Pioneer 607CMX Technical Manual - Page 209

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 02 (hex) ID 2 Byte QUEST command 3 Byte ETX 03 (hex) Set side STX 02 (hex) QUEST command 3 Byte Data *Byte Check sum 2 Byte ETX 03 (hex) 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. Data group (ASCII) + check sum QUEST command QAA Data (6 Byte) 100128 Check sum xx (before calculation) ≠ The data group is put into binary code one 47 character at a time then displayed (only the 41 41 31 30 30 31 32 38 last two digits are displayed). 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 Data Check sum 02 (hex) QAA 100128 0B ETX 03 (hex) * The returned data group is in capital 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) QUEST command QAA Data 100 (missing data) 28 47 41 31 30 30 32 38 Check sum 0B ETX 03 (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) QUEST command QAA Data 100328 47 41 31 30 33 30 32 38 Check sum 0B ETX 03 (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 again and gets the data again. 209