Tag Historian - Rate issue

I'm on 8.1.22

Not sure if I missed something, I try to set history on a tag with a sample rate of 1 minutes. I use Power chart to display the history and export data to csv file, in my file i see that tag value is insert every 2sec.

I Also tried by used tag group and got same issue



The observed rate from a query will not be the same as the actual sample rate unless you're using 'Natural' aggregation mode in your history query. What does your history query/binding/etc look like?


I use PowerChart, it don't requier any binding to access data

Try setting the aggregate mode to LastValue? And/or try changing the point count property to -1.

Hoping to get a little clarity on this @PGriffith. Csv export will export all data points used to create the power chart plot? Or will the export contain all DB entries during the time range?
I guess we are confused as we are limiting power chart pointcount to 300 but getting 574 rows in the csv export. (Oddly in the export timestamps are duplicated every other row but have different data. There is a separate post already on that behavior so I only bring it up here in case it could be relevant).

That's normal for min/max aggregation.

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The 'Export' functionality in the menu on the power chart only exports the data that's currently loaded in the chart. You can look at the network traffic yourself and confirm that no additional request is made from the frontend when you do an export.

As Phil said - 'duplicate' entries with the same timestamp is expected for min/max aggregation, which is the default on the chart.