Learn DMX: the terms you actually need

Everything on this page is general DMX vocabulary. None of it is HitLight-specific — these terms mean the same thing on a grandMA3, in QLC+, and on a cheap controller from a market stall. Where HitLight does something particular with a term, the paragraph says so and says which part is ours.

What is DMX512?

DMX512 is a lighting control protocol that carries 512 numbered channels down a single cable, each channel holding a value from 0 to 255. It was standardised in 1986 and is maintained today as ANSI E1.11. Almost every stage light built in the last thirty years speaks it, which is why one inexpensive interface can drive a rig full of fixtures from different manufacturers.

DMX512 is one-way and unacknowledged: the desk talks, the fixtures listen, and nothing reports back. For the wiring specification and the full standards history, the Wikipedia article on DMX512 is the better reference, and we are not going to try to out-write it.

What is a DMX universe?

A DMX universe is one complete run of 512 channels — the most a single DMX line can carry. Every fixture in that universe spends from the same budget of 512: an 8-channel LED par uses eight of them, a 32-channel moving head uses thirty-two. When the 512 are gone, you do not buy a bigger cable. You add a second universe.

Most small rigs never leave universe one, and a lot of operators never need to think about this at all. What is a DMX universe? works through how many fixtures genuinely fit in 512 channels, and how to tell when you have outgrown one.

What is a DMX channel?

A DMX channel is a single numbered slot inside a universe that holds one value between 0 and 255. One channel controls one parameter: red, dimmer, pan, gobo wheel, strobe rate. A fixture never receives an instruction like "go blue" — it receives a run of consecutive channel values and interprets each one according to the chart in its own manual.

The 0–255 range is why lighting values are usually shown as percentages instead: 255 is full, 128 is roughly half, 0 is off. Channel counts are also what fill a universe, so the arithmetic matters as soon as the rig grows — see DMX universe.

What is a DMX address?

A DMX address is the channel number where a fixture starts reading. Set a light to address 1 and it claims channel 1 onward for as many channels as its mode uses; set the next one to 9 and the two never collide. The address is set on the fixture itself, on a small display or a bank of DIP switches, not in software.

Two fixtures sharing an address is legal, and sometimes deliberate — they will behave identically. Two fixtures overlapping partly is almost always a mistake, and it produces the classic symptom of one light answering another light's colour. Confirm every address on the unit rather than the patch sheet, then record it when you patch the rig.

What does patching mean in lighting?

Patching is the act of telling your software what is in the rig: which fixture model sits at which DMX address, in which mode, in which universe. The patch is the map between the physical rig and everything you do on screen. Until a fixture is patched, the software has no way of knowing that channel 12 is a tilt rather than a strobe.

Patching is where most first-night faults are actually created, and where they are cheapest to fix. Walk the rig, read each address off the fixture's own display, and check the mode while you are standing there. How patching works covers the process and what to do when a fixture is missing from the library.

What is a fixture profile?

A fixture profile is a data file that describes what each of a fixture's channels does — channel 1 is the dimmer, channels 2 to 4 are red, green and blue, channel 7 is a gobo wheel with these value ranges. Control software reads the profile so that you can work in colour, position and gobo instead of in raw numbers.

Profiles are specific to a model and often to a firmware revision, so a profile for the wrong variant is worse than no profile at all. HitLight drafts a profile from the manual when yours is missing, and that draft stays marked as a draft until you test the channels on the real fixture — see the fixture library.

What is a DMX mode?

A DMX mode is one of several channel layouts that a single fixture can be switched between. The same moving head might offer a 14-channel basic mode and a 32-channel extended mode that adds 16-bit position and per-pixel colour. The mode decides how many channels the fixture consumes and what each of those channels means.

The fixture and the software have to agree on the mode. A light set to 14 channels but patched as 32 will read the wrong channel for everything after the first mismatch, which is the single most common reason a fixture does something inexplicable. Check the mode on the unit when you patch it.

What is a scene in lighting?

A scene is a saved look: a stored set of channel values for some or all of the rig that you can recall later. A scene can be static, like a warm front wash, or it can hold several steps that run in sequence with a fade time between each one, which is how chases and colour cycles are built.

HitLight edits scenes in a matrix — steps down the page, fixtures across it — and every cell is editable by hand: colour, intensity, position, gobo. The assistant can fill cells in, and you can overwrite anything it writes. You can build and watch a whole scene on the 3D stage before buying an interface; see supported hardware.

What is a cue?

A cue is a scene plus the instructions for how and when it runs: its fade time, any wait before it starts, and whether it advances automatically or holds until the operator acts. Theatre works in cues because a show is a sequence of specific moments, and each moment has to arrive on a particular line at a particular speed.

GO is the word for the operator firing the next cue, and it is the only control a lot of shows ever need. The cue worth rehearsing before an audience arrives is the one that takes the rig down — see lighting safety.

What is a cue list?

A cue list is an ordered sequence of cues that you step through live, one press at a time. GO runs the next cue, BACK returns to the previous one, and individual cues can carry their own wait and auto-advance so that parts of the sequence run themselves. It is the standard way theatre, musicals and structured live sets are operated.

HitLight chains saved scenes into cue lists with per-cue waits and auto-advance, and GO can be bound to a MIDI footswitch so a whole set runs without touching the laptop. A cue list can be built and rehearsed on the 3D stage before any interface is plugged in — see supported hardware.

