Index: firmware/App/Services/DDInterface.c
===================================================================
diff -u -r927dfd6e109af46160e5aef687f1b7c286d24703 -r08fdaaf70ab5133cbe7d019905f745074a756027
--- firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision 927dfd6e109af46160e5aef687f1b7c286d24703)
+++ firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision 08fdaaf70ab5133cbe7d019905f745074a756027)
@@ -43,13 +43,17 @@
 static BOOL ddStartCommandSent;                                             ///< Flag indicates command to start DD has been sent.
 static BOOL ddStarted;                                                      ///< Flag indicates whether we have commanded the DD to start or stop.
 static BOOL isDialysateGoodtoDeliver;                                       ///< Flag indicating whether dialysate is good to deliver.
+static U32 currentGenDState;                                                ///< Current state of DD GenD mode.
+static U32 isBalChamberSwitchingActive;                                     ///< Flag indicating whether bc is switching.
 
 static BOOL ddOpModeDataFreshFlag;                                          ///< Flag to signal the handleDDOpMode() to process fresh dd op mode data.
 static BOOL ddDialysatePressureFreshFlag;                                   ///< Flag to signal
 
 static PRE_GEN_DIALYSATE_REQ_PAYLOAD_T preGenDialysateCmdSet;               ///< Set of pre-generate dialysate parameters to send to the DD
 static DIALYSATE_DELIVERY_REQ_PAYLOAD_T dialysateDeliveryCmdSet;            ///< Set of dialysate delivery parameters to send to the DD during treatment.
 
+static PRIME_DATA_REQ_PAYLOAD_T primeDataCmdSet;
+
 // DD command response
 static DD_CMD_RESPONSE_T ddCmdResp[ NUM_OF_DD_COMMANDS ];                   ///< Keep the latest DD command response for each command.
 
@@ -73,6 +77,7 @@
     ddSubMode                               = 0;
     dialysatePressure                       = 0.0F;
     isDialysateGoodtoDeliver                = FALSE;
+    currentGenDState                        = 0;
 
     ddOpModeDataFreshFlag                   = FALSE;
     ddDialysatePressureFreshFlag            = FALSE;
@@ -120,6 +125,10 @@
     dialysateDeliveryCmdSet.bicarbConvFactor  = 0.0F;
     dialysateDeliveryCmdSet.sodium            = 0;
     dialysateDeliveryCmdSet.bicarbonate       = 0;
+    dialysateDeliveryCmdSet.substitutionRate  = 0.0F;
+
+    primeDataCmdSet.chamberHValveOpen         = FALSE;
+    primeDataCmdSet.primeFluidDiscardStart    = FALSE;
     //dialysateDeliveryCmdSet.substitutionRate  = 0.0F;
 }
 
@@ -267,6 +276,7 @@
     if ( message->hdr.payloadLen == sizeof( GEN_DIALYSATE_MODE_DATA_T )  )
     {
         isDialysateGoodtoDeliver = payload.isDialysateGoodtoDeliver;
+        currentGenDState = payload.genDialysateExecState;
         result = TRUE;
     }
     else
@@ -280,6 +290,38 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleBalancingChamberData function sets the latest DD balancing
+ * chamber switching status reported by the DD.
+ * @details \b Alarm: ALARM_ID_TD_SOFTWARE_FAULT if message is invalid.
+ * @details \b Inputs: none
+ * @details \b Outputs: isBalChamberSwitchingActive
+ * @param message Pointer to the DD balancing chamber data broadcast message
+ * @return TRUE if message handled successfully, FALSE if not
+ *************************************************************************/
+BOOL handleBalancingChamberData( MESSAGE_T *message )
+{
+    BOOL result = FALSE;
+    BAL_CHAMBER_DATA_T payload;
+
+    if ( message->hdr.payloadLen == sizeof( BAL_CHAMBER_DATA_T )  )
+    {
+        // parse message payload
+        memcpy( &payload, &message->payload[ 0 ], sizeof( BAL_CHAMBER_DATA_T ) );
+
+        isBalChamberSwitchingActive = payload.isBalChamberSwitchingActive;
+        result = TRUE;
+    }
+    else
+    {
+#ifndef TEST_UI_ONLY
+        SET_ALARM_WITH_2_U32_DATA( ALARM_ID_TD_SOFTWARE_FAULT, SW_FAULT_ID_INVALID_DD_BAL_CHAMBER_DATA, (U32)message->hdr.payloadLen );
+#endif
+    }
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getDialysatePressure function gets the latest reported dialysate
  * pressure.
  * @details \b Inputs: dialysatePressure
@@ -307,6 +349,31 @@
 
