Missing Backfilled Data from Calculation (V25.5.0)
Good Day All! I have created 3 new tags from simple calculations. They are simply true or false based on whether a temperature value is above a threshold or not. I set the "Backfill Start Time" to a little over a year in the past. I see the 3 new tags in the historian tile and in Axiom but there is no historical or backfilled data. I may be misunderstanding how data backfilling works but I would expect to see these tags with TVQs back to a bit over a year ago. The calculation list shows there are over 100K "TVQs Since Start" I only have TVQs from the initial start of the calculation, no historical calculation results. I hope I am missing something because I would like to look back in the past. Thank you
3 replies
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Hi ,
If you are seeing the tags in the historian and Axiom then it's not buffering in SaF. Now, the historian is only going to store the TVQ's by exception. So if the calculation evaluates and it's the same value as it was before, there wouldn't be a new update in the historian. It would simply time extend until the value changed. Would you still expect to see more value changes? You should at least have an initial value at the beginning of where you backfilled to.
The other thing you could try is copying the calc and removing the old one to see if you get the same results when you backfill. You would need to make sure the old one is removed before initializing the new one. -
Hey Steve,
Thank you for the quick reply. I was able to figure things out. I assumed that backfilling would happen automatically when the calc was put in the live state, but no historical tag values were created until I selected the calc and clicked 'Backfill Selected Jobs." I now have the historical data I anticipated. Thanks again for your support. Have a great day.
Regards,
Tim
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