Overview
This document contains the following information:
General
Bus systems
CAN bus
Chassis FlexRay
MOST
Ethernet
Ethernet vehicle access via diagnostics connection
General
The requirements placed on vehicle electronics, e.g. in the following areas, increase continuously:
Vehicle safety
Comfort
Communication
Diagnosis
The existing systems must be networked in the vehicle so that the necessary information can be exchanged.
This cannot be realized with a conventional data transfer because the installation space is limited and a reduction of the vehicle weight is sought. This is why bus systems are used.
Bus systems
Bus systems are networks for transferring information and signals between control units, sensors, actuators and peripheral devices. Bus systems usually operate hierarchically in such a way that one or more sub-buses, e.g. a LIN bus, are subordinate to a superordinate bus, for example the CAN bus.
Various bus systems are applied in the vehicle. The individual bus systems form a common network through control units with gateway functions. In this way, the data provided are made available to all participating systems.
CAN bus
The CAN is an electric bus system for the transmission of data through 2 lines.
The CAN consists of a twisted, two-core data line that connects all CAN subscribers together in a parallel circuit.
Both lines of the data line must not be swapped because of the differing signal levels.
Each connected control unit is able to transmit or receive data (bidirectional bus). The data is sent digitally via the CAN at various intervals. The individual data blocks are defined in a data protocol and it is specified which data are received or transmitted by a control unit.
The sum of the data blocks, the short break between 2 transfer intervals and other properties of the CAN are checked constantly. Detected faults are stored and placed in the fault memory.
The CAN offers the following advantages:
Fast data exchange between individual control units
Sensor signals are available for many systems
The number of electric lines is reduced
The electromagnetic compatibility is improved
Chassis FlexRay
The chassis FlexRay is a quick, deterministic and fault-tolerant bus system. Signals are not transmitted based on an event but during fixed defined time windows. As a result, the bus load can be reduced. The time windows are divided into static and dynamic sections.
In order to improve the interference resistance, the suspension FlexRay consists of a twisted two-core data line. Each connected control unit is able to transmit or receive data.
MOST
MOST is, depending on the model, an optical or an electrical bus system.
The data is transmitted either optically via fiber-optic cables or electrically via coaxial conductors to the connected information, navigation and communication components.
Ethernet
Ethernet is used for data transfer at particularly high bandwidth; for example when processing video images in real time.
Ethernet operates at a data transfer rate of 100 Mbit/s.
In order to provide sufficient interference resistance, the Ethernet lines consist of twisted strands. Each connected control unit is identified using its MAC address and can simultaneously send and receive data.
Ethernet vehicle access via diagnostics connection
The Ethernet vehicle access is used for data transfer to the head unit. The Ethernet vehicle access operates with a data rate of 100 Mbit/s.
The bandwidth of 100 Mbit/s makes it possible to program the Digital Owner's Manual, the head unit and the MOST components, for example, without a separate DVD.
Referenced documents
- gf0019p002001a Overall network (GVN), detailed information
- gf0019p002001b Overall network (GVN), detailed information
- gf0019p002001c Overall network (GVN), detailed information
- gf0019p002001d Overall network (GVN), detailed information
- gf0019p002001e Overall network (GVN), detailed information
- gf0019p002001f
- gf0019p002001g Overall network (GVN), detailed information
- gf0019p002001h Overall network (GVN), detailed information
- gf0019p002001i Overall network (GVN), detailed information
- gf0019p002001j Overall network (GVN), detailed information