Mercedes-Benz ML320. Service manual - part 219

 

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Mercedes-Benz ML320. Service manual - part 219

 

 

DATA TRANSFER, FUNCTION - GF82.00-P-2000A 

MODEL 129 as of 1.6.98, 163, 168 as of 1.9.98, 170, 202 as of 1.6.98, 203, 208, 210 as of 1.6.98, 215, 220  

The Digital Data Bus (D2B) contains the master unit, e.g. the radio (A2) except for model 129, and model 202, 
which triggers all the components in the Digital Data Bus system (D2B). The master unit also serves as an 
interface (Gateway) to the CAN interior (CAN-B). For this purpose, signals arriving at the master unit are 
converted so that they can be transmitted from the Digital Data Bus (D2B) to the CAN interior (CAN B) and 
vice versa. Moreover, the master unit serves as a timing circuit which provides the clock pulse with which the 
information frames are transferred on the Digital Data Bus (D2B). A frame consists of 2 subframes. A series of 
many data frames contains the complete information for proper operation of the components located at the 
Digital Data Bus (D2B). The conversion of optical pulses into electrical signals and vice versa is done by 
transmitter and receiver diodes, that are integrated into each component. Each of the components receives or 
transmits the electrical signals from the chip of the Digital Data Bus system (D2B) as a "D2B log". Source data 
and control data are transmitted. 

The source data are transferred synchronously, for example as present on a music CD, as 32 bit blocks into the 
subframes. By contrast, control data are transferred asynchronously. They are divided up (2 bits per subframe) 
and distributed over several subframes. The control data are provided with an address, which indicates for 
which components the data are intended in the Digital Data Bus (D2B). The individual data packages are joined 
together again in the components and they can then be processed. A data frame can therefore contain highly 
differing types of information (source and control data from all components mounted in the digital data bus 
(D2B)). The transmission and reception diodes as well as the digital data bus (D2B) chip are switched off when 
not required in order to reduce the quiescent current (sleep mode). Switch-off is accomplished immediately 
when the master unit or circuit 15 is switched off. After restart, the digital data bus system (D2B) can be 
activated either by the components or by the master unit by means of an electrical signal in the wake-up line for 
optical data transmission. 

Regardless whether the information is intended for a component, it feeds an edited light signal back into the 
digital data bus (D2B) at full intensity (repeater function). 

WAKE-UP, FUNCTION - GF82.00-P-2001A 

MODEL 129 as of 1.6.98, 163, 168 as of 1.9.98, 170, 202 as of 1.6.98, 203, 208, 210 as of 1.6.98, 215, 220  

Normal wake-up  

 

Digital data bus (D2B), function

 

GF82.00-P-0001A

 

Data transfer, function

 

GF82.00-P-2000A

 

Wake-up, function

 

GF82.00-P-2001A

 

Survey of system components, digital 
data bus (D2B), 
location/task/design/function

 

GF82.00-P-9999A

 

Wake-up, function

 

GF82.00-P-2001A

 

2001 Mercedes-Benz ML320 

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

  

me 

 

Since the transmitting and receiving diodes along with the digital data bus system's (D2B) chip are 
automatically shut off if they are not needed (sleep mode), 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 
master unit actuates the wake-up signal (electrical signal), which allows the voltage in the wake-up line to 
decrease to a defined value. The chip of the digital data bus system (D2B) in the components recognizes on 
account of the duration of the signal that this is a wake-up signal, and the digital data bus (D2B) is then 
activated. Therefore the digital data bus (D2B) is then in an activated state. A "wake-up" can take place in a 
quiescent system (sleep mode) even without the wake-up pulse of the master unit by activation of a component 
located at the digital data bus (D2B). 

Wake-up diagnosis  

For diagnosis of the wake-up circuit in the components, the master unit can trigger a wake-up diagnosis signal 
using STAR DIAGNOSIS and the data link connector (X11/4). This signal differs from the wake-up signal by 
the fact that it has a significantly longer duration. The components react to this long wake-up pulse with a signal 
on the wake-up line (message to master unit). This allows the master unit to recognize which components have 
received the long wake-up pulse. The wake-up diagnosis signal can only be actuated when the digital data bus 
(D2B) cannot be activated due to an error. If all components reply to the master unit, then their voltage supply is 
correct. 

FIBER OPTIC CABLE, LOCATION - GF82.00-P-4000-01GH 

Model 163  

Components for ECE version  

 

Fiber optical cable, 
location/task/function

Except model 208.4

GF82.00-P-4000A

 

2001 Mercedes-Benz ML320 

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

  

me 

 

Fig. 6: Identifying Fiber Optic Cable Components Location 

FIBER OPTIC CABLE, FUNCTION - GF82.00-P-4000-04A 

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. 
The light for the data transfer in the digital data bus (D2B) has a wavelength of 650 nm; by comparison, visible 
light lies in the range of blue with 400 nm to red with 800 nm. Optical attenuation of the light signal can occur 
in the fiber optic cable. Attenuation of the optical signal in the fiber optical cable is dependent on: 

the length of the line between the individual components  

the bending radii when routing the fiber optical cable, which must have min. bending radius = 25 mm  

the condition of the insulation of the fiber optical cable  

A passive connector; this is used when a component is removed from the digital data bus (D2B) due to a 
fault.  

To ensure the functional availability of the remaining components, the digital data bus (D2B) is closed again 
using a passive connector. The fiber optical cable has two different connection ends: 

The fiber optical cable input, which is the output to each control unit. This is marked in "white".  

The fiber optical cable output, which is the input to each control unit. This is marked in "red".  

FIBER OPTIC CABLE, LOCATION/TASK/FUNCTION - GF82.00-P-4000A 

MODEL 129 as of 1.6.98, 163, 168 as of 1.9.98, 170, 202 as of 1.6.98, 203, 208.3, 210 as of 1.6.98, 215, 220

 

2001 Mercedes-Benz ML320 

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

  

me 

 

Exemplified on model 215 with code (819) 6-disc CD changer, with code (810) Sound System and with 
code (382) MB phone "CTEL" in console on right side of dome
  

Fig. 7: Identifying Fiber Optic Cable, Location/Task/Function 

SURVEY OF SYSTEM COMPONENTS, DIGITAL DATA BUS (D2B), LOCATION/ TASK/DESIGN/FUNCTION - GF82.00-P-
9999A 

MODEL 129 as of 1.6.98, 163, 168 as of 1.9.98, 170, 202 as of 1.6.98, 203, 208, 210 as of 1.6.98, 215, 220  

 

Fiber optic cable, location Model 129

GF82.00-P-4000-01D

 

 

Model 163 as of 01.09.01 GF82.00-P-4000-01GH

 

 

Model 168

GF82.00-P-4000-01E

 

 

Model 170

GF82.00-P-4000-01C

 

 

Model 202, 208

GF82.00-P-4000-01B

 

 

Model 203

GF82.00-P-4000-01G

 

 

Model 210

GF82.00-P-4000-01A

 

 

Models 215, 220

GF82.00-P-4000-01F

 

Fiber optic cable, purpose The fiber optical cable is 

responsible for the optical 
data transfer of the 
components located at the 
digital data bus (D2B).

 

 

Fiber optic cable, 
function

 

GF82.00-P-4000-04A

 

Fiber optic cable, 

Except model 208.4

GF82.00-P-4000A

 

2001 Mercedes-Benz ML320 

1998-2005 ACCESSORIES & BODY, CAB Electrical System - Body - 163 Chassis

  

me 

 

 

 

 

 

 

 

 

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