UART auslesen funktioniert nicht

 #include <stdio.h>

 #include <fcntl.h>   /* File Control Definitions           */

 #include <termios.h> /* POSIX Terminal Control Definitions */

 #include <unistd.h>  /* UNIX Standard Definitions      */ 

 #include <errno.h>   /* ERROR Number Definitions           */

 void main(void)

 {

     int fd;/*File Descriptor*/

     fd = open ("/dev/ttyUSB1", 'r'); //fd = open("/dev/ttyUSB1",O_RDWR | O_NOCTTY);  

     if(fd == -1)            /* Error Checking */

       printf("\n  Error! in Opening ttyUSB1  ");

     else

       printf("\n  ttyUSB1 Opened Successfully ");

     struct termios SerialPortSettings;  /* Create the structure                          */

     tcgetattr(fd, &SerialPortSettings);  /* Get the current attributes of the Serial port */

     /* Setting the Baud rate */

     cfsetispeed(&SerialPortSettings,B115200); /* Set Read  Speed as 115200                       */

     cfsetospeed(&SerialPortSettings,B115200); /* Set Write Speed as 115200                       */

    /* 8N1 Mode */

    SerialPortSettings.c_cflag &= ~PARENB;   /* Disables the Parity Enable bit(PARENB),So No Parity   */

    SerialPortSettings.c_cflag &= ~CSTOPB;   /* CSTOPB = 2 Stop bits,here it is cleared so 1 Stop bit */

    SerialPortSettings.c_cflag &= ~CSIZE;   /* Clears the mask for setting the data size             */

    SerialPortSettings.c_cflag |=  CS8;      /* Set the data bits = 8                                 */

    SerialPortSettings.c_cflag &= ~CRTSCTS;       /* No Hardware flow Control                         */

    SerialPortSettings.c_cflag |= CREAD | CLOCAL; /* Enable receiver,Ignore Modem Control lines       */ 

    SerialPortSettings.c_iflag &= ~(IXON | IXOFF | IXANY);          /* Disable XON/XOFF flow control both i/p and o/p */

    SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG);  /* Non Cannonical mode                            */

    SerialPortSettings.c_oflag &= ~OPOST;/*No Output Processing*/

    /* Setting Time outs */

    SerialPortSettings.c_cc[VMIN] = 10; /* Read at least 10 characters */

    SerialPortSettings.c_cc[VTIME] = 0; /* Wait indefinetly   */

    if((tcsetattr(fd,TCSANOW,&SerialPortSettings)) != 0) /* Set the attributes to the termios structure*/

        printf("\n  ERROR ! in Setting attributes");

    else

                    printf("\n  BaudRate = 115200 \n  StopBits = 1 \n  Parity   = none");

          /*------------------------------- Read data from serial port -----------------------------*/

    tcflush(fd, TCIFLUSH);   /* Discards old data in the rx buffer            */

    char read_buffer[32];   /* Buffer to store the data received              */

    int  bytes_read = 0;    /* Number of bytes read by the read() system call */

     int i = 0;

    bytes_read = read(fd,&read_buffer,32); /* Read the data                   */

    printf("\n\n  Bytes Rxed -%d", bytes_read); /* Print the number of bytes read */

    printf("\n\n  ");

    for(i=0;i<bytes_read;i++)   /*printing only the received characters*/

        printf("%c",read_buffer[i]);

    printf("\n +----------------------------------+\n\n\n");

    close(fd); /* Close the serial port */

}