ALTA Carbon Monoxide Sensor Configuration and Installation Guide

Overview

The ALTA Wireless Carbon Monoxide Sensor uses an ultra-low power electrochemical transducer to measure CO. The sensor or meter measures the CO level in ambient air every five seconds and reports the most recent reading, along with temperature and the time-weighted average (TWA) of CO, on every user-configurable Heartbeat or when a threshold is breached.

The temperature measurement is used to compensate for temperature effects on the CO element. The sensor refreshes the TWA calculation every 15 minutes. If the sensor has been running for less than 7.5 hours, the TWA will be calculated based on the total time it has been running.

For temperature measurements, the sensor momentarily energizes a thermistor in series with a precision resistor. This produces a voltage proportional to temperature that the sensor converts into a digital temperature value. This measurement is then sent to the gateway, making the data available in iMonnit or another approved data service.

An ALTA CO 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 CO 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.
  • CO Instantaneous Concentration Threshold PPM—Values above this level will cause the sensor to enter the Aware State. CO Instantaneous Concentration 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. Or, the buffer prevents the sensor from bouncing between Standard Operation and Aware State when the assessments are very close to a threshold.
  • CO Time Weighted Average (TWA) Threshold PPM—Values above this level will cause the sensor to enter the Aware State.
  • 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

The ALTA CO Sensor uses Zero, Span, and Temperature Calibration. You can set your calibration standard by clicking the wrench or Calibrate icon in the upper right of the top menu in iMonnit.

Before calibrating the sensor, the meter must be connected to a gateway on the same network and in the same location.

Perform these steps in the order indicated.

  1. Zero Calibration: Click the Zero Calibration radio button. To perform Zero Calibration, click Calibrate. Keep the sensor in the 0 parts per million (PPM) environment and wait for a full two data points or readings to come in after this command is accepted (the red x on the status icon clears) for this process to complete. Don’t send any other calibration or configuration changes until this process is complete. After this step is complete, the sensor should read near 0 PPM.
  2. CO Span Calibration: This step calibrates the sensor according to a PPM reading above 100 PPM. It is recommended to calibrate the sensor in an environment with a CO concentration above the maximum expected in the environment you want to monitor. Click the Span Calibration radio button. This step is complete as soon as the red x clears.
  3. Temperature Calibration: Click the Temperature Calibration radio button. Enter the actual Temperature of your monitoring environment. Click the Calibrate button.

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 sensor. See this article for steps to start: Creating an iMonnit account.

Step 1.

Remove the sensor from the package.

Step 2.

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

Step 3.

Determine the sensor’s installation location. We recommend placing the sensor 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 sensor is communicating with the gateway, mount the sensor using the supplied screws or double-sided tape.

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