No connection to Lightburn after upgrading to Ubuntu 22.04

I have been using Lightburn 1.1 under Ubuntu 21.10 with no troubles on an Asus Core I7 laptop.
I then upgraded Ubuntu to 22.04 and found that Lightburn could not connect to my Sculpfun S9 laser.
I performed an lsusb command and found the"1a86:7523 QinHeng Electronics CH340 serial converter(found in my Sculpfun) was recognised by Ubuntu. I then performed a dmesg command and found that the CHG340 serial converter had been linked to my Webcam, making it unavailable to Lightburn.

Then I issued the command grep -riIn “1a86:7523” /usr/lib/udev/rules.d/*
and this returned the result
/usr/lib/udev/rules.d/85-brltty.rules:330:# Device: 1A86:7523

Ah, that was what was wrong. My 1A86:7523 CHG340 had been claimed as a Braille device.
I commented out the offending line,
ENV{PRODUCT}==“1a86/7523/*”, ENV{BRLTTY_BRAILLE_DRIVER}=“bm”, GOTO=“brltty_usb_run”

But I still wasn’t out of the woods. I still could not access the laser.
Next I added the following line to /usr/lib/udev/rules.d/70-uaccess.rules
SUBSYSTEM==“tty”, ATTRS{idVendor}==“1a86”, ATTRS{idProduct}==“7523”, GROUP=“users”, MODE=“0666”
3D printers, CNC machines, laser cutters, 3D scanners, etc.

I restarted the machine and success. Lightburn can access my Sculpfun S9 from Ubuntu 22.04

I hope this information can be useful to any other Ubuntu user who cannot access his laser after upgrading Ubuntu.


Probably needed to reload udev rules…

Should stop communications, reload ‘rules’ and the triggers and restart communications… I usually get away with just

udevadm control --reload-rules
udevadm trigger

It should avoid a re-boot.


Good point

Anytime you modify the source data to a system ‘part’ you need to ‘roll it over’ so it restarts and re-reads the data. You have to play the same game with DHCP and other system ‘things’…

Funny, when I first went to work in computers, I fixed terminals. It was rather surprising to go to someone cubical at night and find they have a braille terminal…

Couldn’t fix it without their help… :crazy_face:

Take care


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