrayEquals(string expected, params byte[] bytes)
+        {
+            var convertedString = S7String.FromByteArray(bytes);
+            Assert.AreEqual(expected, convertedString);
+        }
+
+        private static void AssertToByteArrayAndBackEquals(string value, int reservedLength, params byte[] expected)
+        {
+            var convertedData = S7String.ToByteArray(value, reservedLength);
+            CollectionAssert.AreEqual(expected, convertedData);
+            var convertedBack = S7String.FromByteArray(convertedData);
+            Assert.AreEqual(value, convertedBack);
+        }
+
+        private void AssertVarTypeToByteLength(VarType varType, int count, int expectedByteLength)
+        {
+            var byteLength = Plc.VarTypeToByteLength(varType, count);
+            Assert.AreEqual(expectedByteLength, byteLength);
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/S7WStringTests.cs

@@ -0,0 +1,151 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+using System;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class S7WStringTests
+    {
+        [TestMethod]
+        public void ReadEmptyStringWithZeroLength()
+        {
+            AssertFromByteArrayEquals("", 0, 0 , 0, 0);
+        }
+
+        [TestMethod]
+        public void ReadEmptyStringWithOneCharLength()
+        {
+            AssertFromByteArrayEquals("", 0, 1, 0, 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void ReadEmptyStringWithOneCharGarbage()
+        {
+
+            AssertFromByteArrayEquals("", 0, 1, 0, 0, 0x00, 0x41);
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringTooShort()
+        {
+            Assert.ThrowsException<PlcException>(() => AssertFromByteArrayEquals("", 0, 1));
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringSizeLargerThanCapacity()
+        {
+            Assert.ThrowsException<PlcException>(() => S7WString.FromByteArray(new byte[] { 0, 3, 0, 5, 0, 0x00, 0x41, 0x00, 0x41, 0x00, 0x41}));
+        }
+
+        [TestMethod]
+        public void ReadMalformedStringCapacityTooLarge()
+        {
+            Assert.ThrowsException<ArgumentException>(() => AssertToByteArrayAndBackEquals("", 20000, 0));
+        }
+
+        [TestMethod]
+        public void ReadA()
+        {
+            AssertFromByteArrayEquals("A", 0, 1, 0, 1, 0x00, 0x41);
+        }
+
+        [TestMethod]
+        public void ReadAbc()
+        {
+            AssertFromByteArrayEquals("Abc", 0, 3, 0, 3, 0x00, 0x41, 0x00, 0x62, 0x00, 0x63);
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthZero()
+        {
+            Assert.ThrowsException<ArgumentNullException>(() => AssertToByteArrayAndBackEquals(null, 0, 0, 0, 0, 0));
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthZero()
+        {
+            AssertToByteArrayAndBackEquals("", 0, 0, 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthZero()
+        {
+            AssertToByteArrayAndBackEquals("", 0, 0, 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthOne()
+        {
+            Assert.ThrowsException<ArgumentNullException>(() => AssertToByteArrayAndBackEquals(null, 1, 0, 1 , 0, 0));
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthOne()
+        {
+            AssertToByteArrayAndBackEquals("", 1, 0, 1, 0, 0, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthOne()
+        {
+            AssertToByteArrayAndBackEquals("A", 1, 0, 1, 0, 1, 0x00, 0x41);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthTwo()
+        {
+            AssertToByteArrayAndBackEquals("A", 2, 0, 2, 0, 1, 0x00, 0x41, 0, 0);
+        }
+
+        [TestMethod]
+        public void WriteAbcWithStringLargerThanReservedLength()
+        {
+            Assert.ThrowsException<ArgumentException>(() => S7WString.ToByteArray("Abc", 2));
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthThree()
+        {
+            AssertToByteArrayAndBackEquals("Abc", 3, 0, 3, 0, 3, 0x00, 0x41, 0x00, 0x62, 0x00, 0x63);
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthFour()
+        {
+            AssertToByteArrayAndBackEquals("Abc", 4, 0, 4, 0, 3, 0x00, 0x41, 0x00, 0x62, 0x00, 0x63, 0 , 0);
+        }
+
+        private static void AssertFromByteArrayEquals(string expected, params byte[] bytes)
+        {
+            var convertedString = S7WString.FromByteArray(bytes);
+            Assert.AreEqual(expected, convertedString);
+        }
+
+        [TestMethod]
+        public void OddS7WStringByteLength()
+        {
+            AssertVarTypeToByteLength(VarType.S7WString, 1, 6);
+        }
+
+        [TestMethod]
+        public void EvenS7WStringByteLength()
+        {
+            AssertVarTypeToByteLength(VarType.S7WString, 2, 8);
+        }
+
+        private static void AssertToByteArrayAndBackEquals(string value, int reservedLength, params byte[] expected)
+        {
+            var convertedData = S7WString.ToByteArray(value, reservedLength);
+            CollectionAssert.AreEqual(expected, convertedData);
+            var convertedBack = S7WString.FromByteArray(convertedData);
+            Assert.AreEqual(value, convertedBack);
+        }
+
+        private void AssertVarTypeToByteLength(VarType varType, int count, int expectedByteLength)
+        {
+            var byteLength = Plc.VarTypeToByteLength(varType, count);
+            Assert.AreEqual(expectedByteLength, byteLength);
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/StringTests.cs

@@ -0,0 +1,85 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using S7.Net.Types;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    [TestClass]
+    public class StringTests
+    {
+        [TestMethod]
+        public void WriteNullWIthReservedLengthZero()
+        {
+            AssertToByteArrayEquals(null, 0);
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthZero()
+        {
+            AssertToByteArrayEquals("", 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthZero()
+        {
+            AssertToByteArrayEquals("A", 0);
+        }
+
+        [TestMethod]
+        public void WriteNullWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals(null, 1, 0);
+        }
+
+        [TestMethod]
+        public void WriteEmptyStringWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("", 1, 0);
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("A", 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void WriteAWithReservedLengthTwo()
+        {
+            AssertToByteArrayEquals("A", 2, (byte) 'A', 0);
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthOne()
+        {
+            AssertToByteArrayEquals("Abc", 1, (byte) 'A');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthTwo()
+        {
+            AssertToByteArrayEquals("Abc", 2, (byte) 'A', (byte) 'b');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthThree()
+        {
+            AssertToByteArrayEquals("Abc", 3, (byte) 'A', (byte) 'b', (byte) 'c');
+        }
+
+        [TestMethod]
+        public void WriteAbcWithReservedLengthFour()
+        {
+            AssertToByteArrayEquals("Abc", 4, (byte) 'A', (byte) 'b', (byte) 'c', 0);
+        }
+
+        private static void AssertFromByteArrayEquals(string expected, params byte[] bytes)
+        {
+            Assert.AreEqual(expected, String.FromByteArray(bytes));
+        }
+
+        private static void AssertToByteArrayEquals(string value, int reservedLength, params byte[] expected)
+        {
+            CollectionAssert.AreEqual(expected, String.ToByteArray(value, reservedLength));
+        }
+    }
+}

S7.Net.UnitTest/TypeTests/TimeSpanTests.cs

@@ -0,0 +1,82 @@
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace S7.Net.UnitTest.TypeTests
+{
+    public static class TimeSpanTests
+    {
+        private static readonly TimeSpan SampleTimeSpan = new TimeSpan(12, 0, 59, 37, 856);
+
+        private static readonly byte[] SampleByteArray = { 0x3E, 0x02, 0xE8, 0x00 };
+
+        private static readonly byte[] SpecMinByteArray = { 0x80, 0x00, 0x00, 0x00 };
+        
+        private static readonly byte[] SpecMaxByteArray = { 0x7F, 0xFF, 0xFF, 0xFF };
+
+        [TestClass]
+        public class FromByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertFromByteArrayEquals(SampleTimeSpan, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertFromByteArrayEquals(Types.TimeSpan.SpecMinimumTimeSpan, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertFromByteArrayEquals(Types.TimeSpan.SpecMaximumTimeSpan, SpecMaxByteArray);
+            }
+
+            private static void AssertFromByteArrayEquals(TimeSpan expected, params byte[] bytes)
+            {
+                Assert.AreEqual(expected, Types.TimeSpan.FromByteArray(bytes));
+            }
+        }
+
+        [TestClass]
+        public class ToByteArray
+        {
+            [TestMethod]
+            public void Sample()
+            {
+                AssertToByteArrayEquals(SampleTimeSpan, SampleByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMinimum()
+            {
+                AssertToByteArrayEquals(Types.TimeSpan.SpecMinimumTimeSpan, SpecMinByteArray);
+            }
+
+            [TestMethod]
+            public void SpecMaximum()
+            {
+                AssertToByteArrayEquals(Types.TimeSpan.SpecMaximumTimeSpan, SpecMaxByteArray);
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeBeforeSpecMinimum()
+            {
+                Types.TimeSpan.ToByteArray(TimeSpan.FromDays(-25));
+            }
+
+            [TestMethod, ExpectedException(typeof(ArgumentOutOfRangeException))]
+            public void ThrowsOnTimeAfterSpecMaximum()
+            {
+                Types.TimeSpan.ToByteArray(new TimeSpan(30, 15, 15, 15, 15));
+            }
+
+            private static void AssertToByteArrayEquals(TimeSpan value, params byte[] expected)
+            {
+                CollectionAssert.AreEqual(expected, Types.TimeSpan.ToByteArray(value));
+            }
+        }
+    }
+}

S7.Net/COTP.cs

@@ -0,0 +1,120 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net
+{
+
+    /// <summary>
+    /// COTP Protocol functions and types
+    /// </summary>
+    internal class COTP
+    {
+        public enum PduType : byte
+        {
+            Data = 0xf0,
+            ConnectionConfirmed = 0xd0
+        }
+        /// <summary>
+        /// Describes a COTP TPDU (Transport protocol data unit)
+        /// </summary>
+        public class TPDU
+        {
+            public TPKT TPkt { get; }
+            public byte HeaderLength;
+            public PduType PDUType;
+            public int TPDUNumber;
+            public byte[] Data;
+            public bool LastDataUnit;
+
+            public TPDU(TPKT tPKT)
+            {
+                TPkt = tPKT;
+
+                HeaderLength = tPKT.Data[0]; // Header length excluding this length byte
+                if (HeaderLength >= 2)
+                {
+                    PDUType = (PduType)tPKT.Data[1];
+                    if (PDUType == PduType.Data) //DT Data
+                    {
+                        var flags = tPKT.Data[2];
+                        TPDUNumber = flags & 0x7F;
+                        LastDataUnit = (flags & 0x80) > 0;
+                        Data = new byte[tPKT.Data.Length - HeaderLength - 1]; // substract header length byte + header length.
+                        Array.Copy(tPKT.Data, HeaderLength + 1, Data, 0, Data.Length);
+                        return;
+                    }
+                    //TODO: Handle other PDUTypes
+                }
+                Data = new byte[0];
+            }
+
+            /// <summary>
+            /// Reads COTP TPDU (Transport protocol data unit) from the network stream
+            /// See: https://tools.ietf.org/html/rfc905
+            /// </summary>
+            /// <param name="stream">The socket to read from</param>
+            /// <param name="cancellationToken">A cancellation token that can be used to cancel the asynchronous operation.</param>
+            /// <returns>COTP DPDU instance</returns>
+            public static async Task<TPDU> ReadAsync(Stream stream, CancellationToken cancellationToken)
+            {
+                var tpkt = await TPKT.ReadAsync(stream, cancellationToken).ConfigureAwait(false);
+                if (tpkt.Length == 0)
+                {
+                    throw new TPDUInvalidException("No protocol data received");
+                }
+                return new TPDU(tpkt);
+            }
+
+            public override string ToString()
+            {
+                return string.Format("Length: {0} PDUType: {1} TPDUNumber: {2} Last: {3} Segment Data: {4}",
+                    HeaderLength,
+                    PDUType,
+                    TPDUNumber,
+                    LastDataUnit,
+                    BitConverter.ToString(Data)
+                    );
+            }
+
+        }
+
+        /// <summary>
+        /// Describes a COTP TSDU (Transport service data unit). One TSDU consist of 1 ore more TPDUs
+        /// </summary>
+        public class TSDU
+        {
+            /// <summary>
+            /// Reads the full COTP TSDU (Transport service data unit)
+            /// See: https://tools.ietf.org/html/rfc905
+            /// </summary>
+            /// <param name="stream">The stream to read from</param>
+            /// <param name="cancellationToken">A cancellation token that can be used to cancel the asynchronous operation.</param>
+            /// <returns>Data in TSDU</returns>
+            public static async Task<byte[]> ReadAsync(Stream stream, CancellationToken cancellationToken)
+            {
+                var segment = await TPDU.ReadAsync(stream, cancellationToken).ConfigureAwait(false);
+
+                if (segment.LastDataUnit)
+                {
+                    return segment.Data;
+                }
+
+                // More segments are expected, prepare a buffer to store all data
+                var buffer = new byte[segment.Data.Length];
+                Array.Copy(segment.Data, buffer, segment.Data.Length);
+
+                while (!segment.LastDataUnit)
+                {
+                    segment = await TPDU.ReadAsync(stream, cancellationToken).ConfigureAwait(false);
+                    var previousLength = buffer.Length;
+                    Array.Resize(ref buffer, buffer.Length + segment.Data.Length);
+                    Array.Copy(segment.Data, 0, buffer, previousLength, segment.Data.Length);
+                }
+
+                return buffer;
+            }
+        }
+    }
+}

S7.Net/Compat/TcpClientMixins.cs

@@ -0,0 +1,19 @@
+using System.Net.Sockets;
+
+namespace S7.Net
+{
+    public static class TcpClientMixins
+    {
+        #if NETSTANDARD1_3
+        public static void Close(this TcpClient tcpClient)
+        {
+            tcpClient.Dispose();
+        }
+
+        public static void Connect(this TcpClient tcpClient, string host, int port)
+        {
+            tcpClient.ConnectAsync(host, port).GetAwaiter().GetResult();
+        }
+        #endif
+    }
+}

S7.Net/Conversion.cs

@@ -15,15 +15,11 @@ namespace S7.Net
         /// <returns></returns>
         public static int BinStringToInt32(this string txt)
         {
-            int cnt = 0;
             int ret = 0;
 
-            for (cnt = txt.Length - 1; cnt >= 0; cnt += -1)
+            for (int i = 0; i < txt.Length; i++)
             {
-                if (int.Parse(txt.Substring(cnt, 1)) == 1)
-                {
-                    ret += (int)(Math.Pow(2, (txt.Length - 1 - cnt)));
-                }
+                ret = (ret << 1) | ((txt[i] == '1') ? 1 : 0);
             }
             return ret;
         }
@@ -35,20 +31,7 @@ namespace S7.Net
         /// <returns></returns>
         public static byte? BinStringToByte(this string txt)
         {
-            int cnt = 0;
-            int ret = 0;
-
-            if (txt.Length == 8)
-            {
-                for (cnt = 7; cnt >= 0; cnt += -1)
-                {
-                    if (int.Parse(txt.Substring(cnt, 1)) == 1)
-                    {
-                        ret += (int)(Math.Pow(2, (txt.Length - 1 - cnt)));
-                    }
-                }
-                return (byte)ret;
-            }
+            if (txt.Length == 8) return (byte)BinStringToInt32(txt);
             return null;
         }
 
@@ -147,7 +130,7 @@ namespace S7.Net
                 }
                 return txt;
             }
-            catch 
+            catch
             {
                 return "";
             }
@@ -155,19 +138,59 @@ namespace S7.Net
 
         /// <summary>
         /// Helper to get a bit value given a byte and the bit index.
-        /// Example: DB1.DBX0.5 -> var bytes = ReadBytes(DB1.DBW0); bool bit = bytes[0].SelectBit(5); 
+        /// <br/>
+        /// <example>
+        ///   Get the bit at DB1.DBX0.5:
+        ///   <code>
+        ///     byte data = ReadByte("DB1.DBB0");
+        ///     bool bit = data.SelectBit(5);
+        ///   </code>
+        /// </example>
         /// </summary>
-        /// <param name="data"></param>
-        /// <param name="bitPosition"></param>
-        /// <returns></returns>
-        public static bool SelectBit(this byte data, int bitPosition)
+        /// <param name="data">The data to get from.</param>
+        /// <param name="index">The zero-based index of the bit to get.</param>
+        /// <returns>The Boolean value will get.</returns>
+        public static bool SelectBit(this byte data, int index)
         {
-            int mask = 1 << bitPosition;
+            int mask = 1 << index;
             int result = data & mask;
 
             return (result != 0);
         }
 
+        /// <summary>
+        /// Helper to set a bit value to the given byte at the bit index.
+        /// <br/>
+        /// <example>
+        ///   Set the bit at index 4:
+        ///   <code>
+        ///     byte data = 0;
+        ///     data.SetBit(4, true);
+        ///   </code>
+        /// </example>
+        /// </summary>
+        /// <param name="data">The data to be modified.</param>
+        /// <param name="index">The zero-based index of the bit to set.</param>
+        /// <param name="value">The Boolean value to assign to the bit.</param>
+        public static void SetBit(this ref byte data, int index, bool value)
+        {
+            if ((uint)index > 7)
+            {
+                return;
+            }
+
+            if (value)
+            {
+                byte mask = (byte)(1 << index);
+                data |= mask;
+            }
+            else
+            {
+                byte mask = (byte)~(1 << index);
+                data &= mask;
+            }
+        }
+
         /// <summary>
         /// Converts from ushort value to short value; it's used to retrieve negative values from words
         /// </summary>
@@ -217,26 +240,26 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Converts from double to DWord (DBD)
+        /// Converts from float to DWord (DBD)
         /// </summary>
         /// <param name="input"></param>
         /// <returns></returns>
-        public static UInt32 ConvertToUInt(this double input) 
+        public static UInt32 ConvertToUInt(this float input)
         {
             uint output;
-            output = S7.Net.Types.DWord.FromByteArray(S7.Net.Types.Double.ToByteArray(input));
+            output = S7.Net.Types.DWord.FromByteArray(S7.Net.Types.Real.ToByteArray(input));
             return output;
         }
 
         /// <summary>
-        /// Converts from DWord (DBD) to double
+        /// Converts from DWord (DBD) to float
         /// </summary>
         /// <param name="input"></param>
         /// <returns></returns>
-        public static double ConvertToDouble(this uint input)
+        public static float ConvertToFloat(this uint input)
         {
-            double output;
-            output = S7.Net.Types.Double.FromByteArray(S7.Net.Types.DWord.ToByteArray(input));
+            float output;
+            output = S7.Net.Types.Real.FromByteArray(S7.Net.Types.DWord.ToByteArray(input));
             return output;
         }
     }

S7.Net/Enums.cs

@@ -10,6 +10,16 @@
         /// </summary>
         S7200 = 0,
 
+        /// <summary>
+        /// Siemens Logo 0BA8
+        /// </summary>
+        Logo0BA8 = 1,
+
+        /// <summary>
+        /// S7 200 Smart
+        /// </summary>
+        S7200Smart = 2,
+
         /// <summary>
         /// S7 300 cpu type
         /// </summary>
@@ -159,10 +169,25 @@
         Real,
 
         /// <summary>
-        /// String variable type (variable)
+        /// LReal variable type (64 bits, 8 bytes)
+        /// </summary>
+        LReal,
+
+        /// <summary>
+        /// Char Array / C-String variable type (variable)
         /// </summary>
         String,
 
+        /// <summary>
+        /// S7 String variable type (variable)
+        /// </summary>
+        S7String,
+
+        /// <summary>
+        /// S7 WString variable type (variable)
+        /// </summary>
+        S7WString,
+
         /// <summary>
         /// Timer variable type
         /// </summary>
@@ -171,6 +196,26 @@
         /// <summary>
         /// Counter variable type
         /// </summary>
-        Counter
+        Counter,
+
+        /// <summary>
+        /// DateTIme variable type
+        /// </summary>
+        DateTime,
+        
+        /// <summary>
+        /// IEC date (legacy) variable type
+        /// </summary>
+        Date,
+
+        /// <summary>
+        /// DateTimeLong variable type
+        /// </summary>
+        DateTimeLong,
+        
+        /// <summary>
+        /// S7 TIME variable type - serialized as S7 DInt and deserialized as C# TimeSpan 
+        /// </summary>
+        Time
     }
 }

S7.Net/Helper/DateTimeExtensions.cs

@@ -0,0 +1,23 @@
+using System;
+using S7.Net.Types;
+using DateTime = System.DateTime;
+
+namespace S7.Net.Helper
+{
+    public static class DateTimeExtensions
+    {
+        public static ushort GetDaysSinceIecDateStart(this DateTime dateTime)
+        {
+            if (dateTime < Date.IecMinDate)
+            {
+                throw new ArgumentOutOfRangeException($"DateTime must be at least {Date.IecMinDate:d}");
+            }
+            if (dateTime > Date.IecMaxDate)
+            {
+                throw new ArgumentOutOfRangeException($"DateTime must be lower than {Date.IecMaxDate:d}");
+            }
+
+            return (ushort)(dateTime - Date.IecMinDate).TotalDays;
+        }
+    }
+}

S7.Net/Helper/MemoryStreamExtension.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Buffers;
+using System.IO;
+
+namespace S7.Net.Helper
+{
+#if !NET5_0_OR_GREATER
+    internal static class MemoryStreamExtension
+    {
+        /// <summary>
+        /// Helper function to write to whole content of the given byte array to a memory stream.
+        /// 
+        /// Writes all bytes in value from 0 to value.Length to the memory stream.
+        /// </summary>
+        /// <param name="stream"></param>
+        /// <param name="value"></param>
+        public static void Write(this MemoryStream stream, byte[] value)
+        {
+            stream.Write(value, 0, value.Length);
+        }
+
+        /// <summary>
+        /// Helper function to write the whole content of the given byte span to a memory stream.
+        /// </summary>
+        /// <param name="stream"></param>
+        /// <param name="value"></param>
+        public static void Write(this MemoryStream stream, ReadOnlySpan<byte> value)
+        {
+            byte[] buffer = ArrayPool<byte>.Shared.Rent(value.Length);
+
+            value.CopyTo(buffer);
+            stream.Write(buffer, 0, value.Length);
+
+            ArrayPool<byte>.Shared.Return(buffer);
+        }
+    }
+#endif
+}

S7.Net/Internal/TaskQueue.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net.Internal
+{
+    internal class TaskQueue
+    {
+        private static readonly object Sentinel = new object();
+
+        private Task prev = Task.FromResult(Sentinel);
+
+        public async Task<T> Enqueue<T>(Func<Task<T>> action)
+        {
+            var tcs = new TaskCompletionSource<object>();
+            await Interlocked.Exchange(ref prev, tcs.Task).ConfigureAwait(false);
+
+            try
+            {
+                return await action.Invoke().ConfigureAwait(false);
+            }
+            finally
+            {
+                tcs.SetResult(Sentinel);
+            }
+        }
+    }
+}

S7.Net/InvalidDataException.cs

@@ -0,0 +1,43 @@
+using System;
+
+namespace S7.Net
+{
+    #if NET_FULL
+    [Serializable]
+    #endif
+    public class InvalidDataException : Exception
+    {
+        public byte[] ReceivedData { get; }
+        public int ErrorIndex { get; }
+        public byte ExpectedValue { get; }
+
+        public InvalidDataException(string message, byte[] receivedData, int errorIndex, byte expectedValue)
+            : base(FormatMessage(message, receivedData, errorIndex, expectedValue))
+        {
+            ReceivedData = receivedData;
+            ErrorIndex = errorIndex;
+            ExpectedValue = expectedValue;
+        }
+
+        #if NET_FULL
+        protected InvalidDataException(System.Runtime.Serialization.SerializationInfo info,
+            System.Runtime.Serialization.StreamingContext context) : base(info, context)
+        {
+            ReceivedData = (byte[]) info.GetValue(nameof(ReceivedData), typeof(byte[]));
+            ErrorIndex = info.GetInt32(nameof(ErrorIndex));
+            ExpectedValue = info.GetByte(nameof(ExpectedValue));
+        }
+        #endif
+
+        private static string FormatMessage(string message, byte[] receivedData, int errorIndex, byte expectedValue)
+        {
+            if (errorIndex >= receivedData.Length)
+                throw new ArgumentOutOfRangeException(nameof(errorIndex),
+                    $"{nameof(errorIndex)} {errorIndex} is outside the bounds of {nameof(receivedData)} with length {receivedData.Length}.");
+
+            return $"{message} Invalid data received. Expected '{expectedValue}' at index {errorIndex}, " +
+                $"but received {receivedData[errorIndex]}. See the {nameof(ReceivedData)} property " +
+                "for the full message received.";
+        }
+    }
+}

