C/Visual C - Leer del puerto con RS485

#include <sys/ioctl.h>

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <asm/ioctls.h>

#include <errno.h>

#include <termios.h>

/* RS485 ioctls: */

#define TIOCGRS485 0x542E

#define TIOCSRS485 0x542F

// Control struct for setting the port in 485 mode

struct rs485_ctrl {

unsigned short rts_on_send;

unsigned short rts_after_sent;

unsigned int delay_rts_before_send;

unsigned short enabled;

};

// his struct is only needed if we would like to write with ioctl()

struct rs485_wrt {

unsigned short outc_size;

unsigned char *outc;

};

int main(void) {

char dev[] = "/dev/ttySC0";

// char buffer_to_send[] = { 0x55, 0x00, 0x55 };

char buffer_to_send[11] = "HELLO WORLD";

char buffer_to_recv[100] = "";

int baudrate = B9600;

struct rs485_ctrl ctrl485;

int status;

int fd;

struct termios ti;

struct termios ti_prev;

// Open the serial port

fd = open(dev, O_RDWR|O_NONBLOCK);

if (fd < 0) {

printf("ERROR! Failed to open %s\n", dev);

return -1;

}

// Set the serial port in 485 mode

ctrl485.rts_on_send = 0; // It means that DE is at 3.3 volt on send

ctrl485.rts_after_sent = 1; // It means that DE is at 0 volt on send

ctrl485.delay_rts_before_send = 0; // DE will be active at same time of data

ctrl485.enabled = 1;

// status = ioctl(fd, TIOCSERSETRS485, &ctrl485);

status = ioctl(fd, TIOCSRS485, &ctrl485);

if (status) {

// printf("ERROR PORT 1! TIOCSERSETRS485 failed %i", status);

printf("ERROR PORT 1! TIOCSRS485 failed %i", status);

return -1;

}

tcgetattr(fd, &ti_prev); // Save the previous serial config

tcgetattr(fd, &ti); // Read the previous serial config

cfsetospeed(&ti,baudrate); // Set the TX baud rate

cfsetispeed(&ti,baudrate); // Set the RX baud rate

cfmakeraw(&ti);

tcsetattr(fd, TCSANOW, &ti); // Set the new serial config

// Send buffer_to_send content to RS485

if (write(fd, buffer_to_send, sizeof(buffer_to_send)) != sizeof(buffer_to_send)) {

printf("ERROR! write() failed \r\n");

}

// Read a char

int Lcl_Cant = read(fd,&buffer_to_recv,1);

printf("Lcl_Cant: [%d]\n", Lcl_Cant);

// perror( error );

if ( Lcl_Cant == 1) {

printf("%c",buffer_to_recv[0]);

printf("\n");

}

else {

perror("ERROR: !");

printf("errno = %d.\n", errno);

}

ti_prev.c_cflag &= ~HUPCL; // This to release the RTS after close

tcsetattr(fd, TCSANOW, &ti_prev); // Restore the previous serial config

close(fd);

return 0;

}