DMX512

is a standard of lighting control that was developed by the

US Institute of Theater Technology

(USITT). This standard was originally developed to control

light dimmers

, but is currently being used to control just about every aspect of

lighting

, from color changes, to light motion, to

fog machine

s, and even lasers.

DMX512 lights

are specially designed to work with this standard, although most any light can be made to work by using

DMX512

controlled

dimmer pack

s or relays.

In the

DMX512

method, each

light

has an address and "listens" to a control cable for commands that are sent to its address. Addresses are generally set on the

light

by a series of DIP switches. Note that one

light

may have multiple addresses. For example, a

color changing light

may have one address to set the mode of the

lamp

(on/off/

sound activated

), another address to select the color, and a third address to set the speed at which it changes the color. When the address of the

light

is set by DIP switches, the first address of the

light

is being set and the others will be offset from the first. For example, if a

light

has three addresses and the DIP switches are set to address 15, the light will be using addresses 15, 16, and 17.

When a command is sent to its address, the

light

will respond to that command. A

DMX512 light

will have a

DMX

description table that describes what every command does. For example, a value of 0 might turn off the light, 10 might make it red, and 255 might make it blue. Note that more than one

light

may be set to the same address. If this is the case, when a command is sent, all of the lights with that address will respond. In this way, many lights can be controlled in synchronization using only one

DMX512 address

.

The

DMX512 protocol

is capable of controlling up to 512 addresses per "universe", however most

controllers

only provide a subset of this. Each universe represents a separate control line. Each control line is connected to the

lights

in a "daisy-chain" manner, whereby the

controller

is connected to the first light, then the second light is connected to the first, and the third is connected to the second, etc. The last light in the chain must be terminated with a small plug in resistor device to keep the signal from reflecting from the end and interfering with the transmitted signal. If it is inconvenient to run the control line in one straight run,

DMX512 splitter

s exist. It is important to use these rather than to just make a "Y" cable, as the signal levels will not be correct and the reliability of the

lights

will be compromised.

The

DMX512 protocol

is designed for speed and simplicity. Therefore, no error checking is done, and as such,

DMX512

is not appropriate for controlling potentially dangerous equipment such as pyrotechnics. However, for

stage

and

theater lighting

,

DMX

512 is easy to use, is fast enough for most applications, and is capable of producing spectacular large-scale

light shows

.

DMX

512's acceptance by the industry is shown by the large number of devices that are available that use the

DMX512 protocol

.