S7.Net/PLCAddress.cs

@@ -0,0 +1,207 @@
+namespace S7.Net
+{
+    internal class PLCAddress
+    {
+        private DataType dataType;
+        private int dbNumber;
+        private int startByte;
+        private int bitNumber;
+        private VarType varType;
+
+        public DataType DataType
+        {
+            get => dataType;
+            set => dataType = value;
+        }
+
+        public int DbNumber
+        {
+            get => dbNumber;
+            set => dbNumber = value;
+        }
+
+        public int StartByte
+        {
+            get => startByte;
+            set => startByte = value;
+        }
+
+        public int BitNumber
+        {
+            get => bitNumber;
+            set => bitNumber = value;
+        }
+
+        public VarType VarType
+        {
+            get => varType;
+            set => varType = value;
+        }
+
+        public PLCAddress(string address)
+        {
+            Parse(address, out dataType, out dbNumber, out varType, out startByte, out bitNumber);
+        }
+
+        public static void Parse(string input, out DataType dataType, out int dbNumber, out VarType varType, out int address, out int bitNumber)
+        {
+            bitNumber = -1;
+            dbNumber = 0;
+
+            switch (input.Substring(0, 2))
+            {
+                case "DB":
+                    string[] strings = input.Split(new char[] { '.' });
+                    if (strings.Length < 2)
+                        throw new InvalidAddressException("To few periods for DB address");
+
+                    dataType = DataType.DataBlock;
+                    dbNumber = int.Parse(strings[0].Substring(2));
+                    address = int.Parse(strings[1].Substring(3));
+
+                    string dbType = strings[1].Substring(0, 3);
+                    switch (dbType)
+                    {
+                        case "DBB":
+                            varType = VarType.Byte;
+                            return;
+                        case "DBW":
+                            varType = VarType.Word;
+                            return;
+                        case "DBD":
+                            varType = VarType.DWord;
+                            return;
+                        case "DBX":
+                            bitNumber = int.Parse(strings[2]);
+                            if (bitNumber > 7)
+                                throw new InvalidAddressException("Bit can only be 0-7");
+                            varType = VarType.Bit;
+                            return;
+                        default:
+                            throw new InvalidAddressException();
+                    }
+                case "IB":
+                case "EB":
+                    // Input byte
+                    dataType = DataType.Input;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Byte;
+                    return;
+                case "IW":
+                case "EW":
+                    // Input word
+                    dataType = DataType.Input;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Word;
+                    return;
+                case "ID":
+                case "ED":
+                    // Input double-word
+                    dataType = DataType.Input;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.DWord;
+                    return;
+                case "QB":
+                case "AB":
+                case "OB":
+                    // Output byte
+                    dataType = DataType.Output;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Byte;
+                    return;
+                case "QW":
+                case "AW":
+                case "OW":
+                    // Output word
+                    dataType = DataType.Output;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Word;
+                    return;
+                case "QD":
+                case "AD":
+                case "OD":
+                    // Output double-word
+                    dataType = DataType.Output;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.DWord;
+                    return;
+                case "MB":
+                    // Memory byte
+                    dataType = DataType.Memory;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Byte;
+                    return;
+                case "MW":
+                    // Memory word
+                    dataType = DataType.Memory;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.Word;
+                    return;
+                case "MD":
+                    // Memory double-word
+                    dataType = DataType.Memory;
+                    dbNumber = 0;
+                    address = int.Parse(input.Substring(2));
+                    varType = VarType.DWord;
+                    return;
+                default:
+                    switch (input.Substring(0, 1))
+                    {
+                        case "E":
+                        case "I":
+                            // Input
+                            dataType = DataType.Input;
+                            varType = VarType.Bit;
+                            break;
+                        case "Q":
+                        case "A":
+                        case "O":
+                            // Output
+                            dataType = DataType.Output;
+                            varType = VarType.Bit;
+                            break;
+                        case "M":
+                            // Memory
+                            dataType = DataType.Memory;
+                            varType = VarType.Bit;
+                            break;
+                        case "T":
+                            // Timer
+                            dataType = DataType.Timer;
+                            dbNumber = 0;
+                            address = int.Parse(input.Substring(1));
+                            varType = VarType.Timer;
+                            return;
+                        case "Z":
+                        case "C":
+                            // Counter
+                            dataType = DataType.Counter;
+                            dbNumber = 0;
+                            address = int.Parse(input.Substring(1));
+                            varType = VarType.Counter;
+                            return;
+                        default:
+                            throw new InvalidAddressException(string.Format("{0} is not a valid address", input.Substring(0, 1)));
+                    }
+
+                    string txt2 = input.Substring(1);
+                    if (txt2.IndexOf(".") == -1)
+                        throw new InvalidAddressException("To few periods for DB address");
+
+                    address = int.Parse(txt2.Substring(0, txt2.IndexOf(".")));
+                    bitNumber = int.Parse(txt2.Substring(txt2.IndexOf(".") + 1));
+                    if (bitNumber > 7)
+                        throw new InvalidAddressException("Bit can only be 0-7");
+                    return;
+            }
+        }
+    }
+}

S7.Net/PLCExceptions.cs

@@ -0,0 +1,113 @@
+using System;
+#if NET_FULL
+using System.Runtime.Serialization;    
+#endif
+
+
+namespace S7.Net
+{
+    public class WrongNumberOfBytesException : Exception
+    {
+        public WrongNumberOfBytesException() : base()
+        {
+        }
+
+        public WrongNumberOfBytesException(string message) : base(message)
+        {
+        }
+
+        public WrongNumberOfBytesException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+        #if NET_FULL
+        protected WrongNumberOfBytesException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+        #endif
+    }
+
+    public class InvalidAddressException : Exception
+    {
+        public InvalidAddressException() : base ()
+        {
+        }
+
+        public InvalidAddressException(string message) : base(message)
+        {
+        }
+
+        public InvalidAddressException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+        #if NET_FULL
+        protected InvalidAddressException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+        #endif
+    }
+
+    public class InvalidVariableTypeException : Exception
+    {
+        public InvalidVariableTypeException() : base()
+        {
+        }
+
+        public InvalidVariableTypeException(string message) : base(message)
+        {
+        }
+
+        public InvalidVariableTypeException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+        #if NET_FULL
+        protected InvalidVariableTypeException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+        #endif
+    }
+
+    public class TPKTInvalidException : Exception
+    {
+        public TPKTInvalidException() : base()
+        {
+        }
+
+        public TPKTInvalidException(string message) : base(message)
+        {
+        }
+
+        public TPKTInvalidException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+        #if NET_FULL
+        protected TPKTInvalidException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+        #endif
+    }
+
+    public class TPDUInvalidException : Exception
+    {
+        public TPDUInvalidException() : base()
+        {
+        }
+
+        public TPDUInvalidException(string message) : base(message)
+        {
+        }
+
+        public TPDUInvalidException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+#if NET_FULL
+        protected TPDUInvalidException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+#endif
+    }
+}

S7.Net/PLCHelpers.cs

@@ -0,0 +1,370 @@
+using S7.Net.Helper;
+using S7.Net.Protocol.S7;
+using S7.Net.Types;
+using System.Collections.Generic;
+using System.Linq;
+using DateTime = S7.Net.Types.DateTime;
+
+namespace S7.Net
+{
+    public partial class Plc
+    {
+        private static void WriteTpktHeader(System.IO.MemoryStream stream, int length)
+        {
+            stream.Write(new byte[] { 0x03, 0x00 });
+            stream.Write(Word.ToByteArray((ushort) length));
+        }
+
+        private static void WriteDataHeader(System.IO.MemoryStream stream)
+        {
+            stream.Write(new byte[] { 0x02, 0xf0, 0x80 });
+        }
+
+        private static void WriteS7Header(System.IO.MemoryStream stream, byte messageType, int parameterLength, int dataLength)
+        {
+            stream.WriteByte(0x32); // S7 protocol ID
+            stream.WriteByte(messageType); // Message type
+            stream.Write(new byte[] { 0x00, 0x00 }); // Reserved
+            stream.Write(new byte[] { 0x00, 0x00 }); // PDU ref
+            stream.Write(Word.ToByteArray((ushort) parameterLength));
+            stream.Write(Word.ToByteArray((ushort) dataLength));
+        }
+
+        /// <summary>
+        /// Creates the header to read bytes from the PLC.
+        /// </summary>
+        /// <param name="stream">The stream to write to.</param>
+        /// <param name="amount">The number of items to read.</param>
+        private static void WriteReadHeader(System.IO.MemoryStream stream, int amount = 1)
+        {
+            // Header size 19, 12 bytes per item
+            WriteTpktHeader(stream, 19 + 12 * amount);
+            WriteDataHeader(stream);
+            WriteS7Header(stream, 0x01, 2 + 12 * amount, 0);
+            // Function code: read request
+            stream.WriteByte(0x04);
+            //amount of requests
+            stream.WriteByte((byte)amount);
+        }
+
+        private static void WriteUserDataHeader(System.IO.MemoryStream stream, int parameterLength, int dataLength)
+        {
+            const byte s7MessageTypeUserData = 0x07;
+
+            WriteTpktHeader(stream, 17 + parameterLength + dataLength);
+            WriteDataHeader(stream);
+            WriteS7Header(stream, s7MessageTypeUserData, parameterLength, dataLength);
+        }
+
+        private static void WriteUserDataRequest(System.IO.MemoryStream stream, byte functionGroup, byte subFunction, int dataLength)
+        {
+            WriteUserDataHeader(stream, 8, dataLength);
+
+            // Parameter
+            const byte userDataMethodRequest = 0x11;
+            const byte userDataTypeRequest = 0x4;
+
+            // Parameter head
+            stream.Write(new byte[] { 0x00, 0x01, 0x12 });
+            // Parameter length
+            stream.WriteByte(0x04);
+            // Method
+            stream.WriteByte(userDataMethodRequest);
+            // Type / function group
+            stream.WriteByte((byte)(userDataTypeRequest << 4 | (functionGroup & 0x0f)));
+            // Subfunction
+            stream.WriteByte(subFunction);
+            // Sequence number
+            stream.WriteByte(0);
+        }
+
+        private static void WriteSzlReadRequest(System.IO.MemoryStream stream, ushort szlId, ushort szlIndex)
+        {
+            // Parameter
+            const byte szlFunctionGroupCpuFunctions = 0b100;
+            const byte subFunctionReadSzl = 0x01;
+
+            WriteUserDataRequest(stream, szlFunctionGroupCpuFunctions, subFunctionReadSzl, 8);
+
+            // Data
+            const byte success = 0xff;
+            const byte transportSizeOctetString = 0x09;
+
+            // Return code
+            stream.WriteByte(success);
+            // Transport size
+            stream.WriteByte(transportSizeOctetString);
+            // Length
+            stream.Write(Word.ToByteArray(4));
+            // SZL-ID
+            stream.Write(Word.ToByteArray(szlId));
+            // SZL-Index
+            stream.Write(Word.ToByteArray(szlIndex));
+        }
+
+        /// <summary>
+        /// Create the bytes-package to request data from the PLC. You have to specify the memory type (dataType),
+        /// the address of the memory, the address of the byte and the bytes count.
+        /// </summary>
+        /// <param name="stream">The stream to write the read data request to.</param>
+        /// <param name="dataType">MemoryType (DB, Timer, Counter, etc.)</param>
+        /// <param name="db">Address of the memory to be read</param>
+        /// <param name="startByteAdr">Start address of the byte</param>
+        /// <param name="count">Number of bytes to be read</param>
+        /// <returns></returns>
+        private static void BuildReadDataRequestPackage(System.IO.MemoryStream stream, DataType dataType, int db, int startByteAdr, int count = 1)
+        {
+            //single data req = 12
+            stream.Write(new byte[] { 0x12, 0x0a, 0x10 });
+            switch (dataType)
+            {
+                case DataType.Timer:
+                case DataType.Counter:
+                    stream.WriteByte((byte)dataType);
+                    break;
+                default:
+                    stream.WriteByte(0x02);
+                    break;
+            }
+
+            stream.Write(Word.ToByteArray((ushort)(count)));
+            stream.Write(Word.ToByteArray((ushort)(db)));
+            stream.WriteByte((byte)dataType);
+            var overflow = (int)(startByteAdr * 8 / 0xffffU); // handles words with address bigger than 8191
+            stream.WriteByte((byte)overflow);
+            switch (dataType)
+            {
+                case DataType.Timer:
+                case DataType.Counter:
+                    stream.Write(Word.ToByteArray((ushort)(startByteAdr)));
+                    break;
+                default:
+                    stream.Write(Word.ToByteArray((ushort)((startByteAdr) * 8)));
+                    break;
+            }
+        }
+
+        /// <summary>
+        /// Given a S7 variable type (Bool, Word, DWord, etc.), it converts the bytes in the appropriate C# format.
+        /// </summary>
+        /// <param name="varType"></param>
+        /// <param name="bytes"></param>
+        /// <param name="varCount"></param>
+        /// <param name="bitAdr"></param>
+        /// <returns></returns>
+        private object? ParseBytes(VarType varType, byte[] bytes, int varCount, byte bitAdr = 0)
+        {
+            if (bytes == null || bytes.Length == 0)
+                return null;
+
+            switch (varType)
+            {
+                case VarType.Byte:
+                    if (varCount == 1)
+                        return bytes[0];
+                    else
+                        return bytes;
+                case VarType.Word:
+                    if (varCount == 1)
+                        return Word.FromByteArray(bytes);
+                    else
+                        return Word.ToArray(bytes);
+                case VarType.Int:
+                    if (varCount == 1)
+                        return Int.FromByteArray(bytes);
+                    else
+                        return Int.ToArray(bytes);
+                case VarType.DWord:
+                    if (varCount == 1)
+                        return DWord.FromByteArray(bytes);
+                    else
+                        return DWord.ToArray(bytes);
+                case VarType.DInt:
+                    if (varCount == 1)
+                        return DInt.FromByteArray(bytes);
+                    else
+                        return DInt.ToArray(bytes);
+                case VarType.Real:
+                    if (varCount == 1)
+                        return Types.Real.FromByteArray(bytes);
+                    else
+                        return Types.Real.ToArray(bytes);
+                case VarType.LReal:
+                    if (varCount == 1)
+                        return Types.LReal.FromByteArray(bytes);
+                    else
+                        return Types.LReal.ToArray(bytes);
+
+                case VarType.String:
+                    return Types.String.FromByteArray(bytes);
+                case VarType.S7String:
+                    return S7String.FromByteArray(bytes);
+                case VarType.S7WString:
+                    return S7WString.FromByteArray(bytes);
+
+                case VarType.Timer:
+                    if (varCount == 1)
+                        return Timer.FromByteArray(bytes);
+                    else
+                        return Timer.ToArray(bytes);
+                case VarType.Counter:
+                    if (varCount == 1)
+                        return Counter.FromByteArray(bytes);
+                    else
+                        return Counter.ToArray(bytes);
+                case VarType.Bit:
+                    if (varCount == 1)
+                    {
+                        if (bitAdr > 7)
+                            return null;
+                        else
+                            return Bit.FromByte(bytes[0], bitAdr);
+                    }
+                    else
+                    {
+                        return Bit.ToBitArray(bytes, varCount);
+                    }
+                case VarType.DateTime:
+                    if (varCount == 1)
+                    {
+                        return DateTime.FromByteArray(bytes);
+                    }
+                    else
+                    {
+                        return DateTime.ToArray(bytes);
+                    }
+                case VarType.DateTimeLong:
+                    if (varCount == 1)
+                    {
+                        return DateTimeLong.FromByteArray(bytes);
+                    }
+                    else
+                    {
+                        return DateTimeLong.ToArray(bytes);
+                    }
+                case VarType.Time:
+                    if (varCount == 1)
+                    {
+                        return TimeSpan.FromByteArray(bytes);
+                    }
+                    else
+                    {
+                        return TimeSpan.ToArray(bytes);
+                    }
+                case VarType.Date:
+                    if (varCount == 1)
+                    {
+                        return Date.FromByteArray(bytes);
+                    }
+                    else
+                    {
+                        return Date.ToArray(bytes);
+                    }
+                default:
+                    return null;
+            }
+        }
+
+        /// <summary>
+        /// Given a S7 <see cref="VarType"/> (Bool, Word, DWord, etc.), it returns how many bytes to read.
+        /// </summary>
+        /// <param name="varType"></param>
+        /// <param name="varCount"></param>
+        /// <returns>Byte lenght of variable</returns>
+        internal static int VarTypeToByteLength(VarType varType, int varCount = 1)
+        {
+            switch (varType)
+            {
+                case VarType.Bit:
+                    return (varCount + 7) / 8;
+                case VarType.Byte:
+                    return (varCount < 1) ? 1 : varCount;
+                case VarType.String:
+                    return varCount;
+                case VarType.S7String:
+                    return ((varCount + 2) & 1) == 1 ? (varCount + 3) : (varCount + 2);
+                case VarType.S7WString:
+                    return (varCount * 2) + 4;
+                case VarType.Word:
+                case VarType.Timer:
+                case VarType.Int:
+                case VarType.Counter:
+                case VarType.Date:
+                    return varCount * 2;
+                case VarType.DWord:
+                case VarType.DInt:
+                case VarType.Real:
+                case VarType.Time:
+                    return varCount * 4;
+                case VarType.LReal:
+                case VarType.DateTime:
+                    return varCount * 8;
+                case VarType.DateTimeLong:
+                    return varCount * 12;
+                default:
+                    return 0;
+            }
+        }
+
+        private byte[] GetS7ConnectionSetup()
+        {
+            return new byte[] {  3, 0, 0, 25, 2, 240, 128, 50, 1, 0, 0, 255, 255, 0, 8, 0, 0, 240, 0, 0, 3, 0, 3,
+                    3, 192 // Use 960 PDU size
+            };
+        }
+
+        private void ParseDataIntoDataItems(byte[] s7data, List<DataItem> dataItems)
+        {
+            int offset = 14;
+            foreach (var dataItem in dataItems)
+            {
+                // check for Return Code = Success
+                if (s7data[offset] != 0xff)
+                    throw new PlcException(ErrorCode.WrongNumberReceivedBytes);
+
+                // to Data bytes
+                offset += 4;
+
+                int byteCnt = VarTypeToByteLength(dataItem.VarType, dataItem.Count);
+                dataItem.Value = ParseBytes(
+                    dataItem.VarType,
+                    s7data.Skip(offset).Take(byteCnt).ToArray(),
+                    dataItem.Count,
+                    dataItem.BitAdr
+                );
+
+                // next Item
+                offset += byteCnt;
+
+                // Always align to even offset
+                if (offset % 2 != 0)
+                    offset++;
+            }
+        }
+
+        private static byte[] BuildReadRequestPackage(IList<DataItemAddress> dataItems)
+        {
+            int packageSize = 19 + (dataItems.Count * 12);
+            var package = new System.IO.MemoryStream(packageSize);
+
+            WriteReadHeader(package, dataItems.Count);
+
+            foreach (var dataItem in dataItems)
+            {
+                BuildReadDataRequestPackage(package, dataItem.DataType, dataItem.DB, dataItem.StartByteAddress, dataItem.ByteLength);
+            }
+
+            return package.ToArray();
+        }
+
+        private static byte[] BuildSzlReadRequestPackage(ushort szlId, ushort szlIndex)
+        {
+            var stream = new System.IO.MemoryStream();
+
+            WriteSzlReadRequest(stream, szlId, szlIndex);
+            stream.SetLength(stream.Position);
+
+            return stream.ToArray();
+        }
+    }
+}

S7.Net/Plc.Clock.cs

@@ -0,0 +1,92 @@
+using System;
+using System.IO;
+using System.Linq;
+using S7.Net.Helper;
+using S7.Net.Types;
+using DateTime = System.DateTime;
+
+namespace S7.Net;
+
+partial class Plc
+{
+    private const byte SzlFunctionGroupTimers = 0x07;
+    private const byte SzlSubFunctionReadClock = 0x01;
+    private const byte SzlSubFunctionWriteClock = 0x02;
+    private const byte TransportSizeOctetString = 0x09;
+    private const int PduErrOffset = 20;
+    private const int UserDataResultOffset = PduErrOffset + 2;
+
+    /// <summary>
+    /// The length in bytes of DateTime stored in the PLC.
+    /// </summary>
+    private const int DateTimeLength = 10;
+
+    private static byte[] BuildClockReadRequest()
+    {
+        var stream = new MemoryStream();
+
+        WriteUserDataRequest(stream, SzlFunctionGroupTimers, SzlSubFunctionReadClock, 4);
+        stream.Write(new byte[] { 0x0a, 0x00, 0x00, 0x00 });
+
+        stream.SetLength(stream.Position);
+        return stream.ToArray();
+    }
+
+    private static DateTime ParseClockReadResponse(byte[] message)
+    {
+        const int udLenOffset = UserDataResultOffset + 2;
+        const int udValueOffset = udLenOffset + 2;
+        const int dateTimeSkip = 2;
+
+        AssertPduResult(message);
+        AssertUserDataResult(message, 0xff);
+
+        var len = Word.FromByteArray(message.Skip(udLenOffset).Take(2).ToArray());
+        if (len != DateTimeLength)
+        {
+            throw new Exception($"Unexpected response length {len}, expected {DateTimeLength}.");
+        }
+
+        // Skip first 2 bytes from date time value because DateTime.FromByteArray doesn't parse them.
+        return Types.DateTime.FromByteArray(message.Skip(udValueOffset + dateTimeSkip)
+            .Take(DateTimeLength - dateTimeSkip).ToArray());
+    }
+
+    private static byte[] BuildClockWriteRequest(DateTime value)
+    {
+        var stream = new MemoryStream();
+
+        WriteUserDataRequest(stream, SzlFunctionGroupTimers, SzlSubFunctionWriteClock, 14);
+        stream.Write(new byte[] { 0xff, TransportSizeOctetString, 0x00, DateTimeLength });
+        // Start of DateTime value, DateTime.ToByteArray only serializes the final 8 bytes
+        stream.Write(new byte[] { 0x00, 0x19 });
+        stream.Write(Types.DateTime.ToByteArray(value));
+
+        stream.SetLength(stream.Position);
+        return stream.ToArray();
+    }
+
+    private static void ParseClockWriteResponse(byte[] message)
+    {
+        AssertPduResult(message);
+        AssertUserDataResult(message, 0x0a);
+    }
+
+    private static void AssertPduResult(byte[] message)
+    {
+        var pduErr = Word.FromByteArray(message.Skip(PduErrOffset).Take(2).ToArray());
+        if (pduErr != 0)
+        {
+            throw new Exception($"Response from PLC indicates error 0x{pduErr:X4}.");
+        }
+    }
+
+    private static void AssertUserDataResult(byte[] message, byte expected)
+    {
+        var dtResult = message[UserDataResultOffset];
+        if (dtResult != expected)
+        {
+            throw new Exception($"Response from PLC was 0x{dtResult:X2}, expected 0x{expected:X2}.");
+        }
+    }
+}

