# Can an Expression Tag pass a reference to itself in a script?

**URL:** <https://forum.inductiveautomation.com/t/can-an-expression-tag-pass-a-reference-to-itself-in-a-script/40923>\
**Category:** Ignition\
**Created:** [November 24, 2020, 2:43pm UTC](https://forum.inductiveautomation.com/t/can-an-expression-tag-pass-a-reference-to-itself-in-a-script/40923 "2020-11-24T14:43:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![craigl](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/craigl/32/5010_2.png) [@craigl](https://forum.inductiveautomation.com/u/craigl)\
**Post date:** [November 24, 2020, 2:43pm UTC](https://forum.inductiveautomation.com/t/can-an-expression-tag-pass-a-reference-to-itself-in-a-script/40923/1 "2020-11-24T14:43:48Z")

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I want to have an expression tag run a script to check the health of a machine, but I don’t want to have to pass the tag path from each tag. Is there a way to pass in ‘this’ tag path?

What I have now is:  
runScript(“shared.util.calc.SlowCheck(’[default]machines/Printers/7301/’”)

I’d rather create a UDT with an expression tag that gets populated into each new instance that is effectively:  
runScript(“shared.util.calc.SlowCheck(this)”)

Am I overlooking an easy way to do that?

Thanks!!

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**Author:** ![zacht](https://avatars.discourse-cdn.com/v4/letter/z/ea5d25/32.png) [@zacht](https://forum.inductiveautomation.com/u/zacht)\
**Post date:** [November 24, 2020, 3:24pm UTC](https://forum.inductiveautomation.com/t/can-an-expression-tag-pass-a-reference-to-itself-in-a-script/40923/2 "2020-11-24T15:24:24Z")

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This table from [documentation](https://docs.inductiveautomation.com/display/DOC81/Tag+Paths) might help.

![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/a/1a386ebc9b96a8d9189a2b6f2834d3e015b9ab29.png)

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<div class="post-metadata">

**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\
**Post date:** [November 24, 2020, 3:48pm UTC](https://forum.inductiveautomation.com/t/can-an-expression-tag-pass-a-reference-to-itself-in-a-script/40923/3 "2020-11-24T15:48:53Z")

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In addition, UDTs have a few “meta” parameters automatically defined:  
[https://docs.inductiveautomation.com/display/DOC81/UDT+Parameters#UDTParameters-Pre-DefinedParameters](https://docs.inductiveautomation.com/display/DOC81/UDT+Parameters#UDTParameters-Pre-DefinedParameters)

| Parameter Name | Description |
| --- | --- |
| `{InstanceName}` | The name of the UDT Instance that this Tag is inside. |
| `{PathToParentFolder}` | The full path to the folder that this Tag is in. |
| `{PathToTag}` | The full path to the Tag using this parameter. |
| `{TagName}` | The name of the Tag that is using this parameter. |