This tutorial provides a closer look into the simulator by explaining how to use the simulator to tune the parameters of a PID controller. The PID controller and a model of the physical system are already defined in an example project that came with the installation of RTflow, so there is no modeling work involved in this tutorial. Instead, you will iteratively modify the controller parameters and run simulations until a satisfying step response has been achieved. Notice that a basic knowledge of PID controllers is helpful for fully understanding this tutorial.