DMX512 is a technical specification for a specialized digital communication network system created in 1986 by the United States Institute for Theater Technology. The system was designed with the intention of creating a standardized way of managing theater lighting devices such as light controllers and dimmers. Since its inception, however, it has also become the standard for controlling other theater-related devices such as special effects devices. A typical system consists of a controller device and any number of slave devices required by a given theater production such as moving lights, spotlights, or fog machines.
Following its creation, the DMX512 standard was updated several times until in 1998 the Entertainment Services and Technology Association revised it as an American National Standards Institute (ANSI) standard for use across the United States. The resulting standard was approved by the ANSI and titled “Entertainment Technology, USITT DMX512-A, Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories.” Since the initial creation of the ANSI standard, it has been further modified to include newly developed technologies and is currently titled “E1.11, USITT DMX512-A.”
In practice, a DMX512 network uses a controller, such as a lighting control panel that conforms to the standard, and a series of devices connected with cables one to another in a daisy chain. Each device has an “in” port that is used to control the device and an “out” or “through” port that connects to the next device in the chain. The last device in the chain has a special termination plug installed to close the network into a segment called a “universe.” In some more advanced systems, there are specialized control panels capable of controlling several “universes.”
The DMX512 system was originally designed to be a “cabled” system; however, due to the advent of wireless technologies, newer versions of the standard have included WiFi as a method of controlling devices. In these systems, the controller sends its signals over its standard cable to a special WiFi transmitter where they are converted to WiFi signals and transmitted. Special receivers that convert the signal back to the standard DMX512 format then pick up the WiFi signals, perform the conversion, and send them to the “in” ports of the devices to be controlled.
In an effort to keep the DMX512 networking system current, in 2006 a new bi-directional communication protocol was approved for the system. The new protocol allowed the slaved devices to send signals back to the controller for the first time, greatly enhancing the system and the types of devices it is able to control. With the addition of the Lightweight Streaming Protocol approved in 2009, the system continues to grow in complexity and capability.