S7.Net/PlcAsynchronous.cs

@@ -0,0 +1,645 @@
+using S7.Net.Types;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+using S7.Net.Protocol;
+using System.Threading;
+using S7.Net.Protocol.S7;
+
+namespace S7.Net
+{
+    /// <summary>
+    /// Creates an instance of S7.Net driver
+    /// </summary>
+    public partial class Plc
+    {
+        /// <summary>
+        /// Connects to the PLC and performs a COTP ConnectionRequest and S7 CommunicationSetup.
+        /// </summary>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that the cancellation will not affect opening the socket in any way and only affects data transfers for configuring the connection after the socket connection is successfully established.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous open operation.</returns>
+        public async Task OpenAsync(CancellationToken cancellationToken = default)
+        {
+            var stream = await ConnectAsync(cancellationToken).ConfigureAwait(false);
+            try
+            {
+                await queue.Enqueue(async () =>
+                {
+                    cancellationToken.ThrowIfCancellationRequested();
+                    await EstablishConnection(stream, cancellationToken).ConfigureAwait(false);
+                    _stream = stream;
+
+                    return default(object);
+                }).ConfigureAwait(false);
+            }
+            catch (Exception)
+            {
+                stream.Dispose();
+                throw;
+            }
+        }
+
+        private async Task<NetworkStream> ConnectAsync(CancellationToken cancellationToken)
+        {
+            tcpClient = new TcpClient();
+            ConfigureConnection();
+
+#if NET5_0_OR_GREATER
+            await tcpClient.ConnectAsync(IP, Port, cancellationToken).ConfigureAwait(false);
+#else
+            await tcpClient.ConnectAsync(IP, Port).ConfigureAwait(false);
+#endif
+            return tcpClient.GetStream();
+        }
+
+        private async Task EstablishConnection(Stream stream, CancellationToken cancellationToken)
+        {
+            await RequestConnection(stream, cancellationToken).ConfigureAwait(false);
+            await SetupConnection(stream, cancellationToken).ConfigureAwait(false);
+        }
+
+        private async Task RequestConnection(Stream stream, CancellationToken cancellationToken)
+        {
+            var requestData = ConnectionRequest.GetCOTPConnectionRequest(TsapPair);
+            var response = await NoLockRequestTpduAsync(stream, requestData, cancellationToken).ConfigureAwait(false);
+
+            if (response.PDUType != COTP.PduType.ConnectionConfirmed)
+            {
+                throw new InvalidDataException("Connection request was denied", response.TPkt.Data, 1, 0x0d);
+            }
+        }
+
+        private async Task SetupConnection(Stream stream, CancellationToken cancellationToken)
+        {
+            var setupData = GetS7ConnectionSetup();
+
+            var s7data = await NoLockRequestTsduAsync(stream, setupData, 0, setupData.Length, cancellationToken)
+                .ConfigureAwait(false);
+
+            if (s7data.Length < 2)
+                throw new WrongNumberOfBytesException("Not enough data received in response to Communication Setup");
+
+            //Check for S7 Ack Data
+            if (s7data[1] != 0x03)
+                throw new InvalidDataException("Error reading Communication Setup response", s7data, 1, 0x03);
+
+            if (s7data.Length < 20)
+                throw new WrongNumberOfBytesException("Not enough data received in response to Communication Setup");
+
+            // TODO: check if this should not rather be UInt16.
+            MaxPDUSize = s7data[18] * 256 + s7data[19];
+        }
+
+        /// <summary>
+        /// Reads a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="count">Byte count, if you want to read 120 bytes, set this to 120.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>Returns the bytes in an array</returns>
+        public async Task<byte[]> ReadBytesAsync(DataType dataType, int db, int startByteAdr, int count, CancellationToken cancellationToken = default)
+        {
+            var resultBytes = new byte[count];
+
+            await ReadBytesAsync(resultBytes, dataType, db, startByteAdr, cancellationToken).ConfigureAwait(false);
+
+            return resultBytes;
+        }
+
+        /// <summary>
+        /// Reads a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="buffer">Buffer to receive the read bytes. The <see cref="Memory{T}.Length"/> determines the number of bytes to read.</param>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>Returns the bytes in an array</returns>
+        public async Task ReadBytesAsync(Memory<byte> buffer, DataType dataType, int db, int startByteAdr, CancellationToken cancellationToken = default)
+        {
+            int index = 0;
+            while (buffer.Length > 0)
+            {
+                //This works up to MaxPDUSize-1 on SNAP7. But not MaxPDUSize-0.
+                var maxToRead = Math.Min(buffer.Length, MaxPDUSize - 18);
+                await ReadBytesWithSingleRequestAsync(dataType, db, startByteAdr + index, buffer.Slice(0, maxToRead), cancellationToken).ConfigureAwait(false);
+                buffer = buffer.Slice(maxToRead);
+                index += maxToRead;
+            }
+        }
+
+        /// <summary>
+        /// Read and decode a certain number of bytes of the "VarType" provided.
+        /// This can be used to read multiple consecutive variables of the same type (Word, DWord, Int, etc).
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="varType">Type of the variable/s that you are reading</param>
+        /// <param name="bitAdr">Address of bit. If you want to read DB1.DBX200.6, set 6 to this parameter.</param>
+        /// <param name="varCount"></param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        public async Task<object?> ReadAsync(DataType dataType, int db, int startByteAdr, VarType varType, int varCount, byte bitAdr = 0, CancellationToken cancellationToken = default)
+        {
+            int cntBytes = VarTypeToByteLength(varType, varCount);
+            byte[] bytes = await ReadBytesAsync(dataType, db, startByteAdr, cntBytes, cancellationToken).ConfigureAwait(false);
+            return ParseBytes(varType, bytes, varCount, bitAdr);
+        }
+
+        /// <summary>
+        /// Reads a single variable from the PLC, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="variable">Input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>Returns an object that contains the value. This object must be cast accordingly.</returns>
+        public async Task<object?> ReadAsync(string variable, CancellationToken cancellationToken = default)
+        {
+            var adr = new PLCAddress(variable);
+            return await ReadAsync(adr.DataType, adr.DbNumber, adr.StartByte, adr.VarType, 1, (byte)adr.BitNumber, cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a struct in C#, starting from a certain address, and return an object that can be casted to the struct.
+        /// </summary>
+        /// <param name="structType">Type of the struct to be readed (es.: TypeOf(MyStruct)).</param>
+        /// <param name="db">Address of the DB.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>Returns a struct that must be cast.</returns>
+        public async Task<object?> ReadStructAsync(Type structType, int db, int startByteAdr = 0, CancellationToken cancellationToken = default)
+        {
+            int numBytes = Types.Struct.GetStructSize(structType);
+            // now read the package
+            var resultBytes = await ReadBytesAsync(DataType.DataBlock, db, startByteAdr, numBytes, cancellationToken).ConfigureAwait(false);
+
+            // and decode it
+            return Types.Struct.FromBytes(structType, resultBytes);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a struct in C#, starting from a certain address, and returns the struct or null if nothing was read.
+        /// </summary>
+        /// <typeparam name="T">The struct type</typeparam>
+        /// <param name="db">Address of the DB.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>Returns a nulable struct. If nothing was read null will be returned.</returns>
+        public async Task<T?> ReadStructAsync<T>(int db, int startByteAdr = 0, CancellationToken cancellationToken = default) where T : struct
+        {
+            return await ReadStructAsync(typeof(T), db, startByteAdr, cancellationToken).ConfigureAwait(false) as T?;
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified.
+        /// </summary>
+        /// <param name="sourceClass">Instance of the class that will store the values</param>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>The number of read bytes</returns>
+        public async Task<Tuple<int, object>> ReadClassAsync(object sourceClass, int db, int startByteAdr = 0, CancellationToken cancellationToken = default)
+        {
+            int numBytes = (int)Class.GetClassSize(sourceClass);
+            if (numBytes <= 0)
+            {
+                throw new Exception("The size of the class is less than 1 byte and therefore cannot be read");
+            }
+
+            // now read the package
+            var resultBytes = await ReadBytesAsync(DataType.DataBlock, db, startByteAdr, numBytes, cancellationToken).ConfigureAwait(false);
+            // and decode it
+            Class.FromBytes(sourceClass, resultBytes);
+
+            return new Tuple<int, object>(resultBytes.Length, sourceClass);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified. To instantiate the class defined by the generic
+        /// type, the class needs a default constructor.
+        /// </summary>
+        /// <typeparam name="T">The class that will be instantiated. Requires a default constructor</typeparam>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>An instance of the class with the values read from the PLC. If no data has been read, null will be returned</returns>
+        public async Task<T?> ReadClassAsync<T>(int db, int startByteAdr = 0, CancellationToken cancellationToken = default) where T : class
+        {
+            return await ReadClassAsync(() => Activator.CreateInstance<T>(), db, startByteAdr, cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified.
+        /// </summary>
+        /// <typeparam name="T">The class that will be instantiated</typeparam>
+        /// <param name="classFactory">Function to instantiate the class</param>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>An instance of the class with the values read from the PLC. If no data has been read, null will be returned</returns>
+        public async Task<T?> ReadClassAsync<T>(Func<T> classFactory, int db, int startByteAdr = 0, CancellationToken cancellationToken = default) where T : class
+        {
+            var instance = classFactory();
+            var res = await ReadClassAsync(instance, db, startByteAdr, cancellationToken).ConfigureAwait(false);
+            int readBytes = res.Item1;
+            if (readBytes <= 0)
+            {
+                return null;
+            }
+
+            return (T)res.Item2;
+        }
+
+        /// <summary>
+        /// Reads multiple vars in a single request.
+        /// You have to create and pass a list of DataItems and you obtain in response the same list with the values.
+        /// Values are stored in the property "Value" of the dataItem and are already converted.
+        /// If you don't want the conversion, just create a dataItem of bytes.
+        /// The number of DataItems as well as the total size of the requested data can not exceed a certain limit (protocol restriction).
+        /// </summary>
+        /// <param name="dataItems">List of dataitems that contains the list of variables that must be read.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        public async Task<List<DataItem>> ReadMultipleVarsAsync(List<DataItem> dataItems, CancellationToken cancellationToken = default)
+        {
+            //Snap7 seems to choke on PDU sizes above 256 even if snap7
+            //replies with bigger PDU size in connection setup.
+            AssertPduSizeForRead(dataItems);
+
+            try
+            {
+                var dataToSend = BuildReadRequestPackage(dataItems.Select(d => DataItem.GetDataItemAddress(d)).ToList());
+                var s7data = await RequestTsduAsync(dataToSend, cancellationToken);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+
+                ParseDataIntoDataItems(s7data, dataItems);
+            }
+            catch (SocketException socketException)
+            {
+                throw new PlcException(ErrorCode.ReadData, socketException);
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.ReadData, exc);
+            }
+            return dataItems;
+        }
+
+        /// <summary>
+        /// Read the PLC clock value.
+        /// </summary>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous operation, with it's result set to the current PLC time on completion.</returns>
+        public async Task<System.DateTime> ReadClockAsync(CancellationToken cancellationToken = default)
+        {
+            var request = BuildClockReadRequest();
+            var response = await RequestTsduAsync(request, cancellationToken);
+
+            return ParseClockReadResponse(response);
+        }
+
+        /// <summary>
+        /// Write the PLC clock value.
+        /// </summary>
+        /// <param name="value">The date and time to set the PLC clock to</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous operation.</returns>
+        public async Task WriteClockAsync(System.DateTime value, CancellationToken cancellationToken = default)
+        {
+            var request = BuildClockWriteRequest(value);
+            var response = await RequestTsduAsync(request, cancellationToken);
+
+            ParseClockWriteResponse(response);
+        }
+
+        /// <summary>
+        /// Read the current status from the PLC. A value of 0x08 indicates the PLC is in run status, regardless of the PLC type.
+        /// </summary>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous operation, with it's result set to the current PLC status on completion.</returns>
+        public async Task<byte> ReadStatusAsync(CancellationToken cancellationToken = default)
+        {
+            var dataToSend = BuildSzlReadRequestPackage(0x0424, 0);
+            var s7data = await RequestTsduAsync(dataToSend, cancellationToken);
+
+            return (byte) (s7data[37] & 0x0f);
+        }
+
+        /// <summary>
+        /// Write a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the write was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public Task WriteBytesAsync(DataType dataType, int db, int startByteAdr, byte[] value, CancellationToken cancellationToken = default)
+        {
+            return WriteBytesAsync(dataType, db, startByteAdr, value.AsMemory(), cancellationToken);
+        }
+
+        /// <summary>
+        /// Write a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the write was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteBytesAsync(DataType dataType, int db, int startByteAdr, ReadOnlyMemory<byte> value, CancellationToken cancellationToken = default)
+        {
+            int localIndex = 0;
+            while (value.Length > 0)
+            {
+                var maxToWrite = (int)Math.Min(value.Length, MaxPDUSize - 35);
+                await WriteBytesWithASingleRequestAsync(dataType, db, startByteAdr + localIndex, value.Slice(0, maxToWrite), cancellationToken).ConfigureAwait(false);
+                value = value.Slice(maxToWrite);
+                localIndex += maxToWrite;
+            }
+        }
+
+        /// <summary>
+        /// Write a single bit from a DB with the specified index.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteBitAsync(DataType dataType, int db, int startByteAdr, int bitAdr, bool value, CancellationToken cancellationToken = default)
+        {
+            if (bitAdr < 0 || bitAdr > 7)
+                throw new InvalidAddressException(string.Format("Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid", bitAdr));
+
+            await WriteBitWithASingleRequestAsync(dataType, db, startByteAdr, bitAdr, value, cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Write a single bit from a DB with the specified index.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteBitAsync(DataType dataType, int db, int startByteAdr, int bitAdr, int value, CancellationToken cancellationToken = default)
+        {
+            if (value < 0 || value > 1)
+                throw new ArgumentException("Value must be 0 or 1", nameof(value));
+
+            await WriteBitAsync(dataType, db, startByteAdr, bitAdr, value == 1, cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Takes in input an object and tries to parse it to an array of values. This can be used to write many data, all of the same type.
+        /// You must specify the memory area type, memory are address, byte start address and bytes count.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. The lenght of this parameter can't be higher than 200. If you need more, use recursion.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteAsync(DataType dataType, int db, int startByteAdr, object value, int bitAdr = -1, CancellationToken cancellationToken = default)
+        {
+            if (bitAdr != -1)
+            {
+                //Must be writing a bit value as bitAdr is specified
+                if (value is bool boolean)
+                {
+                    await WriteBitAsync(dataType, db, startByteAdr, bitAdr, boolean, cancellationToken).ConfigureAwait(false);
+                }
+                else if (value is int intValue)
+                {
+                    if (intValue < 0 || intValue > 7)
+                        throw new ArgumentOutOfRangeException(
+                            string.Format(
+                                "Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid",
+                                bitAdr), nameof(bitAdr));
+
+                    await WriteBitAsync(dataType, db, startByteAdr, bitAdr, intValue == 1, cancellationToken).ConfigureAwait(false);
+                }
+                else throw new ArgumentException("Value must be a bool or an int to write a bit", nameof(value));
+            }
+            else await WriteBytesAsync(dataType, db, startByteAdr, Serialization.SerializeValue(value), cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Writes a single variable from the PLC, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// </summary>
+        /// <param name="variable">Input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.</param>
+        /// <param name="value">Value to be written to the PLC</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteAsync(string variable, object value, CancellationToken cancellationToken = default)
+        {
+            var adr = new PLCAddress(variable);
+            await WriteAsync(adr.DataType, adr.DbNumber, adr.StartByte, value, adr.BitNumber, cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Writes a C# struct to a DB in the PLC
+        /// </summary>
+        /// <param name="structValue">The struct to be written</param>
+        /// <param name="db">Db address</param>
+        /// <param name="startByteAdr">Start bytes on the PLC</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteStructAsync(object structValue, int db, int startByteAdr = 0, CancellationToken cancellationToken = default)
+        {
+            var bytes = Struct.ToBytes(structValue).ToList();
+            await WriteBytesAsync(DataType.DataBlock, db, startByteAdr, bytes.ToArray(), cancellationToken).ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Writes a C# class to a DB in the PLC
+        /// </summary>
+        /// <param name="classValue">The class to be written</param>
+        /// <param name="db">Db address</param>
+        /// <param name="startByteAdr">Start bytes on the PLC</param>
+        /// <param name="cancellationToken">The token to monitor for cancellation requests. The default value is None.
+        /// Please note that cancellation is advisory/cooperative and will not lead to immediate cancellation in all cases.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        public async Task WriteClassAsync(object classValue, int db, int startByteAdr = 0, CancellationToken cancellationToken = default)
+        {
+            byte[] bytes = new byte[(int)Class.GetClassSize(classValue)];
+            Types.Class.ToBytes(classValue, bytes);
+            await WriteBytesAsync(DataType.DataBlock, db, startByteAdr, bytes, cancellationToken).ConfigureAwait(false);
+        }
+
+        private async Task ReadBytesWithSingleRequestAsync(DataType dataType, int db, int startByteAdr, Memory<byte> buffer, CancellationToken cancellationToken)
+        {
+            var dataToSend = BuildReadRequestPackage(new[] { new DataItemAddress(dataType, db, startByteAdr, buffer.Length) });
+
+            var s7data = await RequestTsduAsync(dataToSend, cancellationToken);
+            AssertReadResponse(s7data, buffer.Length);
+
+            s7data.AsSpan(18, buffer.Length).CopyTo(buffer.Span);
+        }
+
+        /// <summary>
+        /// Write DataItem(s) to the PLC. Throws an exception if the response is invalid
+        /// or when the PLC reports errors for item(s) written.
+        /// </summary>
+        /// <param name="dataItems">The DataItem(s) to write to the PLC.</param>
+        /// <returns>Task that completes when response from PLC is parsed.</returns>
+        public async Task WriteAsync(params DataItem[] dataItems)
+        {
+            AssertPduSizeForWrite(dataItems);
+
+            var message = new ByteArray();
+            var length = S7WriteMultiple.CreateRequest(message, dataItems);
+
+            var response = await RequestTsduAsync(message.Array, 0, length).ConfigureAwait(false);
+
+            S7WriteMultiple.ParseResponse(response, response.Length, dataItems);
+        }
+
+        /// <summary>
+        /// Writes up to 200 bytes to the PLC. You must specify the memory area type, memory are address, byte start address and bytes count.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. The lenght of this parameter can't be higher than 200. If you need more, use recursion.</param>
+        /// <param name="cancellationToken">A cancellation token that can be used to cancel the asynchronous operation.</param>
+        /// <returns>A task that represents the asynchronous write operation.</returns>
+        private async Task WriteBytesWithASingleRequestAsync(DataType dataType, int db, int startByteAdr, ReadOnlyMemory<byte> value, CancellationToken cancellationToken)
+        {
+            try
+            {
+                var dataToSend = BuildWriteBytesPackage(dataType, db, startByteAdr, value.Span);
+                var s7data = await RequestTsduAsync(dataToSend, cancellationToken).ConfigureAwait(false);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.WriteData, exc);
+            }
+        }
+
+        private async Task WriteBitWithASingleRequestAsync(DataType dataType, int db, int startByteAdr, int bitAdr, bool bitValue, CancellationToken cancellationToken)
+        {
+            try
+            {
+                var dataToSend = BuildWriteBitPackage(dataType, db, startByteAdr, bitValue, bitAdr);
+                var s7data = await RequestTsduAsync(dataToSend, cancellationToken).ConfigureAwait(false);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.WriteData, exc);
+            }
+        }
+
+        private Task<byte[]> RequestTsduAsync(byte[] requestData, CancellationToken cancellationToken = default) =>
+            RequestTsduAsync(requestData, 0, requestData.Length, cancellationToken);
+
+        private Task<byte[]> RequestTsduAsync(byte[] requestData, int offset, int length, CancellationToken cancellationToken = default)
+        {
+            var stream = GetStreamIfAvailable();
+
+            return queue.Enqueue(() =>
+                NoLockRequestTsduAsync(stream, requestData, offset, length, cancellationToken));
+        }
+
+        private async Task<COTP.TPDU> NoLockRequestTpduAsync(Stream stream, byte[] requestData,
+            CancellationToken cancellationToken = default)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            try
+            {
+                using var closeOnCancellation = cancellationToken.Register(Close);
+                await stream.WriteAsync(requestData, 0, requestData.Length, cancellationToken).ConfigureAwait(false);
+                return await COTP.TPDU.ReadAsync(stream, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception exc)
+            {
+                if (exc is TPDUInvalidException || exc is TPKTInvalidException)
+                {
+                    Close();
+                }
+
+                throw;
+            }
+        }
+
+        private async Task<byte[]> NoLockRequestTsduAsync(Stream stream, byte[] requestData, int offset, int length,
+            CancellationToken cancellationToken = default)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            try
+            {
+                using var closeOnCancellation = cancellationToken.Register(Close);
+                await stream.WriteAsync(requestData, offset, length, cancellationToken).ConfigureAwait(false);
+                return await COTP.TSDU.ReadAsync(stream, cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception exc)
+            {
+                if (exc is TPDUInvalidException || exc is TPKTInvalidException)
+                {
+                    Close();
+                }
+
+                throw;
+            }
+        }
+    }
+}

S7.Net/PlcException.cs

@@ -0,0 +1,39 @@
+using System;
+
+namespace S7.Net
+{
+    #if NET_FULL
+    [Serializable]
+    #endif
+    public class PlcException : Exception
+    {
+        public ErrorCode ErrorCode { get; }
+
+        public PlcException(ErrorCode errorCode) : this(errorCode, $"PLC communication failed with error '{errorCode}'.")
+        {
+        }
+
+        public PlcException(ErrorCode errorCode, Exception innerException) : this(errorCode, innerException.Message,
+            innerException)
+        {
+        }
+
+        public PlcException(ErrorCode errorCode, string message) : base(message)
+        {
+            ErrorCode = errorCode;
+        }
+
+        public PlcException(ErrorCode errorCode, string message, Exception inner) : base(message, inner)
+        {
+            ErrorCode = errorCode;
+        }
+
+        #if NET_FULL
+        protected PlcException(System.Runtime.Serialization.SerializationInfo info,
+            System.Runtime.Serialization.StreamingContext context) : base(info, context)
+        {
+            ErrorCode = (ErrorCode) info.GetInt32(nameof(ErrorCode));
+        }
+        #endif
+    }
+}

