Double-click on the desired controller to open the Controller dialog. The Strings/Devices section in the dialog lists any strings/devices connected to the controller through its device interfaces. If I/O devices have no physical string (they are integrated into the controller), the “virtual strings” containing them are displayed.
Select a string/device and press the Edit... button to display the String dialog. You can then open the Select Controller Device Interface dialog by selecting one or more string interfaces and pressing the Connect... button.
Note that you can also open the String dialog by choosing String... from the Edit menu, or by double-clicking on a string in the configuration diagram.
Figure 1. Select Controller Device Interface