418-00 Module Communications Network: Description And Operation (page 6 of 7)

Steering angle sensor  
Air suspension  
Electric park brake  
Electronic rear differential control module  
Terrain Response™  
Restraint control module  
Engine control module  
Transmission control module  
Adaptive front lighting system control module  
Antilock Braking System (ABS) control module  

Both the medium and high speed CAN bus are connected to the Instrument cluster and the diagnostic socket at one end. 
The Medium speed bus terminates at the Central Junction Box (CJB), while the high speed bus terminates at the ABS 
control module. 
 
Control modules are connected in either a loop , CAN in/ CAN out, or a spur configuration. Should a control module that is 
looped fail that bus system will fail at that point. Should a spurred control module fail the rest of the bus system will be 
unaffected by the faulty control module. 
 

Media Orientated System Transport (MOST) 

The MOST bus uses a fibre optic cable to transport data and audio around the entertainment and information system. The 
fibre optic cable is arranged in a ring, with each unit on the bus having a MOST in and MOST out. 
 
MOST is a synchronous network. A timing master supplies the clock and all other devices synchronize their operation to 
this clock. The timing master for the MOST network is the integrated head unit (IHU). 
 
Key features of the MOST network are: 
 

Simple connectors  
Reduced cabling  
Support of asynchronous and synchronous data transfer  
Support for up to 64 devices  
High data transfer rate  

When handling the MOST fibre optic cables the following safety precautions should be observed: 
 

The cable has a minimum bend radius of 25mm.  
It is advisable not to look directly into the connector of a live cable.  
The MOST cable cannot be repaired, replacement overlay harnesses will be available to replace damaged cables. 

Gigabit Video Interface (GVIF) 

The GVIF bus is a Sony proprietary bus for the transmission of video between a transmitter device and a display device. 
In this instance it is used to transmit video from the navigation computer to the Touch Screen Display (TSD) only. 
 

Local Interconnect (LIN) bus 

There are two LIN buses on the vehicle. One connects the Rain sensor, Sunroof and Memory seats to the central junction 
box and the other connects the BBUS to the central junction box. 
 
The LIN bus has a master/ slave configuration. Within the master is stored a 'schedule table' which is a list of all the LIN 
frames or packets in order of which one gets sent when and how many times within a particular cycle. The Master sends 
out a header on the bus which will identify to the slaves whose turn it is to transmit a frame. The slave then fills the space 
after the header with the contents of the frame. The frame identifiers are all sourced from the LIN specification, and the 
frame identifiers are grouped by the size of the frame in bytes. All the LIN nodes are optional fit, consequently there is a 
different schedule table for each permutation and the Bus master switches between these based on the information held 
within the car configuration file. The CJB also acts as a bi-directional gateway between the MS-CAN bus and the LIN bus 
by passing signals between the two buses. 
 
The bus is a single wire and operates at 9.6Kbs. The protocol used on the LIN bus is defined by the LIN consortium.