MOST ring function - GF82.00-P-0004T
Model 211.0/2
Sequence of the MOST components with code (525) MB Audio 50 APS radio and with code (813) voice control system (VCS) and with code (819) 6-disk CD changer
Scheme 489
Digital MOST
The digital MOST is a networking system that utilizes the possibilities of optical information transfer.
With this system, the data is transferred by light pulses. The light pulses are transferred to the components that are connected to the MOST (for example: CD changer (A2/6), telecommunications control unit (N112)) with the help of a fiber optical cable. Commands given to the components, e.g., push the "Play" button on the radio (radio control panel and navigation unit (A2/56) (command for the CD changer) have to be converted into light pulses (optical information (A2/6)) via the MOST for further transmission. The light pulses are then turned into electrical signals in the receiver component in order to execute the command.
Because of its extremely high transfer rate the MOST source data and control data can be transmitted simultaneously. This reduces the quantity of wiring considerably.
Thus, the connected components only require 2 lines for the voltage supply, 2 lines (input/output) for the fiber optical cable of the digital MOST and 1 line for the wake-up signal.
Moreover, a number of audio (AF) signals, can be transferred simultaneously via the fiber optic cable without any negative effect on the information contained.
Data transmission using fiber optic cable has the following advantages
- Extremely high data transmission rate
- Prevents tapping and cross-talk
- Data transmission is not sensitive to electromagnetic radiation
- Short-circuit resistance
- Floating connection to the MOST participants
- No oxidation
- Low weight of fiber optical cable
- Small line diameter
The MOST has an enclosed ring structure. The components are arranged in a ring line (series circuit). This arrangement is adapted according to the series.
The information is transmitted in only one direction, in other words the light pulses for the CD changer (A2/6) run through all components found at the MOST.
The radio control panel and navigation unit (A2/56) has a central function within the ring structure of the MOST. As a result of the ring structure, all other ring subscribers can be served.
When the system is first put into operation, a system test is performed. During the test, the individual components and their sequence in the ring structure of the MOST are recorded by the audio gateway control unit (N93/1) and compared to the source and control data of the equipment-specific sequence of the data that is stored in the plant.
With the assistance of the STAR DIAGNOSIS the components in the audio gateway control unit (N93/1) can be re-coded (e g. variant coding).
The MOST is rendered diagnosis capable via the audio gateway control unit (N93/1).
| Data transmission, function | GF82.00-P-2000T |
Fiber Optic Cables for Media Oriented System Transport (MOST), As-Built Configuration - GF82.00-P-0801T
MODELS 211.0/2 with CODE (494a) USA version
Scheme 490
Shown is the routing of the fiber optic cables for Media Oriented System Transport (MOST) - vehicles as of 09/03 with COMAND, with code (819) CD changer (6-disc) and with satellite digital audio radio service (SDARS) (Dealer Option Kit)
Fiber optical cable (1) from the COMAND operating, display and control unit (A40/3) to the CD changer (A2/6).
- Routed behind center console
Fiber optical cable (4 or xx1) from CD changer (A2/6) to the fiber optical cable connector (MOST) (X39/50).
- Routed from the frame floor system into the left rear legroom area (rocker panel area).
Fiber optical cable (5) from the fiber optical cable connector (MOST) (X39/50) to the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11).
- Routed behind the rear bench seat underneath the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (7) from the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11) up to the separation point at the control unit carrier.
- Routed behind the rear bench seat and under the trim cover of the control unit carrier.
Fiber optical cable (11) from the separation point of the control unit carrier to the telecommunications control unit (N112).
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (13) from the telecommunications control unit (N112) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (14) from the fiber optical cable connector (MOST) (X39/50) to the navigation processor (N41/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (16) from the navigation processor (N41/1) to the fiber optical cable connector (MOST) (X39/50).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (20) from the fiber optical cable connector (MOST) (X39/50) to the audio gateway control unit (N93/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (22) from the audio gateway control unit (N93/1) to the COMAND operating, display and control unit (A40/3).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area) and then toward the front into the frame floor system.
On vehicles with SDARS (Dealer Option Kit)
Fiber optical cables (8, 10) from the separation point of the control unit carrier to the SDAR control unit (N87/5).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and over the right rear wheelhouse.
