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:

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)