DMX

From YSTV Documentation Wiki

DMX is a digital lighting control protocol, in which instead of 1 core for each channel used & a common gorund (like on the Lighting Desk), 512 channels of control are transmitted down 3 wires: Data+, Data-, Gnd, with ground usually being the sheild or braid, Data+ & Data- are a twisted pair.

Current supported devices

  • Chamsys MagicDMX dongle
  • Eurolite DPX405 dimmer
  • DMX outboard & Analogue to DMX system

Infrastructure

YSTV runs 2 lines (one each way)down a single Cat5e cable, from the control room's Master patch panel, to the LX patch panel in the studio.

Connections

These are on 3 or 5 pin XLR. Currently, all YSTV DMX equipment uses 3 pin XLR

DO NOT plug dmx into any sound gear or use audio cables as a substitute, something will get fried.

Technical

  • DMX requires a cable impedance of 120ohms.
    • So you must not use microphone cable!
  • Equipment is "daisy chained" together, using each device's input and an output ports(they must be the correct way round).
  • Data+ and Data- must be a twisted pair.
  • Multiple types of cable will do the job:


Sheilded Twisted pair:

  • This is the "defacto-standard"
  • You can get it almost anywhere, below are some retailers (no links because they inevitably die! - just go googling)
    • Canford
    • 10outoften
    • Usedlighting / stagelighting (lighting Partners Ltd)

Useful Notes

  • Don't run DMX right next to audio cables of any kind unless completely unavoidable, even if everything is balanced. You will hear the DMX data - The sync pulses manifest as an intermittent tone & noise.