Modbus integration 2 PIs. HA on one, pymodbus on other?

Am new, so apologies on forehand for a possible stupid question :slight_smile:
Spent week on getting HA up and running on a rpi4 with everything in my house. Managed to do 95% with the help of google and existing community forum feedback or existing posts.
Due to reason decided to go to HA-OS. Problem with that is restricted access. (Tried some things to get around, like add-ons, but till no success). 2 problems remained:

  • could not get serial port to work in rpi4 in HA-OS
  • could not get a rtsp server installed on HA-OS.

So decided for a second rpi (a rpi3). The second rpi has now the rtsp server serial is working.
What i can’t get working is running a pymodbus serialclient on the rpi3. I want to point the HA modbus integration on the rpi4 (tcp, rpi3 IP address, port 502)) towards rpi3 serial.
Can find very little (good) examples of a decent pymodbus serialclient to get the job done.
Asking help for:

  1. is pymodbus the best way to go in this case (rpi3 serial connection to SDM630)
  2. any example for pymodbus serial for this use case anyone can share?

Thanks in advance for helping this noob
(Installed: Hue, Tuya, Eastron sdm630, rtsp server (reolink camera’s) viewable via iframe in HA, heatpump (Heliotherm), shelly, media, P1 essent meter, PV installation goodwe)

TL; DR version-

Anyone have a good pymodbus serial client rtu example that reads serial (/dev/serial0) on PI1 which is connected to HA on PI2 (using Modbus TCP)?
Or is there a better way to integrate modbus reading on PI1 while HA is on PI2?
Thanks in advance

Is this such an odd topic or strange question?
Took me a lot of work to find a solution but eventually did and it is working now.