What Are Tag Aggregates in SystemLink?

Updated May 25, 2022

Reported In

Software

  • SystemLink Server

Issue Details

I noticed that there is a checkbox for aggregate values in the Tag Details section in SystemLink Server. What is the purpose of these values?

Solution

The aggregate values are buffered sets of values that store the previous states or values of a given tag. These are used to run statistic functions and provide this information to the end user. The specific statistic values included are the minimum and maximum, the mean, and the current count of the historical tag value. Here is an example for reference:
 
Tag aggregates
 
 
 

Additional Information

If the Aggregate Values checkbox isn't checked, then SystemLink won't keep track of historical tag values. It will just reserve memory space for the current tag value, which continually overwrites the previous value at each client update. Users can also set the size of the aggregate value buffer in the tag configuration using the Retention parameter with the different options duration, count, or permanent. 

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