#!/usr/bin/perl
use strict;
use warnings;

my @send= fillbuffer();

my $buf=pack('s*',@send);
my $len=@send;
print "<$buf> <$len>";
#  $ok=$client_socket->syswrite($buf,$len); 

sub fillbuffer { return ( STX(),0x11,0x12,ETX() ); }
sub STX() { "\002" };
sub ETX() { "\003" };