Dmx Cabling - Chauvet Scorpion GVC User Manual

DMX Cabling

DMX Connectors
Scorpion™ GVC/RVM/RGY User Manual (Rev. 08)
The DMX protocol requires using special data cables to accommodate the high
speed digital signals. Despite their apparent similarities, data cables are electrically
different from standard microphone cables because they can carry high frequency
digital signals and have better protection against electromagnetic interference. You
can purchase CHAUVET® certified DMX cables directly from a dealer/distributor or
make your own DMX cable.
If you choose to make your own DMX cable, you must use a data-grade cable such
as the Belden 9841, which has the following electrical characteristics:
Type:
Maximum capacitance between conductors:
Maximum capacitance between conductor and shield:
Maximum resistance:
Nominal impedance:
Each DMX cable must have a male XLR connector on one end and a female XLR
connector on the other end. The DMX protocol indicates that the XLR connectors
must have five pins. However, most lighting products use the 3-pin XLR connector.
The pin assignment of the 3-pin and 5-pin XLR connectors in a DMX cable is as
follows:
Male Plug
Signal 3-Pin
Common
1
Data -
2
Data +
3
Not used
Not used
You can use the above table to create a 3-pin/3-pin cable, a 5-pin/5-pin cable, or a 3-
pin to 5-pin adapter.
The DMX daisy chain uses a terminator to reduce signal transmission problems,
especially with long cables. The terminator consists of either a 3-pin or 5-pin XLR
male plug with a 120 Ω, ¼ W resistor connected to the wire side of pins 2 and 3, as
shown below.
The terminator plug connects to the DMX Out socket of the last DMX product in the
daisy chain.
Do not allow the common wire of the DMX cable to touch the product's chassis
ground. This could cause a ground loop, which may affect your products'
performance. Test all DMX cables with an ohmmeter to verify the correct
polarity of the wires, and to make sure that they are not touching the shield or
each other.
shielded, 2-conductor twisted pair
30 pF/ft
55 pF/ft
20 ohms/1000 ft
100~140 ohms
Female Plug
5-Pin 5-Pin
1 1
2 2
3 3
4 4
5 5
3-Pin Signal
Common
1
Data -
2
Data +
3
Not used
Not used
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