Scheme 491
Shown is the routing of the fiber optical cables for Media Oriented System Transport (MOST) - vehicles as of 09/03 with COMAND, with SDARS (Dealer Option Kit) and without code 819, CD changer (6-disc)
Fiber optical cable (xx1) from the COMAND operating, display and control unit (A40/3) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the center console into the frame floor system and into the rear legroom area (rocker panel area).
Fiber optical cable (5) from the fiber optical cable connector (MOST) (X39/50) to the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (7) from the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11) up to the separation point at the control unit carrier.
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (11) from the separation point at the control unit carrier to the telecommunications control unit (N112).
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (13) from the telecommunications control unit (N112) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (14) from the fiber optical cable connector (MOST) (X39/50) to the navigation processor (N41/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (16) from the navigation processor (N41/1) to the fiber optical cable connector (MOST) (X39/50).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (20) from the fiber optical cable connector (MOST) (X39/50) to the audio gateway control unit (N93/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (22) from the audio gateway control unit (N93/1) to the COMAND operating, display and control unit (A40/3).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area) and then toward the front into the frame floor system.
On vehicles with SDARS (Dealer Option Kit)
Fiber optical cables (8, 10) from the separation point at the control unit carrier to the SDAR control unit (N87/5).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and over the right rear wheelhouse.
Scheme 492
Shown is the routing of the fiber optic cables for Media Oriented System Transport (MOST) - vehicles up to 09/03 with Audio 50, with code 819 CD changer and with satellite digital audio radio service (SDARS) (Dealer Option Kit)
Fiber optical cable (1) from the radio control panel and navigation unit (A2/56) to the CD changer (A2/6).
- Routed behind center console
Fiber optical cable (4 or xx1) from CD changer (A2/6) to the fiber optical cable connector (MOST) (X39/50).
- Routed from the frame floor system into the left rear legroom area (rocker panel area).
Fiber optical cable (5) from the fiber optical cable connector (MOST) (X39/50) to the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (7) from the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11) up to the separation point at the control unit carrier.
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (11) from the separation point at the control unit carrier to the telecommunications control unit (N112).
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (13) from the telecommunications control unit (N112) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (20) from the fiber optical cable connector (MOST) (X39/50) to the audio gateway control unit (N93/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (22) from the audio gateway control unit (N93/1) to the radio control panel and navigation unit (A2/56).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area) and then toward the front into the frame floor system.
On vehicles with SDARS (Dealer Option Kit)
Fiber optical cables (8, 10) from the separation point at the control unit carrier to the SDAR control unit (N87/5).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and over the right rear wheelhouse.
Scheme 493
Shown is the routing of the fiber optical cables for Media Oriented System Transport (MOST) - vehicles up to 09/03 with Audio 50, with SDARS (Dealer Option Kit) and without code 819, CD changer (6-disc)
Fiber optical cable (xx1) from the radio control panel and navigation unit (A2/56) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the center console into the frame floor system and into the rear legroom area (rocker panel area).
Fiber optical cable (5) from the fiber optical cable connector (MOST) (X39/50) to the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (7) from the control unit for the hands-free system (A35/1) or the control unit for the voice control system (VCS) (A35/11) up to the separation point at the control unit carrier.
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (11) from the separation point at the control unit carrier to the telecommunications control unit (N112).
- Routed behind the rear bench seat under the trim cover of the control unit carrier.
Fiber optical cable (13) from the telecommunications control unit (N112) to the fiber optical cable connector (MOST) (X39/50).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and then toward the front over the left rear wheelhouse and into the rear legroom area (rocker panel area).
Fiber optical cable (20) from the fiber optical cable connector (MOST) (X39/50) to the audio gateway control unit (N93/1).
- Routed from the rear legroom area (rocker panel area) and over the left rear wheelhouse.
Fiber optical cable (22) from the audio gateway (N93/1) to the radio control panel and navigation unit (A2/56).
- Routed over the left rear wheelhouse and into the rear legroom area (rocker panel area) and then toward the front into the frame floor system.
On vehicles with SDARS (Dealer Option Kit)
Fiber optical cables (8, 10) from the separation point at the control unit carrier to the SDAR control unit (N87/5).
- Routed behind the rear bench seat under the trim cover of the control unit carrier and over the right rear wheelhouse.
