Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -r19f13e67288117e7f81c1245a75cc6b5f8aaf899 -r46b16ef94cea2d5db25bfee08457686bc440de23
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 19f13e67288117e7f81c1245a75cc6b5f8aaf899)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 46b16ef94cea2d5db25bfee08457686bc440de23)
@@ -7,8 +7,8 @@
 *
 * @file    SystemComm.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      20-Mar-2023
+* @author  (last)      James Walter Taylor
+* @date    (last)      31-Mar-2023
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  05-Nov-2019
@@ -45,15 +45,15 @@
 #define CAN_XMIT_PACKET_TIMEOUT_MS      200     ///< If transmitted CAN frame does not cause a transmit complete interrupt within this time, re-send or move on
 #define MAX_XMIT_RETRIES                5       ///< Maximum number of retries on no transmit complete interrupt timeout
 
-#define UI_COMM_TIMEOUT_IN_MS           5000    ///< UI has not checked in for this much time
+#define UI_COMM_TIMEOUT_IN_MS           7500    ///< UI has not checked in for this much time
 #define DG_COMM_TIMEOUT_IN_MS           1000    ///< DG has not checked in for this much time
 
 #define MAX_COMM_CRC_FAILURES           5       ///< Maximum number of CRC errors within window period before alarm
 #define MAX_COMM_CRC_FAILURE_WINDOW_MS  (10 * SEC_PER_MIN * MS_PER_SECOND)  ///< CRC error window
 
-#define MSG_NOT_ACKED_TIMEOUT_MS        150     ///< Maximum time for a Denali message that requires ACK to be ACK'd
+#define MSG_NOT_ACKED_TIMEOUT_MS        250     ///< Maximum time for a Denali message that requires ACK to be ACK'd
 
-#define MSG_NOT_ACKED_MAX_RETRIES       8       ///< Maximum number of times a message that requires ACK that was not ACK'd can be re-sent before alarm
+#define MSG_NOT_ACKED_MAX_RETRIES       10      ///< Maximum number of times a message that requires ACK that was not ACK'd can be re-sent before alarm
 #define PENDING_ACK_LIST_SIZE           25      ///< Maximum number of Denali messages that can be pending ACK at any given time
 
 #define MAX_FPGA_CLOCK_SPEED_ERRORS     3       ///< maximum number of FPGA clock speed errors within window period before alarm
@@ -533,7 +533,7 @@
  * Comm Buffers and adds them to the Received Message Queue.
  * @details Inputs: none
  * @details Outputs:hdIsOnlyCANNode, rcvMsg, dgIsCommunicating,
- * timeOfLastDGCheckIn
+ * timeOfLastDGCheckIn, timeOfLastUICheckIn, uiDidCommunicate
  * @return none
  *************************************************************************/
 static void processIncomingData( void )
@@ -592,6 +592,12 @@
                     {
                         dgIsCommunicating = TRUE;
                         timeOfLastDGCheckIn = getMSTimerCount();
+                    }
+                    // If message from UI channel, mark UI communication so HD can begin transmitting
+                    if ( ( COMM_BUFFER_IN_CAN_UI_2_HD == MSG_IN_BUFFERS[ i ] ) || ( COMM_BUFFER_IN_CAN_UI_BROADCAST == MSG_IN_BUFFERS[ i ] ) )
+                    {
+                        timeOfLastUICheckIn = getMSTimerCount();
+                        uiDidCommunicate = TRUE;
                     }
                 }
                 else if ( -1 == msgSize ) // Candidate message with bad CRC found?
@@ -900,7 +906,14 @@
                 U16 msgID;
 
                 memcpy( &msgID, (U08*)&pendingAckList[ i ].msg[ sizeof( U08 ) + sizeof( U16) ], sizeof( U16 ) );
-                SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED, (U32)msgID );
+                if ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_DG )
+                {
+                    SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED_UI, (U32)msgID );
+                }
+                else
+                {
+                    SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED_DG, (U32)msgID );
+                }
                 pendingAckList[ i ].used = FALSE;  // Take pending message off of list
             }
         }