Serial sensor integration

Configuration
1

Hi,
Maybe some of you have had a similar problem with the serial port…

  • HA (2025.10) as a VM in Proxmox;
  • Prolific pl2303 converter connected to the USB port;
  • USB passthrough as device ID;
  • recognized in HA
# dmesg -T |grep tty
...
[Wed Oct  8 23:00:19 2025] usb 2-1: pl2303 converter now attached to ttyUSB0
...

Cable/converter for 100% works fine - when I do
# cat /dev/ttyUSB0
I see the correct messages on the terminal/console send by RS232 device
Configured serial in HA as:

  - platform: serial
    baudrate: 2400
    serial_port: /dev/ttyUSB0

BUT the entity sensor.serial_sensor itself has state: unknown…

This configuration worked for more then years - what has changed:

  • about month ago I had to replace RS232 end device but new one has the same RS232 parameters, configurations etc
  • updated HA from 2025.09.xx

Any idea?

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