S7.Net/PlcSynchronous.cs

@@ -0,0 +1,538 @@
+using S7.Net.Types;
+using System;
+using System.IO;
+using System.Collections.Generic;
+using S7.Net.Protocol;
+using S7.Net.Helper;
+
+//Implement synchronous methods here
+namespace S7.Net
+{
+    public partial class Plc
+    {
+        /// <summary>
+        /// Connects to the PLC and performs a COTP ConnectionRequest and S7 CommunicationSetup.
+        /// </summary>
+        public void Open()
+        {
+            try
+            {
+                OpenAsync().GetAwaiter().GetResult();
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.ConnectionError,
+                    $"Couldn't establish the connection to {IP}.\nMessage: {exc.Message}", exc);
+            }
+        }
+
+
+        /// <summary>
+        /// Reads a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="count">Byte count, if you want to read 120 bytes, set this to 120.</param>
+        /// <returns>Returns the bytes in an array</returns>
+        public byte[] ReadBytes(DataType dataType, int db, int startByteAdr, int count)
+        {
+            var result = new byte[count];
+
+            ReadBytes(result, dataType, db, startByteAdr);
+
+            return result;
+        }
+
+        /// <summary>
+        /// Reads a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="buffer">Buffer to receive the read bytes. The <see cref="Span{T}.Length"/> determines the number of bytes to read.</param>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>Returns the bytes in an array</returns>
+        public void ReadBytes(Span<byte> buffer, DataType dataType, int db, int startByteAdr)
+        {
+            int index = 0;
+            while (buffer.Length > 0)
+            {
+                //This works up to MaxPDUSize-1 on SNAP7. But not MaxPDUSize-0.
+                var maxToRead = Math.Min(buffer.Length, MaxPDUSize - 18);
+                ReadBytesWithSingleRequest(dataType, db, startByteAdr + index, buffer.Slice(0, maxToRead));
+                buffer = buffer.Slice(maxToRead);
+                index += maxToRead;
+            }
+        }
+
+        /// <summary>
+        /// Read and decode a certain number of bytes of the "VarType" provided.
+        /// This can be used to read multiple consecutive variables of the same type (Word, DWord, Int, etc).
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="varType">Type of the variable/s that you are reading</param>
+        /// <param name="bitAdr">Address of bit. If you want to read DB1.DBX200.6, set 6 to this parameter.</param>
+        /// <param name="varCount"></param>
+        public object? Read(DataType dataType, int db, int startByteAdr, VarType varType, int varCount, byte bitAdr = 0)
+        {
+            int cntBytes = VarTypeToByteLength(varType, varCount);
+            byte[] bytes = ReadBytes(dataType, db, startByteAdr, cntBytes);
+
+            return ParseBytes(varType, bytes, varCount, bitAdr);
+        }
+
+        /// <summary>
+        /// Reads a single variable from the PLC, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="variable">Input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.</param>
+        /// <returns>Returns an object that contains the value. This object must be cast accordingly. If no data has been read, null will be returned</returns>
+        public object? Read(string variable)
+        {
+            var adr = new PLCAddress(variable);
+            return Read(adr.DataType, adr.DbNumber, adr.StartByte, adr.VarType, 1, (byte)adr.BitNumber);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a struct in C#, starting from a certain address, and return an object that can be casted to the struct.
+        /// </summary>
+        /// <param name="structType">Type of the struct to be readed (es.: TypeOf(MyStruct)).</param>
+        /// <param name="db">Address of the DB.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>Returns a struct that must be cast. If no data has been read, null will be returned</returns>
+        public object? ReadStruct(Type structType, int db, int startByteAdr = 0)
+        {
+            int numBytes = Struct.GetStructSize(structType);
+            // now read the package
+            var resultBytes = ReadBytes(DataType.DataBlock, db, startByteAdr, numBytes);
+
+            // and decode it
+            return Struct.FromBytes(structType, resultBytes);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a struct in C#, starting from a certain address, and returns the struct or null if nothing was read.
+        /// </summary>
+        /// <typeparam name="T">The struct type</typeparam>
+        /// <param name="db">Address of the DB.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>Returns a nullable struct. If nothing was read null will be returned.</returns>
+        public T? ReadStruct<T>(int db, int startByteAdr = 0) where T : struct
+        {
+            return ReadStruct(typeof(T), db, startByteAdr) as T?;
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified.
+        /// </summary>
+        /// <param name="sourceClass">Instance of the class that will store the values</param>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>The number of read bytes</returns>
+        public int ReadClass(object sourceClass, int db, int startByteAdr = 0)
+        {
+            int numBytes = (int)Class.GetClassSize(sourceClass);
+            if (numBytes <= 0)
+            {
+                throw new Exception("The size of the class is less than 1 byte and therefore cannot be read");
+            }
+
+            // now read the package
+            var resultBytes = ReadBytes(DataType.DataBlock, db, startByteAdr, numBytes);
+            // and decode it
+            Class.FromBytes(sourceClass, resultBytes);
+            return resultBytes.Length;
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified. To instantiate the class defined by the generic
+        /// type, the class needs a default constructor.
+        /// </summary>
+        /// <typeparam name="T">The class that will be instantiated. Requires a default constructor</typeparam>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>An instance of the class with the values read from the PLC. If no data has been read, null will be returned</returns>
+        public T? ReadClass<T>(int db, int startByteAdr = 0) where T : class
+        {
+            return ReadClass(() => Activator.CreateInstance<T>(), db, startByteAdr);
+        }
+
+        /// <summary>
+        /// Reads all the bytes needed to fill a class in C#, starting from a certain address, and set all the properties values to the value that are read from the PLC.
+        /// This reads only properties, it doesn't read private variable or public variable without {get;set;} specified.
+        /// </summary>
+        /// <typeparam name="T">The class that will be instantiated</typeparam>
+        /// <param name="classFactory">Function to instantiate the class</param>
+        /// <param name="db">Index of the DB; es.: 1 is for DB1</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <returns>An instance of the class with the values read from the PLC. If no data has been read, null will be returned</returns>
+        public T? ReadClass<T>(Func<T> classFactory, int db, int startByteAdr = 0) where T : class
+        {
+            var instance = classFactory();
+            int readBytes = ReadClass(instance, db, startByteAdr);
+            if (readBytes <= 0)
+            {
+                return null;
+            }
+            return instance;
+        }
+
+        /// <summary>
+        /// Write a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the write was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        public void WriteBytes(DataType dataType, int db, int startByteAdr, byte[] value)
+        {
+            WriteBytes(dataType, db, startByteAdr, value.AsSpan());
+        }
+
+        /// <summary>
+        /// Write a number of bytes from a DB starting from a specified index. This handles more than 200 bytes with multiple requests.
+        /// If the write was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        public void WriteBytes(DataType dataType, int db, int startByteAdr, ReadOnlySpan<byte> value)
+        {
+            int localIndex = 0;
+            while (value.Length > 0)
+            {
+                //TODO: Figure out how to use MaxPDUSize here
+                //Snap7 seems to choke on PDU sizes above 256 even if snap7
+                //replies with bigger PDU size in connection setup.
+                var maxToWrite = Math.Min(value.Length, MaxPDUSize - 28);//TODO tested only when the MaxPDUSize is 480
+                WriteBytesWithASingleRequest(dataType, db, startByteAdr + localIndex, value.Slice(0, maxToWrite));
+                value = value.Slice(maxToWrite);
+                localIndex += maxToWrite;
+            }
+        }
+
+        /// <summary>
+        /// Write a single bit from a DB with the specified index.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        /// <param name="value">Bytes to write. If more than 200, multiple requests will be made.</param>
+        public void WriteBit(DataType dataType, int db, int startByteAdr, int bitAdr, bool value)
+        {
+            if (bitAdr < 0 || bitAdr > 7)
+                throw new InvalidAddressException(string.Format("Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid", bitAdr));
+
+            WriteBitWithASingleRequest(dataType, db, startByteAdr, bitAdr, value);
+        }
+
+        /// <summary>
+        /// Write a single bit to a DB with the specified index.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to write DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to write DB1.DBW200, this is 200.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        /// <param name="value">Value to write (0 or 1).</param>
+        public void WriteBit(DataType dataType, int db, int startByteAdr, int bitAdr, int value)
+        {
+            if (value < 0 || value > 1)
+                throw new ArgumentException("Value must be 0 or 1", nameof(value));
+
+            WriteBit(dataType, db, startByteAdr, bitAdr, value == 1);
+        }
+
+        /// <summary>
+        /// Takes in input an object and tries to parse it to an array of values. This can be used to write many data, all of the same type.
+        /// You must specify the memory area type, memory are address, byte start address and bytes count.
+        /// If the read was not successful, check LastErrorCode or LastErrorString.
+        /// </summary>
+        /// <param name="dataType">Data type of the memory area, can be DB, Timer, Counter, Merker(Memory), Input, Output.</param>
+        /// <param name="db">Address of the memory area (if you want to read DB1, this is set to 1). This must be set also for other memory area types: counters, timers,etc.</param>
+        /// <param name="startByteAdr">Start byte address. If you want to read DB1.DBW200, this is 200.</param>
+        /// <param name="value">Bytes to write. The lenght of this parameter can't be higher than 200. If you need more, use recursion.</param>
+        /// <param name="bitAdr">The address of the bit. (0-7)</param>
+        public void Write(DataType dataType, int db, int startByteAdr, object value, int bitAdr = -1)
+        {
+            if (bitAdr != -1)
+            {
+                //Must be writing a bit value as bitAdr is specified
+                if (value is bool boolean)
+                {
+                    WriteBit(dataType, db, startByteAdr, bitAdr, boolean);
+                }
+                else if (value is int intValue)
+                {
+                    if (intValue < 0 || intValue > 7)
+                        throw new ArgumentOutOfRangeException(
+                            string.Format(
+                                "Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid",
+                                bitAdr), nameof(bitAdr));
+
+                    WriteBit(dataType, db, startByteAdr, bitAdr, intValue == 1);
+                }
+                else
+                    throw new ArgumentException("Value must be a bool or an int to write a bit", nameof(value));
+            }
+            else WriteBytes(dataType, db, startByteAdr, Serialization.SerializeValue(value));
+        }
+
+        /// <summary>
+        /// Writes a single variable from the PLC, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// </summary>
+        /// <param name="variable">Input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.</param>
+        /// <param name="value">Value to be written to the PLC</param>
+        public void Write(string variable, object value)
+        {
+            var adr = new PLCAddress(variable);
+            Write(adr.DataType, adr.DbNumber, adr.StartByte, value, adr.BitNumber);
+        }
+
+        /// <summary>
+        /// Writes a C# struct to a DB in the PLC
+        /// </summary>
+        /// <param name="structValue">The struct to be written</param>
+        /// <param name="db">Db address</param>
+        /// <param name="startByteAdr">Start bytes on the PLC</param>
+        public void WriteStruct(object structValue, int db, int startByteAdr = 0)
+        {
+            WriteStructAsync(structValue, db, startByteAdr).GetAwaiter().GetResult();
+        }
+
+        /// <summary>
+        /// Writes a C# class to a DB in the PLC
+        /// </summary>
+        /// <param name="classValue">The class to be written</param>
+        /// <param name="db">Db address</param>
+        /// <param name="startByteAdr">Start bytes on the PLC</param>
+        public void WriteClass(object classValue, int db, int startByteAdr = 0)
+        {
+            WriteClassAsync(classValue, db, startByteAdr).GetAwaiter().GetResult();
+        }
+
+        private void ReadBytesWithSingleRequest(DataType dataType, int db, int startByteAdr, Span<byte> buffer)
+        {
+            try
+            {
+                // first create the header
+                const int packageSize = 19 + 12; // 19 header + 12 for 1 request
+                var dataToSend = new byte[packageSize];
+                var package = new MemoryStream(dataToSend);
+                WriteReadHeader(package);
+                // package.Add(0x02);  // datenart
+                BuildReadDataRequestPackage(package, dataType, db, startByteAdr, buffer.Length);
+
+                var s7data = RequestTsdu(dataToSend);
+                AssertReadResponse(s7data, buffer.Length);
+
+                s7data.AsSpan(18, buffer.Length).CopyTo(buffer);
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.ReadData, exc);
+            }
+        }
+
+        /// <summary>
+        /// Write DataItem(s) to the PLC. Throws an exception if the response is invalid
+        /// or when the PLC reports errors for item(s) written.
+        /// </summary>
+        /// <param name="dataItems">The DataItem(s) to write to the PLC.</param>
+        public void Write(params DataItem[] dataItems)
+        {
+            AssertPduSizeForWrite(dataItems);
+
+            var message = new ByteArray();
+            var length = S7WriteMultiple.CreateRequest(message, dataItems);
+            var response = RequestTsdu(message.Array, 0, length);
+
+            S7WriteMultiple.ParseResponse(response, response.Length, dataItems);
+        }
+
+        private void WriteBytesWithASingleRequest(DataType dataType, int db, int startByteAdr, ReadOnlySpan<byte> value)
+        {
+            try
+            {
+                var dataToSend = BuildWriteBytesPackage(dataType, db, startByteAdr, value);
+                var s7data = RequestTsdu(dataToSend);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.WriteData, exc);
+            }
+        }
+
+        private byte[] BuildWriteBytesPackage(DataType dataType, int db, int startByteAdr, ReadOnlySpan<byte> value)
+        {
+            int varCount = value.Length;
+            // first create the header
+            int packageSize = 35 + varCount;
+            var packageData = new byte[packageSize];
+            var package = new MemoryStream(packageData);
+
+            package.WriteByte(3);
+            package.WriteByte(0);
+            //complete package size
+            package.Write(Int.ToByteArray((short)packageSize));
+            // This overload doesn't allocate the byte array, it refers to assembly's static data segment
+            package.Write(new byte[] { 2, 0xf0, 0x80, 0x32, 1, 0, 0 });
+            package.Write(Word.ToByteArray((ushort)(varCount - 1)));
+            package.Write(new byte[] { 0, 0x0e });
+            package.Write(Word.ToByteArray((ushort)(varCount + 4)));
+            package.Write(new byte[] { 0x05, 0x01, 0x12, 0x0a, 0x10, 0x02 });
+            package.Write(Word.ToByteArray((ushort)varCount));
+            package.Write(Word.ToByteArray((ushort)(db)));
+            package.WriteByte((byte)dataType);
+            var overflow = (int)(startByteAdr * 8 / 0xffffU); // handles words with address bigger than 8191
+            package.WriteByte((byte)overflow);
+            package.Write(Word.ToByteArray((ushort)(startByteAdr * 8)));
+            package.Write(new byte[] { 0, 4 });
+            package.Write(Word.ToByteArray((ushort)(varCount * 8)));
+
+            // now join the header and the data
+            package.Write(value);
+
+            return packageData;
+        }
+
+        private byte[] BuildWriteBitPackage(DataType dataType, int db, int startByteAdr, bool bitValue, int bitAdr)
+        {
+            var value = new[] { bitValue ? (byte)1 : (byte)0 };
+            int varCount = 1;
+            // first create the header
+            int packageSize = 35 + varCount;
+            var packageData = new byte[packageSize];
+            var package = new MemoryStream(packageData);
+
+            package.WriteByte(3);
+            package.WriteByte(0);
+            //complete package size
+            package.Write(Int.ToByteArray((short)packageSize));
+            package.Write(new byte[] { 2, 0xf0, 0x80, 0x32, 1, 0, 0 });
+            package.Write(Word.ToByteArray((ushort)(varCount - 1)));
+            package.Write(new byte[] { 0, 0x0e });
+            package.Write(Word.ToByteArray((ushort)(varCount + 4)));
+            package.Write(new byte[] { 0x05, 0x01, 0x12, 0x0a, 0x10, 0x01 }); //ending 0x01 is used for writing a sinlge bit
+            package.Write(Word.ToByteArray((ushort)varCount));
+            package.Write(Word.ToByteArray((ushort)(db)));
+            package.WriteByte((byte)dataType);
+            var overflow = (int)(startByteAdr * 8 / 0xffffU); // handles words with address bigger than 8191
+            package.WriteByte((byte)overflow);
+            package.Write(Word.ToByteArray((ushort)(startByteAdr * 8 + bitAdr)));
+            package.Write(new byte[] { 0, 0x03 }); //ending 0x03 is used for writing a sinlge bit
+            package.Write(Word.ToByteArray((ushort)(varCount)));
+
+            // now join the header and the data
+            package.Write(value);
+
+            return packageData;
+        }
+
+        private void WriteBitWithASingleRequest(DataType dataType, int db, int startByteAdr, int bitAdr, bool bitValue)
+        {
+            try
+            {
+                var dataToSend = BuildWriteBitPackage(dataType, db, startByteAdr, bitValue, bitAdr);
+                var s7data = RequestTsdu(dataToSend);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.WriteData, exc);
+            }
+        }
+
+        /// <summary>
+        /// Reads multiple vars in a single request.
+        /// You have to create and pass a list of DataItems and you obtain in response the same list with the values.
+        /// Values are stored in the property "Value" of the dataItem and are already converted.
+        /// If you don't want the conversion, just create a dataItem of bytes.
+        /// The number of DataItems as well as the total size of the requested data can not exceed a certain limit (protocol restriction).
+        /// </summary>
+        /// <param name="dataItems">List of dataitems that contains the list of variables that must be read.</param>
+        public void ReadMultipleVars(List<DataItem> dataItems)
+        {
+            AssertPduSizeForRead(dataItems);
+
+            try
+            {
+                // first create the header
+                int packageSize = 19 + (dataItems.Count * 12);
+                var dataToSend = new byte[packageSize];
+                var package = new MemoryStream(dataToSend);
+                WriteReadHeader(package, dataItems.Count);
+                // package.Add(0x02);  // datenart
+                foreach (var dataItem in dataItems)
+                {
+                    BuildReadDataRequestPackage(package, dataItem.DataType, dataItem.DB, dataItem.StartByteAdr, VarTypeToByteLength(dataItem.VarType, dataItem.Count));
+                }
+
+                byte[] s7data = RequestTsdu(dataToSend);
+
+                ValidateResponseCode((ReadWriteErrorCode)s7data[14]);
+
+                ParseDataIntoDataItems(s7data, dataItems);
+            }
+            catch (Exception exc)
+            {
+                throw new PlcException(ErrorCode.ReadData, exc);
+            }
+        }
+
+        /// <summary>
+        /// Read the PLC clock value.
+        /// </summary>
+        /// <returns>The current PLC time.</returns>
+        public System.DateTime ReadClock()
+        {
+            var request = BuildClockReadRequest();
+            var response = RequestTsdu(request);
+
+            return ParseClockReadResponse(response);
+        }
+
+        /// <summary>
+        /// Write the PLC clock value.
+        /// </summary>
+        /// <param name="value">The date and time to set the PLC clock to.</param>
+        public void WriteClock(System.DateTime value)
+        {
+            var request = BuildClockWriteRequest(value);
+            var response = RequestTsdu(request);
+
+            ParseClockWriteResponse(response);
+        }
+
+        /// <summary>
+        /// Read the current status from the PLC. A value of 0x08 indicates the PLC is in run status, regardless of the PLC type.
+        /// </summary>
+        /// <returns>The current PLC status.</returns>
+        public byte ReadStatus()
+        {
+            var dataToSend = BuildSzlReadRequestPackage(0x0424, 0);
+            var s7data = RequestTsdu(dataToSend);
+
+            return (byte) (s7data[37] & 0x0f);
+        }
+
+        private byte[] RequestTsdu(byte[] requestData) => RequestTsdu(requestData, 0, requestData.Length);
+
+        private byte[] RequestTsdu(byte[] requestData, int offset, int length)
+        {
+            return RequestTsduAsync(requestData, offset, length).GetAwaiter().GetResult();
+        }
+    }
+}

S7.Net/Properties/AssemblyInfo.cs

@@ -1,36 +1,3 @@
-using System.Reflection;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
 
-// Allgemeine Informationen über eine Assembly werden über die folgenden 
-// Attribute gesteuert. Ändern Sie diese Attributwerte, um die Informationen zu ändern,
-// die mit einer Assembly verknüpft sind.
-[assembly: AssemblyTitle("S7.Net")]
-[assembly: AssemblyDescription("")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("Microsoft")]
-[assembly: AssemblyProduct("S7.Net")]
-[assembly: AssemblyCopyright("Copyright © Microsoft 2009")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-
-// Durch Festlegen von ComVisible auf "false" werden die Typen in dieser Assembly unsichtbar 
-// für COM-Komponenten. Wenn Sie auf einen Typ in dieser Assembly von 
-// COM zugreifen müssen, legen Sie das ComVisible-Attribut für diesen Typ auf "true" fest.
-[assembly: ComVisible(false)]
-
-// Die folgende GUID bestimmt die ID der Typbibliothek, wenn dieses Projekt für COM verfügbar gemacht wird
-[assembly: Guid("1c01e753-a660-4c35-a681-c6f6a7deee83")]
-
-// Versionsinformationen für eine Assembly bestehen aus den folgenden vier Werten:
-//
-//      Hauptversion
-//      Nebenversion 
-//      Buildnummer
-//      Revision
-//
-// Sie können alle Werte angeben oder die standardmäßigen Build- und Revisionsnummern 
-// übernehmen, indem Sie "*" eingeben:
-// [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]
+[assembly: InternalsVisibleTo("S7.Net.UnitTest, PublicKey=00240000048000009400000006020000002400005253413100040000010001002d1032db55f60d64bf90ea1cc2247b5a8b9b6168a07bcd464a07ce2e425d027ff9409a64ba0e3f37718e14c50cf964d0d921e5ae8b8d74bd8a82431794f897cebf0ee668feb2ccd030153611b2808fcb7785c5e5136a98e0ec23de3c1ed385d2026c26e4bed5805ff9db7e0544f59b1f19d369d43403a624586795926e38c48d")]

S7.Net/Protocol/ConnectionRequest.cs

@@ -0,0 +1,28 @@
+namespace S7.Net.Protocol
+{
+    internal static class ConnectionRequest
+    {
+        public static byte[] GetCOTPConnectionRequest(TsapPair tsapPair)
+        {
+            byte[] bSend1 = {
+                    3, 0, 0, 22, //TPKT
+                    17,     //COTP Header Length
+                    224,    //Connect Request
+                    0, 0,   //Destination Reference
+                    0, 46,  //Source Reference
+                    0,      //Flags
+                    193,    //Parameter Code (src-tasp)
+                    2,      //Parameter Length
+                    tsapPair.Local.FirstByte, tsapPair.Local.SecondByte,   //Source TASP
+                    194,    //Parameter Code (dst-tasp)
+                    2,      //Parameter Length
+                    tsapPair.Remote.FirstByte, tsapPair.Remote.SecondByte,   //Destination TASP
+                    192,    //Parameter Code (tpdu-size)
+                    1,      //Parameter Length
+                    10      //TPDU Size (2^10 = 1024)
+                };
+
+            return bSend1;
+        }
+    }
+}

S7.Net/Protocol/ReadWriteErrorCode.cs

@@ -0,0 +1,15 @@
+
+namespace S7.Net.Protocol
+{
+    internal enum ReadWriteErrorCode : byte
+    {
+        Reserved = 0x00,
+        HardwareFault = 0x01,
+        AccessingObjectNotAllowed = 0x03,
+        AddressOutOfRange = 0x05,
+        DataTypeNotSupported = 0x06,
+        DataTypeInconsistent = 0x07,
+        ObjectDoesNotExist = 0x0a,
+        Success = 0xff
+    }
+}

S7.Net/Protocol/S7/DataItemAddress.cs

@@ -0,0 +1,37 @@
+namespace S7.Net.Protocol.S7
+{
+    /// <summary>
+    /// Represents an area of memory in the PLC
+    /// </summary>
+    internal class DataItemAddress
+    {
+        public DataItemAddress(DataType dataType, int db, int startByteAddress, int byteLength)
+        {
+            DataType = dataType;
+            DB = db;
+            StartByteAddress = startByteAddress;
+            ByteLength = byteLength;
+        }
+
+
+        /// <summary>
+        /// Memory area to read 
+        /// </summary>
+        public DataType DataType { get; }
+
+        /// <summary>
+        /// Address of memory area to read (example: for DB1 this value is 1, for T45 this value is 45)
+        /// </summary>
+        public int DB { get; }
+
+        /// <summary>
+        /// Address of the first byte to read
+        /// </summary>
+        public int StartByteAddress { get; }
+
+        /// <summary>
+        /// Length of data to read
+        /// </summary>
+        public int ByteLength { get; }
+    }
+}

S7.Net/Protocol/S7WriteMultiple.cs

@@ -0,0 +1,163 @@
+using System;
+using System.Collections.Generic;
+using S7.Net.Types;
+
+namespace S7.Net.Protocol
+{
+    internal static class S7WriteMultiple
+    {
+        public static int CreateRequest(ByteArray message, DataItem[] dataItems)
+        {
+            message.Add(Header.Template);
+
+            message[Header.Offsets.ParameterCount] = (byte) dataItems.Length;
+            var paramSize = dataItems.Length * Parameter.Template.Length;
+
+            Serialization.SetWordAt(message, Header.Offsets.ParameterSize,
+                (ushort) (2 + paramSize));
+
+            var paramOffset = Header.Template.Length;
+            var data = new ByteArray();
+
+            var itemCount = 0;
+
+            foreach (var item in dataItems)
+            {
+                itemCount++;
+                message.Add(Parameter.Template);
+                var value = Serialization.SerializeDataItem(item);
+                var wordLen = item.Value is bool ? 1 : 2;
+
+                message[paramOffset + Parameter.Offsets.WordLength] = (byte) wordLen;
+                Serialization.SetWordAt(message, paramOffset + Parameter.Offsets.Amount, (ushort) value.Length);
+                Serialization.SetWordAt(message, paramOffset + Parameter.Offsets.DbNumber, (ushort) item.DB);
+                message[paramOffset + Parameter.Offsets.Area] = (byte) item.DataType;
+
+                data.Add(0x00);
+                if (item.Value is bool b)
+                {
+                    if (item.BitAdr > 7)
+                        throw new ArgumentException(
+                            $"Cannot read bit with invalid {nameof(item.BitAdr)} '{item.BitAdr}'.", nameof(dataItems));
+
+                    Serialization.SetAddressAt(message, paramOffset + Parameter.Offsets.Address, item.StartByteAdr,
+                        item.BitAdr);
+
+                    data.Add(0x03);
+                    data.AddWord(1);
+
+                    data.Add(b ? (byte)1 : (byte)0);
+                    if (itemCount != dataItems.Length) { 
+                        data.Add(0);
+                    }
+                }
+                else
+                {
+                    Serialization.SetAddressAt(message, paramOffset + Parameter.Offsets.Address, item.StartByteAdr, 0);
+
+                    var len = value.Length;
+                    data.Add(0x04);
+                    data.AddWord((ushort) (len << 3));
+                    data.Add(value);
+                    
+                    if ((len & 0b1) == 1 && itemCount != dataItems.Length)
+                    {
+                        data.Add(0);
+                    }
+                }
+
+                paramOffset += Parameter.Template.Length;
+            }
+
+            message.Add(data.Array);
+
+            Serialization.SetWordAt(message, Header.Offsets.MessageLength, (ushort) message.Length);
+            Serialization.SetWordAt(message, Header.Offsets.DataLength, (ushort) (message.Length - paramOffset));
+
+            return message.Length;
+        }
+
+        public static void ParseResponse(byte[] message, int length, DataItem[] dataItems)
+        {
+            if (length < 12) throw new Exception("Not enough data received to parse write response.");
+
+            var messageError = Serialization.GetWordAt(message, 10);
+            if (messageError != 0)
+                throw new Exception($"Write failed with error {messageError}.");
+
+            if (length < 14 + dataItems.Length)
+                throw new Exception("Not enough data received to parse individual item responses.");
+
+            IList<byte> itemResults = new ArraySegment<byte>(message, 14, dataItems.Length);
+
+            List<Exception>? errors = null;
+
+            for (int i = 0; i < dataItems.Length; i++)
+            {
+                try
+                {
+                    Plc.ValidateResponseCode((ReadWriteErrorCode)itemResults[i]);
+                }
+                catch(Exception e)
+                {
+                    if (errors == null) errors = new List<Exception>();
+                    errors.Add(new Exception($"Write of dataItem {dataItems[i]} failed: {e.Message}."));
+                }
+
+            }
+
+            if (errors != null)
+                throw new AggregateException(
+                    $"Write failed for {errors.Count} items. See the innerExceptions for details.", errors);
+        }
+
+        private static class Header
+        {
+            public static byte[] Template { get; } =
+            {
+                0x03, 0x00, 0x00, 0x00, // TPKT
+                0x02, 0xf0, 0x80, // ISO DT
+                0x32, // S7 protocol ID
+                0x01, // JobRequest
+                0x00, 0x00, // Reserved
+                0x05, 0x00, // PDU reference
+                0x00, 0x0e, // Parameters length
+                0x00, 0x00, // Data length
+                0x05, // Function: Write var
+                0x00, // Number of items to write
+            };
+
+            public static class Offsets
+            {
+                public const int MessageLength = 2;
+                public const int ParameterSize = 13;
+                public const int DataLength = 15;
+                public const int ParameterCount = 18;
+            }
+        }
+
+        private static class Parameter
+        {
+            public static byte[] Template { get; } =
+            {
+                0x12, // Spec
+                0x0a, // Length of remaining bytes
+                0x10, // Addressing mode
+                0x02, // Transport size
+                0x00, 0x00, // Number of elements
+                0x00, 0x00, // DB number
+                0x84, // Area type
+                0x00, 0x00, 0x00 // Area offset
+            };
+
+            public static class Offsets
+            {
+                public const int WordLength = 3;
+                public const int Amount = 4;
+                public const int DbNumber = 6;
+                public const int Area = 8;
+                public const int Address = 9;
+            }
+        }
+    }
+}

