Distance issue SmartThings motion sensor

Hi, I am pretty new to Smarthings and the forum. I bought my hub about a month ago and have added several devices, including GE in-wall switches, Hue lights and a SmartThings wall outlet. I am using Stringify and Alexa, mostly, to run things. So far, everything’s been great…until I bought the Samsung SmartThings motion sensor last night. This is the sensor: https://shop.smartthings.com/products/samsung-smartthings-motion-sensor It is driving me crazy. The distance on it is about 2 feet. And even at that, I have to wave my arms in front of it sometimes.

Here is what I am trying to do. I shall follow this section with a “what I have tried”section.
I have turned stairs that begin in an entry way. In the entry way is a Hue BR30 flood light (flush ceiling mounted.). At the top of the landing is a wall. I want to place the sensor on the wall so that it detects motion either coming up or going down the stairs. Because it’s turned stairs, the landing is between the flight from the 1st floor to the landing and the flight from the landing to the second floor. So, it’s pretty equidistant from either the top of the stairs or the bottom of the stairs. The light in t he entry way is bright enough to illuminate the entirely of the stairs when going up and down at night. Seems like a great use case. Doesn’t work well. The reason? I have to practically be on top of this sensor before it recognizes motion. I see that many people have mounted these above doorways. Frankly, I don’t see how, with the poor distance range os the sensor.

Here is what I have tried

  1. Moving the sensor from a distance of about three feet from the ground on the wall up to about 6 feet, and several spot in between.

  2. Moving the sensor more to the left and right sides of the wall at varying heights.

  3. Removing the sensor from SmartThings and re-pairing

  4. Placing the sensor on a table I have on the landing.

  5. Walking up and down and up and down and up and down the stairs, all the while monitoring the status of “motion” in the sensor. (Refreshing app every second)

  6. Testing in a simple Stringify flow to do nothing more than turn on the light when motion is detected.

Nothing seems to help. Until I am directly in front of or slightly to the right of the sensor, at NO MORE than approximately two feet away, motion is not detected.

Any help would be so greatly appreciated.

I have read a few threads on placement of sensors, as well, before bugging everyone with a new post.

Thank you in advance.

What sensor? Brand, model.
Be aware that most motion sensors have only about 120 deg field of view with 15-20 ft distance. Exception GE portable motion sensor with 180 deg field of view and 45 ft range

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It actually is the Samsung SmartThings motion sensor. Not the adt one. The square white one with the sensor in the corner. I do not see a model number o the box.

If I could get 15 ft distance out of this at 120 Deg angle, I’d be thrilled. As noted, I get about 2 ft, and usually need to be directly in front of it.

I’m not sure what thread you read about sensor placement, but if you are approaching the sensor straight on, it will have the shortest detection range. That’s because these PIR sensors detect very small values in heat passing across the sensor field. They can often be quite blind to something moving straight towards them. This is one of the reasons that people put them on the ceiling pointing down, then the person is crossing the field underneath.

The following FAQ might help (this is a clickable link)

Your landing case is a very difficult one when you only have one sensor as half of it will always be straight on unless, again, you put the sensor on the ceiling. And then it probably won’t catch people right at the beginning of the stairs going either direction, which won’t be what you want. It’s more likely that you will need one sensor at each end of the stairway.

But read the FAQ and see if it helps.

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FYI - The first generation SmartThings motion sensor worked great including with motion coming straight at it, mine picks up 25+ feet away reliably every night. The current generation however is just a step above worthless. When I bought one support said to mount it to the ceiling to have the best chance of picking up motion coming into a room. No way that would work for me.

Personally I’d return it for a refund and either find someone willing to sell a first gen or get a different motion sensor.

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The biggest issue with putting this on the ceileing would have been how very, very high up that ceiling is. Getting it up there is one thing, but that height would have put it at the high end of its stated range. Probably the GE sensor that the first responder had mentioned wold be a better option there.

Having read the threads on placement, I’d have to say the stairs are probably better served by either two typical sensors or by one higher distance sensor placed high.

