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CO2 sensor / transmitter · BACnet points list
Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) BACnet points list
Updated 6 November 2026
The CDD3 is a Greystone CO2 transmitter with native BACnet MS/TP. It reports CO2 and, when fitted, RH, temperature and a setpoint adjust value as Analog Inputs, with Analog and Binary Values for relay setup, calibration offsets and units. Objects for options that are not installed stay in the list but report a fault.
This page lists 19 BACnet objects for the Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) — 13 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from Greystone Energy Systems’s own free documentation, linked below.
- Manufacturer
- Greystone Energy Systems
- Model
- CDD3 Series CO2 transmitter (BACnet MS/TP)
- Equipment
- CO2 sensor / transmitter
- Equipment type
- Thermostats, sensors & meters
- BACnet objects
- 19 (13 writable)
- Transport
- BACnet MS/TP
- Firmware
- 1.0 (PICS, April 21, 2022)
- Default device instance
- 381003
- Also known as
- CDD3, CDD3A1XXXBAC, CDD3 BACnet, Greystone CDD3 CO2
Reference only, provided as-is: verify against Greystone Energy Systems’s current documentation and the live device before use. Not official Greystone Energy Systems information. Terms of use.
BMS integration notes: Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP)
Give each sensor a unique MS/TP MAC and device instance from the menu, then read CO2 (AI 1) and any fitted RH and temperature inputs. The relay setpoint and offsets are setup values.
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 |
|---|---|---|---|
| AI 1 | CO2 Value | Space CO2, ppm | Read |
| AI 2 | RH Value | Space RH (RH option) | Read |
| AI 3 | Temperature Value | Space temperature (temperature option) | Read |
| BI 1 | Relay Status | CO2 relay energized | Read |
Network setup
- Default MS/TP MAC address is 3 and default baud is 9600; both are set in the Setup menu.
- Device instance defaults to 381000 + MAC (381003); it stops following the MAC once written over BACnet.
- Lower Max_Master from 127 to the highest MAC on the segment to cut token-passing overhead.
Watch out for
- Objects for options that are not fitted report Reliability NO_SENSOR and Event_State FAULT; do not poll them.
- The sensor updates about every 4 s; poll every 5-10 s, not faster.
Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) 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 Value | CO2 reading, 0-10,000 ppm | ppm | Read | |
| AImin | 2 | RH Value | Relative humidity (RH option) | %RH | Read | |
| AImin | 3 | Temperature Value | Temperature (temperature option); units follow BV 1 | °F / °C | Read | |
| AI | 4 | Setpoint Value | Local setpoint adjust value (setpoint option) | % | Read | |
| AV | 1 | Relay Setpoint | CO2 relay trip point, 500-1500 ppm (default 1000) | ppm | Write | |
| AV | 2 | Relay Hysteresis | Relay hysteresis, 25-200 ppm (default 50) | ppm | Write | |
| AV | 3 | Relay ON Delay | Relay on delay, 0-255 s (default 15) | s | Write | |
| AV | 4 | Temperature Offset | Temperature calibration offset (default 0) | delta °C / °F | Write | |
| AV | 5 | RH Offset | RH calibration offset, -10 to 10 %RH | %RH | Write | |
| AV | 6 | Altitude | Installed altitude, 0-2550 m in 50 m steps | m | Write | |
| BV | 1 | Temperature Units | Temperature unit select | Write | 0=°C, 1=°F | |
| BV | 2 | Auto Cal Enable | CO2 automatic calibration (default enabled) | Write | 0=Disable, 1=Enable | |
| BV | 3 | Relay Test | Forces the relay for testing | Write | 0=Relay off, 1=Relay on | |
| BV | 4 | Override Test | Override on/off (object page name: Override Operation) | Write | 0=Off, 1=On | |
| BImin | 1 | Relay Status | CO2 relay energized | Read | 0=Inactivated, 1=Activated | |
| BI | 2 | Override Status | Override active | Read | 0=Inactivated, 1=Activated | |
| MV | 1 | LCD Backlight | LCD backlight mode (default Auto) | Write | 0=AUTO, 1=OFF, 2=ON | |
| MV | 2 | Display Modes | Values shown on the LCD | Write | 0=CO2, 1=CO2+RH, 2=CO2+T, 3=CO2+RH+T | |
| MV | 3 | Setpoint Modes | Setpoint adjust scale (default %) | Write | 0=%, 1=°C1, 2=°C2, 3=°F1, 4=°F2, 5=%RH, 6=ppm |
No points match these filters.
