Pioneer PDP-425CMX Technical Manual page 184

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.
PC side
STX ID QUEST command
02 (hex) 2 Byte
A detailed example will be given below.
Example) The check sum value that is added when the QUEST command QAA returned the following 6-Byte data.
Data group (ASCII)
+ check sum
The data group is put into binary code one
character at a time and displayed (only the
last two digits are displayed).
* The returned data group will be in capital English letters. Please keep this in mind when introducing it into
the binary display.
7 Examples of check sum applications
Example 1) When the data is missing 1 Byte
STX
02 (hex)
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).
Here, the check sum [OB (hex)] and the calculated [3C (hex)] do not match.
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
STX
02 (hex)
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).
Here, the check sum [OB (hex)] and the calculated [09 (hex)] do not match.
Since they do not match, the PC application sends the QUEST command
184
again and gets the data again.
ETX
3 Byte 03 (hex)
Set side
STX
02 (hex)
QUEST command
QAA
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 QUEST command
02 (hex)
QUEST command Data
QAA 100 (missing data) 28
47 41 31 30 30 32 38
≠
≠
≠
QUEST command Data
QAA 100328
47 41 31 30 33 30 32 38
≠
≠
≠
QUEST command
3 Byte
Data (6 Byte)
100128
≠
41 31 30 30 31 32 38
≠
≠
≠
Data
QAA 100128
Check sum
0B 03 (hex)
Check sum
0B 03 (hex)
Data Check sum
*Byte 2 Byte
Check sum
xx (before calculation)
Check sum ETX
0B 03 (hex)
ETX
ETX
ETX
03 (hex)