Every device to be controlled by DMX has to have a unique "base address". it is this "addressing" feature of DMX that enables it to work. The DMX address of a device is configurable by the lighting director so he knows where in the DMX map a particular device will be located. It also allows the devices on the network to ignore data that isn't meant for them by examining the destination addresses of DMX instructions and only acting if the address matches their address. Each device is connected in a daisy-chain fashion and the last device on the chain must be fitted with a terminator.

Consider a large rig with a mixture of conventional lights controlled by ordinary dimmers and colour scrollers with a smoke machine thrown in for good measure.

The console operator wishes to control all of the devices from one desk; his first task is to work this out on paper. Once he is happy with the addresses, he asks one of the riggers to set the DMX addresses up as follows (all devices require only one DMX channel in this example, but when some type of intelligent light are used, this is not the case):

• 48 dimmers, to be based at DMX address 0 through 47
• 20 colour scrollers, to be based at DMX address 48 through 67
• 1 smoke machine to be based at DMX address 68

He will then have control of each individual device. It is a simple matter for the console operator to set groups of lights and scrollers using the console soft patch. The smoke machine, being the last on the daisy chain, must have either an integral terminator or a terminator fitted to it's DMX out port.

It is possible, using opto-isolated DMX splitter units and merge units to have separate consoles for controlling the scrollers and the dimmers sharing the same DMX line. As long as there is no address conflict, the system will work perfectly.