I wonder if UTF-8 is automatically selected as I don't turn it on at all. Here's the full code.

#!/usr/bin/perl -w

use strict;
use LWP;
use Getopt::Long;

##
## GLobal variables
##
my $primary_server = "";
my $timeout = 30;    # No. of seconds to wait for request to timeout
my $uagent;          # User Agent object
my $line;            # A Line read from the order file
my $mtid;            # First 4 digits of the input line
my $bits;            # Bit flags (64 or 128, first bit of 1 = 128)
my $bitsize;         # The length of bit flags (either 64 or 128)
my $byte;            # eight bit flags.
my $data;            # The data
my $reqsize;         # The length of the fully packed request.
my $request;         # Holds the full request line converted to binary
my $cmd_line;        # Holds the xml command to submit
my $reply;           # Holds raw reply from server
my $error_flag;      # Err flag (0=no error, 1=timeout, 2=failed)
my $i;               # counter
my $dummy;


############################################################
## MAIN main MAIN main MAIN main MAIN main MAIN main MAIN ##
############################################################
#
# Read.
#
#$primary_server = <STDIN>;
#$primary_server =~ s/\n//;

#
# Read the input line from STDIN.
#
$line = <STDIN>;
$line =~ s/\n//;

$mtid = substr( $line, 0, 4 );
$reqsize = 4;
$bits = substr( $line, 4, 1 );
if ($bits eq "1")
{
    $bitsize = 128;
    $reqsize += 16;
}
else
{
    $bitsize = 64;
    $reqsize += 8;
}
$bits = substr( $line, 4, $bitsize );
$data = substr( $line, 4 + $bitsize );
$reqsize += length( $data );

$request = pack( "n", $reqsize );
$request .= $mtid;
$request .= pack( 'B*', $bits );

$request .= $data;

print STDOUT $request;
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Note that this is still a work in progress and several pieces - including the communications and response - have not been coded, yet. I'm just trying to see if I can get this to work for building binary data.