S7.Net/Protocol/Serialization.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using S7.Net.Types;
+
+namespace S7.Net.Protocol
+{
+    internal static class Serialization
+    {
+        public static ushort GetWordAt(IList<byte> buf, int index)
+        {
+            return (ushort)((buf[index] << 8) + buf[index]);
+        }
+
+        public static byte[] SerializeDataItem(DataItem dataItem)
+        {
+            if (dataItem.Value == null)
+            {
+                throw new Exception($"DataItem.Value is null, cannot serialize. StartAddr={dataItem.StartByteAdr} VarType={dataItem.VarType}");
+            }
+
+            if (dataItem.Value is string s)
+                return dataItem.VarType switch
+                {
+                    VarType.S7String => S7String.ToByteArray(s, dataItem.Count),
+                    VarType.S7WString => S7WString.ToByteArray(s, dataItem.Count),
+                    _ => Types.String.ToByteArray(s, dataItem.Count)
+                };
+
+            if (dataItem.VarType == VarType.Date)
+            {
+                return Date.ToByteArray((System.DateTime)dataItem.Value);
+            }
+
+            return SerializeValue(dataItem.Value);
+        }
+
+        public static byte[] SerializeValue(object value)
+        {
+            switch (value.GetType().Name)
+            {
+                case "Boolean":
+                    return new[] { (byte)((bool)value ? 1 : 0) };
+                case "Byte":
+                    return Types.Byte.ToByteArray((byte)value);
+                case "Int16":
+                    return Types.Int.ToByteArray((Int16)value);
+                case "UInt16":
+                    return Types.Word.ToByteArray((UInt16)value);
+                case "Int32":
+                    return Types.DInt.ToByteArray((Int32)value);
+                case "UInt32":
+                    return Types.DWord.ToByteArray((UInt32)value);
+                case "Single":
+                    return Types.Real.ToByteArray((float)value);
+                case "Double":
+                    return Types.LReal.ToByteArray((double)value);
+                case "DateTime":
+                    return Types.DateTime.ToByteArray((System.DateTime)value);
+                case "Byte[]":
+                    return (byte[])value;
+                case "Int16[]":
+                    return Types.Int.ToByteArray((Int16[])value);
+                case "UInt16[]":
+                    return Types.Word.ToByteArray((UInt16[])value);
+                case "Int32[]":
+                    return Types.DInt.ToByteArray((Int32[])value);
+                case "UInt32[]":
+                    return Types.DWord.ToByteArray((UInt32[])value);
+                case "Single[]":
+                    return Types.Real.ToByteArray((float[])value);
+                case "Double[]":
+                    return Types.LReal.ToByteArray((double[])value);
+                case "String":
+                    // Hack: This is backwards compatible with the old code, but functionally it's broken
+                    // if the consumer does not pay attention to string length.
+                    var stringVal = (string)value;
+                    return Types.String.ToByteArray(stringVal, stringVal.Length);
+                case "DateTime[]":
+                    return Types.DateTime.ToByteArray((System.DateTime[])value);
+                case "DateTimeLong[]":
+                    return Types.DateTimeLong.ToByteArray((System.DateTime[])value);
+                default:
+                    throw new InvalidVariableTypeException();
+            }
+        }
+
+        public static void SetAddressAt(ByteArray buffer, int index, int startByte, byte bitNumber)
+        {
+            var start = startByte * 8 + bitNumber;
+            buffer[index + 2] = (byte)start;
+            start >>= 8;
+            buffer[index + 1] = (byte)start;
+            start >>= 8;
+            buffer[index] = (byte)start;
+        }
+
+        public static void SetWordAt(ByteArray buffer, int index, ushort value)
+        {
+            buffer[index] = (byte)(value >> 8);
+            buffer[index + 1] = (byte)value;
+        }
+    }
+}

S7.Net/Protocol/Tsap.cs

@@ -0,0 +1,31 @@
+namespace S7.Net.Protocol
+{
+    /// <summary>
+    /// Provides a representation of the Transport Service Access Point, or TSAP in short. TSAP's are used
+    /// to specify a client and server address. For most PLC types a default TSAP is available that allows
+    /// connection from any IP and can be calculated using the rack and slot numbers.
+    /// </summary>
+    public struct Tsap
+    {
+        /// <summary>
+        /// First byte of the TSAP.
+        /// </summary>
+        public byte FirstByte { get; set; }
+
+        /// <summary>
+        /// Second byte of the TSAP.
+        /// </summary>
+        public byte SecondByte { get; set; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Tsap" /> class using the specified values.
+        /// </summary>
+        /// <param name="firstByte">The first byte of the TSAP.</param>
+        /// <param name="secondByte">The second byte of the TSAP.</param>
+        public Tsap(byte firstByte, byte secondByte)
+        {
+            FirstByte = firstByte;
+            SecondByte = secondByte;
+        }
+    }
+}

S7.Net/Protocol/TsapPair.cs

@@ -0,0 +1,96 @@
+using System;
+
+namespace S7.Net.Protocol
+{
+    /// <summary>
+    /// Implements a pair of TSAP addresses used to connect to a PLC.
+    /// </summary>
+    public class TsapPair
+    {
+        /// <summary>
+        /// The local <see cref="Tsap" />.
+        /// </summary>
+        public Tsap Local { get; set; }
+
+        /// <summary>
+        /// The remote <see cref="Tsap" />
+        /// </summary>
+        public Tsap Remote { get; set; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TsapPair" /> class using the specified local and
+        /// remote TSAP.
+        /// </summary>
+        /// <param name="local">The local TSAP.</param>
+        /// <param name="remote">The remote TSAP.</param>
+        public TsapPair(Tsap local, Tsap remote)
+        {
+            Local = local;
+            Remote = remote;
+        }
+
+        /// <summary>
+        /// Builds a <see cref="TsapPair" /> that can be used to connect to a PLC using the default connection
+        /// addresses.
+        /// </summary>
+        /// <remarks>
+        /// The remote TSAP is constructed using <code>new Tsap(0x03, (byte) ((rack &lt;&lt; 5) | slot))</code>.
+        /// </remarks>
+        /// <param name="cpuType">The CPU type of the PLC.</param>
+        /// <param name="rack">The rack of the PLC's network card.</param>
+        /// <param name="slot">The slot of the PLC's network card.</param>
+        /// <returns>A TSAP pair that matches the given parameters.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">The <paramref name="cpuType"/> is invalid.
+        ///
+        /// -or-
+        ///
+        /// The <paramref name="rack"/> parameter is less than 0.
+        ///
+        /// -or-
+        ///
+        /// The <paramref name="rack"/> parameter is greater than 15.
+        ///
+        /// -or-
+        ///
+        /// The <paramref name="slot"/> parameter is less than 0.
+        ///
+        /// -or-
+        ///
+        /// The <paramref name="slot"/> parameter is greater than 15.</exception>
+        public static TsapPair GetDefaultTsapPair(CpuType cpuType, int rack, int slot)
+        {
+            if (rack < 0) throw InvalidRackOrSlot(rack, nameof(rack), "minimum", 0);
+            if (rack > 0x0F) throw InvalidRackOrSlot(rack, nameof(rack), "maximum", 0x0F);
+
+            if (slot < 0) throw InvalidRackOrSlot(slot, nameof(slot), "minimum", 0);
+            if (slot > 0x0F) throw InvalidRackOrSlot(slot, nameof(slot), "maximum", 0x0F);
+
+            switch (cpuType)
+            {
+                case CpuType.S7200:
+                    return new TsapPair(new Tsap(0x10, 0x00), new Tsap(0x10, 0x01));
+                case CpuType.Logo0BA8:
+                    // The actual values are probably on a per-project basis
+                    return new TsapPair(new Tsap(0x01, 0x00), new Tsap(0x01, 0x02));
+                case CpuType.S7200Smart:
+                case CpuType.S71200:
+                case CpuType.S71500:
+                case CpuType.S7300:
+                case CpuType.S7400:
+                    // Testing with S7 1500 shows only the remote TSAP needs to match. This might differ for other
+                    // PLC types.
+                    return new TsapPair(new Tsap(0x01, 0x00), new Tsap(0x03, (byte) ((rack << 5) | slot)));
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(cpuType), "Invalid CPU Type specified");
+            }
+        }
+
+        private static ArgumentOutOfRangeException InvalidRackOrSlot(int value, string name, string extrema,
+            int extremaValue)
+        {
+            return new ArgumentOutOfRangeException(name,
+                $"Invalid {name} value specified (decimal: {value}, hexadecimal: {value:X}), {extrema} value " +
+                $"is {extremaValue} (decimal) or {extremaValue:X} (hexadecimal).");
+        }
+    }
+}

S7.Net/S7.Net.csproj

@@ -1,122 +1,38 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProductVersion>9.0.30729</ProductVersion>
-    <SchemaVersion>2.0</SchemaVersion>
-    <ProjectGuid>{BFD484F9-3F04-42A2-BF2A-60A189A25DCF}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>S7.Net</RootNamespace>
-    <AssemblyName>S7.Net</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <FileUpgradeFlags>
-    </FileUpgradeFlags>
-    <UpgradeBackupLocation>
-    </UpgradeBackupLocation>
-    <OldToolsVersion>3.5</OldToolsVersion>
-    <PublishUrl>publish\</PublishUrl>
-    <Install>true</Install>
-    <InstallFrom>Disk</InstallFrom>
-    <UpdateEnabled>false</UpdateEnabled>
-    <UpdateMode>Foreground</UpdateMode>
-    <UpdateInterval>7</UpdateInterval>
-    <UpdateIntervalUnits>Days</UpdateIntervalUnits>
-    <UpdatePeriodically>false</UpdatePeriodically>
-    <UpdateRequired>false</UpdateRequired>
-    <MapFileExtensions>true</MapFileExtensions>
-    <ApplicationRevision>0</ApplicationRevision>
-    <ApplicationVersion>1.0.0.%2a</ApplicationVersion>
-    <IsWebBootstrapper>false</IsWebBootstrapper>
-    <UseApplicationTrust>false</UseApplicationTrust>
-    <BootstrapperEnabled>true</BootstrapperEnabled>
-    <TargetFrameworkProfile />
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <Prefer32Bit>false</Prefer32Bit>
-    <DocumentationFile>bin\Debug\S7.Net.xml</DocumentationFile>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <Prefer32Bit>false</Prefer32Bit>
-    <DocumentationFile>bin\Release\S7.Net.xml</DocumentationFile>
-  </PropertyGroup>
+<Project Sdk="Microsoft.NET.Sdk">
+  
   <PropertyGroup>
+    <TargetFrameworks>net452;net462;netstandard2.0;netstandard1.3;net5.0;net6.0;net7.0</TargetFrameworks>
     <SignAssembly>true</SignAssembly>
-  </PropertyGroup>
-  <PropertyGroup>
     <AssemblyOriginatorKeyFile>Properties\S7.Net.snk</AssemblyOriginatorKeyFile>
+    <InternalsVisibleTo>S7.Net.UnitTest</InternalsVisibleTo>
+
+    <PackageId>S7netplus</PackageId>
+    <Title>S7.Net Plus</Title>
+    <Description>A continuation of Juergen1969's Siemens communication library.</Description>
+    <Authors>Derek Heiser;Michele Cattafesta;Michael Croes;Raphael Schlameuß</Authors>
+    <PackageProjectUrl>https://github.com/killnine/s7netplus</PackageProjectUrl>
+    <RepositoryUrl>https://github.com/killnine/s7netplus</RepositoryUrl>
+    <RepositoryType>git</RepositoryType>
+    <PackageTags>PLC Siemens Communication S7</PackageTags>
+    <Copyright>Derek Heiser 2015</Copyright>
+    <LangVersion>latest</LangVersion>
+    <Nullable>Enable</Nullable>
+    <DebugType>portable</DebugType>
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <NoWarn>$(NoWarn);CS1591;NETSDK1138</NoWarn>
   </PropertyGroup>
-  <ItemGroup>
-    <Reference Include="System" />
-    <Reference Include="System.Core">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
-    <Reference Include="System.Xml.Linq">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
-    <Reference Include="System.Data.DataSetExtensions">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
-    <Reference Include="System.Data" />
-    <Reference Include="System.Xml" />
+
+  <PropertyGroup Condition="'$(TargetFramework)' == 'net452' Or '$(TargetFramework)' == 'net462' Or '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>NET_FULL</DefineConstants>
+  </PropertyGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' != 'net5.0' And '$(TargetFramework)' != 'net6.0' And '$(TargetFramework)' != 'net7.0'">
+    <PackageReference Include="System.Memory" Version="4.5.5" />
   </ItemGroup>
+  
   <ItemGroup>
-    <Compile Include="Conversion.cs" />
-    <Compile Include="Enums.cs" />
-    <Compile Include="PLC.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Types\Boolean.cs" />
-    <Compile Include="Types\Byte.cs" />
-    <Compile Include="Types\ByteArray.cs" />
-    <Compile Include="Types\Class.cs" />
-    <Compile Include="Types\Counter.cs" />
-    <Compile Include="Types\DataItem.cs" />
-    <Compile Include="Types\DInt.cs" />
-    <Compile Include="Types\Double.cs" />
-    <Compile Include="Types\DWord.cs" />
-    <Compile Include="Types\Int.cs" />
-    <Compile Include="Types\String.cs" />
-    <Compile Include="Types\Struct.cs" />
-    <Compile Include="Types\Timer.cs" />
-    <Compile Include="Types\Word.cs" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
   </ItemGroup>
-  <ItemGroup>
-    <BootstrapperPackage Include="Microsoft.Net.Client.3.5">
-      <Visible>False</Visible>
-      <ProductName>.NET Framework 3.5 SP1 Client Profile</ProductName>
-      <Install>false</Install>
-    </BootstrapperPackage>
-    <BootstrapperPackage Include="Microsoft.Net.Framework.3.5.SP1">
-      <Visible>False</Visible>
-      <ProductName>.NET Framework 3.5 SP1</ProductName>
-      <Install>true</Install>
-    </BootstrapperPackage>
-  </ItemGroup>
-  <ItemGroup>
-    <None Include="Properties\S7.Net.snk" />
-  </ItemGroup>
-  <ItemGroup />
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
-</Project>
+</Project>

S7.Net/StreamExtensions.cs

@@ -0,0 +1,58 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net
+{
+    /// <summary>
+    /// Extensions for Streams
+    /// </summary>
+    public static class StreamExtensions
+    {
+        /// <summary>
+        /// Reads bytes from the stream into the buffer until exactly the requested number of bytes (or EOF) have been read
+        /// </summary>
+        /// <param name="stream">the Stream to read from</param>
+        /// <param name="buffer">the buffer to read into</param>
+        /// <param name="offset">the offset in the buffer to read into</param>
+        /// <param name="count">the amount of bytes to read into the buffer</param>
+        /// <returns>returns the amount of read bytes</returns>
+        public static int ReadExact(this Stream stream, byte[] buffer, int offset, int count)
+        {
+            int read = 0;
+            int received;
+            do
+            {
+                received = stream.Read(buffer, offset + read, count - read);
+                read += received;
+            }
+            while (read < count && received > 0);
+
+            return read;
+        }
+
+        /// <summary>
+        /// Reads bytes from the stream into the buffer until exactly the requested number of bytes (or EOF) have been read
+        /// </summary>
+        /// <param name="stream">the Stream to read from</param>
+        /// <param name="buffer">the buffer to read into</param>
+        /// <param name="offset">the offset in the buffer to read into</param>
+        /// <param name="count">the amount of bytes to read into the buffer</param>
+        /// <param name="cancellationToken">A cancellation token that can be used to cancel the asynchronous operation.</param>
+        /// <returns>returns the amount of read bytes</returns>
+        public static async Task<int> ReadExactAsync(this Stream stream, byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+        {
+            int read = 0;
+            int received;
+            do
+            {
+                received = await stream.ReadAsync(buffer, offset + read, count - read, cancellationToken).ConfigureAwait(false);
+                read += received;
+            }
+            while (read < count && received > 0);
+
+            return read;
+        }
+    }
+}

S7.Net/TPKT.cs

@@ -0,0 +1,67 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace S7.Net
+{
+
+    /// <summary>
+    /// Describes a TPKT Packet
+    /// </summary>
+    internal class TPKT
+    {
+
+
+        public byte Version;
+        public byte Reserved1;
+        public int Length;
+        public byte[] Data;
+        private TPKT(byte version, byte reserved1, int length, byte[] data)
+        {
+            Version = version;
+            Reserved1 = reserved1;
+            Length = length;
+            Data = data;
+        }
+
+        /// <summary>
+        /// Reads a TPKT from the socket Async
+        /// </summary>
+        /// <param name="stream">The stream to read from</param>
+        /// <param name="cancellationToken">A cancellation token that can be used to cancel the asynchronous operation.</param>
+        /// <returns>Task TPKT Instace</returns>
+        public static async Task<TPKT> ReadAsync(Stream stream, CancellationToken cancellationToken)
+        {
+            var buf = new byte[4];
+            int len = await stream.ReadExactAsync(buf, 0, 4, cancellationToken).ConfigureAwait(false);
+            if (len < 4) throw new TPKTInvalidException("TPKT is incomplete / invalid");
+
+            var version = buf[0];
+            var reserved1 = buf[1];
+            var length = buf[2] * 256 + buf[3]; //BigEndian
+
+            var data = new byte[length - 4];
+            len = await stream.ReadExactAsync(data, 0, data.Length, cancellationToken).ConfigureAwait(false);
+            if (len < data.Length)
+                throw new TPKTInvalidException("TPKT payload incomplete / invalid");
+
+            return new TPKT
+            (
+                version: version,
+                reserved1: reserved1,
+                length: length,
+                data: data
+            );
+        }
+
+        public override string ToString()
+        {
+            return string.Format("Version: {0} Length: {1} Data: {2}",
+                Version,
+                Length,
+                BitConverter.ToString(Data)
+                );
+        }
+    }
+}

S7.Net/Types/Bit.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the conversion methods to convert Bit from S7 plc to C#.
+    /// </summary>
+    public static class Bit
+    {
+        /// <summary>
+        /// Converts a Bit to bool
+        /// </summary>
+        public static bool FromByte(byte v, byte bitAdr)
+        {
+            return (((int)v & (1 << bitAdr)) != 0);
+        }
+
+        /// <summary>
+        /// Converts an array of bytes to a BitArray.
+        /// </summary>
+        /// <param name="bytes">The bytes to convert.</param>
+        /// <returns>A BitArray with the same number of bits and equal values as <paramref name="bytes"/>.</returns>
+        public static BitArray ToBitArray(byte[] bytes) => ToBitArray(bytes, bytes.Length * 8);
+
+        /// <summary>
+        /// Converts an array of bytes to a BitArray.
+        /// </summary>
+        /// <param name="bytes">The bytes to convert.</param>
+        /// <param name="length">The number of bits to return.</param>
+        /// <returns>A BitArray with <paramref name="length"/> bits.</returns>
+        public static BitArray ToBitArray(byte[] bytes, int length)
+        {
+            if (length > bytes.Length * 8) throw new ArgumentException($"Not enough data in bytes to return {length} bits.", nameof(bytes));
+
+            var bitArr = new BitArray(bytes);
+            var bools = new bool[length];
+            for (var i = 0; i < length; i++) bools[i] = bitArr[i];
+
+            return new BitArray(bools);
+        }
+    }
+}

S7.Net/Types/Boolean.cs

@@ -1,6 +1,4 @@
-using System;
-
-namespace S7.Net.Types
+namespace S7.Net.Types
 {
     /// <summary>
     /// Contains the methods to read, set and reset bits inside bytes
@@ -12,27 +10,55 @@ namespace S7.Net.Types
         /// </summary>
         public static bool GetValue(byte value, int bit)
         {
-            if ((value & (int)Math.Pow(2, bit)) != 0)
-                return true;
-            else
-                return false;
+            return (((int)value & (1 << bit)) != 0);
         }
 
         /// <summary>
-        /// Sets the value of a bit to 1 (true), given the address of the bit
+        /// Sets the value of a bit to 1 (true), given the address of the bit. Returns
+        /// a copy of the value with the bit set.
         /// </summary>
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to set.</param>
+        /// <returns>The modified value with the bit at index set.</returns>
         public static byte SetBit(byte value, int bit)
         {
-            return (byte)(value | (byte)Math.Pow(2, bit));
+            SetBit(ref value, bit);
+
+            return value;
+        }
+
+        /// <summary>
+        /// Sets the value of a bit to 1 (true), given the address of the bit.
+        /// </summary>
+        /// <param name="value">The value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to set.</param>
+        public static void SetBit(ref byte value, int bit)
+        {
+            value = (byte) ((value | (1 << bit)) & 0xFF);
+        }
+
+        /// <summary>
+        /// Resets the value of a bit to 0 (false), given the address of the bit. Returns
+        /// a copy of the value with the bit cleared.
+        /// </summary>
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to clear.</param>
+        /// <returns>The modified value with the bit at index cleared.</returns>
+        public static byte ClearBit(byte value, int bit)
+        {
+            ClearBit(ref value, bit);
+
+            return value;
         }
 
         /// <summary>
         /// Resets the value of a bit to 0 (false), given the address of the bit
         /// </summary>
-        public static byte ClearBit(byte value, int bit)
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to clear.</param>
+        public static void ClearBit(ref byte value, int bit)
         {
-            return (byte)(value & (byte)(~(byte)Math.Pow(2, bit)));
+            value = (byte) (value & ~(1 << bit) & 0xFF);
         }
-
     }
 }

S7.Net/Types/Byte.cs

@@ -12,8 +12,7 @@ namespace S7.Net.Types
         /// </summary>
         public static byte[] ToByteArray(byte value)
         {
-            byte[] bytes = new byte[] { value};
-            return bytes;
+            return new byte[] { value }; ;
         }
        
         /// <summary>

S7.Net/Types/ByteArray.cs

@@ -6,11 +6,19 @@ namespace S7.Net.Types
     {
         List<byte> list = new List<byte>();
 
-        public byte[] array
+        public byte this[int index]
+        {
+            get => list[index];
+            set => list[index] = value;
+        }
+
+        public byte[] Array
         {
             get { return list.ToArray(); }
         }
 
+        public int Length => list.Count;
+
         public ByteArray()
         {
             list = new List<byte>();
@@ -31,14 +39,25 @@ namespace S7.Net.Types
             list.Add(item);
         }
 
+        public void AddWord(ushort value)
+        {
+            list.Add((byte) (value >> 8));
+            list.Add((byte) value);
+        }
+
         public void Add(byte[] items)
         {
             list.AddRange(items);
         }
 
+        public void Add(IEnumerable<byte> items)
+        {
+            list.AddRange(items);
+        }
+
         public void Add(ByteArray byteArray)
         {
-            list.AddRange(byteArray.array);
+            list.AddRange(byteArray.Array);
         }
     }
 }

S7.Net/Types/Class.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using System.Runtime.InteropServices;
 
 namespace S7.Net.Types
 {
@@ -13,8 +14,8 @@ namespace S7.Net.Types
         private static IEnumerable<PropertyInfo> GetAccessableProperties(Type classType)
         {
             return classType
-#if NETFX_CORE
-                .GetProperties().Where(p => p.GetSetMethod() != null);
+#if NETSTANDARD1_3
+                .GetTypeInfo().DeclaredProperties.Where(p => p.SetMethod != null);
 #else
                 .GetProperties(
                     BindingFlags.SetProperty |
@@ -25,10 +26,8 @@ namespace S7.Net.Types
 
         }
 
-        private static double GetIncreasedNumberOfBytes(double startingNumberOfBytes, Type type)
+        private static double GetIncreasedNumberOfBytes(double numBytes, Type type, PropertyInfo? propertyInfo)
         {
-            double numBytes = startingNumberOfBytes;
-
             switch (type.Name)
             {
                 case "Boolean":
@@ -40,28 +39,34 @@ namespace S7.Net.Types
                     break;
                 case "Int16":
                 case "UInt16":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                    IncrementToEven(ref numBytes);
                     numBytes += 2;
                     break;
                 case "Int32":
                 case "UInt32":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                    IncrementToEven(ref numBytes);
                     numBytes += 4;
                     break;
-                case "Float":
-                case "Double":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                case "Single":
+                    IncrementToEven(ref numBytes);
                     numBytes += 4;
                     break;
+                case "Double":
+                    IncrementToEven(ref numBytes);
+                    numBytes += 8;
+                    break;
+                case "String":
+                    S7StringAttribute? attribute = propertyInfo?.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                    if (attribute == default(S7StringAttribute))
+                        throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                    IncrementToEven(ref numBytes);
+                    numBytes += attribute.ReservedLengthInBytes;
+                    break;
                 default:
-                    var propertyClass = Activator.CreateInstance(type);
-                    numBytes += GetClassSize(propertyClass);
+                    var propertyClass = Activator.CreateInstance(type) ??
+                        throw new ArgumentException($"Failed to create instance of type {type}.", nameof(type));
+                    numBytes = GetClassSize(propertyClass, numBytes, true);
                     break;
             }
 
@@ -72,39 +77,49 @@ namespace S7.Net.Types
         /// Gets the size of the class in bytes.
         /// </summary>
         /// <param name="instance">An instance of the class</param>
+        /// <param name="numBytes">The offset of the current field.</param>
+        /// <param name="isInnerProperty"><see langword="true" /> if this property belongs to a class being serialized as member of the class requested for serialization; otherwise, <see langword="false" />.</param>
         /// <returns>the number of bytes</returns>
-        public static int GetClassSize(object instance)
+        public static double GetClassSize(object instance, double numBytes = 0.0, bool isInnerProperty = false)
         {
-            double numBytes = 0.0;
-
             var properties = GetAccessableProperties(instance.GetType());
             foreach (var property in properties)
             {
                 if (property.PropertyType.IsArray)
                 {
-                    Type elementType = property.PropertyType.GetElementType();
-                    Array array = (Array)property.GetValue(instance, null);
+                    Type elementType = property.PropertyType.GetElementType()!;
+                    Array array = (Array?) property.GetValue(instance, null) ??
+                        throw new ArgumentException($"Property {property.Name} on {instance} must have a non-null value to get it's size.", nameof(instance));
+
                     if (array.Length <= 0)
                     {
                         throw new Exception("Cannot determine size of class, because an array is defined which has no fixed size greater than zero.");
                     }
 
+                    IncrementToEven(ref numBytes);
                     for (int i = 0; i < array.Length; i++)
                     {
-                        numBytes = GetIncreasedNumberOfBytes(numBytes, elementType);
+                        numBytes = GetIncreasedNumberOfBytes(numBytes, elementType, property);
                     }
                 }
                 else
                 {
-                    numBytes = GetIncreasedNumberOfBytes(numBytes, property.PropertyType);
+                    numBytes = GetIncreasedNumberOfBytes(numBytes, property.PropertyType, property);
                 }
             }
-            return (int)numBytes;
+            if (false == isInnerProperty)
+            {
+                // enlarge numBytes to next even number because S7-Structs in a DB always will be resized to an even byte count
+                numBytes = Math.Ceiling(numBytes);
+                if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                    numBytes++;
+            }
+            return numBytes;
         }
 
