DMX lets you control pretty much every aspect of a given fixture, dependent on the number of channels of control a given fixture has. So for a scanner; color, gobo, x & y axis, speed, and sometimes intensity can all be controlled by you. Or with the right controller, programmed by you to run a specific sequence. On a LED par you can control the amount of red, green and blue to create theoretically any color. With a RevoIII or VueIII you can set it to only run that "fireworks" effect that everybody loves. My basic set up includes two LED barrel scanners, which I usually run on sound mode. However for certain slow songs, I switch it to a white dot pattern, set it to spin level across the room, adjust the speed, and presto...instant mirror ball effect.
Most controllers use sliders to control each channel. On my barrel scanner one slider is for direction and speed of spin, one for pan control, one for flash/blackout, and one for pattern/chase which can also set it to sound mode. The two scanners are linked to mirror each other.