# Not connected Device Modbus

**URL:** <https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [March 14, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026 "2023-03-14T13:59:00Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![gerardopignatiello96](https://avatars.discourse-cdn.com/v4/letter/g/df788c/32.png) [@gerardopignatiello96](https://forum.inductiveautomation.com/u/gerardopignatiello96)\
**Post date:** [March 14, 2023, 1:59pm UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026/1 "2023-03-14T13:59:00Z")

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Hi,

I have two machines (Machine-1) one with ip address 192.168.178.97 where ignition Maker is installed and the other runs the Modbus Poll software which shares values with ip 192.168.178.21 (Machine-2)

I'm trying to make a modbus connection between the two, but it won't connect.

I did the following setup:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/a/9/a95c9f71553d1857fc57bb6d25cfd3bb91bdcc04.png)

but nothing, while if I enter localhost it works correctly, What could be the problem ?  
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:** [March 14, 2023, 4:06pm UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026/2 "2023-03-14T16:06:50Z")

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Is the Modbus Poll software a master or a slave? What's the error in the logs? Why does localhost work, do you have slave software running there?

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**Author:** ![gerardopignatiello96](https://avatars.discourse-cdn.com/v4/letter/g/df788c/32.png) [@gerardopignatiello96](https://forum.inductiveautomation.com/u/gerardopignatiello96)\
**Post date:** [March 15, 2023, 8:32am UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026/3 "2023-03-15T08:32:01Z")

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Thank you for answering  
Modbus salve.  
locally it works correctly, yes, I ran a test with Modbus slave running on the machine locally::

 ![localhost](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/8/e85dbe9bb87826cfb946de589cc8f22f444bf3af.png)  
 ![localhost_read](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/0/205a545f9abad982ae7e92049f37df48dc14817f.png)

If I run the test with two different machines having same subnet (Ignition 192.168.178.97 and Modbus slave 192.168.178.21 ) it doesn't work, Ignition won't connect.

 ![not_localhost](https://us1.discourse-cdn.com/inductiveautomation/original/3X/0/2/02f4558322a27bc142be84eb100029157991b409.png)

there aren't log

 ![not_log](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/e/2ea0798af444ffb572532745f7b17f9fb9104e0d.png)

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<div class="post-metadata">

**Author:** ![jonathan.taylor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jonathan.taylor/32/4048_2.png) [@jonathan.taylor](https://forum.inductiveautomation.com/u/jonathan.taylor)\
**Post date:** [March 15, 2023, 8:39am UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026/4 "2023-03-15T08:39:20Z")

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Does the second machine have a firewall thats blocking port 502?

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<div class="post-metadata">

**Author:** ![gerardopignatiello96](https://avatars.discourse-cdn.com/v4/letter/g/df788c/32.png) [@gerardopignatiello96](https://forum.inductiveautomation.com/u/gerardopignatiello96)\
**Post date:** [March 15, 2023, 1:27pm UTC](https://forum.inductiveautomation.com/t/not-connected-device-modbus/71026/5 "2023-03-15T13:27:46Z")

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yes, the port 502 was locked.  
I have now opened the port 502 and everything works fine.  
Thank you