def get_fp_version(self):
        """
        :return: the fingerprint version
        """
        command = const.CMD_OPTIONS_RRQ
        command_string = b'~ZKFPVersion\x00'
        response_size = 1024

        cmd_response = self.__send_command(command, command_string, response_size)
        if cmd_response.get('status'):
            response = self.__data.split(b'=', 1)[-1].split(b'\x00')[0]
            response = response.replace(b'=', b'')
            return safe_cast(response, int, 0) if response else 0
        else:
            raise ZKErrorResponse("can't read fingerprint version")