-        private static object GetPropertyValue(Type propertyType, byte[] bytes, ref double numBytes)
+        private static object? GetPropertyValue(Type propertyType, PropertyInfo? propertyInfo, byte[] bytes, ref double numBytes)
         {
-            object value = null;
+            object? value = null;
 
             switch (propertyType.Name)
             {
@@ -124,52 +139,37 @@ namespace S7.Net.Types
                     numBytes++;
                     break;
                 case "Int16":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                    IncrementToEven(ref numBytes);
                     // hier auswerten
                     ushort source = Word.FromBytes(bytes[(int)numBytes + 1], bytes[(int)numBytes]);
                     value = source.ConvertToShort();
                     numBytes += 2;
                     break;
                 case "UInt16":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                    IncrementToEven(ref numBytes);
                     // hier auswerten
                     value = Word.FromBytes(bytes[(int)numBytes + 1], bytes[(int)numBytes]);
                     numBytes += 2;
                     break;
                 case "Int32":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
-                    // hier auswerten
-                    uint sourceUInt = DWord.FromBytes(bytes[(int)numBytes + 3],
-                                                                       bytes[(int)numBytes + 2],
-                                                                       bytes[(int)numBytes + 1],
-                                                                       bytes[(int)numBytes + 0]);
+                    IncrementToEven(ref numBytes);
+                    var wordBuffer = new byte[4];
+                    Array.Copy(bytes, (int)numBytes, wordBuffer, 0, wordBuffer.Length);
+                    uint sourceUInt = DWord.FromByteArray(wordBuffer);
                     value = sourceUInt.ConvertToInt();
                     numBytes += 4;
                     break;
                 case "UInt32":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
-                    // hier auswerten
-                    value = DWord.FromBytes(
-                        bytes[(int)numBytes],
-                        bytes[(int)numBytes + 1],
-                        bytes[(int)numBytes + 2],
-                        bytes[(int)numBytes + 3]);
+                    IncrementToEven(ref numBytes);
+                    var wordBuffer2 = new byte[4];
+                    Array.Copy(bytes, (int)numBytes, wordBuffer2, 0, wordBuffer2.Length);
+                    value = DWord.FromByteArray(wordBuffer2);
                     numBytes += 4;
                     break;
-                case "Double":
-                    numBytes = Math.Ceiling(numBytes);
-                    if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                        numBytes++;
+                case "Single":
+                    IncrementToEven(ref numBytes);
                     // hier auswerten
-                    value = Double.FromByteArray(
+                    value = Real.FromByteArray(
                         new byte[] {
                             bytes[(int)numBytes],
                             bytes[(int)numBytes + 1],
@@ -177,16 +177,38 @@ namespace S7.Net.Types
                             bytes[(int)numBytes + 3] });
                     numBytes += 4;
                     break;
-                default:
-                    var propClass = Activator.CreateInstance(propertyType);
-                    var buffer = new byte[GetClassSize(propClass)];
-                    if (buffer.Length > 0)
+                case "Double":
+                    IncrementToEven(ref numBytes);
+                    var buffer = new byte[8];
+                    Array.Copy(bytes, (int)numBytes, buffer, 0, 8);
+                    // hier auswerten
+                    value = LReal.FromByteArray(buffer);
+                    numBytes += 8;
+                    break;
+                case "String":
+                    S7StringAttribute? attribute = propertyInfo?.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                    if (attribute == default(S7StringAttribute))
+                        throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                    IncrementToEven(ref numBytes);
+
+                    // get the value
+                    var sData = new byte[attribute.ReservedLengthInBytes];
+                    Array.Copy(bytes, (int)numBytes, sData, 0, sData.Length);
+                    value = attribute.Type switch
                     {
-                        Buffer.BlockCopy(bytes, (int)Math.Ceiling(numBytes), buffer, 0, buffer.Length);
-                        FromBytes(propClass, buffer);
-                        value = propClass;
-                        numBytes += buffer.Length;
-                    }
+                        S7StringType.S7String => S7String.FromByteArray(sData),
+                        S7StringType.S7WString => S7WString.FromByteArray(sData),
+                        _ => throw new ArgumentException("Please use a valid string type for the S7StringAttribute")
+                    };
+                    numBytes += sData.Length;
+                    break;
+                default:
+                    var propClass = Activator.CreateInstance(propertyType) ??
+                        throw new ArgumentException($"Failed to create instance of type {propertyType}.", nameof(propertyType));
+
+                    numBytes = FromBytes(propClass, bytes, numBytes);
+                    value = propClass;
                     break;
             }
 
@@ -198,28 +220,27 @@ namespace S7.Net.Types
         /// </summary>
         /// <param name="sourceClass">The object to fill in the given array of bytes</param>
         /// <param name="bytes">The array of bytes</param>
-        public static void FromBytes(object sourceClass, byte[] bytes)
+        /// <param name="numBytes">The offset for the current field.</param>
+        /// <param name="isInnerClass"><see langword="true" /> if this class is the type of a member of the class to be serialized; otherwise, <see langword="false" />.</param>
+        public static double FromBytes(object sourceClass, byte[] bytes, double numBytes = 0, bool isInnerClass = false)
         {
             if (bytes == null)
-                return;
-
-            if (bytes.Length != GetClassSize(sourceClass))
-                return;
-
-            // and decode it
-            double numBytes = 0.0;
+                return numBytes;
 
             var properties = GetAccessableProperties(sourceClass.GetType());
             foreach (var property in properties)
             {
                 if (property.PropertyType.IsArray)
                 {
-                    Array array = (Array)property.GetValue(sourceClass, null);
-                    Type elementType = property.PropertyType.GetElementType();
+                    Array array = (Array?) property.GetValue(sourceClass, null) ??
+                        throw new ArgumentException($"Property {property.Name} on sourceClass must be an array instance.", nameof(sourceClass));
+
+                    IncrementToEven(ref numBytes);
+                    Type elementType = property.PropertyType.GetElementType()!;
                     for (int i = 0; i < array.Length && numBytes < bytes.Length; i++)
                     {
                         array.SetValue(
-                            GetPropertyValue(elementType, bytes, ref numBytes),
+                            GetPropertyValue(elementType, property, bytes, ref numBytes),
                             i);
                     }
                 }
@@ -227,17 +248,19 @@ namespace S7.Net.Types
                 {
                     property.SetValue(
                         sourceClass,
-                        GetPropertyValue(property.PropertyType, bytes, ref numBytes),
+                        GetPropertyValue(property.PropertyType, property, bytes, ref numBytes),
                         null);
                 }
             }
+
+            return numBytes;
         }
 
-        private static void ToBytes(object propertyValue, byte[] bytes, ref double numBytes)
+        private static double SetBytesFromProperty(object propertyValue, PropertyInfo? propertyInfo, byte[] bytes, double numBytes)
         {
             int bytePos = 0;
             int bitPos = 0;
-            byte[] bytes2 = null;
+            byte[]? bytes2 = null;
 
             switch (propertyValue.GetType().Name)
             {
@@ -269,56 +292,78 @@ namespace S7.Net.Types
                 case "UInt32":
                     bytes2 = DWord.ToByteArray((UInt32)propertyValue);
                     break;
+                case "Single":
+                    bytes2 = Real.ToByteArray((float)propertyValue);
+                    break;
                 case "Double":
-                    bytes2 = Double.ToByteArray((double)propertyValue);
+                    bytes2 = LReal.ToByteArray((double)propertyValue);
+                    break;
+                case "String":
+                    S7StringAttribute? attribute = propertyInfo?.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                    if (attribute == default(S7StringAttribute))
+                        throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                    bytes2 = attribute.Type switch
+                    {
+                        S7StringType.S7String => S7String.ToByteArray((string)propertyValue, attribute.ReservedLength),
+                        S7StringType.S7WString => S7WString.ToByteArray((string)propertyValue, attribute.ReservedLength),
+                        _ => throw new ArgumentException("Please use a valid string type for the S7StringAttribute")
+                    };
                     break;
                 default:
-                    bytes2 = ToBytes(propertyValue);
+                    numBytes = ToBytes(propertyValue, bytes, numBytes);
                     break;
             }
 
             if (bytes2 != null)
             {
-                // add them
-                numBytes = Math.Ceiling(numBytes);
-                if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
-                    numBytes++;
+                IncrementToEven(ref numBytes);
+
                 bytePos = (int)numBytes;
                 for (int bCnt = 0; bCnt < bytes2.Length; bCnt++)
                     bytes[bytePos + bCnt] = bytes2[bCnt];
                 numBytes += bytes2.Length;
             }
+
+            return numBytes;
         }
 
         /// <summary>
         /// Creates a byte array depending on the struct type.
         /// </summary>
-        /// <param name="sourceClass">The struct object</param>
+        /// <param name="sourceClass">The struct object.</param>
+        /// <param name="bytes">The target byte array.</param>
+        /// <param name="numBytes">The offset for the current field.</param>
         /// <returns>A byte array or null if fails.</returns>
-        public static byte[] ToBytes(object sourceClass)
+        public static double ToBytes(object sourceClass, byte[] bytes, double numBytes = 0.0)
         {
-            int size = GetClassSize(sourceClass);
-            byte[] bytes = new byte[size];
-            double numBytes = 0.0;
-
             var properties = GetAccessableProperties(sourceClass.GetType());
             foreach (var property in properties)
             {
+                var value = property.GetValue(sourceClass, null) ??
+                    throw new ArgumentException($"Property {property.Name} on sourceClass can't be null.", nameof(sourceClass));
+
                 if (property.PropertyType.IsArray)
                 {
-                    Array array = (Array)property.GetValue(sourceClass, null);
-                    Type elementType = property.PropertyType.GetElementType();
+                    Array array = (Array) value;
+                    IncrementToEven(ref numBytes);
                     for (int i = 0; i < array.Length && numBytes < bytes.Length; i++)
                     {
-                        ToBytes(array.GetValue(i), bytes, ref numBytes);
+                        numBytes = SetBytesFromProperty(array.GetValue(i)!, property, bytes, numBytes);
                     }
                 }
                 else
                 {
-                    ToBytes(property.GetValue(sourceClass, null), bytes, ref numBytes);
+                    numBytes = SetBytesFromProperty(value, property, bytes, numBytes);
                 }
             }
-            return bytes;
+            return numBytes;
+        }
+
+        private static void IncrementToEven(ref double numBytes)
+        {
+            numBytes = Math.Ceiling(numBytes);
+            if (numBytes % 2 > 0) numBytes++;
         }
     }
 }

S7.Net/Types/Counter.cs

@@ -18,16 +18,9 @@ namespace S7.Net.Types
             }
             // bytes[0] -> HighByte
             // bytes[1] -> LowByte
-            return FromBytes(bytes[1], bytes[0]);
+            return (UInt16)((bytes[0] << 8) | bytes[1]);
         }
 
-        /// <summary>
-        /// Converts a Counter (2 bytes) to ushort (UInt16)
-        /// </summary>
-        public static UInt16 FromBytes(byte LoVal, byte HiVal)
-        {
-            return (UInt16)(HiVal * 256 + LoVal);
-        }
 
         /// <summary>
         /// Converts a ushort (UInt16) to word (2 bytes)
@@ -35,16 +28,10 @@ namespace S7.Net.Types
         public static byte[] ToByteArray(UInt16 value)
         {
             byte[] bytes = new byte[2];
-            int x = 2;
-            long valLong = (long)((UInt16)value);
-            for (int cnt = 0; cnt < x; cnt++)
-            {
-                Int64 x1 = (Int64)Math.Pow(256, (cnt));
 
-                Int64 x3 = (Int64)(valLong / x1);
-                bytes[x - cnt - 1] = (byte)(x3 & 255);
-                valLong -= bytes[x - cnt - 1] * x1;
-            }
+            bytes[0] = (byte)((value << 8) & 0xFF);
+            bytes[1] = (byte)((value) & 0xFF);
+            
             return bytes;
         }
 
@@ -56,7 +43,7 @@ namespace S7.Net.Types
             ByteArray arr = new ByteArray();
             foreach (UInt16 val in value)
                 arr.Add(ToByteArray(val));
-            return arr.array;
+            return arr.Array;
         }
 
         /// <summary>

S7.Net/Types/DInt.cs

@@ -16,16 +16,9 @@ namespace S7.Net.Types
             {
                 throw new ArgumentException("Wrong number of bytes. Bytes array must contain 4 bytes.");
             }
-            return FromBytes(bytes[3], bytes[2], bytes[1], bytes[0]);
+            return bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3];
         }
 
-        /// <summary>
-        /// Converts a S7 DInt (4 bytes) to int (Int32)
-        /// </summary>
-        public static Int32 FromBytes(byte v1, byte v2, byte v3, byte v4)
-        {
-            return (Int32)(v1 + v2 * Math.Pow(2, 8) + v3 * Math.Pow(2, 16) + v4 * Math.Pow(2, 24));
-        }
 
         /// <summary>
         /// Converts a int (Int32) to S7 DInt (4 bytes)
@@ -33,16 +26,12 @@ namespace S7.Net.Types
         public static byte[] ToByteArray(Int32 value)
         {
             byte[] bytes = new byte[4];
-            int x = 4;
-            long valLong = (long)((Int32)value);
-            for (int cnt = 0; cnt < x; cnt++)
-            {
-                Int64 x1 = (Int64)Math.Pow(256, (cnt));
 
-                Int64 x3 = (Int64)(valLong / x1);
-                bytes[x - cnt - 1] = (byte)(x3 & 255);
-                valLong -= bytes[x - cnt - 1] * x1;
-            }
+            bytes[0] = (byte)((value >> 24) & 0xFF);
+            bytes[1] = (byte)((value >> 16) & 0xFF);
+            bytes[2] = (byte)((value >> 8) & 0xFF);
+            bytes[3] = (byte)((value) & 0xFF);
+
             return bytes;
         }
 
@@ -54,7 +43,7 @@ namespace S7.Net.Types
             ByteArray arr = new ByteArray();
             foreach (Int32 val in value)
                 arr.Add(ToByteArray(val));
-            return arr.array;
+            return arr.Array;
         }
 
         /// <summary>
@@ -71,18 +60,6 @@ namespace S7.Net.Types
             return values;
         }
         
-        /// <summary>
-        /// Converts from C# long (Int64) to C# int (Int32)
-        /// </summary>
-        public static Int32 CDWord(Int64 value)
-        {
-            if (value > Int32.MaxValue)
-            {
-                value -= (long)Int32.MaxValue + 1;
-                value = (long)Int32.MaxValue + 1 - value;
-                value *= -1;
-            }
-            return (int)value;
-        }
+
     }
 }

S7.Net/Types/DWord.cs

@@ -12,36 +12,39 @@ namespace S7.Net.Types
         /// </summary>
         public static UInt32 FromByteArray(byte[] bytes)
         {
-            return FromBytes(bytes[3], bytes[2], bytes[1], bytes[0]);
+            return (UInt32)(bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3]);
         }
 
+
         /// <summary>
-        /// Converts a S7 DWord (4 bytes) to uint (UInt32)
+        /// Converts 4 bytes to DWord (UInt32)
         /// </summary>
-        public static UInt32 FromBytes(byte v1, byte v2, byte v3, byte v4)
+        public static UInt32 FromBytes(byte b1, byte b2, byte b3, byte b4)
         {
-            return (UInt32)(v1 + v2 * Math.Pow(2, 8) + v3 * Math.Pow(2, 16) + v4 * Math.Pow(2, 24));
+            return (UInt32)((b4 << 24) | (b3 << 16) | (b2 << 8) | b1);
         }
 
+
         /// <summary>
         /// Converts a uint (UInt32) to S7 DWord (4 bytes) 
         /// </summary>
         public static byte[] ToByteArray(UInt32 value)
         {
             byte[] bytes = new byte[4];
-            int x = 4;
-            long valLong = (long)((UInt32)value);
-            for (int cnt = 0; cnt < x; cnt++)
-            {
-                Int64 x1 = (Int64)Math.Pow(256, (cnt));
 
-                Int64 x3 = (Int64)(valLong / x1);
-                bytes[x - cnt - 1] = (byte)(x3 & 255);
-                valLong -= bytes[x - cnt - 1] * x1;
-            }
+            bytes[0] = (byte)((value >> 24) & 0xFF);
+            bytes[1] = (byte)((value >> 16) & 0xFF);
+            bytes[2] = (byte)((value >> 8) & 0xFF);
+            bytes[3] = (byte)((value) & 0xFF);
+
             return bytes;
         }
 
+
+
+
+
+
         /// <summary>
         /// Converts an array of uint (UInt32) to an array of S7 DWord (4 bytes) 
         /// </summary>
@@ -50,7 +53,7 @@ namespace S7.Net.Types
             ByteArray arr = new ByteArray();
             foreach (UInt32 val in value)
                 arr.Add(ToByteArray(val));
-            return arr.array;
+            return arr.Array;
         }
 
         /// <summary>

S7.Net/Types/DataItem.cs

@@ -1,4 +1,7 @@
-namespace S7.Net.Types
+using S7.Net.Protocol.S7;
+using System;
+
+namespace S7.Net.Types
 {
     /// <summary>
     /// Create an instance of a memory block that can be read by using ReadMultipleVars
@@ -25,6 +28,11 @@
         /// </summary>
         public int StartByteAdr { get; set; }
 
+        /// <summary>
+        /// Addess of bit to read from StartByteAdr
+        /// </summary>
+        public byte BitAdr { get; set; }
+
         /// <summary>
         /// Number of variables to read
         /// </summary>
@@ -33,7 +41,7 @@
         /// <summary>
         /// Contains the value of the memory area after the read has been executed
         /// </summary>
-        public object Value { get; set; }
+        public object? Value { get; set; }
 
         /// <summary>
         /// Create an instance of DataItem
@@ -43,5 +51,54 @@
             VarType = VarType.Byte;
             Count = 1;
         }
+
+        /// <summary>
+        /// Create an instance of <see cref="DataItem"/> from the supplied address.
+        /// </summary>
+        /// <param name="address">The address to create the DataItem for.</param>
+        /// <returns>A new <see cref="DataItem"/> instance with properties parsed from <paramref name="address"/>.</returns>
+        /// <remarks>The <see cref="Count" /> property is not parsed from the address.</remarks>
+        public static DataItem FromAddress(string address)
+        {
+            PLCAddress.Parse(address, out var dataType, out var dbNumber, out var varType, out var startByte,
+                out var bitNumber);
+
+            return new DataItem
+            {
+                DataType = dataType,
+                DB = dbNumber,
+                VarType = varType,
+                StartByteAdr = startByte,
+                BitAdr = (byte) (bitNumber == -1 ? 0 : bitNumber)
+            };
+        }
+
+        /// <summary>
+        /// Create an instance of <see cref="DataItem"/> from the supplied address and value.
+        /// </summary>
+        /// <param name="address">The address to create the DataItem for.</param>
+        /// <param name="value">The value to be applied to the DataItem.</param>
+        /// <returns>A new <see cref="DataItem"/> instance with properties parsed from <paramref name="address"/> and the supplied value set.</returns>
+        public static DataItem FromAddressAndValue<T>(string address, T value)
+        {
+            var dataItem = FromAddress(address);
+            dataItem.Value = value;
+
+            if (typeof(T).IsArray)
+            {
+                var array = ((Array?)dataItem.Value);
+                if ( array != null)
+                {
+                    dataItem.Count = array.Length;
+                }
+            }
+
+            return dataItem;
+        }
+
+        internal static DataItemAddress GetDataItemAddress(DataItem dataItem)
+        {
+            return new DataItemAddress(dataItem.DataType, dataItem.DB, dataItem.StartByteAdr, Plc.VarTypeToByteLength(dataItem.VarType, dataItem.Count));
+        }
     }
 }

S7.Net/Types/Date.cs

@@ -0,0 +1,82 @@
+using System;
+using S7.Net.Helper;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the conversion methods to convert Words from S7 plc to C#.
+    /// </summary>
+    public static class Date
+    {
+        /// <summary>
+        /// Minimum allowed date for the IEC date type
+        /// </summary>
+        public static System.DateTime IecMinDate { get; } = new(year: 1990, month: 01, day: 01);
+        
+        /// <summary>
+        /// Maximum allowed date for the IEC date type
+        /// <remarks>
+        /// Although the spec allows only a max date of 31-12-2168, the PLC IEC date goes up to 06-06-2169 (which is the actual
+        /// WORD max value - 65535) 
+        /// </remarks>
+        /// </summary>
+        public static System.DateTime IecMaxDate { get; } = new(year: 2169, month: 06, day: 06);
+        
+        private static readonly ushort MaxNumberOfDays = (ushort)(IecMaxDate - IecMinDate).TotalDays;
+        
+        /// <summary>
+        /// Converts a word (2 bytes) to IEC date (<see cref="System.DateTime"/>)
+        /// </summary>
+        public static System.DateTime FromByteArray(byte[] bytes)
+        {
+            if (bytes.Length != 2)
+            {
+                throw new ArgumentException("Wrong number of bytes. Bytes array must contain 2 bytes.");
+            }
+
+            var daysSinceDateStart = Word.FromByteArray(bytes);
+            if (daysSinceDateStart > MaxNumberOfDays)
+            {
+                throw new ArgumentException($"Read number exceeded the number of maximum days in the IEC date (read: {daysSinceDateStart}, max: {MaxNumberOfDays})", 
+                    nameof(bytes));
+            }
+            
+            return IecMinDate.AddDays(daysSinceDateStart);
+        }
+
+        /// <summary>
+        /// Converts a <see cref="System.DateTime"/> to word (2 bytes)
+        /// </summary>
+        public static byte[] ToByteArray(System.DateTime dateTime) => Word.ToByteArray(dateTime.GetDaysSinceIecDateStart());
+
+        /// <summary>
+        /// Converts an array of <see cref="System.DateTime"/>s to an array of bytes
+        /// </summary>
+        public static byte[] ToByteArray(System.DateTime[] value)
+        {
+            var arr = new ByteArray();
+            foreach (var date in value)
+                arr.Add(ToByteArray(date));
+            return arr.Array;
+        }
+
+        /// <summary>
+        /// Converts an array of bytes to an array of <see cref="System.DateTime"/>s
+        /// </summary>
+        public static System.DateTime[] ToArray(byte[] bytes)
+        {
+            var values = new System.DateTime[bytes.Length / sizeof(ushort)];
+
+            for (int i = 0; i < values.Length; i++)
+            {
+                values[i] = FromByteArray(
+                    new[]
+                    {
+                        bytes[i], bytes[i + 1]
+                    });
+            }
+
+            return values;
+        }
+    }
+}

