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8. UNDERSTANDING DMX
DMX-512:
DMX is short for Digital Multiplex. This is a universal protocol used by most
lighting and controller manufactures as a form of communication between intelligent
xtures and controllers. DMX allows all makes and models of different manufactures to
be linked together and operate from a single controller. This is possible as long as all
the xtures and the controller are DMX compliant. A DMX controller sends the DMX data
instructions to the xture allowing the user to control the different aspects of an intelligent
light. DMX data is sent out as serial data that travels from xture to xture via data “IN” and
data “OUT” XLR terminals located on the xtures (most controllers will only have output
jacks).
DMX Linking:
To ensure proper DMX data transmission, always use proper DMX
cables and a terminator. When using several DMX xtures try to use the shortest cable
path possible. Never split a DMX line with a “Y” style connector. The order in which the
xtures are connected in a DMX line does not inuence the DMX addressing. For example;
a xture assigned a DMX address of 1 may be placed anywhere in the DMX chain, at the
beginning, at the end, or anywhere in the middle. The DMX controller knows to send data
assigned to address 1 to that xture no matter where it is located in the DMX chain. The
Fixture be controlled via DMX-512 protocol. The Fixture is a 9-channel DMX xture. The
DMX address is set electronically using the controls on the LED menu.
Data Cable (DMX Cable) Requirements (For DMX and Master/Slave
Operation):
Your xture and your DMX controller require a standard 3-pin or 5-pin XLR
connector for data input and data output (the gure on the next page is of a 3-Pin XLR
connector). If you are making your own cables, be sure to use two conductor shielded
digital DMX cable rated at 120 ohms; this cable is designed for DMX transmission and
may be purchased from your Elation dealer or at most professional lighting retailers. Your
cables should be made with a male and female XLR connector on either end of the cable.
Also, remember that a DMX line must be daisy chained and cannot be split, unless using
an approved DMX splitter .
Be sure to follow the above gure when making your own cables. Do not use the ground
lug on the XLR connector. Do not connect the cable’s shield conductor to the ground lug or
allow the shield conductor to come in contact with the XLR’s outer casing. Grounding the
shield could cause a short circuit and erratic behavior.
DMX-512 control connection
Connect the provided XLR cable to the female 3-pin XLR output of your controller and the
other side to the male 3-pin XLR input of the xture. You can chain multiple xture together
through serial linking. The cable that should be used is two conductor, shielded DMX cable
with XLR input and output connectors. Always be sure daisy chain your in and out data
connections, never split or “Y” your DMX connections unless you are using an approved
DMX splitter
Fixture DMX addressing
All xtures should be given a DMX starting address when using a DMX controller, so the
correct xture responds to the correct control signal. This digital starting address is the
channel number from which the xture starts to “listen” to the digital control information
sent out from the DMX controller. The allocation of this starting DMX address is achieved
by setting the correct DMX address on the digital display located on the base of the xture.
