diff --git a/TBF/Rig/RegisterReaders/SerialStream/SerialStream.cs b/TBF/Rig/RegisterReaders/SerialStream/SerialStream.cs
index 8d4a695e5..bfc61cc9f 100644
--- a/TBF/Rig/RegisterReaders/SerialStream/SerialStream.cs
+++ b/TBF/Rig/RegisterReaders/SerialStream/SerialStream.cs
@@ -4,6 +4,7 @@
 using System;
 using System.IO;
 using System.IO.Ports;
+using System.Windows.Forms;
 using log4net;
 using Config.Entities;
 using TBF.Rig.Generic;
@@ -171,7 +172,8 @@ namespace TBF.Rig.RegisterReaders.SerialStream
         ///
         /// Opto serial port and worker thread related private variables
         ///
-        private SerialPort serialPort;
+        private SerialPort serialPort;      /// Used in DebugMode.Normal
+        private TextReader textReader;      /// Used instead of serialPort in DebugMode.Simulate
 
 
 		public SerialStream()
@@ -201,27 +203,27 @@ namespace TBF.Rig.RegisterReaders.SerialStream
         {
 			ClearData();
 
-			if (DebugLevel == DebugMode.Normal)
+            datastreamParsingEnabled = false;
+            currentFrameFormat = new FrameFormat(FrameLength, FrameFrequency,
+                                                 VolumeUnits, VolumeScaleFactor,
+                                                 VolumeFieldStart, VolumeFieldEnd, VolumeFieldFormat,
+                                                 TimeUnits, TimeScaleFactor,
+                                                 TimeFieldStart, TimeFieldEnd, TimeFieldFormat);
+            log.WarnFormat("Initialize() ... FrameFormat set to {0}", currentFrameFormat);
+
+            /// Allocate memory for opto-data from iPerl
+            datastreamFrames = new DatastreamFrame[MaxDatastreamFramesCount];
+            for (int i = 0; i < MaxDatastreamFramesCount; i++) datastreamFrames[i] = new DatastreamFrame();
+
+            toBeFlushed = new DatastreamFrame();
+            flushedFramesCount = 0;
+
+            synchronized = false;
+            synchronized2 = false;
+            partOfTelegram = string.Empty;
+
+            if (DebugLevel == DebugMode.Normal)
             {
-				datastreamParsingEnabled = false;
-                currentFrameFormat = new FrameFormat(FrameLength, FrameFrequency,
-                                                     VolumeUnits, VolumeScaleFactor,
-                                                     VolumeFieldStart, VolumeFieldEnd, VolumeFieldFormat,
-                                                     TimeUnits, TimeScaleFactor,
-                                                     TimeFieldStart, TimeFieldEnd, TimeFieldFormat);
-                log.WarnFormat("Initialize() ... FrameFormat set to {0}", currentFrameFormat);
-
-                /// Allocate memory for opto-data from iPerl
-				datastreamFrames = new DatastreamFrame[MaxDatastreamFramesCount];
-                for (int i = 0; i < MaxDatastreamFramesCount; i++) datastreamFrames[i] = new DatastreamFrame();
-
-				toBeFlushed = new DatastreamFrame();
-				flushedFramesCount = 0;
-
-				synchronized = false;
-				synchronized2 = false;
-				partOfTelegram = string.Empty;
-
                 /// Prepare serial port
                 serialPort = new SerialPort(string.Format("COM{0}", myCfg.ComPortNr),
                                             myCfg.BaudRate,
@@ -232,11 +234,22 @@ namespace TBF.Rig.RegisterReaders.SerialStream
 
 				serialPort.Open();
             }
+            else if (DebugLevel == DebugMode.Simulate)
+            {
+                try
+                {
+                    textReader = new StreamReader("C:\\TBF\\Simulate\\serialstream.txt");
+                }
+                catch (Exception)
+                {
+                    MessageBox.Show("Missing file C:\\TBF\\Simulate\\seriastream.txt");
+                }
+            }
         }
 
         public void RunDeviceBefore()
         {
-			if (DebugLevel == DebugMode.Normal)
+			if (DebugLevel == DebugMode.Normal || DebugLevel == DebugMode.Simulate)
 			{
 				try
 				{
@@ -462,13 +475,23 @@ namespace TBF.Rig.RegisterReaders.SerialStream
 		/// <param name="streamState">OptoState.Read or OptoState.Flush</param>
 		void ReadDatastream(DatastreamState streamState, FrameFormat ff)
 		{
-			int nrBytes = serialPort.BytesToRead;
-			if (nrBytes > 0)
-			{
-				char[] buffer = new char[nrBytes];
-				serialPort.Read(buffer, 0, nrBytes);
-				string received = new string(buffer);
+            string received = null;
 
+            if (DebugLevel == DebugMode.Normal)
+            {
+                int nrBytes = serialPort.BytesToRead;
+                char[] buffer = new char[nrBytes];
+                serialPort.Read(buffer, 0, nrBytes);
+                received = new string(buffer);
+            }
+            else if (DebugLevel == DebugMode.Simulate)
+            {
+                string line = textReader.ReadLine();
+                received = line + '\r' + '\n';
+            }
+
+            if (received != null)
+			{
 				string allRcvd = partOfTelegram + received;
 
 				while (true)