Every external control in the Control Systems dialog has a property dialog that allows you to view the current setting of the control or change its value (or trigger the action in the case of a Command control).
Open the External Control Systems dialog box by clicking on the Control Systems button toolbar in the processing workspace and then clicking on External Controls.
Ensure that the external control that you want to open is visible by clicking on the tab for the control type and then scrolling the list if necessary so that your external control is visible.
Click on the underlined name of the control, which is a hyperlink that opens the control’s property dialog.