S7.Net/Types/DateTime.cs

@@ -0,0 +1,156 @@
+using System;
+using System.Collections.Generic;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the methods to convert between <see cref="T:System.DateTime"/> and S7 representation of datetime values.
+    /// </summary>
+    public static class DateTime
+    {
+        /// <summary>
+        /// The minimum <see cref="T:System.DateTime"/> value supported by the specification.
+        /// </summary>
+        public static readonly System.DateTime SpecMinimumDateTime = new System.DateTime(1990, 1, 1);
+
+        /// <summary>
+        /// The maximum <see cref="T:System.DateTime"/> value supported by the specification.
+        /// </summary>
+        public static readonly System.DateTime SpecMaximumDateTime = new System.DateTime(2089, 12, 31, 23, 59, 59, 999);
+
+        /// <summary>
+        /// Parses a <see cref="T:System.DateTime"/> value from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>A <see cref="T:System.DateTime"/> object representing the value read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the length of
+        ///   <paramref name="bytes"/> is not 8 or any value in <paramref name="bytes"/>
+        ///   is outside the valid range of values.</exception>
+        public static System.DateTime FromByteArray(byte[] bytes)
+        {
+            return FromByteArrayImpl(bytes);
+        }
+
+        /// <summary>
+        /// Parses an array of <see cref="T:System.DateTime"/> values from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>An array of <see cref="T:System.DateTime"/> objects representing the values read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the length of
+        ///   <paramref name="bytes"/> is not a multiple of 8 or any value in
+        ///   <paramref name="bytes"/> is outside the valid range of values.</exception>
+        public static System.DateTime[] ToArray(byte[] bytes)
+        {
+            if (bytes.Length % 8 != 0)
+                throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Length,
+                    $"Parsing an array of DateTime requires a multiple of 8 bytes of input data, input data is '{bytes.Length}' long.");
+
+            var cnt = bytes.Length / 8;
+            var result = new System.DateTime[bytes.Length / 8];
+
+            for (var i = 0; i < cnt; i++)
+                result[i] = FromByteArrayImpl(new ArraySegment<byte>(bytes, i * 8, 8));
+
+            return result;
+        }
+
+        private static System.DateTime FromByteArrayImpl(IList<byte> bytes)
+        {
+            if (bytes.Count != 8)
+                throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Count,
+                    $"Parsing a DateTime requires exactly 8 bytes of input data, input data is {bytes.Count} bytes long.");
+
+            int DecodeBcd(byte input) => 10 * (input >> 4) + (input & 0b00001111);
+
+            int ByteToYear(byte bcdYear)
+            {
+                var input = DecodeBcd(bcdYear);
+                if (input < 90) return input + 2000;
+                if (input < 100) return input + 1900;
+
+                throw new ArgumentOutOfRangeException(nameof(bcdYear), bcdYear,
+                    $"Value '{input}' is higher than the maximum '99' of S7 date and time representation.");
+            }
+
+            int AssertRangeInclusive(int input, byte min, byte max, string field)
+            {
+                if (input < min)
+                    throw new ArgumentOutOfRangeException(nameof(input), input,
+                        $"Value '{input}' is lower than the minimum '{min}' allowed for {field}.");
+                if (input > max)
+                    throw new ArgumentOutOfRangeException(nameof(input), input,
+                        $"Value '{input}' is higher than the maximum '{max}' allowed for {field}.");
+
+                return input;
+            }
+
+            var year = ByteToYear(bytes[0]);
+            var month = AssertRangeInclusive(DecodeBcd(bytes[1]), 1, 12, "month");
+            var day = AssertRangeInclusive(DecodeBcd(bytes[2]), 1, 31, "day of month");
+            var hour = AssertRangeInclusive(DecodeBcd(bytes[3]), 0, 23, "hour");
+            var minute = AssertRangeInclusive(DecodeBcd(bytes[4]), 0, 59, "minute");
+            var second = AssertRangeInclusive(DecodeBcd(bytes[5]), 0, 59, "second");
+            var hsec = AssertRangeInclusive(DecodeBcd(bytes[6]), 0, 99, "first two millisecond digits");
+            var msec = AssertRangeInclusive(bytes[7] >> 4, 0, 9, "third millisecond digit");
+            var dayOfWeek = AssertRangeInclusive(bytes[7] & 0b00001111, 1, 7, "day of week");
+
+            return new System.DateTime(year, month, day, hour, minute, second, hsec * 10 + msec);
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:System.DateTime"/> value to a byte array.
+        /// </summary>
+        /// <param name="dateTime">The DateTime value to convert.</param>
+        /// <returns>A byte array containing the S7 date time representation of <paramref name="dateTime"/>.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the value of
+        ///   <paramref name="dateTime"/> is before <see cref="P:SpecMinimumDateTime"/>
+        ///   or after <see cref="P:SpecMaximumDateTime"/>.</exception>
+        public static byte[] ToByteArray(System.DateTime dateTime)
+        {
+            byte EncodeBcd(int value)
+            {
+                return (byte) ((value / 10 << 4) | value % 10);
+            }
+
+            if (dateTime < SpecMinimumDateTime)
+                throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime,
+                    $"Date time '{dateTime}' is before the minimum '{SpecMinimumDateTime}' supported in S7 date time representation.");
+
+            if (dateTime > SpecMaximumDateTime)
+                throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime,
+                    $"Date time '{dateTime}' is after the maximum '{SpecMaximumDateTime}' supported in S7 date time representation.");
+
+            byte MapYear(int year) => (byte) (year < 2000 ? year - 1900 : year - 2000);
+
+            int DayOfWeekToInt(DayOfWeek dayOfWeek) => (int) dayOfWeek + 1;
+
+            return new[]
+            {
+                EncodeBcd(MapYear(dateTime.Year)),
+                EncodeBcd(dateTime.Month),
+                EncodeBcd(dateTime.Day),
+                EncodeBcd(dateTime.Hour),
+                EncodeBcd(dateTime.Minute),
+                EncodeBcd(dateTime.Second),
+                EncodeBcd(dateTime.Millisecond / 10),
+                (byte) (dateTime.Millisecond % 10 << 4 | DayOfWeekToInt(dateTime.DayOfWeek))
+            };
+        }
+
+        /// <summary>
+        /// Converts an array of <see cref="T:System.DateTime"/> values to a byte array.
+        /// </summary>
+        /// <param name="dateTimes">The DateTime values to convert.</param>
+        /// <returns>A byte array containing the S7 date time representations of <paramref name="dateTimes"/>.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when any value of
+        ///   <paramref name="dateTimes"/> is before <see cref="P:SpecMinimumDateTime"/>
+        ///   or after <see cref="P:SpecMaximumDateTime"/>.</exception>
+        public static byte[] ToByteArray(System.DateTime[] dateTimes)
+        {
+            var bytes = new List<byte>(dateTimes.Length * 8);
+            foreach (var dateTime in dateTimes) bytes.AddRange(ToByteArray(dateTime));
+
+            return bytes.ToArray();
+        }
+    }
+}

S7.Net/Types/DateTimeLong.cs

@@ -0,0 +1,185 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the methods to convert between <see cref="T:System.DateTime" /> and S7 representation of DateTimeLong (DTL) values.
+    /// </summary>
+    public static class DateTimeLong
+    {
+        public const int TypeLengthInBytes = 12;
+        /// <summary>
+        /// The minimum <see cref="T:System.DateTime" /> value supported by the specification.
+        /// </summary>
+        public static readonly System.DateTime SpecMinimumDateTime = new System.DateTime(1970, 1, 1);
+
+        /// <summary>
+        /// The maximum <see cref="T:System.DateTime" /> value supported by the specification.
+        /// </summary>
+        public static readonly System.DateTime SpecMaximumDateTime = new System.DateTime(2262, 4, 11, 23, 47, 16, 854);
+
+        /// <summary>
+        /// Parses a <see cref="T:System.DateTime" /> value from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>A <see cref="T:System.DateTime" /> object representing the value read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when the length of
+        /// <paramref name="bytes" /> is not 12 or any value in <paramref name="bytes" />
+        /// is outside the valid range of values.
+        /// </exception>
+        public static System.DateTime FromByteArray(byte[] bytes)
+        {
+            return FromByteArrayImpl(bytes);
+        }
+
+        /// <summary>
+        /// Parses an array of <see cref="T:System.DateTime" /> values from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>An array of <see cref="T:System.DateTime" /> objects representing the values read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when the length of
+        /// <paramref name="bytes" /> is not a multiple of 12 or any value in
+        /// <paramref name="bytes" /> is outside the valid range of values.
+        /// </exception>
+        public static System.DateTime[] ToArray(byte[] bytes)
+        {
+            if (bytes.Length % TypeLengthInBytes != 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Length,
+                    $"Parsing an array of DateTimeLong requires a multiple of 12 bytes of input data, input data is '{bytes.Length}' long.");
+            }
+
+            var cnt = bytes.Length / TypeLengthInBytes;
+            var result = new System.DateTime[cnt];
+
+            for (var i = 0; i < cnt; i++)
+            {
+                var slice = new byte[TypeLengthInBytes];
+                Array.Copy(bytes, i * TypeLengthInBytes, slice, 0, TypeLengthInBytes);
+                result[i] = FromByteArrayImpl(slice);
+            }
+
+            return result;
+        }
+
+        private static System.DateTime FromByteArrayImpl(byte[] bytes)
+        {
+            if (bytes.Length != TypeLengthInBytes)
+            {
+                throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Length,
+                    $"Parsing a DateTimeLong requires exactly 12 bytes of input data, input data is {bytes.Length} bytes long.");
+            }
+
+
+            var year = AssertRangeInclusive(Word.FromBytes(bytes[1], bytes[0]), 1970, 2262, "year");
+            var month = AssertRangeInclusive(bytes[2], 1, 12, "month");
+            var day = AssertRangeInclusive(bytes[3], 1, 31, "day of month");
+            var dayOfWeek = AssertRangeInclusive(bytes[4], 1, 7, "day of week");
+            var hour = AssertRangeInclusive(bytes[5], 0, 23, "hour");
+            var minute = AssertRangeInclusive(bytes[6], 0, 59, "minute");
+            var second = AssertRangeInclusive(bytes[7], 0, 59, "second");
+            ;
+
+            var nanoseconds = AssertRangeInclusive<uint>(DWord.FromBytes(bytes[11], bytes[10], bytes[9], bytes[8]), 0,
+                999999999, "nanoseconds");
+
+            var time = new System.DateTime(year, month, day, hour, minute, second);
+            return time.AddTicks(nanoseconds / 100);
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:System.DateTime" /> value to a byte array.
+        /// </summary>
+        /// <param name="dateTime">The DateTime value to convert.</param>
+        /// <returns>A byte array containing the S7 DateTimeLong representation of <paramref name="dateTime" />.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when the value of
+        /// <paramref name="dateTime" /> is before <see cref="P:SpecMinimumDateTime" />
+        /// or after <see cref="P:SpecMaximumDateTime" />.
+        /// </exception>
+        public static byte[] ToByteArray(System.DateTime dateTime)
+        {
+            if (dateTime < SpecMinimumDateTime)
+            {
+                throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime,
+                    $"Date time '{dateTime}' is before the minimum '{SpecMinimumDateTime}' supported in S7 DateTimeLong representation.");
+            }
+
+            if (dateTime > SpecMaximumDateTime)
+            {
+                throw new ArgumentOutOfRangeException(nameof(dateTime), dateTime,
+                    $"Date time '{dateTime}' is after the maximum '{SpecMaximumDateTime}' supported in S7 DateTimeLong representation.");
+            }
+
+            var stream = new MemoryStream(TypeLengthInBytes);
+            // Convert Year
+            stream.Write(Word.ToByteArray(Convert.ToUInt16(dateTime.Year)), 0, 2);
+
+            // Convert Month
+            stream.WriteByte(Convert.ToByte(dateTime.Month));
+
+            // Convert Day
+            stream.WriteByte(Convert.ToByte(dateTime.Day));
+
+            // Convert WeekDay. NET DateTime starts with Sunday = 0, while S7DT has Sunday = 1.
+            stream.WriteByte(Convert.ToByte(dateTime.DayOfWeek + 1));
+
+            // Convert Hour
+            stream.WriteByte(Convert.ToByte(dateTime.Hour));
+
+            // Convert Minutes
+            stream.WriteByte(Convert.ToByte(dateTime.Minute));
+
+            // Convert Seconds
+            stream.WriteByte(Convert.ToByte(dateTime.Second));
+
+            // Convert Nanoseconds. Net DateTime has a representation of 1 Tick = 100ns.
+            // Thus First take the ticks Mod 1 Second (1s = 10'000'000 ticks), and then Convert to nanoseconds.
+            stream.Write(DWord.ToByteArray(Convert.ToUInt32(dateTime.Ticks % 10000000 * 100)), 0, 4);
+
+            return stream.ToArray();
+        }
+
+        /// <summary>
+        /// Converts an array of <see cref="T:System.DateTime" /> values to a byte array.
+        /// </summary>
+        /// <param name="dateTimes">The DateTime values to convert.</param>
+        /// <returns>A byte array containing the S7 DateTimeLong representations of <paramref name="dateTimes" />.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">
+        /// Thrown when any value of
+        /// <paramref name="dateTimes" /> is before <see cref="P:SpecMinimumDateTime" />
+        /// or after <see cref="P:SpecMaximumDateTime" />.
+        /// </exception>
+        public static byte[] ToByteArray(System.DateTime[] dateTimes)
+        {
+            var bytes = new List<byte>(dateTimes.Length * TypeLengthInBytes);
+            foreach (var dateTime in dateTimes)
+            {
+                bytes.AddRange(ToByteArray(dateTime));
+            }
+
+            return bytes.ToArray();
+        }
+
+        private static T AssertRangeInclusive<T>(T input, T min, T max, string field) where T : IComparable<T>
+        {
+            if (input.CompareTo(min) < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(input), input,
+                    $"Value '{input}' is lower than the minimum '{min}' allowed for {field}.");
+            }
+
+            if (input.CompareTo(max) > 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(input), input,
+                    $"Value '{input}' is higher than the maximum '{max}' allowed for {field}.");
+            }
+
+            return input;
+        }
+    }
+}

S7.Net/Types/Double.cs

@@ -5,50 +5,13 @@ namespace S7.Net.Types
     /// <summary>
     /// Contains the conversion methods to convert Real from S7 plc to C# double.
     /// </summary>
+    [Obsolete("Class Double is obsolete. Use Real instead for 32bit floating point, or LReal for 64bit floating point.")]
     public static class Double
     {
         /// <summary>
         /// Converts a S7 Real (4 bytes) to double
         /// </summary>
-        public static double FromByteArray(byte[] bytes)
-        {
-            if (bytes.Length != 4)
-            {
-                throw new ArgumentException("Wrong number of bytes. Bytes array must contain 4 bytes.");
-            }
-            byte v1 = bytes[0];
-            byte v2 = bytes[1];
-            byte v3 = bytes[2];
-            byte v4 = bytes[3];
-
-            if ((int)v1 + v2 + v3 + v4 == 0)
-            {
-                return 0.0;
-            }
-            else
-            {
-                // nun String bilden
-                string txt = ValToBinString(v1) + ValToBinString(v2) + ValToBinString(v3) + ValToBinString(v4);
-                // erstmal das Vorzeichen
-                int vz = int.Parse(txt.Substring(0, 1));
-                int exd = Conversion.BinStringToInt32(txt.Substring(1, 8));
-                string ma = txt.Substring(9, 23);
-                double mantisse = 1;
-                double faktor = 1.0;
-
-                //das ist die Anzahl der restlichen bit's
-                for (int cnt = 0; cnt <= 22; cnt++)
-                {
-                    faktor = faktor / 2.0;
-                    //entspricht 2^-y
-                    if (ma.Substring(cnt, 1) == "1")
-                    {
-                        mantisse = mantisse + faktor;
-                    }
-                }
-                return Math.Pow((-1), vz) * Math.Pow(2, (exd - 127)) * mantisse;
-            }
-        }
+        public static double FromByteArray(byte[] bytes) => Real.FromByteArray(bytes);
 
         /// <summary>
         /// Converts a S7 DInt to double
@@ -74,51 +37,7 @@ namespace S7.Net.Types
         /// <summary>
         /// Converts a double to S7 Real (4 bytes)
         /// </summary>
-        public static byte[] ToByteArray(double value)
-        {
-            double wert = (double)value;
-            string binString = "";
-            byte[] bytes = new byte[4];
-            if (wert != 0f)
-            {
-                if (wert < 0)
-                {
-                    wert *= -1;
-                    binString = "1";
-                }
-                else
-                {
-                    binString = "0";
-                }
-                int exponent = (int)Math.Floor((double)Math.Log(wert) / Math.Log(2.0));
-                wert = wert / (Math.Pow(2, exponent)) - 1;
-
-                binString += ValToBinString((byte)(exponent + 127));
-                for (int cnt = 1; cnt <= 23; cnt++)
-                {
-                    if (!(wert - System.Math.Pow(2, -cnt) < 0))
-                    {
-                        wert = wert - System.Math.Pow(2, -cnt);
-                        binString += "1";
-                    }
-                    else
-                        binString += "0";
-                }
-                bytes[0] = (byte)BinStringToByte(binString.Substring(0, 8));
-                bytes[1] = (byte)BinStringToByte(binString.Substring(8, 8));
-                bytes[2] = (byte)BinStringToByte(binString.Substring(16, 8));
-                bytes[3] = (byte)BinStringToByte(binString.Substring(24, 8));
-
-            }
-            else
-            {
-                bytes[0] = 0;
-                bytes[1] = 0;
-                bytes[2] = 0;
-                bytes[3] = 0;
-            }
-            return bytes;
-        }
+        public static byte[] ToByteArray(double value) => Real.ToByteArray((float)value);
 
         /// <summary>
         /// Converts an array of double to an array of bytes 
@@ -128,7 +47,7 @@ namespace S7.Net.Types
             ByteArray arr = new ByteArray();
             foreach (double val in value)
                 arr.Add(ToByteArray(val));
-            return arr.array;
+            return arr.Array;
         }
 
         /// <summary>
@@ -145,38 +64,5 @@ namespace S7.Net.Types
             return values;
         }
         
-        
-        private static string ValToBinString(byte value)
-        {
-            string txt = "";
-
-            for (int cnt = 7; cnt >= 0; cnt += -1)
-            {
-                if ((value & (byte)Math.Pow(2, cnt)) > 0)
-                    txt += "1";
-                else
-                    txt += "0";
-            }
-            return txt;
-        }
-        
-        private static byte? BinStringToByte(string txt)
-        {
-            int cnt = 0;
-            int ret = 0;
-
-            if (txt.Length == 8)
-            {
-                for (cnt = 7; cnt >= 0; cnt += -1)
-                {
-                    if (int.Parse(txt.Substring(cnt, 1)) == 1)
-                    {
-                        ret += (int)(Math.Pow(2, (txt.Length - 1 - cnt)));
-                    }
-                }
-                return (byte)ret;
-            }
-            return null;
-        }
     }
 }

S7.Net/Types/Int.cs

@@ -10,7 +10,7 @@ namespace S7.Net.Types
         /// <summary>
         /// Converts a S7 Int (2 bytes) to short (Int16)
         /// </summary>
-        public static Int16 FromByteArray(byte[] bytes)
+        public static short FromByteArray(byte[] bytes)
         {
             if (bytes.Length != 2)
             {
@@ -18,16 +18,9 @@ namespace S7.Net.Types
             }
             // bytes[0] -> HighByte
             // bytes[1] -> LowByte
-            return FromBytes(bytes[1], bytes[0]);
+            return (short)((int)(bytes[1]) | ((int)(bytes[0]) << 8));
         }
 
-        /// <summary>
-        /// Converts a S7 Int (2 bytes) to short (Int16)
-        /// </summary>
-        public static Int16 FromBytes(byte LoVal, byte HiVal)
-        {
-            return (Int16)(HiVal * 256 + LoVal);
-        }
 
         /// <summary>
         /// Converts a short (Int16) to a S7 Int byte array (2 bytes)
@@ -35,16 +28,10 @@ namespace S7.Net.Types
         public static byte[] ToByteArray(Int16 value)
         {
             byte[] bytes = new byte[2];
-            int x = 2;
-            long valLong = (long)((Int16)value);
-            for (int cnt = 0; cnt < x; cnt++)
-            {
-                Int64 x1 = (Int64)Math.Pow(256, (cnt));
 
-                Int64 x3 = (Int64)(valLong / x1);
-                bytes[x - cnt - 1] = (byte)(x3 & 255);
-                valLong -= bytes[x - cnt - 1] * x1;
-            }
+            bytes[0] = (byte) (value >> 8 & 0xFF);
+            bytes[1] = (byte)(value & 0xFF);
+
             return bytes;
         }
 
@@ -53,10 +40,15 @@ namespace S7.Net.Types
         /// </summary>
         public static byte[] ToByteArray(Int16[] value)
         {
-            ByteArray arr = new ByteArray();
-            foreach (Int16 val in value)
-                arr.Add(ToByteArray(val));
-            return arr.array;
+            byte[] bytes = new byte[value.Length * 2];
+            int bytesPos = 0;
+
+            for(int i=0; i< value.Length; i++)
+            {
+                bytes[bytesPos++] = (byte)((value[i] >> 8) & 0xFF);
+                bytes[bytesPos++] = (byte) (value[i] & 0xFF);
+            }
+            return bytes;
         }
 
         /// <summary>
@@ -64,10 +56,12 @@ namespace S7.Net.Types
         /// </summary>
         public static Int16[] ToArray(byte[] bytes)
         {
-            Int16[] values = new Int16[bytes.Length / 2];
+            int shortsCount = bytes.Length / 2;
+
+            Int16[] values = new Int16[shortsCount];
 
             int counter = 0;
-            for (int cnt = 0; cnt < bytes.Length / 2; cnt++)
+            for (int cnt = 0; cnt < shortsCount; cnt++)
                 values[cnt] = FromByteArray(new byte[] { bytes[counter++], bytes[counter++] });
 
             return values;

S7.Net/Types/LReal.cs

@@ -0,0 +1,57 @@
+using System;
+using System.IO;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the conversion methods to convert Real from S7 plc to C# double.
+    /// </summary>
+    public static class LReal
+    {
+        /// <summary>
+        /// Converts a S7 LReal (8 bytes) to double
+        /// </summary>
+        public static double FromByteArray(byte[] bytes)
+        {
+            if (bytes.Length != 8)
+            {
+                throw new ArgumentException("Wrong number of bytes. Bytes array must contain 8 bytes.");
+            }
+            var buffer = bytes;
+
+            // sps uses bigending so we have to reverse if platform needs
+            if (BitConverter.IsLittleEndian)
+            {
+                Array.Reverse(buffer);
+            }
+
+            return BitConverter.ToDouble(buffer, 0);
+        }
+
+        /// <summary>
+        /// Converts a double to S7 LReal (8 bytes)
+        /// </summary>
+        public static byte[] ToByteArray(double value)
+        {
+            var bytes = BitConverter.GetBytes(value);
+
+            // sps uses bigending so we have to check if platform is same
+            if (BitConverter.IsLittleEndian)
+            {
+                Array.Reverse(bytes);
+            }
+            return bytes;
+        }
+
+        /// <summary>
+        /// Converts an array of double to an array of bytes 
+        /// </summary>
+        public static byte[] ToByteArray(double[] value) => TypeHelper.ToByteArray(value, ToByteArray);
+
+        /// <summary>
+        /// Converts an array of S7 LReal to an array of double
+        /// </summary>
+        public static double[] ToArray(byte[] bytes) => TypeHelper.ToArray(bytes, FromByteArray);
+        
+    }
+}

S7.Net/Types/Real.cs

@@ -0,0 +1,75 @@
+using System;
+using System.IO;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the conversion methods to convert Real from S7 plc to C# double.
+    /// </summary>
+    public static class Real
+    {
+        /// <summary>
+        /// Converts a S7 Real (4 bytes) to float
+        /// </summary>
+        public static float FromByteArray(byte[] bytes)
+        {
+            if (bytes.Length != 4)
+            {
+                throw new ArgumentException("Wrong number of bytes. Bytes array must contain 4 bytes.");
+            }
+
+            // sps uses bigending so we have to reverse if platform needs
+            if (BitConverter.IsLittleEndian)
+            {
+                // create deep copy of the array and reverse
+                bytes = new byte[] { bytes[3], bytes[2], bytes[1], bytes[0] };
+            }
+
+            return BitConverter.ToSingle(bytes, 0);
+        }
+
+        /// <summary>
+        /// Converts a float to S7 Real (4 bytes)
+        /// </summary>
+        public static byte[] ToByteArray(float value)
+        {
+            byte[] bytes = BitConverter.GetBytes(value);
+
+            // sps uses bigending so we have to check if platform is same
+            if (!BitConverter.IsLittleEndian) return bytes;
+            
+            // create deep copy of the array and reverse
+            return new byte[] { bytes[3], bytes[2], bytes[1], bytes[0] };
+        }
+
+        /// <summary>
+        /// Converts an array of float to an array of bytes 
+        /// </summary>
+        public static byte[] ToByteArray(float[] value)
+        {
+            var buffer = new byte[4 * value.Length];
+            var stream = new MemoryStream(buffer);
+            foreach (var val in value)
+            {
+                stream.Write(ToByteArray(val), 0, 4);
+            }
+
+            return buffer;
+        }
+
+        /// <summary>
+        /// Converts an array of S7 Real to an array of float
+        /// </summary>
+        public static float[] ToArray(byte[] bytes)
+        {
+            var values = new float[bytes.Length / 4];
+
+            int counter = 0;
+            for (int cnt = 0; cnt < bytes.Length / 4; cnt++)
+                values[cnt] = FromByteArray(new byte[] { bytes[counter++], bytes[counter++], bytes[counter++], bytes[counter++] });
+
+            return values;
+        }
+        
+    }
+}

S7.Net/Types/S7String.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Text;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the methods to convert from S7 strings to C# strings
+    /// An S7 String has a preceeding 2 byte header containing its capacity and length
+    /// </summary>
+    public static class S7String
+    {
+        private static Encoding stringEncoding = Encoding.ASCII;
+
+        /// <summary>
+        /// The Encoding used when serializing and deserializing S7String (Encoding.ASCII by default)
+        /// </summary>
+        /// <exception cref="ArgumentNullException">StringEncoding must not be null</exception>
+        public static Encoding StringEncoding
+        {
+            get => stringEncoding;
+            set => stringEncoding = value ?? throw new ArgumentNullException(nameof(StringEncoding));
+        }
+
+        /// <summary>
+        /// Converts S7 bytes to a string
+        /// </summary>
+        /// <param name="bytes"></param>
+        /// <returns></returns>
+        public static string FromByteArray(byte[] bytes)
+        {
+            if (bytes.Length < 2)
+            {
+                throw new PlcException(ErrorCode.ReadData, "Malformed S7 String / too short");
+            }
+
+            int size = bytes[0];
+            int length = bytes[1];
+            if (length > size)
+            {
+                throw new PlcException(ErrorCode.ReadData, "Malformed S7 String / length larger than capacity");
+            }
+
+            try
+            {
+                return StringEncoding.GetString(bytes, 2, length);
+            }
+            catch (Exception e)
+            {
+                throw new PlcException(ErrorCode.ReadData,
+                    $"Failed to parse {VarType.S7String} from data. Following fields were read: size: '{size}', actual length: '{length}', total number of bytes (including header): '{bytes.Length}'.",
+                    e);
+            }
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:string"/> to S7 string with 2-byte header.
+        /// </summary>
+        /// <param name="value">The string to convert to byte array.</param>
+        /// <param name="reservedLength">The length (in characters) allocated in PLC for the string.</param>
+        /// <returns>A <see cref="T:byte[]" /> containing the string header and string value with a maximum length of <paramref name="reservedLength"/> + 2.</returns>
+        public static byte[] ToByteArray(string? value, int reservedLength)
+        {
+            if (value is null)
+            {
+                throw new ArgumentNullException(nameof(value));
+            }
+
+            if (reservedLength > 254) throw new ArgumentException($"The maximum string length supported is 254.");
+
+            var bytes = StringEncoding.GetBytes(value);
+            if (bytes.Length > reservedLength) throw new ArgumentException($"The provided string length ({bytes.Length} is larger than the specified reserved length ({reservedLength}).");
+
+            var buffer = new byte[2 + reservedLength];
+            Array.Copy(bytes, 0, buffer, 2, bytes.Length);
+            buffer[0] = (byte)reservedLength;
+            buffer[1] = (byte)bytes.Length;
+            return buffer;
+        }
+    }
+}

