You can use these Device Variables () in the equations of the same device model or any device model that inherits from it. Right-click a Device Model or Device Model Feature node and choose Device Variables from the Devices submenu.

Fill in the table columns and rows with the variables needed. Enter a Name and specify an Expression for a variable. This directly defines an equation for the variable. This is equivalent to defining an equation with the right-hand side set to the variable name and the expression as the left-hand side.

When added under a Port Model node, this section is called Port Variables, and a Flow variable column is available. Select the checkbox in the Flow variable column for a variable to indicate that the variable is treated as a flow in connections between ports.

Click the Edit Variable button () underneath the table to edit these settings and others for the selected variable. See Edit Variables for Device Variables, Device Parameters, Device Constants, Device States, Discrete Device States, and Port Variables for more information.