It was originally intended as a standardized method for controlling stage lighting dimmers, which, prior to DMX512, had employed various incompatible proprietary protocols.

DMX512 uses a unidirectional EIA-485 (RS-485) differential signaling at its physical layer, in conjunction with a variable-size, packet-based communication protocol.

DMX512 does not include automatic error checking and correction and therefore is not an appropriate control for hazardous applications,[1] such as pyrotechnics or movement of theatrical rigging.

The DMX standard is published by the Entertainment Services and Technology Association (ESTA), and can be downloaded from its website.

A DMX512 network employs a multi-drop bus topology with nodes strung together in what is commonly called a daisy chain.

Some DMX slave devices have built-in terminators that can be manually activated with a mechanical switch or by software, or by automatically sensing the absence of a connected cable.

If more than 32 unit loads need to communicate, the network can be expanded across parallel buses using DMX splitters.

Network wiring consists of a shielded twisted pair, with a characteristic impedance of 120 Ω, with a termination resistor at the end of the cable furthest from the controller to absorb signal reflections.

It is further recommended that receivers have a high impedance connection between signal common and ground; such ports are referred to as isolated.

The three-pin XLR connector is commonly used for DMX512, on lighting and related control equipment, particularly at the budget/DJ end of the market.

Use of the three-pin XLR in this context firstly presents a risk of damage to the lighting equipment should an audio cable carrying 48-volt phantom power be accidentally connected.

Three-pin XLR designed for audio applications rather than DMX512 communications may also lead to signal degradation and unreliable operation of the DMX network.

DMX512-A (ANSI E1.11-2008) defined the use of eight-pin modular (8P8C, or "RJ-45") connectors for fixed installations where regular plugging and unplugging of equipment is not required.

7.2 Equipment intended for fixed installation with internal connections to the data link Fixed installation products with internal connections to the data link may use the 5-pin XLR connector, but shall not use any other XLR connector.

The contact (pin) numbering on the alternate connector should match numbering for the standard 5-Pin XLR The 8P8C modular connector pinout matches the conductor pairing scheme used by Category 5 (Cat5) twisted pair patch cables.

The avoidance of pins 4 and 5 helps to prevent equipment damage, if the cabling is accidentally plugged into a single-line public switched telephone network phone jack.

When DMX512 was ratified, many of these manufacturers then issued firmware updates to enable the use of DMX512 control on their existing equipment by the use of a simple adapter to and from the standard 5-pin XLR style connector.

As the electrical specification currently only defines a purpose for a single wire pair, some equipment manufacturers continue to use it.

This resolved issues arising from the differences in requirements for cables used in touring shows versus those used for permanent infrastructure.

[8] The electrical characteristics of DMX512 cable are specified in terms of impedance and capacitance, although there are often mechanical and other considerations that must be considered as well.

The significantly lower impedance and higher capacitance of these cables distort the DMX512 digital waveforms, which in turn can cause irregular operation or intermittent errors that are difficult to identify and correct.

A start code of 0x00 (hexadecimal zero) is the standard value used for all DMX512 compatible devices, which includes most lighting fixtures and dimmers.

A maximum-sized packet, which has 512 channels (slots following the start code), takes approximately 23 ms to send, corresponding to a maximum refresh rate of about 44 Hz.

Earlier versions of this standard assumed that only dimmer class data would be sent using NULL START Code packets.

In practice NULL START Code packets have been used by a wide variety of devices; this version recognizes this fact.

Some of the more common symptoms of improper termination are flashing, uncontrollable or incorrect light operation, or other undesired random special effects.

Recently, wireless DMX512 adapters have become popular, especially in architectural lighting installations where cable lengths can be prohibitively long.

Many alternatives to DMX512 have been proposed to address limitations such as the maximum slot count of 512 per universe, the unidirectional signal, and the lack of inherent error detection.

E1.11-2004, a revision of DMX512-A, also lays the foundation for Remote Device Management (RDM) protocol through the definition of Enhanced Functionality.

An Ethernet-based protocol can distribute multiple DMX universes through a single cable from a control location to breakout boxes closer to fixtures.