What is DMX in Stage Lighting?

DMX (short for DMX512) is the standard digital control signal used in live events to send instructions from a lighting desk to lights, dimmers, haze machines and other effects. Nearly every piece of professional lighting equipment accepts DMX, which is why fixtures from different makers can all run from the same desk. It was first developed in the 1980s and is still the industry standard.

How DMX works

A DMX system is set up in five steps:

  1. Plan universes: each DMX universe carries 512 channels; big rigs use many universes.
  2. Address fixtures: each light is given a start address so it knows which channels to listen to.
  3. Cable up: fixtures are linked in a daisy chain with DMX cable, ending with a terminator.
  4. Patch the desk: the lighting desk is told which fixture sits at which address.
  5. Program and run: the lighting designer builds cues that send DMX values to each channel.

DMX addresses and patch plans need to be shared with every lighting crew, which teams keep with documents in Crescat.

DMX vs Art-Net and sACN

DMX runs over its own cables, one universe per line. Art-Net and sACN carry many DMX universes over a standard computer network, which makes large rigs easier to run. Nodes convert the network signal back to DMX for each fixture.

What DMX controls

  • Dimmers and conventional lights
  • LED fixtures: intensity and colour
  • Moving lights: position, colour, gobos and effects
  • Haze and smoke machines
  • Some video servers and special effects
  • Practical lights on set
  • Some motors, fans and set automation

Frequently asked questions

What is a DMX universe?

One line of DMX, carrying 512 channels. A simple light may use one channel; a moving light may use 30 or more, so large rigs need many universes.

What cable does DMX use?

The standard calls for 5-pin XLR connectors, though 3-pin is common on smaller equipment. Microphone cable should not be used for DMX, as it can cause errors, especially over long runs.

Why does DMX need a terminator?

A terminator at the end of the chain stops the signal reflecting back down the cable, which can cause lights to flicker or behave oddly. It is a cheap part that solves many mysterious faults.

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