串口c编程接收数据

Question

我正在使用简单的c程序从传感器接收数据，该传感器通过UART发送数据。在Ubuntu工作。程序简单如下所示：

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>

#include <stdlib.h>

#include<arpa/inet.h>
#include<sys/socket.h>
#include <net/if.h>
#include <unistd.h>
#include <sys/ioctl.h>

#define BAUDRATE B9600   // Change as needed, keep B
#define MODEMDEVICE "/dev/ttyS0" 
#define _POSIX_SOURCE 1 /* POSIX compliant source */

#define FALSE 0
#define TRUE 1

main()
{
    int fd, c, res;
    char buf[1024];
    struct termios oldtio, newtio;

    fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd < 0) 
    { 
    perror(MODEMDEVICE); 
    exit(-1); 
    }

    bzero(&newtio, sizeof(newtio)); /* clear struct for new port settings */


    newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;


    newtio.c_iflag = IGNPAR;

    /*  Raw output  */
    newtio.c_oflag = 0;


    newtio.c_lflag = ICANON;
    /* now clean the modem line and activate the settings for the port */
    tcflush(fd, TCIFLUSH);
    tcsetattr(fd,TCSANOW,&newtio);

    while (TRUE) {     /* loop continuously */

        memset(buf,0,1024);

        res = read(fd, buf, 1024);
        buf[res] = 0;             /* set end of string, so we can printf */
        printf("%s\n", buf);

    }
    tcsetattr(fd, TCSANOW, &oldtio);
}

这个程序正在运行，但它会收到一些数据，如：

abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789
abcdef,234.456,678.234,w,e,123.5566,78.90,12344.567,3456.789

继续循环5-8次后，它没有接收数据。程序不退出（它只会处于运行状态），但数据不会打印。

如何让这个程序连续接收数据......（无限次）