DMX is an acronym for Digital Multiplex.
It is the standard digital communication protocol that is used to remotely control intelligent lighting fixtures. Originally created in 1986, the standard has continued to be used and developed as the standardised communication protocol for controlling intelligent lighting fixtures.
Intelligent Lighting Fixtures
The expression “Intelligent lighting fixtures” covers a wide range of fixtures with varying aspects able to be controlled remotely from a console or desk. Basic LED fixtures with colour control, right through to the more complicated fixtures with movement and a large array of effects such as prism, gobos, colour mixing and more.
The DMX Controller
The brains of the DMX is the controller (a desk, console or playback). The DMX controller broadcasts DMX in universes; a universe is 512 channels of DMX. Most fixtures within the network will take up more than one channel; some will take almost a whole universe.
A DMX controller will likely be split into sections:
- Fixture selection section
- This may be fixed in a basic controller but will need to be set up (patched) in a more complicated console.
- Groups of fixtures can be selected in this section.
- Attribute control, colour, movement, effects…
- Playback selection
- Chases, memories, cue stacks can all be controlled here.
Due to limitations of space, there is a high chance that these sections will utilise the same buttons, faders, wheels, and increasingly, touch screens are utilised to display information in the more complicated consoles. Additional external monitors are an option to increase the information displayed to an operator as the complexity increases.
DMX Cabling & Connectors
A lighting controller or console is used to manage a network of lighting fixtures, working in a master–slave(s) relationship. These slave fixtures are linked in a series to the console, one to the next to the next, in what is commonly called a daisy chain. Typically, a DMX cable will use a 5-pin XLR connector, though usually the cable is only three cores: positive, negative and shield/ground. To avoid data problems, you should use a special XLR plug called a terminator to end the chain. Some equipment can use 3-pin XLR connectors for DMX; however, this can lead to confusion with audio cables that more commonly use 3-pin XLRs.
DMX Addresses
All the fixtures need to be given an address. For individual control of fixtures, they need to have different addresses. There is no reason not to use the same address if you want the fixtures to do the same things. Each fixture takes up a space in the universe. If a fixture uses 11 channels and is addressed to 1, the next available address a fixture could use is 12.
Other Uses for DMX
Although DMX is primarily used for entertainment lighting control, it is also used for control of smoke and haze machines. Even video content can be triggered using DMX, as well as an increasing amount of home lighting which has incorporated DMX with the rise of LED lighting. DMX should not be used for pyrotechnic effects or any potentially hazardous effects.