Index: firmware/App/Services/CommBuffers.c
===================================================================
diff -u -r3f3729899d6811c763bc8e5ef9baf54a2d5c9cfe -r8f5feed92f41a476d5656038bcdfe884e17bd593
--- firmware/App/Services/CommBuffers.c	(.../CommBuffers.c)	(revision 3f3729899d6811c763bc8e5ef9baf54a2d5c9cfe)
+++ firmware/App/Services/CommBuffers.c	(.../CommBuffers.c)	(revision 8f5feed92f41a476d5656038bcdfe884e17bd593)
@@ -17,7 +17,8 @@
 
 #include <string.h>     // for memcpy()
 
-#include "CommBuffers.h"
+#include "CommBuffers.h"
+#include "SystemComm.h"
 #include "SystemCommMessages.h"
 #include "Timers.h"
 
@@ -118,34 +119,40 @@
     {
         BOOL bufferFull = FALSE;
         U32 activeBuffer;
-        U32 currentActiveBufCount;  // where to start adding new data to buffer (after existing data)
+        U32 currentActiveBufCount;  // where to start adding new data to buffer (after existing data)
+
+        // prevent adding to out-going CAN buffer if DG is only node on CAN bus
+        if ( ( FALSE == isDGOnlyCANNode() ) ||
+             ( FALSE == isCANBoxForXmit( (CAN_MESSAGE_BOX_T)buffer ) ) )
+        {
+            // thread protection for queue operations
+            _disable_IRQ();
 
-        // thread protection for queue operations
-        _disable_IRQ();
+            activeBuffer = activeDoubleBuffer[ buffer ];
+            currentActiveBufCount = commBufferByteCount[ buffer ][ activeBuffer ];
 
-        activeBuffer = activeDoubleBuffer[ buffer ];
-        currentActiveBufCount = commBufferByteCount[ buffer ][ activeBuffer ];
+            // check to make sure buffer is not too full to service this add
+            if ( len <= ( COMM_BUFFER_LENGTH - currentActiveBufCount ) )
+            {
+                U08 *buffPtr;  // buffer destination for added data
 
-        // check to make sure buffer is not too full to service this add
-        if ( len <= ( COMM_BUFFER_LENGTH - currentActiveBufCount ) )
-        {
-            U08 *buffPtr;  // buffer destination for added data
+                // set destination pointer to end of active buffer data
+                buffPtr = &commBuffers[ buffer ][ activeBuffer ][ currentActiveBufCount ];
+                // copy source data to destination buffer
+                memcpy( buffPtr, data, len );
+                // adjust buffer count per this data add (also reserves space to add data before releasing thread protection)
+                commBufferByteCount[ buffer ][ activeBuffer ] += len;
+                // data successfully added to buffer
+                result = TRUE;
+            }
+            else // buffer too full to add this much data
+            {
+                bufferFull = TRUE;
+            }
+            // release thread protection
+            _enable_IRQ();
+        }
 
-            // set destination pointer to end of active buffer data
-            buffPtr = &commBuffers[ buffer ][ activeBuffer ][ currentActiveBufCount ];
-            // copy source data to destination buffer
-            memcpy( buffPtr, data, len );
-            // adjust buffer count per this data add (also reserves space to add data before releasing thread protection)
-            commBufferByteCount[ buffer ][ activeBuffer ] += len;
-            // data successfully added to buffer
-            result = TRUE;
-        }
-        else // buffer too full to add this much data
-        {
-            bufferFull = TRUE;
-        }
-        // release thread protection
-        _enable_IRQ();
         // if buffer was full, check persistence - trigger s/w fault if persists
         if ( TRUE == bufferFull )
         {
@@ -162,7 +169,7 @@
                 // if buffer overflows persists, fault
                 if ( calcTimeSince( firstBufferOverflowTimeStamp ) > BUFFER_OVERFLOW_PERSISTENCE_MS )
                 {
-                    SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_ADD_TOO_MUCH_DATA, len )
+                    SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_ADD_TOO_MUCH_DATA, (U32)buffer )
                 }
             }
             else // first overflow - set time stamp for persistence check
@@ -180,7 +187,7 @@
     }
     else // invalid buffer given
     {
-        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_ADD_INVALID_BUFFER, buffer )
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_ADD_INVALID_BUFFER, buffer )
     }
 
     return result;
@@ -241,7 +248,7 @@
     }
     else // invalid buffer given
     {
-        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_GET_INVALID_BUFFER, buffer )
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_GET_INVALID_BUFFER, buffer )
     }
 
     return result;
@@ -299,7 +306,7 @@
     }
     else // invalid buffer given
     {
-        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_PEEK_INVALID_BUFFER, buffer )
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_PEEK_INVALID_BUFFER, buffer )
     }
 
     return numOfBytesPeeked;
@@ -330,7 +337,7 @@
     }
     else // invalid buffer
     {
-        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_COUNT_INVALID_BUFFER, buffer )
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DG_SOFTWARE_FAULT, SW_FAULT_ID_COMM_BUFFERS_COUNT_INVALID_BUFFER, buffer )
     }
 
     return result;