I have installed Ubuntu Core 16.04 (GNU/Linux 4.4.0-135-generic x86_64) in a industrial PC Dell. I'm running Node-Red and now I need to connect serial ports to be read on the PC.

When run node-red displays this error:

2018-11-02T11:49:19Z node-red.node-red[4692]: 2 Nov 11:49:19 - 
[error] serial port /dev/ttyACM0 error: Error:
Error: Permission denied, cannot open /dev/ttyACM0

I'd try to set ttyACM0 in a group (called QR) saved in /home/admin, typing this:

root@4LVL902:/home/admin# ln -s -T /dev/ttyACM0 QR
root@4LVL902:/home/admin# ls
QR  images  node-red_0.19.4_amd64.snap  snap

But the problem is the same:

2018-11-02T11:41:32Z node-red.node-red[4692]: 2 Nov 11:41:32 - 
[error] serial port /home/admin/QR error: Error:
Error: Permission denied, cannot open /home/admin/QR`

I know it's a permission problem, but I'm new to Ubuntu and don't know how to solve it. What folders or files have node-red permission? Do I have to put the QR group under node-red folder? node-red is installed in home/admin.

Also one of the devices has to install drivers (RS232) to work, but don't know how to do this on Ubuntu Core.

  • 3
    Possible duplicate of How to find serial port – N0rbert Nov 2 '18 at 11:37
  • I've modified the question, now I have my serial port located but it's a permissions problem between node-red and the serial. Also, command "setserial" doesn't work in Ubuntu Core (or doesn't work for me...). – BelenFz Nov 2 '18 at 12:04
  • 1
    Then you need to add your user to dialout group with sudo usermod -a -G dialout $USER. – N0rbert Nov 2 '18 at 13:54

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