Index: App/Services/SystemComm.c
===================================================================
diff -u -r6c8c486d26306662402945537c5acaea2709d85b -r447eb904c9deb9536c04c9cc0e009a0b26b55573
--- App/Services/SystemComm.c	(.../SystemComm.c)	(revision 6c8c486d26306662402945537c5acaea2709d85b)
+++ App/Services/SystemComm.c	(.../SystemComm.c)	(revision 447eb904c9deb9536c04c9cc0e009a0b26b55573)
@@ -141,7 +141,7 @@
     }
 
     // if UART transmitter is idle, start transmitting any pending packets
-//    if ( FALSE == isSCI1DMATransmitInProgress() )
+    if ( FALSE == isSCI1DMATransmitInProgress() )
     {
         transmitNextUARTPacket();
     }
@@ -278,7 +278,7 @@
     pcDMARecvControlRecord.FRDOFFSET = 0;                     // not used
     pcDMARecvControlRecord.FRSOFFSET = 0;                     // not used
 
-    // initiate UART packet receiving readiness via DMA
+    // initiate PC packet receiving readiness via DMA
     dmaSetCtrlPacket( DMA_CH1, pcDMARecvControlRecord );
     dmaSetChEnable( DMA_CH1, DMA_HW );
     setSCI1DMAReceiveInterrupt();
@@ -554,11 +554,12 @@
             U32 pos = i + 1;  // skip past sync byte implemented
             U32 remSize = len - pos;
 
-            // if a minimum sized msg would fit in remaining
+            // if a minimum sized msg would fit in remaining, continue
             if ( remSize >= MESSAGE_OVERHEAD_SIZE )
             {
                 cargoSize = data[pos+sizeof(U16)];
                 msgSize = MESSAGE_OVERHEAD_SIZE + cargoSize;
+                // we now know the size of the message - we can now know if full message is contained in buffer
                 if ( msgSize <= remSize )
                 {
                     result = msgSize; // we found a complete message of this size
@@ -646,6 +647,10 @@
     {
         switch ( msgID )
         {
+            case MSG_ID_HD_MESSAGE:
+                handleTestHDMessageRequest( message );
+                break;
+
             case MSG_ID_OFF_BUTTON_STATE_OVERRIDE:
                 handleTestOffButtonStateOverrideRequest( message );
                 break;