RC Systems ViewSmart 1600+ Operation Manual page 32

3.4.4.3 Discrete Relay Option
Each Discrete Relay Option board provides 8 addressable relays for the ViewSmart 1600+.
IMPORTANT: Appropriate diode (DC loads) or MOV (AC loads) snubber devices must be
!
installed with inductive loads to prevent RFI noise spikes. Relay wiring should be kept separate
from low level signal wiring.
Terminals for the Discrete Relays are found on TB1 for channels 1/9, 3/11, 5/13, 7/15 and TB2 for channels
2/10, 4/12, 6/14, 8/16 (channels depend on the channel group assigned to the board).
Relay terminals are labeled NO for the Normally Open terminal, C for the Closed Terminal and NC for the
Normally Closed Terminal. The NO and NC nomenclature comes from the normal state of the relay (de-
energized state). The Fault Relay (or relays when placed in Failsafe Mode) is normally in the energized
state, and becomes de-energized when the Fault (alarm) condition is reached.
Only two wires are needed for wiring of relays. A typical wiring would have power wired to the C terminal,
and the NO and C terminals wired to the alarm device. Under normal operations the circuit between the
two terminals is open. When the alarm state is reached, the NO contact closes, and completes the circuit,
energizing the alarm device.
When a Standard Relay is configured for Failsafe Mode (or the Fault Relay), the alarm condition is used to
de-energize a device such as a Green Steady Light (all clear). In this case, the light is wired to the C and NO
terminals, and Power is wired to the C terminal just as described previously. However, since the relay is
in Failsafe mode, the circuit is complete, and the device is powered. When the alarm (fault) state is
reached, the relay de-energizes, and the light turns off. This is very useful for indicating a loss of power to
a device.
When powering multiple devices with the same voltage requirements, placing wires across the C terminals
of the relays with common load requirements can simplify wiring.
TB5 provides an open collector failure detection output. If communication is lost with the CPU board or if
the relay board's processor fails, the positive terminal of TB5 is pulled low.
After wiring is complete, the boards can be configured as described in Chapter 4.3.1.2.
UM-1097
Revision B 22