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CO2, humidity and temperature room sensor · BACnet points list
Dwyer Series CDTA / CDTC Communicating CO2 Detector BACnet points list
Updated 7 November 2026
The CDTA and CDTC are wall-mount CO2 detectors with temperature, a setpoint and an override button; the CDTA adds humidity. A DIP switch selects BACnet MS/TP or Modbus RTU. On BACnet the device is an application specific controller (B-ASC) with three analog inputs for the measurements, analog values for setpoints, calculated psychrometrics and calibration offsets, and two binary values.
This page lists 16 BACnet objects for the Dwyer Series CDTA / CDTC Communicating CO2 Detector — 10 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from Dwyer’s own free documentation, linked below.
- Manufacturer
- Dwyer
- Model
- Series CDTA / CDTC Communicating CO2 Detector
- Equipment
- CO2, humidity and temperature room sensor
- Equipment type
- Thermostats, sensors & meters
- BACnet objects
- 16 (10 writable)
- Transport
- BACnet MS/TP
- Firmware
- Application 1.6, firmware 1.5
- Default device instance
- 607000 + MAC address (607xxx)
- Also known as
- CDTA, CDTC, CDTA-2N000, CDTA-5N000, CDTC-2N000, CDTC-5N000, CDTA-2N000-LCD
Reference only, provided as-is: verify against Dwyer’s current documentation and the live device before use. Not official Dwyer information. Terms of use.
BMS integration notes: Dwyer Series CDTA / CDTC Communicating CO2 Detector
Read CO2 (AI 1), humidity (AI 2, CDTA) and temperature (AI 3). Read or write the setpoint AV 1 and watch BV 1 for the occupant override.
Minimum points to map
The short list most integrators start with — enough to run the unit from a BMS. Map more as the job needs.
| Object | Name | Why | Access |
|---|---|---|---|
| AV 1 | Set Point | Temperature setpoint | Write |
| AI 1 | CO2 Concentration | CO2 level, ppm | Read |
| AI 2 | Relative Humidity | Space relative humidity (CDTA only) | Read |
| AI 3 | Temperature | Space temperature | Read |
| BV 1 | Override | Occupant override | Write |
Network setup
- DIP switch SW2 sets the MAC address (factory 127); a second DIP switch selects BACnet MS/TP instead of Modbus RTU and can lock the setup menu.
- MS/TP master at 9600, 19200, 38400, 57600, 76800 or 115200 baud.
- Default device instance is 607xxx where xxx is the MAC address.
Watch out for
- Barometric pressure (AV 9) is writable; set it for the site.
Dwyer Series CDTA / CDTC Communicating CO2 Detector BACnet objects
Type: AI, AO, AV, BI, BO, BV, MI/MO/MV (multi-state) · Access: Read read-only, Write writable, Command writable with a priority array.
| Description | States | |||||
|---|---|---|---|---|---|---|
| AImin | 1 | CO2 Concentration | Range depends on model (2000 or 5000 ppm) | ppm | Read | |
| AImin | 2 | Relative Humidity | CDTA only | %RH | Read | |
| AImin | 3 | Temperature | °C or °F | °F | Read | |
| AVmin | 1 | Set Point | Temperature setpoint, 0-50 °C | °F | Write | |
| AV | 2 | Set Point Low Limit | 0-50 °C | °F | Write | |
| AV | 3 | Set Point High Limit | 0-50 °C | °F | Write | |
| AV | 4 | Dew Point | Calculated | °F | Read | |
| AV | 5 | Wet Bulb | Calculated | °F | Read | |
| AV | 6 | Specific Enthalpy | kJ/kg or BTU/lb dry air | BTU/lb | Read | |
| AV | 7 | Display Mode | Integer values 0-7 | Write | ||
| AV | 8 | CO2 Offset | ±500 ppm | ppm | Write | |
| AV | 9 | Barometric Pressure | Site barometric pressure, 677-1016 hPa | hPa | Write | |
| AV | 10 | Relative Humidity Offset | ±30 % in 0.1 % steps | %RH | Write | |
| AV | 11 | Temperature Offset | ±30° in 0.1° steps | °F | Write | |
| BVmin | 1 | Override | Setpoint override | Write | ||
| BV | 2 | Use SI Units | Write | 0=US customary units, 1=SI units |
No points match these filters.
Object ID lookup: Dwyer Series CDTA / CDTC Communicating CO2 Detector point IDs by name
Integration notes
- The object list comes from the PICS object table; writable objects are those with Present_Value in the writable-properties column.
- Relative humidity (AI 2) and the humidity-derived values (AV 4-6, AV 10) apply to the CDTA; the CDTC has no humidity sensor (Dwyer product manual).
- Temperature units follow BV 2 Use SI Units.
- DIP switch details in the setup notes come from Dwyer's CDTA/CDTC installation manual, not the PICS.
Check it against the live device. A points list tells you what the controller can expose; the unit in front of you may differ by firmware or installed options. This list is provided as-is for reference only and may contain mistakes — confirming it before you write, map or commission anything is up to you (terms). Easy BACnet scans a network for BACnet IP devices from an Android phone, reads every object on the Series CDTA / CDTC Communicating CO2 Detector and exports what it actually has to Excel — free. New to BACnet? Start with what a BACnet points list is and what the object types mean.
Questions about the Dwyer Series CDTA / CDTC Communicating CO2 Detector
How many BACnet points does the Dwyer Series CDTA / CDTC Communicating CO2 Detector have?
