my $rs485_port = Device::SerialPort->new("/dev/ttyUSB1");
$rs485_port->baudrate(256000) or die "die Bautrate...";
$rs485_port->parity("none"); 
$rs485_port->databits(8); 
$rs485_port->stopbits(1); 
$rs485_port->handshake("xoff"); 
$rs485_port->write_settings;
$rs485_port->stty_echo("off");
$rs485_port->lookclear; 
$rs485_port->purge_rx;
$rs485_port->write_settings;