# Modbus tcp of Siemens s7-12000
**URL:** https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710
**Category:** Industrial
**Tags:** modbus
**Created:** [3 April 2022 09:37 UTC](https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710 "2022-04-03T09:37:51Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Nam](https://discourse.nodered.org/u/Nam)
#### Post date: [3 April 2022 09:37 UTC](https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710/1 "2022-04-03T09:37:51Z")
Can anyone help me with some examples to communicate modbus tcp between two PLCs? Thank you very much
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### Author:  [@MountainKing91](https://discourse.nodered.org/u/MountainKing91)
#### Post date: [3 April 2022 20:01 UTC](https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710/2 "2022-04-03T20:01:28Z")
Hi,
take a look a [node-red-contrib-modbus](https://flows.nodered.org/node/node-red-contrib-modbus) by Klaus Landorf aka biancode.
Basically you need to know from your plc:
- ip address
- modbus port (usually 502, but I imagine you can set it up in TIA Portal when you configure the Modbus TCP function block)
- registers address you want to read/write
You don't provide any context for your situation, but I guess Node-RED would be the client polling registers from your PLCs (which are servers). Each plc has its own IP address and than it's pretty much the same setup for all the plcs (Siemens official documentation is all you need). In this scenario a plc doesn't communicate with the other.
Be careful about what you're doing, especially with production machines..
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### Author:  [@Nam](https://discourse.nodered.org/u/Nam)
#### Post date: [6 April 2022 06:02 UTC](https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710/3 "2022-04-06T06:02:08Z")
Thanks so much ! i will try it
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [5 June 2022 06:02 UTC](https://discourse.nodered.org/t/modbus-tcp-of-siemens-s7-12000/60710/4 "2022-06-05T06:02:12Z")
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