code: def set_crc(self):
          
          data = self.bytes[6:20]
          crc = int(0)
          for b in data:
              # pylint: disable=unused-variable
              for bit in range(0, 8):
                  fb = b & 0x01
                  fb = fb ^ 0x01 if (crc & 0x8000) else fb
                  fb = fb ^ 0x01 if (crc & 0x4000) else fb
                  fb = fb ^ 0x01 if (crc & 0x1000) else fb
                  fb = fb ^ 0x01 if (crc & 0x0008) else fb
                  crc = ((crc << 1) | fb) & 0xffff
                  b = b >> 1
          self._userdata['d13'] = (crc >> 8) & 0xff
          self._userdata['d14'] = crc & 0xff
docs: Set Userdata[13] and Userdata[14] to the CRC value.