Object ID lookup: Greystone Energy Systems CDD3 Series CO2 transmitter point IDs by name
AI1CO2 ValueAI2RH ValueAI3Temperature ValueAI4Setpoint ValueAV1Relay SetpointAV2Relay HysteresisAV3Relay ON DelayAV4Temperature OffsetAV5RH OffsetAV6AltitudeBV1Temperature UnitsBV2Auto Cal EnableBV3Relay TestBV4Override TestBI1Relay StatusBI2Override StatusMV1LCD BacklightMV2Display ModesMV3Setpoint Modes
Integration notes
- Points from the object summary table and per-object pages of the setup guide.
- AI 2, AI 3 and AI 4 exist only with the RH, temperature and setpoint options; the relay objects need the relay option.
- Multistate objects are Multi-State Values (MSV) in the guide; listed here as MV.
- The summary table calls BV 4 "Override Test"; its object page prints the name "Override Operation".
- Access from the PICS: Present_Value is writable on AV, BV and MSV objects.
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 CDD3 Series CO2 transmitter (BACnet MS/TP) 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 Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP)
How many BACnet points does the Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) have?
This list has 19 BACnet objects: 4 analog inputs, 6 analog values, 2 binary inputs, 4 binary values, 3 multi-state values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) BACnet points are writable?
13 of the 19 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 Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP) BACnet documentation?
The source is CDD3 Series Carbon Dioxide Transmitter - Setup Guide BACnet Communication (SG-CDD3A1XXXBAC-003), revision 2022-04-21 (PICS date), published free by Greystone Energy Systems at https://downloads.greystoneenergy.com/SG/SG-CDD3A1XXXBAC-003.pdf.
What are the minimum BACnet points to integrate the Greystone Energy Systems CDD3 Series CO2 transmitter (BACnet MS/TP)?
Start with AI 1 CO2 Value (Space CO2, ppm); AI 2 RH Value (Space RH (RH option)); AI 3 Temperature Value (Space temperature (temperature option)); BI 1 Relay Status (CO2 relay energized).
How do I check these points on the real CDD3 Series CO2 transmitter (BACnet MS/TP)?
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 Greystone Energy Systems BACnet points lists
- CO2 / RH / temperature sensor
Greystone Energy Systems CHT Series CO2 / RH / temperature sensor (BACnet MS/TP)
Greystone CHT series combined CO2, humidity and temperature sensors with the BACnet MS/TP output.
Also known as: CHT, CHTDT, CHTXXXBAC, Greystone CHT - Carbon monoxide (CO) gas sensor / transmitter
Greystone Energy Systems CMD Series CO transmitter (BACnet MS/TP)
Greystone CMD series carbon monoxide transmitters (model name CMD5B) with BACnet MS/TP, with optional relays, buzzer and temperature.
Also known as: CMD, CMD5B, CMDXXXBAC, Greystone CMD carbon monoxide - Room temperature / RH / differential pressure monitor
Greystone Energy Systems CR3 Series cleanroom monitor (BACnet MS/TP)
Greystone CR3 series cleanroom and critical-room monitors measuring temperature, humidity and room differential pressure, with BACnet MS/TP.
Also known as: CR3, CR3XXXBAC, CR3C, Greystone CR3 critical room monitor - Room dewpoint / humidity sensor
Greystone Energy Systems DPRC Series room dewpoint transmitter (BACnet MS/TP)
Greystone DPRC series room dewpoint transmitters (PICS model DPRCB) with BACnet MS/TP.
Also known as: DPRC, DPRCB, DPRCXXXBAC, Greystone room dewpoint sensor - Duct / outdoor dewpoint and humidity sensor
Greystone Energy Systems DW Series duct / outside air dewpoint transmitter (BACnet MS/TP)
Greystone DW series duct and outside-air dewpoint transmitters (PICS models DPDDB and DPODB) and HTX2 high-accuracy RH/T transmitters with BACnet MS/TP.
