Serial Port - Hardware Flow control

Hi all,

I am writing routines for the serial port and I was wondering if setting the QNX (POSIX) flags “IHFLOW” and “OHFLOW” would have the same effect as setting the Linux “CRTSCTS” (Non-Posix) bit to enable hardware flow control?

eg: tio.c_cflag |= IHFLOW; // Enable INPUT hardware control
tio.c_cflag |= OHFLOW; // Enable OUTPUT hardware control
(Where “tio” is a termios struct)

Is the same as :
tio.c_cflag |= CRTSCTS; ???
As always, any help is very much appreciated.


Hey keano,

IHFLOW and OHFLOW control the rts and cts (hardware handshake) lines.



Thanks for the reply Martin,
Will the code have the same effect as the Linux version however?

They have the same effect.