OPC UA | Omron NJ Driver | PLC | connection status tag

I am trying to figure out how to make a connection status process that continually checks to see if the plc is connected to the ignition server. I would like for a plc variable to change states based on connection status. The issue I am running into is that once the ethernet cable is unplugged from the PLC, I cannot change the state of that variable from ignition since there is no coms. I simply just need a state change to take place on a variable in the PLC when connection from the plc to the ignition server changes.

Is there a connection status system tag I can target on the ignition that will write to the plc when the connection is defective?

No, but you can make your own "heartbeat". Simply allocate a pair of tags in the PLC (integers, perhaps) for this purpose, and use a timer event in Ignition to increment one of them on some reasonable pace. Have a rung in the PLC that compares them, and when different, copies the new value to the other and restarts a timer. If the timer expires, your comms are down. I usually use a timeout 2½ times the increment period.

This approach is not specific to Omron NJ/NX processors--it works with everything that uses a polling driver.

1 Like