SmartThings Community

Motion Sensor Light Activation Latency

(Mike DeRousse) #1

I working with a Smarthings motion sensor (latest model) and a Hue White bulb (directly connected to the ST hub / no Hue hub), and I have the following piston set up to turn on the light when motion is detected.

I’m not thrilled about the amount of time it takes the light to activate when I get in range of the sensor. Sometimes it can take 3 or 4 seconds.

Is this the best that can be expected? Or would it possibly be quicker to trigger this action with a different smart app? Any other ideas for reducing the latency?

FAQ: ST motion sensors is there more than 1 type (Includes manufacturer IDs)
(Dan) #2

If you’re using Hub v2, and your motion detector and lightbulb are running as local devices, then use the Smart Lighting native ST app, as it will also run locally on the v2 hub. This is as fast as it gets. Note, some motion detectors are inherently slow to report a status change.

( co-founder Terry @ActionTiles; GitHub: @cosmicpuppy) #3

If the sensor reports quickly (depends on model), then normal latency should sum up to under 2 seconds… So 3 or 4 seconds is bad, but not unexpected at times when the SmartThings Cloud is busy, or your piston is complex, or you have a slow broadband (ping…).

A huge reason we want the ability for more local processing…


The newest generation seems to be slower than previous versions. :disappointed_relieved:

@whoismoses has a video of this issue:

That said, to get the quickest response rate out of any zigbee motion sensor, try the following:

One) heal the zigbee network to make sure you’re getting maximum efficiency out of what you have. For zigbee, this is easy. Just take the hub off of power for at least 15 minutes (including removing batteries, if any) while leaving the other zigbee devices on power. This is long enough for all the other devices to go into “panic mode” because they can’t find the hub. After you power the hub up again, all the devices will rebuild their neighbor tables, finding the most efficient route. It can take a while for this process so you may not see efficiency improvements until the next day.

Two) as was suggested, move everything to smart lighting, using only local device type handlers, and see if that helps.

  1. check the physical placement of the device. Like all PIR motion sensors, this device is triggered by very slight changes in temperature moving across the detection field. Not straight on towards it. So you get the quickest response if the person will be moving at 90° to the sensor.
  1. if you’ve done all of the previous three, consider a test where you move the motion sensor about 25 feet from the hub, do another heal, and then test it there. If it’s noticeably quicker when it’s near the hub (after the heal) than it was in the original position, youmay need to add a zigbee repeater. Along the route from the hub to the motion sensor to help get the message through. Remember to do is it a heal after adding any new devices or moving devices to new locations. And make sure the motion sensor is at least 3 m from any Wi-Fi router or access point. Also, don’t put it right next to the hub to test. The zigbee antenna is Omni directional and the signal spreads as it moves away from the hub. So you should get the best test 15 to 25 feet from the hub, not right next to it.

But if you really have the 2016 model, it may just be slow. :scream:

Delays: ST and WebCore
(Mike DeRousse) #5

I appreciate all of the really helpful information guys. I’m going to give the Smart Lighting app a test to start off with, although I’m not sure the Hue light is running local. I’m using the Zigbee Hue White device handler with it. Is there a way to tell?


That particular device handler will not run locally, you can see the list that will at the topic previously linked to. But you should be able to find a generic zigbee dimmer DTH that will work for the test, probably the GE link. The only DTH is that will run locally at the present time are some of the ones that are officially published. No custom DTHs run locally.

You just need an on/off for the test. Then you can change it back to the other DTH. You’re just trying to isolate what factors are playing into the latency, and then once you know, you can decide what, if anything, you want to do about it.

1 Like
(Mike DeRousse) #7

You’re right, the GE Link DH is giving me local processing as demonstrated by the fact that the automation works with my hub disconnected from the network. Now I’m seeing about 1-2 seconds from motion to light; usually closer to 1. So that’s pretty good.

I’m surprised that the GE Link DH gives me on/off and dimming control just like the Zigbee Hue White DH did, so I guess I’ll start using that for all of my Hue White bulbs.

Thanks again.


Glad you saw some improvement!

BTW, The community-created wiki has the list of links you can check to see exactly which of your device type handlers are running locally. :sunglasses: