Who doesn’t appreciate the power of Art-Net? Art-Net gives us the ability to manage massive amounts of DMX over a single cable with one controller? In turn, we can control a ton of fixtures easily from one place which makes programming shows much easier. However, while Art-Net is an amazingly cool method of control, it adds another hat to the lighting designer — Information technology administrator. Now, we not only need to think about which gobos overlap best, but also how to make sure that our network of fixtures is running smoothly.
Art-Net in a Nutshell
Art-Net is a TCP/IP protocol that allows you to send multiple universes of DMX (more specifically Art-DMX) information over a network-based topology. TCP/IP is an abbreviation for Transmission Control Protocol/Internet Protocol. Simply put, Art-Net functions much like a standard computer network does. This means that there is a standard CAT-5 RJ-45 (Ethernet) port on the back of you lighting controller that can output Art-Net protocol, then somewhere out in your rig, there is a router that you plug into from the controller and send information to it. That router then splits up the Art-Net signal and sends it to any number of devices including Art-Net ready lighting fixtures, or Art-Net to DMX converter boxes. All of these devices on the Art-Net network are defined as nodes. A node consists of any device on the network that is capable of sending, receiving, or forwarding information over a communication channel. For our purposes, this means that any device that translates Art-Net to DMX is a node on the network. Please note that this does not mean that if you plug in Art-Net into a fixture, the DMX ports then automatically output DMX. You need to consult the manual of the fixtures you are working with to see if this is possible. This is important to understand, as the way you approach communications setup with Art-Net is different than setting up a standard DMX network. All DMX fixtures have in and out ports, while many Art-Net devices only have input ports. This is because Art-Net uses a star topology. Star topology means that you can’t daisy chain devices together without passing through a network switch. If you look at a standard office network setup, you will see that it is a star topology — Computer to router, then router to printers, scanners, and fax machines. If an office network were daisy chainable, then you could go directly from the computer to each one of those devices, and they could be interconnected, but that is not the case. Fixtures such as the Magic R series from Ayrton and the Nexus series from Chauvet have network switches built into them so that even though the topology is still technically star, it is, in fact, possible to daisy chain Art-Net devices in this manner.
How Art-Net is Being Used Now
As an industry standard, most manufacturers are now developing with Art-Net 3. This is the latest version of Art-Net that has been released by Artistic License. This incarnation of Art-Net allows for the control of a theoretical 32,768 universes of DMX over a single cable. Pretty incredible if you ask me, but there are limitations of hardware that will hamper this ability to control so many universes. The first thing you need to know is what version of Art-Net your controller is capable of running. You then need to know if your controller is sending unicast (controller to peer) or broadcast (peer to peer) Art-Net. Broadcast, or peer-to-peer is an unmanaged network where multiple Nodes transfer data without the intervention of a controller. All data transfer uses Art-DMX packets. The limitation of broadcast is that in larger networks, it can cause information conflicts (or packet collisions), which shows up in lighting fixtures as operational delays or flickers. Unicast, or controller to peer, is the most sophisticated implementation whereby one or more Nodes communicate with one or more central controllers (lighting consoles). Unicast is preferred as it directs each node to communicate directly with the controller for its information. It is a much cleaner method of data transfer, with fewer opportunities for data conflicts or collisions.
Keeping Your Art-Net(work) Running Smoothly
When you are setting up your system there are a few things to keep in mind from the start. First, in Art-Net, your first universe of DMX is universe 0, not universe 1. This is an important point when you are setting up your network. If you are using standard DMX as well as Art-Net, it is important not to allow your universes to overlap. To avoid this is to make sure that you set your first universe of Art-Net above your standard DMX universes. For example, if you want to use the four universes of DMX from your console to run certain elements, no problem. Set your first universe of Art-Net (which in Art-Net is universe 0) to the first open physical universe on your controller. It is just important to be aware that you do have to take the extra steps to assign your controller to output Art-Net on the universes you desire. Every controller has a different way of setting up your ports, so be sure to actually read your controller’s manual. Someone took the time to write it, so take a moment to read it.
