# Help fixing my Expression Tag

**URL:** <https://forum.inductiveautomation.com/t/help-fixing-my-expression-tag/83932>\
**Category:** Ignition\
**Created:** [January 8, 2024, 5:58pm UTC](https://forum.inductiveautomation.com/t/help-fixing-my-expression-tag/83932 "2024-01-08T17:58:26Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Jared\_Kossler](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@Jared\_Kossler](https://forum.inductiveautomation.com/u/Jared_Kossler)\
**Post date:** [January 8, 2024, 5:58pm UTC](https://forum.inductiveautomation.com/t/help-fixing-my-expression-tag/83932/1 "2024-01-08T17:58:26Z")

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I am using an expression tag to self increment. This is to track Kilowatt hours used on a specific machine in a factory. I am using the following expression: {[.]200 Hp kWh}+{[.]200 Hp kWh Net}

This has a had mixed results. I wrote 0 into the tag so it wouldn't be trying to add null. I have some tags that are working and others that even when I set its value to 0 its stays null.

Is there a better way to do this? or a way to fix what I have?

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**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [January 8, 2024, 6:25pm UTC](https://forum.inductiveautomation.com/t/help-fixing-my-expression-tag/83932/2 "2024-01-08T18:25:46Z")

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You can't use an expression tag to write to itself (assuming I'm reading your post correctly).

There are various threads on here about totalizers. Perhaps start here:

> [@Ignition totalizer for flow meter](https://forum.inductiveautomation.com/t/ignition-totalizer-for-flow-meter/54953):
>
> Due to PLC insufficient memory, I will have to totalize the flows on Ignition. I found that I can use Hour Meter, but it’s insufficient for my purpose. Totalizing the flow starting on specific time of the day. Pause the totalizing if condition A is off, continue if condition A is On. Reset totalizer at specific time of the day, before resetting the totalizer, move the current totalizer value to previous totalizer value, meanwhile also add the current totalizer value to lifetime totalizer valu…