Series CDTA Communicating Carbon Dioxide Detector

Brand: Dwyer Instruments, LLC

The Series CDTA Communicating Carbon Dioxide Detector combines the function of three room sensors into a single, compact housing. 

Parameters include carbon dioxide, humidity, temperature, and temperature set point with override. By having field selectable Modbus® and BACnet Communications, only four wires are needed for power and the communication signal. The communicating detectors can be daisy chained together to further reduce installation cost. 

In order to reduce the set up time, the RS-485 MAC address is set up using on board dip switches. A second set of dip switches are used to select whether output is Modbus® RTU or BACnet MS/TP communication protocols and to limit access to the set up menu.

Like our Series CDT Carbon Dioxide Transmitter, the Series CDTA uses a Single Beam Dual Wavelength Non-Dispersive Infrared (NDIR) sensor to measure the carbon dioxide level. This technology can be used in installations that will be occupied 24 hours per day. 

For improved accuracy, the transmitter can be field calibrated to the environmental conditions of the installation. Also, the barometric pressure can be programmed to correct for altitude. The humidity uses a capacitive polymer sensor and the temperature is measured using a 10 KΩ thermistor sensor.

The humidity sensor is field replaceable without the need for additional calibration. Optional local and remote displays are available to display any of the parameters.

For applications in which the building occupants aren't familiar with CO2 concentrations, the LCD can be programmed to display temperature, humidity, or temperature set point instead.
  • Digital intelligent temperature compensation algorithm (DITCA™) corrects for errors due to self heating effects of combination wall sensors
  • Field Selectable Modbus® and BACnet Communications Reduces Wiring
  • Single Beam Dual Wavelength CO2 Sensor
  • Replaceable Humidity/Temperature Sensor
  • Physical Hardware Lockout
  • Optional Remote Display Tool



  • ± 1° C (± 1.8° F) at 25° C
  • ± 2 % - RH
  • ± 3 % of Reading ± 40 ppm

Approvals & Certifications

  • LEED
  • FC Factory Calibration Certificate
  • BTL
  • CE


  • BACnet MSTP
  • Modbus RTU


  • 0.5 W - Average
  • 1.2 W - Peak


  • LCD Display

Flow Rate

  • 0 to 2000 ppm
  • 0 to 5000 ppm - CO₂


  • 0 to 100 % Relative Humidity
  • 10 to 95 % Relative Humidity, Non-Condensing


  • Wall Mounted


  • 2-Wire RS-485

Power Requirement

  • 10-30 Vac
  • 10-42 Vdc

Response Time

  • 2 minutes for 99 % Step Change

Sensor / Probe Material

  • Capacitive Polymer - Humidity

Sensor / Probe Type

  • Thermistor

Temperature Range

  • 0° to 50° C (32° to 122° F)

  • Demand control ventilation in schools, office buildings, hospitals, and other indoor environments
  • LEED® certification
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