Index: firmware/App/Modes/FPModes/FPOperationModes.c
===================================================================
diff -u -rd210786d6c7d75bb0b4d9e18efc40a01d85123fe -rcb8619fdf8690885708071d34b0e87e6657ecd62
--- firmware/App/Modes/FPModes/FPOperationModes.c	(.../FPOperationModes.c)	(revision d210786d6c7d75bb0b4d9e18efc40a01d85123fe)
+++ firmware/App/Modes/FPModes/FPOperationModes.c	(.../FPOperationModes.c)	(revision cb8619fdf8690885708071d34b0e87e6657ecd62)
@@ -47,6 +47,8 @@
 static U32 broadcastModeIntervalCtr;                                            ///< Interval counter used to determine when to broadcast operation mode.  Initialize to 11 to stagger broadcast.
 static U32 currentSubState;                                                     ///< current sub state.
 static U32 current4thLevelState;                                                ///< current 4th level state.
+static U32 requestedSubMode;                                                    ///< Requested operation sub mode.
+static BOOL changeSubMode;                                                      ///< Flag that change operation sub mode request status.
 static BOOL isDeviceDefeatured;                                                 ///< bool to determine defeatured status
 static BOOL isBoostInstalled;                                                   ///< bool to determine boost pump status
 
@@ -94,6 +96,8 @@
     currentSubMode           = 0;
     currentSubState          = NO_FP_SUB_STATE;
     current4thLevelState     = NO_FP_SUB_STATE;
+    requestedSubMode         = 0;
+    changeSubMode            = FALSE;
     broadcastModeIntervalCtr = DATA_PUBLISH_COUNTER_START_COUNT;
     isDeviceDefeatured       = FALSE;
     isBoostInstalled         = FALSE;
@@ -144,7 +148,37 @@
         currentMode = newMode;
 //        sendOperationStatusEvent();
     }
+    // Is sub mode change request active?
+    if ( changeSubMode )
+    {
+        switch ( currentMode )
+        {
+            case FP_MODE_PGEN:
+                signalNewPreGenPSubMode( requestedSubMode );
+                break;
 
+            case FP_MODE_GENP:
+                signalNewGenPermeateSubMode( requestedSubMode );
+                break;
+
+            case FP_MODE_DPGP:
+                signalNewPreGenPDefeaturedSubMode( requestedSubMode );
+                break;
+
+            case FP_MODE_DEGP:
+                signalNewGenPDefeaturedSubMode( requestedSubMode );
+                break;
+
+            case FP_MODE_FAUL:
+            case FP_MODE_SERV:
+            case FP_MODE_INIT:
+            case FP_MODE_STAN:
+            default:
+                break;
+        }
+        changeSubMode = FALSE;
+    }
+
     // Mode specific processing to be done continuously
     switch ( currentMode )
     {
@@ -226,6 +260,21 @@
 
 /*********************************************************************//**
  * @brief
+ * The requestNewFPOperationSubMode function requests transition to a new
+ * operation sub mode. The request will be arbitrated when the state machine
+ * is next executed.
+ * @details \b Inputs: none
+ * @details \b Outputs: requestedSubMode, changeSubMode
+ * @return none
+ *************************************************************************/
+void requestNewFPOperationSubMode( U32 reqSubMode )
+{
+    requestedSubMode = reqSubMode;
+    changeSubMode = TRUE;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getCurrentFPOperationMode function gets the current operation mode.
  * @details \b Inputs: currentMode
  * @details \b Outputs: none
@@ -529,6 +578,45 @@
 
 /*********************************************************************//**
  * @brief
+ * The testSetFPOperationSubMode function will transition to a given
+ * sub mode if the transition is legal.
+ * @details \b Inputs: none
+ * @details \b Outputs: request new sub mode function called for current Op mode
+ * @param message message from Dialin which includes the sub mode to
+ * transition to.
+ * @return TRUE if request successful, FALSE if not
+ *************************************************************************/
+BOOL testSetFPOperationSubMode( MESSAGE_T *message )
+{
+    OP_MODE_PAYLOAD_T payload;
+    BOOL result = FALSE;
+
+    // Verify message payload length is valid
+    if ( sizeof( OP_MODE_PAYLOAD_T ) == message->hdr.payloadLen )
+    {
+        memcpy( (U08*)(&payload), message->payload, sizeof( OP_MODE_PAYLOAD_T ) );
+
+        FP_OP_MODE_T reqMode = (FP_OP_MODE_T)payload.opMode;
+        U32 reqSubMode = payload.subMode;
+
+        if ( reqMode < NUM_OF_FP_MODES )
+        {
+            requestNewFPOperationMode( reqMode );
+
+            // check to avoid repeated initialization if the requested sub mode matches with current sub mode
+            if ( requestedSubMode != currentSubMode )
+            {
+                requestNewFPOperationSubMode(reqSubMode);
+            }
+            result = TRUE;  // TODO confirm if this is correct
+        }
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The testSetFPOpModePublishIntervalOverride function sets the override of the
  * operation mode publication interval.
  * @details \b Inputs: none