rharsh, please take a look at my mod on your code, I used the xor to compute 2's complement.
Thanks again for your effort.
my $str = '1000F000FF3FFF3FFF3FFF3FFF3FFF3FFF3FFF3F10';
my $check = substr($str,length($str)-2,2, ""); #Strip Checksum
my $sum;
$sum += $_ for unpack('C*', pack("H*"...