I have a roll-off skylight with a reversible 110 AC motor. Currently it is wired to a 3PDT center-off switch. I would like to have X10 control (one code for open, one code for close) with auto shutoff and a rain sensor for auto close. Where do I start? I'm thinking I need an intelligent controller to handle interlocking, some magnetic sensors and a bunch of relays.

I'm not really sure but I'll bet the guy at www.Cocoontech.com can answer your question.

-Martin
Martin@AutomatedOutlet.com

Tell me more about the mechanism. The switch's middle detent is your only way of stopping the motor currently when it's travel is fully extended? I have (5) skylights that operate with 24 volt dc and from what I can gather sense a current spike to stop the motor. I at first used a timer for opening and a reed switch for sensing closed status. When the Velux stuff started popping up on Ebay I finally aquired all I needed to go propriatary. I think you can devise a self-supervising relay reversing scheme to make sure that you don't short your AC. I remember seeing a circuit with dual contactors that made it physically impossible for the motor to see both forward and reverse phasing at the same time. Would a mechanical clutch be feasible so a simple timer would work for motor stop?

Right -- the center off position of the switch is the only way to stop the motor. It also ensures that the motor cannot be reversed before being stopped. When the switch is thrown one way, the hot run wire is energized and the start wires are polarized one way; when thrown in the opposite direction, the hot run wire is again energized but the start wires are polarized the opposite way, which causes the motor to start in the other rotation. All switching is of the 120V operating current.

I'm thinking of using a couple of X10 low-voltage relays to receive Forward and Reverse commands. A high-voltage DPDT relay controls the polarity of the start wires and an SPDT relay controls current to the DPDT and the run wire. The DPDT is set for normal Forward; when tripped by the X10 Reverse relay it switches to the Reverse configuration. Somehow I need to get both X10 relays to trip the SPDT relay so current will be supplied when either X10 gets an "ON" command, but I haven't figured that out yet. Another problem is that it would be possible to trip the DPDT to Reverse while it is already operating in Open.

For auto shutoff, I was thinking of using the Leviton Dry Contract Transmitter momentary version and a two closure magnets on the frame with one traveling magnet on the skylight. The Leviton can be configured to send an "OFF" command on closure and no command on opening, so it can send the appropriate "OFF" when the skylight reaches either travel limit.

I built a slot car layout for a customer once that motored down suspended from a ceiling in the basement. Got a lot of stuff from Grainger as far as motors, limit switches, pulleys, ect. Unless you have some kind of clutch (like modern day overhead doors do) I certainly wouldn't want to rely on X10 for motor stop. The limit switches I used were actually full motor current rated so you could use them as back up fail safes. X-10 is still a little flakey, I use it exclusively everywhere (all my switch locations are 6400/16400 transmitters) and sometimes there is other bus traffic either from my HA controller or another person pressing a transmitter somewhere. Most of the time they'll re-transmit but you can't count on it. Idec has their mini PLC's now that are easily programmed for local appliance type control, might be just the thing for your app. Check out thier smart relay [Link: idec.com]