Index: firmware/App/Controllers/DryBiCart.c
===================================================================
diff -u -rf031f37d3f9985c1224472f2827cd180287c5621 -r22cf24fa6c521fd7c437aaf17c1b674d22537f4b
--- firmware/App/Controllers/DryBiCart.c	(.../DryBiCart.c)	(revision f031f37d3f9985c1224472f2827cd180287c5621)
+++ firmware/App/Controllers/DryBiCart.c	(.../DryBiCart.c)	(revision 22cf24fa6c521fd7c437aaf17c1b674d22537f4b)
@@ -69,12 +69,21 @@
 #define DRY_BICART_DRAIN_COND_ZERO_THRESH           0.05F                                       ///< Zero conductivity threshold
 #define DRY_BICART_DRAIN_COND_STABLE_SAMPLES        10U                                         ///< Debounce samples (10*50ms=500ms)
 
-/// Payload record structure for dry bicart fill request
+// Payload record structure for dry bicart fill request
 typedef struct
 {
     U32 startStop;                                                                              ///< Dry bicart fill request start:1 and stop: 0
 } DRY_BICART_FILL_START_CMD_PAYLOAD_T;
 
+// Enumeration of dry bicart state machine operation
+typedef enum DryBicart_StateMachines
+{
+    DRY_BICART_INITIAL_FILL = 0,                                                                ///< Dry bicart initial fill
+    DRY_BICART_SUPPLY,                                                                          ///< Dry bicart chamber fill
+    DRY_BICART_DRAIN,                                                                           ///< Dry bicart drain
+    NUM_OF_DRY_BICART_OPERATION                                                                 ///< Number of dry bicart operation
+} DRY_BICART_OPERATION_T;
+
 // ********** private data **********
 
 static DRY_BICART_FILL_EXEC_STATE_T dryBiCartFillExecState;                                     ///< Current state of dry bicart fill executive state machine.
@@ -105,8 +114,11 @@
 static U32 dryBiCartDrainCondStableCount;                                                       ///< Debounce counter for "zero" conductivity
 static U32 dryBiCartDrainTimePeriod;                                                            ///< Dry bicart drain time period
 
+static U08 pendingStartRequest;                                                                 ///< Dry bicart operation, fill or supply or drain request
+
 // ********** private function prototypes **********
 
+static void updateDrybicartOperation(void);
 // Fill
 static DRY_BICART_FILL_EXEC_STATE_T handleDryBicartFillWaterStartState( void );
 static DRY_BICART_FILL_EXEC_STATE_T handleDryBicartFillWaterEndState( void );
@@ -204,22 +216,44 @@
 /*********************************************************************//**
  * @brief
  * The execDryBicart function executes the set of dry bicarbonate cartridge
- * and Bicarb chamber fill related state machines.
- * @details \b Inputs: none
+ * , Bicarbonate chamber fill and bicarbonate cartridge drain related state machines one at time
+ * @details \b Inputs: pendingStartRequest
  * @details \b Outputs: none
  * @return none.
  *************************************************************************/
 void execDryBicart( void )
 {
-    // Dry bicart fill exec
-    execDryBicartFillMode();
+    updateDrybicartOperation();
 
-    // Fill Bicarb chamber F
-    execBicarbChamberFillMode();
+    //state = based on request ;
+    U08 state = pendingStartRequest;
+    U32 substate;
 
-    // Dry bicart drain exec
-    execDryBicartDrainMode();
+    switch ( state )
+    {
+        case DRY_BICART_INITIAL_FILL:
+            // Dry bicart fill exec
+            substate = execDryBicartFillMode();
+            break;
 
+        case DRY_BICART_SUPPLY:
+            // Fill Bicarb chamber F exec
+            // by default, supply state machine is selected ,ie. even if no request, supply state machine wait in BICARB_CHAMBER_START_STATE
+            substate = execBicarbChamberFillMode();
+            break;
+
+        case DRY_BICART_DRAIN:
+            // Dry bicart drain exec
+            substate = execDryBicartDrainMode();
+            break;
+
+        default:
+            // software fault
+            substate = 0xFFFFFFFF;
+            SET_ALARM_WITH_2_U32_DATA( ALARM_ID_DD_SOFTWARE_FAULT, SW_FAULT_ID_DRY_BICART_FILL_INVALID_EXEC_STATE, pendingStartRequest );
+            break;
+    }
+
     // Publish dry bicart data
     publishDryBicartData();
 }
@@ -397,15 +431,17 @@
  * @brief
  * The setBicarbChamberFillRequested function sets the chmaberFillRequest
  * flag value to be True.
- * @details \b Inputs: none
+ * @details \b Inputs: dryBiCartFillRequested, dryBiCartDrainRequested
  * @details \b Outputs: bicarbChamberFillRequested
  * @return TRUE if successful, FALSE if not.
  *************************************************************************/
 BOOL setBicarbChamberFillRequested( void )
 {
     BOOL result = FALSE;
+    BOOL internalFlag = dryBiCartFillRequested.data || dryBiCartDrainRequested.data;
+    BOOL overrideFlag = dryBiCartFillRequested.ovData || dryBiCartDrainRequested.ovData;
 
