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22 C603M-A (11/07)
CONNECTING ALARMS
The NET5301T-I offers three alarm inputs for external signaling devices, such as door contacts or motion detectors. Each encoder supports both
normally open and normally closed devices. Each encoder also supports both supervised and unsupervised alarms.
Once configured, an alarm input can invoke many different activities, including triggering a relay device, sending an alert to a security office,
changing the video recording settings, and storing pre-alarm video to an Endura video recorder. You can connect switches or contacts directly to
the unit without a separate power supply.
Supervised Alarms
When an alarm is configured as a supervised alarm, the NET5301T-I maintains a constant electrical current through the alarm circuit (3.3 VDC,
1 kohms). 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 17 illustrates 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 17. Supervised Alarm Conditions
NORMALLY OPEN
NORMALLY CLOSED
ALARM
GND
+V
+V
ALARM
GND
+V
+V
ALARM
GND
CUT
NO ALARM
GND
NO ALARM
GND
ALARM
GND
+V
+V
+V
+V
ALARM
GND
BYPASS
CUT
BYPASS
ALARM
GND
1K
1K
1K
1K
1K
1K
1K
1K