You do not need to download additional software but you do need an additional license in order to use the PLECS Coder. To request a trial license for the PLECS Coder, please email Plexim at info@plexim.com.
As for the steps to follow, there is a demo model for code generation:
- Open the Demo Browser by choosing the menu "Window > Demo Models".
- In the frame on the left hand side click on the tab "Search". (If the frame is hidden, click on the tool button with the magnifying glass.)
- Enter the search term "code generation" and click on "Search".
- Choose the first hit "PLECS Demo: CodeGen3phThyRect.plecs" and click on the link "Open this model" on the top right to open the demo model.