# MODBUS TCP driver

**URL:** <https://forum.inductiveautomation.com/t/modbus-tcp-driver/11705>\
**Category:** Ignition\
**Created:** [May 20, 2016, 8:30pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver/11705 "2016-05-20T20:30:25Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Wael](https://avatars.discourse-cdn.com/v4/letter/w/b9e5f3/32.png) [@Wael](https://forum.inductiveautomation.com/u/Wael)\
**Post date:** [May 20, 2016, 8:30pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver/11705/1 "2016-05-20T20:30:25Z")

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Hi, I would like to know how to access output coils in an M340 processor.  
the PLC is configured tn topological addressing (and not state) format (i.e Qx.x.x) and I wonder how to translate this format from ignition side.  
thanks

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**Author:** ![anna](https://avatars.discourse-cdn.com/v4/letter/a/779978/32.png) [@anna](https://forum.inductiveautomation.com/u/anna)\
**Post date:** [June 15, 2016, 11:47pm UTC](https://forum.inductiveautomation.com/t/modbus-tcp-driver/11705/2 "2016-06-15T23:47:29Z")

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Wael,

You need to figure out what Modbus addresses you need to be looking at.  
For coils, your address will be something like `[connectionName]C1000` where 1000 is the address of the bit you are looking at inside the Coils area.

You can see more information on how to address Modbus tags in Ignition here: [https://docs.inductiveautomation.com/display/DOC/About+Modbus+Addressing](https://docs.inductiveautomation.com/display/DOC/About+Modbus+Addressing)