Re: Onward, upward.
Hi Steve. The other guys have given good info. One small correction to your post would be that generally channels describe absolute values, rather than movement commands. Your post said "one for left rotation, one for right rotation". That's generally not how they work. Rather, one channel would describe the absolute position in the potential axis of movement. For example: for pan, the 256 steps of that DMX channel would be mapped around the 540 degrees of rotation (or whatever range your fixture has) - meaning every time I send the command "146" on the pan channel, the light would move to whatever position 146 corresponded to.
Most lights use a "coarse" channel and a "fine" channel for things like position, which then gives 65000 potential positions across the range of motion, rather than just the 256 possible steps with one channel.
As Tim said, using real DMX cable is good, and usually a terminator is required at the end of the line. Depending on cable length, there is a limit to the number of devices you can chain before the signal gets too degraded to use. I can tell you from experience this past weekend that 700' of DMX cable and 20 devices was too much - I had to split my line by using a second "universe" (another output with a unique set of 512 more DMX channels). Optionally, I could also have used a DMX splitter
http://www.dfd.com/splitters.html which regenerates the signal and provides multiple outputs.
Understanding the DMX protocol is really simple - 512 channels per universe, 256 values (0-255) per channel. Understanding how to control complicated fixtures and program them to do useful things in reasonable amounts of time is much less simple. Getting a good controller makes all the difference here.
At the low end, some reasonable controllers are:
Elation Show Designer 1 and 2
various computer software
In the medium end, the ETC SmartFade ML is good, or Chamsys MagicQ software (lots of functionality, close to free)
At the high end are the Hogs, the Jands Vista, and a few others.
I'm not much of a lighting guy. I came from standard dimmers and theatrical style boards. I made the jump to LED wash fixtures, and very quickly outgrew a theatrical style board. After a couple gigs, I'm just starting to find my way around my SmartFade ML, and am getting pretty excited about what it can do.
