Vaisala GMM220 User Manual

GMM220

Introduction

Vaisala GMM220 transmitter modules are versatile instruments for measuring CO2 in
industrial applications. The CARBOCAP® sensor is silicon based and its operation is
based on the NDIR Single-Beam Dual-Wavelength principle. The modules can be
configured for different CO2 measurement ranges and analog output ranges.

Figure 1 Dimensions of the Probes and Component Board of the GMM220

Series (in mm)

CO

Transmitter Modules

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The GMM220 module consists of a component board, cable and a CO2 probe. The
shorter probe model (GMP221) is for higher and the longer model (GMP222) for lower
CO2 concentrations. A waterproof connector connects the probe to the cable. The probe
also features a non-volatile memory for storing the calibration parameters. This enables
interchangeability of the probes and allows easy field calibration by exchanging the
probe with a freshly calibrated one.

Mounting

For power supply and analog outputs, the board is available either with pinheaders on
bottom side or with screw terminals on top side; serial interface has always a pinheader.

Figure 2 Dimensions of the Component Board (in mm)

If the board has pinheaders, mount it by soldering or plugging it into host board's female
connectors.

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Electrical Connections

Figure 3 Electrical Connections

Power supply:

Two supply voltage alternatives:

- +L 12 volt supply input (11 VDC - 20 VDC)

- +H 24 volt supply input (18 VDC - 30 VDC)

- GND common ground for power supply

Average current consumption is 100 mA (+ current output, max. 20 mA)

Analog outputs:

- 0 common for both analog outputs

- V voltage output (default 0-1 V, on request 0-2 V, 0-2.5 V or 0-5V)

- mA current output (default 4-20 mA, on request 0-20 mA)

Serial interface:

The interface is a 5 V (TTL) level full duplex serial port.

- GND signal ground (same potential as the supply GND)

- TX data transmitted by the CO2 module (low state corresponding mark)

- RX data received by the CO2 module (low state corresponding mark)

Leave other serial interface pins unconnected.

Probe wires: If the CO2 module is ordered with a separate probe cable, solder the wires

to the component board according to colors shown in Figure 3.

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