# Strange Modbus Device Address Format

**URL:** <https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975>\
**Category:** Ignition\
**Created:** [October 3, 2023, 2:15pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975 "2023-10-03T14:15:53Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![brandon1](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@brandon1](https://forum.inductiveautomation.com/u/brandon1)\
**Post date:** [October 3, 2023, 2:15pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975/1 "2023-10-03T14:15:53Z")

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Hey Everyone,

I have run across a project that has the following OPC Item Path:

**[PLCLP,bit=12]39.HR2**

This seems to work in production but is not working during my testing in development after migrating from 7.9 to 8.1.

Is this equivalent to **[PLCLP]39.HR2.12**

Thanks

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**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:** [October 3, 2023, 2:19pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975/2 "2023-10-03T14:19:23Z")

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> [@brandon1](#):
>
> Is this equivalent to **[PLCLP]39.HR2.12**

Yes.

The former syntax was something supported a looonnnnng time ago but eventually dropped... this system must have been around a while.

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<div class="post-metadata">

**Author:** ![brandon1](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@brandon1](https://forum.inductiveautomation.com/u/brandon1)\
**Post date:** [October 3, 2023, 2:24pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975/3 "2023-10-03T14:24:29Z")

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Yes this system was originally 7.8 and moved to 7.9 and now I'm working on the move to 8.1

Just to confirm this syntax will not work in 8.1?

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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:** [October 3, 2023, 2:25pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975/4 "2023-10-03T14:25:01Z")

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> [@brandon1](#):
>
> Just to confirm this syntax will not work in 8.1?

Yes, any tags using this OPC Item Path syntax will need to be updated.

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<div class="post-metadata">

**Author:** ![brandon1](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@brandon1](https://forum.inductiveautomation.com/u/brandon1)\
**Post date:** [October 3, 2023, 2:25pm UTC](https://forum.inductiveautomation.com/t/strange-modbus-device-address-format/79975/5 "2023-10-03T14:25:48Z")

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Okay thanks for the quick reply Kevin!

Good thing this is not used a lot in the project. 😅