1. Short pins 2 and 3 of the COM1/COM2 connector using a clip or similar tool, then enter the [Control Panel] from the [Menu Screen].
2. In the [Control Panel] menu, select the [Serial] menu.
3. In the serial window, select the signal level as RS-232C and run [Port Diagnosis].
4. A serial self-diagnosis window will pop up. If it displays [COM2, RS-232C: Communication, OK], the port is normal.
5. If, despite a proper short, it displays [COM2, RS-232C: Communication, Error], this indicates a hardware issue with the port. Please request A/S support from the customer service center.
 

Note:
Port diagnosis is different from [PLC Communication Diagnosis]. Port diagnosis is also called a loopback test and is used to check whether the hardware port is normal or faulty.
Communication diagnosis can be performed in the [Control Panel-PLC] menu on the menu screen.
For PLC communication, please refer to the relevant manual for cable wiring diagrams and communication settings.