Sample code

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
int main()
{
        int fd = open("/dev/ttyS1", O_RDWR);
        char test;
        if(fd<0)
        {
                printf("Error\n");
                return -1;
        }
        else
        {
                read(fd,&test,1);
        }
        close(fd);
        return 0;
}