Index: firmware/App/Modes/ModePreTreat.c
===================================================================
diff -u -r6f02ff4686ec9dfc60247e9ed3fc9c5cc7771543 -re7e2fef9fda6c6e876f7aba1c8f837d8aa713392
--- firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision 6f02ff4686ec9dfc60247e9ed3fc9c5cc7771543)
+++ firmware/App/Modes/ModePreTreat.c	(.../ModePreTreat.c)	(revision e7e2fef9fda6c6e876f7aba1c8f837d8aa713392)
@@ -16,6 +16,7 @@
 ***************************************************************************/
 
 #include "Buttons.h"
+#include "DDInterface.h"
 #include "ModePreTreat.h"
 #include "OperationModes.h"
 #include "Timers.h"
@@ -143,16 +144,38 @@
  *************************************************************************/
 static TD_PRE_TREATMENT_MODE_STATE_T handleRxState( void )
 {
-    BOOL paramsValid     = getValidTreatParamsReceived();
-    BOOL paramsConfirmed = getTreatParamsConfirmed();
-    TD_PRE_TREATMENT_MODE_STATE_T state = TD_PRE_TREATMENT_CONFIRM_RX_STATE;
+    BOOL paramsValid                       = getValidTreatParamsReceived();
+    BOOL paramsConfirmed                   = getTreatParamsConfirmed();
+    TD_PRE_TREATMENT_MODE_STATE_T state    = TD_PRE_TREATMENT_CONFIRM_RX_STATE;
+    DD_OP_MODE_T ddOpMode                  = getDDOpMode();
+    DD_PRE_GEN_DIALYSATE_STATE_T ddSubMode = (DD_PRE_GEN_DIALYSATE_STATE_T)getDDSubMode();
+    BOOL isDialysateGoodTodeliver          = TRUE; // TODO update with get API for getDialGoodToDeliverStatus
+    F32 bicarbConvFactor                   = BICARBONATE_CONVERSION_FACTOR;
+    F32 presUFVolumeL                      = 0.0F;
+    F32 presUFRateLHr                      = 0.0F;
 
     // Valid + confirmed – move to next state: Patient Connection
     if ( ( TRUE == paramsValid ) && ( TRUE == paramsConfirmed ) )
     {
+        // TODO this command of requesting dialysate delivery will move to appropriate state in pre-treatment once implemented
+        if ( ( ddOpMode == DD_MODE_PREG ) && ( ddSubMode == DD_PRE_GEN_DIALYSATE_WAIT_FOR_GEND ) )
+        {
+            presUFVolumeL = getTreatmentParameterF32( TREATMENT_PARAM_UF_VOLUME );
+            presUFRateLHr = presUFVolumeL / ( (F32)getTreatmentParameterU32( TREATMENT_PARAM_TREATMENT_DURATION ) / (F32)MIN_PER_HOUR );
+            // Direct DD to generate dialysate and bypass while priming blood
+            cmdStartGenerateDialysate( (F32)getTreatmentParameterU32( TREATMENT_PARAM_DIALYSATE_FLOW ), presUFRateLHr,
+                                       getTreatmentParameterF32( TREATMENT_PARAM_DIALYSATE_TEMPERATURE ), TRUE,
+                                       getTreatmentParameterF32( TREATMENT_PARAM_ACID_CONCENTRATE_CONV_FACTOR ),
+                                       bicarbConvFactor,
+                                       getTreatmentParameterU32( TREATMENT_PARAM_SODIUM ),
+                                       getTreatmentParameterU32( TREATMENT_PARAM_BICARBONATE ) );
+        }
         // TODO: when additional Pre-Treatment states are implemented, change to TD_PRE_TREATMENT_PATIENT_CONNECTION_STATE.
         // state = TD_PRE_TREATMENT_PATIENT_CONNECTION_STATE;
-        requestNewOperationMode( MODE_TREA );
+        if ( ( ddOpMode == DD_MODE_GEND ) && ( TRUE == isDialysateGoodTodeliver ) )
+        {
+            requestNewOperationMode( MODE_TREA );
+        }
     }
 
     return state;
Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -re9e339870c5ed01230963f00d400331ab879c91f -re7e2fef9fda6c6e876f7aba1c8f837d8aa713392
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision e9e339870c5ed01230963f00d400331ab879c91f)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision e7e2fef9fda6c6e876f7aba1c8f837d8aa713392)
@@ -208,6 +208,7 @@
 {
     TD_STANDBY_STATE_T state     = STANDBY_WAIT_FOR_TREATMENT_STATE;
     DD_OP_MODE_T ddOperationMode = getDDOpMode();
+    F32 bicarbConvFactor = BICARBONATE_CONVERSION_FACTOR;
 
