So you need two barcodes to sit side by side. '0' and '1'. You can create them with this code:

#!/usr/bin/perl
use strict;
use warnings;
use GD::Barcode::Code39;
MakeBar('0');
MakeBar('1');
sub MakeBar {
  my $txt = shift;
  my $oGdBar = GD::Barcode::Code39->new("*$txt*");
  die $GD::Barcode::Code39::errStr unless($oGdBar);
  open(IMG, ">", "$txt.png") or die $!;
  binmode(IMG);
  print IMG $oGdBar->plot(NoText=>1, Height => 40)->png;
  close(IMG);
}
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Then print and affix them to your door. I haven't tested the following code because I have hacked my cuecat to decode the scans but you could use something like this:

#!/usr/bin/perl
use strict;
use warnings;
use Barcode::Cuecat;
# seperate counters for open and closed
my $open = 0;
my $close = 0;
my $door;
my $bc = new Barcode::Cuecat();
while (<>) {
    $bc->scan($_);
    $door .= $bc->code();
    if (length $door == 2) {
      $open++ if ($door eq "01");
      $close++ if ($door eq "10");
      $door = "";
      # we will assume the door started out closed
      my $state = "closed";
      $state = "open" if ($open > $closed);
      print "Opened: $open times\n";
      print "Closed: $closed times\n";
      print "Current state: $state\n";
      # write to disk
    }
}
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