Index: firmware/App/Services/DDInterface.c
===================================================================
diff -u -r9c833ef5623ce842267e284d958820ac0dc3a7fc -rfff7eb3560421130e0cd4788f84bce0a8ee7ff44
--- firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision 9c833ef5623ce842267e284d958820ac0dc3a7fc)
+++ firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision fff7eb3560421130e0cd4788f84bce0a8ee7ff44)
@@ -382,6 +382,7 @@
  * @details \b Message \b Sent: Start/continue generate dialysate command.
  * @param qd Target dialysate flow rate (Qd).
  * @param quf Target ultrafiltration rate (Quf) (in mL/min).
+ * @param qsub Hemodiafiltration rate (QSub) (in mL/min).
  * @param dialTemp Target dialysate temperature in deg C.
  * @param bypass Flag indicating whether dialyzer should be bypassed.
  * @param acidConvFactor Conversion factor for the acid used.
@@ -390,7 +391,7 @@
  * @param bicarbonate Level of bicarbonate used in mEq/L.
  * @return none
  *************************************************************************/
-void cmdStartGenerateDialysate( F32 qd, F32 quf, F32 dialTemp, BOOL bypass, F32 acidConvFactor, F32 bicarbConvFactor, U32 sodium, U32 bicarbonate )
+void cmdStartGenerateDialysate( F32 qd, F32 quf, F32 qsub, F32 dialTemp, BOOL bypass, F32 acidConvFactor, F32 bicarbConvFactor, U32 sodium, U32 bicarbonate )
 {
     dialysateDeliveryCmdSet.start            = TRUE;
     dialysateDeliveryCmdSet.dialRate         = qd;
@@ -401,7 +402,7 @@
     dialysateDeliveryCmdSet.bicarbConvFactor = bicarbConvFactor;
     dialysateDeliveryCmdSet.sodium           = sodium;
     dialysateDeliveryCmdSet.bicarbonate      = bicarbonate;
-    dialysateDeliveryCmdSet.substitutionRate = 0.0F;
+    dialysateDeliveryCmdSet.substitutionRate = qsub;
 
 #ifndef TEST_UI_ONLY
     sendMessage( MSG_ID_DD_GEN_DIALYSATE_REQUEST_DATA, COMM_BUFFER_OUT_CAN_TD_2_DD, (U08*)(&dialysateDeliveryCmdSet), sizeof( DIALYSATE_DELIVERY_REQ_PAYLOAD_T ) );
@@ -461,6 +462,31 @@
 
 /*********************************************************************//**
  * @brief
+ * The cmdChangeQhdf function sends a generate dialysate command to the DD
+ * with a given new hemodiafiltration rate.
+ * @details \b Inputs: none
+ * @details \b Outputs: dialysateDeliveryCmdSet
+ * @details \b Message \b Sent: Continue generate dialysate command w/ new Quf.
+ * @param qhdf, hemodiafiltration flow rate (in mL/min).
+ * @return none
+ *************************************************************************/
+void cmdChangeQhdf( F32 qhdf )
+{
+    if ( TRUE == dialysateDeliveryCmdSet.start )
+    {
+        dialysateDeliveryCmdSet.substitutionRate = qhdf;
+#ifndef TEST_UI_ONLY
+        sendMessage( MSG_ID_DD_GEN_DIALYSATE_REQUEST_DATA, COMM_BUFFER_OUT_CAN_TD_2_DD, (U08*)(&dialysateDeliveryCmdSet), sizeof( DIALYSATE_DELIVERY_REQ_PAYLOAD_T ) );
+#endif
+    }
+    else
+    {
+        // TODO - s/w fault?
+    }
+}
+
+/*********************************************************************//**
+ * @brief
  * The cmdBypassDialyzer function sends a generate dialysate command to the DD
  * with a given flag indicating whether dialyzer should be bypassed.
  * @details \b Inputs: none
@@ -625,7 +651,19 @@
     }
 }
 
+/*********************************************************************//**
+ * @brief
+ * The getTDUFRate function gets the last set UF rate.
+ * @details \b Inputs: dialysateDeliveryCmdSet.ufRate
+ * @details \b Outputs: none
+ * @return Latest uf rate.
+ *************************************************************************/
+F32 getTDUFRate( void )
+{
+    return dialysateDeliveryCmdSet.ufRate;
+}
 
+
 /*************************************************************************
  *                       TEST SUPPORT FUNCTIONS
  *************************************************************************/