Issue with ENTTEC USB DMX PRO Mk2 on Debian 10

[lightsbybrian]

Hi,

I have a system that was formerly running Debian 8, a somewhat-aging build of my fork of QLC (which adds a followspot feature), and an ENTTEC USB DMX PRO Mk2. This setup has been working very dependably.

However, I have recently updated my system to Debian 10.7, and neither my private fork nor the latest binary from qlcplus.org will operate the ENTTEC adapter properly. Here's a screen shot of the official QLC latest release, and part of the obvious bad behavior:

Notice that the name/serial field of the controller shown in QLC is garbage characters. Also, the Mk2's status light is just flashing white (no green or yellow to indicate DMX output activity).

If I go to the settings for the output, I see that it has selected "Pro RX/TX" protocol. I can manually set this to "Pro Mk2" but it has no positive effect.

The garbage characters make me think that the underlying serial protocol is perhaps set to the wrong baud rate, but I have no easy way of testing that theory.

My libftdi-dev installed version is 0.20-4. What other version information should I check?

So far my "workaround" is just to run the old Debian 8 system, but I'd really like to get the Deb10 system into a fully functional state. Plus there are some additional features I want to add to my fork, and ideally I'd do that on my newer system...

Thanks in advance for any tips/help!

Cheers,
-Brian

PS: I'm working on whipping up a simple test program outside of QLC+ to see if I can talk to the thing at all on this system. Then I can maybe determine if it is an issue outside QLC+. (It's hard to confidently blame QLC+ when it was working on another system...)

[lightsbybrian]

Go figure, it was a udev rule / permissions problem.

It's a strange sort of manifestation of a permissions issue to have the device name show up as garbage characters, instead of simply not enumerating at all. At any rate, I discovered the problem after determining that my standalone test program had to be run as root to work, and then I tried running QLC+ as root, and everything worked then. So I checked my udev rules files, and realized the one that should be setting the correct permissions was not named properly. Fixing that fixed the issue. In particular, I had to rename '/etc/udev/rules.d/z65-dmxusb.rules.dpkg-new' to '/etc/udev/rules.d/z65-dmxusb.rules'