How to read a response from USB/RS485 dongle - is HA scrap for nothing?

And you get nothing in the logs when you send the command? I would say that is odd. You are testing by sending the command correct? I would use Dev Tools/Services:

I assume you restarted the system after the second change to the logging too.

It is likely you might have a permissions issue. When you are monitoring the send and receive you are ikely NOT the user “homeassistant” and you are the user “homeassistant” when you are executing the command inside home assisnat. You have to make sure the “homeassistant” user is in a group that can read/write to that port.

yes, restarted after each modification. Yes log is done after click on the button for command sending.

send command is relly working correct, I can see that command was sent

Regarding permissions. Not sure what you mean and how to check. For HA I’m a administrator.
I’m using this home assistant version :
ODROID - Home Assistant (home-assistant.io)

Is this for some audio component system or ?

This communication I need for control of main unit for individual room temperature control

OK. You may wish to ask the person here, they had other issues but got so far and had the same problem. As I stated at the end, it could be permissions in reading from the port. I would ask them if they solved their issue:

I have a Dayton Audio Dax88 multizone amplifier but I also use core on a Linux OS (Linux Mint) and had to add some permissions to homeassistant user but it all runs flawlessly. But that is all built int python code and not just a general serial entity.

So complete Home Assistant is useless when he isn’t able do a basic functions read/write ports ?

For me looks like no chance to get working = throw away home assistant

I can … I have two networked Dax88 Amplifiers with RS232 to USB which is 15 Audio zones and 7 inputs each plus Wfi, all in Home Assistant. Can turn music on/off in any zone, change inouts, adjust volumes … I have no issues with that entire part of my system.

ok, can we modifiy for my system ?
Any chance to check / modify permissions for usb port ? Use python? use node red ?

I do not know anything about your implementation, mine is raw Linux. But certainly on raw Linux the homeassistant user (the user the system runs as) must be a member of dialout group

ok, your rs232 communication is running via python script implemented in HA?

Python code, but little difference between it and standard serial code posted for you above which is Home Assistant. The difference is building a specific solution or using a generic one.

I know nothing about ODROID mostly because I had several server class machines lying around and could just take one and install Linux Mint and Home Assistant Core, which gives me Linux and many other things I put on same machine … Kodi, VLC, much more. I dot think I would ever go to a canned small box installation.

looks like I have no chance to get working

Python Scripts - Home Assistant (home-assistant.io)

implement it doesn’t look so complicated. Create folder, copy py file and call with parameters…
Are you able help me with it ?

Can you send me a python for sending data to a port and receiving answer?

You have Python code for getting the answer, it is posted above. It is the serial code. Granted as I said it has limited logger statements for debugging, but it is right there. You could edit the code, add additional debugging code, swap the code into your install and restart and get more log messages.

in case your missed it:

But I suspect you think things work differently than you expect. You cannot have other devices grabbing the transmission port and expect it to be released. Your saying things like other “dongles” and connections and running stuff and that is all band aids that could be causing additional problems you do not realize.

Start fresh, other the devices you expect attached. Debug. I see no messages about creating the connection or anything other than “hey I found /etc/usb0” … no sends, no receives no nothing. Hard to believe unless something else is not working.

No I don’t have other device using same dongle. This dongle is only for HA. Second dongle is connected to the PC. Both dongles are USB/RS485 - on the RS485 you can have connected more devices:

I copied complete code and started from debug :

I tried make a simple python script for serial port definition :

import serial
ser = serial.Serial(port='/dev/ttyACM0', baudrate=9600, bytesize=8, parity='N', stopbits=1)
if ser.is_open:
    logger.info("port open success")
else:
    logger.info("port open failed")

but there is a error :
2022-09-04 12:11:36.532 ERROR (SyncWorker_1) [homeassistant.components.python_script.hello_world.py] Error executing script: import not found

I also tried to start node red and get a error 502 Bad gateway!!!