If you’ve worked with lights, you know the basics of controlling them with DMX. Just move a slider on the lighting console, and the console sends a DMX signal to the corresponding piece of equipment – telling a fixture to dim, a scroller to change to red, a moving light to pan left.

But it’s a one-way conversation. The person operating the console talks, and the equipment listens. The lighting tech gives the orders and the device obeys – or, at least, it should. That’s the hope, and that’s how it’s worked for years.

Just because it has always been that way doesn’t mean it’s the best way.
The days of the one-way conversation are over. Today’s equipment doesn’t just listen: It talks back.

Just as DMX serves as the “language” that lets humans talk to light fixtures, new languages developed by lighting experts now enable the fixtures to talk to the people controlling them. Not so they’ll rebel – but so they’ll send feedback to the humans to make their jobs easier.

And just like DMX, these feedback languages can be used by any brand of lighting equipment. That’s why they’re called industry standards.
The concept of feedback as it relates to lighting equipment may seem a little abstract, so let’s take a look at some practical ways we use feedback every day.

A CAR WITH NO DASHBOARD?
Consider the vehicle you drive. How do you know when you’re about to run out of gas? Your fuel gauge tells you – or else your car sputters and dies on the side of the road. How do you know when something’s really wrong with the engine? Look for the “check engine light” – or wait for smoke to billow out from under the hood. How do you know when you’re speeding? Check your speedometer – or look for the flashing red and blue lights behind you.

Another feedback example: Your computer printer. When you run out of ink, it’s a massive pain, especially if you’re trying to print something you need right away. But today’s printers let you monitor your ink levels from your computer screen, showing you when you’re getting low on ink – and giving you time to buy an extra cartridge before the current one goes bone-dry.

Of course, you could drive without a fuel gauge or a check engine light or a speedometer. And you could use a printer without monitoring the levels of its ink cartridges.

But why do that when feedback makes things so much easier?

LET YOUR COMPUTER DO THE WORK
Let’s look at how feedback can benefit your lighting rig.

• Troubleshoot Problems
Pretend there’s a problem with one of your lights. Normally, to find out exactly what’s wrong, you’d need to climb up to the fixture and physically inspect it. But with a feedback system, you can stay firmly on the ground and use your computer to tell you what’s wrong. Is it a burnt-out bulb? A blown dimmer? Feedback can tell you.
• Track Maintenance
Don’t have time – or enough staff – to keep detailed records of every single piece of equipment in your rig? Let a feedback system do it for you. As sensors on the equipment record information – how long a bulb has been in a fixture, how long a gelstring has been in use – they send it back to the system, which compiles it for future reference.
• Smooth the Setup Process
To control the equipment on a lighting rig, first you’ve got to assign a DMX channel to each device. That typically means handling each one – light fixtures, dimmers, scrollers, and countless others – and setting the DMX address for each one. With a feedback system, you don’t need to spend time with each individual device. The feedback system will scan your entire rig and let you assign DMX addresses to all your devices from your computer.

With the benefits of feedback clear, lighting pros needed to develop the languages that would let equipment talk back to their operators. But it had to be an industry-standard language that every manufacturer could speak.

CREATING A COMMON LANGUAGE
Without a standard language such as DMX – or “protocol,” as it’s called in the lighting world – different brands of lighting equipment wouldn’t be able to work together. A Martin moving head couldn’t be controlled by a grandMA console, for example.

That’s why lighting pros developed DMX512 – an industry-standard communication protocol that lets lighting devices made by different manufacturers work together.

To enable these pieces of equipment to send feedback to their operators, lighting pros needed to develop another protocol, this one allowing two-way communication. And, like DMX, it needed to be an industry standard so that all manufacturers could use it.

For the lighting industry, the organization that develops these protocols is the Entertainment Services and Technology Association. Based in New York City, the nonprofit ESTA ( www.esta.org ) represents production companies and individuals across North America.

Developing a new protocol is a complicated, lengthy process. First, ESTA’s Technical Standards Committee sets up a working group tasked with developing the protocol. These working groups can include people from a wide variety of backgrounds, from the people who manufacture lighting products to the customers who use them.

This group hammers out a document, then makes it available for public review. After the group considers any input and makes any revisions, then ESTA’s board of directors votes on the final product.

So far ESTA has approved two feedback protocols. In the next section we’ll look at both of them.

RDM AND ACN: THE FUTURE OF FEEDBACK
Only one feedback protocol has been fully approved by ESTA: Remote Device Management, or RDM. A second feedback protocol has received partial approval from ESTA – Architecture for Control Networks, or ACN.

At first glance it might look like having two feedback protocols could be confusing, but the two actually complement each other. ACN excels in signal distribution, especially in large, complex lighting rigs. Using ACN, a control signal can be routed around a building similar to the way data gets routed around the Internet. This lets operators use a large number of devices and even multiple lighting consoles at the same time.

But ACN can’t talk directly to today’s lighting equipment, which is controlled by DMX. And that’s where RDM comes into its own: The RDM signal is transmitted over DMX cable, making it easy to use with most lighting rigs.

THE FIRST FEEDBACK SYSTEM
Wybron, a veteran lighting company based in Colorado, jumped into the feedback world in 2006 with its Infotrace Control and Management System. Infotrace uses RDM to gather feedback from lighting equipment and sends that feedback to the user’s computer.

So customers could get the most feedback possible, Wybron installed numerous sensors into most of its products. For example, sensors on the company’s Eclipse IT mechanical dowsers register temperature, voltage, and more.
But in the lighting industry, no man – or manufacturer – is an island.

JOINING FORCES: MANUFACTURERS WORKING TOGETHER
In 2007, Wybron met with Wisconsin-based ETC and suggested the two join forces to create an ACN-RDM bridge. They soon started working on feedback products that would work together, allowing a true marriage of the two protocols.

At LDI 2008 in Las Vegas, Wybron and ETC both demonstrated working prototypes of the “holy grail” of feedback systems: An ETC Ion lighting console sitting beside a Wybron Infogate interface, both operating together with true feedback.

And this setup at the Wybron booth also connected to fixtures from other manufacturers, including Martin and Robe, both lighting giants based in Europe.

The list of manufacturers using feedback protocols grows longer every day – High End Systems, Leprecon, City Theatrical, Altman, and more.
But what does the future hold for this emerging technology?

THE FUTURE OF FEEDBACK
They say necessity is the mother of invention. And to accommodate the demands of today’s audiences, lighting systems are becoming increasingly more complicated, especially in houses of worship. Automated fixtures, performer-tracking systems, digital projection, and LED technology have truly pushed the worship experience into the 21st century.

But along with this complexity comes the difficult responsibility of being able to configure and troubleshoot the entire lighting system. And that’s why having a feedback system is fast becoming a necessity, not just convenience.
With more complex equipment, more complex installations, and, in some instances, less experienced or volunteer staff, it’s vital for the lighting rig itself to proactively tell staff members about the health of the lighting system. Feedback makes that easy.

The move to feedback-enabled lighting systems marches on. The next time you buy equipment, ask your lighting dealer for products that will talk back to you.