DMX: Difference between revisions
From YSTV Documentation Wiki
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* Data+ and Data- must be a twisted pair. | * Data+ and Data- must be a twisted pair. | ||
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Revision as of 23:16, 4 October 2010
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.