public function getCode128CheckNum($val)
    {
        $sum = 103;
        for ($i = 0; $i < strlen($val); $i++) {
            $sum += ($i + 1) * $this->ChrToC128(ord(substr($val, $i, 1)));
        }

        $ch_num = $sum % 103;

        return $ch_num;
    }