Multifunctional CO2 transmitters for building automation systems

CDT series air quality transmitters are engineered for building automation systems in the HVAC/R industry. The CDT series measures carbon dioxide (CO2) utilizing the industry standard NDIR measurement principle, and temperature (T). Optional relative humidity (rH) measurement is also available in the same device. CDT series devices are available with large touchscreen display making configuration of the device quick and easy.


The CDT2000 series transmitters calibrate themselves automatically using ABC logicTM. The ABC logicTM requires that the space in which the transmitter is used needs to to be unoccupied for four hours per day so that the indoor CO2 concentration drops to the outside level. CDT2000-DC is a dual channel model with a measuring channel and a reference channel that makes a continuous comparison and the necessary adjustment accordingly. CDT2000-DC is also suitable for buildings that are continuously occupied.


CDT series devices include:

• Separate field configurable output for each measurement parameter (CO2, rH, T)

• Proportional output options including: voltage (0–10 V, 2–10 V) and current (4–20 mA)

• Offset feature enabling field calibration for each measurement parameter (CO2, rH, T)

• Time extension button that enables boosting ventilation manually using the touchscreen display (models with relay)


CDT2000 series device options offer:

• 2” x 3” touchscreen display

• Field configurable relay for any of the three parameters

• Modbus configuration


See how easy it is to use the time extension mode:

Technical details

Accuracy: CO2: ±40 ppm + 3 % of reading, typical
DC model: 75 ppm or 10 % of reading (whichever is greater)
Temperature: <0.5 °C
Relative humidity: ±2…3 % rH at 0…50 °C and 10…90 % rH
Total error band includes accuracy, hysteresis and temperature effect over 5...50 °C and 10–90 % rH
Measurement elements: Temperature sensor: Pt1000 / Integrated (models with rH-measurement), Non Dispersive Infrared (NDIR) CO2 sensor, thermoset polymer capacitive sensing element for humidity
Measuring units: ppm, °C, % rH
Calibration: Automatic self-calibration, ABC LogicTM or continuous comparison (DC)
Supply voltage: 24 VDC/VAC ±10 %
Output signal 1: 0/2…10 V or 4…20 mA (linear to CO2) (2–10 V output: display required)
Optional output signal 2: 0/2…10 V or 4…20 mA (linear to rH) (2–10 V output: display required)
Output signal 3: 0/2…10 V or 4…20 mA (linear to Temp) (2–10 V output: display required)
Optional relay output: Potential free SPDT 250 VAC, 6 A / 30 VDC, 6 A with adjustable switching point and hysteresis
Operating temperature: 0...50°C
Protection standard: IP20




Product series

Carbon dioxide transmitter, analog outputs
Carbon dioxide transmitter, Modbus communication


ABC logic™, Automatic Background Calibration
Dual channel, for continuously occupied space


Wall mount


With relay
Without relay

Relative humidity sensor

With relative humidity sensor
Without relative humidity sensor


With display
Without display

Other Carbon dioxide transmitters: