You can create additional control units for a selected controller. Click on the Create... button in the Control Unit List dialog to display the Create Control Unit dialog. Enter the control unit information and press OK. Note that control units have the same serial number as the controller containing them; thus, the serial number shown in this dialog can be only edited in the Edit Controller dialog . The control unit is added to the controller in the diagram, and appears in the Control Unit List dialog for the controller.
You can also create one or more switch 's control units inside a switch. When you create a new switch 's control unit inside a switch, it is always connected to port FE of the switch. If you define an existing control unit for a switch, note that this control unit is added into the appropriate switch 's internal structures. Internal structures of the switch are the switch 's control units and devices. You must specify either both a control unit and a device or neither.