I'm trying to write a char array to the serial port twice. For some reason the second time I call write() it fails and I have no idea why. The weird part is that the first write succeeds.

Here's my write function:

```
void write_port()
{
  unsigned char writeBuffer[5];
  int i;
  size_t len;

  writeBuffer[0] = 0x00;
  writeBuffer[1] = 0x01;
  writeBuffer[2] = 0x02;
  writeBuffer[3] = 0x03;
  writeBuffer[4] = 0x04;  

  len = sizeof(writeBuffer);

  for (i=0; i < len; i++)
  {
    printf("Write: %x\n", writeBuffer[i]);
  }

  //First Write:
  int n = write(fd, writeBuffer, len);
  if (n < 0)
    fputs("Serial Port Write Failed!\n", stderr);
  else
    printf("Wrote %0d bytes to serial port\n", n);

  //Second Write:
  n = write(fd, writeBuffer, len);
  if (n < 0)
    fputs("Serial Port Write Failed!\n", stderr);
  else
    printf("Wrote %0d bytes to serial port\n", n);  
}

```

Here's where I configure the port:

```
int open_port(void)
{
  struct termios options;

  fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY | O_NONBLOCK);

  bzero(&options, sizeof(options));   // set everything to 0 

  if (fd != -1)
  {
    printf("Serial Port Open\n");

    tcgetattr(fd, &options_original);
    tcgetattr(fd, &options);
    cfsetispeed(&options, B460800);
    cfsetospeed(&options, B460800);
    options.c_cflag |= (CLOCAL | CREAD); /* Enable the receiver and set local mode */
    options.c_cflag &= ~ECHO; // Disable echoing of input characters
    options.c_cflag &= ~ECHOE;
    options.c_cflag &= ~PARENB; // parity disabled
    options.c_cflag &= ~CSTOPB; // 1 stop bit
    options.c_cflag &= ~CSIZE;  // Mask the character size bits
    options.c_cflag |=  CS8;    // 8 data bits    
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);  /* Raw Input Mode */

    if (tcsetattr(fd, TCSANOW, &options))    /* Set the new options for the port */
    {
      perror("could not set the serial settings!");
      return -1;
    }
  }
  else
  {
    /* Could not open the port */
    perror("open_port: Unable to open /dev/ttyUSB0 - ");
  }

  return (fd);
}

```

Finally here's my console output.

```
Serial Port Open
Flushing IO Buffers
Write: 0
Write: 1
Write: 2
Write: 3
Write: 4
Wrote 5 bytes to serial port
Serial Port Write Failed!
Serial Port Closed

```

So for some unknown reason I get -1 back from the second write() and have absolutely no idea why, what in the world could cause that?