Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -rbbd8081a9bd6fe63174f571bd60036145074e155 -r1a4fca64a161a9965f563f44f72e3251d1f7a929
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision bbd8081a9bd6fe63174f571bd60036145074e155)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 1a4fca64a161a9965f563f44f72e3251d1f7a929)
@@ -88,8 +88,15 @@
 
 // ********** private function prototypes **********
 
+static DIALYSIS_STATE_T handleDialysisUltrafiltrationState( void );
 static DIALYSIS_STATE_T handleDialysisSalineBolusState( void );
 
+static UF_STATE_T handleUFStartState( DIALYSIS_STATE_T *dialysisState );
+static UF_STATE_T handleUFPausedState( DIALYSIS_STATE_T *dialysisState );
+static UF_STATE_T handleUFRunningState( DIALYSIS_STATE_T *dialysisState );
+static UF_STATE_T handleUFOffState( DIALYSIS_STATE_T *dialysisState );
+static UF_STATE_T handleUFCompletedState( DIALYSIS_STATE_T *dialysisState );
+
 static SALINE_BOLUS_STATE_T handleSalineBolusIdleState( DIALYSIS_STATE_T *dialysisState );
 static SALINE_BOLUS_STATE_T handleSalineBolusWait4Pumps2Stop( DIALYSIS_STATE_T *dialysisState );
 static SALINE_BOLUS_STATE_T handleSalineBolusInProgressState( DIALYSIS_STATE_T *dialysisState );
@@ -517,6 +524,10 @@
             currentDialysisState = DIALYSIS_UF_STATE;
             break;
 
+        case DIALYSIS_UF_STATE:
+            currentDialysisState = handleDialysisUltrafiltrationState();
+            break;
+
         case DIALYSIS_SALINE_BOLUS_STATE:
             currentDialysisState = handleDialysisSalineBolusState();
             break;
@@ -532,6 +543,49 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleDialysisUltrafiltrationState function handles the ultrafiltration
+ * state of the Dialysis state machine.
+ * @details Inputs: currentUFState
+ * @details Outputs: currentUFState
+ * @return next Dialysis state.
+ *************************************************************************/
+static DIALYSIS_STATE_T handleDialysisUltrafiltrationState( void )
+{
+    DIALYSIS_STATE_T result = DIALYSIS_UF_STATE;
+
+    switch ( currentUFState )
+    {
+        case UF_START_STATE:
+            currentUFState = handleUFStartState( &result );
+            break;
+
+        case UF_PAUSED_STATE:
+            currentUFState = handleUFPausedState( &result );
+            break;
+
+        case UF_RUNNING_STATE:
+            currentUFState = handleUFRunningState( &result );
+            break;
+
+        case UF_OFF_STATE:
+            currentUFState = handleUFOffState( &result );
+            break;
+
+        case UF_COMPLETED_STATE:
+            currentUFState = handleUFCompletedState( &result );
+            break;
+
+        default:
+            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_HD_SOFTWARE_FAULT, SW_FAULT_ID_DIALYSIS_INVALID_UF_STATE, currentUFState )
+            currentUFState = UF_COMPLETED_STATE;
+            break;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleDialysisSolutionInfusionState function handles the solution
  * infustion state of the Dialysis state machine.
  * @details Inputs: currentSalineBolusState
@@ -571,6 +625,199 @@
 
