ML 320 (163.154) V6-3.2L (112.942) (1998)
Information Bus: Description and Operation
CAN Data Bus, Function
CAN Data Bus, Function
Shown on example of Controller Area Network bus class C (engine compartment) (CAN-C) in model 220 with engine 112, 113
A1
Instrument cluster
AN3/10
ME-SFI [ME] control unit
AN15/3
ETC control unit
AN15/5
Electronic selector lever module control unit
AN22
AAC [KLA] control and operating unit
AN47
Traction systems control unit
AN51
AIRmatic with ADS control unit
AN63/1
DTR control unit (with code (219a) Distronic (DTR))
AN73
EIS control unit
AN80
Steering column module
Task
- Data interchange between the individual control units
- Readying sensor signals for several systems
- Reducing the number of wires
- Improving the electromagnetic compatibility
Design
The data bus consists of a twisted two-strand data line which connects all the participants to each other in a parallel circuit. The data line lines must not
be mixed up (low or high level). With respect to bus adaptation the ME control unit (N3/10), DAS [FBS] control unit (N73/1) (model 163), DAS [FBS]
radio frequency/infrared control unit (N54/4) (model 129) and DAS [FBS] radio frequency control unit (N54/3) (model 170) apply as a terminal . In
each case a terminating resistor of 120 ohms is installed for this (exception ME control unit (N3/10) on engine 120: 240 ohms each).
Mote: For the resistance measurement of the data line (circuit 15 OFF) the various terminating resistors in the terminals are connected in parallel.
Function
The data are transmitted digitally at various intervals on the data bus. The individual data blocks are defined in a protocol and this also states which data
are received or transmitted by a control unit. Each connected control unit is able to transmit or receive data.
The total of the data blocks, the short pause between two transmission intervals and further properties of the data bus are checked constantly. Any faults
detected are stored.
Vehicles with EIS [EZS] control unit (N73)