Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -rfc7328b2b8158c88e11a063204d7e87519f472ca -rcd5be724d5a3ba7457e761191d82f278654d7f5c
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision fc7328b2b8158c88e11a063204d7e87519f472ca)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision cd5be724d5a3ba7457e761191d82f278654d7f5c)
@@ -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)      Sean Nash
-* @date    (last)      07-Jul-2023
+* @date    (last)      10-Oct-2023
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  05-Nov-2019
@@ -60,6 +60,9 @@
 #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 DG channel when Pending ACKs are overriden.
+
 #pragma pack(push, 1)
 
 /// Record for transmitted message that is pending acknowledgment from receiver.
@@ -112,7 +115,8 @@
 static U32 timeOfLastDGCheckIn = 0;                                         ///< Last time DG checked in
 static volatile BOOL uiIsCommunicating = FALSE;                             ///< Has UI sent a message since last check
 static U32 timeOfLastUICheckIn = 0;                                         ///< Last time UI checked in
-static volatile BOOL uiDidCommunicate = FALSE;                              ///< Has UI every sent a message
+static volatile BOOL uiDidCommunicate = FALSE;                              ///< Has UI every sent a message
+static OVERRIDE_U32_T pendingACKOverride = { 0, 0, 0, 0 };                  ///< Pending ACK override data structure.
 
 // ********** private function prototypes **********
 
@@ -875,15 +879,20 @@
 static BOOL matchACKtoPendingACKList( S16 seqNo )
 {
     BOOL result = FALSE;
-    U32  i;
+    U32  i;
 
     // 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;
+        {
+            result = TRUE;
+            // Remove message pending ACK from list
+            if ( ( ( getU32OverrideValue( &pendingACKOverride ) != PENDING_ACK_LIST_OVERRIDE_UI_CHANNEL ) || ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_UI ) ) &&
+                 ( ( getU32OverrideValue( &pendingACKOverride ) != PENDING_ACK_LIST_OVERRIDE_DG_CHANNEL ) || ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_DG ) ) )
+            {
+                pendingAckList[ i ].used = FALSE;
+            }
             break;
         }
     }
@@ -921,6 +930,7 @@
                 U16 msgID;
 
                 memcpy( &msgID, (U08*)&pendingAckList[ i ].msg[ sizeof( U08 ) + sizeof( U16) ], sizeof( U16 ) );
+
                 if ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_DG )
                 {
                     SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED_BY_UI, (U32)msgID );
@@ -1210,7 +1220,7 @@
     }
 
     // Handle any test messages if tester has logged in successfully
-    if ( ( msgID > MSG_ID_FIRST_TESTER_MESSAGE ) && ( msgID <= END_OF_MSG_IDS ) && ( TRUE == isTestingActivated() ) )
+    if ( ( msgID > MSG_ID_FIRST_TESTER_MESSAGE ) && ( TRUE == isTestingActivated() ) )
     {
         switch ( msgID )
         {
@@ -1374,7 +1384,7 @@
                 handleTestSetTreatmentParameter( message );
                 break;
 
-            case MSG_ID_VALVES_STATES_PUBLISH_INTERVAL_OVERRIDE:
+            case MSG_ID_HD_VALVES_STATES_PUBLISH_INTERVAL_OVERRIDE:
                 handleTestHDValvesBroadcastIntervalOverrideRequest( message );
                 break;
 
@@ -1794,6 +1804,18 @@
                 handleTestHDSetRecoverFromFaultModeSignal( message );
                 break;
 
+            case MSG_ID_HD_RAM_STATUS_OVERRIDE:
+                handleTestHDRAMStatusOverrideRequest( message );
+                break;
+
+            case MSG_ID_HD_CAN_RECEIVE_ACK_MESSAGE_OVERRIDE:
+                handleTestHDPendingACKOverrideRequest( message );
+                break;
+
+            case MSG_ID_HD_RECIRULATION_PCT_OVERRIDE:
+                handleTestHDRecirulationPctOverrideRequest( message );
+                break;
+
             // The default cannot be reached in VectorCAST since the cases are run in a for loop
             default:
                 // Unrecognized message ID received - ignore
@@ -1802,4 +1824,54 @@
     }
 }
 
+
+/*************************************************************************
+ *                       TEST SUPPORT FUNCTIONS
+ *************************************************************************/
+
+
+/*********************************************************************//**
+ * @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;
+}
 /**@}*/