SmarThings Multi v2.0?

I was changing out a battery in one of my door mounted Muti’s a few days ago when that little light bulb in my head went off… and I started playing “what if”…

Like a lot of you, I have an existing wired alarm system in place. There is a door sensor from that system installed next to where I mounted my Multi. I was thinking that they both triggered by a separation of a magnet from the other side to indicate an “open” state. I remember that a few of us were posting about some how merging the current wired system in with the SmartThings system and then thought why not!

I don’t have the knowledge to do this but why not create a v2.0 Multi that has say… 2 wired input leads on one side of the multi and 2 wired output leads on the other. I could simply splice in to the wiring of the current wired system and I would then have each door working with my SmartThings system. I have no comment on the cosmetics, but it would work… wouldn’t it?

Obviously not the most grateful solution but I think you get the idea. The Multi v2.0 itself could even be installed on the wiring closet side of the wires, out of site from the door… back by the box where all the wires come together. Of course, the rest of the Multi’s features would be pointless because the temp wont move, the motion sensor wont move, etc… it would be nothing more than an Open/Close sensor. But I feel there may be a demand for something like this.


I believe what you are looking to do is already available with the Schalge zwave contact sensor. It has some terminals inside of it that you can connect an external wire to. It’s mentioned in a few of the reviews on Amazon:

Why not just use a plain open/close sensor?

The Schlage contact sensor has a pair of terminal screws which allow for connecting an auxiliary switch, as pointed out in this thread:

I have a few of these. The “external switch” feature is not advertised and it’s not documented, so you’re on your own. I haven’t tried it myself, but from visual inspection it looks like the terminal screws simply short circuit the reed switch.

The Schlage sensor is currently heavily discounted on Amazon, as part of the “Nexia Holiday Sale”.

@mweston: Beat me to it :wink:

This sounds exactly like what I am looking for. I think I’ll order one and play with it. If I can get it to work like I want then I’ll get a few more for the rest of the house. I like the idea of being about to interface my existing wiring in to my SmartThings world! I will keep you guys posted, and thanks for the info!

OK so I ordered one and it was delivered. It is true, there is a wiring block inside the sensor and it does work. I can cross the wires and the status shows Closed … separate the wires and the status shows Open. Now I just need to figure out how to make it work with my wired alarm system. I did screw the wires in on the board for “Zone 2”, the door to my garage. Only it didn’t work like I was hoping. Evidently it does not detect the change of state in the magnetic door sensor in my alarm system. I need to think about how it works and see what I can do.

In any event, I did order 2 more and will use them normally if I cant figure out how to interface them. The plus to me is I can choose to mount them with screws or double stick tape. The screws are a much better option in my case. I plan on moving the Multi’s that I have to other places.


I too have a wired security system that I pre-wired while my home was being built, over two years ago. I have yet to wire the sensors into the panel (DSC1832) and program it up. Your implementation of Schlage RS100HC V N N SL Home Door and Window Sensor is very interesting and I may want to experiment with them as you are.

Couple of questions for you:

  1. If I’m reading this right, you’re using the switch wires of your wired system to connect to the external switch contacts of the Schlage unit. In this way, your wired security system switches (magnetic, plungers etc.) can now be Z-Wave reportable. Is this correct so far?

  2. With the external contacts of the Schlage unit wired in parallel to your wired home security system zone, does the wired home security have any issue with the addd resistance of the Schlage unit? What I’m asking is, does the wired home security system for this altered zone still behave properly in that system?

In my home, I hard-wired every openable window and external door in a home-run fashion. Since I’ve yet to turn this system up, I too and thinking of wiring say, all my windows in a single room, together in series and then into a zone in the alarm panel AND in parallel to a Schlage unit. If that all works, I could do the same with all rooms. Doors I would still want to monitor individually.

Carl and others using these units, please weigh in with more detail on your experience with these Schlage units. Thanks.


My whole house is is prewired for contact sensors and I have an Arduino Centipede Shield (64 channel) that is itching to get stacked upon a SmartThings Shield to become a SmartThings Alarm System. I think that will be my next maker project. I need to do a couple of things first. 1) Find where the wires are aggragated exactly. I am told they are in a closet next to an outlet hmmmmmm. 2) Find where to get wired magnetic sensors that will fit in the 1/2 pre-drilled holes in my windows/door jams. Anyone know where to get this stuff?

The device type will be fund to code up for sure.



Looks like 3/8" holes are the current standard for flush, round, wired, mag switches. Though I found some 3/4" ones by Winn online. Still may work for you if you want to enlarge your holes.


Sorry for jumping in, but as far as I can tell, the wire terminals in Schlage RS100HC are for connecting external contractors, i.e. they are inputs, not outputs. I don’t think connecting them to your alarm system’s input terminals is a good idea because they are not galvanically isolated. That is, there’s voltage present on those terminals on both sides. The door sensor is a low-voltage battery powered device, while your alarm system is likely powered by 12V. There’s a chance you may damage your sensor if you do that. What you need is a dry contact (like a relay) that can sink whatever current that your alarm system drives through its input terminals which is typically ~ 5 mA when the contacts are open (no alarm) and ~ 50 mA when they’re closed (alarm condition).