Index: firmware/App/Modes/ModeStandby.c
===================================================================
diff -u -r82bd1d24c050e79690a7f5b236e49dd7db7e2a91 -r5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51
--- firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 82bd1d24c050e79690a7f5b236e49dd7db7e2a91)
+++ firmware/App/Modes/ModeStandby.c	(.../ModeStandby.c)	(revision 5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51)
@@ -60,6 +60,7 @@
 static BOOL heatDisinfectStartReqReceived;                                                     ///< Flag indicates user has requested initiation of heat disinfect mode.
 static BOOL chemDisinfectStartReqReceived;                                                     ///< Flag indicates user has requested initiation of chemical disinfect mode.
 static BOOL chemDisinfectFlushStartReqReceived;                                                ///< Flag indicates user has requested initiation of chemical disinfect flush mode.
+static BOOL roPermeateSampleStartReqReceived;                                                  ///< Flag indicates user has requested initiation of RO permeate sample mode.
 static GENERIC_CONFIRM_ID_T disinfectCancelReqID;                                              ///< ID of requested cancel disinfect mode.
 static DG_DISINFECT_STATE_T dgDisinfectState;                                                  ///< DG disinfect state to be boadcast to UI.
 static U32 dataPublishCounter;                                                                 ///< Disinfects data publish counter.
@@ -501,7 +502,7 @@
  * The signalUserInitiateChemcialDisinfectFlushMode function handles user
  * initiation of chemical disinfect flush mode.
  * @details Inputs: currentStandbyState
- * @details Outputs: chemDisinfectFlushStartReqReceived
+ * @details Outputs: chemDisinfectFlushStartReqReceived, currentStandbyState
  * @return TRUE if signal accepted, FALSE if not
  *************************************************************************/
 BOOL signalUserInitiateChemcialDisinfectFlushMode( void )
@@ -534,6 +535,42 @@
 
 /*********************************************************************//**
  * @brief
+ * The signalUserInitiateROPermeateSampleMode function handles user
+ * initiation of RO permeate sample mode.
+ * @details Inputs: currentStandbyState
+ * @details Outputs: roPermeateSampleStartReqReceived, currentStandbyState
+ * @return TRUE if signal accepted, FALSE if not
+ *************************************************************************/
+BOOL signalUserInitiateROPermeateSampleMode( void )
+{
+    BOOL result                            = FALSE;
+    REQUEST_REJECT_REASON_CODE_T rejReason = REQUEST_REJECT_REASON_NOT_ALLOWED_IN_CURRENT_MODE;
+
+    if ( MODE_STAN == getCurrentOperationMode() )
+    {
+        if ( ( STANDBY_WAIT_FOR_DISINFECT_STATE == currentStandbyState ) || ( STANDBY_WAIT_FOR_TREATMENT_STATE == currentStandbyState ) )
+        {
+            if ( TRUE == isDGCommunicating() )
+            {
+                roPermeateSampleStartReqReceived = TRUE;
+                result                           = TRUE;
+                currentStandbyState              = STANDBY_WAIT_FOR_DISINFECT_STATE;
+                rejReason                        = REQUEST_REJECT_REASON_NONE;
+            }
+            else
+            {
+                rejReason = REQUEST_REJECT_REASON_DG_COMM_LOST;
+            }
+        }
+    }
+
+    sendDisinfectConfirmResponse( result, rejReason );
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
  * The signalInitiateStandbyDisinfectSubmode function handles user
  * initiation of setting the disinfects submode.
  * @details Inputs: currentStandbyState
Index: firmware/App/Modes/ModeStandby.h
===================================================================
diff -u -r19f13e67288117e7f81c1245a75cc6b5f8aaf899 -r5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51
--- firmware/App/Modes/ModeStandby.h	(.../ModeStandby.h)	(revision 19f13e67288117e7f81c1245a75cc6b5f8aaf899)
+++ firmware/App/Modes/ModeStandby.h	(.../ModeStandby.h)	(revision 5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51)
@@ -52,6 +52,7 @@
 BOOL signalUserInitiateHeatDisinfectMode( void );
 BOOL signalUserInitiateChemicalDisinfectMode( void );
 BOOL signalUserInitiateChemcialDisinfectFlushMode( void );
+BOOL signalUserInitiateROPermeateSampleMode( void );
 BOOL signalInitiateStandbyDisinfectSubmode( U32 cmd );
 
 BOOL testSetStandbyModePublishIntervalOverride( U32 ms );
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -re5167d0700038c1faf8b689b844a905f20c0d3c6 -r5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision e5167d0700038c1faf8b689b844a905f20c0d3c6)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 5c3d2c3b1f54008cfdf8fb66ed73f1a8015d9b51)
@@ -855,6 +855,10 @@
         {
             result = signalUserInitiateChemcialDisinfectFlushMode();
         }
+        else if ( DG_DISINFECT_RO_PERMEATE_SAMPLE_STATE == cmd ) // Command 4 = RO permeate sample
+        {
+            result = signalUserInitiateROPermeateSampleMode();
+        }
     }
 
     sendAckResponseMsg( (MSG_ID_T)message->hdr.msgID, COMM_BUFFER_OUT_CAN_HD_2_UI, result );