Smart lighting systems used to be an expensive area for professionals only; but with the proliferation of cheaper electronics and computer control systems, incredible lighting effects are now within the reach of hobbyists. Whether you’re planning the coolest house party or want to take your Christmas or Halloween lighting to a whole new level, it might be time to invest in some DMX systems.
What is smart lighting?
Simply put, smart lighting contains elements that can be controlled remotely. At the most advanced level, this can include moving head (pan and tilt), patterns, and colors. At the simplest level, you can simply control the color (maybe a strip of RGB LEDs) or a dimmer. Simply put, smart lighting is cool.
Combined with a controller, you can send hundreds of devices at the same time, arranging them programmatically with a predefined display or working with effects live. It’s basically how I spent my nights at the university — sitting in front of the light board — moving, blinking and changing the color of the club or concert lighting in time to the music. At most concerts, the lighting will be pre-recorded and simply played back at the right time; it guarantees a consistent experience.
If you’ve seen the viral Halloween house lights video set to thriller, you should know that it uses DMX smart lighting control.
What is DMX?
DMX is a serial protocol, digital, unidirectional, no error checking. It is reliable but susceptible to interference, making it unsuitable for hazardous environments such as pyrotechnics (e.g., a stray signal or electrical interference can accidentally trigger a fire tower). Like most digital cables, signal quality degrades over long distances, and repeaters can be used to extend the distance or split the signal using equivalent Ethernet switches.
The cable itself consists of two shielded twisted pairs (although only one pair is used). You should technically use a 5-pin DMX cable, but some manufacturers have introduced 3-pin versions that can work over traditional XLR mic cables.
The devices are connected in series in one cable and connected with a special plug; one DMX master is used for control, and any other device is called a slave.
At the data level, DMX512 controllers send asynchronous data at a rate 250 kbaud ; 1 start bit, 8 data bits, 2 stop bits and no parity. Note that although some of the data is limited to 8 bits, some devices combine the two channels, giving a multiplexed 16 bit data packet if needed.
DMX512 is so named because it allows up to 512 control channels. Each device in the DMX «universe» must have a start address set on the device itself; most devices occupy more than one channel. Some of the more complex lights can have up to 12 different channels; the combination of which controls different effects. Identical devices can be installed with the same address; they will both respond to those instructions.