Mercedes-Benz 212 Sedan E-Class Service Manual page 74

Introduction
The ever increasing demands on the on-board elec-
tronic system in the fields of vehicle safety, comfort,
communications and diagnosis require wider and
wider networking of the existing systems in order to
allow the necessary information to be exchanged. To
provide complete vehicle networking, a number of
control units also function as gateways, i.e. data from
the connected bus systems are relayed by these
control units.
The following data bus systems are used to exchange
the necessary information:
• Controller Area Network (CAN)
• Media Oriented System Transport (MOST)
CAN
The CAN is an electrical bus system that transmits
data over two lines.
Each connected control unit can send or receive data
(bidirectional bus). A data protocol defines the indi-
vidual data blocks and specifies which data can be
received or transmitted by a control unit. Any errors
detected are saved and stored in the fault memory.
The following CAN buses are involved in the overall
network:
Telematics CAN (CAN A)
The telematics CAN is responsible for data transfer by
the telecommunications systems.
Transfer rate 125 kbit / s.
– This printout will not be recorded by the update service. Status: 01 / 2009 –
Interior CAN (CAN B)
The interior CAN is responsible for data transfer in the
vehicle interior.
Transfer rate 125 kbit / s.
Drivetrain CAN (CAN C)
The drivetrain CAN is responsible for data transfer by
the drive systems.
Transfer rate 500 kbit / s.
Diagnostic CAN (CAN D)
The data link connector cab be used to connect an
external tester (e.g. Xentry Diagnostics) to the diag-
nostic CAN.
Transfer rate 500 kbit / s.
Chassis CAN (CAN E)
The chassis CAN is responsible for data transfer by the
chassis and suspension systems.
Transfer rate 500 kbit / s.
Front end CAN (CAN G)
The front end CAN is responsible for data transfer by
the front light systems in vehicles with xenon head-
lamps.
Transfer rate 500 kbit / s.
Vehicle dynamics CAN (CAN H)
The vehicle dynamics CAN is responsible for data
transfer of the vehicle dynamic data, e.g. the turn rate
or longitudinal acceleration.
Transfer rate 500 kbit / s.
Drivetrain sensor CAN (CAN I)
The drivetrain sensor CAN is responsible for data
transfer at the exhaust system.
Transfer rate 500 kbit / s.
Introduction of the New E-Class, Model Series 212 Sedan
Overall network
b
73