Generally, the only time I’ve ever seen DMX in use is for stage productions. [Dan] sent in his home light control project – he used a RS-232 to DMX interface and a bunch of commercial DMX dimmers. His light switches were replaced with potentiometers connected to the system via CAT5 cabling. The POTs send 0-10v up the line to the dimmers, and the manual control can override the automated(DMX) settings. The system is simple, robust and responsive – avoiding the delay pitfalls usually incurred by systems like X10.