FAQ: (2017) Bought house with DSC alarm. How to connect all sensors to smartthings?


My house has a current DSC alarm system that I don’t use.
However it would be very nice to be able to connect all the hardwired sensors (doors, windows,…) to smartthings.

What do I need to do that?

I have done a little bit of research and it seems that other people use an arduino. Is this the preferred way to go, or are there better ways?

How many sensors does an arduino support?

Thank you


There are a number of project reports you can take a look at to see what other people have done. Use the quick browse lists in the community – created wiki and look on the “security” list. Just be aware that anything that refers to the smartthings brand thingshield will have to be done a little differently now because that device has been discontinued.


Here’s what I use. Pretty cool.


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Thanks for the plug, @TylerDurden! I am the developer of the project linked above. It sounds like a classic use case for you. I’m happy to help if you have any questions getting started.

In my opinion, using the NodeMCU ESP8266 instead of an Arduino is much simpler and cheaper.

There’s documentation here on Github: https://github.com/heythisisnate/nodemcu-smartthings

Thank you. Appreciate the answers.

You suggest going with the MCu instead of arduino. Would you think it is as reliable?

I was reading through the comments on your thread. Have you been able to solve the sensors being stuck in the wrong position?

It seems like you’ve done a pretty amazing job at putting it all together!
Any tip on the re-wiring? I’m guessing some are sensor wires, other are some kind of DSC signals. Is there an easy way to identify what to re-connect, what to leave alone?


I suggest an AlarmDecoder network appliance - full featured emulation, expandability, virtual zones, all sorts of cool stuff.

Use the existing alarm system to integrate into smart things, and take advantage of what the alarm itself gives you.

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I suggest you get an EVL4 and use the following integration. The device is about $100. You will keep your alarm system in tack and the integration works very well with a Raspberry Pi 3 or an always on PC. It’s really easy to setup but the instructions are all over the place. I love my little Pi and I have it running 4 different servers to serve my Home Automation System.

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Thank you for all the answers.

From the answers here, I see 3 solutions:

  • NodeMCU (remove DSC, rewire to new board)
  • AlarmDecoder (plug to DSC)
  • ELV4 (plug to DSC).

I have never used a DSC. I am under the understanding that its use would be redundant with Smartthings, wouldn’t it?
Would there be any advantage of having DSC + Smartthings running simultaneously?

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Do not rely on SmartThings for a Security System. Treat it more as a Home Automation Tool. There are too many things that could go wrong and you want to be assured that if someone tries to break into your house, then the police will be called and the alarm will go off.

Saying all of that. I have a DSC system and with the EVL4, I have access to 28 devices that I use with SmartThings. These range from Smoke and CO detectors to Door and Window Sensors, Motion Sensors and Glass Breaks Sensors. I can use my DSC panel to Arm SHM and visa-versa. For $100 bucks (the cost of the EVL4) I gained 28 devices! The Pi cost me about $40, because I had everything else I needed but I also use it for other things.

The NodeMCU, from my limited knowledge of it, disables the DSC system all together. The Alarm Decorder, works similar to the EVL4, it just cost more and a little more work.

The best thing is all 28 sensors are hard wired. Motion Sensors (4 of them for me) are instant. So instant that I had to make Virtual Motions to slow their actions down. Door and Window Sensors are instant. Smokes are instant.

Redundant? Not at all. Complimentary.


As the manufacturer of the AlarmDecoder I can tell you with fact that our device with the newest firmware is much more capable than the EVL-4. The ability to emulate zone expanders, long range radios, create virtual zones, fully program the alarm system without DLS (including all menus and sub menus) and much more. Add to that home automation capabilities, and it is a powerful device.

And it doesn’t really cost more when you factor in it comes with a Raspberry Pi, an sd card, power supply and case :slight_smile:

Also, define “more work” ?? You plug it into the alarm, network, power, and hit a webpage to set it up…

Sure, we also sell devices separately from the Appliance Bundle that you can DIY whatever you want, maybe that’s what you’re thinking?

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But is it working?

As @rontalley suggested, I’m also using DSC -> EVL-3(4) -> Alarmserver -> Smartthings and I’m very happy with it. You can use your alarm if you want and you have all zones available for ST. They just complement each other.
You do need a Raspberry Pi and EVL3 or EVL4.

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Right On. Didn’t mean to down play your device. With the Alarm Server, you just install the app in ST, define the config file, install the alarm server and and all of the devices populate. From there, you just use the devices in ST like any other device.

I am sure all the extra features your device offers, will be useful for many. It took me about 15 minutes to setup Alarm Server, after I understood the process.

