DMX Lighting Control
DMX512 (DMX) is a unidirectional protocol. Devices are linked in a multi-drop bus topology commonly referred to as a daisy chain. Each device has a DMX512 IN and DMX512 OUT (sometimes referred as DMX512 Thru). Communication conforms to EIA-485 voltage levels and cable practices so theoretically a run of 1200 metres is possible but practical limitation prevent this ideal. The end device in the run will need to be terminated with a passive resistive load to prevent signal reflections.
Commonly used in architectural or external scenic lighting, the control of Red Green and Blue DMX drivers to create the lighting effect is limited to 512 channels per run. With the use of a KNX-DMX controller, scenes, statuses and scheduling of light displays over multiple runs can be automated and easily updated.
DMX is a simple and robust technology which fits well with simple predefined lighting scenes. Integrated with a KNX-DMX sequencer the flexibility of this technology is greatly enhanced creating interactive, environmental responsive, complex lighting scenes.
Reference:-
http://en.wikipedia.org/wiki/DMX512-A
http://en.wikipedia.org/wiki/DMX_(lighting)