Understand Sensor Heartbeats, Aware States, Assessments, and Rearm

Monnit Sensor operation is based on a concept called the Aware State. This term refers to the sensor's operating state that allows a condition to be reported immediately when it is detected.

A few settings allow this operation to occur. This article will outline them.

Event Sensors vs. Interval Sensors

Two types of sensor radio behaviors are associated with Monnit Sensors. First, there are event sensors that respond immediately to an event as it occurs (think of event sensors as yes/no data).

Second, there are interval or reading-type sensors that work on a timed basis. They wake up at set intervals, gather data, transmit the data, and then go back to sleep until the next interval.

Examples of Event Sensors

  • Water Detection
  • Door/Window
  • Motion
  • Dry Contact

Examples of Interval (Reading) Sensors

  • Temperature
  • Humidity
  • Voltage
  • Pressure

Heartbeat

A free Basic iMonnit subscription requires 120 minutes of minimum Heartbeats. To achieve a more frequent minimum Heartbeat of 10 minutes using iMonnit, a paid iMonnit Premiere subscription is required. iMonnit Premiere also includes Advanced Sensor Settings, such as Aware State Heartbeats and Assessments, which aren't available to iMonnit Basic accounts.

Monnit Sensors are battery-operated and are designed to efficiently use battery power. Since sensor radio hardware consumes significant power, part of this design includes the strategic radio transmission of sensor readings.

Rather than streaming data through the sensor’s radio, which would rapidly deplete the sensor batteries, Monnit Sensors transmit readings to their gateway in intervals called Heartbeats. The default Heartbeat for sensors when they are assembled is 120 minutes, but this is configurable.

Every sensor has a Heartbeat regardless of the type of radio behavior.

  • Event sensors use the Heartbeat function to tell the system that they're still active and will report the current sensor state, signal strength, and battery status.
  • Reading sensors use the Heartbeat as their set interval for gathering and sending information.

Aware State

To immediately transmit an Aware reading, the gateway must have the On Aware Messages setting (also known as Force Transmit on Aware) set to Trigger Heartbeat (set to On). This is what allows the gateway to transmit Aware readings immediately to iMonnit. This setting is enabled by default.

The Aware State of Monnit Sensors allows a sensor reading to be transmitted to iMonnit immediately when a preconfigured condition is detected. Since Monnit Sensors are often used to monitor for events that require immediate detection, an Aware State reading allows this to occur.

Every sensor has an Aware State function. The Aware State allows the sensor to function at a higher level when certain conditions are met.

For event-type sensors, the detection of an event automatically triggers the Aware State. For reading-type sensors, the user sets the conditions that must be met for a sensor to enter its Aware State (also used for Assessments per Heartbeat). Once in the Aware State, the sensor will operate based on the Aware State settings.

Setting the Aware State Heartbeat to a quicker interval allows the user to receive more frequent sensor information and/or notifications until the sensor reports a condition that is back in the normal operation range. Also, messages flagged as Aware, cause the gateway to communicate to the server immediately. Standard (unaware) messages are queued on the gateway until the next gateway Heartbeat (default gateway settings).

Assessments per Heartbeat

Reading-type sensors also support Assessments per Heartbeat, where the sensor wakes up, gathers data, and compares it against conditions set for the Aware State. If conditions are met, the sensor sends that information to the software immediately (otherwise, the sensor goes back to sleep)

The more frequently your sensor takes Assessments, the more responsively the sensor can detect an Aware condition, transmit an Aware reading, enter its Aware State, and start checking in with the Aware State Heartbeat frequency.

If an Assessment does not meet the triggering condition for an Aware Message, it is discarded. Assessments cannot be converted to data points (except for the occasion in which they trigger an Aware State Heartbeat).

Time to Rearm

Time to Re-Arm allows the user to define how long an event-type sensor should take before it is allowed to detect another event.

For example, if a motion sensor detects movement, setting a Rearm time of one second allows the sensor to detect movement again in just one second.

