Cause : Communication option fault comes when the inverter trips if a communication line error occurs in the communication option.

1. Check for an incorrect option function setting and operation.
2. Check that the plug-in option is plugged into the connector properly.
3. Check for a break in the communication cable.
4. Check that the terminating resistor is fitted properly.
5. Check the option function setting, etc.
6. Connect the plug-in option securely.