Specifications

“Lighting Systems Made Easy” Page 33
dimmer outlets in the studio, multiple DMX outlets are distributed conveniently in the studio.
The outlets are set up to be DMX output or input because they have both a male and female 5-pin
XLR connectors on the same line. The outlets are an either or situation, if it is used for output you
cannot plug into the input and transmit DMX along the same line. Even this rule does not always
apply, if you make a special adapter it is possible to utilize the 4
th
and 5
th
cable, that is not used
according to DMX specifications, to transmit DMX on the same line. This practice must be closely
monitored to insure to DMX input does not inadvertently get connected to the DMX output signal.
Experience is the best teacher and the skilled crew at CBC has been using this system for several
years. The second device we will follow is a scroller. The scroller’s DMX input is connected to the
DMX output closest to the scroller. The DMX operator then chooses the DMX control source and
assigns the numbered DMX output that will control the scroller. The information is sent to the DMX
patch rack via computer and the specific input and output cables are electronically connected. The
DMX patch rack verifies the information transferred, via computer, and then sends a response to
the computer acknowledging the information. Automated devices like scrollers often require an
external non-dim power supply to operate. Non-dim power supply to operate. Non-dim power is
supplied next to every DMX outlet in the studio. Studio 42 has DMX controlled relays to turn the
non-dim power individually on and off. All of the relays have individual DMX addresses so they
can be individually controlled by the lighting console.
The system also allows control signals other than DMX to be transmitted along the DMX cable.
When connecting an alternate control protocol the outlet is deselected from the DMX patch rack
making it possible to physically input the control protocol to one of the inputs on the rack. With this
flexibility an automated light that operates on its own protocol can be powered by the non-dim
power supply then plugged into the DMX outlet. The control signal is sent to the rack then physi-
cally distributed, with jumper cables, to the specific outlets connected to the automated light. Many
automated consoles incorporate DMX output to control peripheral equipment while simultaneously
transmitting an alternate control signal to the automated lights. The DMX output can be used to
power the DMX non-dim relays on and off making all the control originating from the same lighting
console.
The Studio 42 DMX network is one example of an efficiently operating DMX network installation.
Advances in DMX distributions have spawned current devices on the market that allow DMX to be
sent without wires. Radio DMX is available from several manufacturers. The techniques used
vary between manufacturers but the result is wireless DMX. Transmitters are connected to the
DMX output from the console and the receiver is connected to the DMX device to be controlled.
Cable distribution could be an economical alternate from the receiver rather than multiple receivers
at every DMX device. Radio DMX makes it possible to control devices where cable distribution is
impractical. For example multiple self-powered lighting rigs on a parade float could be controlled
from a distant lighting console. DMX-512 is the common ground for all manufacturers in the light-
ing industry. As I have briefly outlined this control protocol requires attention to some basic opera-
tion techniques. Adherence to these techniques, when designing and implementing a DMX net-
work will insure your DMX devices will operate to their maximum potential.
Brad Dickson is the Lighting Director/Lighting Instructor at the Canadian Broadcasting Corporation
in Toronto, with over 20 years experience at CBC Lighting. He is an Executive Board Member of
the Society of Television Lighting Directors, webmaster of the STLD website and a member of
SMPTE.