No scan class information found for tags. warning

I was logged onto a customer installation today and noticed the following error repeating in the console:

2012-05-10 10:16:04 AM SQL2008R2_Loader (id=4991fc7a) No scan class information found for tags. All returned data will be bad quality.

This was occurring every 5 seconds since around 10:15 am from the previous day. I opened the default Ignition Realtime SQLTags Provider configuration screen, clicked save and the problem went away. As far as I can tell there was no negative impact on system operation related to the message, but the warning concerned me.

This customer is running version 7.2.4 (b953). I have attached an export of the logs.

Any information you can provide on this? Should we be concerned?

logs.bin.gz (689 KB)


That message is from the tag history query system. I doubt that editing the realtime tag provider actually affected it, but you may have closed a client, or changed screens, around the same time.

Basically, something was running a query every 5 seconds that was querying incomplete data. Besides the results of that query not being what you might want, it would have no impact on the system. This message could be caused by a misalignment between the tag info and scan class tables (like, a tag was assigned to a scan class, but the scan class info doesn’t exist for some reason), or perhaps a query that is not asking for any tags (maybe a query asking for time before any tags were added?).

At any rate, not really anything to worry about. If it starts happening again, you can go to Console>Levels, and turn “History.SQLTags” to DEBUG. Let it run for a few minutes, turn it back to INFO, and upload that log. That will let us see the actual parameters of the query that is causing the message, which might help you track it down in the window.