Index: App/Services/CommInterrupts.c
===================================================================
diff -u -r6c8c486d26306662402945537c5acaea2709d85b -r447eb904c9deb9536c04c9cc0e009a0b26b55573
--- App/Services/CommInterrupts.c	(.../CommInterrupts.c)	(revision 6c8c486d26306662402945537c5acaea2709d85b)
+++ App/Services/CommInterrupts.c	(.../CommInterrupts.c)	(revision 447eb904c9deb9536c04c9cc0e009a0b26b55573)
@@ -25,6 +25,7 @@
 
 // ********** private definitions **********
 
+#define DMA_CH_STATUS_BIT(ch)       ((U32)1U << (ch))
 
 // ********** private data **********
 
@@ -250,9 +251,10 @@
  *************************************************************************/
 BOOL isSCI1DMATransmitInProgress( void )
 {
-    BOOL transmitterBusy = ( ( sciREG->FLR & (uint32)SCI_TX_INT ) == 0U ? TRUE : FALSE );
-    BOOL dmaTransmitterBusy = ( ( sciREG->CLEARINT & SCI_DMA_RECEIVE_INT ) != 0 ? TRUE : FALSE );
+    BOOL transmitterBusy = ( ( sciREG->FLR & (U32)SCI_TX_INT ) == 0U ? TRUE : FALSE );
+    BOOL dmaTransmitterBusy = ( ( dmaREG->PEND & DMA_CH_STATUS_BIT(DMA_CH3) ) != 0U ? TRUE : FALSE );
 
+
     return ( ( transmitterBusy == TRUE ) || ( dmaTransmitterBusy == TRUE ) ? TRUE : FALSE );
 }
 
@@ -268,8 +270,8 @@
  *************************************************************************/
 BOOL isSCI2DMATransmitInProgress( void )
 {
-    BOOL transmitterBusy = ( ( scilinREG->FLR & (uint32)SCI_TX_INT ) == 0U ? TRUE : FALSE );
-    BOOL dmaTransmitterBusy = ( ( scilinREG->CLEARINT & SCI_DMA_RECEIVE_INT ) != 0 ? TRUE : FALSE );
+    BOOL transmitterBusy = ( ( scilinREG->FLR & (U32)SCI_TX_INT ) == 0U ? TRUE : FALSE );
+    BOOL dmaTransmitterBusy = ( ( dmaREG->PEND & DMA_CH_STATUS_BIT(DMA_CH2) ) != 0U ? TRUE : FALSE );
 
     return ( ( transmitterBusy == TRUE ) || ( dmaTransmitterBusy == TRUE ) ? TRUE : FALSE );
 }
Index: App/Services/FPGA.c
===================================================================
diff -u -r8ca991f9c04d8d301ada71eabc297f514b0d6cf8 -r447eb904c9deb9536c04c9cc0e009a0b26b55573
--- App/Services/FPGA.c	(.../FPGA.c)	(revision 8ca991f9c04d8d301ada71eabc297f514b0d6cf8)
+++ App/Services/FPGA.c	(.../FPGA.c)	(revision 447eb904c9deb9536c04c9cc0e009a0b26b55573)
@@ -564,7 +564,7 @@
     FPGA_STATE_T result = FPGA_STATE_WRITE_ALL_ACTUATORS;
 
     // check bulk write command success
-    if ( ( FALSE == fpgaWriteCommandResponseReceived ) || ( fpgaWriteResponseBuffer[0] != FPGA_WRITE_CMD_ACK )
+    if ( ( FALSE == fpgaWriteCommandResponseReceived ) || ( fpgaWriteResponseBuffer[0] != FPGA_WRITE_CMD_ACK ) )
     {
         // TODO - ???
     }
@@ -588,7 +588,6 @@
         // TODO - ???
     }
 
-
     return result;
 }
 
@@ -777,9 +776,7 @@
  *************************************************************************/
 U16 getFPGAStatus( void )
 {
-    U16 result = MAKE_WORD_OF_BYTES(fpgaHeader.fpgaStatusHigh,fpgaHeader.fpgaStatusLow);
-
-    return result;
+    return fpgaHeader.fpgaStatus;
 }
 
 /*************************************************************************
@@ -794,7 +791,6 @@
  *************************************************************************/
 void setFPGAControl( U16 ctrl )
 {
-    fpgaHeader.fpgaControlHigh = GET_MSB_OF_WORD( ctrl );
-    fpgaHeader.fpgaControlLow = GET_MSB_OF_WORD( ctrl );
+    fpgaHeader.fpgaControl = ctrl;
 }
 
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;
Index: source/sys_main.c
===================================================================
diff -u -r38ff7a6fbf82b86ab1bac3b7b24c4ea33d5419f9 -r447eb904c9deb9536c04c9cc0e009a0b26b55573
--- source/sys_main.c	(.../sys_main.c)	(revision 38ff7a6fbf82b86ab1bac3b7b24c4ea33d5419f9)
+++ source/sys_main.c	(.../sys_main.c)	(revision 447eb904c9deb9536c04c9cc0e009a0b26b55573)
@@ -127,8 +127,6 @@
     canInit();      // CAN1 = CAN, re-purposing CAN2 and CAN3 Rx and Tx pins as GPIO
     sciInit();      // SCI1 used for PC serial interface, SCI2 used for FPGA serial interface
     dmaEnable();    // enable DMA
-//    sciEnableLoopback( sciREG, Digital_Lbk );  // TODO - for test only
-//    sciEnableLoopback( scilinREG, Digital_Lbk );  // TODO - for test only
 }
 
 /*************************************************************************