Relable DMX setup and Best Practices

A few tips to help create a reliable DMX setup

Up to 32 devices

Up to 32 devices may be connected in a daisy-chain, with a terminator on the last device.

Using a DMX splitter/repeater (opto-isolator) can extend both cable distance (as the signal is regenerated and re-transmitted) and the number of devices (up to 32 per branch)

Up to 100 meters

DMX can only travel up to 100 meters before the signal weakens.

5-Pin XLR Plugs

DMX officially supports 5-Pin XLR DMX cables only. However there are readily available 3-pin XLR converters, but it is important to ensure these are DMX compatible (correct pin-out).

DO NOT USE Microphone/audio Cables

Many people often substitute cheaper balanced audio cable (regular microphone cable) with tragic results.

Audio cable cannot support the signal rate required by the high speed DMX protocol.

While the signal may pass over short distances, it is highly susceptible to interference and degradation, causing unpredictable results (such as blinking lights, confused intelligent fixtures, etc.).

Use DMX Terminators

If you have setup 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 back into the cable and degrade the data.

A terminator simply places a 110-120 Ohm, 0.5 Watt resistor across the two transmission wires.

Isolate DMX from power

Connect all smart lights to a separate mains which is isolated from the dimmer racks or computer or the audio power amps.

Unexpected events might occur if the mains line gets overloaded, and that might affect your DMX control gear.

Importance of Isolated Splitter

Use an opto-isolated splitter wherever you can to protect your DMX control gear from any unwanted voltage spikes.

Non-isolated dmx control devices must always be protected, otherwise they run the risk of being subject to sudden voltage spikes and might not survive.

 

From <http://www.enttec.com/support/kb/article/104-A-few-tips-to-help-create-a-reliable-DMX-setup