Introduction
DMX
DMX512-A or Digital Multiplex, is a protocol used for controlling a variety of different fixtures/equipment that can all be controlled within a single chain of communication. Otherwise called a universe.
There’s a lot more that can be talked about for DMX, but that’s not what this document is about.
How We Use DMX
At RIT, as of currently, the only streamline way we are able to utilize DMX is using the ETC Colorsource 40. A simple DMX controller made by ETC. It has 40 faders and is capable of communicating with a single universe. The board works great, and is lovely tool to have on set.
CRMX
Though, in the film industry, there is a growing popularity in a much newer protocol called CRMX, by LumenRadio.
CRMX (Cognitive Radio MultipleXer) can simply be thought of as DMX, but wireless.
However W-DMX/Wireless DMX is also a standalone protocol. Wireless Solution was the original owner of W-DMX, but LumenRadio gobbled up Wireless Solution and now also own W-DMX.
CRMX is a pretty fantastic protocol that’s lightweight and offers super solid reliability. Having the option of being able to control all of your lights on set at a single mobile station with barely any prep work is one of those things that make you question why you’ve never done this sooner. Then you look at the price tag of a single transceiver and immediately remember.
The Issue
At RIT, we don’t have any CRMX solution, but are flooded with lights that support the DMX protocol. One light worth mentioning specifically is the ARRI SkyPanel. There’s a special trick these lights have that we’ll circle back to.
The Solution
sACN/Art-Net
sACN and Art-Net are UDP based DMX-512 protocols. Meaning, they communicate through IP (Internet Protocol) packets, like WiFi or Ethernet LAN. However they are able to transfer MUCH more data. A single DMX512 cable is capable of handling a single universe, or 512 channels. Art-Net IV is able to handle 32,768 universes. Which is 16,777,216 channels.
These IP based protocols are heavily used in any facilities that need to communicate with and control a large number of fixtures. A node/gateway is a device that is able to map a DMX512 universe connection and translate that to a IP based connection.
These node/gateways can be dedicated rack-mount hardware with 8 DMX512 receptacles, and a IP based connector such as RJ45 or something fiber based like SFP. Nodes/Gateways can also be smaller boxers with a DMX512 port or 2, or some fixtures such as ARRI SkyPanels for our use case, are actually capable of acting as a gateway. Featuring an RJ45 port, as well as DMX in/out. We can connect our SkyPanels to the network, and not only control them directly via sACN/Art-Net, but also send data out of their DMX out port, to control other nearby DMX devices that don’t have sACN/Art-net connections.
Communicating with these devices
Ok cool. These devices act as gateways, but what value does that add besides being able to give us much more bandwidth? Well, just like our phones, TV’s, laptops, and many other devices that utilize the internet, wireless IP communication hardware is available at a cheap cost, with great reliability. A simple router/access point is able to send data at high speeds with decent range.
Talking to SkyPanels
Our first issue with attempting to communicate with SkyPanels wirelessly, is that they have no wireless NIC’s (Network Internet Connector) they feature an RJ45 port, but that’s it. One could connect the SkyPanel to the router/access point directly if it has a LAN port on the device, but that would limit us to only being able to talk to SkyPanels that are right next to the Router, which isn’t ideal, especially if we want to wirelessly talk to more than 1 device. A cheap workaround I found is using a WiFi repeater. WiFi repeaters are usually used for home networks where more range is required than what your access point can provide. Most of these repeaters, also tend to feature an RJ45 port, which is perfect for our use case! We can preconfigure multiple repeaters to listen for a set SSID, and use the RJ45 port to connect our SkyPanels to the network as if it was hardline via LAN.
Talking to all other fixtures
As previously mentioned. Once we’re able to communicate with our SkyPanels, we’ll then be able to use the DMX out port on the SkyPanel and send that to a