use Device::SerialPort;
my $query = new CGI;

my $port = new Device::SerialPort("/dev/ttyUSB0");
$port->baudrate(9600);
$port->parity("none"); 
$port->databits(8); 
$port->stopbits(1); 
$port->handshake("xoff"); 
$port->write_settings;
$port->stty_echo("off");
$port->lookclear; 
$port->purge_rx;
$port->write($query->param('befehl'));
$port->write(";");