Key facts
- Brand
- Vaisala
- Model
- GMM220
- Industry
- Industrial
- Documents
- 2
- Languages
- EN · DE
- Last added
- 2012-04-06
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Vaisala GMM220 User Guide
The GMM220 series are CO₂ transmitter modules that use a silicon‑based CARBOCAP® NDIR sensor. They are available with two probe types (GMP221 for higher concentrations and GMP222 for lower concentrations) and support analog voltage/current outputs as well as a serial interface for data acquisition.
The guide covers mechanical mounting, electrical connections, LED status indicators, serial command protocol, pressure and temperature compensation settings, technical specifications, compliance information, warranty, accessories and support procedures.
Vaisala GMM220 specifications
| CO₂ measuring range (GMM221) | 0–10,000 ppm |
|---|---|
| CO₂ measuring range (GMM222) | 0–20 % vol |
| Accuracy | ±1.5 % of range + 2 % of reading |
| Power supply | 11–20 VDC or 18–30 VDC |
| Humidity range | 0–100 % RH (non‑condensing) |
| Analog output resolution | 12 bits |
| Average current consumption | 100 mA |
Source: Vaisala GMM220 User Guide
All Vaisala GMM220 documents by type
Day-to-day operation, settings and troubleshooting. Start here if the product is already set up.
Questions answered in these manuals
What serial port settings are required for communication?
Set the serial port to 9600 baud, 8 data bits, 1 stop bit, no parity and no flow control.
How can I change the CO₂ concentration output format?
Use the DISP command with option 2 for ppm or option 4 for percent; for continuous output use MF_MODE with the same options.
What do the LEDs on the module indicate?
In normal operation the red LED is off and the green LED blinks continuously; if both LEDs blink, the module is in error state and no analog signal is output.
Which command displays the CO concentration in ppm?
Send the command `DISP 2` followed by carriage return; the module replies with the CO concentration in ppm.