-    if ( FALSE == dryBiCartFillRequested.data && FALSE == dryBiCartDrainRequested.data )
+    if ( FALSE == internalFlag && FALSE == overrideFlag )
     {
         bicarbChamberFillRequested.data = TRUE;
         result = TRUE;
@@ -416,17 +452,39 @@
 
 /*********************************************************************//**
  * @brief
+ * The getBicarbChamberFillRequested function gets the chmaberFillRequest
+ * flag values
+ * @details \b Inputs: bicarbChamberFillRequested
+ * @details \b Outputs: none
+ * @return TRUE if successful, FALSE if not.
+ *************************************************************************/
+BOOL getBicarbChamberFillRequested( void )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == bicarbChamberFillRequested.data || TRUE == bicarbChamberFillRequested.ovData )
+    {
+        result = TRUE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The setBicartFillRequested function sets the bicart fill request
  * flag value to be True.
- * @details \b Inputs: none
+ * @details \b Inputs: bicarbChamberFillRequested, dryBiCartDrainRequested
  * @details \b Outputs: dryBiCartFillRequested
  * @return TRUE if successful, FALSE if not.
  *************************************************************************/
 BOOL setBicartFillRequested( void )
 {
     BOOL result = FALSE;
+    BOOL internalFlag = bicarbChamberFillRequested.data || dryBiCartDrainRequested.data;
+    BOOL overrideFlag = bicarbChamberFillRequested.ovData || dryBiCartDrainRequested.ovData;
 
-    if( FALSE == bicarbChamberFillRequested.data && FALSE == dryBiCartDrainRequested.data )
+    if( FALSE == internalFlag && FALSE == overrideFlag )
     {
         dryBiCartFillRequested.data = TRUE;
         result = TRUE;
@@ -437,17 +495,39 @@
 
 /*********************************************************************//**
  * @brief
+ * The getBicartFillRequested function gets the bicart fill request
+ * flag value
+ * @details \b Inputs: dryBiCartFillRequested
+ * @details \b Outputs: none
+ * @return TRUE if successful, FALSE if not.
+ *************************************************************************/
+BOOL getBicartFillRequested( void )
+{
+    BOOL result = FALSE;
+
+    if( TRUE == dryBiCartFillRequested.data || TRUE == dryBiCartFillRequested.ovData )
+    {
+         result = TRUE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The setBicartDrainRequested function sets the bicart drain request
  * flag value to be True.
- * @details \b Inputs: none
+ * @details \b Inputs: bicarbChamberFillRequested,dryBiCartFillRequested
  * @details \b Outputs: dryBiCartDrainRequested
  * @return TRUE if successful, FALSE if not.
  *************************************************************************/
 BOOL setBicartDrainRequested( void )
 {
     BOOL result = FALSE;
+    BOOL internalFlag = bicarbChamberFillRequested.data || dryBiCartFillRequested.data;
+    BOOL overrideFlag = bicarbChamberFillRequested.ovData || dryBiCartFillRequested.ovData;
 
-    if( FALSE == bicarbChamberFillRequested.data && FALSE == dryBiCartFillRequested.data )
+    if( FALSE == internalFlag && FALSE == overrideFlag )
     {
         dryBiCartDrainRequested.data = TRUE;
         result = TRUE;
@@ -458,6 +538,59 @@
 
 /*********************************************************************//**
  * @brief
+ * The getBicartDrainRequested function gets the bicart drain request
+ * flag value
+ * @details \b Inputs: dryBiCartDrainRequested
+ * @details \b Outputs: none
+ * @return TRUE if successful, FALSE if not.
+ *************************************************************************/
+BOOL getBicartDrainRequested( void )
+{
+    BOOL result = FALSE;
+
+    if( TRUE == dryBiCartDrainRequested.data || TRUE == dryBiCartDrainRequested.ovData )
+    {
+        result = TRUE;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The updateDrybicartOperation function initiates the water fill, bicarbonate supply or bicarbonate drain
+ * operation
+ * @details \b Inputs: pendingStartRequest
+ * @details \b Outputs: none
+ * @return none
+ *************************************************************************/
+static void updateDrybicartOperation(void)
+{
+    if( TRUE == getBicarbChamberFillRequested() )
+    {
+        // supply
+        pendingStartRequest = DRY_BICART_INITIAL_FILL;
+    }
+    else if ( TRUE == getBicartFillRequested() )
+    {
+        // fill
+        pendingStartRequest = DRY_BICART_SUPPLY;
+    }
+    else if ( TRUE == getBicartDrainRequested() )
+    {
+        //drain
+        pendingStartRequest = DRY_BICART_DRAIN;
+    }
+    else
+    {
+        // by default run supply state machine even if there is no request
+        // in this case state machine waits in BICARB_CHAMBER_START_STATE
+        pendingStartRequest = DRY_BICART_SUPPLY;
+    }
+}
+
+/*********************************************************************//**
+ * @brief
  * The handleDryBicartFillWaterStartState function initiates the water fill
  * into dry bicarbonate cartridge.
  * @details \b Inputs: none