Index: firmware/App/Modes/OperationModes.c
===================================================================
diff -u -rd7c545dff2f13dd75ebab0af997c45047c844f7a -r345a9b1694f4b0a9c9d3e9be45ee2e1f113dc942
--- firmware/App/Modes/OperationModes.c	(.../OperationModes.c)	(revision d7c545dff2f13dd75ebab0af997c45047c844f7a)
+++ firmware/App/Modes/OperationModes.c	(.../OperationModes.c)	(revision 345a9b1694f4b0a9c9d3e9be45ee2e1f113dc942)
@@ -50,6 +50,8 @@
 static OVERRIDE_U32_T ddOpModePublishInterval = { BROADCAST_DD_OP_MODE_INTERVAL, BROADCAST_DD_OP_MODE_INTERVAL, 0, 0 };
 static U32 dataPublishCounter;                                                      ///< Interval counter used to determine when to broadcast operation mode.  Initialize to 11 to stagger broadcast.
 static U32 currentSubState;                                                         ///< The currently active sub state.
+static U32 testRequestedSubMode;                                                    ///< Requested operation sub mode from dialin.
+static BOOL testChangeSubMode;                                                      ///< Flag to determine change operation sub mode request status.
 
 /// This matrix determines legal transitions from one mode to another.
 static const DD_OP_MODE_T MODE_TRANSITION_TABLE[ NUM_OF_DD_MODES - 1 ][ NUM_OF_DD_MODES - 1 ] =
@@ -74,6 +76,8 @@
 static U32  getDDOpModePublishInterval( void );
 static void broadcastOperationMode( void );
 static void sendOperationStatusEvent( void );
+static void testRequestNewDDOperationSubMode( void );
+static BOOL testValidateDDSubModeChangeRequest( DD_OP_MODE_T reqMode, U32 reqSubMode );
 
 /*********************************************************************//**
  * @brief
@@ -98,6 +102,8 @@
     currentSubMode     = 0;
     currentSubState    = NO_SUB_STATE;
     dataPublishCounter = DATA_PUBLISH_COUNTER_START_COUNT;
+    testRequestedSubMode   = 0;
+    testChangeSubMode      = FALSE;
 
     transitionToNewOperationMode( DD_MODE_INIT );
 
@@ -164,6 +170,13 @@
         sendOperationStatusEvent();
     }
 
+    // Is DD sub mode change request active?
+    if ( TRUE == testChangeSubMode )
+    {
+        testChangeSubMode = FALSE;
+        testRequestNewDDOperationSubMode();
+    }
+
     // mode specific processing to be done continuously
     switch ( currentMode )
     {
@@ -585,4 +598,151 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The testSetOperationSubMode function will transition to a given operation
+ * sub mode if the transition is legal.
+ * @details \b Inputs: none
+ * @details \b Outputs: request new sub mode function called
+ * @param message a pointer to the message to handle which includes the
+ * override value for the new mode and sub mode change.
+ * @return TRUE if request successful, FALSE if not
+ *************************************************************************/
+BOOL testSetOperationSubMode( MESSAGE_T *message )
+{
+    OP_MODES_DATA_T payload;
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        if( sizeof(OP_MODES_DATA_T) == message->hdr.payloadLen )
+        {
+            DD_OP_MODE_T reqMode;
+            U32 reqSubMode;
+
+            memcpy( (U08*)(&payload), message->payload, sizeof( OP_MODES_DATA_T ) );
+
+            reqMode = (DD_OP_MODE_T)payload.opMode;
+            reqSubMode = payload.subMode;
+
+            if ( reqMode < NUM_OF_DD_MODES )
+            {
+                // verify if the requested submode transition is valid
+                result = testValidateDDSubModeChangeRequest( reqMode, reqSubMode );
+
+                //send mode change request only if the requested sub mode transition is valid
+                if ( TRUE == result )
+                {
+                    if ( currentMode != reqMode )
+                    {
+                        requestNewOperationMode( reqMode );
+                        testRequestedSubMode = reqSubMode;
+                        testChangeSubMode = TRUE;
+                    }
+                    // requested sub mode change only as the requested operation mode is current mode
+                    else if ( currentSubMode != reqSubMode )
+                    {
+                        testRequestedSubMode = reqSubMode;
+                        testChangeSubMode = TRUE;
+                    }
+                }
+
+            }
+        }
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The testRequestNewDDOperationSubMode function requests transition to a new
+ * DD operation sub mode.
+ * @details \b Inputs: currentMode, testRequestedSubMode
+ * @details \b Outputs: none
+ * @return none
+ *************************************************************************/
+static void testRequestNewDDOperationSubMode( void )
+{
+    switch ( currentMode )
+    {
+        case DD_MODE_FAUL:
+            testSignalNewDDFaultSubMode( testRequestedSubMode );
+            break;
+
+        case DD_MODE_STAN:
+            testSignalNewDDStandbySubMode( testRequestedSubMode );
+            break;
+
+        case DD_MODE_PREG:
+            testSignalNewDDPreGenDialysateSubMode( testRequestedSubMode );
+            break;
+
+        case DD_MODE_GEND:
+            testSignalNewDDGenDialysateSubMode( testRequestedSubMode );
+            break;
+
+        case DD_MODE_POSG:
+            testSignalNewDDPostGenDialysateSubMode( testRequestedSubMode );
+            break;
+
+        case DD_MODE_SERV:
+        case DD_MODE_INIT:
+        case DD_MODE_HEAT:
+        case DD_MODE_HCOL:
+        case DD_MODE_ROPS:
+        default:
+            break;
+    }
+}
+
+/*********************************************************************//**
+ * @brief
+ * The testValidateDDSubModeChangeRequest function validates transition
+ * request to a new DD operation sub mode.
+ * @details \b Inputs: none
+ * @details \b Outputs: none
+ * @param reqMode DD operation mode enumeration
+ * @param reqSubMode operation sub mode requested
+ * @return TRUE if request is legal, FALSE if not.
+ *************************************************************************/
+static BOOL testValidateDDSubModeChangeRequest( DD_OP_MODE_T reqMode, U32 reqSubMode )
+{
+    BOOL result = FALSE;
+
+    switch ( reqMode )
+    {
+        case DD_MODE_FAUL:
+            result = testValidateDDFaultChangeReq( reqSubMode );
+            break;
+
+        case DD_MODE_STAN:
+            result = testValidateDDStandbyChangeReq( reqSubMode );
+            break;
+
+        case DD_MODE_PREG:
+            result = testValidateDDPreGenDialysateChangeReq( reqSubMode );
+            break;
+
+        case DD_MODE_GEND:
+            result = testValidateDDGenDialysateChangeReq( reqSubMode );
+            break;
+
+        case DD_MODE_POSG:
+            result = testValidateDDPostGenDialysateChangeReq( reqSubMode );
+            break;
+
+        // No need to validate the request for the following modes as it is not supported
+        case DD_MODE_SERV:
+        case DD_MODE_INIT:
+        case DD_MODE_HEAT:
+        case DD_MODE_HCOL:
+        case DD_MODE_ROPS:
+        default:
+            break;
+    }
+
+    return result;
+}
+
 /**@}*/