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DVR-3901 Installation and Operation Manual 49
Chapter 4: Remote Operation
UDP Control
The DVR-3901 implements UDP remote control over an Ethernet port.
UDP Communication Over Ethernet Port
You can use the external Ethernet port to control the DVR-3901 by
sending serial control protocol commands encapsulated in UDP
packets. UDP communication is conducted on port 331. This method
requires that the content of server/client conversation bear the format
outlined in
Table 4-3 :
Table 4-3. UDP Datagram Format
Field Format Description
ID 4 bytes,
unsigned,
MSB first This field contains he ID number of a
command or response.
It should have different values for adjacent
commands. For example, this field can be
an incrementing count number modulo
2^32, unless the command is a retry of the
previous command, for example, resulting
from a response time out. The retried
command will bear the same ID number as
the original (failed) command.
CHANNEL 1 byte,
unsigned This field should be 0.
DATA0 -
DATA(N-1) N-byte, size
depends on
command This field contains either a command from
the controlling device or a response from
the controlled device.
Referring to Table 4-1, this field contains
all the bytes in the command except the
checksum.