Hello! Our customer uses X20CP3684, with software version: Version V 4.12.2.93 (2022-05-25) and runtime version: 4.93.0 communicate with 3 devices using IEC-104 protocal . The current issue found is that individual stations frequently experience communication interruptions with 104 protocol. Our E…

Hi, Unfortunately I don’t have source code available, I’m sorry. From what I know, the SO_KEEPALIVE is only needed if there’s no data flow on the TCP channel for a very long time but the channel should kept open - then, keepalive packets are sent automatically from the TCP stack after the configur…

Dear Shenyang, is this an APROL project? If not, please check the status of the TCP function blocks. Does the status display an error code? Best regards, Stephan

Hello Stephan, No it’s not an APROL project. I am asking the customer for the status and will get back if there is an update. Thanks!

Just to make sure… We do not - at least to my knowledge - offer a IEC 104 library outside of APROL. So the customer has implemented the protocol on it’s own?

Hi, I don’t know the IEC-104 protocol or the implementation behind (it’s not a B&R lib delivered together with Automation Studio, right?). Therefore it’s hard to say, but I think it has to be debugged on application level. The FIN is nothing IEC-104 specific, it’s part of the 3-way handshake of t…

Yes they have implemented it by there own. So actually it’s a TCP issue.

Thanks Alexander, I also think this is an TCP issue. Do you have some example code about how to deal with the timeout and port release of TCP? Or how to use the SO_KEEPALIVE function if it is also help? Then I can give the customer to have a reference.

Hi @shenyang.zhou what is status of your topic, can you update us with your findings?

IEC 104 communication disconnection

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shenyang.zhou (Shenyang Zhou) February 2, 2026, 7:52am 10

Hello,

I just recommend Alex’s suggestion to the customer, and I have not receive any feedback from them.

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IEC 104 communication disconnection

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