Index: firmware/App/Modes/ModeGenDialysate.c
===================================================================
diff -u -r0d7e60088d514e93c95313bea52b05afc81ba20f -r3f88f2878bfb58d9b67e05ed0717f6fbff136232
--- firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 0d7e60088d514e93c95313bea52b05afc81ba20f)
+++ firmware/App/Modes/ModeGenDialysate.c	(.../ModeGenDialysate.c)	(revision 3f88f2878bfb58d9b67e05ed0717f6fbff136232)
@@ -7,8 +7,8 @@
 *
 * @file    ModeGenDialysate.c
 *
-* @author  (last)      Vinayakam Mani
-* @date    (last)      28-May-2026
+* @author  (last)      Jashwant Gantyada
+* @date    (last)      30-Jun-2026
 *
 * @author  (original)  Vinayakam Mani
 * @date    (original)  06-Nov-2024
@@ -95,6 +95,7 @@
 static F32 dialysateToDialyzerFlowRate;                                                     ///< Current dialysate to dialyzer flow rate (ml/min)
 static U32 d48PumpSpeed;                                                                    ///< Initial D48 pump speed based on the Qd.
 static DD_GEND_ISO_UF_SUB_STATE_T isolatedUFSubState;                                       ///< Isolated UF run/pause sub-state.
+static BOOL isolatedUFVolumeSessionActive;                                                  ///< Flag indicating if an isolated UF volume session is in progress.
 
 // ********** private function prototypes **********
 
@@ -104,7 +105,7 @@
 static DD_GEND_MODE_STATE_T handleGenDDialysateDeliveryPauseState( void );
 static DD_GEND_MODE_STATE_T handleGenDSpentChamberFillState( void );
 static DD_GEND_MODE_STATE_T handleGenDBicarbChamberFillState( void );
-static DD_GEND_MODE_STATE_T handleGenDDialysateIsolatedUFState( void );
+static DD_GEND_MODE_STATE_T handleGenDIsolatedUFState( void );
 static F32 getGenDialysateTargetTemperature( void );
 static void updateDialysateToDialyzerFlowRate( void );
 static DD_GEND_MODE_STATE_T applyTDRequestedGenDialysateState( DD_GEND_MODE_STATE_T state );
@@ -152,6 +153,7 @@
     delayBypassStateFlag                        = TRUE;
     dialysateToDialyzerFlowRate                 = 0.0F;
     isolatedUFSubState                          = DD_GEND_ISO_UF_PAUSE_STATE;
+    isolatedUFVolumeSessionActive               = FALSE;
 
     //Initialize balancing chamber module
     initBalanceChamber();
@@ -261,7 +263,7 @@
             setValveState( D85_VALV, VALVE_STATE_CLOSED );
             setValveState( D31_VALV, VALVE_STATE_CLOSED );
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );    // Bicarb valve
                 setValveState( D64_VALV, VALVE_STATE_CLOSED );
@@ -346,7 +348,7 @@
             setValveState( D35_VALV, VALVE_STATE_OPEN );    // VDI
             setValveState( D40_VALV, VALVE_STATE_OPEN );    // VDO
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );    // Bicarb valve
                 setValveState( D64_VALV, VALVE_STATE_CLOSED );
@@ -369,7 +371,7 @@
             setValveState( D53_VALV, VALVE_STATE_OPEN );    // Drain valve
             setValveState( D34_VALV, VALVE_STATE_OPEN );    // Bypass valve
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );    // Bicarb valve
                 setValveState( D64_VALV, VALVE_STATE_CLOSED );
@@ -416,7 +418,7 @@
             setValveState( D53_VALV, VALVE_STATE_OPEN );    // Drain valve
             setValveState( D34_VALV, VALVE_STATE_OPEN );    // Bypass valve
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );    // Bicarb valve
                 setValveState( D64_VALV, VALVE_STATE_OPEN );    // Bicarb chamber purge valve
@@ -474,7 +476,7 @@
             setValveState( D34_VALV, VALVE_STATE_OPEN );
             setValveState( D53_VALV, VALVE_STATE_OPEN );
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );
                 setValveState( D64_VALV, VALVE_STATE_CLOSED );
@@ -483,8 +485,13 @@
 
         case DD_GEND_ISOLATED_UF_STATE:
             isolatedUFSubState = getIsolatedUFSubStateForUFRate();
-            resetUFVolumeDelivered();
 
+            if ( FALSE == isolatedUFVolumeSessionActive )
+            {
+                resetUFVolumeDelivered();
+                isolatedUFVolumeSessionActive = TRUE;
+            }
+
             transitionToBalChamberFill();
             // Activate Balancing Chamber Switching
             requestBalChamberSwitching( TRUE );
@@ -504,7 +511,7 @@
             setValveState( D81_VALV, VALVE_STATE_CLOSED );
             setValveState( D85_VALV, VALVE_STATE_CLOSED );
 
