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July 2004
Networked Lighting Systems
The Future of Control
By Stephen Ellison
When I started in lighting back in junior high school, the dimming system did not have a separate control panel, the handle you moved was mechanically attached to the dimmer- an autotransformer.
Even in my first year in college, the 48 dimmer system was still an autotransformer system with mechanically linked handles so that all 48 dimmers could be controlled by 2 large handles. A bump to black required a large football player, not someone like me, at all of 120 lbs.; I was good for about a 5 count fade when I hung on the handles.
As the years have gone by I have watched the control systems change as the electronics industry revolutionizes the world. The first jump was from the autotransformer to electronic switches. Instead of having your mechanical control directly at the dimmer, you could now move the console out into the house to see what was happening from the audience viewpoint. The electronic switch allows us to control large amperage that requires a big wire, with very small amperage running over a very small wire. Also, dangerous 120 volt current stayed with the big wire, while the small wires only used low voltage (24 volts or less).
These early consoles were still limited to a handle per dimmer, so they could get very large, and you needed one wire per dimmer. Moving the console around in fixed installations was not possible. Eventually smaller portable packs became available, but the control cables were still thick and bulky, and limited to a fixed number of dimmers. Interconnectivity between manufacturers' consoles and dimmers was not possible.
The next big leap came with the introduction of the microprocessor. Now we jump from analog control, (one wire per dimmer) to digital control. Digital control brings a host of changes into the picture. In the beginning, each manufacturer wrote software to talk between their console and dimmers. The industry was still small and there wasn't any standardization. The microprocessor was so new, all the possibilities had yet to be discovered. It was a free-for-all trying to develop the best console with the most features. What this produced was a myriad of languages that the consoles spoke, and of course, every one of them was exclusive to their own dimmers. After a while the industry shook out all the little guys and only a few of the big players were left.
The user side of the industry wanted interoperability, ie: one console talking to different dimmer packs. I remember as a rental manger you needed to be able to send out any console with any dimmer pack or group of packs to fill the customer's needs.
Thus another industry was born, the black box, or translator device that would take in one language and spit out another. Thankfully by the late 1980's the industry had convinced the manufactures that a standard needed to be set for a single language. Out of this desire was born DMX512. This language allows for the transmission of the data for 512 channels of information. Back then, the language was designed to speak to only 512 dimmers, and that was a huge amount. The really fancy consoles for Broadway and Las Vegas were designed to output 3 universes of DMX, which works out to 1536 dimmers.
During this time, dimmers were still expensive. Systems were designed with a relatively small number of dimmers, and included a physical patch bay. The patch bay, where you plugged the circuits, was the place where the fixture was plugged in, into a dimmer. The dimmer would have anywhere from four to six female holes so that you could gang fixtures together into one dimmer. The future has become one dimmer per circuit, and the patch bay is gone. Today it is not unusual to install 192 to 288 dimmers in a large church. That still fits easily into the 512 available in DMX, so why would we need anything else?
As I said, DMX was designed to only speak to dimmers, but the microprocessor did not just revolutionize the consoles, but also the fixtures. Even before DMX was developed, a little company in Texas, Varilite, produced a moving light and console. This was the start of what has become a very large industry.
20 years after the start of moving lights, I was working on a show that had 350 moving lights and required 8 universes of DMX. They were back to needing 8 cables going from the console to the backstage area, a bundle to match the old analog days.
DMX had turned out to be a good enough standard to allow the consoles to talk to a whole host of devices that are not dimmers, such as moving lights, color scrollers, strobe lights, fog machines, and others.
Now those 512 channels can be taken up quickly, as a simple moving light is around 10 channels. DMX also allows for communication in only one direction; a problem can only be detected when the lights don't change the way you expected. With all these other devices, the console setup is getting even more complicated. You have to remember to set the device to the right channel, or you can get some interesting results.
From the looks of it, DMX needs some help, in just a few short years we have already reached its limitations. Yet there are those out there that want more. They want to plug in a new device and have the console and the device talk to each other; and how about reducing the cable size again so that we only need one cable?
Some of these features are available now through networking. Just as our industry has grown exponentially, so has the computer industry. Only seventeen years ago I graduated from a two floppy drive computer to an XT with a 40 megabyte hard drive. Back then, I thought it would take years to fill that baby up with data. Now my computer has 512 megabytes just in RAM, and the hard drive is 60 gigabytes. When I bought the computer, they were offering a wireless router for free with the purchase.
Networking is a very big business which we depend on every day to run seamlessly. The lighting industry has already made the leap into networking, actually a number of years ago.
They made that leap the same way they joined the digital age, with proprietary networks, designed by manufacturers. Right now there are at least four different network systems. Guess what? They don't talk to each other. Now you can send 64 universes of DMX data over one Cat5 cable, which equals 32,768 channels. You can attach a device anywhere on a network that will provide two DMX ports which can either be inputs or outputs. The ability to move the data around your church is easier then ever.
Let us look to the future, where we all want interoperability, and all the manufacturers play together. ESTA, (Entertainment Services & Technology Association) is the industry group that oversees new standards in the theatre world. <www.esta.org> They are currently working on a standard for Remote Device Management over DMX, and the big one, Advanced Control Network. ACN will provide a standard for all the manufacturers to operate under. These standards are currently going through a long process of draft and review which will take several years to adopt. All of them are currently written and out for public review, you can keep tabs on ESTA's website.
All of these new control protocols were demonstrated last November at the Entertainment Technology show. <www.ldishow.com> These protocols will serve a variety of gear from various manufactures, so the future seems very bright.
Soon we will see a new future of control to go with all of the other changes to the lighting industry. The changes I've already seen in 35 years, range from autotransformer dimmers to the ability to control 32,768 channels with the push of a button. All these changes are amazing, and I believe we haven't seen the last of them. In the next issue we'll learn about the future of fixtures and video.
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