PLC Fault- Ignition HMI

What could be done to show the tag error when PLC get fault. My PLC had a fault and it shuts all the equipment down but the tags on the Ignition HMI were tuck at its last position as “Running”. No tag errors, like a PLC down…
How can I solve this issue?

Monitor the quality of the tags to pick up connection breakage. Some drivers expose a diagnostic tag you can monitor. Otherwise, you might need a rolling counter or other heartbeat in your PLC that would indicated continued code execution.

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Is that necessary to have expression tag to check the quality and value? If not, how do we get the active tag, if it lost the quality?

An expression tag that extracts the quality from another tag is one method, yes. Quality is included in tag bindings, though, so it will automatically trigger overlay graphics where used.

I’m not sure what you mean, here.