On another note, further reading has me thinking this particular sensor is only suited to very small ranges (below its stated range.)

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A little reading on this particular model has me feeling you are spot on. Many folks have said their experience with this sensor has mirrored my experience when trying the sensor in a different application to see how it would do. I tried it in my kitchen, and noticed distance issues there, as well, despite trying various placements. The distance issues led to undesired behaviors. I have decided this is not the sensor for me, and will try again with something different.

Thanks to everyone for the responses. I appreciate everyone taking the time to help me out!

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What if you placed one at each end of the handrail and underneath the handrail so it would be less obvious. You might even be able to put it on the wall behind the handrail. It would still pick up some signal and the moving object would be moving across the field of view. In other words, even if it only picked up someone’s shoes, it would still activate. You could use custom rules to turn on lamps or whatever you wish to do with them.


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Yeah…this is one of the solutions I am considering when I circle back to this, maybe next weekend when time allows. I think it would work fine. Thanks!

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Did you ever resolve the issue? If not, I see a couple problems (I’m assuming by the photos, these are the latest generation ST motion sensors and not the 2015):

  1. as @JDRoberts noted, PIR sensors work best when an IR emitting source passes across the sensor field. So, you should actually be place the sensor more perpendicular to the entry point. So instead of the bottom and top of stairs head walls, you should be placing on the side walls or on a wall or ceiling which permits an IR emitting body to break pass across the sensor field, not straight on.

  2. one problem with your test, is that you are not taking into account the transmit time from motion sensor to hub to to light to trigger that event. The ST motion sensor also works on zigbee (2.4Ghz), so if there are interfering devices, etc., you might not get as quick of a response relaying the signal. Note that your other devices I am presuming are zwave devices, and a zigbee device does not operate on the zwave mesh network, so your other devices aren’t extending the mesh network to that zigbee device. The ST motion sensor, then, is on its own.

  3. Related to the test problem in point 2 is that your expectation of triggering the light is not realistic. You have a very short distance from sensor placement and stair entry. You are moving at a normal pace, so you probably won’t get the motion sensor to register motion, relay the signal to hub (zigbee), process zigbee to zwave, relay zwave signal to light to trigger on.

  4. You might also try disabling zigbee secure connect.

As far as what others report: I would almost bet that 90% of the people complaining about motion sensors simply do not understand how PIR sensors work. Even if you scan online videos of tech device reviewers, you will see a high number of them who do not understand how PIR sensors work.

I would recommend first trying the perpendicular mount outside of the stairway, but if in the stairway, then mount in the corners of the stairway or on the side wall at the entry points.

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Thank you so much for the follow up and excellent information regarding the functioning of PIR sensors. It is always helpful to learn more about how certain devices work!

I actually just got back around to the project within the last day or two, so good timing for me to respond with how it is going.

I ended up returning the sensor I had and purchasing another. This time, I purchased a Hue sensor (since the vast majority of my lighting is Hue.) But I did install the custom device handler I found here in the community so I could control it in ST and more easily tap into the other functionality this sensor provides. In the last two days, I have tested that sensor in a variety of scenarios, including the one that I was having trouble with in my original post. All scenarios tested are working as expected. Hue lights and GE switches (connected to non Hue lights) trigger within a good time frame, while I am still at the bottom or the top of the stairs. I know it looks like a super short distance from top and/bottom of stairs to where I had placed the sensor, but the image is a little deceiving. It’s a good 10 feet from either. The placement (same as used for the previous sensor) provides some pretty good angling from either top or bottom (depending on where I’m standing) as well as side, so there’s never a straight on view when the motion is expected to be captured. I was aware that the ST sensor is a zigbee device, and as I do have other zigbee devices in my set up, I figured it wouldn’t have had any issues.

At this point, as the new sensor works well, I am inclined to think that perhaps there were issues with that specific sensor, and that maybe a replacement ST sensor would have been fine. I am interested in purchasing more sensors, and may try another ST sensor to see how it goes.

Again, thank you for your follow up and information. It really is much appreciated that you took the time to provide it!