The aim is to find out as early as possible whether the diagnostic functionality of the ECU's application software is working. This usually requires a special diagnostic tool that is connected to the finished ECU via the CAN bus.
The diagnostic functionality of the ECU can be tested only at the end of the development process. This means that feedback on the functionality and possible errors of the application software can first be provided long after its development has been completed. A complete ECU contains considerably more software than is tested within the scope of diagnostic tests. Therefore, the search for error sources in the context of diagnostic tests is much more complex than an isolated test of the diagnostic functionality.
The dSPACE tool chain offers a solution for testing the diagnostic functionality of the application software at an early stage. SystemDesk can be used to flexibly create a virtual ECU (V-ECU) on the basis of the application software. SystemDesk also lets users integrate production-ready basic software (BSW), which is required for diagnostics, for example.
Instead of the complete BSW, however, only the BSW modules required for diagnostics via CAN are integrated. ControlDesk can be used as a diagnostic tester and exchange exactly the same diagnostic messages with the V-ECU as with a real ECU. In this case, the messages are exchanged via the virtual CAN bus simulated by VEOS.
The application software collects sensor data, performs calculations based on this data, and can therefore detect sensor failures. The detected failures are stored as diagnostic trouble codes (DTC) in the fault memory, where they are read out by ControlDesk as the diagnostic tester. The fault memory is implemented with the Diagnostic Event Manager (DEM) and NvRAM Manager (NvM) modules.
To read the fault memory, ControlDesk as a diagnostic tester sends diagnostic messages to the V-ECU via the simulated CAN bus. The messages are forwarded through the CAN stack of the V-ECU to the Diagnostic Communication Manager (DCM). The DCM processes and responds to the diagnostic queries and accesses the fault memory of the DEM.
In this example, the DEM and DCM modules as well as the CAN stack are implemented with basic software from a third-party vendor.
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