# UDT instance is no longer able to run and expression on another UDT instance in the same tag folder?

**URL:** <https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494>\
**Category:** Ignition Early Access\
**Created:** [October 29, 2019, 6:43pm UTC](https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494 "2019-10-29T18:43:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![clintag](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@clintag](https://forum.inductiveautomation.com/u/clintag)\
**Post date:** [October 29, 2019, 6:43pm UTC](https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494/1 "2019-10-29T18:43:35Z")

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In 7.9.2 I had a UDT instance that contained Long Integer Modbus registers that contained packed alarm bits in them for things like digital input alarm bits. In another UDT instance I would run an expression to break out individual bits for alarming purposes. I did this by using parameters of the UDT in the expression that provided the UDT with the path to the packed bit UDT, register within it and the bit number I was interested in retrieving from that register. This worked fine until i upgraded the project to V8.0.5. Any idea why this would have stopped functioning?  
The expression is shown below. It used the “Path\_To\_DI\_Alarm\_Bits” parameter which contained the full path the the tag folder, the UDT name and register within the folder. The second part “({DI\_Number}-1)” is another parameter of the UDT to specify which bit I wanted.  
getBit({Path\_To\_DI\_Alarm\_Bits},({DI\_Number}-1))

Clint

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**Author:** ![awalker](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/awalker/32/6874_2.png) [@awalker](https://forum.inductiveautomation.com/u/awalker)\
**Post date:** [November 6, 2019, 11:59pm UTC](https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494/2 "2019-11-06T23:59:46Z")

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Hi @clintag

Have you noticed any errors in the gateway?  
And are you able to send us a tag export?

Thanks!

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**Author:** ![clintag](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@clintag](https://forum.inductiveautomation.com/u/clintag)\
**Post date:** [November 7, 2019, 3:32pm UTC](https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494/3 "2019-11-07T15:32:44Z")

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I had not checked the Gateway logs. The error in the diagnostics in 8.0.5 on the expression is “[null, Error\_ExpressionEval(“Error trying to coerce ‘null’ to a number.”), Mon Nov 04 08:01:11 CST 2019 (1572876071060)]” I do not get this error in 7.9.7 (in my original post, I mistakenly said the working project is 7.9.2).

I have attached the UDT Data Types and Instances being used in the projects for 7.9.7 and 8.0.5

[AI\_UDT\_DataType\_7-9-7.xml](https://us1.discourse-cdn.com/inductiveautomation/original/2X/5/531e701f36d23d9fdaea8ae7556d151357302fe4.xml) (8.0 KB)  
[AI\_UDT\_DataType\_8-0-5.xml](https://us1.discourse-cdn.com/inductiveautomation/original/2X/a/a4b18a55a4d9503879486aad97a6b14ad55b39e5.xml) (15.1 KB)  
[UDT\_tag\_Instances\_7-9-7.xml](https://us1.discourse-cdn.com/inductiveautomation/original/2X/7/7a19355646271fd3849458db948f87fee18a8cd5.xml) (3.4 KB)  
[UDT\_tag\_Instances\_8-0-5.xml](https://us1.discourse-cdn.com/inductiveautomation/original/2X/d/dbdb7b04e98dc847517685beceb53b0bb7db9cae.xml) (4.8 KB)

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<div class="post-metadata">

**Author:** ![clintag](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@clintag](https://forum.inductiveautomation.com/u/clintag)\
**Post date:** [August 3, 2020, 2:30pm UTC](https://forum.inductiveautomation.com/t/udt-instance-is-no-longer-able-to-run-and-expression-on-another-udt-instance-in-the-same-tag-folder/29494/4 "2020-08-03T14:30:13Z")

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Hello,

I never heard back on this issue and am revisiting upgrading a customer but cannot due to this issue. I have a few customers that will have this issue if they try to upgrade and it affects huge parts of their projects.

Thanks,  
Clint