Pioneer Plasma Display Panel PDP-425CMX - Manual (Page 19)

19
RS-232C Adjustment
7 Check Sum
This is data to which 2-Byte ASCII code is added to a data group returned by a QUEST command.
STX
02 (hex) 2 Byte 3 Byte 03 (hex)
ID QUEST command ETX
STX
02 (hex)
QUEST command
3 Byte
Data
*Byte
Check sum
2 Byte
ETX
03 (hex)
PC side
Set side
A detailed example is given below.
Example) The check sum value that is added when the QUEST command “QAA” returned the following 6-Byte data string.
QUEST command
QAA
Data (6 Byte)
100128
Data
100128
Check sum
0B
ETX
03 (hex)
Check sum
xx (before calculation)
Data group (ASCII)
+ check sum
47 41 41 31 30 30 31 32 38
When these values are added the result is 1F5 (hex).
As the data format, OB is converted to ASCII code and sent.
The following data is output from the Plasma Display side.
xx, where xx is 0B (hex), is added to 1F5 so the last two digits are 00 (in this case 200).
≠
≠
≠
≠
STX
02 (hex)
QUEST command
QAA
The data group is put into binary code one
character at a time then displayed (only the
last two digits are displayed).
7 Examples of check sum applications
Example 1) When the data is missing 1 Byte
47 41 31 30 30 32 38
Here, the check sum [OB (hex)] and the calculated [3C (hex)] do not match.
Data
100 (missing data) 28
Check sum
0B
ETX
03 (hex)
STX
02 (hex)
QUEST command
QAA
The data group is calculated according to rules by a PC application,
and when these values are added the result is 1C4 (hex).
≠
≠
≠
A value xx, where xx is 3C (hex), is added to 1C4 such that the last
two digits are 00 (in this case 200).
Since they do not match, the PC application sends the QUEST command
again and gets the data again.
Example 2) When 1 Byte of data in the data is unreadable
47 41 31 30 33 30 32 38
Here, the check sum [OB (hex)] and the calculated [09 (hex)] do not match.
Data
100328
Check sum
0B
ETX
03 (hex)
STX
02 (hex)
QUEST command
QAA
The data group is calculated according to rules by a PC application,
and when these values are added the result is 1F7 (hex).
≠
≠
≠
A value xx, where xx is 09 (hex), is added to 1F7 such that the last
two digits are 00 (in this case 200).
Since they do not match, the PC application sends the QUEST command
again and gets the data again.
* The returned data group is in capital letters. Please keep this in mind when introducing it into the binary
display.