All display controls must be tied to a Parameter.
For the control to populate with data during live scanning, or playback, that parameter must be backed by a Channel in the Channel Display.
That means, if you're display control is tied to "Engine Speed", you must have an "Engine Speed" parameter on the Channel Display.
If you tie your controls to Generic Sensors, your control will work with any Channel that acts as that particular sensor. This allows much more compatibility and portability with your controls.