# Modbus RTU Connection

**URL:** <https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447>\
**Category:** Ignition\
**Created:** [June 13, 2018, 3:00pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447 "2018-06-13T15:00:53Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![harryzhou4498](https://avatars.discourse-cdn.com/v4/letter/h/71c47a/32.png) [@harryzhou4498](https://forum.inductiveautomation.com/u/harryzhou4498)\
**Post date:** [June 13, 2018, 3:00pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447/1 "2018-06-13T15:00:53Z")

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I have an older Modbus RTU device that I’m trying to connect to via Ignition, but I don’t think it has an IP address for the Modbus RTU over TCP driver. How can I establish a connection with it using that driver?

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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:** [June 13, 2018, 3:04pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447/2 "2018-06-13T15:04:28Z")

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That driver assumes you’ve placed a dumb serial-to-ethernet converter in front of it.

If you don’t already have hardware, buy a proper Modbus gateway to sit in front and then connect the regular Modbus TCP driver to it.

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<div class="post-metadata">

**Author:** ![harryzhou4498](https://avatars.discourse-cdn.com/v4/letter/h/71c47a/32.png) [@harryzhou4498](https://forum.inductiveautomation.com/u/harryzhou4498)\
**Post date:** [June 13, 2018, 3:11pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447/3 "2018-06-13T15:11:38Z")

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Are there any other viable alternatives aside from buying a modbus gateway?

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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:** [June 13, 2018, 3:16pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447/4 "2018-06-13T15:16:43Z")

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Plug it straight into your gateway a on serial port, and buy the Gateway Serial Support module. Then the modbus driver can use the serial port.

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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:** [June 13, 2018, 3:16pm UTC](https://forum.inductiveautomation.com/t/modbus-rtu-connection/18447/5 "2018-06-13T15:16:52Z")

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If you buy the Gateway Serial Support module and install it a Modbus RTU driver will appear. If you’ve got a serial connection from the gateway machine to the device you can use that.