This can allow the user to capture more frequent information if desired, but it also uses more battery. Setting a Rearm time of 10 minutes preserves battery life but will not capture information again until the sensor is re-armed.

Examples of How the Aware State Works

With the sensor configurations, set as shown below:

  • Heartbeat Interval: 120 Minutes

  • Aware State Heartbeat: 30 Minutes

  • Assessments per Heartbeat: 2 (every 60 minutes)

  • Aware State threshold: 257°F

  • Scale: Fahrenheit

1:00 PM -> 38°F

Sensor wakes and assesses the current conditions. The temperature read is under the threshold, not Aware, sensor transmits current temperature of 38°F. Sensor begins the countdown to 60 minutes for the next assessment to be taken and 120 minutes for the next Heartbeat. The sensor goes to sleep.

2:00 PM -> 60°F

Sensor wakes and assesses the current conditions. The temperature read is under the threshold, not Aware; the sensor transmits a current temperature of 38°F. The sensor begins the countdown to 60 minutes for the next assessment to be taken and 120 minutes for the next Heartbeat. The sensor goes to sleep.

3:00 PM -> 200°F

Sensor wakes and assesses the current conditions. The temperature read is under the threshold, not Aware. The sensor transmits its current temperature of 200°F as it is time for the next Heartbeat. The sensor begins the countdown to 60 minutes for the next assessment, and then it goes to sleep.

3:20 PM-> 258°F

As the sensor is asleep, there will be no action until 60 minutes after the last Heartbeat or until the next assessment, which is 60 minutes after the last assessment.

4:00 PM-> 258°F

Sensor wakes and assesses the current conditions. The temperature read is over the threshold, and the sensor enters the Aware State. The sensor transmits the data to the gateway with an urgent tag which tells the gateway to send the data to the server immediately. The Heartbeat is now set to 30 minutes, and the assessments are twice within that Heartbeat, or every 15 minutes. The sensor goes to sleep.

4:15 PM-> 262°F

Sensor wakes and assesses the current conditions. The temperature read is over the threshold, is in the Aware State. The sensor does NOT transmit the data as this was only an assessment, not a Heartbeat. The sensor begins the countdown to 15 minutes for the next assessment, then goes to sleep.

4:30 PM-> 262°F

Sensor wakes and assesses the current conditions. When the temperature read is over the threshold, and the sensor goes into the Aware State. The sensor transmits the data to the gateway with an urgent tag, which tells the gateway to send it to the server immediately. The sensor sets the Heartbeat countdown to 30 and the assessment countdown to 15 minutes.

4:45 PM PM-> 258°F

Sensor wakes and assesses the current conditions. The temperature read is over the threshold, is in the Aware State. The sensor does not transmit the data as this was only an assessment, not a Heartbeat. The sensor begins the countdown to 15 minutes for the next assessment and then goes to sleep.

5:00 PM -> 258°F

Sensor wakes and assesses the current conditions. The temperature read is over the threshold, and the sensor remains the Aware State. The sensor transmits the data to the gateway with an “urgent” tag which tells the gateway to send the data to the server immediately. The sensor sets the Heartbeat countdown to 30 and the assessment countdown to 15 minutes. The sensor goes to sleep.

5:15 PM -> 256°F

Sensor wakes and assesses the current conditions. The temperature read is under the threshold. The sensor has left the Aware State. It does NOT transmit the data as this was only an assessment, not a Heartbeat. The sensor continues the countdown to the next Heartbeat and then goes to sleep.

5:30 PM

Sensor wakes and assesses the current conditions. The temperature read is under the threshold, and the sensor is not Aware. The sensor transmits the data to the gateway. The sensor sets the Heartbeat countdown to 120 and the assessment countdown to 60 minutes. The sensor then goes to sleep.

Conclusion

Understanding a sensor's Heartbeat, Aware State, Assessments, and Time to Rearm operation is critical for efficient battery operation, considering the need for timely sensor readings and the number of required data points. If you have inquiries regarding these unique operational configurations, contact Monnit Support.

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