What is DMX 512?

By David / a couple of months ago

What is DMX512?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 lighting equipment gives and gets instruction on what to do and when.

Whether you’re 100% new to lighting or have been around the block, it’s super-important to have an understanding of DMX and what to do/what not to do.

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!

What is DMX 512?

From Steadiness. on Flickr.

DMX512 stands for digital multiplex 512.  This means that 512 channels are controlled digitally through 1 data cable.

A channel is 1 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.

What is an address?

DMX lightingOne 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 conventional channel on a dimmer, than 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!

The good news is this – today, Most moving light and PC-based consoles will work out the channel patching for you, but some basic conventional consoles do not!

What is a Universe?

DMX stage lightingOn the back of your lighting console, you may see writing that says “Universe 1”, “Universe 2”, or “DMX A”, “DMX B”, etc, but what in the world is that?

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, however, will default to numbering the 2nd universe at channel 513-1024.

Universes can’t be combined together, and each universe needs its own DMX cable run.

Many simple lighting consoles only have 1 universe, so if you are just starting out, you probably don’t need a great understanding of DMX 512 universes.

How Do I Wire DMX?

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.   Get all the details and a video explanation on this page!

Can I Use Mic Cable for DMX Lighting?

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!

What are the limitations of DMX 512?

DMX is a great protocol to run our lights, but it can’t do everything.

One rule is that you can’t have more than 32 devices on 1 DMX cable run.

However, this isn’t a hard and fast rule, as different DMX devices have different electrical resistances, so that number may be slightly higher or lower.  Be sure to play it safe, as you don’t want to have a data issue and lose control of some or all of your lights.

I typically won’t go over 16 fixtures myself, 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!

So how can you save devices or split signal?

If you have a lot of LED fixtures or moving lights, but haven’t filled up your universe and want to add more- you can buy a DMX Splitter, also known as an opto-splitter or DMX repeater(Here’s my review of my favorite low-cost DMX splitter)

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 also 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!

An opto-splitter can 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!

Learn more about splitting, merging and converting DMX signal here!

Got DMX Problems?

One of the top reasons that people land on this page is because they are facing a DMX problem.

DMX problems can manifest themselves in a few ways.  It may be that your lights aren’t working at all, or perhaps they’re not doing the correct thing!

Either way, read this page which will help you get to the bottom of your problems and get you on your way to a great show!

What about RDM, Art-Net and sACN?

Art-Net and sACN

Learn more about Art-Net and sACN here!

These days, you don’t have to hang around lighting people for long before hearing these terms, but what do they mean?

RDM stands for remote device management and is a cool way to change “menu settings” on your lights from afar.  Learn more about RDM with my complete guide here!

While we’re not totally to the “self-addressing rig” yet, we’re getting there, and that’s exciting!

Art-Net and sACN, on the other hand, are ways to send your DMX data over a network.  Both have their pluses and minuses, and I’ve prepared a complete guide over here!

Whether you’re just beginning with DMX, or wanting to dive deeper, I’m glad you’ve found this article.  Be sure to poke around this site, and sign up for the free guide that I have for you below, and keep learning about light!

Like Our Free Content?

Click Here

For the Very Best Learn Stage Lighting Has to Offer​....


Leave a comment: