The methode I used is to send a zero byte in a slow bit rate (9600) before resuming to normal baudrate (19200).
I need to send a syncbreak (at least 13 consecutive bits in zero).
I use NONOVERLAPPED communication.
I wrote a "sendbreak" subroutine that changes baudrate to 9600,
sends a byte, than, changes baudrate back to 19200.
The problem I noticed is that on some computers the break signal is partialy executed, on others it is not executed at all. On all computers each of the lines of the routine performs perfectly when I set a "debug-break" before changing the baudrate back to 19200.
It seems that "WriteFile( ....,NULL) does not block execution before executing next line.
What can I do in order to assert that the message was fully executed on the hardware before executing next line?