Hi Esther Kang,
The switch in the example is for the reversal of the motor shaft. Suppose you need to control the motor speed in the anti-clockwise direction for some duration and in the clockwise direction after anti-clockwise rotation, and you need the speed reversal to happen dynamically while the model runs without running the model twice in different directions. In that case, the Switch block becomes very useful.
I am attaching a photo of the measured speed where the motor speed is reversed after 3 seconds, i.e., I have provided a negative speed reference in the "Speed_Ref_Final (rpm)" Constant block.
However, if you need to control the motor for a constant reference speed, you can omit the Switch and the Step function block and use a Constant block to provide a constant reference speed.
You can find more information on the Switch block in the following documentation.
Hope this answers the query.
