“Oh no, it wasn’t the airplanes. It was beauty killed the beast.” — Robert Armstrong as
Carl Denham in the original King Kong (1933).
There’s a new movie in the making that will soon be playing in theatres and performing arts spaces everywhere. It’s about a new protocol that goes up against a monster bundle of cable. The winners in this battle are the techies and end users of large lighting systems.
The movie is actually a sequel. The original version came out in 1986 when 0-10V analog control was getting out of hand. Lighting systems went from tens of dimmers to hundreds of channels of control, not only for dimming, but also for automated lighting. What once was a very manageable bundle of cable because a huge ugly beast that terrorized roadies and techies everywhere. Along came DMX and suddenly there was a new hero who conquered the analog cable bundle beast. In its place was a single twisted pair that could control up to 512 channels — enough for even the larger lighting systems of the day.
But as we all know, in the movies, even when the evil villain dies that’s no guarantee they’re gone forever. And that’s why we have sequels.
In this case, the monster cable bundle started rearing its ugly head again in the late 1990s when lighting systems reached epic proportions. But the thing went positively steroidal after 1998 when the monster’s sidekicks, the DMX-controlled media server and the RGB LED luminaire, entered the stage. Suddenly we went from hundreds of control channels to thousands of control channels. The single twisted pair was overthrown by a massive bundle of DMX universes and the monster cable bundle was back in power.
Fortunately for us, the smart people in the Controls Protocol Working Group of ESTA saw the proverbial writing on the LED wall. The cavalry mounted and rode to meet the monster head on. Several years into the battle, ACN was born and the industry had a standard by which many DMX512 universes could be transmitted over a single cable. They had slain the cable monster once again. Or had they?
In an unexpected plot twist, manufacturers stayed on the sidelines in droves while the ACN train pulled out of the station. While it’s too early to say that few of them are on board with ACN, it’s not too early to say there’s not a lot of evidence to the contrary (other than ETC’s Eos console, which outputs ACN). Meanwhile, several third parties built their own platforms to slay their own cable monsters by streaming DMX over Ethernet with a proprietary protocol. Some of these solutions including Artistic Licence’s ArtNet, Pathway Connectivity’s Pathport, ETC’s Net2, Strand’s ShowNet and probably a few more.
So, while there are plenty of white knights ready to slay cable monsters everywhere, there is no single solution that plays well with all systems. If you were on a big job with lots of nodes, it would be much easier if you could mix and match across manufacturers. With proprietary protocols, that’s not an option.
But the folks at ESTA aren’t satisfied to sit on the sidelines and watch the parade go by. Instead, they re-mounted their trusty steeds and they are now working on a standard to stream DMX over ACN.
The draft version of BSR E1.31 — Lightweight streaming protocol for transport of DMX512 over ACN is out for public review, and it promises to slay the monster cable bundle once and for all (or at least until the next sequel — Streaming DMX512 Versus ACN: The Cable Monster’s Revenge). As the title says, this protocol will allow the transmission of DMX512 data over an Ethernet network using part of the ACN suite of protocols. It can also send and receive RDM data as well.
The advantage of streaming DMX512 over Ethernet is that an Ethernet network is a much bigger pipe than a DMX512 network. Ethernet can handle dozens and dozens of DMX512 universes across a single cable, which is how the monster cable bundle is finally put to rest. You’ve heard of Cat5 cable, no doubt. A Cat5 cable can support data rates of 100 megabits per second, which can reliably run up to 200 DMX512 universes, or 1,000 megabits per second, which can run up to 2,000 DMX512 universes. Cat5e cable is a better choice for 1,000BASE-T, or “gigabit” Ethernet, which is what we call Ethernet running at 1,000 megabits per second.
The disadvantage is that Ethernet networks can only be run a maximum of about 300 feet before they run out of gas. Ethernet also has a star topology, meaning that a cable has to be run to each device, negating the advantage of slaying the monster cable bundle.
The best of both worlds is to use a combination of DMX512 and Ethernet infrastructure. We start by using an Ethernet network over which we stream DMX512, but then we change it back to DMX512 before we distribute it to all the devices on the network. This allows us to take advantage of off-the-shelf hardware like routers, switches, hubs and Wi-Fi, but we still get the advantages of DMX512, the biggest of which is probably the fact that there are millions and millions of dollars worth of DMX512-compatible gear already in use every day. We don’t have to trash our gear to take advantage of the new technology, as was largely the case in the original movie when DMX512 supplanted analog control.
For these reasons, DMX512 will probably be around for a long, long time while the monster cable beast might rest in peace for as far into the future as our crystal ball will allow us to see. Is streaming DMX512 over Ethernet for everybody? Not necessarily. But for applications where there are multiple universes of DMX512, like the Opening
Ceremony of the Games of the XXIX
Olympiad in Beijing where over 2,300 DMX512-controlled devices used more than 45,000 parameters — the equivalent of 88 DMX512 universes — it’s a an Oscar-winning technology.
What does a bundle of 88 DMX512 cables look like? Thanks to Ethernet, we may never know.
