DMX512 (Digital Multiplex) is a standard for digital communication networks that are commonly used to control stage lighting and effects. It was originally intended as a standardized method for controlling light dimmers, which, prior to DMX512, had employed various incompatible proprietary protocols. It soon became the primary method for linking controllers (such as a lighting console) to dimmers and special effects devices such as fog machines and intelligent lights. DMX has also expanded to uses in non-theatrical interior and architectural lighting, at scales ranging from strings of Christmas lights to electronic billboards and stadium/arena concerts. DMX can now be used to control almost anything, reflecting its popularity in theaters and venues.
DMX512 employs EIA-485 differential signaling at its physical layer, in conjunction with a variable-size, packet-based communication protocol. It is unidirectional.
DMX512 does not include automatic error checking and correction, and therefore is not an appropriate control for hazardous applications, such as pyrotechnics or movement of theatrical rigging however it is still used for such purposes regardless. False triggering may be caused by electromagnetic interference, static electricity discharges, improper cable termination, excessively long cables, or poor quality cables.
Developed by the Engineering Commission of United States Institute for Theatre Technology (USITT), the DMX512 standard (For "Digital Multiplex with 512 pieces of information") was created in 1986, with subsequent revisions in 1990 leading to USITT DMX512/1990.