Automated lighting fixtures are extremely sophisticated, including movement of pan/tilt or other features. Fixtures and consoles provide a multitude of methods to ensure that these movements are either perfectly smooth or extremely quick… Once programmed into the console, the rate of changing DMX values becomes consistent during a programmed crossfade, and thus the fixture software can better anticipate the changes and move in a very smooth manner… Fixture designers also provide us with tools to change the behavior of the fixture and allow it to move differently. The most common method is to provide a DMX value to “turn off” the smoothing algorithm. Several manufacturers accomplish this by providing a “toggle” within the fixture’s movement timing channel. With a DMX value of 255, for example, the fixture will move smoothly, but not as fast as possible…There is yet another piece of the puzzle involved. Your lighting console will typically use a fixture library (or profile), which defines default values for each and every DMX parameter used by the fixture. If your console defaults the particular movement timing channel to DMX zero, then your fixtures are going to move quickly, but may not be smooth. On the other hand, if the console defaults your timing channel to DMX 255, then the fixture will move smoothly, but not as fast as physically possible. It is essential that you understand the timing channel options and how they are defaulted within your console’s fixture library
—From Brad Schiller, “Feeding the Machines,” PLSN, March 2013
