Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r9df8618dfd95d3af354e6cbb590ebe6f6fd7ccdd -r6e07046677cba738be6f78b155f4f23120a43081
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 9df8618dfd95d3af354e6cbb590ebe6f6fd7ccdd)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 6e07046677cba738be6f78b155f4f23120a43081)
@@ -14,8 +14,9 @@
 * @date (original) 08-Apr-2020
 *
 ***************************************************************************/
-
+
 #include "DialInFlow.h"
+#include "DGDefs.h"
 #include "ModeTreatment.h"
 #include "OperationModes.h"
 #include "SystemCommMessages.h"
@@ -105,6 +106,9 @@
 static U32 dgReservoirDrainVolumeTargetSet = 0;                 ///< Drain-to volume commanded.
 static U32 resUseTimer = 0;                                     ///< Used to track time pumping from active reservoir (for volume used calculation).
 static F32 resUseVolumeMl = 0.0;                                ///< Accumulated volume used from active reservoir.
+
+// DG command response
+static DG_CMD_RESPONSE_T dgCmdResp;                             ///< Used to keep the latest DG command response.
 
 // ********** private function prototypes **********
 
@@ -151,6 +155,11 @@
             lgLoadCellReadings[ i ][ j ] = 0.0;
         }
     }
+
+    dgCmdResp.commandID = DG_CMD_NONE;
+    dgCmdResp.rejected  = TRUE;
+    dgCmdResp.rejectCode = DG_CMD_REQUEST_REJECT_REASON_NONE;
+
     smLoadCellReadingsIdx = 0;
     smLoadCellReadingsTotal[ DG_RESERVOIR_1 ] = 0.0;
     smLoadCellReadingsTotal[ DG_RESERVOIR_2 ] = 0.0;
@@ -735,7 +744,8 @@
  *************************************************************************/
 void cmdStartDGTrimmerHeater( void )
 {
-    dgTrimmerHeaterOn = TRUE;
+    dgTrimmerHeaterOn = TRUE;
+    dgCmdResp.commandID = DG_CMD_NONE;
     sendDGStartStopTrimmerHeaterCommand( START_DG_CMD );
 }
 
@@ -749,7 +759,8 @@
  *************************************************************************/
 void cmdStopDGTrimmerHeater( void )
 {
-    dgTrimmerHeaterOn = FALSE;
+    dgTrimmerHeaterOn = FALSE;
+    dgCmdResp.commandID = DG_CMD_NONE;
     sendDGStartStopTrimmerHeaterCommand( STOP_DG_CMD );
 }
 
@@ -766,7 +777,8 @@
 {
     if ( resID < NUM_OF_DG_RESERVOIRS )
     {
-        dgActiveReservoirSet = resID;
+        dgActiveReservoirSet = resID;
+        dgCmdResp.commandID = DG_CMD_NONE;
         sendDGSwitchReservoirCommand( (U32)resID );
     }
     else
@@ -784,7 +796,8 @@
  * @return none
  *************************************************************************/
 void cmdStartDGFill( U32 fillToVolMl )
-{
+{
+    dgCmdResp.commandID = DG_CMD_NONE;
     dgReservoirFillVolumeTargetSet = fillToVolMl;
     sendDGFillCommand( fillToVolMl );
 }
@@ -802,6 +815,7 @@
 {
     DRAIN_RESERVOIR_CMD_PAYLOAD_T payload;
 
+    dgCmdResp.commandID = DG_CMD_NONE;
     payload.drainToVolumeML = drainToVolMl;
     payload.tareLoadCells = tareLoadCell;
     dgReservoirDrainVolumeTargetSet = drainToVolMl;
@@ -821,7 +835,38 @@
     sendDGSampleWaterCommand();
 }
 
+/*********************************************************************//**
+ * @brief
+ * The handleDGCommandResponse function processes the latest DG command response.
+ * @details Inputs: none
+ * @details Outputs: process command response from DG
+ * @param cmdRespPtr pointer to DG command response data record
+ * @return none
+ *************************************************************************/
+void handleDGCommandResponse( U08 *cmdRespPtr )
+{
+    memcpy( &dgCmdResp, cmdRespPtr, sizeof( DG_CMD_RESPONSE_T ) );
 
+    if ( ( TRUE == dgCmdResp.rejected ) && ( DG_CMD_REQUEST_REJECT_REASON_INVALID_PARAMETER == dgCmdResp.rejectCode ) )
+    {
+        activateAlarmNoData( ALARM_ID_DG_COMMAND_INVALID_PARAMETER_FAULT );
+    }
+}
+
+/*********************************************************************//**
+ * @brief
+ * The getDGCommandResponse function gets the latest command response from DG.
+ * @details Inputs: dgCmdResp
+ * @details Outputs: none
+ * @param cmdRespPtr pointer to data record to copy DG command response to
+ * @return none
+ *************************************************************************/
+void getDGCommandResponse( DG_CMD_RESPONSE_T *cmdRespPtr )
+{
+    memcpy( &cmdRespPtr, &dgCmdResp, sizeof( DG_CMD_RESPONSE_T ) );
+}
+
+
 /*************************************************************************
  *                       TEST SUPPORT FUNCTIONS
  *************************************************************************/