What is DMX 512 for Lighting Explained
When you’re beginning with lighting, it’s not going to be long before you have questions about DMX.
In lighting, DMX is everywhere, and it is how our lights get information on what to do from our consoles or software.
Whether you’re 100% new to lighting or have been around the block, it’s super-important to have an understanding of DMX so that you can set your lights up correctly and troubleshoot any problems that come up.
DMX can be your best friend or your worst enemy.
When you follow the rules, your gear will work great and be a blessing to you.
On the other hand, if you don’t follow the rules, you’ll run into some serious headaches and trouble! Below, I cover the basic terms and information that you need to begin with DMX. Then, we dive deeper and show you how to do some deeper level wiring, splitting and converting. Let’s dive in!
DMX512 stands for digital multiplex 512. This means that 512 channels are controlled digitally through 1 data cable.
A channel is a set of 255 steps that are assigned to control attributes in each light. This may be a color like red, green or blue, and intensity, strobe, pan/tilt or other attributes.
This is pretty incredible if you remember some old analog control systems where you had 1 pair of wires for each channel of the console!
I don’t miss those one bit!
Data is sent down this line via pulses of electricity from a lighting console, into your fixtures that are usually “daisy-chained” together.
This means that you plug the initial DMX cable into the first fixture, the “OUT” of the first fixture into the second fixture, etc, up to 32 fixtures maximum – more on that below.
DMX is not manufacturer specific. DMX-controlled lights from any manufacturer can be controlled by any DMX console – even if that console is made by someone else. This is one of the biggest advantages of DMX and why it’s the standard that we use to control stage lighting today.
One of the first things you’ll have to do when you begin lighting is to address your fixtures.
An address is the location in the 512-channel universe that the DMX device begins. Often, this is referred to as the “start address” since it is the first address that a given fixture uses.
If you have a one-channel device, like a single-colored light that simply turns on and off, then you can address the fixtures one right after another. This would give you the first on address 1, the second on 2, etc.
Pretty simple.
However, if it is a multiple channel fixture, like an LED or moving light, you need to be sure and leave the total amount of channels the fixture takes open before patching the next fixture.
Not quite as simple!
So, if you have a 3-channel fixture starting at channel 28, the next open address would be address 31.
If you don’t do this, you’ll be trying to control one light, and another one may start doing something you did not expect!
While this might sound like you’re headed out to do a bunch of math – never fear! Your console or software likely will handle all the number-crunching for you in the “Patch” screen. Do this before you address your lights.
If you’ve been reading this article thus far, you’ve heard me mention Universes, but also maybe noticed that I haven’t told you how to assign them!
A universe of DMX is 512 channels of output from the console.
When you finish out the first universe of 512, you move over to the 2nd universe and restart at address 1.
Some consoles will continue the numbering scheme with the 2nd universe at 513-1024, while many will simply note each universe with a letter or number, and then the address – an example being “1.214” or “a.214” for a light on address 214 of the first universe.
On the back of your lighting console, you may see writing that says “Universe 1”, “Universe 2”, or “DMX A”, “DMX B”, etc. These are the DMX universe output ports.
Universes can’t be combined together, and each universe needs its own DMX cable run. When it comes down to your lights – they don’t know what a universe is, and quite frankly, they don’t care.
Each universe is “identical” looking to a light – it’s just happy to have DMX signal. That’s why it’s important to wire the correct universe up to your lights because they will not respond as you desire when they’re receiving the wrong universe!
In general, you begin at your console, and wire each fixture, looping through in a “daisy-chain”.
However, sometimes you need to split your signal or need to convert 3-pin to 5 pin DMX.
This is a biggie, and a big debate in the lighting community. While manufacturers and many professionals will tell you to never, ever use microphone cable for DMX lighting, it still does work, doesn’t it?
On this page, I get to the bottom of this debate, and why you need to use real DMX cable in your lighting, even if mic cable seems to work okay! This post is very important and will save you many headaches if you are considering using mic cable for DMX!
DMX is a great protocol to run our lights, but it can’t do everything.
One rule, which I mentioned above, is that you can’t have more than 32 devices on 1 DMX cable run.
What’s the deal with that?
As the DMX signal moves through your lights, it loses signal strength over time. At some point, it will become too weak to be reliable.
According to the specification, that is at 32 fixtures.
In real life, that number can vary from slightly lower than 32 to much higher, depending on a variety of factors.
I typically won’t go over 16 fixtures myself, just to be on the safe side. Remember: When lights are hung in a position that you require a ladder or lift to troubleshoot a data issue, play it safe and keep your numbers down!
While you can technically run DMX signal for 1800 feet, I’ve found that anything over 500 feet gets a little scary and can get flaky depending on the number of fixtures attached.
The good news is that if you do begin to have signal problems, you can always split and boost your signal to solve them!
If you have too many lights for a single daisy-chain, but haven’t filled up your universe yet, you can buy a DMX Splitter, also known as a DMX opto-split or DMX repeater.
This is the only way to split your DMX feed into more lines, and each output of the splitter can send data to 32 devices, allowing you to expand your capabilities.
If you try to do a passive split (a y-cable), then your DMX signal will get very weak very fast and you will have problems.
If a fixture has both 3-pin and 5-pin connectors, connecting to both on the output side is a passive split and will cause problems, but you can go into the fixture 3-pin and out 5-pin, or vice versa, which is a handy trick to save on adapter usage!
Another thing to note is that sometimes you may run into a piece of equipment that doesn’t play well with others.
Some cheaper fixtures can go into an automated mode when they lose data and send out funky data to other fixtures down the line. You certainly don’t want that in the middle of your show!
A DMX splitter will isolate those fixtures onto their own lines so that they don’t cause any problems with other fixtures. It’s a good tool to keep in your back pocket for emergencies!