diff --git a/S7.Net/PLC.cs b/S7.Net/PLC.cs
index ece06e9..67ad57a 100644
--- a/S7.Net/PLC.cs
+++ b/S7.Net/PLC.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Net;
 using System.Net.NetworkInformation;
@@ -17,31 +18,32 @@ namespace S7.Net
     public class Plc : IDisposable
     {
         private const int CONNECTION_TIMED_OUT_ERROR_CODE = 10060;
-
-        private Socket _mSocket; //TCP connection to device
+        
+        //TCP connection to device
+        private Socket _mSocket;
 
         /// <summary>
-        /// Ip address of the plc
+        /// IP address of the PLC
         /// </summary>
         public string IP { get; private set; }
 
         /// <summary>
-        /// Cpu type of the plc
+        /// CPU type of the PLC
         /// </summary>
         public CpuType CPU { get; private set; }
 
         /// <summary>
-        /// Rack of the plc
+        /// Rack of the PLC
         /// </summary>
         public Int16 Rack { get; private set; }
 
         /// <summary>
-        /// Slot of the CPU of the plc
+        /// Slot of the CPU of the PLC
         /// </summary>
         public Int16 Slot { get; private set; }
         
         /// <summary>
-        /// Returns true if a connection to the plc can be established
+        /// Returns true if a connection to the PLC can be established
         /// </summary>
         public bool IsAvailable
         {
@@ -61,7 +63,7 @@ namespace S7.Net
 
 
         /// <summary>
-        /// Checks if the socket is connected and polls the other peer (the plc) to see if it's connected.
+        /// Checks if the socket is connected and polls the other peer (the PLC) to see if it's connected.
         /// This is the variable that you should continously check to see if the communication is working
         /// See also: http://stackoverflow.com/questions/2661764/how-to-check-if-a-socket-is-connected-disconnected-in-c
         /// </summary>
@@ -100,15 +102,21 @@ namespace S7.Net
         /// You need slot > 0 if you are connecting to external ethernet card (CP).
         /// For S7-300 and S7-400 the default is rack = 0 and slot = 2.
         /// </summary>
-        /// <param name="cpu">CpuType of the plc (select from the enum)</param>
-        /// <param name="ip">Ip address of the plc</param>
-        /// <param name="rack">rack of the plc, usually it's 0, but check in the hardware configuration of Step7 or TIA portal</param>
-        /// <param name="slot">slot of the CPU of the plc, usually it's 2 for S7300-S7400, 0 for S7-1200 and S7-1500.
+        /// <param name="cpu">CpuType of the PLC (select from the enum)</param>
+        /// <param name="ip">Ip address of the PLC</param>
+        /// <param name="rack">rack of the PLC, usually it's 0, but check in the hardware configuration of Step7 or TIA portal</param>
+        /// <param name="slot">slot of the CPU of the PLC, usually it's 2 for S7300-S7400, 0 for S7-1200 and S7-1500.
         ///  If you use an external ethernet card, this must be set accordingly.</param>
         public Plc(CpuType cpu, string ip, Int16 rack, Int16 slot)
         {
-            IP = ip;
+            if (!Enum.IsDefined(typeof(CpuType), cpu))
+                throw new InvalidEnumArgumentException(nameof(cpu), (int) cpu, typeof(CpuType));
+
+            if (string.IsNullOrEmpty(ip))
+                throw new ArgumentException("IP address must valid.", nameof(ip));
+
             CPU = cpu;
+            IP = ip;
             Rack = rack;
             Slot = slot;
         }
@@ -146,7 +154,8 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Open a socket and connects to the plc, sending all the corrected package and returning if the connection was successful (ErroreCode.NoError) of it was wrong.
+        /// Open a <see cref="Socket"/> and connects to the PLC, sending all the corrected package
+        /// and returning if the connection was successful (<see cref="ErrorCode.NoError"/>) of it was wrong.
         /// </summary>
         /// <returns>Returns ErrorCode.NoError if the connection was successful, otherwise check the ErrorCode</returns>
         public ErrorCode Open()
@@ -237,7 +246,7 @@ namespace S7.Net
             catch(Exception exc)
             {
                 LastErrorCode = ErrorCode.ConnectionError;
-                LastErrorString = "Couldn't establish the connection to " + IP + ".\nMessage: " + exc.Message;
+                LastErrorString = string.Format("Couldn't establish the connection to {0}.\nMessage: {1}", IP, exc.Message);
                 return ErrorCode.ConnectionError;
             }
 
