The Local Interconnect Network (LIN) is an extension of the CAN data bus, exchanging digital data between actuators or sensors and the corresponding control units. One example of LIN bus application is the electric glass sunroof whose servomotor receives its commands from the comfort control unit via the LIN bus. LIN also controls the windscreen wiper and heater motor systems. Commands are only ever transmitted in one direction, from the master control unit to the downstream sensor or actuator, the 'slave'. The master can transmit commands to up to 16 downstream slaves.