OPC Collector receives Bad when OPC Server shows Good
I have an issue where the OPC Collector is showing No Data even though the OPC server shows Good data. The value in the Historian maintains, but the View will show Empty. The Value in the OPC server does not change frequently, so the value in the OPC server showing Good is the same value that is showing in the Historian as No Data. I am assuming because the value is not changing the Historian is not changing, but I would think the quality change should pick up. A quick solution is to stop and restart the OPC collector (and this does work), however this happens frequently enough that is something that would need to be monitored regularly.
Is there a setting that can control that when the quality value changes, the Historian will log that?
Here you can see the Historian captured No Data, but maintained the value
Here you can see the View captured No Data, and Empty as the Value
Here you can see the OPC Server is showing the value as Good
There are other values within this group that maintain the Good reading, so it is not an issue with the Group.
Any ideas greatly appreciated
1 reply
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Hey erice,
I have the same thing going on with OPC data, particularly data that doesn't change very often, like machine status bits or setpoints. From what I have discovered, the historian checks the timestamp from the source, and if the timestamp is duplicate, which it would be if it hadn't changed, then it will flag it as bad and Axiom will display it as "NoData." Not an ideal fix but more of a band aid, you can go into the events/calcs and do what I call a "quality override" statement and create a new tag based on the same data.....
There is a problem with this approach, if you're data is no good then it will display the last good value as if nothing was wrong. For my purposes though, it's totally fine. Good luck and hopefully this issue is addressed in the future.
Regards,
Tim
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