XC90 FWD L6-3.2L VIN 98 B6324S (2007)
A data frame consists of different parts. This contains for example:
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control data
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asynchronous data
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synchronous data and
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administrative data.
A data frame on the MOST network is 64 bytes. The data frame consists of the following:
1. synchronization of the clock on the MOST network, i.e. the frequency at which data is transmitted so that the data is sent at the correct intervals
2. administrative data, indicates the size of the asynchronous and synchronous data
3. synchronous data
4. asynchronous data
5. control data
6. administrative data.
16 data frames are required to form a block. One block is the minimum size of a MOST message.
MOST protocol
All activations on the MOST network are control messages or MOST messages. The majority of the MOST messages are initiated by the infotainment
control module (ICM). The infotainment control module (ICM) informs certain control modules if a function in the control module must be activated.
The infotainment control module (ICM) then allocates space to transmit data on the MOST network for those activations which have been initiated in the
control modules. This is either synchronous or asynchronous data. The structure of a message is as follows:
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DeviceID.FBlockID.InstID.FktID.OPType
This means:
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DeviceID - The ID number of one of more control modules in the network
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FBlockID - the ID number of a function unit, for example the CD function in the Integrated Audio Module (IAM)
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InstID - ID number to differentiate two identical function units, for example two CD control modules in the MOST network
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FktID - The ID number of the function to be activated, for example play or stop
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OPType - Specifies how the function is to be used, because a function can be used in different ways.
The message may appear as follows:
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IAM.CD.01.Track, Length.Set(10)
This means: play song number 10 on the CD player in the Integrated Audio Module (IAM).
The infotainment control module (ICM) knows which control modules are in the MOST network. It can then assign specific ID numbers to all control
modules and the included functions. If control modules are removed or added, the ID numbers for the control modules are re-assigned.
Calculating the transfer rate
