# UDT writing fails

**URL:** <https://forum.inductiveautomation.com/t/udt-writing-fails/33607>\
**Category:** Ignition\
**Tags:** ignition80\
**Created:** [April 1, 2020, 8:20pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607 "2020-04-01T20:20:47Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![emjaimar](https://avatars.discourse-cdn.com/v4/letter/e/6bbea6/32.png) [@emjaimar](https://forum.inductiveautomation.com/u/emjaimar)\
**Post date:** [April 1, 2020, 8:20pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/1 "2020-04-01T20:20:47Z")

</div>

I have an UDT which I try to write to with a scrip on a button but it fails no mater what I try.

```auto
server = 'Ignition OPC UA Server'
path = 'ns=1;s=[PAXTest]AI01/Cfg_HiLim'
value = 65
system.opc.writeValue(server, path, value)

```

but it works perfectly with a regular tag

```auto
path = 'ns=1;s=[PAXTest]MyInt'

```

what am I overlooking?

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [April 1, 2020, 8:30pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/2 "2020-04-01T20:30:07Z")

</div>

Can you set the logging level for `drivers.LogixDriver.Requests.WriteTagsRequest` to DEBUG and then see if there are any errors in the gateway logs?

[https://docs.inductiveautomation.com/display/DOC80/Gateway+Diagnostics#GatewayDiagnostics-Logs](https://docs.inductiveautomation.com/display/DOC80/Gateway+Diagnostics#GatewayDiagnostics-Logs)

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<div class="post-metadata">

**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:** [April 1, 2020, 8:32pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/3 "2020-04-01T20:32:58Z")

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What kind of device is this? I’d expect a dot instead of a slash in the brands I usually use.

Or are you confusing Ignition tags with OPC items that represent device tags?

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<div class="post-metadata">

**Author:** ![emjaimar](https://avatars.discourse-cdn.com/v4/letter/e/6bbea6/32.png) [@emjaimar](https://forum.inductiveautomation.com/u/emjaimar)\
**Post date:** [April 1, 2020, 8:39pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/4 "2020-04-01T20:39:05Z")

</div>

yeah, that was my confusion, I tried with system.tag.writeBlocking at not avail then switched to OPC but not knowing I needed to change to dots

Thanks! Much apreciated

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [April 1, 2020, 8:41pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/5 "2020-04-01T20:41:33Z")

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So just to clear things up, system.opc.writeValue expects an OPC Item Path, which is derived from the NodeId assigned by the OPC server. The path is automatically assigned to an OPC tag when you drag and drop it from the browser. Most server/driver combos will have predictable NodeIds that let you guess or assign it manually, but you need to know that syntax ahead of time.

system.tag.writeBlocking expects the Tag Path to a tag, which is derived from its position in the Ignition tag model that you created it at at.

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<div class="post-metadata">

**Author:** ![emjaimar](https://avatars.discourse-cdn.com/v4/letter/e/6bbea6/32.png) [@emjaimar](https://forum.inductiveautomation.com/u/emjaimar)\
**Post date:** [April 1, 2020, 8:55pm UTC](https://forum.inductiveautomation.com/t/udt-writing-fails/33607/6 "2020-04-01T20:55:56Z")

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Thanks Kevin, now I know, still on my learning curve 😉