Table Of Contents

Tag Historian Functions

Last Modified: November 14, 2019

Retain historical tag values to review, troubleshoot, or analyze data over time.


The 19.5 Tag Historian API does not work with 19.6 SystemLink Server or later. However, the 19.6 Tag Historian API works with all versions of SystemLink as well as the 19.5 Tag Historian API.

Configure Tag History Window

Defines the range of historical tag values to read with Read Tag History or Multi Read Tag History.

Read Tag History

Returns the historical values from a single tag. The data type of the tag must match the polymorphic instance.

Multi Read History

Returns the historical values from multiple tags in a single operation.

Configure Retention

Defines how long a tag retains historical values.

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