Also known as: DW, DPDDB, DPODB, DWXXXBAC, Greystone duct dewpoint sensor, HTX2, HTX2XXXBAC, Greystone HTX2 high accuracy humidity transmitter - Gas detector / sensor (CO and NO2)
Greystone Energy Systems GDT Series toxic gas detector, CO / NO2 (BACnet MS/TP)
Greystone GDT series toxic gas detectors with CO and/or NO2 sensors, relays, buzzer and strobe, using BACnet MS/TP (typical for parking garages).
Also known as: GDT, GDTXXXBAC, GS, Greystone CO NO2 gas detector, parking garage gas detector - Greenhouse CO2 / RH / temperature sensor
Greystone Energy Systems GH Series horticulture sensor (BACnet MS/TP)
Greystone GH series horticulture (greenhouse / grow room) sensors measuring temperature, humidity and CO2, with BACnet MS/TP.
Also known as: GH, GHXXXBAC, Greystone greenhouse CO2 RH temperature sensor - Greenhouse CO2 sensor
Greystone Energy Systems GO3 Series horticulture CO2 sensor (BACnet MS/TP)
Greystone GO3 series horticulture CO2 sensors (0-20,000 ppm) with optional temperature, RH and relay, using BACnet MS/TP.
Also known as: GO3, GO3 BACnet, Greystone GO3 greenhouse CO2 - Humidity / temperature sensor
Greystone Energy Systems HN Series humidity / temperature transmitter (BACnet MS/TP)
Greystone HN series humidity and temperature transmitters with BACnet MS/TP and an optional relay.
Also known as: HN, HNXXXBAC, Greystone HN humidity sensor - Humidity / temperature sensor with condensation monitoring
Greystone Energy Systems HTX1 Series rough duty RH / temperature transmitter (BACnet MS/TP)
Greystone HTX1 series rough-duty RH/temperature transmitters (PICS model DP0011) with optional pipe-temperature condensation probe, digital input and relay, using BACnet MS/TP.
Also known as: HTX1, HTX1XXXBAC, DP0011, NPI-56, Greystone rough duty sensor - Indoor air quality multi-sensor (CO2 / PM / VOC / formaldehyde)
Greystone Energy Systems IAQRM Series multi-sensor (BACnet MS/TP)
Greystone IAQRM series room multi-sensors (PICS model MSN) measuring temperature, RH, CO2, VOC, particulates and formaldehyde, with BACnet MS/TP.
Also known as: IAQRM, MSN, IAQRMXXXBAC, Greystone indoor air quality multi sensor - Room temperature / humidity sensor
Greystone Energy Systems NTRC Series temperature / humidity room sensor (BACnet MS/TP)
Greystone NTRC series network room sensors (temperature, optional RH, setpoint, fan switch, override, relay and digital input) with BACnet MS/TP.
Also known as: NTRC, NTRCXXXBAC, STAT, Greystone NTRC network room sensor - Particulate matter (PM2.5 / PM10) sensor
Greystone Energy Systems PM Series particulate matter transmitter (BACnet MS/TP)
Greystone PM series particulate transmitters for room, duct and outdoor mounting (PMRMC, PMDT, PMOS) with BACnet MS/TP.
Also known as: PM Series, PMRMC, PMDT, PMOS, PMXXXBAC, Greystone particulate sensor - Room differential pressure sensor / monitor
Greystone Energy Systems RPC Series room pressure sensor (BACnet MS/TP)
Greystone RPC series room pressure monitors with local alarm buzzer and BACnet MS/TP.
Also known as: RPC, RPCXXXBAC, Greystone room pressure monitor - Ultra-low differential pressure sensor / transducer
Greystone Energy Systems UP Series ultra-low pressure transducer (BACnet MS/TP)
Greystone UP series ultra-low differential pressure transducers with BACnet MS/TP.
Also known as: UP, UPB, UPXXXBAC, Greystone ultra low differential pressure - VOC air quality sensor
Greystone Energy Systems VOC Series air quality transmitter (BACnet MS/TP)
Greystone VOC series room air quality transmitters (VOC with RH and temperature) with BACnet MS/TP and optional relay.
Also known as: VOC Series, VOCXXXBAC, Greystone VOC sensor, Greystone TVOC transmitter
Source: CDD3 Series Carbon Dioxide Transmitter - Setup Guide BACnet Communication · SG-CDD3A1XXXBAC-003 · rev. 2022-04-21 (PICS date). Object names, instances and units are reproduced as published; descriptions are our own.