Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -rac305d5eedc7fb0e85adef5cd4aa34e58e94e3b8 -r7d4711edd7b40cd3e29f43e766f79a8a09586fe9
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision ac305d5eedc7fb0e85adef5cd4aa34e58e94e3b8)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 7d4711edd7b40cd3e29f43e766f79a8a09586fe9)
@@ -1,14 +1,14 @@
 /**************************************************************************
 *
-* Copyright (c) 2019-2023 Diality Inc. - All Rights Reserved.
+* Copyright (c) 2019-2024 Diality Inc. - All Rights Reserved.
 *
 * THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 * WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 *
 * @file    SystemComm.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      20-May-2023
+* @author  (last)      Sean Nash
+* @date    (last)      05-Oct-2023
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  05-Nov-2019
@@ -21,14 +21,15 @@
 #include "sci.h"
 #include "sys_dma.h"
 
-#include "DrainPump.h"
-#include "SystemComm.h"
 #include "Comm.h"
+#include "DrainPump.h"
+#include "Heaters.h"
 #include "Interrupts.h"
 #include "OperationModes.h"
+#include "SystemComm.h"
+#include "SystemCommMessages.h"
 #include "Timers.h"
 #include "Utilities.h"
-#include "SystemCommMessages.h"
 
 /**
  *  @addtogroup SystemComm
@@ -56,6 +57,9 @@
 #define MAX_FPGA_CLOCK_SPEED_ERRORS             3                           ///< maximum number of FPGA clock speed errors within window period before alarm
 #define MAX_FPGA_CLOCK_SPEED_ERROR_WINDOW_MS    (10 * SEC_PER_MIN * MS_PER_SECOND)    ///< FPGA clock speed error window
 
+#define PENDING_ACK_LIST_OVERRIDE_UI_CHANNEL    1                                     ///< Value for determining UI channel when Pending ACKs are overriden.
+#define PENDING_ACK_LIST_OVERRIDE_DG_CHANNEL    2                                     ///< Value for determining HD channel when Pending ACKs are overriden.
+
 #pragma pack(push, 1)
 
 /// Record for transmitted message that is pending acknowledgement from receiver.
@@ -106,6 +110,7 @@
 static U32 canXmitRetryCtr = 0;                                             ///< counter for CAN transmit retries.
 static OVERRIDE_U32_T hdCommunicationStatus = {0, 0, 0, 0};                 ///< has HD sent a message since last check
 static volatile U32 timeOfLastHDCheckIn = 0;                                ///< last time we received an HD broadcast
+static OVERRIDE_U32_T pendingACKOverride = { 0, 0, 0, 0 };                  ///< Pending ACK override data structure.
 
 // ********** private function prototypes **********
 
@@ -160,7 +165,7 @@
  *************************************************************************/
 BOOL isHDCommunicating( void )
 {
-    return getU32OverrideValue(&hdCommunicationStatus);
+    return getU32OverrideValue( &hdCommunicationStatus );
 }
 
 /*********************************************************************//**
@@ -668,6 +673,8 @@
     if ( TRUE == didTimeout( timeOfLastHDCheckIn, HD_COMM_TIMEOUT_IN_MS ) )
     {
         hdCommunicationStatus.data = FALSE;
+        setHDOperationMode( 0, 0 );      // If HD off or not connected, consider HD mode is fault.
+        stopHeater( DG_TRIMMER_HEATER ); // If HD off or not connected, ensure trimmer heater is off.
     }
 }
 
@@ -748,13 +755,18 @@
     BOOL result = FALSE;
     U32  i;
 
