Bit-serial data interface (BSD)

The bit-serial data interface is a single-wire data bus with a data transfer rate of 1.2 kBd.

The following components are connected across the bit-serial data interface with the DDE control unit:

• Alternator
  
• Intelligent battery sensor (not on E83)
  
• Combustion preheating control unit (only on E83)
  
• Electric coolant pump (depending on variant)
  
• Oil condition sensor (not on E83)
  

Only DDE control unit: Each component connected across the BSD is connected to its own pin on the DDE control unit. However, these pins are interconnected in the control unit.

Function

The following data is interchanged between the DDE and the connected components:

• Function commands from the DDE to the components
  
• Identification data of the components to the DDE
  
• Operating values of the components and their functions to the DDE
  
• Error messages of the components to the DDE
  

Diagnosis

The DDE monitors the communication across the bit-serial data interface to the connected components. This means that wire faults are also detected.

The connected components have their own diagnosis functionality and monitor the following:

• The executed functions are monitored for faults (e.g. defective preheating circuit for the combustion preheating control unit)
  
• Internal faults in the components
  

If a component detects a fault, it reports the fault across the bit-serial data interface to the DDE. The DDE then enters the fault in the fault code memory.