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#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/serial.h>
int openserial(char *devicename)
{
int fd;
if ((fd = open(devicename, O_RDWR)) == -1) {
perror("openserial(): open()");
return 0;
}
return fd;
}
int setRS485(int fd, int state)
{
struct serial_rs485 rs485;
if (ioctl(fd, TIOCGRS485, &rs485) == -1) {
perror("TIOCGRS485");
return 0;
}
//printf("Old RS485 flags %x\n", rs485.flags);
if (state)
rs485.flags |= SER_RS485_ENABLED;
else
rs485.flags &= ~SER_RS485_ENABLED;
if (ioctl(fd, TIOCSRS485, &rs485) == -1) {
perror("TIOCSRS485");
return 0;
}
//printf("New RS485 flags %x\n", rs485.flags);
return 1;
}
int main(int argc, char *argv[])
{
int fd;
if (argc != 3) {
printf("Usage: set_rs485hd tty 0|1\n");
return 1;
}
char *serialdev = argv[1];
char *state_str = argv[2];
int state = atoi(state_str);
fd = openserial(serialdev);
if (!fd) {
fprintf(stderr, "Error while initializing %s.\n", serialdev);
return 1;
}
printf("%s: setting RS485 to ", serialdev);
if (state)
printf("%s\n", "enabled");
else
printf("%s\n", "disabled");
if (setRS485(fd, state))
return 0;
else
return 1;
}
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