Similar setup for our smartthings implementation, but no config files involved, everything is done through the UI once you install :slight_smile: 15 minutes sounds about right!


I can’t comment yet on the long-term reliability of it (I only started on this project in January this year) but I can say that I’ve been using it at my house with 100% reliability for a couple months since I worked out all the kinks. Yes, I’ve added some software features to solve the stuck in the wrong state problem.

My personal opinion (and I think I may be in the minority here) is no. In fact, I was in the same situation as you when I set out to create the NodeMCU-Smarthings project, my house had a built-in alarm that we never used. I think the usability of those DSC panel systems sucks. Who wants to type in a code every time they come or go? I put it to the wife-and-kids test … is my wife going to remember or care about arming the DSC alarm system every time she leaves the house with two kids to strap into car-seats? In my case, definitely not.

The best thing about a SmartThings-only alarm system is the full automation of it. This was my goal when setting out to build this project. Once it’s set up, you never have to do anything to arm or disarm the system. The wife and I both have the ST app on our phones set up as presence sensors, so the system arms and disarms automatically when we come and go.

Yes, the self-contained DSC system has an edge on reliability

Most of that big spool of wires coming out of your wall are going to the contact sensors throughout your house. It looks like your DSC system is pretty well labeled, those terminals labeled Z1, Z2, etc are the sensors for your zones and those are the wires you need to re-route to the NodeMCU. I can’t really tell from your pic which terminal controls the siren/alarm, but I’m sure you could figure it out.

Of course, one big advantage of the NodeMCU solution is the cost and simplicity. Assuming you already have a SmartThings hub and WiFi in your house, all you need is an $8 NodeMCU ESP8266 board (maybe a couple depending on the number of sensors you have), a $4 relay, and a few wires :wink:

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Well that’s why there is SmartThings integration - input your code once, use a button or proximity sensing :slight_smile:

Thanks all for the answers! I’m learning a lot in this thread.

I think I am leaning towards a DSC+bridge solution, such as:

  • AlarmDecoder
  • ELV-3 or ELV 4

It seems that it might save me quite a bit of set up time (nothing to rewire, and less that can go wrong).

For those who have a solution like that,

  • Is there any monthly fee? I’ve never used the DSC device. Can I use it outside of any subscription?
  • Are the ELV-3/4 / AlarmDecoder able to completely control the DSC?
    As in, once setup, will I ever have to physically use the DSC keypads for anything?

Thank you!

Since the posters in this topic have done such a good job of bringing together all the current information and discussing the details, I’ve made this an FAQ thread.

It will now show up on the quick browse lists in the community – created wiki.

Carry on. :sunglasses:

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With the AlarmDecoder Network Appliance you can create a completely self monitored solution with no 3rd party gateways or extra fees involved through the provided WebApp and SmartThings integrations. You also get full control of the alarm interface, with the ability to emulate zone expanders and create your own virtual zones. There is also full Long Range Radio and Contact ID support. You can also use the AlarmDecoder to program a DSC panel including all the menus and sub menus.

EVL-3/4 does not have these capabilities.

Yes, the AlarmDecoder can become your main keypad.

The hardest part will be resurrecting the alarm and getting the installer code to verify programming - which is doable.

This is why I decided to go with the NodeMCU solution as a replacement for the DSC. None of the simple tricks worked to get the installer code(s), and it looked like I’d have to hard reset the device and hope it wasn’t locked out by the installer after going through the trouble, not to mention reprogram all the zones, etc. It just got more intimidating the deeper I went.

If I had installer access to the DSC, I would consider a solution where ST is monitoring the DSC rather than replacing it. Mostly because ST relies on cloud connectivity to work. That’s a significant Achilles’ heel IMO. I’m also still trying to acclimate to using ST automation and ST’s SHM (Smart Home Monitor) as opposed to keypad arming/disarming. I still haven’t committed to ‘going live’ with the Siren for fear we will be accidentally setting it off too often because we forget the house is armed. I’m sure there is a way to configure ST to be friendlier about this, but I haven’t had time to play with it.

But back to why I chose to use the NodeMCU… since I had a ‘useless’ DSC sitting there with all those dormant sensors, replacing it with the NodeMCU / ST seemed better than nothing. And I’m quite pleased with the results. At this point I’d like to figure out an economical way to have backup internet so the solution can provide uninterrupted security more in line with the DSC. (barring any ST cloud issues). Fortunately, I’m not overly concerned about having tight security in this home, or I would have had a security company come in and replace the DSC to begin with.

Yeah, that’s why we built an unlocker module for our software - it works for most.