flickering and loss of control

[thundermonkey]

Hi, I am moving a community ballet theater from an ETC light board to a laptop-controlled setup. So far I am enjoying using QLC+, and the move looks like it will be successful. Thank you to the devs for their hard work on this useful program.

I would appreciate advice on two intermittent issues, flickering and loss of fixture control. Our setup is a Lenovo IdeaPad 3 laptop running Windows 11 and QLC+ version 4.12.6, and the interface is an Enttec Open DMX USB. We have 40 fixtures.

Flickering: sometimes when I start a new session I notice a flickering - a short drop of intensity - of all the fixtures, at the rate of a few times a minute. It seems like I can induce this flickering through the use of the mouse.

I have seen other posters mention this problem, and I tried a few suggested things: a switch to wired mouse, turning off other programs including antivirus, eliminating physical vibration of cable, etc. However these didn't prevent the flickering from showing up again. What I found worked to end it - if it showed up - is a laptop reboot.

Loss of fixture control: yesterday after starting up I noticed an American DJ Starburst fixture wasn't responding well - scene changes would alter its state, but incorrectly. I couldn't shut it down by sending zeros to all of its channels. (Other fixtures might have been misbehaving, this one was the most obvious.) Alarmingly, a laptop reboot did not help. What did restore control was disconnecting the USB cable to the Enttec interface and plugging it back in while the laptop was on.

Is there a particular order to starting up a session (cable connection, rebooting) which prevents issues in general? Has anyone else experienced these particular issues on a Windows laptop? If so, have the remedies (rebooting, cable disconnection) ever failed to help?

thanks in advance, Travis

[GGGss]

Welcome to the forum,

Flickering or your described behaviour points back to a disturbed DMX signal train.
With the open DMX interface, it is the processor of your laptop which is in charge of the DMX timing. Wiggling your mouse eats some resources, hence the processor doesn't have spare resources to build the DMX signal train continuously.
Rebooting resets the threads needed for that, unplugging the USB resets the threads also...

The solution is to reduce the DMX timing. The default DMX refresh frequency QLC+ uses is 44Hz. I'd suggest lowering this to say 30Hz. Moreover, you can limit the number of channels which are sent. This might work for you.

IMHO: 40 Fixtures is out of spec for 1 DMX line (31 members max), so a repeater or splitter is also needed to get back into the DMX spec. With 40 fixtures I would opt for an intelligent DMX interface. The difference will be instantly noticeable. It is now the intelligent DMX interface which is in charge to build the continuous DMX signal train and the processor of your laptop only has to instruct what changes have to be sent. Makes a huge difference in your lappie's processor load...

[thundermonkey]

Thanks for the quick reply. I will upgrade to an Enttec PRO since it seems the hardware is on the edge with my current setup. However I will also play with the timing and channel parameters, to see if I can get the Open more reliable so we can use it as a backup.

Two follow-up questions:

You mention a default 44Hz refresh frequency, but the parameter tuning page in the documentation indicates a default 50Hz for a master timer frequency, are these different frequencies?

If I try to change the number of Open channels transmitted via the Windows registry, is there any way of knowing if I've succeeded? Or of determining if I've changed the refresh frequency?

[GGGss]

You mention a default 44Hz refresh frequency, but the parameter tuning page in the documentation indicates a default 50Hz for a master timer frequency, are these different frequencies?

You have the DMX bus refresh frequency (FPS Frames per second). 44Hz default for QLC+ (30Hz for GrandMa, 37Hz for city theatrical ...)
Then the engine has a cycle time also. This can be set in the registry is for some reason this needs to be altered. 20ms of 50Hz QLC+ default.

If I try to change the number of Open channels transmitted via the Windows registry, is there any way of knowing if I've succeeded? Or of determining if I've changed the refresh frequency?

This has to be measured for verification. I always carry a DMX tester/measurer... but again, I'm mostly called in when things go wrong... therefore
DMX cat is my favorite tool for that. €340-ish

Once your Enttec pro will arrive, you'll notice an instant improvement. Unluckily the MK2 isn't deliverable anymore; you get 2 universes for approx the same price.
Make note though that to make your rig DMX spec compliant, you also need a splitter / repeater. (31 device max on 1 cable)