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SMC sierra monitor corporation Sentry Instruction Manual - Version 6
PRODUCT DESCRIPTION
Page: 2
1.4 INTERCONNECT WIRING
Not supplied with Sentry, but necessary to the installation
and operation is the three conductor wiring which connects
the controller to the modules. Before this wiring is
installed it is important to read and understand the
installation instructions (Chapter 3) because significant
economies can be realized by connecting more than one
module onto a common wiring run. This standard feature
is accomplished by multiplexing the signals from the
modules to the controller.
1.5 DATA TRANSMISSION
Transparent to the user is the data transfer which occurs on
the installed interconnect wiring. Two of the conductors
are used to pass direct current (DC) from the controller to
the modules. The third wire transfers a series of very rapid
pulses between the controller and the sensor modules. This
digital transfer of information is an important feature of the
system which significantly reduces RFI and EMI problems.
1.6 POWER REQUIREMENTS
The standard system requires 120 VAC, 60 Hz, at 0.5 Amp
electrical supply. A factory option can be ordered for
220 VAC operation. DC voltage (12 to 28 VDC) can be
used for standby power. The system will automatically
switch to supplied DC operation at any time the AC
voltage is interrupted.
The system includes a lithium battery for RAM memory
retention during power interruptions. To ensure
continuous trouble free operation, however, the primary
power source must be one which is continuous and reliable,
preferably dedicated to this equipment. Battery back-up or
emergency power is recommended to insure continuous
operation.