[Cause]
The PLC may be in test mode or program mode, and the PLC has stopped its connection with this robot. The severity of this alarm is set to WARN or STOP on the AB-RIO setup screen. The latest-state setting on the same screen also affects the input state when I/O is not being transmitted or received.
[Countermeasure]
Check the PLC settings and confirm that the PLC is in run mode and that its connection with this robot has not been stopped.