Check Code - NEC LCD4020-BK-AV - 40IN LCD 1200:1 1366X768 60HZ Dvi-d 8MS Manual

"Command reply message" format depends on each command.
Refer to section 5.5 "Commands message" for more details.

4.5 Check code

Check code is the Block Check Code (BCC) between the Header and the End of Message except SOH.
D = D XOR D
n+1 1 2
XOR: Exclusive OR
Following is an example of a Check code (BCC) calculation.
Destination
SOH Reserved
Address
01 30 41
D D D
0 1 2
Check code (BCC) D
4.6 Delimiter
Packet delimiter code; ASCII CR(0Dh).
Header
SOH D
0
Reserved D
1
Destination D
2
Source D
3
Type D
4
Length D
5
STX D
6
Data D
7
| |
| |
ETX D
n
Check code D
n+1
XOR D XOR ,,, D
3 n
Header
Source Message
Message length
Address type
30 45 30
D D D
3 4 5
= D xor D
17 1
= 30h xor 41h xor 30h xor 45h xor 30h xor 41h
xor 02h xor 30h xor 30h xor 31h xor 30h xor 30h
xor 30h xor 36h xor 34h xor 03h
= 77h
Header Message
Message Check code
7 6 5 4
2 2 2 2
P P P P
OP code
STX
page
41 02 30 30
D D D D
6 7 8 9
xor ... xor D
xor D
2 3 14
Check code
(5/40)
Delimiter
3 2 1 0
2 2 2 2
P P P P
Message
OP code Set Value
31 30 30 30 36 34
D D D D D D
10 11 12 13 14 15
xor D xor D
15 16
Delimiter
Check
code Delimiter
ETX
(BCC)
03 77 0D
D D D
16 17 18