# Nested UDT error

**URL:** <https://forum.inductiveautomation.com/t/nested-udt-error/93008>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [July 10, 2024, 1:18pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008 "2024-07-10T13:18:25Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Anant\_Upadhyayula](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Anant\_Upadhyayula](https://forum.inductiveautomation.com/u/Anant_Upadhyayula)\
**Post date:** [July 10, 2024, 1:18pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008/1 "2024-07-10T13:18:25Z")

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![Parentudt](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/8/589fe33abf5ac232f37799446a57d3bdb38b17ac.png)  
I am getting error as shown in the image. Here is the setup.

1. Parent udt contains 3 child udts. and 2 parameters.
2. Each child udt has 2 or 3 parameters.
3. Some child udt has memory, expression and OPC tags.

am I doing something wrong with this setup?

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**Author:** ![bschroeder](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bschroeder/32/13260_2.png) [@bschroeder](https://forum.inductiveautomation.com/u/bschroeder)\
**Post date:** [July 10, 2024, 1:28pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008/2 "2024-07-10T13:28:51Z")

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Nothing wrong with the setup.

For the child UDTs, yes they can have their own parameters. You set those parameters by drilling down to them in the tag instance and setting them there.

The error is probably because of the tag configuration. Are those OPC tags?

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<div class="post-metadata">

**Author:** ![Anant\_Upadhyayula](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Anant\_Upadhyayula](https://forum.inductiveautomation.com/u/Anant_Upadhyayula)\
**Post date:** [July 10, 2024, 1:30pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008/3 "2024-07-10T13:30:22Z")

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everything under \_edge\_PLC are OPC and everything under current are loopup from datasource.

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<div class="post-metadata">

**Author:** ![bschroeder](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bschroeder/32/13260_2.png) [@bschroeder](https://forum.inductiveautomation.com/u/bschroeder)\
**Post date:** [July 10, 2024, 1:35pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008/4 "2024-07-10T13:35:33Z")

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For the OPC tags... you will need to investigate your OPC address and make sure that you are setting them correctly via the parameters.

Same with the expression tags.

Once you have created the tag instance, check the individual tag diagnostics to see what is going on.

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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:** [July 10, 2024, 1:39pm UTC](https://forum.inductiveautomation.com/t/nested-udt-error/93008/5 "2024-07-10T13:39:46Z")

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In the outer definition, provide parameters that can be used to compute or pass through values to the nested UDTs. Use bindings at the nested parameter to reference the outer parameter. Then, when making instances of the outer UDT, the nested UDTs will get appropriate parameter values.

For least confusion, avoid using identical parameter names across many UDTs. Consider using the UDT names as parameter name prefixes.