Systemd service does not work as described

[winfriedp]

• ModBus TCP proxy version: 0.6.8
• Python version: 3.9
• Operating System: Raspberry Pi OS Bullseye v11.5

Description

The service configuration does not work when installing modbus-proxy according to the instructions. I get an ModuleNotFoundError: No module named 'modbus_proxy'. The reason is that modbus-proxy is installed in a local user directory, but the service is run by the user root and root does not know the local directory. I am not a python expert and I have not found a solution to adjust the environment variables so that root can handle them.

What I Did

I solved the problem by installing modbus-proxy as user root as follows: sudo su pip3 install modbus-proxy

Then the package will be installed in /usr/local/bin/ and /usr/local/lib/python3.9/dist-packages Now the service can be started without error. This workaround is OK for me, but maybe there are other suggestions from python experts to make this service work.

[requiemmg]

I cannot start the service. First I did as stated in the documentation, status failed. Then I saw your report and uninstalled modbus-proxy as a user and reinstalled as root. I also tried to use absolute paths, but no success. When I run from bash, everything is fine.

● mproxy.service loaded failed failed Modbus-Proxy

My mproxy.service (in etc/system/systemd) looks like this:

[Unit]
Description=Modbus-Proxy
After=network.target

[Service]
Type=simple
Restart=always
ExecStart = /usr/local/bin/modbus-proxy -c /usr/lib/mproxy-conf.yaml

[Install]
WantedBy=multi-user.target

Any ideas?

[winfriedp]

The only difference to my service definition is the ExecStart command. Try ExecStart = modbus-proxy -c ./usr/lib/mproxy-conf.yaml I guess it's only the missing dot before the slash.

[requiemmg]

Did so, still failing and I dont know why as it runs smoothly from the command line.

[tiagocoutinho]

Could you send the systemctl log:

journalctl -u mproxy > /tmp/mproxy-log.txt

[requiemmg]

Sure, no problem. I have it working now with a modbus-proxy fork for Home Assistant.

mproxy.log.txt

[tiagocoutinho]

looks like you installed modbus-proxy on root without yaml support. Maybe you did something like: sudo pip install modbus-proxy

You need to do instead: sudo pip install modbus-proxy[yaml]

[requiemmg]

Thanks for the clarification!

[thaichho]

I had also issues but with the help of this thread I was able to solve them. Anyway it might be better do enhance the README File

[Richigeht]

@tiagocoutinho why don't you do that with a PR on this repo and more information? :-)