S7.Net/Types/S7StringAttribute.cs

@@ -0,0 +1,67 @@
+using System;
+
+namespace S7.Net.Types
+{
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false)]
+    public sealed class S7StringAttribute : Attribute
+    {
+        private readonly S7StringType type;
+        private readonly int reservedLength;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="S7StringAttribute"/> class.
+        /// </summary>
+        /// <param name="type">The string type.</param>
+        /// <param name="reservedLength">Reserved length of the string in characters.</param>
+        /// <exception cref="ArgumentException">Please use a valid value for the string type</exception>
+        public S7StringAttribute(S7StringType type, int reservedLength)
+        {
+            if (!Enum.IsDefined(typeof(S7StringType), type))
+                throw new ArgumentException("Please use a valid value for the string type");
+
+            this.type = type;
+            this.reservedLength = reservedLength;
+        }
+
+        /// <summary>
+        /// Gets the type of the string.
+        /// </summary>
+        /// <value>
+        /// The string type.
+        /// </value>
+        public S7StringType Type => type;
+
+        /// <summary>
+        /// Gets the reserved length of the string in characters.
+        /// </summary>
+        /// <value>
+        /// The reserved length of the string in characters.
+        /// </value>
+        public int ReservedLength => reservedLength;
+
+        /// <summary>
+        /// Gets the reserved length in bytes.
+        /// </summary>
+        /// <value>
+        /// The reserved length in bytes.
+        /// </value>
+        public int ReservedLengthInBytes => type == S7StringType.S7String ? reservedLength + 2 : (reservedLength * 2) + 4;
+    }
+
+
+    /// <summary>
+    /// String type.
+    /// </summary>
+    public enum S7StringType
+    {
+        /// <summary>
+        /// ASCII string.
+        /// </summary>
+        S7String = VarType.S7String,
+
+        /// <summary>
+        /// Unicode string.
+        /// </summary>
+        S7WString = VarType.S7WString
+    }
+}

S7.Net/Types/S7WString.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Text;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the methods to convert from S7 wstrings to C# strings
+    /// An S7 WString has a preceding 4 byte header containing its capacity and length
+    /// </summary>
+    public static class S7WString
+    {
+        /// <summary>
+        /// Converts S7 bytes to a string
+        /// </summary>
+        /// <param name="bytes"></param>
+        /// <returns></returns>
+        public static string FromByteArray(byte[] bytes)
+        {
+            if (bytes.Length < 4)
+            {
+                throw new PlcException(ErrorCode.ReadData, "Malformed S7 WString / too short");
+            }
+
+            int size = (bytes[0] << 8) | bytes[1];
+            int length = (bytes[2] << 8) | bytes[3];
+
+            if (length > size)
+            {
+                throw new PlcException(ErrorCode.ReadData, "Malformed S7 WString / length larger than capacity");
+            }
+
+            try
+            {
+                return Encoding.BigEndianUnicode.GetString(bytes, 4, length * 2);
+            }
+            catch (Exception e)
+            {
+                throw new PlcException(ErrorCode.ReadData,
+                    $"Failed to parse {VarType.S7WString} from data. Following fields were read: size: '{size}', actual length: '{length}', total number of bytes (including header): '{bytes.Length}'.",
+                    e);
+            }
+            
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:string"/> to S7 wstring with 4-byte header.
+        /// </summary>
+        /// <param name="value">The string to convert to byte array.</param>
+        /// <param name="reservedLength">The length (in characters) allocated in PLC for the string.</param>
+        /// <returns>A <see cref="T:byte[]" /> containing the string header and string value with a maximum length of <paramref name="reservedLength"/> + 4.</returns>
+        public static byte[] ToByteArray(string? value, int reservedLength)
+        {
+            if (value is null)
+            {
+                throw new ArgumentNullException(nameof(value));
+            }
+
+            if (reservedLength > 16382) throw new ArgumentException("The maximum string length supported is 16382.");
+            
+            var buffer = new byte[4 + reservedLength * 2];
+            buffer[0] = (byte)((reservedLength >> 8) & 0xFF);
+            buffer[1] = (byte)(reservedLength & 0xFF);
+            buffer[2] = (byte)((value.Length >> 8) & 0xFF);
+            buffer[3] = (byte)(value.Length & 0xFF);
+
+            var stringLength = Encoding.BigEndianUnicode.GetBytes(value, 0, value.Length, buffer, 4) / 2;
+            if (stringLength > reservedLength) throw new ArgumentException($"The provided string length ({stringLength} is larger than the specified reserved length ({reservedLength}).");
+
+            return buffer;
+        }
+    }
+}

S7.Net/Types/Single.cs

@@ -0,0 +1,68 @@
+using System;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the conversion methods to convert Real from S7 plc to C# float.
+    /// </summary>
+    [Obsolete("Class Single is obsolete. Use Real instead.")]
+    public static class Single
+    {
+        /// <summary>
+        /// Converts a S7 Real (4 bytes) to float
+        /// </summary>
+        public static float FromByteArray(byte[] bytes) => Real.FromByteArray(bytes);
+
+        /// <summary>
+        /// Converts a S7 DInt to float
+        /// </summary>
+        public static float FromDWord(Int32 value)
+        {
+            byte[] b = DInt.ToByteArray(value);
+            float d = FromByteArray(b);
+            return d;
+        }
+
+        /// <summary>
+        /// Converts a S7 DWord to float
+        /// </summary>
+        public static float FromDWord(UInt32 value)
+        {
+            byte[] b = DWord.ToByteArray(value);
+            float d = FromByteArray(b);
+            return d;
+        }
+
+
+        /// <summary>
+        /// Converts a double to S7 Real (4 bytes)
+        /// </summary>
+        public static byte[] ToByteArray(float value) => Real.ToByteArray(value);
+
+        /// <summary>
+        /// Converts an array of float to an array of bytes 
+        /// </summary>
+        public static byte[] ToByteArray(float[] value)
+        {
+            ByteArray arr = new ByteArray();
+            foreach (float val in value)
+                arr.Add(ToByteArray(val));
+            return arr.Array;
+        }
+
+        /// <summary>
+        /// Converts an array of S7 Real to an array of float
+        /// </summary>
+        public static float[] ToArray(byte[] bytes)
+        {
+            float[] values = new float[bytes.Length / 4];
+
+            int counter = 0;
+            for (int cnt = 0; cnt < bytes.Length / 4; cnt++)
+                values[cnt] = FromByteArray(new byte[] { bytes[counter++], bytes[counter++], bytes[counter++], bytes[counter++] });
+
+            return values;
+        }
+        
+    }
+}

S7.Net/Types/String.cs

@@ -1,20 +1,27 @@
 namespace S7.Net.Types
 {
     /// <summary>
-    /// Contains the methods to convert from S7 strings to C# strings
+    /// Contains the methods to convert from S7 Array of Chars (like a const char[N] C-String) to C# strings
     /// </summary>
-    public static class String
+    public class String
     {
         /// <summary>
-        /// Converts a string to S7 bytes
+        /// Converts a string to <paramref name="reservedLength"/> of bytes, padded with 0-bytes if required.
         /// </summary>
-        public static byte[] ToByteArray(string value)
+        /// <param name="value">The string to write to the PLC.</param>
+        /// <param name="reservedLength">The amount of bytes reserved for the <paramref name="value"/> in the PLC.</param>
+        public static byte[] ToByteArray(string value, int reservedLength)
         {
-            string txt = (string)value;
-            char[] ca = txt.ToCharArray();
-            byte[] bytes = new byte[txt.Length];
-            for (int cnt = 0; cnt <= ca.Length - 1; cnt++)
-                bytes[cnt] = (byte)Asc(ca[cnt].ToString());
+            var bytes = new byte[reservedLength];
+            if (value == null) return bytes;
+
+            var length = value.Length;
+            if (length == 0) return bytes;
+
+            if (length > reservedLength) length = reservedLength;
+
+            System.Text.Encoding.ASCII.GetBytes(value, 0, length, bytes, 0);
+
             return bytes;
         }
         
@@ -27,13 +34,6 @@
         {
             return System.Text.Encoding.ASCII.GetString(bytes);
         }
-        
-        private static int Asc(string s)
-        {
-            byte[] b = System.Text.Encoding.ASCII.GetBytes(s);
-            if (b.Length > 0)
-                return b[0];
-            return 0;
-        }
+
     }
 }

S7.Net/Types/StringEx.cs

@@ -0,0 +1,15 @@
+using System;
+
+namespace S7.Net.Types
+{
+    /// <inheritdoc cref="S7String"/>
+    [Obsolete("Please use S7String class")]
+    public static class StringEx
+    {
+        /// <inheritdoc cref="S7String.FromByteArray(byte[])"/>
+        public static string FromByteArray(byte[] bytes) => S7String.FromByteArray(bytes);
+
+        /// <inheritdoc cref="S7String.ToByteArray(string, int)"/>
+        public static byte[] ToByteArray(string value, int reservedLength) => S7String.ToByteArray(value, reservedLength);
+    }
+}

S7.Net/Types/Struct.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Linq;
-using System.Globalization;
 using System.Reflection;
 
 namespace S7.Net.Types
@@ -19,8 +18,14 @@ namespace S7.Net.Types
         {
             double numBytes = 0.0;
 
-            System.Reflection.FieldInfo[] infos = structType.GetFields();
-            foreach (System.Reflection.FieldInfo info in infos)
+            var infos = structType
+#if NETSTANDARD1_3
+                .GetTypeInfo().DeclaredFields;
+#else
+                .GetFields();
+#endif
+
+            foreach (var info in infos)
             {
                 switch (info.FieldType.Name)
                 {
@@ -40,18 +45,34 @@ namespace S7.Net.Types
                         break;
                     case "Int32":
                     case "UInt32":
+                    case "TimeSpan":
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
                         numBytes += 4;
                         break;
-                    case "Float": 
-                    case "Double":
+                    case "Single":
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
                         numBytes += 4;
                         break;
+                    case "Double":
+                        numBytes = Math.Ceiling(numBytes);
+                        if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                            numBytes++;
+                        numBytes += 8;
+                        break;
+                    case "String":
+                        S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                        if (attribute == default(S7StringAttribute))
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                        numBytes = Math.Ceiling(numBytes);
+                        if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                            numBytes++;
+                        numBytes += attribute.ReservedLengthInBytes;
+                        break;
                     default:
                         numBytes += GetStructSize(info.FieldType);
                         break;
@@ -66,7 +87,7 @@ namespace S7.Net.Types
         /// <param name="structType">The struct type</param>
         /// <param name="bytes">The array of bytes</param>
         /// <returns>The object depending on the struct type or null if fails(array-length != struct-length</returns>
-        public static object FromBytes(Type structType, byte[] bytes)
+        public static object? FromBytes(Type structType, byte[] bytes)
         {
             if (bytes == null)
                 return null;
@@ -78,10 +99,17 @@ namespace S7.Net.Types
             int bytePos = 0;
             int bitPos = 0;
             double numBytes = 0.0;
-            object structValue = Activator.CreateInstance(structType);
+            object structValue = Activator.CreateInstance(structType) ??
+                throw new ArgumentException($"Failed to create an instance of the type {structType}.", nameof(structType));
 
-            System.Reflection.FieldInfo[] infos = structValue.GetType().GetFields();
-            foreach (System.Reflection.FieldInfo info in infos)
+            var infos = structValue.GetType()
+#if NETSTANDARD1_3
+                .GetTypeInfo().DeclaredFields;
+#else
+                .GetFields();
+#endif
+
+            foreach (var info in infos)
             {
                 switch (info.FieldType.Name)
                 {
@@ -104,7 +132,7 @@ namespace S7.Net.Types
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
-                        // hier auswerten
+                        // get the value
                         ushort source = Word.FromBytes(bytes[(int)numBytes + 1], bytes[(int)numBytes]);
                         info.SetValue(structValue, source.ConvertToShort());
                         numBytes += 2;
@@ -113,7 +141,7 @@ namespace S7.Net.Types
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
-                        // hier auswerten
+                        // get the value
                         info.SetValue(structValue, Word.FromBytes(bytes[(int)numBytes + 1],
                                                                           bytes[(int)numBytes]));
                         numBytes += 2;
@@ -122,34 +150,85 @@ namespace S7.Net.Types
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
-                        // hier auswerten
+                        // get the value
                         uint sourceUInt = DWord.FromBytes(bytes[(int)numBytes + 3],
                                                                            bytes[(int)numBytes + 2],
                                                                            bytes[(int)numBytes + 1],
-                                                                           bytes[(int)numBytes + 0]);                        
-                        info.SetValue(structValue, sourceUInt.ConvertToInt());                       
+                                                                           bytes[(int)numBytes + 0]);
+                        info.SetValue(structValue, sourceUInt.ConvertToInt());
                         numBytes += 4;
                         break;
                     case "UInt32":
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
-                        // hier auswerten
+                        // get the value
                         info.SetValue(structValue, DWord.FromBytes(bytes[(int)numBytes],
                                                                            bytes[(int)numBytes + 1],
                                                                            bytes[(int)numBytes + 2],
                                                                            bytes[(int)numBytes + 3]));
                         numBytes += 4;
                         break;
+                    case "Single":
+                        numBytes = Math.Ceiling(numBytes);
+                        if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                            numBytes++;
+                        // get the value
+                        info.SetValue(structValue, Real.FromByteArray(new byte[] { bytes[(int)numBytes],
+                                                                           bytes[(int)numBytes + 1],
+                                                                           bytes[(int)numBytes + 2],
+                                                                           bytes[(int)numBytes + 3] }));
+                        numBytes += 4;
+                        break;
                     case "Double":
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                             numBytes++;
-                        // hier auswerten
-                        info.SetValue(structValue, Double.FromByteArray(new byte[] { bytes[(int)numBytes],
-                                                                           bytes[(int)numBytes + 1],
-                                                                           bytes[(int)numBytes + 2],
-                                                                           bytes[(int)numBytes + 3] }));
+                        // get the value
+                        var data = new byte[8];
+                        Array.Copy(bytes, (int)numBytes, data, 0, 8);
+                        info.SetValue(structValue, LReal.FromByteArray(data));
+                        numBytes += 8;
+                        break;
+                    case "String":
+                        S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                        if (attribute == default(S7StringAttribute))
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                        numBytes = Math.Ceiling(numBytes);
+                        if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                            numBytes++;
+
+                        // get the value
+                        var sData = new byte[attribute.ReservedLengthInBytes];
+                        Array.Copy(bytes, (int)numBytes, sData, 0, sData.Length);
+                        switch (attribute.Type)
+                        {
+                            case S7StringType.S7String:
+                                info.SetValue(structValue, S7String.FromByteArray(sData));
+                                break;
+                            case S7StringType.S7WString:
+                                info.SetValue(structValue, S7WString.FromByteArray(sData));
+                                break;
+                            default:
+                                throw new ArgumentException("Please use a valid string type for the S7StringAttribute");
+                        }
+
+                        numBytes += sData.Length;
+                        break;
+                    case "TimeSpan":
+                        numBytes = Math.Ceiling(numBytes);
+                        if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
+                            numBytes++;
+                        
+                        // get the value
+                        info.SetValue(structValue, TimeSpan.FromByteArray(new[] 
+                        {
+                            bytes[(int)numBytes + 0],
+                            bytes[(int)numBytes + 1],
+                            bytes[(int)numBytes + 2],
+                            bytes[(int)numBytes + 3]
+                        }));
                         numBytes += 4;
                         break;
                     default:
@@ -176,15 +255,29 @@ namespace S7.Net.Types
 
             int size = Struct.GetStructSize(type);
             byte[] bytes = new byte[size];
-            byte[] bytes2 = null;
+            byte[]? bytes2 = null;
 
             int bytePos = 0;
             int bitPos = 0;
             double numBytes = 0.0;
 
-            System.Reflection.FieldInfo[] infos = type.GetFields();
-            foreach (System.Reflection.FieldInfo info in infos)
+            var infos = type
+#if NETSTANDARD1_3
+                .GetTypeInfo().DeclaredFields;
+#else
+                .GetFields();
+#endif
+
+            foreach (var info in infos)
             {
+                static TValue GetValueOrThrow<TValue>(FieldInfo fi, object structValue) where TValue : struct
+                {
+                    var value = fi.GetValue(structValue) as TValue? ??
+                        throw new ArgumentException($"Failed to convert value of field {fi.Name} of {structValue} to type {typeof(TValue)}");
+
+                    return value;
+                }
+
                 bytes2 = null;
                 switch (info.FieldType.Name)
                 {
@@ -192,7 +285,7 @@ namespace S7.Net.Types
                         // get the value
                         bytePos = (int)Math.Floor(numBytes);
                         bitPos = (int)((numBytes - (double)bytePos) / 0.125);
-                        if ((bool)info.GetValue(structValue))
+                        if (GetValueOrThrow<bool>(info, structValue))
                             bytes[bytePos] |= (byte)Math.Pow(2, bitPos);            // is true
                         else
                             bytes[bytePos] &= (byte)(~(byte)Math.Pow(2, bitPos));   // is false
@@ -201,23 +294,41 @@ namespace S7.Net.Types
                     case "Byte":
                         numBytes = (int)Math.Ceiling(numBytes);
                         bytePos = (int)numBytes;
-                        bytes[bytePos] = (byte)info.GetValue(structValue);
+                        bytes[bytePos] = GetValueOrThrow<byte>(info, structValue);
                         numBytes++;
                         break;
                     case "Int16":
-                        bytes2 = Int.ToByteArray((Int16)info.GetValue(structValue));
+                        bytes2 = Int.ToByteArray(GetValueOrThrow<short>(info, structValue));
                         break;
                     case "UInt16":
-                        bytes2 = Word.ToByteArray((UInt16)info.GetValue(structValue));
+                        bytes2 = Word.ToByteArray(GetValueOrThrow<ushort>(info, structValue));
                         break;
                     case "Int32":
-                        bytes2 = DInt.ToByteArray((Int32)info.GetValue(structValue));
+                        bytes2 = DInt.ToByteArray(GetValueOrThrow<int>(info, structValue));
                         break;
                     case "UInt32":
-                        bytes2 = DWord.ToByteArray((UInt32)info.GetValue(structValue));
+                        bytes2 = DWord.ToByteArray(GetValueOrThrow<uint>(info, structValue));
+                        break;
+                    case "Single":
+                        bytes2 = Real.ToByteArray(GetValueOrThrow<float>(info, structValue));
                         break;
                     case "Double":
-                        bytes2 = Double.ToByteArray((double)info.GetValue(structValue));
+                        bytes2 = LReal.ToByteArray(GetValueOrThrow<double>(info, structValue));
+                        break;
+                    case "String":
+                        S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
+                        if (attribute == default(S7StringAttribute))
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
+
+                        bytes2 = attribute.Type switch
+                        {
+                            S7StringType.S7String => S7String.ToByteArray((string?)info.GetValue(structValue), attribute.ReservedLength),
+                            S7StringType.S7WString => S7WString.ToByteArray((string?)info.GetValue(structValue), attribute.ReservedLength),
+                            _ => throw new ArgumentException("Please use a valid string type for the S7StringAttribute")
+                        };
+                        break;
+                    case "TimeSpan":
+                        bytes2 = TimeSpan.ToByteArray((System.TimeSpan)info.GetValue(structValue));
                         break;
                 }
                 if (bytes2 != null)
@@ -227,14 +338,12 @@ namespace S7.Net.Types
                     if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
                         numBytes++;
                     bytePos = (int)numBytes;
-                    for (int bCnt=0; bCnt<bytes2.Length; bCnt++)
+                    for (int bCnt = 0; bCnt < bytes2.Length; bCnt++)
                         bytes[bytePos + bCnt] = bytes2[bCnt];
                     numBytes += bytes2.Length;
                 }
             }
             return bytes;
         }
-
-       
     }
 }

S7.Net/Types/TimeSpan.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Collections.Generic;
+
+namespace S7.Net.Types
+{
+    /// <summary>
+    /// Contains the methods to convert between <see cref="T:System.TimeSpan"/> and S7 representation of TIME values.
+    /// </summary>
+    public static class TimeSpan
+    {
+        /// <summary>
+        /// The minimum <see cref="T:System.TimeSpan"/> value supported by the specification.
+        /// </summary>
+        public static readonly System.TimeSpan SpecMinimumTimeSpan = System.TimeSpan.FromMilliseconds(int.MinValue);
+
+        /// <summary>
+        /// The maximum <see cref="T:System.TimeSpan"/> value supported by the specification.
+        /// </summary>
+        public static readonly System.TimeSpan SpecMaximumTimeSpan = System.TimeSpan.FromMilliseconds(int.MaxValue);
+
+        /// <summary>
+        /// Parses a <see cref="T:System.TimeSpan"/> value from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>A <see cref="T:System.TimeSpan"/> object representing the value read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the length of
+        ///   <paramref name="bytes"/> is not 4 or any value in <paramref name="bytes"/>
+        ///   is outside the valid range of values.</exception>
+        public static System.TimeSpan FromByteArray(byte[] bytes)
+        {
+            var milliseconds = DInt.FromByteArray(bytes);
+            return System.TimeSpan.FromMilliseconds(milliseconds);
+        }
+
+        /// <summary>
+        /// Parses an array of <see cref="T:System.TimeSpan"/> values from bytes.
+        /// </summary>
+        /// <param name="bytes">Input bytes read from PLC.</param>
+        /// <returns>An array of <see cref="T:System.TimeSpan"/> objects representing the values read from PLC.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the length of
+        ///   <paramref name="bytes"/> is not a multiple of 4 or any value in
+        ///   <paramref name="bytes"/> is outside the valid range of values.</exception>
+        public static System.TimeSpan[] ToArray(byte[] bytes)
+        {
+            const int singleTimeSpanLength = 4;
+            
+            if (bytes.Length % singleTimeSpanLength != 0)
+                throw new ArgumentOutOfRangeException(nameof(bytes), bytes.Length,
+                    $"Parsing an array of {nameof(System.TimeSpan)} requires a multiple of {singleTimeSpanLength} bytes of input data, input data is '{bytes.Length}' long.");
+
+            var result = new System.TimeSpan[bytes.Length / singleTimeSpanLength];
+
+            var milliseconds = DInt.ToArray(bytes);
+            for (var i = 0; i < milliseconds.Length; i++)
+                result[i] = System.TimeSpan.FromMilliseconds(milliseconds[i]);
+
+            return result;
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:System.TimeSpan"/> value to a byte array.
+        /// </summary>
+        /// <param name="timeSpan">The TimeSpan value to convert.</param>
+        /// <returns>A byte array containing the S7 date time representation of <paramref name="timeSpan"/>.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when the value of
+        ///   <paramref name="timeSpan"/> is before <see cref="P:SpecMinimumTimeSpan"/>
+        ///   or after <see cref="P:SpecMaximumTimeSpan"/>.</exception>
+        public static byte[] ToByteArray(System.TimeSpan timeSpan)
+        {
+            if (timeSpan < SpecMinimumTimeSpan)
+                throw new ArgumentOutOfRangeException(nameof(timeSpan), timeSpan,
+                    $"Time span '{timeSpan}' is before the minimum '{SpecMinimumTimeSpan}' supported in S7 time representation.");
+
+            if (timeSpan > SpecMaximumTimeSpan)
+                throw new ArgumentOutOfRangeException(nameof(timeSpan), timeSpan,
+                    $"Time span '{timeSpan}' is after the maximum '{SpecMaximumTimeSpan}' supported in S7 time representation.");
+
+            return DInt.ToByteArray(Convert.ToInt32(timeSpan.TotalMilliseconds));
+        }
+
+        /// <summary>
+        /// Converts an array of <see cref="T:System.TimeSpan"/> values to a byte array.
+        /// </summary>
+        /// <param name="timeSpans">The TimeSpan values to convert.</param>
+        /// <returns>A byte array containing the S7 date time representations of <paramref name="timeSpans"/>.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when any value of
+        ///   <paramref name="timeSpans"/> is before <see cref="P:SpecMinimumTimeSpan"/>
+        ///   or after <see cref="P:SpecMaximumTimeSpan"/>.</exception>
+        public static byte[] ToByteArray(System.TimeSpan[] timeSpans)
+        {
+            var bytes = new List<byte>(timeSpans.Length * 4);
+            foreach (var timeSpan in timeSpans) bytes.AddRange(ToByteArray(timeSpan));
+
+            return bytes.ToArray();
+        }
+    }
+}