9
Logging
Data
Once the GasLab® software has been installed and the meter is connected to the computer, you can
gather data in a variety of ways. Depending on the type of meter, data can be collected in real time,
data logs can be downloaded from the meter’s memory (if equipped), and saved to the computer,
and data can be reviewed on the meter’s LCD display (if equipped).
For
each
logging
session
1.
Turn the meter ON.
2.
The meter must be started at least 1 minute prior to deployment and data logging to allow
the CO2 sensor time to warm‐up and calibrate.
3.
Set the logging interval (min 30 sec) as desired and commence logging.
4.
When data logging is completed, turn the meter OFF.
Setting
the
Logging
Interval
To change the default settings, connect the meter to a computer using the included USB cable. Select
the desired meter, and change the settings.
NOTE:
Refer to the GasLab® User’s Manual for complete instructions.
Display
and
Alarm
(CM
‐
0016,
CM
‐
0017
only)
This data logging meter includes a built‐in audible (80dB) alarm and an LCD (Liquid Crystal
Display) display that provides visual indication of the current CO2 level by changing color to green,
yellow or red, depending on CO2 level ranges selected. The display will change colors depending on
the actual CO2 level readings by setting the “Green”, “Yellow”, and “Red” ranges.
The alarm is set per LEED IAQ levels by default but can be programmed to other standards such as
OSHA levels using the GasLab® software. The new alarm level will be maintained in the meter’s
memory.
During operation, when the meter is turned on, and when the high concentration CO2 level
programmed is reached, an 80dB alarm will sound. The alarm can be muted for 30 seconds by
pressing the button on the front of the meter. This feature can be changed in GasLab®.
Calibration
The CO2 sensor, in IAQ applications only, uses an algorithm called Automatic Background
Calibration (ABC) to ensure maximum accuracy by continuously adjusting the zero‐point.
The ABC algorithm allows the CO2 sensor to dynamically shift its CO2 reading by a constant. It
works via storing the lowest CO2 sample taken over the ABC Period and assuming that this low
value is equal to a known value (the target value). It then adjusts the output of the CO2 reading by
the delta between these values. This algorithm does not affect the linearization of the output signal.
For example, by default ABC is enabled with an ABC Period of 180 hours, a target value of 400ppm,
and a maximum delta of 30ppm. This operates under the principle that ambient, outdoor air is at
400ppm.
