When transmitting a byte, the RS232 first sends a START BIT (0),
followed by the data (general 8 bits, but could be 5, 6, 7, or 8 bits),
followed by parity bit (If no parity then there is no parity bit ) followed
by STOP BITs(one or two bit)(1). The sequence is repeated for each
byte sent. Show in picture below
Data stream = bits are transmitted from least significant bit (LSB)
to most significant bit (MSB),
“A” = binary is 01000001
Data stream = 10000010
The parity characteristic can be even, odd, mark, space, or none.
last data bit = 1 if the data transmitted had an even amount of 0 bits.
last data bit = 1 if the data transmitted had an odd amount of 0 bits.
last data bit = 1
last data bit = 0
no parity bit transmitted
Example the bit stream transmitted
RS232 setting = characteristics 8 bits, no parity, 1 stop
Data = ‘A’
bit stream transmitted = start bit – data – one stop bit
bit stream transmitted = 0 1 0 0 0 0 0 1 0 1