Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r4df8828df03ee996540084c57f9b46c0febc1e03 -rfacca88de0d4c72d943b59bad9264a9b0a031ae5
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 4df8828df03ee996540084c57f9b46c0febc1e03)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision facca88de0d4c72d943b59bad9264a9b0a031ae5)
@@ -20,6 +20,7 @@
 #include "Battery.h"
 #include "BloodFlow.h"
 #include "Buttons.h"
+#include "Compatible.h"
 #include "DGInterface.h"
 #include "DialInFlow.h"
 #include "DialOutFlow.h"
@@ -278,52 +279,63 @@
 BOOL signalUserInitiateTreatment( void )
 {
     BOOL result = FALSE;
+    DG_VERSIONS_T dgVersion = getDGVersion();
     REQUEST_REJECT_REASON_CODE_T rejReason = REQUEST_REJECT_REASON_NONE;
 
+    // Verify HD is in standby mode waiting for treatment start request
     if ( ( MODE_STAN != getCurrentOperationMode() ) || ( STANDBY_WAIT_FOR_TREATMENT_STATE != currentStandbyState ) )
     {
         rejReason = REQUEST_REJECT_REASON_NOT_ALLOWED_IN_CURRENT_MODE;
     }
-
-    if ( TRUE != isDGCommunicating() )
+    // Verify DG is communicating with HD
+    else if ( TRUE != isDGCommunicating() )
     {
         rejReason = REQUEST_REJECT_REASON_DG_COMM_LOST;
     }
-
-    if ( ( DG_MODE_STAN != getDGOpMode() ) || ( DG_STANDBY_MODE_STATE_IDLE != getDGSubMode() ) )
+    // Verify DG software is compatible with HD software
+    else if ( dgVersion.compatibilityRev != SW_COMPATIBILITY_REV )
     {
+        rejReason = REQUEST_REJECT_REASON_DG_INCOMPATIBLE;
+    }
+    // Verify DG is not busy
+    else if ( ( DG_MODE_STAN != getDGOpMode() ) || ( DG_STANDBY_MODE_STATE_IDLE != getDGSubMode() ) )
+    {
         rejReason = REQUEST_REJECT_REASON_DG_NOT_IN_STANDBY_IDLE_STATE;
     }
-
-    if ( FALSE == isBatteryCharged() )
+    // Verify HD battery has sufficient charge to hold up logic/sensors for at least 10 minutes
+    else if ( FALSE == isBatteryCharged() )
     {
         rejReason = REQUEST_REJECT_REASON_BATTERY_IS_NOT_CHARGED;
     }
-
-#ifndef _RELEASE_
-    if ( getSoftwareConfigStatus( SW_CONFIG_DISABLE_SERVICE_AND_DISINFECT_CHECK ) != SW_CONFIG_ENABLE_VALUE )
+#ifdef _RELEASE_
+    else
+#else
+    else if ( getSoftwareConfigStatus( SW_CONFIG_DISABLE_SERVICE_AND_DISINFECT_CHECK ) != SW_CONFIG_ENABLE_VALUE )
 #endif
     {
-        // This function checks both HD and DG service records and if any of them has failed, it fills the provided reject reason buffer
-        haveHDDGServicesBeenExpired( &rejReason );
-
-        if ( FALSE == isDGDisinfectValid() )
+        // Verify HD and DG are not over due for service
+        if ( haveHDDGServicesBeenExpired( &rejReason ) != TRUE )
         {
-            rejReason = REQUEST_REJECT_REASON_DG_DISINFECT_HAS_BEEN_EXPIRED;
+            // Verify DG is disinfected
+            if ( FALSE == isDGDisinfectValid() )
+            {
+                rejReason = REQUEST_REJECT_REASON_DG_DISINFECT_HAS_BEEN_EXPIRED;
+            }
+            else if ( getHeatDisinfectTemperatureSensorValue() > MAX_ALLOWED_RO_FILTER_TEMP_FOR_TX_C )
+            {
+                rejReason = REQUEST_REJECT_REASON_DG_RO_FILTER_TEMPERATURE_OUT_OF_RANGE;
+            }
         }
-
-        if ( getHeatDisinfectTemperatureSensorValue() > MAX_ALLOWED_RO_FILTER_TEMP_FOR_TX_C )
-        {
-            rejReason = REQUEST_REJECT_REASON_DG_RO_FILTER_TEMPERATURE_OUT_OF_RANGE;
-        }
     }
 
