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How to send and receive text strings over TCP client interface?

Mr Daniel

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Hi. I'm an experienced PLC programmer but I'm new to the unitronics universe.

I'm wondering if anybody can give me an example on how I can send and receive text strings over TCP client interface?

I'll be using a UNIStream PLC to communicate with a robot arm using a TCP connection. 

I would like to connect to the robot on port 29999 to send different commands. The robot will then come with a reply. For example:

  • Command sent to robot:
    • "load <robotprogram.file>"
  • Return value on success:
    • "Loading program: <robotprogram.file>"
  • Return value on failure:
    • "File not found: <robotprogram.file>"
    • "Error while loading program: <robotprogram.file>"


The Ladder functions "TCP Client Tx", "TCP Client Rx" and "TCP Client Connect" is not documented in the help file...

What's the correct way to use string data as buffer source or buffer destination?


I will appreciate any support!

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Hi Daniel, 

you can find example projects on many subjects that could assist you including TCP IP communication:

To download UniLogic example folder see the next link:

https://unitronicsplc.com/Download/Support/UniLogic/UniLogic Examples_V1.19 Rev 80.7z 

Please follow the next link to download an example project that will be  helpful for you (communicating with a 3rd party device via TCP). 


Please see the the next tutorial on how to use "Message Composer":


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