Pelco C603M-A (11/07) manual Connecting Alarms, Supervised Alarms

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.

NORMALLY CLOSED			NORMALLY OPEN
NO ALARM	1 K		NO ALARM	1 K
GND		+V	GND	+V
ALARM	1 K	+V	ALARM	1 K
GND			GND	+V
ALARM	1 K		ALARM	1 K
GND		+V	GND	+V
	CUT			CUT
ALARM	1 K	+V	ALARM	1 K
GND			GND	+V

BYPASS

BYPASS

Figure 17. Supervised Alarm Conditions

22 C603M-A (11/07)