This blog post is going to be talking all about DMX512 for lighting equipment. What is it, what does it do, how does it work, and is it something that you can use in your lighting design. If you’re currently working on a studio lighting design and you’re wondering if DMX is a feature that you need in your lighting fixtures, this is the right article for you.
DMX: What is it?
Simply stated, DMX512 is a standardized protocol for controlling lighting equipment. The letters DMX stand for “Digital Multiplexing” or just “muxing” and the “512” refers to the number of separate “channels” of information that can be sent simultaneously.
Digital Multiplexing is a complicated sounding term that just means sending multiple streams of communication data over the same physical medium (e.g. cable) at the same time. A good example of this would be physical phone lines. They carry multiple data connections over the same cable simultaneously. There are many, many methods of how this is accomplished that have been developed over the years which you can read all about here.
In this article, we’ll boil the “what is DMX512” question down to this: It’s a way for a controller to send multiple signals to multiple lights that can do many different things, all at the same time.
DMX: What can it do?
DMX512 ranges from very simple control to very complex control, and it’s all based on the previous section with multiple data streams running at the same time. Lights with DMX capability assign functions to “channels”. For example, you might have a light that has just one single DMX controlled channel for dimming. That means that you can plug a DMX control board into that light and, using a slider on the control board, make the light brighter or dimmer by moving the slider up and down.
The complexity of what DMX can control just expands from there. Each different variable to be controlled is simply assigned another channel on the DMX board. RGB lights with red, green, and blue LEDs might have three channels for dimming. This way, you can control the mix of red, green, and blue from the DMX board and effectively control the color output of the light fixture. That same RGB light might add a fourth channel for “master dimmer” so that all of the LEDs can be controlled by a single fader. It might add a fifth channel for a special effect like “color chasing” or “strobe flashing”. Each new variable just adds another channel to the light, and with 512 channels available, there is plenty of space to get creative!
You may have seen lights that rotate, pan, tilt, and flash. All of these functions can be controlled via DMX. There are lighting fixtures that have 40 or more channels controlling things like movement, color, special effects like strobe, pulsing, color chasing, and other variables. DMX512 is also used in other non-lighting equipment like fog machines. There really are few limitations to what DMX512 signal can control, and most of those limitations are imposed as a matter of safety (think pyrotechnics, etc.)
Some DMX lighting designs get so complex, with so many lighting fixtures and channels that even 512 isn’t enough! This is where a concept called a “DMX Universe” comes into play. DMX512 is limited to 512 channels (more on that in the next section), and some DMX control boards allow the user to create multiple universes to accommodate the need for more channels. If you’re using lights that have 30 or 40 channels, it won’t be long until you run out of room in a DMX512 universe. Multiple universes allow for essentially an unlimited number of DMX channels to be controlled from one control board.
DMX: How does it work?
One question that gets asked a lot is “Why 512 channels? That seems like a random number.” Well, the answer has to do with binary. DMX512 protocol was set up was with binary “on/off” switches. In order to set up lights to use with a DMX board, you have to give each light a starting “address”. This means that you tell the light which DMX control channel it assigns its first channel to. So if you have a light that has two channels (e.g. dim / color), and you set the starting address to “1”, then that light will be controlled on channel 1 and 2 on the DMX control board. If you set the starting address to “2”, then the light will be controlled on channel 2 and 3 on the DMX board and so on.
These days, lighting fixtures have digital control menus to set options like DMX starting addresses. But before lighting equipment had these features, we used something called a “dimmer pack”. A dimmer pack was a like a power strip with physical switches on it to set the DMX starting address. It didn’t make sense to try to put 512 physical switches on the dimmer pack, so they used 9 switches and binary instead.
How does this work? The 9 switches were numbered exponentially like this:
1, 2, 4, 8, 16, 32, 64, 128, and 256
By setting these dipswitches to the on or off positions, you could arrive at any number between 1 and 512. For example, to set the starting address to “3” you would turn on switch 1 and 2 and leave the rest off. To set the starting address to “13” you would turn on switch 1, 3, and 4 and turn the rest off.
This is a very basic explanation, and you can read much more in depth here, but once each light is assigned a starting address, and plugged into the DMX board, that light can be controlled remotely. Not only that, but multiple lights can be assigned to the same starting address, so that one fader can control multiple lights on the same DMX channel. This works great if you want to control a whole group of lights quickly. It can also backfire if you’re not careful setting up your DMX channel map. Since channels can overlap, you can end up with multi-channel lights having their starting addresses too close together and accidentally control multiple things at the same time without meaning to.
Are there alternatives to DMX512 for lighting equipment?
DMX512 was standardized almost 40 years ago, so it’s been around a while. It remains the standard, but technology has allowed for new things to be done with DMX512 protocol as well as completely new alternatives.
One of the biggest pain points with DMX is the cabling. All of the lights in a DMX lighting setup need to be connected with cables. The nice part is that since DMX is only for communication signal and not power, those cables can be “daisy chained” so that each light can plug into the one before it instead of all lights plugging into the DMX board itself. This is why you’ll see lighting fixtures with a DMX “In” port and “Out” port.
Even then, setting up DMX cabling takes time, and it’s not always easy, so a lot of recent technology advancements have aimed to eliminate the need for cabling to create wireless DMX. The problem with this is in standardization and proprietary technology. There are several wireless data standards that exist today that you can read about here. Everything from Bluetooth to Wi-Fi, to Lumen Radio are being used to eliminate the need to run long DMX data cables, and soon, we may see DMX get replaced by one of these standards. The Dracast X-Series and Palette Series for example use their own apps along with bluetooth as a remote control option.
Do I need DMX?
Customers ask this question a lot. Luckily it’s a pretty easy one to answer by answering these questions:
- Will your lights be permanently installed and out of reach?
- Will you need to control your lighting from one location?
- Will you need to control multiple lights all at the same time?
If you answered yes to these questions, then DMX might be a suitable option for you. Dracast and Cinebrite lights both have models that include DMX capability. If you’re considering DMX lighting for your installation, contact the product support team at Draco Broadcast at 856-324-2892 or by chatting with one of us right here on this page. We’re always ready to help.
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