Cause : CANopen heartbeat error comes when CANopen Heartbeat detects that one of the slaves does not respond, the ChbE fault occurs. The upper unit sets the confirming time of producer and consumer during configuration.

1. Increase heartbeat time (Index 100C).
2. Verify the wiring and grounding of the communication circuit.
3. Make sure the communication circuit is wired in series. 
4. Use CANopen cable or add terminating resistance.
5. Check or replace the communication cable.