my $PortObj;
if ( $^O =~ m/Win32/ ) {
     require Win32::SerialPort;
     $PortObj = new Win32::SerialPort ($PortName, $quiet, $lockfile)
         or die "Can't open $PortName: $!\n";
}
else {
    require Device::SerialPort;
    $PortObj = new Device::SerialPort ($PortName, $quiet, $lockfile)
        or die "Can't open $PortName: $!\n";
}

# theoretically do same stuff on Win32 or Linux with same method calls