 //    switch ( dgOperationMode )
 //    {
@@ -259,6 +260,13 @@
         respRecord.venPresLimitAsymmetricmmHg = getSysConfigTreatmentParameterU32DefaultValue( TREATMENT_PARAM_VEN_PRES_LIMIT_ASYMMETRIC );
         respRecord.tmpPresLimitWindowmmHg     = getSysConfigTreatmentParameterU32DefaultValue( TREATMENT_PARAM_TMP_PRES_LIMIT_WINDOW );
         sendPressureLimitsChangeResponse( &respRecord );
+        // start DD pre-gen  // TODO
+        cmdStartPreGenerateDialysate( (F32)getTreatmentParameterU32( TREATMENT_PARAM_DIALYSATE_FLOW ),
+                                      getTreatmentParameterF32( TREATMENT_PARAM_DIALYSATE_TEMPERATURE ),
+                                      getTreatmentParameterF32( TREATMENT_PARAM_ACID_CONCENTRATE_CONV_FACTOR ),
+                                      bicarbConvFactor,
+                                      getTreatmentParameterU32( TREATMENT_PARAM_SODIUM ),
+                                      getTreatmentParameterU32( TREATMENT_PARAM_BICARBONATE ) );
         // Start treatment workflow with pretreatment mode
         requestNewOperationMode( MODE_PRET );
         treatStartReqReceived = FALSE;
Index: firmware/App/Services/DDInterface.c
===================================================================
diff -u -re9e339870c5ed01230963f00d400331ab879c91f -re7e2fef9fda6c6e876f7aba1c8f837d8aa713392
--- firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision e9e339870c5ed01230963f00d400331ab879c91f)
+++ firmware/App/Services/DDInterface.c	(.../DDInterface.c)	(revision e7e2fef9fda6c6e876f7aba1c8f837d8aa713392)
@@ -46,6 +46,7 @@
 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.
 
 // DD command response
@@ -100,6 +101,14 @@
     ddStarted                                 = FALSE;
     ddStartCommandSent                        = FALSE;
 
+    preGenDialysateCmdSet.start               = FALSE;
+    preGenDialysateCmdSet.dialRate            = 0.0F;
+    preGenDialysateCmdSet.dialTemp            = 0.0F;
+    preGenDialysateCmdSet.acidConvFactor      = 0.0F;
+    preGenDialysateCmdSet.bicarbConvFactor    = 0.0F;
+    preGenDialysateCmdSet.sodium              = 0;
+    preGenDialysateCmdSet.bicarbonate         = 0;
+
     dialysateDeliveryCmdSet.start             = FALSE;
     dialysateDeliveryCmdSet.dialRate          = 0.0F;
     dialysateDeliveryCmdSet.ufRate            = 0.0F;
@@ -285,6 +294,38 @@
 
 /*********************************************************************//**
  * @brief
+ * The cmdStartPreGenerateDialysate function sends a pre generate dialysate command
+ * to the DD with a given set of details.  DD will transition to pre generate
+ * dialysate mode if it hasn't already.
+ * @details \b Inputs: none
+ * @details \b Outputs: preGenDialysateCmdSet
+ * @details \b Message \b Sent: Start/continue pre-generate dialysate command.
+ * @param qd Target dialysate flow rate (Qd).
+ * @param dialTemp Target dialysate temperature in deg C.
+ * @param acidConvFactor Conversion factor for the acid used.
+ * @param bicarbConvFactor Conversion factor for the bicarbonate used.
+ * @param sodium Level of sodium used in mEq/L.
+ * @param bicarbonate Level of bicarbonate used in mEq/L.
+ * @return none
+ *************************************************************************/
+void cmdStartPreGenerateDialysate( F32 qd, F32 dialTemp, F32 acidConvFactor, F32 bicarbConvFactor, U32 sodium, U32 bicarbonate )
+{
+    preGenDialysateCmdSet.start            = TRUE;
+    preGenDialysateCmdSet.dialRate         = qd;
+    preGenDialysateCmdSet.dialTemp         = dialTemp;
+    preGenDialysateCmdSet.acidConvFactor   = acidConvFactor;
+    preGenDialysateCmdSet.bicarbConvFactor = bicarbConvFactor;
+    preGenDialysateCmdSet.sodium           = sodium;
+    preGenDialysateCmdSet.bicarbonate      = bicarbonate;
+
+#ifndef TEST_UI_ONLY
+    sendMessage( MSG_ID_DD_PRE_GEN_DIALYSATE_REQUEST_DATA, COMM_BUFFER_OUT_CAN_TD_2_DD, (U08*)(&preGenDialysateCmdSet), sizeof( PRE_GEN_DIALYSATE_REQ_PAYLOAD_T ) );
+#endif
+//    ddStartCommandSent = TRUE;
+}
+
+/*********************************************************************//**
+ * @brief
  * The cmdStartGenerateDialysate function sends a generate dialysate command
  * to the DD with a given set of details.  DD will transition to dialysate
  * delivery mode if it hasn't already.
Index: firmware/App/Services/DDInterface.h
===================================================================
diff -u -re9e339870c5ed01230963f00d400331ab879c91f -re7e2fef9fda6c6e876f7aba1c8f837d8aa713392
--- firmware/App/Services/DDInterface.h	(.../DDInterface.h)	(revision e9e339870c5ed01230963f00d400331ab879c91f)
+++ firmware/App/Services/DDInterface.h	(.../DDInterface.h)	(revision e7e2fef9fda6c6e876f7aba1c8f837d8aa713392)
@@ -55,6 +55,7 @@
 BOOL setDDOpMode( MESSAGE_T *message );
 BOOL setDialysatePressure( MESSAGE_T *message );
 
+void cmdStartPreGenerateDialysate( F32 qd, F32 dialTemp, F32 acidConvFactor, F32 bicarbConvFactor, U32 sodium, U32 bicarbonate );
 void cmdStartGenerateDialysate( F32 qd, F32 quf, F32 dialTemp, BOOL bypass, F32 acidConvFactor, F32 bicarbConvFactor, U32 sodium, U32 bicarbonate );
 void cmdChangeQd( F32 qd );
 void cmdChangeQuf( F32 quf );