Within a LIN cluster, nodes are signal based interaction layers to allow the Application SW to access the LIN physical layer.
Inside this interface, it is also attached a “Transport layer” which is the responsible to define the transportation of one or more frames (Single Frame or Multiple Frames). The transport layer is between the Physical Frame Handling and the Application.
A LIN Cluster always has a Master Node and one or more Slave Nodes. A Master Node contains two types of Task: A Master Task and a Slave Task; whereas Slave Nodes only can contain Slave Tasks.
- Master Task: Decide the transference flow of the nodes within the LIN bus.
- Slave Task: Provide the data required for each frame.
Therefore, the Master Node ask for each slave node to provide data while parallelly, it is also providing data from its own node (when Slave requires information to respond).
A frame consists of a header and a response. The header is provided only by the Master task whereas the response is provided only by the slave task.
- Header consists mainly of a break file, synch field and a frame ID.
- The slave response consists mainly of a data field and a check sum.
There are two types of data that can be transported within a frame:
- Diagnostic Message Composed by two reserved frame ID bytes with a data field. Diagnostic message can trigger different kind of behaviors to the receiving node; this depend of the receiving node communication status, whether it is under normal communication state or any special state as DV mode, extended session and so on.
- Signals, Signals can be scalar values or array of scalar values that always have the same sort within the frame.
The schedule table is the instance which specify the transmitting of header specifying the order and timing of those. The master Application SW can define different schedules and the transitions among them.