Pioneer PDP-505CMX Command Reference Manual page 16

RS-232C Adjustment Mode
7 Check Sum
The Check Sum is data to which 2-Byte ASCII code is added to a data group that is returned by a GET command.
PC side
STX ID GET command
02 (hex) 2 Byte 3 Byte
.
Example) Check Sum value that is added when the GET command [GAA] returns the following 6-Byte data
Data group (ASCII)
+ check sum
The data group is put into binary code
one character at a time then displayed.
Only the last two digits are displayed.
*The returned data group is in capital English letters. Please keep this in mind when introducing it into
the binary code. .
7 Examples of check sum applications
Example 1) When the data is missing 1 Byte
STX
02 (hex)
data group is calculated according to rules set by a PC application
when these values are added, the result is 1C4 (hex)
value xx, where xx is 3C (hex), is added to 1C4 such that the last
check sum [OB (hex)] and the calculated [3C (hex)] do not match
Since they do not match, the PC application repeats the GET command
and retrieves the data again.
Example 2) When 1 Byte of data in the data is unreadable
STX
02 (hex)
data group is calculated according to rules by a PC application
when these values are added, the result is 1F7 (hex)
value xx, where xx is 09 (hex), is added to 1F7 such that the last
check sum [OB (hex)] and the calculated [09 (hex)] do not match.
Since they do not match, the PC application repeats the GET command
16
and retrieves the data again.
ETX
03 (hex)
Set side
STX
02 (hex)
GET command
GAA
47 41
when these values are added the result is 1F5 (hex)
xx, where xx is 0B (hex), is added to 1F5 so the last two digits are 00 (in this case 200)
as the data format, OB is converted to ASCII code and sent
The following data is output from the plasma display side.
STX GET command
02 (hex)
GET command Data
GAA 100 (missing data) 28
47 41 31 30 30 32 38
≠
two digits are 00 (in this case 200)
≠
≠
GET command Data
GAA 100328
47 41 31 30 33 30 32 38
≠
two digits are 00 (in this case 200)
≠
≠
GET command
3 Byte
Data (6 Byte)
100128
≠
41 31 30 30 31 32 38
≠
≠
≠
Data
GAA 100128
Check sum
0B
Check sum
0B
Data Check sum
*Byte 2 Byte
Check sum
xx (before calculation)
Check sum ETX
0B 03 (hex)
ETX
03 (hex)
ETX
03 (hex)
ETX
03 (hex)