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