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:

• DeviceID. FBlockID. InstID. FktID. OPType

This means:

• DeviceID - ID-number of one or several control modules in the network
• FBlockID - ID-number of a function unit, for example, the CD-function in the integrated audio module (IAM)
• InstID - the ID-number to differentiate two identical function units, for example, for two Integrated Audio Modules (IAM)
• FktID - The ID number of the function to be activated, for example play or stop
• OPType - Specifies how function is to be used, since a function can be used in different ways.

The message may appear as follows:

• 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.