A simple guide to setting up your DMX fixtures and getting them to communicate with each other.

This guide will run you through the setting up of DMX fixtures in simple easy to follow steps.

1: To start with we are going to assemble the rig and set up the fixtures ready for operation, You need to connect all of the fixtures in a daisy chain fashion from one fixture to the next using the XLR inputs and outputs. If the last fixture in the line has a DMX termination switch it should be set to on, all other fixtures in the chain should have this switch in the off position. You will need to use a DMX termination plug for fixtures without a built in terminator, this is simply a male XLR connector with a 120 Ohm resistor between pins 2 and 3.

It is worth mentioning at this point that the order in which the fixtures are connected in the chain does not relate to the position on the desk.

The DMX start address sets where the controls are located amongst the 512 channels. Since the position of the fixtures in this chain don't matter you can connect the in the most convenient way, as in you could connect the fixture that is closest to the controller first yet it doesn't have to be controlled by the first set of channels.

2: Now you have all of the fixtures connected to each other, and one of those fixtures connected to the controller, you can select which out of the 512 channels you want to control your fixtures. This is done using the DMX Dip Switches, they can normally be located near the DMX Input and Output sockets. Generally there will be 10 DIP switches for setting the DMX address, these are set using binary. Each switch has a corresponding value, and the DMX address is calculated by adding together these values.

The numbers on the DIP switches correspond to the following values:

SWITCH VALUE
1 : 1
2 : 2
3 : 4
4 : 8
5 : 16
6 : 32
7 : 64
8 : 128
9 : 256
10 : N/A

Switch 10 will not normally be used for the DMX addressing, although may control other aspects of the fixture such as switching between DMX or stand alone mode, or may be used to switch in a termination resistor.

Notice then setting switches 1-9 to the ON position will give a maximum DMX address of 511. For most fixtures this is not a problem, remember that you are setting the start channel of the fixture, the only time you may want to set the channel to 512 would be in the case of a single channel fixture. Some fixtures may automatically add 1 to the DMX address, so that setting all switches to the off position puts the fixture on channel 1. One such example is the NJD datamoon, only having 8 DIP switches and adding 1 to the address to give a maximum start channel of 256.

Sometimes fixtures can take up a number amount of channels, for instance some fixtures may have more functions that others (e.g. some fixtures may have an iris or 2 colour wheels)

For example, the Chauvet Navigator takes up 4 channels:

Channel 1 = Pan
Channel 2 = Tilt
Channel 3 = Gobo/Colour Wheel
Channel 4 = Shutter/Strobing Function

The Martin Roboscan Pro 918:

Channel 1 = Shutter/Strobing
Channel 2 = Dimmer
Channel 3 = Colour Wheel 1
Channel 4 = Colour Wheel 2
Channel 5 = Gobo wheel
And so on.......

As you can see from above different fixtures can have a different amount of channels and the channels are assigned to different functions. Keeping this in mind, we can now proceed with setting the dip switches.

When we set the dip switches we set where channel one is located (Channel 1- Channel 512) and all the other channels will come after channel one what ever order they are in.

So, if we put dip switch one ON and keep the rest off on the roboscan 912, slider one on our controller will be shutter and channel two will be dimmer and so on.

If we want our fixtures channels to start on channel (slider) 18 we can do this by putting switch 2 and 5 down, this will mean that the values of both of the switches will add up to 18, meaning that now shutter will be on 18, dimmer will be on 19 and so on.

You can set any of your fixtures in you chain to start on different channels meaning that you can control them individually, alternatively you can also have more than just one fixture on one channel, you can group fixtures together and control them with the same sliders.

One thing that commonly confuses people is what happens if you set say one roboscan 912 on channel one and then a second roboscan on two, all that will happen in this case is that every time you use the dimmer on fixture one the other fixture will begin to strobe, to operate fixtures successful it is important that you separate them according to the amount of channels (or functions) the fixture has. If you have a fixture on channel 1 that uses 5 channels, the next fixture should start on channel 6.

Note that the Roboscan 918 was only used as an example, it could be any DMX fixture and similar principles would still apply.