This list has 16 BACnet objects: 3 analog inputs, 11 analog values, 2 binary values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which Dwyer Series CDTA / CDTC Communicating CO2 Detector BACnet points are writable?
10 of the 16 objects accept a write. Points marked Command have a priority array: a write holds until it is released, so release it back to automatic when you are done.
Where is the official Dwyer Series CDTA / CDTC Communicating CO2 Detector BACnet documentation?
The source is Series CDTA and CDTC Communicating Carbon Dioxide Detector - BACnet Protocol Implementation Conformance Statement (Bulletin AQ-CDTA-CDTC-PIC), revision 2013-12-18, published free by Dwyer at https://assets.dwyeromega.com/manuals-do/CDTA_BAC_CDTC_BACnet_Conformance.pdf.
What are the minimum BACnet points to integrate the Dwyer Series CDTA / CDTC Communicating CO2 Detector?
Start with AV 1 Set Point (Temperature setpoint); AI 1 CO2 Concentration (CO2 level, ppm); AI 2 Relative Humidity (Space relative humidity (CDTA only)); AI 3 Temperature (Space temperature); BV 1 Override (Occupant override).
How do I check these points on the real Series CDTA / CDTC Communicating CO2 Detector?
Scan the network with a BACnet IP browser such as Easy BACnet, open the device and compare its object list with this table. Anything missing is usually an option that isn't installed or a point that is disabled in the controller's configuration.
More Dwyer BACnet points lists
- Airflow velocity sensor
Dwyer Series AVLV low air velocity transmitter, BACnet MS/TP
Dwyer Series AVLV low air velocity transmitters (100-400 FPM ranges) with the BACnet MS/TP option.
Also known as: AVLV, Series AVLV, AVLV BACnet, DwyerOmega AVLV, P-AVLV-B - Duct airflow velocity sensor
Dwyer Series AVPT pencil-style air velocity transmitter, BACnet MS/TP
Dwyer Series AVPT thermal-anemometer duct velocity transmitters ordered with the BACnet MS/TP output.
Also known as: AVPT, Series AVPT, AVPT BACnet, DwyerOmega AVPT, AVPT pencil style air velocity transmitter - Differential pressure sensor / controller
Dwyer Series DHC Digihelic differential pressure controller, BACnet MS/TP
Dwyer Series DHC Digihelic panel-mount differential pressure controllers with two relays, analog outputs and RS-485 set to BACnet MS/TP.
Also known as: DHC, Series DHC, Digihelic, Digihelic DHC, DwyerOmega DHC, DHC-xxx-xxx - CO / NO2 gas sensor
Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP
Dwyer Series GSTC carbon monoxide (GSTC-C) and nitrogen dioxide (GSTC-N) gas transmitters with switch-selectable BACnet MS/TP or Modbus RTU.
Also known as: GSTC, GSTC-C, GSTC-N, Series GSTC, DwyerOmega GSTC, CO Detector, NO2 Detector - Insertion electromagnetic BTU / energy meter
Dwyer Series IEFB insertion thermal energy meter, BACnet MS/TP
Dwyer Series IEFB insertion electromagnetic flow meters with inlet/outlet RTDs that calculate thermal energy, on BACnet MS/TP or Modbus RTU.
Also known as: IEFB, Series IEFB, IEFB BTU meter, DwyerOmega IEFB, Series IEF energy meter, F-IEFB - Differential pressure and airflow sensor
Dwyer Series MS2 Magnesense II Differential Pressure Transmitter with BACnet (MS2-B)
Dwyer Series MS2 Magnesense II differential pressure transmitters with BACnet MS/TP (ranges up to 25 in. w.c.).
Also known as: MS2-B, MS2, Magnesense II, P-MS2-B - Differential pressure sensor / transmitter
Dwyer Series MSX-Comms Magnesense Pressure Transmitter
Dwyer Series MSX-Comms Magnesense differential pressure transmitters with BACnet MS/TP or Modbus RTU output.
Also known as: MSX, MSX-Comms, Magnesense MSX, DwyerOmega MSX, MSX BACnet - Humidity and temperature sensor
Dwyer Series RHPX humidity/temperature communicating transmitter, BACnet MS/TP
Dwyer Series RHPX duct, space and outdoor humidity/temperature transmitters with the BACnet MS/TP / Modbus RTU communication option.
Also known as: RHPX, Series RHPX, RHPX Comms, RHPX BACnet, DwyerOmega RHPX, AQ-RHPX-C - Room pressure monitor
Dwyer Series RSME / RSMC Room Status Monitor
Dwyer Series RSME/RSMC room status monitors (built-in differential pressure plus universal and external BACnet inputs) for isolation rooms, labs and cleanrooms.
Also known as: RSME, RSMC, Series RSME, Series RSMC, DwyerOmega RSME, Dwyer room pressure monitor - Ultrasonic BTU / energy meter
Dwyer Series TUF ultrasonic energy meter, BACnet MS/TP (TUF-B)
Dwyer Series TUF ultrasonic heating/cooling energy meters (TUF-150 to TUF-2000) ordered with BACnet MS/TP.
Also known as: TUF, TUF-B, TUF BACnet, Dwyer TUF BTU meter, DwyerOmega TUF
Source: Series CDTA and CDTC Communicating Carbon Dioxide Detector - BACnet Protocol Implementation Conformance Statement · Bulletin AQ-CDTA-CDTC-PIC · rev. 2013-12-18. Object names, instances and units are reproduced as published; descriptions are our own.