# Plc tag value at current time subtracted from PLC tag value 24 hours ago = new tag value

**URL:** <https://forum.inductiveautomation.com/t/plc-tag-value-at-current-time-subtracted-from-plc-tag-value-24-hours-ago-new-tag-value/93613>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [July 23, 2024, 4:33pm UTC](https://forum.inductiveautomation.com/t/plc-tag-value-at-current-time-subtracted-from-plc-tag-value-24-hours-ago-new-tag-value/93613 "2024-07-23T16:33:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![fivecents](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@fivecents](https://forum.inductiveautomation.com/u/fivecents)\
**Post date:** [July 23, 2024, 4:33pm UTC](https://forum.inductiveautomation.com/t/plc-tag-value-at-current-time-subtracted-from-plc-tag-value-24-hours-ago-new-tag-value/93613/1 "2024-07-23T16:33:17Z")

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We have history enabled but it isn't clear to me what method to use to get new tag.

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**Author:** ![Jack\_Jones](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@Jack\_Jones](https://forum.inductiveautomation.com/u/Jack_Jones)\
**Post date:** [July 23, 2024, 5:42pm UTC](https://forum.inductiveautomation.com/t/plc-tag-value-at-current-time-subtracted-from-plc-tag-value-24-hours-ago-new-tag-value/93613/2 "2024-07-23T17:42:57Z")

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Here's a [link](https://www.docs.inductiveautomation.com/docs/8.1/ignition-modules/reporting/report-data/tag-historian-query) to what I used for a similar case.

This allows you to query the tags history directly within the report.