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What is ArtNet?


This page is for people who have no idea what DMX and/or TCP/IP is. If you already know, you'll find the following pretty basic.

ArtNet is a protocol for sending DMX data over IP networks. In order to understand ArtNet it helps to know a bit about DMX and IP, so here it goes....

This page is constantly under construction. I never got around to finishing it.

What is DMX?

DMX is a standard for controlling theater equipment (mainly lighting). In a theater, there are normally large numbers of lights, that have to be turned on and off independently. One solution to this is to wire the theater like a houseand have a desk of on/off switches with a mains cable running to each light.

There are a couple of issues with this however. First, mains cables are relatively thick, even with 20 lights and 20 cables, a lot of wire is involved. Secondly, if we ever wanted to move the desk, we'd have to run a new wire for every light which is most theaters would be a horrendous job. Finally, doing the same thing many times isn't the way we engineers like to work :)

So, instead of a cable from the desk to every light. why not put all the mains switching gear near the lights and run a low voltage control signal from the desk? Sounds good? Well thats exactly what DMX does.

DMX is a serial protocol, so it sends data one bit at a time over the wire. Each DMX cable can control up to 512 channels (for now, each channel is a light) and each channel takes a value between 0 and 255. If conventional lights are being used, each light occupies a single channel and the value of the channel is the intensity of the light (0 = off, 255 = full).

A DMX Cable

In a DMX cable, only 3 of the 5 pins are used (signal +, signal -, and ground). Although this cable is blue, it's not CAT5!

Example of a DMX control desk

A DMX network is formed in a daisy chain fashion, so one device is the source (most often the lighting control console) and the other devices are the receivers. Each receiver has a preset address, which corrosponds to the channels of DMX data (from 1 to 512) that it is interested in.

Daisy Chain Topology

What are IP Networks?

Like DMX, IP is a protocol. Where as DMX connects lighting equipment, IP was designed to connect computers. For the scope of this discussion, IP operates on top of another protocol called Ethernet. Ethernet cables are typically blue and have a plugs similar to phone connectors on the end.

Ethernet is wired in a star fashion (extended star to be precise), so an Ethernet network looks a bit like this:

Star Topology

ArtNet and DMX

Back to ArtNet. ArtNet then is a way of sending DMX information over IP networks. So what are the advantages ?

ArtNet was created by Artistic Licence and you can download the specification here