iMonnit Heartbeats Explained

What are Heartbeats?

Monnit sensors transmit data in set intervals called Heartbeats. Heartbeat is a term Monnit uses to describe the interval in minutes of how frequently the sensor communicates a sensor reading with a gateway if no exception (Aware State) activity is detected during an assessment. The default Heartbeat for a sensor is 120 minutes (2 hours), but is configurable to as frequent as 10 minutes with an iMonnit Premiere subscription. Heartbeats can be configured to be even more frequent when using a locally hosted version of Monnit software (Express, Enterprise, MINE).

Assessments Per Heartbeat

Assessments Per Heartbeat operate in tandem with sensor Heartbeats and Aware State Heartbeats. Sensors only transmit data on scheduled Heartbeats, but can take Assessments (sample readings) in between Heartbeats to check if the configured Aware State Threshold has been breached. If the Aware State Threshold is determined to have been breached, the sensor will wake up, transmit the reading to the gateway, and start checking in with the Aware State Heartbeat frequency.

Gateway Heartbeats

Gateways also have Heartbeats. Gateway Heartbeat default configuration varies by gateway type. This means sensors transmit data to the gateways on the sensor’s Heartbeat, the gateway queues the data, and it is transmitted by the gateway to the iMonnit software on the gateway’s heartbeat. This means that there may potentially be a delay between the time the sensor takes a reading on its heartbeat, and the time that data is transmitted to the iMonnit software by the gateway. This is why it is good practice to have the gateway’s Heartbeat set to at least more frequent than the most frequent sensor Heartbeat on the Sensor Network.

Default Heartbeat configurations for gateways are as follows:

Ethernet Gateway: 5 minutes

4G LTE Gateway: 15 minutes

3G Cellular Gateway: 60 minutes

2G Cellular Gateway: 60 minutes

Wireless Sensor Adapter: 5 minutes

Serial MODBUS Gateways: do not have heartbeats

Gateway Force Transmit on Aware setting

Monnit gateways have a default setting which enables the gateway to immediately transmit sensor readings to the iMonnit software which are Aware State readings. This means that if a sensor enters its Aware State, the reading immediately triggers a gateway Heartbeat to the iMonnit software prior to the scheduled gateway Heartbeat. This is a core feature which allows for an exception state detected by the sensor to be entered into the software immediately when the sensor transmits the Aware State reading.

Editing Sensor Heartbeats and Assessments Per Heartbeat

  1. Select Sensors in the left-hand sidebar.
  2. Select the network to which the sensor has been added.
  3. Select one of your sensors.
  4. Select the settings tab (gear icon).
  5. Enter the desired configuration (in minutes) in the the Heartbeat field.
  6. Enter the desired configuration in the Aware State Heartbeat field (Aware State Heartbeats are generally more frequent than standard Heartbeats).
  7. Enter the desired configured for Assessments Per Heartbeat.
  8. Click Save.

How it works

• Heartbeat Interval: 120 Minutes

• Aware State Heartbeat: 30 Minutes

• Assessments per Heartbeat: 2 (every 60 minutes)

• Aware State threshold: 257°F

• Scale: Fahrenheit.

In this example, we will use a temperature sensor with the following configurations:

Standard Heartbeat: 120 minutes

Aware State Heartbeat: 30 minutes

Assessments per Heartbeat: 2 (every 60 minutes)

Aware State Threshold: 257 degrees 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 does NOT transmit the data as this was only an assessment, not a heartbeat, it goes back to sleep. Sensor begins the countdown to 60 minutes for the next assessment to be taken and continues the 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. Sensor transmits current temperature of 200°F as it is time for the next heartbeat. Sensor begins the countdown to 60 minutes for the next assessment to be taken. The sensor goes to sleep.

3:20 PM-> 258°F

As sensor is asleep, there will be no action until 60 minutes after the last heartbeat or until the next assessment 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 withing 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. Sensor begins the countdown to 15 minutes for the next assessment to be taken. The sensor goes to sleep.

4:30 PM-> 262°F

Sensor wakes and assesses the current conditions. 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 the data 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. Sensor begins the countdown to 15 minutes for the next assessment to be taken. The sensor 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. The sensor 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 goes to sleep.

Conclusion

A heartbeat is the increment of time in minutes a sensor transmits readings to the gateway on current conditions. This data is then queued by the gateway and sent to the iMonnit software on the gateway’s heartbeat unless (by default) the reading transmit to the gateway is an Aware State reading. Heartbeats allow for efficient battery usage and enable a sensor to provide readings on exception states immediately. For further inquiries on this, feel free to contact Monnit Support.

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