@pcr the paneldue doesn't refresh the status automatically?

I have two HC-05 Buletooth module，I want to use them to replace the wire between the PanelDUE and the main board.Wow，It works very well.
But when I shutdown the mainboard,the paneldue still in standby mode，not the connecting mode.There is no heartbeat between The paneldue and the mainboard? Thanks.