Because the communication in a LIN cluster is based on the delegated token principle, the LIN master must initiate and delegate the communication in a LIN cluster. The LIN master fulfills this requirement by transmitting a clearly identifiable frame header at the beginning of each frame slot in the framework of cyclic processing of the LIN schedule (exception: sporadic frame). The frame header is supplemented by the frame response from one of the slave tasks listed in the LDF (in the case of an event-triggered frame the response may also be lacking).

The resulting LIN frame is referred to as an unconditional frame. The unconditional frame is the frame type that a system designer uses for periodic transmission of user data. Next to unconditional frames, so-called event-triggered frames, sporadic frames and diagnostic frames are also available to the system designer. You can use the interactive figure “Frame Types” to explore key properties of the individual frame types.

The event-triggered frame is used to communicate sporadic changes or events on the part of the LIN slaves. It is essentially an unconditional frame, the only difference being that multiple frame responses from different LIN slaves are assigned to one frame header.

A sporadic frame is understood as an unconditional frame that shares the same frame slot with other unconditional frames. Sporadic frames are transmitted by the LIN master completely, but only when necessary. When there is no need for a sporadic frame, its frame slot remains empty. Diagnostic frames are used to configure and diagnose LIN slaves using a standardized transport protocol (ISO 15765-2) and uniform diagnostic services (ISO 15765-3).