Sorry to revive an old thread, but I have a similar scenario with an “XOX” horizontal window where the two outer panes open towards the middle. I was hoping to cover both operable panes with one Monoprice/GoControl sensor and another N.O. sensor wired to the external contacts. However, this doesn’t quite do what I want. If both windows are opened, and then only one of them is closed, then the sensor will report “closed”, which wouldn’t be a good thing! After watching the video above of the guy with the Vera controller, it seems I would need 2 external N.O. sensors wired in series, right? Or am I missing something obvious?