D-Can; Ethernet; Most - BMW F48 Technical Training Manual

F48￿General￿Vehicle￿Electronics
1.￿Vehicle￿Electrical￿System
The￿CAN￿bus￿system￿is￿an￿event-controlled￿bus￿system.￿Data￿is￿transmitted￿when￿an￿event￿occurs.
As￿these￿events￿have￿different￿priorities￿(e.g.￿ambient￿temperature￿has￿a￿lower￿priority￿than￿a￿DSC
intervention,￿for￿example),￿the￿priorities￿are￿also￿sent￿in￿the￿bus￿message.￿The￿message￿with￿the
higher￿priority￿is￿sent￿first.￿As￿the￿control￿unit￿still￿wants￿to￿send￿the￿message￿which￿has￿the￿lower
priority,￿it￿frequently￿results￿in￿overloading￿in￿the￿bus￿systems.
The￿FlexRay￿works￿with￿so-called￿"time￿slots".￿With￿this￿method￿the￿messages￿are￿sent￿and￿are￿not
controlled￿by￿events,￿but￿each￿control￿unit￿in￿the￿FlexRay￿network￿is￿assigned￿a￿fixed￿time￿slot￿in￿which
it￿sends￿its￿message￿within￿a￿certain￿period.￿This￿time￿slot￿is￿synchronised￿with￿every￿restart￿of￿the
data￿bus.￿The￿control￿units￿which￿synchronize￿the￿FlexRay￿are￿always￿labelled￿in￿the￿bus￿diagram￿with
a￿"S"￿(see￿chapter￿1.1).
The￿FlexRay￿can￿also￿be￿synchronised￿with￿the￿BMW￿diagnosis￿system￿in￿the￿event￿of￿a￿fault￿and
corresponding￿fault￿code.
1.2.4.￿D-CAN
The￿D-CAN￿for￿the￿vehicle￿diagnosis￿has￿a￿data￿transfer￿rate￿of￿500￿kBit/s.
1.2.5.￿Ethernet
The￿Ethernet￿access￿is￿used￿for￿programming￿the￿entire￿vehicle.
In￿a￿F48￿with￿navigation￿system￿the￿map￿update￿for￿the￿navigation￿can￿also￿be￿effected￿using￿the
Ethernet￿interface.
1.2.6.￿MOST
In￿the￿F48￿the￿Media￿Oriented￿System￿Transport￿(MOST)￿bus￿works￿at￿a￿data￿transfer￿rate￿of
22.5 MBit/s.
1.3.￿Sub-bus￿systems
1.3.1.￿Local￿interconnect￿network￿bus
Different￿data￿rates￿are￿used￿for￿the￿local￿interconnect￿network￿bus￿according￿to￿the￿information
required.￿The￿data￿transfer￿rates￿of￿the￿local￿interconnect￿network￿bus￿in￿the￿F48￿range￿from￿19.2 kBit/
s￿to￿20.0 kBit/s.
Examples:
• 19.2￿kBit/s￿FLEL,￿FLER
• 20.0￿kBit/s￿remote￿control￿receiver
The￿Body￿Domain￿Controller￿is￿designed￿for￿the￿different￿data￿rates￿at￿the￿corresponding￿inputs.
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