+    // If no reason to reject request to start treatment, set flag to initiate treatment workflow
     if ( REQUEST_REJECT_REASON_NONE == rejReason )
     {
         result                = TRUE;
         treatStartReqReceived = TRUE;
     }
 
+    // Respond to request to start treatment
     sendInitiateTreatmentResponseMsg( result, rejReason );
 
     return result;
@@ -674,24 +686,30 @@
         cmdStopDG();
     }
 
-    // If treatment start is requested by user, initiate treatment workflow (transition to treatment params mode).
-    if ( TRUE == treatStartReqReceived )
+    // If DG is communicating and we don't yet have DG version info, request it
+    if ( TRUE == isDGCommunicating() )
     {
-        BOOL startTreatment = TRUE;
+        DG_VERSIONS_T dgVersion = getDGVersion();
 
-        if ( TRUE == startTreatment )
+        if ( 0 == dgVersion.compatibilityRev )
         {
-            // Initialize treatment modes before starting a new treatment
-            initTreatParamsMode();
-            initPreTreatmentMode();
-            initTreatmentMode();
-            initPostTreatmentMode();
-            // Start treatment workflow with treatment parameters mode
-            requestNewOperationMode( MODE_TPAR );
-            treatStartReqReceived = FALSE;
+            sendFWVersionRequest();
         }
     }
 
+    // If treatment start is requested by user, initiate treatment workflow (transition to treatment params mode).
+    if ( TRUE == treatStartReqReceived )
+    {
+        // Initialize treatment modes before starting a new treatment
+        initTreatParamsMode();
+        initPreTreatmentMode();
+        initTreatmentMode();
+        initPostTreatmentMode();
+        // Start treatment workflow with treatment parameters mode
+        requestNewOperationMode( MODE_TPAR );
+        treatStartReqReceived = FALSE;
+    }
+
     return state;
 }
 
@@ -980,7 +998,7 @@
 
     getHDVersionDGServiceAndUsageData( &data );
 
-    if ( TRUE == data.isDGUsageInfoAviable )
+    if ( TRUE == data.isDGUsageInfoAvailable )
     {
         HD_USAGE_INFO_RECORD_T usageRecord;
         getNVRecord2Driver( GET_USAGE_RECORD, (U08*)&usageRecord, sizeof( HD_USAGE_INFO_RECORD_T ), 0, ALARM_ID_NO_ALARM );
@@ -1027,11 +1045,11 @@
  * @details Inputs: none
  * @details Outputs: none
  * @param rejReason pointer to the provided reject reason buffer to be send to UI
- * @return TRUE if the service time is still valid otherwise, FALSE
+ * @return TRUE if the service for HD or DG has expired otherwise FALSE
  ***********************************************************************/
 static BOOL haveHDDGServicesBeenExpired( REQUEST_REJECT_REASON_CODE_T* rejReason )
 {
-    BOOL status = TRUE;
+    BOOL status = FALSE;
     DG_SERVICE_AND_USAGE_DATA_T dgData;
     HD_SERVICE_RECORD_T hdServiceRecord;
 
@@ -1041,19 +1059,19 @@
     if ( TRUE == dgData.isDGServiceRecordAvailable )
     {
         U32 dgSrvcElapsedTimeS    = getRTCTimestamp() - dgData.dgServiceRecord.lastServiceEpochDate;
-        BOOL hasDGSrvcBeenExpired = ( dgSrvcElapsedTimeS > SERVICE_TIME_INTERVAL_S ? TRUE : FALSE );
         U32 hdSrvcElapsedTimeS    = getRTCTimestamp() - hdServiceRecord.lastServiceEpochDate;
+        BOOL hasDGSrvcBeenExpired = ( dgSrvcElapsedTimeS > SERVICE_TIME_INTERVAL_S ? TRUE : FALSE );
         BOOL hasHDSrvcBeenExpied  = ( hdSrvcElapsedTimeS > SERVICE_TIME_INTERVAL_S ? TRUE : FALSE );
 
         if ( TRUE == hasDGSrvcBeenExpired )
         {
-            status     = FALSE;
+            status     = TRUE;
             *rejReason = REQUEST_REJECT_REASON_DG_SERVICE_IS_DUE;
         }
 
         if ( TRUE == hasHDSrvcBeenExpied )
         {
-            status     = FALSE;
+            status     = TRUE;
             *rejReason = REQUEST_REJECT_REASON_HD_SERVICE_IS_DUE;
         }
     }