DMX 512

The DMX 512 is a protocol based on RS-485 that is used to control both theatrical stage lighting and effects. The DMX 512 was developed in 1986 and revised in 1990. It is a standard developed by the Engineering Commission of USITT. Today the standard is also known as E1.11 or DMX 512-A.

The DMX 512 is a common method for linking controllers and dimmers. It can also control more advanced items such as fixtures, fog machines and moving lights. It should be noted that DMX 512 should not be used for applications involving pyrotechnics or other situations when high levels of human safety must be maintained.

Devices or fixtures are connected to the DMX 512 in a daisy chain configuration. Most devices created for theatrical lighting or effects include a DMX 512 input and output. Because it is a daisy chain configuration, the DMX 512 connects into the first device’s input and then a cable from that first device leaves the output of the device into the next device’s input being used. This is continued until all devices are connected. It should be noted that the final device connected to the daisy chain has a terminating plug attached into it. This plug is essentially a resistor. It should be noted that due to the design of the DMX 512 standard and its technical specs, the DMX 512 can handle 32 units in a load. Each unit can include many fixtures, making the DMX 512 an extremely useful standard to use no matter what the number of fixtures or devices attached.

Connectors that are used by the devices that hook into the DMX 512 daisy chain must be five-pin XLR. Only 3 pins are used in operation, but the technical specs always require a 5 pin connection. Some cables come in 3 pins, but they are in essence prohibited and in violation of the standard.

There are two standards that are used for the DMX 512 cable. They include one standard for portable cables and one for permanent installations. Cables used with the DMX 512 must meet specific impedance and capacitance levels. Other types of cables such as microphone cables should never be used with DMX 512.

The DMX 512 has plenty of advantages including the ability to control a wide variety of devices and fixtures, the fact that is quite affordable and that the standard is quite powerful giving a lot of control to lighting and device designers. This has made it very popular in the entertainment industry.