TIOCMBIC(2const)

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 <asm/termbits.h>
#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);
}