Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -r85bfe5051e4d2bf67be39d394f96c075b4e52836 -r6311eb9b65fdeec7a285d25e07f3932ac0fb6cf1
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 85bfe5051e4d2bf67be39d394f96c075b4e52836)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 6311eb9b65fdeec7a285d25e07f3932ac0fb6cf1)
@@ -78,7 +78,6 @@
 
 static U32 sentCANPacketsCount = 0;  // TODO - debug - remove these two flags later
 static U32 compCANPacketsCount = 0;
-static CAN_MESSAGE_BOX_T pendingXmitMsgBox = 0;
 
 // ********** private function prototypes **********
 
@@ -251,22 +250,24 @@
  *************************************************************************/
 void handleCANMsgInterrupt( CAN_MESSAGE_BOX_T srcCANBox )
 {
-    if ( ( TRUE == isCANBoxForXmit( srcCANBox ) ) && ( srcCANBox != pendingXmitMsgBox ) )
-    {
-        srcCANBox = (CAN_MESSAGE_BOX_T)0;
-    }
-
     // message interrupt is for a transmit message box?
     if ( TRUE == isCANBoxForXmit( srcCANBox ) )
     {
         U32 bytesXmitted;
 
         compCANPacketsCount++;
-        bytesXmitted = transmitNextCANPacket();
-        if ( 0 == bytesXmitted )
+        if ( FALSE == canIsTxMessagePending( canREG1, srcCANBox ) )
         {
-            signalCANXmitsCompleted();
+            bytesXmitted = transmitNextCANPacket();
+            if ( 0 == bytesXmitted )
+            {
+                signalCANXmitsCompleted();
+            }
         }
+        else
+        {
+            compCANPacketsCount--;
+        }
     }
     else if ( TRUE == isCANBoxForRecv( srcCANBox ) )
     {
@@ -506,8 +507,7 @@
         if ( dataSize == CAN_MESSAGE_PAYLOAD_SIZE )
         {
             signalCANXmitsInitiated();
-            pendingXmitMsgBox = mBox;
-            if ( canTransmit( canREG1, mBox, data ) == 0 )
+            if ( 0 == canTransmit( canREG1, mBox, data ) )
             {
                 signalCANXmitsCompleted();
                 // TODO - shouldn't get here, but let's see if we do
@@ -516,8 +516,8 @@
             else
             {
                 sentCANPacketsCount++;
+                result = CAN_MESSAGE_PAYLOAD_SIZE;
             }
-            result = CAN_MESSAGE_PAYLOAD_SIZE;
         }
         else
         {   // TODO - shouldn't get here - just testing - set first data to new s/w fault enum later