Setting Inactivity Alert Times

Setting Inactivity Alert Time for Sensors


The Inactivity time for your Inactivity Action is an important consideration in avoiding being alerted when your sensor is not actually inactive.

Inactivity time is counted by the iMonnit software. Because there may be delay in when the iMonnit software receives sensor readings as a result of the communication chain (Sensor Heartbeat > Gateway Heartbeat > iMonnit software), it is important to set your Inactivity Time duration such that it takes into account both the heartbeat of the sensor as well as the heartbeat of the getaway. A simple calculation will keep false alarms to a minimum.

Inactivity Time formula

When monitoring inactivity, we suggest setting the duration to twice the heartbeat of the sensor plus one heartbeat of the gateway plus one additional minute. (For a reference explaining Heartbeats, refer to this article)

Inactivity Duration = (SensorHB x 2) + (GatewayHB + 1 minute)

For example, if your sensor Heartbeat is 60 minutes, and that sensor is checking in with a gateway with a Heartbeat of 5 minutes, the minimum time to which you would want to configure the Inactivity Time would be 126 minutes. This is figured with the Inactivity Time formula.

Inactivity Duration = (SensorHB x 2) + (GatewayHB + 1)

126 min = (60 x 2) + (5 + 1)

Troubleshooting an Inactivity alert

When you receive an inactivity alert, a small investigation may take you to the root cause for the alarm.

First determine which device triggered the Inactivity alert; the sensor name should be listed in the alert itself.

  1. Log into your account on, and look for the device that triggered the notification to verify that it is still offline.
  2. If the sensor is not offline, check the settings in the inactivity notification. Make certain the time period set for the inactivity alert is (two times the heartbeat of the sensor) plus (one heartbeat of the gateway + 1 minute) as described above.

If just this device is offline:

In “Overview”, check the last time the sensor checked in; note the date and time. Then look at the signal strength. If it is poor, that could be the cause. Next, look at the battery level. If it is low, that could be the cause.

If neither the signal strength nor battery level is low, then consider this: was this sensor talking to a repeater? If so, check to see if the repeater is still online. Check the repeater’s data to see if it’s handling messages or if there are failures and messages in the queue. If no repeater was used, check the gateway. Is it working properly?

If ALL your sensors are offline:

Most likely the problem is not with the sensors but with a link up the line. Start with the gateway. Is the gateway on and checking in? If it is a cell gateway check that the cell network is live. For an Ethernet gateway, check to see that internet access is available. If you have the USB gateway, check that the gateway application utility status is “Active”.

You can also check if there is an issue with Monnit’s servers by viewing the page.

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