Pathway DMX Pathfinder CR Manual - Manual (Page 26)

DMX Distribution System Page 26
Maintenance and Testing
System testing by maintenance personnel will usually be carried out in response to
a fault that has developed somewhere in the system. Powerful diagnostic
instruments are available to assist the maintenance technician with his task: the
Fluke Model 650 LAN CableMeter, and Goddard Design Li'l DMX'ter. These will be
described in more detail below. In general, though, the procedures outlined in 1.5
Basic Troubleshooting and 2.3 Advanced Troubleshooting are likely to solve the
vast majority of problems encountered, especially where any system downtime
cannot be tolerated.
Tests using instrumentation will be performed where anomalies have developed in
the system that cannot be isolated with standard troubleshooting procedures.
Additionally, testing can establish minimum network performance where non-
DMX512 control equipment is to be connected to the system.
.1 Fluke 650 LAN CableMeter -- Please refer to the manufacturer's user's
manual for detailed instructions before attempting to use this instrument.
The Fluke 650 is provided with a battery-powered remote plug-in unit, a set
of 2 adapter cables (RJ45 to 5-pin XLR) and an AC adapter. The unit may
be powered by a 9-volt alkaline battery, but battery life tends to be rather
short with the 650 so use of the AC adapter is recommended.
When the remote unit is connected to the other end of any DMX cable run,
the 650 will verify wiring continuity on all pins except ground (pin 1). Cable
length can also be measured with the instrument, and any anomalies, e.g.
changes in line impedance will be detected. The 650 measures performance
of the cable installation at up to 10 million bits per second.
The Fluke 650's signalling is not compatible with the distribution rack
electronics or any other DMX generating or receiving equipment. Thus its
usage is confined to the cable installation only.
.2 Goddard Design Li'l DMX'ter -- This useful instrument can test most
aspects of the DMX Distribution System, from wiring continuity to signal
propagation through the rack electronics. Since the DMX'ter can both
generate and receive DMX512, it is 100% compatible with all aspects of the
distribution system, including any control system or receiving device. The
DMX'ter will directly control any receiving unit, and will verify the output of a
controller by displaying the data on an LCD readout. In addition, the