DMX512, short for Digital Multiplex 512, is the protocol which digitally manages up to 512 channels via a single data cable. A group of 512 channels is referred to as a Universe. DMX is electrical pulses that travel along the data line, linking a series of fixtures in a "daisy-chain" configuration.  

In the DMX512 framework, each channel comprises a range of 256 steps (0-255), which are allocated to various attributes in lighting fixtures. These attributes encompass a broad spectrum, including colours like red, green, and blue, as well as attributes such as intensity, and pan/tilt positioning. Your lighting fixtures will need to be addressed to a channel or group of channels.

There are some limitations when it comes to using DMX, though some of these can be overcome by using DMX Splitters.

Follow these helpful rules while using DMX:

  1. Up to 32 devices may be connected in a single daisy chain, with a terminator on the last device. Using a DMX splitter/repeater can extend both cable distance (as the signal is regenerated and retransmitted) and the number of devices (up to 32 per branch). We recommend adhering to a more conservative limit of around 16 fixtures per cable run. 
  2. Up to 300 meters, DMX cable should be run to a maximum of 300 meters between the DMX source (controller) and the last fixture, past this, the signal can degrade. A splitter or booster can extend this run.
  3. Cabling should be either DMX cable (not Microphone/audio cables due to a lower signal rate) or Cat6 cable. DMX can be terminated to either 5-Pin XLR, 3-Pin XLR, RJ45 connector or Screw Terminals ensuring the correct pin-out is followed. 
  4. Never Y-Split DMX Data: DMX data should never be Y-Split to stop data bounce back or clashes. – Always use a DMX buffer or splitter. 
  5. Use DMX Terminators If you have set up your devices in a daisy chain: the final device in the daisy chain must be terminated. The terminator absorbs signal power which would otherwise be reflected into the cable and degrade the data. A terminator simply places a 110-120 Ohm, 0.5 Watt resistor across the two transmission wires. 
  6. Isolate DMX from power Connect all intelligent lighting fixtures to a separate mains power source where possible that is fully isolated from the dimmer racks or computer or the audio power amps. Unexpected events might occur if the mains electricity gets too much electrical “noise” on it that might affect your DMX control gear. 
  7. Importance of Isolated Splitters Use an optoisolated splitter to protect your DMX control gear from any unwanted voltage spikes that could potentially make their way into the DMX line. Non-isolated DMX control devices must always be protected, otherwise they run the risk of being subject to damage caused by sudden voltage spikes.