Protocols Explainer

In Expert, fixtures can be patched to DMX, eDMX (Art-Net, sACN or KiNET) or DALI.

DMX - A DMX universe which contains 512 channels; most fixtures will use multiple channels depending on their functionality. For example, a standard RGB LED will use three channels, one for red, one for green and one for blue, whereas a pure white LED will only use a single channel; one for intensity. Each channel can go from a value of 0-255, which then determines the intensity of that parameter.

Each fixture in your project will have two bits of information that are essential for Expert to be able to drive the fixtures; a start address, and a footprint. The start address will simply be the first channel that the fixture takes, and the footprint is how many channels the fixture needs; for example, an RGB LED will have a start address of 1 and a footprint of 3, so will listen to channels 1, 2 and 3. The next fixture will have a start address of 4 and a footprint of 3, and will listen to channels 4, 5 and 6, and so on. For a single RGB LED, if the Expert Control were to output 255, 0, 0, the fixture would turn red. If we adjusted the output to be 255, 0, 255, the fixture would be purple. With DMX, all channels in the universe are then sent out on every refresh, allowing for smooth transitions from one colour to the next and enabling dynamic lighting effects.

eDMX (Art-Net, sACN, KiNET) - eDMX is, in principle, the same as DMX. It works with the same concepts of universes and channels, each controlling a different parameter for a fixture. However, the protocol is instead output through the Ethernet port of the Expert Control, which will then be converted back into DMX data by an eDMX node on the network.

There are some key differences between each available eDMX protocol:

  • Art-Net - Art-Net, developed by Artistic Licence, will broadcast up to the first 30 universes. If more universes are output, then the protocol will switch to unicast, therefore sending the data directly to the IP address of a node that will output the Art-Net data. To do this, the Expert Control will send out a ArtPoll message. Each node would then respond with information on which universe(s) it is looking for, and the Expert Control would then send just that universe to that node. Art-Net also supports RDM in the same way as DMX.

  • sACN - sACN, developed by ESTA, uses multicast to communicate with the nodes. This means that each node will only have to listen to the specific IP address for the universe it takes its data from, which reduces network strain compared to broadcast for Art-Net. sACN can also support HTP merging depending on the node.

  • KiNET - KiNET, developed by Philips Color Kinetics, is a system developed to combine power supplies and eDMX nodes in one. Instead of X number of universes added, power supplies are added from the network which provide a certain number of ports which can then be patched to.

DALI - DALI is also patched within the Patch tab, although it functions in a different way to DMX. DALI is patched via ballasts, which can contain all of the fixture's functionality. An RGBWA ballast or a white ballast will still only take up a single patch point, but the system is limited to 64 ballasts on a single port. A key difference between DMX and DALI is that DALI will only send commands on a change, such as “Go To White 254”. This is useful for functional lighting, but disallows DALI from functioning in a dynamic way.