DMX512
Definition
DMX512 (Digital Multiplex) is the standard serial protocol for controlling stage lighting, defined by ANSI E1.11. It transmits data at 250 kbaud over an RS-485 (EIA-485) electrical interface. One universe carries 512 channels (slots), each taking a value from 0 to 255, refreshed at up to 44 complete frames per second. The standard sets no maximum cable length; ESTA recommends up to 300 m per line on compliant cable. The standard connector is the 5-pin XLR, and every line ends with a 120 Ω termination resistor.
In the field
Without a 120 Ω terminator at the end of a long line, the signal reflects back along the cable and fixtures flicker or move erratically, particularly those at the end of the chain. Technicians therefore usually carry a spare DMX terminator plug.
Related lessons
Sources
- ANSI E1.11-2008 (R2018) §3.34 : 512 slots de données par univers, le slot 0 étant le START Code
- ANSI E1.11 §8.1 : valeurs 0 à 255 sous START Code nul ; §7.1.1 : XLR 5 broches ; §4.9 : terminaison 120 Ω
- ANSI E1.11 tableau 6 : 250 kbit/s (245–255), 44 trames/s au maximum
- ANSI E1.11-2024 (remplace 2008 R2018, rétrocompatible) : EIA-485-A, 250 kbit/s · tsp.esta.org
- ESTA, Recommended Practice for DMX512 (2e éd.) : environ 300 m sur câble EIA-485 conforme, terminaison 120 Ω · tsp.esta.org