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Fixtures and modes
What a fixture's channel layout is, what a DMX mode changes, and where modes come from in Relackout's fixture library.
Every DMX light Relackout controls is a fixture: a device that listens to a block of consecutive channels and turns each one’s value into a specific effect. Many real fixtures also ship more than one mode — the same physical light, but with a different channel count or order depending on a setting you choose on the fixture’s own menu. This page covers what a fixture’s channel layout is, what a mode changes, why the mode you pick in Relackout has to match the one set on the device, and where modes come from in your library.
What is a fixture?
A fixture is any DMX-controlled device — a PAR, a moving head, a strobe, a fog machine — that occupies one or more consecutive channels starting at its patched address and reacts to the 0–255 value on each one: brightness, color, position, shutter speed, whatever that channel is wired to control. (How addresses and channel blocks work inside a universe is its own topic — see DMX, universes, channels and addresses.) The Demo Venue rig used throughout these guides has two good examples: a 5-channel LED PAR RGBW and an 8-channel Moving Head Spot.
A channel layout: what a fixture’s channels mean
A fixture’s channel layout is simply how many channels it uses and what each one does, in order. Two real examples from the Demo Venue rig:
| Fixture | Channels | Channel layout (in order) |
|---|---|---|
| LED PAR RGBW | 5 | Dimmer, Red, Green, Blue, White |
| Moving Head Spot | 8 | Pan, Pan fine, Tilt, Tilt fine, Dimmer, Shutter, Color, Gobo |
In Relackout’s fixture library, this layout is the model’s channel list: each channel has a name and a role (the app calls this field an attribute — more on roles below). When you patch the fixture, it claims exactly this many consecutive DMX addresses in a row.
What is a mode? Same light, different channel count
Plenty of real fixtures offer more than one mode: the exact same physical light, but DMX expects a different channel count — and sometimes a different channel order — depending on which mode is active. A Chauvet DJ Intimidator Spot 110, for example, ships with a 12-channel mode (full pan/tilt fine control plus movement macros) and a 6-channel mode (coarse control only); an American DJ Flat Par QA12 goes even further, with eight separate modes from 1 to 8 channels. Which mode is active is a setting you make on the fixture itself — an LCD menu, a row of DIP switches — not something Relackout can read off the device.
Why the mode must match the fixture’s own setting
When you patch a multi-mode fixture in Relackout, you pick a mode, and that choice decides how many channels get patched and what each one is for. If the mode you picked in Relackout doesn’t match the mode set on the physical fixture, the two sides disagree about what every channel number means — the channel Relackout thinks is Dimmer might be Gobo Wheel on the device, or the fixture might simply ignore values it doesn’t recognize. There’s no way around this from software alone: always check the fixture’s own menu first, then pick the matching mode when you patch it.
Where modes come from: the library and OFL import
Relackout’s fixture library is where modes live, and they get there one of two ways: you define them yourself (turn on Multiple mode support and type in each mode’s channel count and names), or you import them from the Open Fixture Library (OFL) — a manufacturer’s OFL file already lists its modes, and Relackout converts each one into a selectable mode automatically. Fixture library and OFL import walks through both, start to finish.
Channel roles
Every channel in Relackout’s library also carries a role (the app’s field for it is called attribute): Dimmer, Red/Green/Blue/White, Pan/Tilt, Shutter, Gobo, Strobe, and more, or Custom… for anything that isn’t on the standard list. The role changes nothing about the DMX itself — it only tells Relackout which control to show for that channel in Fixture Control: a brightness fader for Dimmer, a color picker for Red/Green/Blue, position controls (faders or a joystick) for Pan/Tilt.
A custom role can still be one Relackout recognizes: the Demo Venue’s LED PAR RGBW stores its Red, Green and Blue roles as the custom values r, g and b (you’ll see this in step 2 below), and Fixture Control still treats r, g, b as color channels and groups the three into one color picker.
Where you see it in Relackout
What’s next
Now that you know what a fixture’s channel layout and mode are, Fixture library and OFL import shows you how to build your own library, and Patching and the address map walks through patching step by step — including the Mode field when a fixture has more than one. For the universe/channel/address math underneath all of this, see DMX, universes, channels and addresses.
Updated: October 8, 2026