CANopen Communication Module DVPCOPM-SL DVP-PLC Operation Manual 48 Code Indication How to correct FB The sending buffer in DVPCOPM-SL is full. Make sure the bus works normally and repower DVPCOPM-SL. FC The receiving buffer in DVPCOPM-SL is full. Check if the bus cables in CANopen network are connected properly and repower DVPCOPM-SL.