DMX512 brief description
By the time you are done reading this section, you will understand how DMX works and why the lighting world uses this standard communication protocol. For a more technical and detailed description, please visit www.dmx512-online.com
1. The need for a standard
About 20 years ago, most lighting and console manufacturers had their own proprietary communication protocols. During installations, it was necessary to use all lighting fixtures from the same manufacturer, of course with their own controller board. If you wanted to use lighting fixtures from different manufacturers (even simple dimmers), each group required their own lighting desk. It is clear that a standard form of communication between controllers and the fixtures was necessary.
2. Understanding DMX
To understand the DMX512 communication protocol (commonly referred to as “DMX”), we will use the “Cable TV” analogy.
Imagine a simplistic cable TV system, with only 4 relevant parts:
a. TV station
d. TV set
The TV station broadcasts a signal that travels through a cable network until it reaches a decoder. The decoder receives information on hundreds of channels, but only displays on the TV set the information (in this case video and audio) from that single channel that we select. The TV set ignores the information from any channel that is not selected. It only displays the information from the channel selected in the decoder.
DMX can be related to this cable TV system, where:
a. the TV station is the controller (Sunlite)
b. the cable is a DMX cable
c. the cable decoder is the DMX decoder (which usually is inside each lighting fixture)
d. the TV set is the lighting fixture
In DMX, the number of channels that are broadcasted is always 512. Maybe some of them will be empty or unused, but they are still broadcasted because it is a necessary component of the standard.
So, the controller sends out a signal (512 channels of information), which travels through a DMX cable until it reaches the decoder inside the lighting fixture. In the same way you set the channel you want to watch on your TV, in a lighting fixture you set the channel that you want your fixture to display the information for. This is known as the DMX address.
In other words, if I set my lighting fixture to channel 21, then my fixture’s DMX address is 21. Both expressions are common in the lighting world.
Imagine we have a DMX dimmer that controls a simple light bulb. This dimmer is set to DMX address 21, so the lighting fixture will only receive the information from channel 21 and ignore the rest.
We have a controller that sends a signal through a DMX cable and this cable goes into a decoder (the DMX dimmer) that receives the signal. So if the controller sends the “turn on” information on channel 21, the dimmer will turn on the light bulb.
Conventional lighting fixtures (simple dimmers) require 1 channel of information only. However, intelligent lighting fixtures require more than 1 channel to work. For example, if I have a lighting fixture that requires 5 channels of information, and its DMX address is 21 (again, address is the first channel used by the fixture), then this fixture will use channels 21, 22, 23, 24, 25. The decoder knows that the fixture needs 5 channels of information, so it will decode 5 channels only and ignore the rest. The controller knows the fixture uses 5 channels also, so it will send 5 channels of information.
Imagine you have a very simple robotic moving head that uses 5 channels:
3. color wheel
4. gobo wheel
You set your moving head to address 21 and you tell the controller that you have this particular moving head on address 21. The controller then knows that channel 23 corresponds to color wheel, for example. If you want to change the color of the light beam, you tell the controller what color you want, the controller automatically sends this information through channel 23, and the lighting fixture reacts accordingly.
Typically, intelligent lighting fixtures use 1 channel (sometimes more) for every function they can perform (color, gobo, prism, dimmer, etc). Some robotic moving heads use over 20 channels, some simple scanners only 4 channels, etc.
3. The protocol
So far, we’ve been referring to “information” traveling through DMX cables from the controller into the fixture’s decoder. This “information” is nothing but a number between 0 and 255. This number is called the DMX value for a particular channel. Then, the DMX signal is nothing but a series of DMX values along 512 DMX channels.
Back to our 5 channel simple robotic moving head; channel 3 controls the color wheel, which has 25 different color combinations. The color displayed will depend on the DMX value on channel 3 (as it is being sent by the controller) as follows:
241-255 “whatever color”
So, if the lighting fixture receives a DMX value of 25 for Channel 3, it will display the Purple color. If that DMX value changes to 15, it will automatically change to Red, and so on.
Luckily for us, the Sunlite software (and most controllers) includes profiles for these lighting fixtures. These profiles contain all the DMX values and channel information required to have full control of the lighting fixture. Typically, all you will need to do is set the DMX addresses right, and the controller will make everything else easy (some controllers are easier to use and learn than others, but that is the overall idea).
When a lighting fixture is manufactured, a DMX chart is provided in the user’s manual. This DMX chart contains all the information that controller manufacturers need to create these profiles. Most controllers include only the most popular fixtures in their particular market. We can proudly say that Sunlite (and our OEM partners) are the only controllers with over 2,000 different profiles from manufacturers from all around the world, so no matter where you purchased your lighting equipment, chances are we will have profiles for it, which will allow you to control them without a problem.
4. Sunlite Importance
Summarizing, most lighting fixtures and their controllers communicate using a protocol called DMX-512 (for a very detailed description of DMX history and technical specs, please visit www.dmx512-online.com).
Important about DMX and lighting fixtures:
1. Lighting fixtures use 1 separate channel to control every function they can perform (one channel to control colors, another for gobos, another for dimmer, another for shutter, etc)
2. You can use a maximum of 512 channels for every DMX line
3. There is a value from 0 to 255 assigned to every DMX channel
Important about Sunlite and lighting fixtures:
1. When you tell your Sunlite controller what kind of lighting fixtures you are using, Sunlite will know exactly how your fixtures work and what DMX distribution they have.
2. This allows Sunlite to show preprogrammed buttons on the screen corresponding to every function that the lighting fixture can perform (1 button for white color, a different button for red, 1 button for every gobo, for every macro, etc).
3. To begin programming lighting effects using Sunlite, all you need to do is click on preprogrammed buttons!
4. Because of its visual interface and simplicity to program, thousands of users worldwide have chosen Sunlite as their preferred lighting controller