-    // find match
+    // Find match
     for ( i = 0; i < PENDING_ACK_LIST_SIZE; i++ )
     {
         if ( ( TRUE == pendingAckList[ i ].used ) && ( pendingAckList[ i ].seqNo == seqNo ) )
-        {   // remove message pending ACK from list
-            pendingAckList[ i ].used = FALSE;
+        {
             result = TRUE;
+            // Remove message pending ACK from list
+            if ( ( ( getU32OverrideValue( &pendingACKOverride ) != PENDING_ACK_LIST_OVERRIDE_UI_CHANNEL ) || ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_DG_2_UI ) ) &&
+                 ( ( getU32OverrideValue( &pendingACKOverride ) != PENDING_ACK_LIST_OVERRIDE_DG_CHANNEL ) || ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_DG_2_HD ) ) )
+            {
+                pendingAckList[ i ].used = FALSE;
+            }
             break;
         }
     }
@@ -881,6 +893,10 @@
             handleHDStartStopTrimmerHeaterCmd( message );
             break;
 
+        case MSG_ID_DG_PARK_CONCENTRATE_PUMPS_CMD_REQUEST:
+            handleParkConecentratePumpsCmd( message );
+            break;
+
         case MSG_ID_DG_START_STOP_TRIMMER_HEATER_CMD:
             handleDGStartStopTrimmerHeater( message );
             break;
@@ -1028,7 +1044,7 @@
                 handleTestValveStateOverrideRequest( message );
                 break;
 
-            case MSG_ID_VALVES_STATES_PUBLISH_INTERVAL_OVERRIDE:
+            case MSG_ID_DG_VALVES_STATES_PUBLISH_INTERVAL_OVERRIDE:
                 handleTestValvesStatesPublishIntervalOverrideRequest( message );
                 break;
 
@@ -1356,6 +1372,38 @@
                 handleTestDGSetRecoverFromFaultModeSignal( message );
                 break;
 
+            case MSG_ID_DG_DRAIN_MODE_BROADCAST_INTERVAL_OVERRIDE:
+                handleTestDGDrainModeBroadcastOverrideRequest( message );
+                break;
+
+            case MSG_ID_DG_DIALIN_RO_ONLY_MODE_STATUS_REQUEST:
+                handleDGROStatusRequest( message );
+                break;
+
+            case MSG_ID_DG_RAM_STATUS_OVERRIDE:
+                handleTestDGRAMStatusOverrideRequest( message );
+                break;
+
+            case MSG_ID_DG_RESERVOIR_BROADCAST_INTERVAL_OVERRIDE:
+                handleTestDGReservoirOverrideRequest( message );
+                break;
+
+            case MSG_ID_DG_CAN_RECEIVE_ACK_MESSAGE_OVERRIDE:
+                handleTestDGPendingACKOverrideRequest( message );
+                break;
+
+            case MSG_ID_DG_STATE_TIMER_82C_OVERRIDE:
+                handleTestDG82CStateTimerOverride( message );
+                break;
+
+            case MSG_ID_DG_STATE_TIMER_77C_OVERRIDE:
+                handleTestDG77CStateTimerOverride( message );
+                break;
+
+            case MSG_ID_DG_CHEM_DISINFECT_ACID_OVERRIDE:
+                handleTestChemDisinfectAcidOverride( message );
+                break;
+
             default:
                 // TODO - unrecognized message ID received - ignore
                 break;
@@ -1413,4 +1461,48 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The testSetPendingACKOverride function overrides the
+ * pendingACKOverride variable.
+ * @details Inputs: none
+ * @details Outputs: pendingACKOverride
+ * @param value override for pendingACKOverride
+ * @return TRUE if override successful, FALSE if not
+ *************************************************************************/
+BOOL testSetPendingACKOverride( U32 value )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        result = TRUE;
+        pendingACKOverride.ovData = value;
+        pendingACKOverride.override = OVERRIDE_KEY;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The testResetPendingACKOverride function resets the override
+ * of the pendingACKOverride variable.
+ * @details Inputs: none
+ * @details Outputs: pendingACKOverride
+ * @return TRUE if override reset successful, FALSE if not
+ *************************************************************************/
+BOOL testResetPendingACKOverride( void )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        result = TRUE;
+        pendingACKOverride.override = OVERRIDE_RESET;
+        pendingACKOverride.ovData = pendingACKOverride.ovInitData;
+    }
+
+    return result;
+}
 /**@}*/