DMX Lighting Protocol

This is the first technical piece in our series. Up until now the posts have been more design focused while this will cover the technical aspect of the protocol used to connect every light seen on a modern stage. DMX512, or as will be called from here on out DMX, is the main protocol that connects lights and sometimes other features on a stage. DMX was created in 1986 by the United States Institute for Theatre Technology (USITT) as a standardized method of connecting lighting consoles to dimmers and was revised in 1990 to what we know today to allow more flexibility. DMX is most commonly found today as a five pin XLR connector called XLR-5. The first pin is ground, the second two are data, and the last two are optional data pins. Because the last two are optional, DMX can also be found as a standard 3 pin XLR connector. The data that goes through this connection is asynchronous serial data at 250 kbit/s. Each packet of data also includes a start code which signifies what kind of data is being sent so devices can understand how to act on the data that is being sent to them. An important part of this data is that it has no parity bit, meaning that all DMX data that is sent has no error checking and any device receiving this data must accept and act on it all at face value even if it has been corrupted. Therefore, it is advised to not control large motors or pyrotechnics over this protocol. DMX allows for one controller to connect to many fixtures through daisy chaining them together. Each device will have a DMX in and a DMX out to allow the continued connection. At max capacity, one controller could talk to up to 512 different devices through the channel system. Lights are connected one or more of the 512 channels that gets controlled through the protocol. A dimmer may just need one channel because it just has one feature, its brightness while an RGB light may have 4 channels: 3 for each color and one for brightness. This protocol is very expandable to allow basically anything someone could imagine. This and the fact of the robustness of the cable has created the popularity for this lighting control protocol.