# Boolean values from modicon OPC UA PLC are logged in historian core strangely **URL:** \ **Category:** Ignition\ **Tags:** support, ignition83\ **Created:** [February 14, 2026, 5:27am UTC](https://forum.inductiveautomation.com/t/boolean-values-from-modicon-opc-ua-plc-are-logged-in-historian-core-strangely/113974 "2026-02-14T05:27:22Z")\ **Posts on this page:** 1\ **Showing post:** 4
**Author:** ![Matrix\_Engineering](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/matrix_engineering/32/19781_2.png) [@Matrix\_Engineering](https://forum.inductiveautomation.com/u/Matrix_Engineering)\ **Post date:** [February 14, 2026, 5:31pm UTC](https://forum.inductiveautomation.com/t/boolean-values-from-modicon-opc-ua-plc-are-logged-in-historian-core-strangely/113974/4 "2026-02-14T17:31:02Z")
Welcome! Some further insight for you: > [@I’m trying to understand the recommended best practices for configuring Ignition Tag History, specifically how the following pieces are intended to work together](https://forum.inductiveautomation.com/t/i-m-trying-to-understand-the-recommended-best-practices-for-configuring-ignition-tag-history-specifically-how-the-following-pieces-are-intended-to-work-together/113583): > > • Tag Group (normal execution rate) • Historical Tag Group (e.g. Default Historical) • Sample Mode (Tag Group vs On Change vs Periodic) • Deadband Style (Auto vs Analog vs Discrete) I understand that the Tag Group controls how often the tag is evaluated/read, while the Historical Tag Group controls how often the historian evaluates whether a sample should be stored. However, it’s not entirely clear when it is best to reuse existing tag groups versus creating a dedicated Historical Tag Group,… --- _[View the full topic](https://forum.inductiveautomation.com/t/boolean-values-from-modicon-opc-ua-plc-are-logged-in-historian-core-strangely/113974)._