#include <stdio.h>   /* Standard input/output definitions */
    #include <string.h>  /* String function definitions */
    #include <unistd.h>  /* UNIX standard function definitions */
    #include <fcntl.h>   /* File control definitions */
    #include <errno.h>   /* Error number definitions */
    #include <termios.h> /* POSIX terminal control definitions */

    /*
 *      * 'open_port()' - Open serial port 1.
 *           *
 *                * Returns the file descriptor on success or -1 on error.
 *                     */

    int
    open_port(void)
    {
      int fd; /* File descriptor for the port */


      fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
      if (fd == -1)
      {
       /*
 * 	* Could not open the port.
 * 		*/

	perror("open_port: Unable to open /dev/ttyUSB0 - ");
      }
      else
	fcntl(fd, F_SETFL, 0);

      return (fd);
    }

/*n = write(fd, "ATZ\r", 4);
    if (n < 0)
      fputs("write() of 4 bytes failed!\n", stderr);
*/

fcntl(fd, F_SETFL, FNDELAY);


/* put our read code here */


fcntl(fd, F_SETFL, FNDELAY);

close(fd);