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UDP with Node-Red

chr$chr$
in PLCnext Technology & PLCnext Controls

Hello, I have a problem with the implementation of UDP connectivity with Node-Red. I used port 8888 and can send data from my EPC 1502 but can not receive data. The firewall on the EPC 1502 is not activated. Is there any other parameters to tune to enable my EPC 1502 to receive data on UDP ?

Comments

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]
    edited November 2023

    To help diagnose the source of the issue, have your tried receiving UDP data on the same port from a shell session on the EPC, using netcat ? Something like:

    nc -u localhost 8888

    EDIT:

    I just realised that this probably won't work with the version of netcat that is currently included in the firmware ...

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]

    As an alternative to Node Red, you could try a simple PLCnext Engineer project containing the UDP_SOCKET_2 and UDP_RECEIVE_2 function blocks, and see if UDP data is received that way. Hopefully that will help to diagnose the problem.

  • Stefan BrinkmannStefan Brinkmann

    Hello,

    I think the problem is that Node-RED is running in a container. Sending data via a port from the container works. But sending data to the container only works, if a port mapping is done between the container and the host. This is usually done, when the container is started. I am not sure how to achieve this in an already running container.

  • chr$chr$

    Hello, thanks for your support. I didn't change anything but now it works. Strange...

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