Appendix – Blizzard Lighting 100 HushPar Infiniwhite User Manual

Page 14

Page 14

HushPAR InfiniWhite 100 Manual Rev. A

5. APPENDIX

A Quick Lesson On DMX

DMX (aka DMX-512) was created in 1986 by the United States

Institute for Theatre Technology (USITT) as a standardized method

for connecting lighting consoles to lighting dimmer modules. It was

revised in 1990 and again in 2000 to allow more flexibility. The

Entertainment Services and Technology Association (ESTA) has

since assumed control over the DMX512 standard. It has also been

approved and recognized for ANSI standard classification.

DMX covers (and is an abbreviation for) Digital MultipleXed signals. It

is the most common communications standard used by lighting and

related stage equipment.

DMX provides up to 512 control “channels” per data link. Each of these

channels was originally intended to control lamp dimmer levels. You

can think of it as 512 faders on a lighting console, connected to 512

light bulbs. Each slider’s position is sent over the data link as an 8-bit

number having a value between 0 and 255. The value 0 corresponds to

the light bulb being completely off while 255 corresponds to the light

bulb being fully on.

DMX data is transmitted at 250,000 bits per second using the RS-485

transmission standard over two wires. As with microphone cables,

a grounded cable shield is used to prevent interference with other

signals.

There are five pins on a DMX connector: a wire for ground (cable

shield), two wires for “Primary” communication which goes from

a DMX source to a DMX receiver, and two wires for a “Secondary”

communication which goes from a DMX receiver back to a DMX source.

Generally, the “Secondary” channel is not used so data flows only from

sources to receivers. Hence, most of us are most familiar with DMX-

512 as being employer over typical 3-pin “mic cables,” although this

does not conform to the defined standard.

DMX is connected using a daisy-chain configuration where the source

connects to the input of the first device, the output of the first device

connects to the input of the next device, and so on. The standard

allows for up to 32 devices on a single DMX link.