DMX addressing
Three numbers. Two are entered on the fixture — the start address and the footprint of the chosen mode — and the third, the universe, comes from the cable.
Address, footprint, universe
A fixture listens from an address, over a number of channels set by its mode: that is its footprint. A moving head in 20-channel mode addressed at 1 takes channels 1 to 20; the next one therefore starts at 21, not at 2. A DMX universe carries 512 channels, which is twenty-five of those fixtures and not one more.
The universe comes from the cable, not from a field to fill in
The universe is entered only at the source — a console output, an Art-Net node output, a splitter output that changes universe. Everything chained behind inherits it, because that is what a DMX cable does: it carries the universe of the port it leaves. Typing it on every fixture would make it a value kept by hand — so a value that is wrong the first time the cabling changes.
What breaks, and does not show
Four faults slip into a lighting patch unseen: two fixtures whose ranges overlap (the second sits on the first one’s channels, and nobody works out why fixture 4 moves when you push 3); a range that runs past 512; a fixture the cabling ties to two universes at once; and a half-entered patch, an address with no footprint, which means nothing at all.
One conflict, as the engine sees it
Here are two fixtures addressed by hand on the same universe, and what the engine says about them. The verdict was not written for this page: it comes out of the same function as the app’s Checks tab, run on the small rig below.
- Moving head 1 — address 1, footprint 20 channels
- Moving head 2 — address 10, footprint 20 channels
Refused Moving head 1 — Moving head 1 overlaps Moving head 2 in universe 1: channels 10-20 are addressed twice. Two devices on the same channels answer the same command together: move one address past the other’s range, or split them across two universes.
Refused Moving head 2 — Moving head 2 overlaps Moving head 1 in universe 1: channels 10-20 are addressed twice. Two devices on the same channels answer the same command together: move one address past the other’s range, or split them across two universes.
The ×N block, and the chain
Eighteen identical fixtures are drawn as one block carrying its quantity: the addressing follows, instance after instance, and the chaining jumpers count themselves into the cable list. Eighteen blocks drawn by hand would give the same plot and eighteen times more to correct when the mode changes.
The canvas is already open
Drop five devices, pull cables between their ports: the cable list, the patch sheet and the equipment list fill themselves in while you draw. No account, no card.