What is a palette in lighting?

A palette is a named, reusable value — a colour, a position or a gobo selection — that scenes reference instead of storing the raw numbers themselves. Edit the palette and every scene using it changes with it. Positions are the usual example: re-point "centre stage" once after the rig moves and every cue that referenced it is correct again.

HitLight supports colour, position and gobo palettes, and editing one updates every scene that uses it. Position and gobo palettes are fixture-specific by nature, because they depend on the channels in the profile you patched — see the fixture library.

What is a gobo?

A gobo is a metal or glass disc with a pattern cut or etched into it, placed in front of a light source so the beam projects that shape. Gobos give you breakup textures, leaf patterns, logos and the hard-edged shafts that read as beams in the air. On a DMX fixture they sit on a wheel and are selected by value range on a gobo channel.

A second channel usually rotates the chosen gobo, and larger fixtures carry two wheels that can be layered. Which gobos a fixture actually has is part of its profile, which is why the HitLight stage preview can draw the real pattern rather than a generic disc — see the fixture library.

What are pan and tilt?

Pan and tilt are the two channels that aim a moving light: pan swings the fixture horizontally, tilt rotates the head vertically. Ranges vary by model — 540° of pan and 270° of tilt is common — and neither is standardised, so the same DMX value will point two different fixtures in two different directions.

Many fixtures offer 16-bit pan and tilt, which pairs a coarse channel with a fine one for smoother slow movement at the cost of two extra channels. Whether those fine channels exist depends entirely on the profile and mode you patched — see the fixture library.

What do HTP and LTP mean?

HTP and LTP are the two rules for deciding what happens when more than one source controls the same channel. HTP means Highest Takes Precedence: the largest value wins, which is what you want for intensity so a second look can add light but never steal it. LTP means Latest Takes Precedence: the most recent value wins, which is what you want for colour, position and gobo.

Most desks apply both at once — HTP for intensity-like channels, LTP for everything else — which is why bringing up a second scene brightens the stage instead of replacing it. HitLight merges simultaneous scenes the same way. Whichever rule is in play, Blackout overrides all of it; see lighting safety.

What is a blackout?

Blackout is a control that takes every channel to zero immediately, killing all output at once. It is the panic button of a lighting desk: it does not fade, it does not ask for confirmation, and it does not care what is playing. Every operator should know where it is before the room fills up.

In HitLight, Blackout sits beside the Auto toggle and takes effect at once. Stop instead holds the last safe look on the rig, and Fade Out takes everything down over one second. Press Blackout once at every venue to confirm it is wired correctly — see lighting safety.

What is Art-Net?

Art-Net is a protocol that carries DMX512 over an ordinary Ethernet network. Rather than a USB adapter, the laptop sends universes as network packets to a node near the rig, which converts them back into DMX on an XLR socket. Art-Net was published by Artistic Licence, is royalty-free to implement, and carries many universes down one cable.

HitLight outputs Art-Net from the macOS app and never charges per universe. If you are deciding between the two network protocols, Art-Net vs sACN covers how they differ and when each one is the better fit.

What is sACN?

sACN is a protocol that carries DMX512 over an ordinary Ethernet network, standardised as ANSI E1.31. It does the same job as Art-Net and differs mainly in defaults and governance: sACN is multicast by default, carries a priority field so two sources on one universe resolve predictably, and is a published ANSI standard rather than a vendor specification.

The fixtures never see the difference, because a node converts either protocol into the same DMX512 signal. HitLight outputs both from the macOS app; see Art-Net vs sACN for which to pick on a given network.

What is a DMX node?

A DMX node is a small box that converts network lighting data back into DMX512 on an XLR socket. It sits near the rig with an Ethernet cable running to it and one or more DMX outputs coming out of it. Nodes range from single-universe pocket boxes to rack units with eight outputs and a display.

Experienced operators tend to prefer a node over a USB adapter, and the reason is usually mechanical rather than technical: a node gives you a locking connector, and a USB plug can be kicked out of a laptop. The interfaces HitLight supports are listed on supported hardware.

What is a strobe channel?

A strobe channel makes a fixture flash rather than hold steady, with the DMX value setting the rate. Most fixtures put strobe on their shutter channel: a low range holds the shutter open, a middle range flashes progressively faster, and the top of the range is often a random or pulse effect. Dedicated strobe fixtures do the same thing far brighter.

Strobing is the lighting effect most likely to harm someone, which is why venues post photosensitivity warnings. HitLight's Auto Show will not drive flashing strobes or blinders at all — those channel types are removed from every automatic path in code, not by convention. See lighting safety.

What is haze, and how is it different from smoke?

Haze is a fine, even suspension of particles in the air that makes light beams visible. Without it, a moving head aimed over a crowd is an invisible line with a bright spot at the end; with it, the beam itself becomes the effect. A hazer produces a thin persistent atmosphere, while a smoke or fog machine produces thick visible clouds that dissipate faster.

Haze is also the thing most likely to trip a venue's smoke detector, so ask before you run one. HitLight's Auto Show will never fire smoke, haze, fans or flame: those channels are stripped from every automatic path in code, so it cannot reach them even by accident. See lighting safety.

Last verified 1 August 2026.