Humidity Sensor Offsets and Rule Condition Triggers and Charts

ALTA Humidity Sensors with firmware 14.x (or later) support calibration saved to the sensor’s memory. 

All Generation 1 Humidity Sensors and ALTA Humidity Sensors with firmware version 14.x and prior do not support calibration saved to the sensor firmware

Any calibration offsets applied to these earlier sensors only support an Offset as applied to the software. Rules are triggered based on the value reported by the sensor at the sensor level, not the value displayed in iMonnit that applies the offset. 

Therefore, you may see the reading displayed accurately from the user’s perspective in iMonnit but find the Rule is being triggered by a value that does not include the applied offset.

To trigger Rules based on the Calibrated/Offset value entered using the Calibrate feature, you will need a newer ALTA Sensor running firmware version 14.x or later. Older sensors will not trigger Rules based on the Calibrated/Offset value.

When this comes into question

If you receive a notification from a Humidity sensor that you suspect may not be triggered from the applied Calibration/Offset:

  1. Check the version of the sensor:
  • Log into iMonnit.
  • Select Sensors on the Overview bar.
  • Select the appropriate Network.
  • Find and select the Humidity Sensor you are reviewing.
  • Navigate to the sensor's Settings tab ("Gear" icon).
  • In the Sensor Info section, look for RadioBand to include ALTA. Look for the firmware version; the below example is a sensor running firmware version

If you do not see the word ALTA, you have a Generation 1 sensor, and your sensor will not trigger Rules based on the Calibrated/Offset value.

If the firmware is 14.x.x.x or earlier, your sensor will not trigger Rules based on the Calibrated/Offset value.

If your sensor is a previous version, you can review the data that triggered the Rule.

  1. Export the sensor Readings and review the raw data.
  • Log into iMonnit.
  • Select Sensors.
  • Select the appropriate Network.
  • Select the sensor.
  • Select the History tab.
  • Set the date for the desired time period.
  • Select the cloud-download icon to export the data to CSV.

  • Look for the Raw Data column of the CSV file for the reading delivered directly from the sensor. If a software Offset is applied, you will find a different value in the Raw Data column versus the Value/Formatted Value columns.

The Raw Data will contain the reading reported at the sensor level. The Value/Formatted Value column will contain the Calibrated/Offset value applied through the portal.


With the older Humidity Sensors, Charts are based on the raw data value. 

Therefore, you may also see a discrepancy in the value displayed in the Chart (which used the raw data value) and the Sensor Readings (which applies the Offset in the software).

Differences in iMonnit in the Sensors’ Calibrate Tab

In newer ALTA sensors with firmware version 14.x (or later), the Calibrate tab will display a Humidity and Temperature Offset rather than entering the Actual Reading. 

In these fields, you would enter the difference between the reading of the Monnit Sensor and your reference. Save. The Offset will be applied upon the sensor’s subsequent check-in. 

For example, if your sensor reading was 20°C, and your reference read 18°C, you would enter “-2” and click Save. The subsequent check-in of the sensor would accept the -2°C offset.

In earlier Gen1 and ALTA Sensors with firmware prior to 14.x, the Calibrate tab will display fields to enter the Actual Reading values.

In these fields, you would enter the value of your reference. Save. The calibration will be applied to the software immediately.

After entering calibration

In newer sensors, the calibration is accepted on the sensor’s subsequent check-in (just as most Monnit Sensors operate). However, with the older sensors, the Calibration/Offset is applied immediately to the software. Therefore, you can review the readings as shown in the Readings tab of the sensor, and the Offset will immediately affect the readings (including the history).


Improvements in the Monnit hardware and firmware allowed Monnit to include the ability to apply offsets to current Humidity Sensors. 

Although this is not retro-compatible, the ability to support this on older sensors is made possible by improvements in our software. 

With this article, you can successfully operate with Calibration/Offsets.

Feel free to contact with further inquiries.

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