Page 289 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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272 Automobile mechanical and electrical systems

Figure 3.29 Wiring harness

Bus 1 Drive train bus
Bus 1 e.g. Motronic
ABS/ASR/ESP
Transmission control

Bus 2 Multimedia bus
e.g. Main display unit
Radio
Bus 2
Travelpilot
Bus 3 Body bus
e.g. Parkpilot

Body computer
Bus 3
Door control units

Figure 3.30 Controller area network (CAN) system for instrumentation. (Source: Bosch Media)

system. To illustrate the operation of this system, consider the events involved
in switching the sidelights on and off. First, in response to the driver pressing
Key fact the light switch, a unique signal is placed on the data bus. This signal is only
A data bus can carry information recognized by special receivers built as part of each light unit assembly, which
from sensors and allows ECUs to in turn will make a connection between the power supply cable and the lights.
communicate with each other. The events are similar in turning off the lights, except that the code placed on the
data bus will be different and will be recognized only by the appropriate receivers
as an off code. A data bus can also carry information from sensors and allows
electronic control units (ECUs) to communicate with each other.
Bosch has developed a data bus protocol known the controller area network
(CAN) ( Fig. 3.30 ). CAN is suitable for transmitting data in the area of driveline
components, chassis components and mobile communications. It is a compact
system, which will make it practical for use in many areas. Two variations on the
physical layer are available which suit different transmission rates. One variation