TIOCMSET(2const) TIOCMSET(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 <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)
Linux man-pages 6.9.1 2024-06-13 TIOCMSET(2const)
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