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Sentinel Circle Mode vs. Sentinel Gate Mode

Summary​

Every sensor can work in one of two directions. Wi-Fi and Bluetooth sensors default to Safe Circle Mode but can be switched. Email, Notification and Sentinel Area sensors always work in Sentinel Gate Mode.

Details​

Sentinel Circle Mode (default)​

Use this when the person should normally be nearby. The alert fires when the device can no longer be detected. This is the usual choice for monitoring someone at home.

  • To set this up: choose "Trigger when absent" in the sensor editor. Sentinel Circle then watches for the device to disappear.
  • Example: a Wi-Fi sensor watches your home network. When this phone can no longer see it, you're alerted.

Sentinel Gate Mode​

Use this when the person should NOT normally be nearby. The alert fires the instant the device is detected. Useful for spotting an unexpected arrival or entry.

  • To set this up: choose "Trigger when detected" in the Wi-Fi or Bluetooth sensor editor. Sentinel Circle then watches for the device to appear.
  • Example: a Bluetooth beacon at a building entrance. When the person's device comes into range, you're alerted that they've arrived. Email, Notification and Sentinel Area sensors always work this way — they alert when an email, a notification, or an unrecognized device arrives.

Tip: Email, Notification and Sentinel Area sensors are always Sentinel Gate Mode because they react to something arriving (an email, a notification, an unrecognized device), not to something disappearing. For Wi-Fi and Bluetooth: Sentinel Circle Mode alerts on disappearance, Sentinel Gate Mode alerts on appearance.

Which device moves?​

A radio can only prove that this phone and the watched device are no longer within range of each other. It cannot tell which of the two actually moved — the beacon may have left, or this phone may have left while the beacon stayed put. Place this phone where the safe area is, and keep the watched device with the person.