BMW E65 User Manual download pdf (Page 35)

E65 Bus Systems

Functional Description

Data Transport

MOST currently offers a band-width of 22.5 Mbits/s . In the next generation, the band-width

will be increased to 50 and then later to 150 Mbits/s (as of approx. 2002).

In order to meet the different requirements of the applications regarding data transport,

each MOST message is divided into three parts:

• Control data

• Asynchronous data: e.g. navigation system, arrow

representation

• Synchronous data: e.g. audio, video signals

The control data controls the functions and devices in the network. The information can be

compared to CAN bus data.

The control data has a band-width of 700 Kbit/s. That corresponds to around

2700

mes-

sages per second.

For the data transmission of synchronous and/or asynchronous data, there is a total of 60

bytes. The limit is variable: e.g. 20 bytes of synchronous data and 40 bytes of asynchro-

nous data.

A message over the MOST

Control Data

700 kB/s

2700 S/S

CAN bus

Asynchronous

Data

e.g Navigation (arrow

display)

Synchronous data

Audio

Video

Data Transport on the MOST

Different data is “packaged”

and then sent as one mes-

sage to be “unwrapped” by

next device on the MOST

ring.

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BMW E65 User Manual Page 35