Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r93a439cf9d1b347e23b84d1156417380ee01efaa -r0b87f7e6142dc3710db5c32a0c7c6694343dd717
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 93a439cf9d1b347e23b84d1156417380ee01efaa)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 0b87f7e6142dc3710db5c32a0c7c6694343dd717)
@@ -16,9 +16,10 @@
 
 #include "AlarmLamp.h"
 #include "BloodFlow.h"
+#include "Buttons.h"
+#include "DGInterface.h"
 #include "DialInFlow.h"
 #include "DialOutFlow.h"
-#include "Buttons.h"
 #include "OperationModes.h"
 #include "SystemCommMessages.h"
 #include "ModeStandby.h"
@@ -27,8 +28,24 @@
     static U32 start;
 #endif
 
+// ********** private definitions **********
+
+/// Sub-mode states while in standby mode
+typedef enum Standby_States
+{
+    STANDBY_START_STATE = 0,                ///< Start standby
+    STANDBY_FLUSH_DG_LINES_STATE,           ///<
+    STANDBY_DRAIN_RESERVOIR_STATE,          ///<
+    STANDBY_WAIT_FOR_PRIME_STATE,           ///<
+    STANDBY_FILL_RESERVOIR_STATE,           ///<
+    STANDBY_WAIT_FOR_TREATMENT_STATE,       ///<
+    NUM_OF_STANDBY_STATES                   ///< Number of standby states (sub-modes).
+} STANDBY_STATE_T;
+
 // ********** private data **********
 
+static STANDBY_STATE_T currentStandbyState;                     ///< Current state (sub-mode) of standby mode.
+
 // ********** private function prototypes **********
 
 /*************************************************************************
@@ -42,6 +59,7 @@
  *************************************************************************/
 void initStandbyMode( void )
 {
+    currentStandbyState = STANDBY_START_STATE;
 }
 
 /*************************************************************************
@@ -55,10 +73,9 @@
  *************************************************************************/
 void transitionToStandbyMode( void )
 {
-    // temporary test code - TODO - remove later
-    homeBloodPump();
-    homeDialInPump();
-    homeDialOutPump();
+    // re-initialize when transitioning to standby mode
+    initStandbyMode();
+
 #ifndef UF_TEST_ENABLED
     setBloodPumpTargetFlowRate( 0, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_CLOSED_LOOP );
     setDialInPumpTargetFlowRate( 0, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_CLOSED_LOOP );
@@ -81,12 +98,94 @@
 void execStandbyMode( void )
 {
     BOOL stop = isStopButtonPressed();
+    DG_OP_MODE_T dgOpMode = getDGOpMode();  // TODO - the DG mode & sub-mode come as a pair at interval - they MUST be kept together.
+    U32 dgSubMode = getDGSubMode();
 
-    if ( TRUE == stop )
+    // treatment mode state machine
+    switch ( currentStandbyState )
     {
-        cmdStartDG();
-        requestNewOperationMode( MODE_PRES );
+        case STANDBY_START_STATE:
+            // temporary test code - TODO - remove later
+            homeBloodPump();
+            homeDialInPump();
+            homeDialOutPump();
+            cmdSetDGDialysateTargetTemps( 39.0, 37.0 );
+            cmdSetDGActiveReservoir( DG_RESERVOIR_2 );
+            cmdStartDG();
+            currentStandbyState = STANDBY_FLUSH_DG_LINES_STATE;
+            break;
+
+        case STANDBY_FLUSH_DG_LINES_STATE:
+            // temporary test code - TODO - remove later
+            if ( DG_MODE_CIRC == dgOpMode )
+            {
+                if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
+                {
+                    cmdStartDGDrain( 100 );
+                }
+            }
+            else if ( DG_MODE_DRAI == dgOpMode )
+            {
+                currentStandbyState = STANDBY_DRAIN_RESERVOIR_STATE;
+            }
+            else
+            {
+                cmdStartDG();
+            }
+            break;
+
+        case STANDBY_DRAIN_RESERVOIR_STATE:
+            // temporary test code - TODO - remove later
+            if ( DG_MODE_CIRC == dgOpMode )
+            {
+                currentStandbyState = STANDBY_WAIT_FOR_PRIME_STATE;
+            }
+            break;
+
+        case STANDBY_WAIT_FOR_PRIME_STATE:
+            // temporary test code - TODO - remove later
+            if ( DG_MODE_CIRC == dgOpMode )
+            {
+                if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
+                {
+                    cmdStartDGFill( 1500 );
+                }
+            }
+            else if ( DG_MODE_FILL == dgOpMode )
+            {
+                currentStandbyState = STANDBY_FILL_RESERVOIR_STATE;
+            }
+            break;
+
+        case STANDBY_FILL_RESERVOIR_STATE:
+            // temporary test code - TODO - remove later
+            if ( DG_MODE_CIRC == dgOpMode )
+            {
+                cmdSetDGActiveReservoir( DG_RESERVOIR_1 );
+                currentStandbyState = STANDBY_WAIT_FOR_TREATMENT_STATE;
+            }
+            break;
+
+        case STANDBY_WAIT_FOR_TREATMENT_STATE:
+            // TODO - test code
+            if ( TRUE == stop )
+            {
+                if ( DG_MODE_CIRC == getDGOpMode() )
+                {
+                    if ( DG_RECIRCULATE_MODE_STATE_RECIRC_WATER == dgSubMode )
+                    {
+                        requestNewOperationMode( MODE_PRES );
+                    }
+                }
+            }
+            break;
+
+        default:
+            // TODO - s/w fault
+            currentStandbyState = STANDBY_START_STATE;
+            break;
     }
+
 #ifdef RM46_EVAL_BOARD_TARGET
     if ( TRUE == didTimeout( start, 5000U ) )
     {