From ddfedaa17e72905068f742127d93289a03e294a0 Mon Sep 17 00:00:00 2001
From: Raphael <rs@sltgmbh.com>
Date: Fri, 8 Jun 2018 10:22:42 +0200
Subject: [PATCH 1/2] Typo in Exception string

---
 S7.Net/PLCHelpers.cs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/S7.Net/PLCHelpers.cs b/S7.Net/PLCHelpers.cs
index 7525ff2..ab59d2c 100644
--- a/S7.Net/PLCHelpers.cs
+++ b/S7.Net/PLCHelpers.cs
@@ -154,7 +154,7 @@ namespace S7.Net
                             varType = VarType.Counter;
                             return;
                         default:
-                            throw new InvalidAddressException(string.Format("{0} is not av valid address", address.Substring(0, 1)));
+                            throw new InvalidAddressException(string.Format("{0} is not a valid address", address.Substring(0, 1)));
                     }
 
                     string txt2 = address.Substring(1);
@@ -248,7 +248,7 @@ namespace S7.Net
         /// <returns></returns>
         private object ParseBytes(VarType varType, byte[] bytes, int varCount, byte bitAdr = 0)
         {
-            if (bytes == null)
+            if (bytes == null || bytes.Length == 0)
                 return null;
 
             switch (varType)
@@ -352,10 +352,10 @@ namespace S7.Net
         }
 
 
-    /// <summary>
-    /// Sets the <see cref="LastErrorCode"/> to <see cref="ErrorCode.NoError"/> and <see cref="LastErrorString"/> to <see cref="string.Empty"/>.
-    /// </summary>
-    public void ClearLastError()
+        /// <summary>
+        /// Sets the <see cref="LastErrorCode"/> to <see cref="ErrorCode.NoError"/> and <see cref="LastErrorString"/> to <see cref="string.Empty"/>.
+        /// </summary>
+        public void ClearLastError()
         {
             LastErrorCode = ErrorCode.NoError;
             LastErrorString = string.Empty;

From 1b22badea1440d8e251483abd0cf2ac89b9bb3c9 Mon Sep 17 00:00:00 2001
From: Raphael <rs@sltgmbh.com>
Date: Fri, 8 Jun 2018 10:26:52 +0200
Subject: [PATCH 2/2] Fixed ErrorCode.ReadData for specific methods

---
 S7.Net.UnitTest/S7NetTestsSync.cs | 15 +++++++++++++++
 S7.Net/PlcAsynchronous.cs         |  4 ++--
 S7.Net/PlcSynchronous.cs          | 13 +++++++------
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/S7.Net.UnitTest/S7NetTestsSync.cs b/S7.Net.UnitTest/S7NetTestsSync.cs
index 5948171..6daa9f7 100644
--- a/S7.Net.UnitTest/S7NetTestsSync.cs
+++ b/S7.Net.UnitTest/S7NetTestsSync.cs
@@ -897,6 +897,21 @@ namespace S7.Net.UnitTest
             Assert.AreEqual(tc.Bool1, tc2.Bool1);
         }
 
+        [TestMethod]
+        public void T29_Read_Write_ExceptionHandlingWhenPlcIsNotReachable()
+        {
+            // leave plc Open
+            S7TestServer.Stop();
+
+            double test_value = 55.66;
+            plc.Write("DB1.DBD0", test_value);
+            Assert.AreEqual(plc.LastErrorCode, ErrorCode.WriteData, "No Write Error.");
+
+            var helper = plc.Read("DB1.DBD0");
+            Assert.AreEqual(helper, null, "Value in Read.");
+            Assert.AreEqual(plc.LastErrorCode, ErrorCode.ReadData, "No Read Error.");
+        }
+
         #endregion
 
         #region Private methods
diff --git a/S7.Net/PlcAsynchronous.cs b/S7.Net/PlcAsynchronous.cs
index efaab86..ec5d18a 100644
--- a/S7.Net/PlcAsynchronous.cs
+++ b/S7.Net/PlcAsynchronous.cs
@@ -234,12 +234,12 @@ namespace S7.Net
             }
             catch (SocketException socketException)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = socketException.Message;
             }
             catch (Exception exc)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = exc.Message;
             }
             return dataItems;
diff --git a/S7.Net/PlcSynchronous.cs b/S7.Net/PlcSynchronous.cs
index b0ddcbd..892d58b 100644
--- a/S7.Net/PlcSynchronous.cs
+++ b/S7.Net/PlcSynchronous.cs
@@ -272,7 +272,8 @@ namespace S7.Net
             ErrorCode lastError = WriteBitWithASingleRequest(dataType, db, startByteAdr, bitAdr, value);
             if (lastError != ErrorCode.NoError)
             {
-                return lastError;            }
+                return lastError;
+            }
 
             return ErrorCode.NoError;
         }
@@ -388,13 +389,13 @@ namespace S7.Net
             }
             catch (SocketException socketException)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = socketException.Message;
                 return null;
             }
             catch (Exception exc)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = exc.Message;
                 return null;
             }
@@ -525,7 +526,7 @@ namespace S7.Net
                 {
                     package.Add(CreateReadDataRequestPackage(dataItem.DataType, dataItem.DB, dataItem.StartByteAdr, VarTypeToByteLength(dataItem.VarType, dataItem.Count)));
                 }
-                
+
                 stream.Write(package.Array, 0, package.Array.Length);
 
                 var s7data = COTP.TSDU.Read(stream); //TODO use Async
@@ -536,12 +537,12 @@ namespace S7.Net
             }
             catch (SocketException socketException)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = socketException.Message;
             }
             catch (Exception exc)
             {
-                LastErrorCode = ErrorCode.WriteData;
+                LastErrorCode = ErrorCode.ReadData;
                 LastErrorString = exc.Message;
             }
         }