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APPENDIX 2. –RS-232 Protocol
1. Setup
1.1 Use a Null Modem cable (the standard RS-232 9 Pin Cable with Pin 2 and Pin 3
exchanged, see pin configuration chart below for details) to connect the COM 1 on the rear
panel of the NVR-2028 to a PC.
NVR
1.2 Set the RS-232 option to ON in the COMMUNICATION page of the setup menu.
1.3 Set the PC communication parameters: 9600 bps, No Parity, 8 Data Bits, 1 Stop Bit.
2. Communication Protocol
2.1 General Command Format
<Lead Code = 0x41>, < Dest ID >, < Src ID >, <Main category >, <Second category >,
{<Number of parameters>,<Parameter 1>, <Parameter 2> ..,} <End Code= 0x4f>
Lead Code = 0x41
Dest ID = 0x01
Src ID = 0x20
Main Category = 0x01 Keys and Signals
= 0x02 Command
Second Category = 0x01 Handshake
= 0x02 Request Time/Set Time
= 0x06 Request System State
= 0x0b Time Search
End Code= 0x4f
The different command types and their corresponding parameters are as follows:
2.2 Keys and signals
PC Send: <0x41>, <0x01>, <0x20>, <0x01>, <Key Value(Low byte)>,
<Key Value(High byte)>,<0x4f>