3.3. Bytes of a packet
Byte 0:
Header
It must be the ASCII code ‘*’ (2A hex)
Byte 1:
High character of camera ID
Byte 2:
Low character of camera ID
Ex) current camera ID : 43 decimal
43 decimal = 2B hex
Byte 1: ASCII code ‘2’(32 hex)
Byte 2: ASCII code ‘B’(42 hex)
Byte 3, Byte 4:
Command
Byte 5 ~ Byte 8:
Option of command
Byte 9:
High byte of check sum
Byte 10:
Low byte of check sum
3.4. Check Sum Method
The value of check sum is calculated as follows:
Check Sum = Byte0 + Byte1+ … + Byte8
Ex) if ID = 43 d (2B hex), command = 75 hex,
command option = 0000
command byte0~byte8 : * 2B 75 0000
ASCII format: 2A 32 42 37 35 30 30 30 30
Sum = 2A+32+42+37+35+30+30+30+30
= 1CA hex
So, the Check Sum = CA
So the complete command packet.
= * 2B 75 0000 CA
Doc # APN 20/21Z704 22X
Comm.
Issue Date: 3/25/2005
Revision: E
Page
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