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

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.

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); }

Standard C library (libc, -lc)

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

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

ioctl(2), ioctl_tty(2) Linux man-pages 6.9.1 2024-06-13 TIOCMSET(2const)

#include<asm/termbits.h> /* Definition of TIOC* constants */ #include<sys/ioctl.h>intioctl(intfd,TIOCMGET,int*argp);intioctl(intfd,TIOCMSET,constint*argp);intioctl(intfd,TIOCMBIC,constint*argp);intioctl(intfd,TIOCMBIS,constint*argp);intioctl(intfd,TIOCMIWAIT,intarg);intioctl(intfd,TIOCGICOUNT,structserial_icounter_struct*argp);#include<linux/serial.h>structserial_icounter_struct;