NAME

       TIOCMGET, TIOCMSET, TIOCMBIC, TIOCMBIS, TIOCMIWAIT, TIOCGICOUNT - modem control

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <asm/termbits.h>  /* Definition of TIOC* constants */
       #include <sys/ioctl.h>

       int ioctl(int fd, TIOCMGET, int *argp);
       int ioctl(int fd, TIOCMSET, const int *argp);
       int ioctl(int fd, TIOCMBIC, const int *argp);
       int ioctl(int fd, TIOCMBIS, const int *argp);
       int ioctl(int fd, TIOCMIWAIT, int arg);
       int ioctl(int fd, TIOCGICOUNT, struct serial_icounter_struct *argp);

       #include <linux/serial.h>

       struct serial_icounter_struct;

DESCRIPTION

       TIOCMGET
              Get the status of modem bits.

       TIOCMSET
              Set the status of modem bits.

       TIOCMBIC
              Clear the indicated modem bits.

       TIOCMBIS
              Set the indicated modem bits.

       The following bits are used by the above ioctls:

       TIOCM_LE    DSR (data set ready/line enable)
       TIOCM_DTR   DTR (data terminal ready)
       TIOCM_RTS   RTS (request to send)
       TIOCM_ST    Secondary TXD (transmit)
       TIOCM_SR    Secondary RXD (receive)
       TIOCM_CTS   CTS (clear to send)
       TIOCM_CAR   DCD (data carrier detect)
       TIOCM_CD    see TIOCM_CAR
       TIOCM_RNG   RNG (ring)
       TIOCM_RI    see TIOCM_RNG
       TIOCM_DSR   DSR (data set ready)

       TIOCMIWAIT
              Wait  for  any  of  the  4  modem  bits (DCD, RI, DSR, CTS) to change.  The bits of
              interest are specified as a bit mask in arg, by  ORing  together  any  of  the  bit
              values,  TIOCM_RNG,  TIOCM_DSR,  TIOCM_CD,  and  TIOCM_CTS.   The caller should use
              TIOCGICOUNT to see which bit has changed.

       TIOCGICOUNT
              Get counts of input serial line interrupts (DCD, RI, DSR,  CTS).   The  counts  are
              written to the serial_icounter_struct structure pointed to by argp.

              Note:  both  1->0  and 0->1 transitions are counted, except for RI, where only 0->1
              transitions are counted.

RETURN VALUE

       On success, 0 is returned.  On error, -1 is returned, and errno is  set  to  indicate  the
       error.

EXAMPLES

       Check the condition of DTR on the serial port.

       #include <fcntl.h>
       #include <stdio.h>
       #include <sys/ioctl.h>
       #include <unistd.h>

       int
       main(void)
       {
           int fd, serial;

           fd = open("/dev/ttyS0", O_RDONLY);
           ioctl(fd, TIOCMGET, &serial);
           if (serial & TIOCM_DTR)
               puts("TIOCM_DTR is set");
           else
               puts("TIOCM_DTR is not set");
           close(fd);
       }

SEE ALSO

       ioctl(2), ioctl_tty(2)