The CO
2
measurement is based on the Vaisala proprietary CARBOCAP
â
sensor, which uses a
novel, silicon-based microchip emitter instead of an incandescent light bulb. The internal
reference in the CO
2
sensor guarantees the best stability and operation also in constantly
occupied buildings without frequent readjustments.
CARBOCAP
â
sensors give correct CO
2
measurements immediately when powered on. As they
have a built-in reference measurement, they do not need a lengthy learning phase before the
measured values are correct. Proper operation can be verified immediately after snapping on
the device cover.
All GMW80 series transmitters measure carbon dioxide (CO
2
) and temperature (T) with the
exception of GMW87 and GMW88, which measure only CO
2
. Certain models also include
relative humidity (RH) measurement. Humidity measurement utilizes the Vaisala INTERCAP
â
sensor.
For measurements in more demanding conditions (for example, dusty or humid installation
locations), the GMW87 and GMW88 models provide an IP64-rated enclosure with a cable
gland. The GMW87 model can be accessed with the Modbus RTU protocol over an RS-485
interface. The communication settings for the protocol are entered with DIP switches on the
GMW87 component board.
GMW80 Series User Guide
M211748EN-G
8
