ALTA Carbon Dioxide Configuration and Installation Guide

Overview

The ALTA Wireless Carbon Dioxide Sensor uses a low-power, high-performance carbon dioxide (CO₂) sensing element to measure the amount of CO2 (0–10,000 ppm) in ambient air and report instantaneous and time-weighted average (TWA) readings.

The ALTA Wireless Carbon Dioxide Sensor measures the CO₂level in the air using a non-dispersive infrared (NDIR) sensing element. It reports data from every user-configurable Heartbeat (report interval) from the most recent measurement. This measurement is then sent to the gateway, making the data available in iMonnit or other approved data services.

The sensor or meter produces TWA data by accumulating eight hours of instantaneous CO₂ readings and averaging them together. An ALTA CO₂ Meter can be calibrated and auto-calibrated for improved accuracy. For more information about the operation of ALTA Sensors, see the ALTA General Information Guide.

Settings to Configure

The settings below are specific to the ALTA CO₂ Sensor.

Sensor Name—A unique sensor name to easily identify it in many in-app views and notifications.
Heartbeat Interval (Minutes)—The expected time between communication from the device to the gateway while in the Normal State and the absence of any data-triggering events.
Aware State Heartbeat (Minutes)—The expected time between communication from the device to the gateway while in the Aware State.
CO₂ Instantaneous Threshold PPM—Values above this level will cause the sensor to enter the Aware State.
CO₂ Instantaneous Buffer PPM—A value between measurements corresponding to a sensor in an Aware State and those corresponding to a sensor in the Normal State. This stops the device from cycling between states when measuring near the maximum or the minimum limits.
CO₂ Time Weighted Average (TWA) Threshold PPM—Values above this level will cause the sensor to enter the Aware State.
CO₂ Time Weighted Average (TWA) Buffer PPM—After exceeding a threshold and entering the Aware State, the Normal State will not resume until the measurement value is an Aware State Buffer value away from either threshold.

Example: if the CO₂ TWA Threshold is set to 1000 PPM and the buffer is 50 PPM, once the sensor assesses 1000 PPM or greater, it will remain in an Aware State until dropping to 950 PPM.

Measurement Interval—How often the meter measures.
Synchronize Off (Default)—The next report will occur one Heartbeat after the last report time. This allows the sensor to self-optimize network traffic patterns and reduce congestion.
Synchronize On—Aligns the next report with UTC (Global) time, regardless of the last report time. This allows multiple sensors to generate reports in a synchronized manner. Aware State Transitions will still report on a threshold breach, but the following report will return to the next aligned report interval.

Warning: Too many synchronized reports will increase network congestion. We recommend that no more than 10 devices per gateway be synchronized.

Example: The Heartbeat is configured to 60 minutes, and the device reports at 1:47 PM.

If Synchronization is Off, the subsequent reports are expected at 2:47 PM, then at 3:47 PM.

If Synchronization is On, the subsequent reports are expected at 2:00 PM and 3:00 PM.

Calibrate

Auto calibration settings include:

Enable Auto Calibration
Auto Calibration Interval Days

The ALTA CO₂ Sensor uses Altitude or Fresh Air Calibration. You can set your calibration standard by clicking the wrench or Calibrate icon in the upper right of the top menu in iMonnit.

The Altitude Calibration must be performed before Fresh Air Calibration. Altitude and Fresh Air Calibration should be performed in the same environment and at the same altitude. Before calibrating the sensor, the meter must be connected to a gateway on the same network/location.

Altitude Calibration—The meter will compensate for pressure differences based on altitude.
- Select the Altitude Calibration radio button.
- Enter the current altitude or elevation of the sensor in feet to set the Altitude Calibration.
- Press the Calibrate button.
- Wait for two data points to come in after this command is accepted (red x on status icon clears) for this process to complete.
- Do not send any other calibration or configuration changes during this period.
Fresh Air Calibration—Calibrates the sensor based on a previously measured point or your input and creates an offset to adjust the sensor to a known actual value.
- Press the Calibrate button.
- Keep the sensor in a fresh air environment and wait for a full two data points to come in after this command is accepted (red x on status icon clears) for this process to complete.
- Do not send any other calibration or configuration changes before this process completes.
- The sensor must be in an outside fresh air environment for 15 minutes before performing this step. After this step is complete, the sensor should read near 400 ppm.

Installation Steps

If this is your first time setting up your Monnit system, you must set up your iMonnit account and connect your ALTA Gateway to iMonnit before registering your meter. See this article for steps to start: Creating an iMonnit account.

Step 1.

Remove the meter from the package.

Step 2.

Register the meter in iMonnit. Do not install the batteries until told to do so in iMonnit. Refer to this walk-through guide and configure the meter’s Settings and Scale information in iMonnit for your specific application or use case.

Step 3.

Determine the pressure meter’s installation location. We recommend placing the meter in the location and ensuring it reports to the gateway before final installation. See this article if you’re using an ALTA Site Survey Tool to perform a site survey to determine sensor installation location.

Step 4.

After ensuring that the meter is communicating with the gateway, mount the sensor using the supplied screws or double-sided tape.