# Modbus TCP Device Issue

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667>\
**Category:** Ignition\
**Created:** [August 12, 2020, 10:13pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667 "2020-08-12T22:13:48Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![dion.botha](https://avatars.discourse-cdn.com/v4/letter/d/46a35a/32.png) [@dion.botha](https://forum.inductiveautomation.com/u/dion.botha)\
**Post date:** [August 12, 2020, 10:13pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667/1 "2020-08-12T22:13:48Z")

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Hi Guys,

I connected a Comet P8641 (Modbus TCP 4 channel temperature monitoring unit) to my desktop PC on a local network and was able to add the device to a trial version of Ignition I have running on my desktop.

I then added all the tags and was getting values.

I then disconnected it from my local network, connected it to our automation network (which has a bunch of Modbus TCP devices communicating happily through port 502), added it to our gateway (status says connected and I can ping it) and copied and pasted all the tags from my local Ignition to our corporate one.

Unfortunately all the tags’ quality is ‘Uncertain\_InitialValue’…

Any ideas?

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**Author:** ![dion.botha](https://avatars.discourse-cdn.com/v4/letter/d/46a35a/32.png) [@dion.botha](https://forum.inductiveautomation.com/u/dion.botha)\
**Post date:** [August 13, 2020, 4:26pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667/2 "2020-08-13T16:26:19Z")

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My colleague took a look and instead of adding tags via the designer tag browser he added a tag to the OPC Server via the gateway → OPC UA → Device Connections → {Device} → More → Addresses

Not working tag (added through designer tag browser):

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/0/e0584ed40820a04c3e20cb6c8a477d987b02579e.png)

Working tag:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/3/8342cc9d7a5089ab4a29c1a333495be8fdd7b339.png)

As you can see they are configured identically.

I believe he has discovered a bug and a work around - just thought I would share.

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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:** [August 13, 2020, 4:27pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667/3 "2020-08-13T16:27:05Z")

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The OPC Server name is different.

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<div class="post-metadata">

**Author:** ![dion.botha](https://avatars.discourse-cdn.com/v4/letter/d/46a35a/32.png) [@dion.botha](https://forum.inductiveautomation.com/u/dion.botha)\
**Post date:** [August 13, 2020, 4:28pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667/4 "2020-08-13T16:28:57Z")

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Ahhhhh! Thanks Kevin!

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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:** [August 13, 2020, 4:31pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-device-issue/37667/5 "2020-08-13T16:31:38Z")

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In a recent version we cleaned up the error diagnostics on tags that have an incorrect OPC server name:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/4/5/45deaecadb584009ab9f23bf236682d17ebdb79b.png)

and

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/5/1566073de5d779452c976a19d2baf21c611de95b.jpeg)  
Hopefully this helps people out in the future.