Once you have created a control in the Control Systems dialog it can’t do much until it is linked to another control of the same type that performs a useful function in your HAL configuration. Creating a control link for an external control is very similar to how you create any control link in the HAL System. This is fully explained in the Creating Control Links topic, here is the process specifically for external controls.
Open the External Control Systems dialog box by clicking on the Control Systems button toolbar in the processing workspace then click External Controls.
Ensure that the external control that you want to link is visible by clicking on the tab for the type of your external control and make sure it is visible in the list.
In the Processing Workspace, locate the control that you want link to. In most cases, you will be linking to a control in the Processing Map. To access the controls on the processing block, open the block’s properties. You can also link to a remote device control in the Control palette.
Click on the link icon on the external control and drag it to the link icon of the other control.
When you drop the icon from the external control onto the icon of the second control, a dialog box appears asking if you want to create a new link. To create the link, select the Create New Link checkbox (if it is not selected already), provide a meaningful name for the link for easier identification later, and then click OK. The link icons on both controls turn purple, indicating the link has been established and is Active (the default state for a new control link).
Test the link. See Testing a Control Link.