Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -rc230be1bd4296324bf5dfc288c212eb7c2ce5d2d -rb0f90032367640dd22ddfbe0307a20cb6e931ceb
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision c230be1bd4296324bf5dfc288c212eb7c2ce5d2d)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision b0f90032367640dd22ddfbe0307a20cb6e931ceb)
@@ -81,7 +81,8 @@
 // ********** private function prototypes **********
 
 static BOOL sendTestAckResponseMsg( MSG_ID_T msgID, BOOL ack );
-static BOOL sendAckResponseMsg( MSG_ID_T msgID, COMM_BUFFER_T buffer, BOOL ack );
+static BOOL sendAckResponseMsg( MSG_ID_T msgID, COMM_BUFFER_T buffer, BOOL ack );
+static BOOL sendUIResponseMsg( MSG_ID_T msgID, BOOL accepted, U32 reason );
 
 /*********************************************************************//**
  * @brief
@@ -222,7 +223,39 @@
     return result;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The sendUIResponseMsg function constructs an UI response message for a
+ * handled UI message and queues it for transmit on the appropriate CAN channel.
+ * @details Inputs: none
+ * @details Outputs: response message constructed and queued for transmit.
+ * @param msgID ID of handled message that we are responding to
+ * @param accepted T/F - request accepted?
+ * @param reason reason code if rejected
+ * @return TRUE if response message successfully queued for transmit, FALSE if not
+ *************************************************************************/
+static BOOL sendUIResponseMsg( MSG_ID_T msgID, BOOL accepted, U32 reason )
+{
+    BOOL result;
+    MESSAGE_T msg;
+    UI_RESPONSE_PAYLOAD_T cmd;
 
+    cmd.accepted = accepted;
+    cmd.rejectionReason = reason;
+
+    // Create a message record
+    blankMessage( &msg );
+    msg.hdr.msgID = msgID;
+    msg.hdr.payloadLen = sizeof( UI_RESPONSE_PAYLOAD_T );
+    memcpy( &msg.payload, &cmd, sizeof( UI_RESPONSE_PAYLOAD_T ) );
+
+    // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
+    result = serializeMessage( msg, COMM_BUFFER_OUT_CAN_DG_2_UI, ACK_REQUIRED );
+
+    return result;
+}
+
+
 // ***********************************************************************
 // ***************** Message Sending Helper Functions ********************
 // ***********************************************************************
@@ -1685,7 +1718,79 @@
     sendAckResponseMsg( (MSG_ID_T)message->hdr.msgID, COMM_BUFFER_OUT_CAN_DG_2_HD, status );
 }
 
+/*********************************************************************//**
+ * @brief
+ * The handleSetROOnlyMode function handles the setting of the RO mode only.
+ * @details Inputs: none
+ * @details Outputs: message handled
+ * @param message a pointer to the message to handle
+ * @return none
+ *************************************************************************/
+void handleSetROOnlyMode( MESSAGE_T* message )
+{
+    REQUEST_REJECT_REASON_CODE_T rejReason = REQUEST_REJECT_REASON_DG_RO_ONLY_MODE_INVALID_PAYLOAD_LENGTH;
+    BOOL accepted                          = FALSE;
 
+    if ( message->hdr.payloadLen == sizeof(U32) )
+    {
+        U32 result;
+
+        rejReason = REQUEST_REJECT_REASON_NONE;
+
+        memcpy( &result, message->payload, sizeof(U32) );
+
+        if ( ( 0 == result ) || ( 1 == result ) )
+        {
+            switch ( getCurrentOperationMode() )
+            {
+                case DG_MODE_FAUL:
+                case DG_MODE_SERV:
+                case DG_MODE_INIT:
+                case DG_MODE_STAN:
+                    if ( TRUE == (BOOL)result )
+                    {
+                        enableROOnlyMode();
+                        accepted = TRUE;
+                    }
+                    break;
+
+                default:
+                    rejReason = REQUEST_REJECT_REASON_DG_RO_ONLY_MODE_DG_BUSY;
+                    break;
+            }
+        }
+        else
+        {
+            rejReason = REQUEST_REJECT_REASON_DG_RO_ONLY_MODE_INVALID_PARAMETER;
+        }
+    }
+
+    sendUIResponseMsg( MSG_ID_DG_RO_ONLY_MODE_STATUS_RESPONSE, accepted, rejReason );
+    sendAckResponseMsg( (MSG_ID_T)message->hdr.msgID, COMM_BUFFER_OUT_CAN_DG_2_UI, ACK_REQUIRED );
+}
+
+/*********************************************************************//**
+ * @brief
+ * The requestROOnlyModeStatusFromUI function handles the request
+ * the RO only mode status from UI.
+ * @details Inputs: none
+ * @details Outputs: message handled
+ * @return none
+ *************************************************************************/
+void requestROOnlyModeStatusFromUI( void )
+{
+    MESSAGE_T msg;
+
+    // Create a message record
+    blankMessage( &msg );
+    msg.hdr.msgID      = MSG_ID_DG_RO_ONLY_MODE_STATUS_REQUEST;
+    msg.hdr.payloadLen = 0;
+
+    // Serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
+    serializeMessage( msg, COMM_BUFFER_OUT_CAN_DG_2_UI, ACK_REQUIRED );
+}
+
+
 // ***********************************************************************
 // **************** Message Handling Helper Functions ********************
 // ***********************************************************************