The table below helps to explain how this all works:
The idea of the chart to the left is to help you keep your DMX universes and Art-Net universes clearly managed. By using letters to define your universes, your paperwork will hopefully make more sense than trying to remember which universes are straight DMX and which are Art-Net. Keep in mind that if you are using an Art-Net to DMX box that has the ability to assign its output ports to different universes, using letters becomes much easier than trying to keep up with numbers. You might end up having both DMX and Art-Net devices in the same area of your rig. Universe A and Universe F make more sense than DMX universe 1 and Art-Net universe 1, especially if you are the one trying to keep it straight.
When it comes to assigning IP addresses to your devices, there are three methods.
(1) Static IP: This is the IP address that comes with your device. I recommend that you stick with the static IP method unless you are very technically savvy for reasons I will talk about below. (2) Manual: This is where you can manually input your own IP address. Keep in mind that all primary Art-Net IP addresses start in 2.x.x.x and the secondary IP address starts with 10.x.x.x . No other start codes are allowed. The Art-Net controller will automatically poll the entire system searching for these two start addresses. (3) DHCP, or Dynamic Host Configuration Protocol, is where you allow a DHCP server, such as a router to assign IP addresses freely.
It is important to note that Art-Net is specifically designed to be used in a closed network situation only. Art-Net is not designed to be used in conjunction with the Internet. On top of that, it is not a good idea to run Art-Net over a building’s internal network. Your lighting rig (or architectural installation) should run on its own isolated network. This, again, will help to make sure that there are fewer opportunities for your Art-Net network to have problems. So, keep your lighting network separate from your collection of YouTube videos of dancing kittens. Cute they may be, your lights don’t care.
If you do start to see your lights acting oddly under Art-Net operation, there are some troubleshooting tips to start with before you call the panic line at either your controller or fixture suppliers.
1: Know your system. Know how many nodes are attached to the Art-Net network. If you are using non Art-Net based fixtures, this means that you will need to use at least one Art-Net to DMX converters (such as the Net-X from Chauvet Professional or the Down Lynx from Artistic License). If you are using Art-Net enabled fixtures, you might want to consider using a controller that will support unicast. The larger your Art-Net system is, the more important it is to use unicast instead of broadcast. Even within a unicast system, it is important to be using 1 GB (1000baseT) routers with high quality throughputs. This is also something to be conscious of when you are using fixtures that have Art-Net in/outputs. These in/outputs also act as throughputs, and having low quality components in the fixtures can limit the amount of devices that can be linked together. This is similar to the idea that you can only link 32 DMX-based fixtures together on one line. Do your research on the gear you are planning on using. Also, keep away from off-the-shelf routers. Even though they may have 1 GB ports, they are not designed to work with systems that can’t afford to have data packets dropped. Knowing your limits will greatly improve your system.
The below table is taken from the user guidelines PDF from Artistic License (artisticlicence.com) which helps you to know what your universe limitations are based on your gear that you are using:
2: If you do have a high count of Art-Net devices and are using a broadcast based controller, and you are seeing flickers, try this trick — create a desk channel somewhere in one of your Art-Net universes that is not connected to anything (if channel 512 is not in use, this is a perfect choice). Build a macro assigned to this channel that constantly raises and lowers the value from 0-255. By running this macro, it ensures that no matter what, Art-Net is constantly being transmitted. This works because when the Art-Net system is idle between operations (between cue changes), no signal is being sent to the fixtures. By running this macro, it makes sure that signal is constantly being sent to all fixtures and keeps refreshing their information. Keep in mind that broadcast-based Art-Net is really only designed to support about 40 universes of DMX. Again, know your gear.
3: It is highly recommended that you use the static IP addresses that are pre-assigned to your nodes. Keep in mind that the IP addresses and MAC addresses that are pre-installed in your fixtures are designed to prevent overlapping IP addresses in your system. Every manufacturer of Art-Net products has a specific code that is imbedded in the MAC addresses that makes sure that products are unique.
Summing Up
All in all, it is important to make sure that you read the manuals of your Art-Net enabled devices as they are a little more complex than just setting up a few universes of DMX and running cable. By fully understanding the power and potential of Art-Net, setting up your system will be a walk in the park. To keep that walk in the park from turning into a run through the battlefield, bookmark your controller’s manual, the manual for the routers you are using, as well as the Artistic License website — artisticlicence.com. These guys know more about Art-Net than anyone else on the planet.
Michael Graham is product development manager for Chauvet Professional.
