Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -red962b050e6b9714318a0b9034742efc2ccb9e4f -r2f2419f67d9d458837893fef5cc1b21870021026
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision ed962b050e6b9714318a0b9034742efc2ccb9e4f)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 2f2419f67d9d458837893fef5cc1b21870021026)
@@ -781,11 +781,12 @@
  * The sendDGFillCommand function constructs a DG fill command message
  * and queues the msg for transmit on the appropriate CAN channel.
  * @details Inputs: none
- * @details Outputs: DG fill command msg constructed and queued.
+ * @details Outputs: DG fill command msg constructed and queued.
+ * @param cmd start or stop fill command
  * @param fillToVolumeMl volume (in mL) to fill inactive reservoir to
  * @return TRUE if msg successfully queued for transmit, FALSE if not
  *************************************************************************/
-BOOL sendDGFillCommand( U32 fillToVolumeMl )
+BOOL sendDGFillCommand( U32 cmd, U32 fillToVolumeMl )
 {
     BOOL result;
     MESSAGE_T msg;
@@ -794,10 +795,12 @@
     // Create a message record
     blankMessage( &msg );
     msg.hdr.msgID = MSG_ID_DG_FILL_CMD;
-    msg.hdr.payloadLen = sizeof( U32 );
+    msg.hdr.payloadLen = sizeof( U32 ) + sizeof( U32 );
+
+    memcpy( payloadPtr, &fillToVolumeMl, sizeof( U32 ) );
+    payloadPtr += sizeof( U32 );
+    memcpy( payloadPtr, &cmd, sizeof( U32 ) );
 
-    memcpy( payloadPtr, &fillToVolumeMl, sizeof( U32 ) );
-
     // 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_HD_2_DG, ACK_REQUIRED );