Index: firmware/App/Modes/OperationModes.c
===================================================================
diff -u -r8bd1ae47aa13a843aa8abd6321ddc050deacb4a6 -rc137d3c7cb17b0364d745e10ff6dbd1901eb1baa
--- firmware/App/Modes/OperationModes.c	(.../OperationModes.c)	(revision 8bd1ae47aa13a843aa8abd6321ddc050deacb4a6)
+++ firmware/App/Modes/OperationModes.c	(.../OperationModes.c)	(revision c137d3c7cb17b0364d745e10ff6dbd1901eb1baa)
@@ -49,6 +49,7 @@
 static U32 broadcastModeIntervalCtr = 11;                   ///< Interval counter used to determine when to broadcast operation mode.  Initialize to 11 to stagger broadcast.
 /// Interval (in task intervals) at which to publish operation mode data to CAN bus.
 static OVERRIDE_U32_T opModePublishInterval = { BROADCAST_HD_OP_MODE_INTERVAL, BROADCAST_HD_OP_MODE_INTERVAL, BROADCAST_HD_OP_MODE_INTERVAL, 0 };
+static U32 priorSubMode = 0;                                ///< The prior submode state.
 
 /// This matrix determines legal transitions from one mode to another
 static const HD_OP_MODE_T MODE_TRANSITION_TABLE[ NUM_OF_MODES - 1 ][ NUM_OF_MODES - 1 ] = {
@@ -88,6 +89,7 @@
     // Start in init mode
     currentMode = MODE_INIT;
     currentSubMode = 0;
+    priorSubMode = 0;
     transitionToNewOperationMode( MODE_INIT );
 
     // Call initializers for the individual modes
@@ -111,8 +113,9 @@
 void execOperationModes( void )
 {
     HD_OP_MODE_T newMode;
-    U32 priorSubMode = currentSubMode;
 
+    priorSubMode = currentSubMode;
+
     // Any new mode requests?
     newMode = arbitrateModeRequest();   // Will return current mode if no pending requests
     newMode = MODE_TRANSITION_TABLE[ currentMode ][ newMode ];
@@ -128,7 +131,6 @@
     if ( currentMode != newMode )
     {
         // Handle transition to new mode
-        priorSubMode = 0;
         lastMode = currentMode;
         transitionToNewOperationMode( newMode );
         currentMode = newMode;
@@ -332,33 +334,37 @@
     switch ( newMode )
     {
         case MODE_FAUL:
-            transitionToFaultMode();
+            currentSubMode = transitionToFaultMode();
             break;
         case MODE_SERV:
-            transitionToServiceMode();
+            currentSubMode = transitionToServiceMode();
             break;
         case MODE_INIT:
-            transitionToInitAndPOSTMode();
+            currentSubMode = transitionToInitAndPOSTMode();
             break;
         case MODE_STAN:
-            transitionToStandbyMode();
+            currentSubMode = transitionToStandbyMode();
             break;
         case MODE_TPAR:
-            transitionToTreatParamsMode();
+            currentSubMode = transitionToTreatParamsMode();
             break;
         case MODE_PRET:
-            transitionToPreTreatmentMode();
+            currentSubMode = transitionToPreTreatmentMode();
             break;
         case MODE_TREA:
-            transitionToTreatmentMode();
+            currentSubMode = transitionToTreatmentMode();
             break;
         case MODE_POST:
-            transitionToPostTreatmentMode();
+            currentSubMode = transitionToPostTreatmentMode();
             break;
         default:
             SET_ALARM_WITH_2_U32_DATA( ALARM_ID_HD_SOFTWARE_FAULT, SW_FAULT_ID_OP_MODES_INVALID_MODE_TO_TRANSITION_TO, newMode )
             break;
     }
+
+    SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_MODE_CHANGE, priorSubMode, currentSubMode )
+
+    priorSubMode = currentSubMode;
 }
 
 /*********************************************************************//**