diff --git a/TestBenchFramework/BenchControl/Keithley/Multimeter_2010_RS232/Multimeter.cs b/TestBenchFramework/BenchControl/Keithley/Multimeter_2010_RS232/Multimeter.cs
index 7cf80a64d..476a07923 100644
--- a/TestBenchFramework/BenchControl/Keithley/Multimeter_2010_RS232/Multimeter.cs
+++ b/TestBenchFramework/BenchControl/Keithley/Multimeter_2010_RS232/Multimeter.cs
@@ -200,7 +200,7 @@ namespace TBF.BenchControl.Keithley.Multimeter_2010_RS232
         /// <summary>Run this device</summary>
         public void RunDeviceBefore()
         {
-			if (multimeterCfg.DebugLevel == DebugMode.Simulate) return;
+			if (serialPort == null) return;
 
 			receivedData.Append(serialPort.ReadExisting());
 
@@ -244,7 +244,7 @@ namespace TBF.BenchControl.Keithley.Multimeter_2010_RS232
         /// <summary>Run this device</summary>
         public void RunDeviceAfter()
         {
-			if (multimeterCfg.DebugLevel == DebugMode.Simulate) return;
+            if (serialPort == null) return;
 
 			switch (scanState)
 			{
@@ -297,7 +297,11 @@ namespace TBF.BenchControl.Keithley.Multimeter_2010_RS232
         {
 			if (multimeterCfg.DebugLevel == DebugMode.Simulate) return;
 
-			serialPort.Close();
+            if (serialPort != null)
+            {
+                serialPort.Close();
+                serialPort = null;
+            }
 		}
 	}
 }
diff --git a/TestBenchFramework/Properties/AssemblyInfo.cs b/TestBenchFramework/Properties/AssemblyInfo.cs
index ec27560dd..7327e0901 100644
--- a/TestBenchFramework/Properties/AssemblyInfo.cs
+++ b/TestBenchFramework/Properties/AssemblyInfo.cs
@@ -29,5 +29,5 @@ using System.Runtime.InteropServices;
 //      Build Number
 //      Revision
 //
-[assembly: AssemblyVersion("2.12.535.1")]
-[assembly: AssemblyFileVersion("2.12.535.1")]
+[assembly: AssemblyVersion("2.12.536.1")]
+[assembly: AssemblyFileVersion("2.12.536.1")]