Editing Local Interconnect Network (section)

== LIN message frame ==
A message contains the following fields:<ref name="SPEC" />

* Synchronization break
* Synchronization byte
* Identifier byte
* Data bytes
* Checksum byte

=== Frame types ===
# ''' Unconditional frame. ''' These always carry signals and their identifiers are in the range 0 to 59 (0x00 to 0x3b). All subscribers of the unconditional frame shall receive the frame and make it available to the application (assuming no errors were detected).
# '''Event-triggered frame.''' The purpose of this is to increase the responsiveness of the LIN cluster without assigning too much of the bus bandwidth to the polling of multiple slave nodes with seldom occurring events. The first data byte of the carried unconditional frame shall be equal to a protected identifier assigned to an event-triggered frame. A slave shall reply with an associated unconditional frame only if its data value has changed. If none of the slave tasks responds to the header the rest of the frame slot is silent and the header is ignored. If more than one slave task responds to the header in the same frame slot a collision will occur, and the master has to resolve the collision by requesting all associated unconditional frames before requesting the event-triggered frame again.
# ''' Sporadic frame.''' This frame is transmitted by the master as required, so a collision cannot occur. The header of a sporadic frame shall only be sent in its associated frame slot when the master task knows that a signal carried in the frame has been updated. The publisher of the sporadic frame shall always provide the response to the header.
# '''Diagnostic frame.''' These always carry diagnostic or configuration data and they always contain eight data bytes. The identifier is either 60 (0x3C), called master request frame, or 61(0x3D), called slave response frame. Before generating the header of a diagnostic frame, the master task asks its diagnostic module if it shall be sent or if the bus shall be silent. The slave tasks publish and subscribe to the response according to their diagnostic module.
# '''User-defined frame.''' These can carry any kind of information. Their identifier is 62 (0x3E). The header of a user-defined frame is always transmitted when a frame slot allocated to the frame is processed
# '''Reserved frame.''' These shall not be used in a LIN 2.0 cluster. Their identifier is 63 (0x3F).