Arrival sensors failing after a few days

General Discussion
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We’ve been trying out a simple configuration of the V2 hub, an arrival sensor and two multi-purpose sensors in about 8 different locations. Except in two locations, we’ve found that the arrival sensor fails to operate properly after about a week or so.

The failure is that the state gets reported as “not present” even though the sensor is very much in the home and within feet of the hub. Removing and replacing the battery in the Arrival sensor fixes the problem (for another week or two). In some cases, we have had to go through the pairing process again for the sensor.

To try to understand the failure mechanism better I’ve set up a Zigbee sniffer with the TI CC2531EMK USB dongle and the Ubiqua sniffer software.

This was very helpful to understand the normal operation of the Arrival sensor but unfortunately did not shed any light on the failure as the failed sensors were not transmitting anything. After removing and replacing the battery, they did start sending Beacon Requests sequentially on all channels.

We believe we’ve followed the deployment best practices detailed in this forum and elsewhere - separating the AP and the hub by several feet, ensuring insecure rejoin is enabled, etc.

It’s not clear exactly how the Wi-Fi interference causes the failure - can someone shed any light? Even if the channel was busy or there was receiver de-sense one would thing eventually a ZigBee Rejoin would go through. What we’re seeing seems to imply a sensor firmware crash but of course we have no way to verify this.

One other factor - the locations where we see the failures have Xfinity gateways (with Wi-Fi APs) whereas in the two locations where the arrival sensors have worked without issues we have older 802.11n conventional APs.

I would appreciate any hints about how we can understand what’s going on here and how we improve the reliability of the Arrival sensors.

Thanks!

1 Like
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great detail - thanks.

in general, add repeaters to improve the mesh, but I think you moved the sensors very close to the hub which should make this irrelevant.

Did you prove the board had power from the battery (BEFORE you reseated the battery?) . I suspect corrosion something dropping supply voltage. Just a guess - there lots of anecdotal problems with the arrival/presence sensors.

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I could be wrong, but I seem to remember someone more knowledgeable than myself saying that the arrival sensor has a preferred repeater to which it reports.

In any event, it should not be necessary to store the sensor near the hub when home.
For me, with fresh batteries the presence sensors do their job perfectly for about a month. Then lo and behold… the routines they trigger start firing when the sensor is home, sometimes in rapid-fire fashion. So somehow, the system is sporadically losing the ability to detect the sensor’s pulse.

I love the concept of presence for this system.
It just is routinely problematic, whichever way you approach it.

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Thanks for your replies. We’ll check the power connections on the next failed sensor.

The first level of triage we need is to see if these failures are related to Wi-Fi/Zigbee coexistence or whether the sensors themselves have some inherent unreliability. If we can force the failure with strong Wi-Fi interference and catch a trace of the failure moment that may shed some light.

Maybe we’ll also swap out the sensors that haven’t failed with the ones that have failed. That may tell us if the environment has an effect. With just a handful of devices, it will be tough to come to a strong conclusion but let’s see.