How DMX512 works

If you're completely new to DMX, read our "What is DMX" page first. This explains some of the background.

What is it?

How do you transmit it?

How do you receive it?

What problems need to be avoided?

DMX will often continue to work with one of the A or B legs disconnected, if the 120 ohm termination is not fitted. If you get a situation where the system works without a terminator but not with a terminator, chances are there's a break in one of the lines somewhere.

DMX devices are fairly resistant to "bad" things being connected. However, some DMX connectors are similar to audio - you can guess what happens next. Also if there is a mains fault to earth (the fault may not necessarily be in any of the DMX equipment), the fault current can flow down the DMX cabling damaging the fixtures.

DMX over ethernet

A lot of bigger control consoles can send out the DMX over ethernet. This allows multiple universes of DMX to be sent over one wire. The DMX-over-ethernet will usually be converted back to normal DMX near to the fixtures to be controlled (though a number of fixtures can now connect to the ethernet directly). In effect the ethernet is used as a distribution system, going back to normal DMX at the destination.

Unfortunately there is not yet a common standard for DMX over ethernet so you have to stick with one manufacturer. Artistic Licence have published their standard "Art Net" in the hopes that it might help establish a common standard.

Further reading

We recommend the booklet "Recommended Practice for DMX512" by Adam Bennette, published by PLASA. It's available here.