With the remotes, there are 2 types of operation.
1. If you press the remote 'Close', for less than a second, the flaps close fully from open, likewise, a short press of 'Open', opens them fully from closed.
2. If you press for more than one second, then let go the button, it will open or close by a small amount, press again and its opens or closes a bit more. To be honest, its a bit fiddly at first. The best way is to connect up the units and play with them off the car, to best understand the different types of operation. As far as I know, the full 'Open to Close and Close to Open' option, is only available with the remote controls. But the step option is available both on the dashboard button and the remotes.
The two units operate as one, obviously, time them both to be either fully open or closed before operating them together.
There was a wiring fault with my control box, which resulted in having to power both motors from the one outlet. It was not a big deal however.
Pat.