@@ -245,7 +254,7 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Disonnects from the plc and close the socket
+        /// Disonnects from the PLC and close the socket
         /// </summary>
         public void Close()
         {
@@ -268,8 +277,10 @@ namespace S7.Net
         {
             int cntBytes = dataItems.Sum(dataItem => VarTypeToByteLength(dataItem.VarType, dataItem.Count));
             
-            if (dataItems.Count > 20) throw new Exception("Too many vars requested");
-            if (cntBytes > 222) throw new Exception("Too many bytes requested"); //todo, proper TDU check + split in multiple requests
+            if (dataItems.Count > 20)
+                throw new Exception("Too many vars requested");
+            if (cntBytes > 222)
+                throw new Exception("Too many bytes requested"); // TODO: proper TDU check + split in multiple requests
 
             try
             {
@@ -287,7 +298,8 @@ namespace S7.Net
 
                 byte[] bReceive = new byte[512];
                 int numReceived = _mSocket.Receive(bReceive, 512, SocketFlags.None);
-                if (bReceive[21] != 0xff) throw new Exception(ErrorCode.WrongNumberReceivedBytes.ToString());
+                if (bReceive[21] != 0xff)
+                    throw new Exception(ErrorCode.WrongNumberReceivedBytes.ToString());
 
                 int offset = 25;
                 foreach (var dataItem in dataItems)
@@ -365,7 +377,7 @@ namespace S7.Net
         }
         
         /// <summary>
-        /// Reads a single variable from the plc, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// 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>
@@ -487,7 +499,8 @@ namespace S7.Net
                         }
 
                         string txt2 = txt.Substring(1);
-                        if (txt2.IndexOf(".") == -1) throw new Exception();
+                        if (txt2.IndexOf(".") == -1)
+                            throw new Exception();
 
                         mByte = int.Parse(txt2.Substring(0, txt2.IndexOf(".")));
                         mBit = int.Parse(txt2.Substring(txt2.IndexOf(".") + 1));
@@ -535,7 +548,7 @@ namespace S7.Net
         }
 
         /// <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. 
+        /// 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>       
@@ -559,28 +572,28 @@ namespace S7.Net
         }
 
         /// <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. 
+        /// 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>
+        /// <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. 
+        /// 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>
+        /// <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();
@@ -688,7 +701,7 @@ namespace S7.Net
                 {
                     var intValue = (int) value;
                     if (intValue < 0 || intValue > 7)
-                        throw new Exception(string.Format("Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid", bitAdr));
+                        throw new ArgumentOutOfRangeException(string.Format("Addressing Error: You can only reference bitwise locations 0-7. Address {0} is invalid", bitAdr), nameof(bitAdr));
 
                     bitValue = intValue == 1;
                 }
@@ -749,11 +762,11 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Writes a single variable from the plc, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
-        /// If the write was not successful, check LastErrorCode or LastErrorString.
+        /// Writes a single variable from the PLC, takes in input strings like "DB1.DBX0.0", "DB20.DBD200", "MB20", "T45", etc.
+        /// If the write was not successful, check <see cref="LastErrorCode"/> or <see cref="LastErrorString"/>.
         /// </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="value">Value to be written to the PLC</param>
         /// <returns>NoError if it was successful, or the error is specified</returns>
         public ErrorCode Write(string variable, object value)
         {
@@ -911,17 +924,17 @@ namespace S7.Net
             catch(Exception exc)
             {
                 LastErrorCode = ErrorCode.WrongVarFormat;
-                LastErrorString = "The variable'" + variable + "' could not be parsed. Please check the syntax and try again.\nException: " + exc.Message;
+                LastErrorString = string.Format("The variable'{0}' could not be parsed. Please check the syntax and try again.\nException: {1}", variable, exc.Message);
                 return LastErrorCode;
             }
         }
 
