Index: firmware/App/Modes/TreatmentStop.c
===================================================================
diff -u -r1a36e9bd718b40ceaee21dd12eca2da353828e30 -r86dc010eacfdaad879327202bf03336e0c77ead3
--- firmware/App/Modes/TreatmentStop.c	(.../TreatmentStop.c)	(revision 1a36e9bd718b40ceaee21dd12eca2da353828e30)
+++ firmware/App/Modes/TreatmentStop.c	(.../TreatmentStop.c)	(revision 86dc010eacfdaad879327202bf03336e0c77ead3)
@@ -45,6 +45,8 @@
 static TREATMENT_STOP_STATE_T currentTxStopState;                                  ///< Current treatment stop state.
 static U32 bloodSittingTimerCtr;                                                   ///< Timer counter tracks time in this mode while blood is sitting.
 static U32 stopPublishTimerCtr;                                                    ///< Timer counter (in GP task intervals) counts time to next status broadcast.
+static BOOL airTrapFillInProgress;                                                 ///< Flag indicates an air trap fill is in progress.
+
 /// Interval (in task intervals) at which to publish treatment stop sub-mode data to CAN bus.
 static OVERRIDE_U32_T treatmentStopPublishInterval = { TREATMENT_STOP_DATA_PUBLISH_INTERVAL, TREATMENT_STOP_DATA_PUBLISH_INTERVAL, TREATMENT_STOP_DATA_PUBLISH_INTERVAL, 0 };
 
@@ -76,6 +78,7 @@
 {
     currentTxStopState = TREATMENT_STOP_RECIRC_STATE;   // Assume blood and dialysate will recirculate initially - will stop pump(s) as appropriate in state machine
     bloodSittingTimerCtr = 0;
+    airTrapFillInProgress = FALSE;
     stopPublishTimerCtr = TREATMENT_STOP_DATA_PUBLISH_INTERVAL;
 }
 
@@ -112,7 +115,6 @@
     setValvePosition( VDO, VALVE_POSITION_C_CLOSE );
 
     setupForBloodRecirculationState();
-
     setupForDialysateRecirculationState();
 
     signalInitiatePressureStabilization( USE_NORMAL_STABILIZATION_PERIOD );
@@ -182,9 +184,20 @@
     doorClosedRequired( TRUE, TRUE );
     // Open VBA and VBV valves to patient for blood recirculation
     setValvePosition( VBA, VALVE_POSITION_B_OPEN );
-    setValvePosition( VBV, VALVE_POSITION_B_OPEN );
-    // Start blood pump at prescribed flow rate
-    setBloodPumpTargetFlowRate( getTreatmentParameterU32( TREATMENT_PARAM_BLOOD_FLOW ), MOTOR_DIR_FORWARD, mode );
+    if ( TRUE == isAirTrapFillInProgress() )
+    {
+        // set BP to air trap fill rate if air trap fill has been initiated
+        setBloodPumpTargetFlowRate( AIR_TRAP_FILL_BLOOD_FLOW_RATE, MOTOR_DIR_FORWARD, mode );
+        // close VBV for fill
+        setValvePosition( VBV, VALVE_POSITION_C_CLOSE );
+    }
+    else
+    {
+        // Start blood pump at prescribed flow rate
+        setBloodPumpTargetFlowRate( getTreatmentParameterU32( TREATMENT_PARAM_BLOOD_FLOW ), MOTOR_DIR_FORWARD, mode );
+        // re-open VBV for blood recirculation
+        setValvePosition( VBV, VALVE_POSITION_B_OPEN );
+    }
     // Start Heparin pump as appropriate
     startHeparinPump();
     // Start air trap leveling control
@@ -290,6 +303,8 @@
             break;
     }
 
+    airTrapFillInProgress = isAirTrapFillInProgress();
+
     if ( priorSubState != currentTxStopState )
     {
         setCurrentSubState( (U32)currentTxStopState );
@@ -307,6 +322,8 @@
  * operations to set new states.
  * @details Inputs: state, flags
  * @details Outputs: flags handled
+ * @param state The Tx stop state that we're in now.  An invalid state will
+ * force a re-evaluation of actuator settings based on current status.
  * @return next treatment re-circulation state
  *************************************************************************/
 static TREATMENT_STOP_STATE_T handleTreatmentStopAlarmsAndSignals( TREATMENT_STOP_STATE_T state )
@@ -317,6 +334,21 @@
     BOOL bldAlarmsStatus          = ( ( TRUE == isAlarmActive( ALARM_ID_HD_BLOOD_LEAK_RECOVERING_PLEASE_WAIT ) ) &&
                                       ( FALSE == isAlarmActive( ALARM_ID_HD_BLOOD_LEAK_DETECTED ) ? TRUE : FALSE ) );
 
