# Opc tag value change

**URL:** <https://forum.inductiveautomation.com/t/opc-tag-value-change/34167>\
**Category:** Ignition\
**Created:** [April 23, 2020, 4:51pm UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167 "2020-04-23T16:51:39Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Oleh](https://avatars.discourse-cdn.com/v4/letter/o/b4bc9f/32.png) [@Oleh](https://forum.inductiveautomation.com/u/Oleh)\
**Post date:** [April 23, 2020, 4:51pm UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167/1 "2020-04-23T16:51:39Z")

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Hello. How can I adjust the value of an opc tag without a script and expression tag?. For example, the tag value-15.

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [April 23, 2020, 7:07pm UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167/2 "2020-04-23T19:07:47Z")

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If you just need to adjust the value for the purpose of displaying it in some component, e.g. a numerical label, you can use an expression binding and adjust the value using arithmetic in the binding:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/2X/9/912c37833d0c810ce6068e751e0fb09693542872.jpeg)

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [April 23, 2020, 8:09pm UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167/3 "2020-04-23T20:09:13Z")

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Linear scaling can do it if you want the effect to apply everywhere.

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<div class="post-metadata">

**Author:** ![Oleh](https://avatars.discourse-cdn.com/v4/letter/o/b4bc9f/32.png) [@Oleh](https://forum.inductiveautomation.com/u/Oleh)\
**Post date:** [April 24, 2020, 8:03pm UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167/4 "2020-04-24T20:03:15Z")

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Help me please. I don’t understand how to configure linear tag scaling. My default tag value from the controller is 127.5, I need to subtract 0.13 from this value to get 127.37. What parameters should I set for RW, RL, SH, SL?

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**Author:** ![AlThePal](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/althepal/32/3603_2.png) [@AlThePal](https://forum.inductiveautomation.com/u/AlThePal)\
**Post date:** [April 25, 2020, 10:37am UTC](https://forum.inductiveautomation.com/t/opc-tag-value-change/34167/5 "2020-04-25T10:37:51Z")

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If you want to subtract a fixed value of 0.13 using linear tag scaling, do the following:

1. Open the Tag Editor for the OPC tag and display the Numeric tab
2. Set the Scale Mode to Linear
3. Set the Raw Low and High values to the minimum and maximum possible values of your input e.g. 0 and 100
4. Set the Scaled Low and High values to these value minus 0.13 i.e. (0 - 0.13) and (100 - 0.13)

Your value should now have 0.13 subtracted from its raw value every time it changes. You can check this by displaying its value next to an OPC tag reading from the same input but without any scaling.