In the ECU Mode real sensors will be connected and the ECU will be simulated by the SPI-Simulyzer.

| ECU-Mode | SPI-Simulyzer functions: |
| Real sensors | Supply with voltage |
| Recording of the sensor data | |
| Simulierte ECU | Generation
of the master data (Command sequence of the start and the measurement phase) |
| SPI-BUS | Generation of the BUS parameter according to the definition. |
To simulate a control unit (ECU) following steps are necessary at minimum:
In any order and only if the predefined values differ from the desired values (BUS-Parameter):

After the first definition of all parameters of a BUS configuration, the configuration can be saved as an empty project.After that it can be loaded at any time.