8 Bit, ODD - parity (the parity bit completes the total of 1s to an odd figure)
Data flow control:
'STX' 'data' 'CHK' 'ETX'
XOR - connection of all data (without STX, ETX nor CHK)
OR connection of all single data bits with HEX 0x80 Therefore the highest bit (bit 7 resp. MSB) of the data and of the CHK always is 1.
Example data: ASC '1' = HEX 0x31 OR HEX 0x80 = HEX 0xB1.
But for "ETX" and "STX", the highest bit (MSB) is always 1.