$TTY = "/dev/ttyS0";

$STTY ="ignbrk -icrnl -ixon -opost -onlcr -isig -icanon -iexten parenb -parodd cs8 -echo -echoe"
        ." -echok -echoctl -echoke min 0 time 5 1200";

`stty $STTY <$TTY`;

open(IN,"$TTY") || die "\ncan not open Interface for reading $!\n";
open(OUT,">$TTY") || die "\ncan not open Interface for writeing $!\n";

$oldfh = select(OUT);
$| = 1;
select($oldfh);
$| = 1;