Dahua NVR21-4KS3 Series User Manual page 81

No. Port Name
4 HDMI port
5 VGA port
6 RS-232 port
Alarm input port (1-
16)
Alarm output port
(NO1-NO5, C1-C5,
NC5)
7
RS-485 port (A, B)
CTRL
Function
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.
VGA video output port. Output analog video signal. It can
connect to the monitor to view analog video.
It is for general COM debugging to configure IP address and
transfer transparent COM data.
● There are four groups: 1-4, 5-8, 9-12 and 13-16.
They receive signals from external alarm source. Alarm
input includes two types; NO (normal open) and NC (normal
close).
● When your alarm input device is using external power,
make sure the device and the NVR have the same GND.
● 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.
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User's Manual