This should get you started. It's a script I use to read my weather station. And, it will run either *nix, or Win32 platforms.

#!/usr/bin/perl -w

#
#  What we use
#
use strict;
require 5.005;
use vars qw($OS_win);

my $debugGlobal = 0;
my $portName = 0;
my $logPath = 0;

#
#  Run early to determine whether to load Win32::SerialPort (Win32) or
+ Device::SerialPort (Linux)
#
BEGIN 
{
   $OS_win = ($^O eq "MSWin32") ? 1 : 0;
   
   # print "Perl version: $]\n";
   # print "OS   version: $^O\n";
   
   #
   # This must be in a BEGIN in order for the 'use' to be conditional
   #
   if ($OS_win) 
   {
      eval "use Win32::SerialPort 0.14";
      die "$@\n" if ($@);
   }
   else 
   {
      eval "use Device::SerialPort";
      die "$@\n" if ($@);
   }
}

#
#  Main entry point.  If "action" is not defined, we default to login.
#
{
   my $data = 0;

   #
   #  Enable flushing, && if debugging, kick out the content type
   #
   $| = 1;
   
   if (OS_Linux ())
   {
      $logPath = "/home/system/weather/runlog.log";
      $portName = '/dev/ttyS0';
   }
   else
   {
      $logPath = "c:/perl/scripts/weather/runlog.log";
      $portName = 'COM1';
   }

   $debugGlobal && (open (LOG, ">>$logPath") || die "runlog.log: $!");
   $debugGlobal && LOG->autoflush (1);

   runlog ('Starting run');

   $data = read_wx_station ();

   runlog ("Exiting...\n");

   exit;
}

#
#  Return 0 if running Windows, 1 if running anything else (Linux)
#
sub OS_Linux
{
   return ($^O eq 'MSWin32' ? 0 : 1);
}

#
#
#
sub read_wx_station
{
   my $ob = 0;
   my $c = 0;
   my $record = "";
   my $errcnt = 0;
   my $totalinbytes = 0;
   my $starttime = 0;

   if (OS_Linux ())
   {
      $ob = new Device::SerialPort ($portName, 1);
   }
   else
   {
      $ob = new Win32::SerialPort ($portName, 1);
   }

   runlog ("Can't open serial port $portName: $^E\n") unless ($ob);
   die unless ($ob);

   runlog ('Setting serial port conditions');

   $ob->baudrate (2400);
   $ob->parity ('none');
   $ob->databits (8);
   $ob->stopbits (1);
   $ob->handshake ('none');
   $ob->stty_icrnl (1);
   $ob->stty_ocrnl (1);
   $ob->stty_onlcr (1);
   $ob->stty_opost (1);
   $ob->write_settings ();

   runlog ('Waiting for a full weather record');

   $starttime = time;

   for (;;) 
   {
      my $blockingflags = 0;
      my $inbytes = 0;
      my $outbytes = 0;
      my $errflags = 0;

      #
      #  See if we can read anything from the port
      #
      ($blockingflags, $inbytes, $outbytes, $errflags) = $ob->status o
+r warn "could not get port status\n";

      #
      #  Did we get an 8250 error?
      #
      if (!OS_Linux ()) 
      {
         if ($errflags & ($ob->CE_RXOVER | $ob->CE_OVERRUN | $ob->CE_R
+XPARITY | $ob->CE_FRAME))
         {
            if ($errcnt++ == 10)
            {
               runlog ("Aborted due to more than 10 errors\n");
               die;
            }
   
            runlog ('Purging port');
            $ob->purge_rx;
            $record = "";
         }
      }

      #
      #  Add the number of bytes read to the running total.  Die if to
+o many bytes without a record.  Just for
      #  grins, if we get too many, try shifting the baud rate and set
+ting back so the UART will re-sync.
      #
      $totalinbytes += $inbytes;

      if ($totalinbytes > 1000)
      {
         if ($errcnt++ == 3)
         {
            runlog ("1000+ bytes read with no good data (wrong mode?)\
+n");
            runlog ($record);
            die;
         }
         else
         {
            runlog ("purge for 1000+ bytes read with no good data");
            $ob->baudrate (4800);
            $ob->write_settings ();
            $ob->baudrate (2400);
            $ob->write_settings ();
            $totalinbytes = 0;
            $starttime = time;
         }
      }

      #
      #  If input is present in the buffer, read it, and add it to our
+ cumulative string
      #
      if ($c = $ob->input) 
      {
         $c =~ s/\r//g;    
         $c =~ s/\n//g;    
         $record .= $c;

         if ($record =~ m/(!!)/)
         {
            runlog ("U2000 is in datalogging mode!\n");
            die;
         }
         elsif ($record =~ m/(\$ULTW)/i)
         {
            runlog ("U2000 is in packet mode!\n");
            die;
         }

         last if $record =~ /(&CR&).*(&CR&)/;
      }
        
      #
      #  See if we've been doing this serial thing for too long.
      #
      if ((time - $starttime) > 30)
      {
         runlog ("Over 30 seconds with no good data (U2000 connected?)
+\n");
         die;
      }

      #
      #  Basically sleep for .2 seconds
      #
      select undef, undef, undef, 0.2;
   }

   runlog ('Port read complete');

   $ob->close or die "Close failed: $!\n";
   undef $ob;

   runlog ('Starting weather data parsing');

   $record =~ s/^.*?(&CR&)//;
   $record =~ s/(&CR&).*//;
   $record =~ s/^/&CR&/;

   runlog ('Returning 1 complete weather record');

   return ($record);
}

#
#
#
sub runlog
{
   my $text = shift;

   $debugGlobal && print LOG scalar (localtime ()), ": $text\n";
}
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--Chris

e-mail jcwren