 /*********************************************************************//**
  * @brief
+ * The handleUFStartState function handles the Start state of the
+ * ultrafiltration state machine.
+ * @details Inputs: maxUFVolumeML
+ * @details Outputs: if ultrafiltration prescribed, ultrafiltration time is
+ * initialized.
+ * @param dialysisState next dialysis state
+ * @return next ultrafiltration state.
+ *************************************************************************/
+static UF_STATE_T handleUFStartState( DIALYSIS_STATE_T *dialysisState )
+{
+    UF_STATE_T result;
+
+    if ( maxUFVolumeML < NEARLY_ZERO )
+    {
+        result = UF_OFF_STATE;
+    }
+    else
+    {
+        lastUFTimeStamp = getMSTimerCount();
+        uFTimeMS = 0;
+        result = UF_RUNNING_STATE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleUFPausedState function handles the Paused state of the
+ * ultrafiltration state machine.
+ * @details Inputs: none
+ * @details Outputs: if ultrafiltration resumption requested, UF time is set to resume.
+ * @param dialysisState next dialysis state
+ * @return next ultrafiltration state.
+ *************************************************************************/
+static UF_STATE_T handleUFPausedState( DIALYSIS_STATE_T *dialysisState )
+{
+    UF_STATE_T result = UF_PAUSED_STATE;
+
+    // Calculate UF volumes and provide to dialysate outlet pump controller
+    updateUFVolumes();
+
+    // Handle saline bolus start request from user
+    if ( TRUE == salineBolusStartRequested )
+    {
+        salineBolusAutoResumeUF = FALSE;
+        // Go to saline bolus state if we can
+        if ( SALINE_BOLUS_STATE_IDLE == currentSalineBolusState )
+        {
+            *dialysisState = DIALYSIS_SALINE_BOLUS_STATE;
+        }
+        else
+        {
+            salineBolusStartRequested = FALSE;
+        }
+    }
+    // Handle auto-resume after saline bolus
+    else if ( TRUE == salineBolusAutoResumeUF )
+    {
+        salineBolusAutoResumeUF = FALSE;
+        // Set outlet pump to dialysate rate + set UF rate
+        setDialOutPumpTargetRate( setDialysateFlowRate + FLOAT_TO_INT_WITH_ROUND( setUFRate ), MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_CLOSED_LOOP );
+        // Restart UF time accumulation for reference volume calculation
+        lastUFTimeStamp = getMSTimerCount();
+        // Resume UF
+        result = UF_RUNNING_STATE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleUFRunningState function handles the Running state of the
+ * ultrafiltration state machine.
+ * @details Inputs: ms timer, lastUFTimeStamp
+ * @details Outputs: UF timer incremented, UF volumes updated and provided to DPo
+ * pump controller.
+ * @param dialysisState next dialysis state
+ * @return next ultrafiltration state.
+ *************************************************************************/
+static UF_STATE_T handleUFRunningState( DIALYSIS_STATE_T *dialysisState )
+{
+    UF_STATE_T result = UF_RUNNING_STATE;
+    U32 newTime = getMSTimerCount();
+    U32 msSinceLast = calcTimeBetween( lastUFTimeStamp, newTime );
+
+    // Update UF time
+    uFTimeMS += msSinceLast;
+    lastUFTimeStamp = newTime;
+
+    // Update UF ref volume in UF running state only
+    refUFVolume += ( ( (F32)msSinceLast / MS_PER_SECOND ) / SEC_PER_MIN ) * setUFRate;
+
+    // Calculate UF volumes and provide to dialysate outlet pump controller
+    updateUFVolumes();
+
+    // If we have reached target UF volume, UF is complete
+    if ( refUFVolume >= maxUFVolumeML )
+    {
+        result = UF_COMPLETED_STATE;
+    }
+    // Handle saline bolus start request from user
+    else if ( TRUE == salineBolusStartRequested )
+    {
+        if ( SALINE_BOLUS_STATE_IDLE == currentSalineBolusState )
+        {
+            // Since we were doing UF prior to saline bolus, we want to auto-resume when done
+            salineBolusAutoResumeUF = TRUE;
+            // Go to UF paused state
+            result = UF_PAUSED_STATE;
+            // Go to saline bolus state
+            *dialysisState = DIALYSIS_SALINE_BOLUS_STATE;
+        }
+        else
+        {
+            salineBolusStartRequested = FALSE;
+        }
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleUFCompletedOrOffState function handles the UF Off state
+ * of the ultrafiltration state machine.
+ * @details Inputs: none
+ * @details Outputs: UF volumes updated and provided to DPo pump controller.
+ * @param dialysisState next dialysis state
+ * @return next ultrafiltration state
+ *************************************************************************/
+static UF_STATE_T handleUFOffState( DIALYSIS_STATE_T *dialysisState )
+{
+    UF_STATE_T result = UF_OFF_STATE;
+
+    // Calculate UF volumes and provide to dialysate outlet pump controller
+    updateUFVolumes();
+
+    // Handle saline bolus start request from user
+    if ( TRUE == salineBolusStartRequested )
+    {
+        salineBolusAutoResumeUF = FALSE;
+        // Go to saline bolus state
+        if ( SALINE_BOLUS_STATE_IDLE == currentSalineBolusState )
+        {
+            *dialysisState = DIALYSIS_SALINE_BOLUS_STATE;
+        }
+        else
+        {
+            salineBolusStartRequested = FALSE;
+        }
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The handleUFCompletedState function handles the UF Completed
+ * state of the ultrafiltration state machine.  This is a terminal state.
+ * @details Inputs: none
+ * @details Outputs: UF volumes updated and provided to DPo pump controller.
+ * @param dialysisState next dialysis state
+ * @return next ultrafiltration state
+ *************************************************************************/
+static UF_STATE_T handleUFCompletedState( DIALYSIS_STATE_T *dialysisState )
+{
+    UF_STATE_T result = UF_COMPLETED_STATE;
+
+    // Calculate UF volumes and provide to dialysate outlet pump controller
+    updateUFVolumes();
+
+    // Handle saline bolus start request from user
+    if ( TRUE == salineBolusStartRequested )
+    {
+        salineBolusAutoResumeUF = FALSE;
+        // Go to saline bolus state
+        if ( SALINE_BOLUS_STATE_IDLE == currentSalineBolusState )
+        {
+            *dialysisState = DIALYSIS_SALINE_BOLUS_STATE;
+        }
+        else
+        {
+            salineBolusStartRequested = FALSE;
+        }
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleSalineBolusIdleState function handles the idle state of the
  * saline bolus state machine.
  * @details Inputs: none