# Modbus Tags / Manually Specify Each Address

**URL:** <https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [August 26, 2023, 6:04pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421 "2023-08-26T18:04:32Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Coleman\_Dudley](https://avatars.discourse-cdn.com/v4/letter/c/e0b2c6/32.png) [@Coleman\_Dudley](https://forum.inductiveautomation.com/u/Coleman_Dudley)\
**Post date:** [August 26, 2023, 6:04pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/1 "2023-08-26T18:04:32Z")

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Good Afternoon,

I'm still learning Ignition and I'm using a Modbus Device. I'm manually Specify Each Address, but I don't think I'm doing it correctly.

This is what I placed in the tag editor:

Name: Gateway  
Data Type:  
Integer  
OPC Server: Ignition OPC UA Server  
OPC Item Path: [PPS33LR]HRUS1.

Thanks,

C

[2023-08-24\_18-33-52 Modbus.pdf](https://forum.inductiveautomation.com/uploads/short-url/zbIyERZvQznxgqtExkMN20JKu27.pdf) (73.9 KB)

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**Author:** ![Ryan\_Allen](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ryan_allen/32/47013_2.png) [@Ryan\_Allen](https://forum.inductiveautomation.com/u/Ryan_Allen)\
**Post date:** [August 26, 2023, 6:39pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/2 "2023-08-26T18:39:53Z")

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You need to add the Modbus device in the gateway and then configure the addresses there as well

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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:** [August 26, 2023, 7:33pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/3 "2023-08-26T19:33:06Z")

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Try `[PPS33LR]1.HRUS1`

Since the docs say that the slave unit can be from 1-247, then Ignition's default slave ID of zero won't work. The above includes `1.` to specify slave unit #1.

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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:** [August 26, 2023, 7:34pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/4 "2023-08-26T19:34:33Z")

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> [@Ryan\_Allen](#):
>
> then configure the addresses there as well

No, you don't **need** to. The address mappings are entirely optional, and no longer recommended.

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<div class="post-metadata">

**Author:** ![Coleman\_Dudley](https://avatars.discourse-cdn.com/v4/letter/c/e0b2c6/32.png) [@Coleman\_Dudley](https://forum.inductiveautomation.com/u/Coleman_Dudley)\
**Post date:** [August 26, 2023, 8:15pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/5 "2023-08-26T20:15:24Z")

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pturmel,

Thanks for your response. I was looking at the Modbus Slave. This is the information that it displayed.

I think it should be:

[PPS33LR]8.HRUS1

C

[2023-08-26\_15-12-10.pdf](https://forum.inductiveautomation.com/uploads/short-url/j7NEN8BmVMYdodr6ghpSz0cHMwT.pdf) (6.0 KB)

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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:** [August 26, 2023, 10:51pm UTC](https://forum.inductiveautomation.com/t/modbus-tags-manually-specify-each-address/78421/6 "2023-08-26T22:51:18Z")

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Makes sense. Are you sure odd parity is correct? The default for Modbus RTU is E-8-1, that is, even parity.