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DMX or DMX512, short for digital multiplexed signals (at 512 channels per data network), is the name given to the standard implemented by USITT that set regulations for the previously unmonitored processes of transmitting data from lighting controllers to the onstage lighting equipment.

History
Before USITT implemented the requirements defined by DMX512, the control systems for lighting arrangement varied by company and manufacturer and featured almost no cross-compatibility. Entire lighting arrays would have to depend on the same company over its lifetime, as a control board from one company would be incompatible with the connecting cable of another and the dimmer pack of a third.

As productions became more and more technically involved, the demand for cross-compatible parts grew and a common system became a necessity. In 1986, the USITT Engineering Commission began discussions on what would become a universal standard for lighting control. In 1986, the commission produced "USITT DMX512 - Digital Data Transmission Standard for Dimmers and Controllers" which, with minor corrections in 1990 and 2004, would remain the definitive standard for the controlling technical lighting over the next 30 years. By requiring strictly regulated aspects of a lighting system, from the cable connectors to the signal structure, DMX created a unified industry that could be easily transferred from one show and one location to another.

System configuration
DMX systems are the figurative nervous system of an entire lighting arrangement, connecting the governing light board or other controller to the lighting entities and transferring the necessary data. However, DMX line does not provide power for the lighting equipment; electrical power is typically run separately from a different source using different line. The sole purpose of DMX line is the transmission of data.

Historically, a control board or booth will create and send commands to a dimmer pack, which moderates how much or how little power is sent to a light and therefore affecting its intensity. However, modern stage lighting has developed to a level of complexity where many more degrees of control are necessary, such as a light's color, gobo shape, and three-dimensional orientation, in addition to the brightness. This technology urged the gradual phasing out of dimmer packs in favor of built in controllers for each light or lighting element. In this more recent setup, each light is connected directly to both a main power supply and the DMX control system operated by the light board. Instead of a dimmer pack determining the brightness of a light, the internal controller reads the incoming DMX signal and adjusts not only the lights power output but also any other necessary means of adjustment, such as the motors responsible for 3D rotation and the internal color wheel.

Signal
As hinted by its name, DMX512 gets its name from its ability to control 512 separate channels of information using one cable. Although originally designed with the intention of potentially controlling 512 dimmers, the previous section outlines that modern theatrical lighting is simply too complex to be controlled with one input. However, this obstacle was easily overcome by assigning multiple channels to every light. In fact, a single light may require 7 different channels, one each for the brightness of the light, its color, gobo shape, its general and specific orientation on both the x- and y-axes.

The control unit for a DMX system will monitor and broadcast the status of each of the 512 channels repeatedly, essentially creating a constant stream of data with instructions for every adjustable characteristic for every light attached to the specific chain of DMX. Different lights and their internal controllers respond only to certain channels, allowing data intended for devices farther down the line to pass by without affecting all the devices before it. Additionally, this quality gives DMX a very reliable characteristic: if any signal is by chance misinterpreted by a device hooked up to its chain, an accurate command will replace the old one nearly 60 times every second, nearly eliminating error caused by interference with the cable.

Physical elements
The most visibly identifiable characteristic of a DMX system is the 5-pin XLR connectors found at each end. Required by USITT standards, these connectors are almost solely used by DMX systems; although XLR connectors can be found on nearly every theatrical sound system, these cables use the more industry-standard 3-pin XLR, or XLR3. The XLR5 used by DMX is what allows for its high level of functionality: This allows DMX cable to both send its continuous stream of 512 bits of information on one set of pins while simultaneous receiving information about any elements with sensors that provide active feedback. However, it should be noted that the capabilities of this secondary stream of information are seldom used in a controller system.
 * The first pin acts as the electrical ground for the cable.
 * Pins two and three act as the positive and negative components for the system's controlling communication.
 * Pins four and five are the positive and negative components for "secondary communication," or any information sent from the elements back to the control.

Uses
DMX cable is the most commonly used system for theatrical lighting. Whether dealing with simplistic monologue or the complex visual effects in modern opera, the lighting elements are almost guaranteed to be controlled using the DMX512 standard.

However, DMX also has applications outside of theater, made possible by the development of wireless DMX technology. Although regular DMX cable can be reliably run up to 1500 feet without the use of amplification, the truly unrestricted nature of wireless mechanics further broadens the usefulness of the standard. Even though wireless systems have allowed world-tour concerts of almost 30,000 to locate lighting control over 600 feet from the stage (freeing up valuable stage space from what could become miles of wire), the most notable is the expansion DMX has seen into elements of architectural design. Whether drawing attention and pride to a cultural building with elaborate light schemes to illuminating and even inspiring the grandeur of single most expensive casino, the potential of DMX outside the theater industry is rapidly expanding.