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C613M-A (5/05) 17
CONNECTING ALARMS
The SP04-140 offers three alarm inputs for external signaling devices, such as door contacts or motion detectors. Each encoder supports either
all normally open or all normally closed devices. If your installation requires mixed devices, install another SP04-140, NET5301T, or a NET5301R
video decoder. Then connect the normally open devices to one unit and the normally closed devices to the other unit.
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 NVR5100 Series recorder. You can connect switches or contacts directly
to the unit without a separate power supply.
Each encoder supports either all supervised or all unsupervised alarms. If your installation requires mixed alarm types, install another SP04-140,
NET5301T, or a NET5301R video decoder. Then connect the supervised alarm inputs to one unit and the unsupervised alarm inputs to the other
unit.
Supervised Alarms
When an alarm is configured as a supervised alarm, the SP04-140 maintains a constant electrical current through the alarm circuit (3.3 VDC,
1 k
Ω
). 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 k
Ω
resister as close to the switch as possible.
Figure 14 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 14.
Supervised Alarm Conditions
NORMALLY OPEN
NORMALLY CLOSED
ALARM
GND
+V
+V
ALARM
GND
+V
+V
ALARM
GND
CUT
NO ALARM
GND
ALARM
GND
+V
+V
+V
+V
ALARM
GND
BYPASS
CUT
BYPASS
NO ALARM
GND
ALARM
GND
1 K
1 K
1 K
1 K
1 K
1 K
1 K
1 K