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C3446M (7/08) 19
CONNECTING ALARMS
The Spectra Mini IP provides an alarm input for external signaling devices, such as door contacts or motion
detectors. Both normally open and normally closed devices are supported.
SUPERVISED ALARMS
When an alarm is configured as a supervised alarm, Spectra Mini IP maintains a constant electrical
current through the alarm circuit (3.3 VDC, 1 kohm). If the alarm circuit length changes, due to an electrical
short or a bypass, the voltage fluctuates from its normal state. Therefore, the unit triggers an alarm.
NOTE: Install the 1 kohm resistor as close to the switch as possible.
Figure 12 shows the alarm and no alarm conditions of a supervised alarm input. Whether the alarm is
normally closed or normally open, neither a cut nor a bypass can defeat these alarms.
Figure 13 and Figure 14 illustrate the wiring configuration for supervised alarm inputs.
Figure 12. Supervised Alarm Conditions
Figure 13. Normally Closed Supervised Alarm Input Wiring
Figure 14. Normally Open Supervised Alarm Input Wiring
NORMALLY OPEN
NORMALLY CLOSED
ALARM
GND
+V
+V
ALARM
GND
+V
+V
ALARM
GND
CUT
NO ALARMNO ALARM
GND
ALARM
GND
+V
+V
+V
+V
ALARM
GND
BYPASS
CUT
BYPASS
GND
ALARM
GND
1K
1K
1K
1K
1K
1K
1K
1K
1 K
1 K