Bit-serial data interface (BSD)

Bit-serial data interface (BSD) in the S54

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

The following components in the S54 engine are connected across the bit-serial data interface with the DME/DDE control unit:

• Alternator
  
• Oil condition sensor (depending on variant)
  

Function:

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

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

Diagnosis:

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

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

• 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 DME. The DME then enters the fault in the fault code memory.