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NV3128 RS-422A Machine-Control Data Switch 1-3
CHAPTER 1 - GENERAL INFORMATION
1.1 GENERAL
The NV3128 is a serial digital switch for routing RS-422A machine-control
data in a video or audio broadcast or production facility. Table 1.1 at the end
of this section lists its performance specifications.
Requiring only eight units of a 19" EIA rack for a bi-directional, 128-machine
array, the NV3128 achieves a 10:1 space reduction over traditional analog or
relay routers. Its non-blocking matrix architecture and unique dynamic port-
configuration capability combine to vastly simplify the cumbersome routing
of duplex machine-control signals. The system is capable of multidrop
RS422-A chains without bus contention.
At the heart of the NV3128 is the Control Card/Command Interpreter, which
parses the command strings from any of a large number of commonly available
router-control systems into physical from and to crosspoint addresses. Further,
the Interpreter gleans from those commands the information it needs to
configure the I/O ports. Transparently, the Interpreter allows the NV3128 to
be steered by the same routing-control system that drives a plants program
and other auxiliary data switching.
The NV3128 can be synchronized to a video black burst signal or it can free
run. Takes occur during the vertical retrace interval of the video reference, or
during a calculated recreation of that interval if video is not present.
Router control systems typically communicate over serial RS-422A lines,
and this is what the new Universal Control Card uses. The obsolete Command
Interpreter card used in older models additionally supported RS-232 and a
parallel RS-422A implementation for such hardware interfaces as the Horizon
control protocol.
PC-compatible software furnished with the unit provides extensive
configuration, query and diagnostic utilities. Finally, should it prove undesirable
to merge the machine data route-control system into the program control, the
NV3128 comes with a simple, easy-to-use PC-based control system.
To enhance system reliability, the NV3128 frame houses an optional, fully
redundant 80-watt power supply. The outputs of the first and second supplies
share the load equally, but in the event of a failure, either can handily power
the system solo. Sensing circuitry activates an alarm relay on each power
supply, with contacts brought out for operating an external alarm. In the event
of a power failure, a one farad capacitor charge maintains power on a backup
SRAM bank, keeping the mapping of the switch intact for no less than 3 days.