Path: utzoo!attcan!uunet!snorkelwacker!usc!ucsd!ucbvax!IBM.COM!RAH
From: RAH@IBM.COM ("Russell A. Heise")
Newsgroups: comp.unix.aix
Subject: RTS/CTS flow control (AIX V3)
Message-ID: <101090.091906.heise1@ibm.com>
Date: 10 Oct 90 14:27:46 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 42


 kevin@msa3b.UUCP (Kevin P. Kleinfelter) writes:

 > How does one enable/disable RTS/CTS flow control on a tty line using
 > AIX V3, from a C program?  The only info provided by "info" is that
 > "stty add rts" can be issued from the shell level.
 >
 > I have issued "stty add rts" from the shell, then entered a C program that
 > puts the terminal in raw mode, and it appears that RTS/CTS flow control
 > is not enabled.  That is to say, a line monitor shows that data is
 > received, RTS is not dropped, yet the last few bytes of the data are
 > not returned by a "read" in my code.

 An associate offers the following sample program:
 --- cut here
 #include <termios.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <sys/errno.h>
 #include <fnctl.h>
 #define MODEM_LINE "/dev/tty1"
 main()
 LB            <== LB is left brace, RB is right brace
     int linefd;
     linefd = open (MODEM_LINE, O_RDWR);
     if (linefd == -1)
         printf ("Can't open line - errno %d\n", errno);
     else
         while (1) LB
             printf ("Drop RTS now\n");
             ioctl (linefd, TIOCMBIC, TIOCM_RTS);
             sleep (2);
             printf ("Raise RTS now\n");
             ioctl (linefd, TIOCMBIS, TIOCM_RTS);
             sleep (2);
         RB
 RB           <== supposed to be a right brace
 --- end cut here

 Of course, this code is offered without warranty.  Hope it helps.

Russ Heise, AIX Technical Support, IBM