USB Passthrough (for Modbus) from Pi 5 to a Docker container

General
,
1

I would like to pass though an USB FTDI RS485 to Node-RED on a RPi 5.

This is my compose file:

services:
  node-red_dev:
    image: nodered/node-red:4.0.2
    container_name: node-red_dev
    restart: unless-stopped
    privileged: true
    user: node-red
    group_add:
      - dialout
    ports:
      - 1880:1880
    networks:
      - net
    volumes:
      - dev_data:/data
    devices:
      - /dev/ttyUSB0:/dev/ttyUSB0

networks:
  net:

volumes:
  dev_data:

This is the output from the console:

~$ whoami
node-red
~$ id
uid=1000(node-red) gid=1000(node-red) groups=20(dialout),1000(node-red)
~$ ls -l /dev/ttyUSB0
crw-rw----    1 root     dialout   188,   0 Jul 16 12:57 /dev/ttyUSB0
~$ dmesg | grep ttyUSB
[   30.610798] usb 3-1: FTDI USB Serial Device converter now attached to ttyUSB0

I can see the FTDI device in the console but I can't get the node-red-contrib-modbus node to work in Node-RED.

Not sure if there is a dialout group mismatch.

I am out of my depth and any assistance would be appreciated. TIA.

3

When you say console, you mean on the host or a shell inside the container?

4

The above is from inside the container. Below is from the host.

~$ whoami
pi
~$ ls -l /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 0 Jul 17 18:17 /dev/ttyUSB0
~$ id
uid=1000(pi) gid=1000(pi) groups=1000(pi),4(adm),20(dialout),24(cdrom),27(sudo),29(audio),44(video),46(plugdev),60(games),100(users),102(input),105(render),106(netdev),993(gpio),994(i2c),995(spi)
5

So by using image tag 4.0.0-debian it works. Assume it something to do with Alpine base?

6

What host OS are you running on? 32 or 64bit?

7

Raspberry Pi OS Lite 64bit