hardware flow control on /dev/ttySAC0

Hi all

I can send data on serial port /dev/ttySAC0 without hardware flow control:
newtio.c_cflag = baudrate | CS8 | CLOCAL | CREAD;

but with enabling hardware flow control 
newtio.c_cflag = baudrate | CRTSCTS | CS8 | CLOCAL | CREAD;
I see freezing system for several seconds after unsuccessful writing to
port.

(Before, I removed console definition for "/dev/ttySAC0" from linux boot -
Supervivi) 

I will be appreciated with your comments & suggestions.


regards

linux-2.6.32.2
Qt 4.8.0

res = write(fd,buf,size);
res is greater than zero, but I dont see wrote string on port.

In fact, I don't see anything on port

sorry, solved