Data transmission function - GF82.00-P-2000T
Model 211.0/2
Data transfer in MOST
The audio gateway control unit (N93/1) makes it possible to provide all the information on the CAN interior (CAN-B) to each respective component in the MOST. It acts as an interface (gateway). To this end signals arriving at the audio gateway control unit (N93/1) are converted such that they can be sent by the MOST to the CAN interior (CAN-B) and vice versa. It is the clock-pulse generator that transmits information segments (data frames) on the bus system. A frame consists of 2 subframes. The sequence of many data frames then contains the complete information for the operation of the MOST components.
Light pulses are converted into electrical signals and back again by means of the optical transmitter and receiver diodes, which are integrated into every MOST component.
The MOST components can then receive or transmit the electrical signals. Source data and control data are transmitted.
The source data are transmitted synchronously, for instance as they are available on an audio CD, as blocks in subframes. By contrast, the control data are transferred asynchronously. They are split up, distributed using several subframes and sent off.
The control data are provided with an address (Code), which indicates for which MOST components the data are intended. Information arriving at the component is recompiled as individual data packages in the component and can then be processed. A data frame can thus contain the most varied of information (source and control data of all the components in the MOST).
The transmitting and receiving units are switched off when they are not required, in order to lower the quiescent current consumption (sleep mode). They are immediately switched off after the radio control panel and navigation unit (A2/56) is switched off or after the transmitter key (A8/1) is removed.
With a new optical information transmission start, the MOST can be activated with the help of the "ON switch (On/Off) of the radio control panel and navigation unit (A2/56) or by turning the transmitter key (A8/1) into position "circuit 15R ON", provided the system was not shut off before the transmitter key (A8/1) was removed. It is activated by an electrical signal in the wake-up line, which is actuated by the audio gateway control unit (N93/1).
With integrated telephone and inserted transmitter key (A8/1) it is also possible to actuate a wake-up call if a call comes in
Scheme 494
Regardless of the fact for which component the information is intended during the start, the edited light signal arrives at the MOST at full intensity.
| Wake-up function | GF82.00-P-2001T |
Wake-up function - GF82.00-P-2001T
Model 211.0/2
Since the transmitting and receiving diodes are automatically shut off if they are not needed (sleep mode), a command from the radio control panel and navigation unit (A2/56) or a wake-up pulse, which activates the system, is required to start a new data transfer.
This is accomplished via the separate wake-up line. For this purpose the audio gateway control unit (N93/1) actuates a wake-up signal (electrical signal), which allows the voltage in the wake-up line to decrease to a defined value. A chip in the components recognizes by the duration of the signal that it is a wake-up signal and the MOST is activated.
A wake-up can be activated for instance by the telephone system through an incoming telephone call during the run-on phase.
Diagnose Wake-up
In order to diagnose the wake-up circuit in the components the audio gateway control unit (N93/1) can be prompted via STAR DIAGNOSIS to actuate a wake-up diagnosis signal. This signal differs from the wake-up signal by the fact that it has a significantly longer duration. The components react with a signal on the wake-up line (message to the audio gateway control unit (N93/1)).
This allows the audio gateway control unit (N93/1) to recognize, which components received the long wake-up pulse. The diagnostic wake-up can only be actuated when the optical ring cannot be activated due to an error. If all components answer the audio gateway control module (N93/1), the voltage supply is correct.
| Fiber optical cable location/design/function | GF82.00-P-4000T |
Fiber optic cable, function - GF82.00-P-4000-04T
The light for data transmission in the MOST ring has a wave length of 650 nm. Visible light is in the range of blue with 400 nm to red with 800 nm.
Optical damping of the light signal may occur in the fiber optical cable.
This attenuation is dependent on
- the length of the line between the components
- Bending radii for routing (minimum bending radius 25 mm)
- the condition of the insulation of the fiber optical cable (mechanical damage, pinching)
If a ring subscriber fails, it can be removed from the MOST. In order to assure the functional availability of the remaining components, the MOST has to be closed again with passive connectors.
The fiber optical cable consists of plastic with a fiber diameter of 1 mm. Each fiber optical cable is protected against mechanical damage and against admission of outside light with the help of an orange-colored insulation.