System time safety system

The BYTEFLIGHT bus system has a star-shaped structure. The individual satellites (= control modules with/without sensors) are interconnected across a star connector by means of fiber-optic cables. The star connector in the BYTEFLIGHT bus system is the Safety and Information Module (SIM) or the Safety and Gateway Module (SGM). Depending on the vehicle, the star connector is the SIM or the SGM. In the rest of the description, both the SIM and SGM will be mentioned.

In the safety system, there is a uniform system time for all control modules. On production of the vehicle, the system time is started by means of a diagnosis command. This operation is only possible once, which means that resetting the system time is not possible. The system time is increased with every synchronization impulse generated on the BYTEFLIGHT bus. The Safety and Information Module (SIM) or Safety and Gateway Module (SGM) is the bus master controller and this responsible for generating the synchronization impulses. The SIM or SGM sends the message ”system time” to all BYTEFLIGHT control modules. The control modules only adopt that time if

• the time stored on the control module is not greater than the time transmitted by the SIM or SGM or if
  
• no time has yet been stored on the control module, i.e. the control module concerned is a new one.
  

Main functions

Synchronization of New Control Modules

When a control module in the safety system is replaced, the system time is started automatically after the coding-programming process. If the system time has not automatically been started after the coding-programming process, the fault memory entry: ”System time error” is entered in the control module. The service function can then be used to subsequently start the system time manually. In addition, the status ”System time started/not started” can be displayed. For the BYTEFLIGHT control modules, the system time is to be started manually afterwards if this has not taken place automatically after the coding-programming process. The following procedure is then required for the BYTEFLIGHT control modules:

• Satellite: initialize system time
  

Important

• If no vehicle identification number or an incorrect vehicle identification number has been entered in a control module, the system time cannot be started! The control module must be reprogramd first.
  
• If a system time error occurs, this is saved in the relevant control module.
  

Service functions

Notes on safety

In all cases, only perform work on the fuel pump with the ignition off!

All work on the airbags must be carried out with the battery disconnected!

Connect and disconnect all BYTEFLIGHT control modules, sensors and generators only with the battery disconnected!

If a fiber-optic cable on the BYTEFLIGHT bus has to be repaired, it must be borne in mind that there may only be one join in a fiber-optic cable. If there is already a join due to a door connector, the fiber-optic cable must not be repaired. In the case of a defect, the fiber-optic cable must be replaced!