In order to fully understand the purpose of patching, you must have a notion of the basics for DMX communication. The automated lighting console outputs 512 distinctive DMX channels per universe of DMX. Each of these channels is capable of 256 unique values between 0 and 255. A DMX-controlled lighting fixture will respond to a pre-assigned number of DMX channels and relate their values to the various parameters of the fixture. For example, a simple fixture might use seven DMX channels to control all its functions, with one channel controlling each parameter (pan, tilt, cyan, magenta, yellow, zoom and dimmer). This mapping is known as the fixture’s DMX protocol. The specific DMX values of each channel relate directly to the associated mechanical function. So a DMX value of 0 on the seventh channel will cause no light output, while a value of 255 will result in full light output.
– From Brad Schiller’s Feeding the Machines column in the February issue of PLSN
