Mitsubishi Electric FR-A7NP Instruction Manual page 36

INVERTER SETTING
(2) Measures at alarm occurrences
Alarm Indication Alarm Definition
Communication line
E.OP1, E.OP3
error
E.1, E.2, E.3 Option alarm
When alarms other than the above are displayed, refer to the inverter manual and remove the cause of the alarm.
30
Check the LED status of the option unit and remove the cause of the
alarm. (Refer to page 4 for LED indication status)
Check the other nodes on the network.
Inspect the master.
Check the connection between the inverter and option unit for poor
contact, etc. and remove the cause of the error.
For the FR-A700 series, fit the communication option in the option
connector 3.
Measures