# Modbus TCP Connection issue

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-connection-issue/34394>\
**Category:** Ignition\
**Created:** [May 4, 2020, 5:15am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-issue/34394 "2020-05-04T05:15:50Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rs326](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/rs326/32/4500_2.png) [@rs326](https://forum.inductiveautomation.com/u/rs326)\
**Post date:** [May 4, 2020, 5:15am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-issue/34394/1 "2020-05-04T05:15:50Z")

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![Fatek Issues](https://us1.discourse-cdn.com/inductiveautomation/original/2X/5/5d6e9e881903b3d689d97aa84e2eb675e3797d90.png)

I am having issues connecting to a fatek PLC over a modem.

I am able to connect to it when I test with my laptop on the machine.

But not over the network. I would appreciate guidance on where I should be looking at.  
I am able to connect to other modbus and Siemens devices on the same switch but only this particular device is giving me trouble.

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**Author:** ![SBL\_MC](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/sbl_mc/32/56813_2.png) [@SBL\_MC](https://forum.inductiveautomation.com/u/SBL_MC)\
**Post date:** [May 4, 2020, 1:38pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-issue/34394/2 "2020-05-04T13:38:11Z")

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Does your laptop use modbus tcp as well?

Please share more about your setup.

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<div class="post-metadata">

**Author:** ![rs326](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/rs326/32/4500_2.png) [@rs326](https://forum.inductiveautomation.com/u/rs326)\
**Post date:** [May 7, 2020, 9:03am UTC](https://forum.inductiveautomation.com/t/modbus-tcp-connection-issue/34394/3 "2020-05-07T09:03:57Z")

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HI SBL,

I think I found the issue, There was Layer 3 network connection between the PLC and my computer.  
I was able to ping the PLC but could not get modbus tcp connection to it.

Interestingly enough I had a Siemens(connected through Ignition Siemens driver) and an Ezlogix PLC connected through modbus working through the same layer 3 network connection. It was only the Fatek PLC causing the issues.  
I changed the connection to layer 2 and it worked.