This is actually a common requirement so it’s definitely something I’ll be thinking about in future, and ultimately adding ArtNet DMX control to Liberation.
But in the meantime there is a workaround using MIDI Send/Receive. It’s a different system to the APC40 connection, and there’s more about it in the user guide :
And you can see how it’s mapped here :
Global brightness is control change 15 on channel 16. There is also a workaround to give HSB colour control to a lighting desk using custom effects.
See RGB control via a Lighting console for more information about how to do this.
As for the connection between the console and the PC…
Wired MIDI connector
I’m not particularly a lighting console expert but I know that some of them have a MIDI output, or can with an external MIDI interface. If you also have a MIDI interface on your PC, you can literally just use a standard 5 pin MIDI to connect the two. (PC MIDI interfaces are cheap, and some sound interfaces also have one built in)
Network MIDI
Additionally, some lighting consoles also support network MIDI (known as RTP-MIDI), so you can transmit and receive MIDI if the console and your computer are on the same network.
I’ve had a lot of success with this method in the past, but it can be very confusing to set up. It’s built in to MacOS but on Windows you need to use another app.
Hope this helps!
Seb