Alarm on Device Connection Status

Say I have a tag from an OPC device and the device is unreachable which could be caused by power outage, network outage or other unforeseeable factors. And the Quality of the tag is bad.

Of course I can set up an alarm on the particular tag and get a notification when the quality is bad, but I don’t feel it is the right approach for monitoring device failure.

I am trying to set an alarm on the System Tag
Gateway > Devices > {Device Name} → Status
But it is not working as I would expect.

I believe this is a general and common problem and wondering how would you get a notification when a device is not reachable.

We use a rolling number in the PLC and then use the hasChanged expression and drive an alarm if it hasn’t changed.

Specifically for ControlLogix we use the timestamp LINT.

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What I just did was change the “Alarm Type” to “On Condition” then write an expression. I used {[.]Status}!=“Connected”