Communication over the LIN bus is controlled entirely by the master task in the master device. The basic unit of transfer on the LIN bus is the frame, which is divided into a header and a response. The header is always transmitted by the master node and consists of three distinct fields: the break, synchronization (sync), and identifier (ID). The response, which is transmitted by a slave task and can reside in either the master node or a slave node, consists of a data payload and a checksum.[12][13]