Chauvet 648 Number of Fixtures DMX Data Cabling Making Your Own DMX Cable, DMX Cable Connectors

(DMX Connectivity cont.)

Number of Fixtures

DMX Data Cabling

Making Your Own DMX Cable

DMX Cable

Characteristics

When using a DMX controller, the combined number of channels required by all the fixtures on the DMX daisy chain determines the number of fixtures the DMX controller has to support. Conversely, the number of onboard sliders, page buttons, and fixture buttons limits the number of discrete DMX channels a DMX controller can support.

To comply with the EIA-485 standard, which is the base for the USITT DMX512-A protocol, do not connect more than 32 fixtures without using an optically-isolated DMX splitter. Doing otherwise may result in deterioration of the digital DMX signal.

You must use DMX compliant data cables to link two or more DMX compatible fixtures. You may purchase CHAUVET® certified DMX cables directly from a dealer/distributor or construct your own cable.

USITT recommends limiting the total length of the DMX cable (from the first fixture/controller to the last fixture) to 300~455 m (985~1,500 ft).

If you choose to create your own DMX cable, make sure to use data-grade cables that can carry a high frequency signal and are less prone to electromagnetic interference. Use a Belden® 9841 or equivalent cable, which meets the specifications for EIA RS-485 applications. For certain applications, Cat5, Cat5e, or Cat6 may be appropriate.

Do not use standard microphone cables for DMX applications because they cannot transmit DMX data reliably over long distances.

The DMX data cable must have the following characteristics:

Type:	shielded, 2-conductor twisted pair
Maximum capacitance between conductors:		30 pF/ft
Maximum capacitance between conductor and shield:		55 pF/ft
Maximum resistance:		20 ohms/1000 ft
Nominal impedance:		100~140 ohms

DMX Cable Connectors

Each DMX cable must have a male (3-pin or 5-pin XLR connector) on one end and a female (3-pin or 5-pin XLR connector) on the other end.

DMX Connector Configuration

To DMX Input		To DMX Output
(Female)		(Male)
1	Common
	DMX +	1
3		3
2	DMX -	2

To avoid signal transmission
problems and interference,	1
connect a DMX signal terminator	3
to the last fixture in the	2
DMX daisy chain, as shown.

120 ohm, ¼ W resistor between pin 2 (DMX -) and pin 3 (DMX +) on the output of the last fixture.

Impulse™ 648 User Manual Rev. 6 Page 19 of 21