Index: firmware/App/Controllers/Valves.c
===================================================================
diff -u -r711ff90b0aab45c4acde333f4c9f11be9b62f383 -r729fd5d3a3a2d38f4fd4eff8068925941731bfc0
--- firmware/App/Controllers/Valves.c	(.../Valves.c)	(revision 711ff90b0aab45c4acde333f4c9f11be9b62f383)
+++ firmware/App/Controllers/Valves.c	(.../Valves.c)	(revision 729fd5d3a3a2d38f4fd4eff8068925941731bfc0)
@@ -52,6 +52,7 @@
 static U32 fpValveStatesPublicationTimerCounter;                                                                    ///< Timer counter used to schedule IOFP valve state publication to CAN bus.
 static U16 commandedValvesStates;                                                                                   ///< Initialize commanded valves states bit field.
 static U08 commandedBCValveStates;                                                                                  ///< Initialize balancing chamber commanded valves states bit field.
+static U08 commandedSpareValveStates;                                                                               ///< Initialize commanded spare valves states bit field.
 static U16 commandedIOFPValveStates;                                                                                ///< Initialize commanded IOFP valves states bit field.
 static U32 valveStateMismatchTimerCounter;                                                                          ///< Initialize valve state mismatch timer.
 static U32 pendingValveStateChanges[ DD_NUM_OF_VALVES ];                                                            ///< Delayed (pending) valve state changes.
@@ -109,6 +110,7 @@
     // Initialize the commanded valve states
     commandedValvesStates                   = ALL_VALVES_DEENERGIZED;
     commandedBCValveStates                  = ALL_VALVES_DEENERGIZED;
+    commandedSpareValveStates               = ALL_VALVES_DEENERGIZED;
     commandedIOFPValveStates                = ALL_VALVES_DEENERGIZED;
     valveStateMismatchTimerCounter          = 0;
     valvesStatesPublicationTimerCounter     = DATA_PUBLISH_COUNTER_START_COUNT;  // reset valves states publication timer
@@ -117,6 +119,7 @@
     // initially set all valves to de-energized state via FPGA
     setFPGADDValveStates( commandedValvesStates );
     setFPGABCValveStates( commandedBCValveStates );
+    setFPGASpareValveStates( commandedSpareValveStates );
     setFPGAIOFPValveStates( commandedIOFPValveStates );
 }
 
@@ -137,11 +140,13 @@
     U32 i;
     U16 readValvesStates    = getFPGADDValveStates();
     U08 readValveBCStates   = getFPGAValveBCStates();
+    U08 readValveSpStates   = getFPGAValveSpStates();
     U16 readValveIOFPStates = getFPGAIOFPValveStates();
 
     // Verify read back FPGA valve states match last commanded valve states
     if ( ( readValvesStates != commandedValvesStates ) ||
          ( readValveBCStates != commandedBCValveStates ) ||
+         ( readValveSpStates != commandedSpareValveStates ) ||
          ( readValveIOFPStates != commandedIOFPValveStates ) )
     {
         valveStateMismatchTimerCounter++; // increment valve state mismatch counter by 1
@@ -173,6 +178,7 @@
     readCommandedValveStates();
     setFPGADDValveStates( commandedValvesStates );
     setFPGABCValveStates( commandedBCValveStates );
+    setFPGASpareValveStates( commandedSpareValveStates );
     setFPGAIOFPValveStates( commandedIOFPValveStates );
 
     // Publish valve states on interval
@@ -193,9 +199,10 @@
     U32 i;
 
     // Initiliaze before updating commanded states
-    commandedValvesStates    = ALL_VALVES_DEENERGIZED;
-    commandedBCValveStates   = ALL_VALVES_DEENERGIZED;
-    commandedIOFPValveStates = ALL_VALVES_DEENERGIZED;
+    commandedValvesStates       = ALL_VALVES_DEENERGIZED;
+    commandedBCValveStates      = ALL_VALVES_DEENERGIZED;
+    commandedSpareValveStates   = ALL_VALVES_DEENERGIZED;
+    commandedIOFPValveStates    = ALL_VALVES_DEENERGIZED;
 
     // flag hydraulics valves that are currently commanded to be energized
     for ( i = FIRST_HYD_VALVE; i <= LAST_HYD_VALVE; i++ )
@@ -209,6 +216,12 @@
         commandedBCValveStates |= ( getValveState( i ) == ENERGIZED ? 0x01 << ( i - FIRST_BC_VALVE ) : 0 );
     }
 
+    // flag spare valves that are currently commanded to be energized
+    for ( i = FIRST_SP_VALVE; i <= LAST_SP_VALVE; i++ )
+    {
+        commandedSpareValveStates |= ( getValveState( i ) == ENERGIZED ? 0x01 << ( i - FIRST_SP_VALVE ) : 0 );
+    }
+
     // flag IOFP valves that are currently commanded to be energized
     for ( i = FIRST_IO_VALVE; i <= LAST_FP_VALVE; i++ )
     {
@@ -448,6 +461,7 @@
 
         data.valvesStatus       = commandedValvesStates;
         data.valvesBCStatus     = commandedBCValveStates;
+        data.valveSPStatus      = commandedSpareValveStates;
 
         for ( i = 0; i <= LAST_DD_VALVE; i++ )
         {
Index: firmware/App/Controllers/Valves.h
===================================================================
diff -u -r0b79c0e7dcf7f9e64c890447e83571d3123ab52c -r729fd5d3a3a2d38f4fd4eff8068925941731bfc0
--- firmware/App/Controllers/Valves.h	(.../Valves.h)	(revision 0b79c0e7dcf7f9e64c890447e83571d3123ab52c)
+++ firmware/App/Controllers/Valves.h	(.../Valves.h)	(revision 729fd5d3a3a2d38f4fd4eff8068925941731bfc0)
@@ -48,6 +48,7 @@
 {
     U16 valvesStatus;                             ///< 2 way valves status.
     U08 valvesBCStatus;                           ///< Balancing chamber valves status.
+    U08 valveSPStatus;                            ///< Spare valves status.
     U08 valvesSensedState[ LAST_DD_VALVE + 1 ];   ///< DD sensed valve states.
 } DD_VALVES_DATA_T;