We've launched our new site at www.openlighting.org. This wiki will remain and be updated with more technical information.
Talk:DMX512-A
From wiki.openlighting.org
Contents
Timings
The clock rate is 250 kHz so each symbol bit on the wire is 4 microseconds long (period time).
Frame rate is ?? Packet rate is typically around 44 Hz when all frames are sent.
RDM protocol additions
The name of the standard is: ANSI/ESTA 1.20, Entertainment Technology - Remote Device Management over USITT DMX512 ??? Mark (beginning of frames) Mark After Break (beginning of frames)
Mark time between packet Mark time between frames
Use of category 5 UTP or STP
New cable types is used, and may be officially accepted. http://www.usitt.org/standards/DMX512_FAQ.html#FAQ_08
The use of modular plugs like 8P8C (RJ45) or 6P4C (RJ11)
The cabling for DMX512-A should be described in the document called "BSR E1.27-1 -- Portable Control Cables for Use with USITT DMX512/1990 and E1.11 [DMX512-A]"
Sender/receiver topologiess
To avoid ground loops and improve reception performance, transmitters and/or receivers can be grounded/floating/non-isolated ??? http://www.usitt.org/standards/DMX512_FAQ.html#FAQ_15 There are different topologies, and not all will work together. There are no requirement for what topology to use in the DMX specification from 1990, so it was added to DMX512-A.
Transmitters should use "earth ground" as a reference for the positive/negative voltages that is put on the two data lines. If they don't, it must be clearly marked on the product and in the manual. Receivers should be ...?
