# Using resistor resistance value in another block

**URL:** <https://forum.plexim.com/t/using-resistor-resistance-value-in-another-block/1251>\
**Category:** PLECS\
**Tags:** reading-value\
**Created:** [June 29, 2023, 7:07pm UTC](https://forum.plexim.com/t/using-resistor-resistance-value-in-another-block/1251 "2023-06-29T19:07:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![taydin](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@taydin](https://forum.plexim.com/u/taydin)\
**Post date:** [June 29, 2023, 7:07pm UTC](https://forum.plexim.com/t/using-resistor-resistance-value-in-another-block/1251/1 "2023-06-29T19:07:35Z")

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I have added a function block into my schematic which makes a calculation based on the value of a resistor in the schematic. Been looking at the manual, have gone through the forum, but I can’t find a way to refer to the resistor value. I tried R1, [R1], and other possibilities, but I’m always getting an error saying the variable is not defined. What is the correct way to do this?

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**Author:** ![Kris\_Eberle](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/kris_eberle/32/6_2.png) [@Kris\_Eberle](https://forum.plexim.com/u/Kris_Eberle)\
**Post date:** [June 29, 2023, 7:40pm UTC](https://forum.plexim.com/t/using-resistor-resistance-value-in-another-block/1251/2 "2023-06-29T19:40:10Z")

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You would need to define the resistance value by a variable, e.g., R = 1;, in the initialization command window of the Simulation Parameters Window (from the Simulation menu). Then, the R variable could be used elsewhere and you would have consistent values for all instances.