         /// <summary>
-        /// Writes a C# struct to a DB in the plc
+        /// 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="startByteAdr">Start bytes on the PLC</param>
         /// <returns>NoError if it was successful, or the error is specified</returns>
         public ErrorCode WriteStruct(object structValue, int db, int startByteAdr = 0)
         {
@@ -931,11 +944,11 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Writes a C# class to a DB in the plc
+        /// 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="startByteAdr">Start bytes on the PLC</param>
         /// <returns>NoError if it was successful, or the error is specified</returns>
         public ErrorCode WriteClass(object classValue, int db, int startByteAdr = 0)
         {
@@ -945,7 +958,7 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Sets the LastErrorCode to NoError and LastErrorString to String.Empty
+        /// Sets the <see cref="LastErrorCode"/> to <see cref="ErrorCode.NoError"/> and <see cref="LastErrorString"/> to <see cref="string.Empty"/>.
         /// </summary>
         public void ClearLastError()
         {
@@ -954,7 +967,7 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Creates the header to read bytes from the plc
+        /// Creates the header to read bytes from the PLC
         /// </summary>
         /// <param name="amount"></param>
         /// <returns></returns>
@@ -976,7 +989,7 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Create the bytes-package to request data from the plc. You have to specify the memory type (dataType), 
+        /// 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="dataType">MemoryType (DB, Timer, Counter, etc.)</param>
@@ -1059,7 +1072,7 @@ namespace S7.Net
         }
 
         /// <summary>
-        /// Writes up to 200 bytes to the plc and returns NoError if successful. You must specify the memory area type, memory are address, byte start address and bytes count.
+        /// Writes up to 200 bytes to the PLC and returns NoError if successful. You must specify the memory area type, memory are address, byte start address and bytes count.
         /// 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>
@@ -1139,7 +1152,7 @@ namespace S7.Net
                 package.Add(Types.Word.ToByteArray((ushort)varCount));
                 package.Add(Types.Word.ToByteArray((ushort)(db)));
                 package.Add((byte)dataType);
-                var overflow = (int)(startByteAdr * 8 / 0xffffU); // handles words with address bigger than 8191
+                int overflow = (int)(startByteAdr * 8 / 0xffffU); // handles words with address bigger than 8191
                 package.Add((byte)overflow);
                 package.Add(Types.Word.ToByteArray((ushort)(startByteAdr * 8 + bitAdr)));
                 package.Add(new byte[] { 0, 0x03 }); //ending 0x03 is used for writing a sinlge bit
@@ -1176,7 +1189,8 @@ namespace S7.Net
         /// <returns></returns>
         private object ParseBytes(VarType varType, byte[] bytes, int varCount, byte bitAdr = 0)
         {
-            if (bytes == null) return null;
+            if (bytes == null)
+                return null;
 
             switch (varType)
             {
@@ -1228,23 +1242,27 @@ namespace S7.Net
                         return Types.Counter.ToArray(bytes);
                 case VarType.Bit:
                     if (varCount == 1)
+                    {
                         if (bitAdr > 7)
                             return null;
                         else
                             return Types.Bit.FromByte(bytes[0], bitAdr);
+                    }
                     else
+                    {
                         return Types.Bit.ToBitArray(bytes);
+                    }
                 default:
                     return null;
             }
         }
 
         /// <summary>
-        /// Given a S7 variable type (Bool, Word, DWord, etc.), it returns how many bytes to read.
+        /// 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></returns>
+        /// <returns>Byte lenght of variable</returns>
         private int VarTypeToByteLength(VarType varType, int varCount = 1)
         {
             switch (varType)
@@ -1274,7 +1292,7 @@ namespace S7.Net
         #region IDisposable members
 
         /// <summary>
-        /// Releases all resources, disonnects from the plc and closes the socket
+        /// Releases all resources, disonnects from the PLC and closes the <see cref="Socket"/>
         /// </summary>
         public void Dispose()
         {