Visonic MCT-340E Magnetic Door/Window Sensor w/Temp On Sale

$14.99 with free first class shipping

Visonic 340

Use Classic App to pair. Provides temperature data. No screw terminals for hard wire but easy enough to solder onto ends of reed switch.


Use either app to pair

I couldn’t get the ST App to pair, just the Classic. I have some more of these coming so will try again and report back.

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The app is just a UI to tell the hub to pair the device. Shouldn’t matter which one. I ordered one, so will give it a try, too.

I bought a bunch of these a couple years back when they were on sale for $10/ea. Bought two more than I needed just to have extras. Just paired one of the spare ones using the new app out of curiosity. Put it in pairing mode, hit the scan button, and it showed up relatively quickly as a SmartSense Open/Closed Sensor.

FWIW these have performed flawlessly for the few years I’ve been using them. I really like them a lot. They have a much thinner profile than most other sensors, and the battery life has been fantastic. The ones on the two doors that get constant use go through a battery in 10-12 months, but the ones on windows that don’t get opened and closed often lasted just over 2 years on a single battery.


I bought a couple at $15, but then bought another 10 when they went to $10. I’ve also had a great experience with them. I painted all of mine black to blend in with my trim. I bought and installed mine in November of '17 and I’ve only had to replace the batteries in 3-4 of them so far. Fantastic!

Just received some more 340Es and tried again to pair using the ST App - no luck - just sits there scanning then times out and I tried refresh several times. I ran the Classic App and it paired immediately so I have something going on with the new ST App not finding anything in pairing mode (I have a v3 Hub). Also tried a Bosch Motion Detector received in same order with same result - no pairing with new ST App and immediate pairing with Classic App. Strange… guess I’ll just keep using Classic for pairing.

I’ve been successfully using the classic app with these no problem but whenever I click on the sensor in the new app, it says can’t connect to device. I don’t mine using classic app but I heard that soon samsung will force migration.

Are you guys having the same problem i’m having?

Are you using a custom device handler? That might cause the issue you’re seeing.

I just use the built in device handler and am able to open I’m the new app just fine.

Built into what, ST itself? I bought a dozen or so a few years ago at around $10 as well and at the time a custom device handler was required. I had no real issues getting them recognized. I do have 2 annoying issues with them. I wonder if it’s because of the non-standard device handler and maybe I should delete it and repair everything natively:

  1. battery life shows 11% or 1% in multiple devices. I’ve found that if I remove the battery (a week or 2 ago) and put it back in, it pops up to 33 or so. Back down to 11 as we speak. Something is amiss with battery health.
  2. ST notifies me a few times a day that the battery is low, even though I’ve turned off device health. Not sure how to suppress these messages since I have a Webcore piston notify me at 5% but just once a week. At 11%, the battery will still last weeks or months so daily notifications is idiotic.

Login to IDE at

  • click on the menu choice My Devices
  • select your visonic sensor
  • click Edit at the bottom
  • in the Type field, change the device handler to SmartSense Open/Closed Sensor
  • click Update at the bottom of the screen
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Looks like I was wrong about custom handler and in fact my devices are all SmartSense Open/Closed Sensor. Issues identified above are with standard handler.

The battery issue is common. Looks like they are working on adding a three tier battery warning system with the warning levels determined by the DTH instead of a fixed % for all devices.

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