This is so since the engine dynamics may change abruptly at times other than the simulation time instants, in the case of fixed-step simulations. This phenomenon usually results in a loss of accuracy. If one uses variable-step simulations. A closed-loop engine control system separated onto two target processors and connected to a data acquisition and monitoring host processor is shown on the diagram.
Such a configuration is ideal for a subsequent HIL setup where the actual Electronic Control Unit (ECU) replaces its simulated counterpart. In the table, the execution time per simulation step shows that the real-time capability is assured for a step size superior than about 255 microsecon.
