Leprecon VX Dimmer - Manual (Page 12)

12
8. Appendix A DMX 512 Standards
The following information is a summary of the USITT 1990 standard for dimmers and controllers.
A complete copy may be obtained from:
USITT
10 W. 19th ST.
Suite 5A
New York, NY 10011-4206
The DMX 512 standard is designed as a simple, reliable system for connecting digital dimmers
and controllers. The protocol allows up to 512 dimmers to be connected to a single control
console. With 512 dimmers in a system, DMX 512 allows each dimmer level to be updated as fast
as 44 times each second.
As far as the users of DMX equipment are concerned, three things matter more than the electrical
specifications contained in the DMX description. The most important items are connectors, cable
and how to wire the two ends together.
DMX 512 currently uses 3 pins of a 5 pin connector. The two unused pins are reserved for future
use, some manufacturers are using these pins for communications back from the dimmer to the
control console, or as a redundant data line. At this time, DMX cables are being used that only
contain 3 wires. If you wish to include the capability to use the extra pins, it is suggested that you
buy or make cables with all 5 pins connected.
The connectors to be used for DMX 512 are as follows:
Console end (transmitter) Female 5 pin XLR
Dimmer end (receiver) Male 5 pin XLR
The 5 pin XLR is very similar to the 3 pin connectors used for microphone cable. Some
manufacturers of XLR connectors are Switchcraft, ITT Cannon, and Neutrik.
Cable type:
Shielded twisted pair approved for EIA-422/EIA-485 use. Either one pair with shield or two pair
with shield may be used. Examples of such cable are:
Single pair: Belden 9841, Alpha 5271
Two pairs: Belden 9842, Alpha 5272
The Pin Designations for DMX 512 are as follows:
Pin 1 Signal common (cable shield)
Pin 2 Data 1-
Pin 3 Data 1+
Pin 4 Spare, optional Data 2-
Pin 5 Spare, optional Data 2+