Historical Tag Recording Too Many Data Points

Gateway: Ignition Edge 8.1.12
Application: Perspective

The customer gutted an old system to set up a small test plant. There is no store and forward being used to a central server.

I have tags in the PLC that are only updating every hour on the hour (every o’clock). The customer is using the AdHocTrends chart to export data every day for personal logging purposes. One would expect the tags to record once every hour for a total of 24 data point a day. What is actually happening is multiple data points every hour. This requires a little more manual manipulation of the data the customer would prefer not to have to do.

The three tags in question are set up the same way in the designer. Am I not setting up the historical settings for these tags correctly, or is there a setting somewhere else that I am missing? The tags seem to record every 5 mins, but it’s not exact or the same every time. Changing minimum time between samples to something like 30 mins does not seem to affect the tag historization either.


Please show the history binding that is generating the data table. Ignition interpolates data to make it appear like continuous, periodic readings.

The AdHocTrends in the Ignition Exchange just uses the built in Powerchart

@Transistor’s reply sent down the path to a solution for what the customer wanted. I ended up using a Table and custom scripting to combine three tag history queries into one dataset to fill a table. Then a button to be able to download the table data to a csv file.

Good! Don’t forget to mark one of the answers as “Solution”.

Ultimately, the solution to access the correct tag history data was to use the script function system.tag.queryTagHistory. Another possible solution would be to use a Tag History Binding and the “AsStored” option.

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