When Simulink components are imported into a Rational Rhapsody model, the .cpp files generated from the Simulink model using Real-Time Workshop are included as source files in the Rational Rhapsody‑generated makefile.
In terms of Rational Rhapsody‑generated code, SimulinkBlock elements in Rational Rhapsody are classes that are based on a framework class called OMSimulinkBlock. The superclass periodically calls the method doStep(), which is implemented by the derived class. This method initializes the input port, calls the step function in the Simulink‑generated .cpp file, and sets the value of the output after the step. (The output is then relayed through the output flow port.)
The doStep() function will be generated once you assign the SimulinkBlock with a Simulink model and use the Import/Sync Simulink Model menu command. Note that an Embedded Coder License (ERT) is required for this operation.