# note, ive tried ttyS0 and S1, same error with both
$port = '/dev/ttyS0';
# creates a hidden config file in user's home dir
$config = '~/.conf';

# this tests for an existing config file,
# and creates one if necessary...
if(! -e $config)
{
  $PortObj = new Device::SerialPort ($port) ||
      die(RED,"Can't open $port: $^E\n",RESET);

  $PortObj->databits(7);
  $PortObj->baudrate(19200);
  $PortObj->parity("even");
  $PortObj->stopbits(1);
  $PortObj->handshake("xoff");
  $PortObj->buffers(4096, 4096);

  $PortObj->write_settings || undef $PortObj;

  $PortObj->save("$config");

  $PortObj->close || die(RED,"failed to close",RESET);
  undef $PortObj;
}

# and this connects to the port by loading said
# config file and tying to SERIAL filehandle
$PortObj = tie (*SERIAL, 'Device::SerialPort', "$config")
              || die(RED,"Can't open $port: $^E\n",RESET);

# use non-blocking read on serial port
$PortObj->read_char_time(5);
$PortObj->read_const_time(500);

# create flag variables initialized to zero...
my $EXIT = 0;
# ...when a trapped system signal is sent, set flag to 1
$SIG{'INT'} = sub { $EXIT = 1 };