 /*********************************************************************//**
  * @brief
+ * The getCurrentGenDState function gets the current state of gen dialysate.
+ * @details \b Inputs: currentGenDState
+ * @details \b Outputs: none
+ * @return Current state of gen dialysate
+ *************************************************************************/
+BOOL getCurrentGenDState( void )
+{
+    return currentGenDState;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The getBalChamberSwitchingStatus function returns whether the DD
+ * balancing chamber is currently switching.
+ * @details \b Inputs: isBalChamberSwitchingActive
+ * @details \b Outputs: none
+ * @return TRUE if balancing chamber switching is active, FALSE if not
+ *************************************************************************/
+BOOL getBalChamberSwitchingStatus( void )
+{
+    return isBalChamberSwitchingActive;
+}
+
+/*********************************************************************//**
+ * @brief
  * The setDialysatePressure function sets the latest dialysate pressure
  * reported by the DD sub-system.
  * @details \b Alarm: ALARM_ID_TD_SOFTWARE_FAULT if message invalid.
@@ -625,7 +692,58 @@
     }
 }
 
+/*********************************************************************//**
+ * @brief
+ * The cmdDDChamberHValveOpen function sends a prime data request to the DD
+ * to open or close the Chamber H vent valve (D47) during dialysate circuit
+ * prime depressurization.
+ * @details \b Message \b Sent: MSG_ID_DD_TD_PRIME_REQUEST_DATA
+ * @details \b Inputs: none
+ * @details \b Outputs: primeDataCmdSet
+ * @param valveOpenRequest TRUE to open the Chamber H vent valve, FALSE to close it
+ * @return none
+ *************************************************************************/
+void cmdDDChamberHValveOpen( BOOL valveOpenRequest )
+{
+    if ( TRUE == dialysateDeliveryCmdSet.start )
+    {
+        primeDataCmdSet.chamberHValveOpen = valveOpenRequest;
+#ifndef TEST_UI_ONLY
+        sendMessage( MSG_ID_DD_TD_PRIME_REQUEST_DATA, COMM_BUFFER_OUT_CAN_TD_2_DD, (U08*)(&primeDataCmdSet), sizeof( PRIME_DATA_REQ_PAYLOAD_T ) );
+#endif
+    }
+    else
+    {
+        // TODO - s/w fault?
+    }
+}
 
+/*********************************************************************//**
+ * @brief
+ * The cmdDDprimeFluidDiscard function sends a prime data request to the DD
+ * to start or stop discarding the priming fluid via the ultrafiltration
+ * pump (D76) during priming fluid discard and dialyzer reverse prime.
+ * @details \b Message \b Sent: MSG_ID_DD_TD_PRIME_REQUEST_DATA
+ * @details \b Inputs: none
+ * @details \b Outputs: primeDataCmdSet
+ * @param primeFluidDiscardRequest TRUE to start priming fluid discard, FALSE to stop it
+ * @return none
+ *************************************************************************/
+void cmdDDprimeFluidDiscard( BOOL primeFluidDiscardRequest )
+{
+    if ( TRUE == dialysateDeliveryCmdSet.start )
+    {
+        primeDataCmdSet.primeFluidDiscardStart = primeFluidDiscardRequest;
+#ifndef TEST_UI_ONLY
+        sendMessage( MSG_ID_DD_TD_PRIME_REQUEST_DATA, COMM_BUFFER_OUT_CAN_TD_2_DD, (U08*)(&primeDataCmdSet), sizeof( PRIME_DATA_REQ_PAYLOAD_T ) );
+#endif
+    }
+    else
+    {
+        // TODO - s/w fault?
+    }
+}
+
 /*************************************************************************
  *                       TEST SUPPORT FUNCTIONS
  *************************************************************************/