wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

45
LIN-Bus
Andreas Grzemba
University of Applied
Sciences Deggendorf
Donal Heffernan
University of Limerick
Thomas Lindner
BMW Group
45.1 LIN Background..............................................................................45-1
45.2 LIN History and Versions..............................................................45-2
45.3 Communication Concept..............................................................45-3
45.4 Physical Layer...................................................................................45-3
Signal Specification. •. Topology
45.5 LIN Message Frames.......................................................................45-6
Break Field. •. Sync Byte Field. •. Identifier. •. Data Field. •. .
Checksum. •. Frame Length. •. Time-Triggered
Data Transmission. •. Frame Types. •. Diagnostic Frame
45.6 Network and Status Management..............................................45-10
45.7 Transport Layer Protocol............................................................. 45-11
45.8 Configuration.................................................................................45-12
45.9 Relationship between SAE J2602 and LIN2.0...........................45-12
45.10 Conclusion......................................................................................45-12
References..................................................................................................45-13
45.1 LIN Background
Modern cars contain a large number of electronic control units (ECU). For example, the BMW AG
7-series (model 2008) has over 70 ECUs and about 100 different electric motors. The car’s comfort
domain has been much improved in recent years. Comfort functions such as electric window lifters,
electric outside mirrors, central locking, air conditioning, electric seat adjustment, and an electrical
sliding roof are common features in today’s cars. In the past, when the number of features was low,
the various electrical devices were conventionally wired. However, as the number of features grew,
the wiring harness became unmanageable, and the diagnostics for such complex systems became
complex. For these reasons, the car manufacturers introduced multiplexed wired communication
systems. However, an uncontrolled growth evolved as the various manufacturers developed proprietary
protocols for in-vehicle control networks (e.g., BMW AG’s K/I-BUS, Toyota’s BEAN, GM’s
Sinebus, and E&C).
The proprietary protocols proved expensive and often had dependence on single suppliers. In an
attempt to devise a standardized solution, the car makers BMW Group, Daimler-Benz (now Daimler),
Audi, and VW, the semiconductor company Motorola (now Freescale), and the network specialist
Volcano Communications Technologies (now Mentor Graphics) founded the LIN Consortium to
develop a low-cost communications standard for the so-called Society of Automotive Engineers (SAE)
communication class A (systems up to 20.kbps) systems. The Local Interconnect Network (LIN) is a
low-cost solution, which is a universal asynchronous receiver transmitter (UART) based, single-master,
multiple-slave architecture, developed for automotive sensor and actuator applications. The LIN master
node connects the LIN network with higher level networks, usually the controller area network (CAN).
The LIN is positioned below CAN and it does not replace CAN.
45-1
© 2011 by Taylor and Francis Group, LLC