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Unexplained entries in PI Archive

Question asked by maguirej on Dec 16, 2016
Latest reply on Dec 20, 2016 by maguirej

Hi Guys,


I have a problem with intermittent erroneous entries in a PI archive. The PI Server is being supplied tag values from our OPC via the PI Collector Interface.

For different tags at different times we are getting these erroneous entries in the archive every so often.

I have debug mode enabled in the PI Interface configuration tool which is logging tag activity as it is read from the OPC Server. It shows that theses erroneous

entries are not coming from the Interface or indeed the OPC.


The strange thing is that these erroneous entries, although happening at random times, follow a pattern.


Sometimes, when the PI Archive logs a legitimate tag status (eg. "OFF"), it will almost immediately (in approx 20 milliseconds) log it's previous state (eg. "ON").

Then strangely after exactly 20 minutes it will log the tag status as "OFF".


The PI Archive is supplying PI Batch with data. The problem is PI Batch doesn't see the legitimate OFF as it is almost immediately followed by the erroneous ON state in the archive.

PI Batch will however see the erroneous OFF  entry 20 minutes later and use that as the OFF entry for the tag.


I'm not sure how to faultfind this any further. As I've stated, the OPC or PI Interface are not supplying these stray entries.


Have any of you guys seen anything like this before or know what I else I could check to figure this problem out?


Hope this makes sense!


Thanks in advance.