Alarm Connection; Alarm Port; Alarm Input Port - Dahua NVR21-4KS3 Series User Manual

2.3 Alarm Connection

2.3.1 Alarm Port

The alarm port is shown as below. The following figure is for reference only.
Icon
1–16
NO1 C1, NO2 C2, NO3
C3, NO4 C4
NO5 C5 NC5
CTRL (CTRL 12 V)
P (+12 V)
A/B
● Different models support different alarm input ports. Please see the specifications sheet for
detailed information.
● Slight difference might be found on the alarm port layout.

2.3.2 Alarm Input Port

Connect the positive end (+) of the alarm input device to the alarm input port (ALARM IN 1–16) of
the NVR. Connect the negative end (-) of the alarm input device to the ground end (
Figure 2-117 Alarm port
Table 2-48 Alarm port description
Function
ALARM1–ALARM16. The alarm becomes activated in the low level.
Four NO activation output groups. (On-off button).
One NO/NC activation output group. (On-off button).
Control power output. Disable power output when alarm is canceled.
Current is 500 mA.
Rated current output. Current is 500 mA.
GND.
485 communication port. They are used to control devices such as
PTZ. Please parallel connect 120 TΩ between A/B cables if there are
too many PTZ decoders.
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User's Manual
) of the NVR.