+    // if an air trap fill has started, set BP rate and VBV state accordingly
+    if ( ( airTrapFillInProgress != TRUE ) && ( TRUE == isAirTrapFillInProgress() ) )
+    {
+        // set BP to air trap fill rate if air trap fill has been initiated
+        setBloodPumpTargetFlowRate( AIR_TRAP_FILL_BLOOD_FLOW_RATE, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_CLOSED_LOOP );
+        // close VBV for fill
+        setValvePosition( VBV, VALVE_POSITION_C_CLOSE );
+    }
+    // if an air trap fill has completed, force re-evaluation of state to restore BP and VBV appropriately
+    else if ( ( TRUE == airTrapFillInProgress ) && ( isAirTrapFillInProgress() != TRUE ) )
+    {
+        state = NUM_OF_TREATMENT_STOP_STATES;  // make it look like we're changing states to force re-evaluation
+    }
+
+    // recovering from blood leak alarm?
     if ( TRUE == bldAlarmsStatus )
     {
         if ( ( TREATMENT_STOP_RECOVER_BLOOD_DETECT_STATE != state ) && ( dialysateRecircBlocked != TRUE ) )
@@ -325,6 +357,7 @@
             result = TREATMENT_STOP_RECOVER_BLOOD_DETECT_STATE;
         }
     }
+    // handling a saline bolus?
     else if ( ( TRUE == isSalineBolusStartRequested() ) || ( getSalineBolusState() != SALINE_BOLUS_STATE_IDLE ) )
     {
         // No need for setup function since the saline bolus exec function starts from Idle and sets the actuators
@@ -333,40 +366,39 @@
         if ( SALINE_BOLUS_STATE_IDLE == (U32)getSalineBolusState() )
         {
             // Send the first 4th level state here only when we are in idle
-            setCurrent4thLevelState( (U32)getSalineBolusState() );
+            setCurrent4thLevelState( (U32)SALINE_BOLUS_STATE_IDLE );
         }
     }
-    else
+    // Both unblocked and not in recirculate both state
+    else if ( ( TREATMENT_STOP_RECIRC_STATE != state ) && ( FALSE == dialysateRecircBlocked ) && ( FALSE == bloodRecircBlocked ) )
     {
-        // Both unblocked and not in recirculate both state
-        if ( ( TREATMENT_STOP_RECIRC_STATE != state ) && ( FALSE == dialysateRecircBlocked ) && ( FALSE == bloodRecircBlocked ) )
-        {
-            setupForBloodRecirculationState();
-            setupForDialysateRecirculationState();
-            result = TREATMENT_STOP_RECIRC_STATE;
-        }
-        // Both blocked and not in stopped state
-        else if ( ( TREATMENT_STOP_NO_RECIRC_STATE != state ) && ( TRUE == dialysateRecircBlocked ) && ( TRUE == bloodRecircBlocked ) )
-        {
-            setupForBloodRecirculationStopState();
-            setupForDialysateRecirculationStopState();
-            result = TREATMENT_STOP_NO_RECIRC_STATE;
-        }
-        // Dialysate recirculation blocked and not in blood recirc state
-        else if ( ( TREATMENT_STOP_RECIRC_BLOOD_ONLY_STATE != state ) && ( TRUE == dialysateRecircBlocked ) &&
-                  ( FALSE == bloodRecircBlocked ) )
-        {
-            setupForDialysateRecirculationStopState();
-            result = TREATMENT_STOP_RECIRC_BLOOD_ONLY_STATE;
-        }
-        // Blood recirculation blocked and not in dialysate recirc state
-        else if ( ( TREATMENT_STOP_RECIRC_DIALYSATE_ONLY_STATE != state ) && ( TRUE == bloodRecircBlocked ) &&
-                  ( FALSE == dialysateRecircBlocked ) )
-        {
-            setupForBloodRecirculationStopState();
-            result = TREATMENT_STOP_RECIRC_DIALYSATE_ONLY_STATE;
-        }
+        setupForBloodRecirculationState();
+        setupForDialysateRecirculationState();
+        result = TREATMENT_STOP_RECIRC_STATE;
     }
+    // Both blocked and not in stopped state
+    else if ( ( TREATMENT_STOP_NO_RECIRC_STATE != state ) && ( TRUE == dialysateRecircBlocked ) && ( TRUE == bloodRecircBlocked ) )
+    {
+        setupForBloodRecirculationStopState();
+        setupForDialysateRecirculationStopState();
+        result = TREATMENT_STOP_NO_RECIRC_STATE;
+    }
+    // Dialysate recirculation blocked and not in blood recirc state
+    else if ( ( TREATMENT_STOP_RECIRC_BLOOD_ONLY_STATE != state ) && ( TRUE == dialysateRecircBlocked ) &&
+              ( FALSE == bloodRecircBlocked ) )
+    {
+        setupForBloodRecirculationState();
+        setupForDialysateRecirculationStopState();
+        result = TREATMENT_STOP_RECIRC_BLOOD_ONLY_STATE;
+    }
+    // Blood recirculation blocked and not in dialysate recirc state
+    else if ( ( TREATMENT_STOP_RECIRC_DIALYSATE_ONLY_STATE != state ) && ( TRUE == bloodRecircBlocked ) &&
+              ( FALSE == dialysateRecircBlocked ) )
+    {
+        setupForBloodRecirculationStopState();
+        setupForDialysateRecirculationState();
+        result = TREATMENT_STOP_RECIRC_DIALYSATE_ONLY_STATE;
+    }
 
     return result;
 }