Access RS232/serial port that is already in use (remote device)

1

Hi all!
I’ve now tried it for several days but no success, therefore I am asking for your assistance.

I have got a central heating controller that manages my radiators and boiler. This controller does not have any Ethernet capabilities because it is quite old, but it has RS232 serial port which I am already accessing with a small tool from the manufacturer. That tool is installed on a Windows laptop which is located near the controller and running 24/7. For the connection wiring I am using a USB-to-serial-converter which is working fine. Via RDP or TeamViewer I can access this machine, change some values/temperatures and see statistics. So the RS232 port is already in use with the original software. The RS232 protocol definition is available from the manufacturer.

Now I’m trying to add the controller also in to HA while keeping the original software in place. I have 2 ideas but appreciate any other suggestions:

    1. Parsing the logfiles of that software as it’s logging the values to .dat files, unfortunately these are totally unreadable bytestreams and no TXT/CSV. The manufacturer does not provide any help in parsing/decoding/decompressing the data. I fear parsing the files it not possible without knowing anything about the data structure. Also asked ChatGPT to identify the values inside the data but no luck.
    1. Trying to add the RS232 into my HA and sniff those packages that are sent/received anyways while the original software is running. I’ve tried this with a software relay on the Windows machine but did not succeed. Current idea would be to add a Serial-to-LAN-Box and let the original software running with this. I hope I’d be able to sniff the Serial-to-LAN-Converter with HA to get the same values as the software tool is getting. HA would not have to request/send any data to the serial connection, cause the “traffic” is being done by the main connection controller<>software. HA would be read-only.

Does anyone know if or how this is gonna work?
My HA is running on a VM (HAOS) while the original software tool is Windows-only.

Hopefully my request is understandable, please let me know any questions.
Thank you!