Dahua NVR21-4KS3 Series User Manual page 79

No. Port Name
Alarm output port
(NO1-NO5, C1-C5, NC5)
RS-485 port (A, B)
CTRL
MIC IN
6
MIC OUT
7 HDMI port
8 USB port
Function
● Five groups of alarm output ports (Group 1: NO1-C1,
Group 2: NO2-C2, Group 3: NO3-C3, Group 4: NO4-C4,
Group 5: NO5, C5, NC5). Output alarm signal to the
external alarm device. Make sure power supply is
available for the external alarm device.
● NO: Normal open alarm output port.
● C: Alarm output public end.
● NC: Normal close alarm output port.
GND. Alarm input ground port.
● RS485_A port. Control cable A of the 485 device. It
connects external devices such as speed dome and PTZ.
● RS485_B port. Control cable B of the 485 device. It
connects external devices such as speed dome and PTZ.
Controllable 12 V power output. It is to control
the on-off alarm relay output. It can be used to
control the device alarm output. At the same
time, it can also be used as the power input
source of some devices such as alarm detector.
+12 V power output port. It can provide power to
some peripheral devices such as camera and
alarm device. Make sure the power supply of
peripheral device shall be below 1 A.
Bidirectional talk input port. It is to receive analog audio
signal from devices such as microphone, sound pickup.
Audio output port. It is to output analog audio signal to
devices such as sound box.
● Bidirectional talk output.
● Audio output on 1-window video monitor.
● Audio output on 1-window video playback.
High definition audio and video signal output port. It
transmits uncompressed high definition video and
multiple-channel audio data to displays with HDMI port.
The two HDMI ports support 2-channel high definition
HDMI output of different sources.
USB 3.0 port. Connect to devices such as mouse, USB
storage device and USB burner.
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User's Manual
The
two
ports
serve
as
anoth
er
group
of
alarm
output
ports.