-            if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_DRY_BICARB ) == FALSE )
+            if ( getTestConfigStatus( TEST_CONFIG_DD_DISABLE_DRY_BICARB ) == FALSE )
             {
                 setValveState( D80_VALV, VALVE_STATE_OPEN );
                 setValveState( D64_VALV, VALVE_STATE_CLOSED );
@@ -612,7 +619,7 @@
                 break;
 
             case DD_GEND_ISOLATED_UF_STATE:
-                genDialysateState = handleGenDDialysateIsolatedUFState();
+                genDialysateState = handleGenDIsolatedUFState();
                 break;
 
             default:
@@ -783,7 +790,8 @@
  *************************************************************************/
 static DD_GEND_MODE_STATE_T applyTDRequestedGenDialysateState( DD_GEND_MODE_STATE_T state )
 {
-    DD_GEND_MODE_STATE_T requested = (DD_GEND_MODE_STATE_T)getTDRequestedGenDState();
+    DD_GEND_MODE_STATE_T requested  = (DD_GEND_MODE_STATE_T)getTDRequestedGenDState();
+    DD_GEND_MODE_STATE_T priorState = state;
 
     if ( state != requested )
     {
@@ -802,6 +810,12 @@
                     isDialDeliveryInProgress.data = TRUE;
                     state = DD_GEND_DIALYSATE_DELIVERY_STATE;
                 }
+                else if ( DD_GEND_ISOLATED_UF_STATE == state )
+                {
+                    setModeGenDStateTransition( DD_GEND_DIALYSATE_BYPASS_STATE );
+                    isDialDeliveryInProgress.data = FALSE;
+                    state = DD_GEND_DIALYSATE_BYPASS_STATE;
+                }
                 break;
 
             case DD_GEND_ISOLATED_UF_STATE:
@@ -815,6 +829,12 @@
         }
     }
 
+    if ( ( DD_GEND_ISOLATED_UF_STATE == priorState ) &&
+         ( DD_GEND_ISOLATED_UF_STATE != state ) )
+    {
+        isolatedUFVolumeSessionActive = FALSE;
+    }
+
     return state;
 }
 
@@ -840,19 +860,24 @@
 
 /*********************************************************************//**
  * @brief
- * The handleGenDDialysateIsolatedUFState function performs the
+ * The handleGenDIsolatedUFState function performs the
  * isolated ultrafiltration operations.
  * @details \b Inputs: none
  * @details \b Outputs: none
  * @return the current state of gen dialysate mode
  *************************************************************************/
-static DD_GEND_MODE_STATE_T handleGenDDialysateIsolatedUFState( void )
+static DD_GEND_MODE_STATE_T handleGenDIsolatedUFState( void )
 {
     DD_GEND_MODE_STATE_T state              = DD_GEND_ISOLATED_UF_STATE;
     BOOL balancingChambFillInProgress       = getBalancingChamberFillinProgressStatus();
 
-    if ( TRUE == getTestConfigStatus( TEST_CONFIG_DD_ENABLE_SPENT_CHAMBER_H_FILL ) )
+    // if TD asks for a different sub-state, transition out of isolated UF
+    if ( DD_GEND_ISOLATED_UF_STATE != getTDRequestedGenDState() )
     {
+        state = applyTDRequestedGenDialysateState( state );
+    }
+    else if ( getTestConfigStatus( TEST_CONFIG_DD_ENABLE_SPENT_CHAMBER_H_FILL ) == TRUE )
+    {
         if ( ( TRUE == pendingSpentChamberFill ) && ( FALSE == balancingChambFillInProgress ) )
         {
             setModeGenDStateTransition( DD_GEND_SPENT_CHAMBER_FILL_STATE );
@@ -862,7 +887,7 @@
         }
     }
 #ifdef __BICARB_CHAMBER_FILL__
-    if ( ( TRUE == pendingBicarbChamberFill ) && ( FALSE == balancingChambFillInProgress ) )
+    else if ( ( TRUE == pendingBicarbChamberFill ) && ( FALSE == balancingChambFillInProgress ) )
     {
         setModeGenDStateTransition( DD_GEND_BICARB_CHAMBER_FILL_STATE );
         pendingBicarbChamberFill = FALSE;
@@ -871,9 +896,6 @@
     }
 #endif
 
-    // If TD requests bypass, delivery, or another allowed sub-state, transition out of iso UF
-    state = applyTDRequestedGenDialysateState( state );
-
     if ( DD_GEND_ISOLATED_UF_STATE == state )
     {
         DD_GEND_ISO_UF_SUB_STATE_T desiredSubState = getIsolatedUFSubStateForUFRate();
@@ -883,8 +905,13 @@
             isolatedUFSubState = desiredSubState;
         }
 
-        execUFControl();
+        // Perform ultrafiltration
+        handleUFControl();
     }
+    else
+    {
+        stopUltrafiltration();
+    }
 
     return state;
 }
@@ -989,8 +1016,8 @@
 #endif
     else
     {
-        //Execute ultrafiltration
-        execUFControl();
+        // Perform ultrafiltration
+        handleUFControl();
     }
 
     return state;