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CO / NO2 gas sensor · BACnet points list
Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP BACnet points list
Updated 12 November 2026Unofficial source
The GSTC is an electrochemical CO or NO2 transmitter for parking garages and similar spaces. A DIP switch picks BACnet MS/TP or Modbus RTU. Over BACnet it has one Analog Input for the gas level in ppm, a Binary Value to zero the sensor and two Date Values the user fills in for the calibration and sensor replacement dates.
This page lists 4 BACnet objects for the Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP — 3 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from a copy of Dwyer’s documentation hosted by Instrumart, not by Dwyer itself, so treat it as unofficial.
- Manufacturer
- Dwyer
- Model
- Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP
- Equipment
- CO / NO2 gas sensor
- Equipment type
- Thermostats, sensors & meters
- BACnet objects
- 4 (3 writable)
- Transport
- BACnet MS/TP
- Firmware
- Not stated
- Default device instance
- 607000 + DIP switch address (607xxx)
- Also known as
- GSTC, GSTC-C, GSTC-N, Series GSTC, DwyerOmega GSTC, CO Detector, NO2 Detector
- Source document
- Series GSTC Carbon Monoxide / Nitrogen Dioxide Gas Transmitter - Specifications, Installation and Operating Instructions · Bulletin AQ-GSTC (FR# 443872-00 Rev. 6) · rev. 2/19 (unofficial copy, hosted by Instrumart)
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 GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP
Set the address and BACnet protocol on the DIP switches and read AI 1 for the gas level in ppm. Alarm and fan logic live in the BMS.
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 | CO Concentration | Gas level, ppm (CO or NO2 by model) | Read |
Network setup
- Address and protocol (BACnet or Modbus) are set on the DIP switches; valid BACnet addresses are 1-127.
- Device instance defaults to 607xxx, where xxx is the DIP switch address.
- Auto-baud detects the bus speed after power-up.
- DeviceCommunicationControl and ReinitializeDevice need the password "Dwyer".
Watch out for
- Electrochemical sensors drift; Dwyer recommends recalibration every 6 months (5% accuracy holds at 12-month intervals).
Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas 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 | CO Concentration | CO (GSTC-C) or NO2 (GSTC-N) gas level | ppm | Read | |
| BV | 1 | Zero Sensor | Write active to re-zero the sensor | Write | 0=Inactive, 1=Active | |
| Other | 1 | Calibration Date | Date Value: last calibration date, entered manually | Write | ||
| Other | 2 | Replace Sensor Date | Date Value: suggested sensor replacement date, entered manually | Write |
No points match these filters.
Object ID lookup: Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP point IDs by name
Integration notes
- AI 1 is named "CO Concentration" on CO models and "NO2 Concentration" on NO2 models.
- Calibration Date and Replace Sensor Date are BACnet Date Value objects (DV 1, DV 2), listed here as Other.
- The Date Values are not tracked by the transmitter; someone has to write them after field calibration or sensor replacement.
- The BV 1 property table shows Present_Value as Read, but the text says writing it active zeroes the sensor; marked writable here.
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 GSTC carbon monoxide / nitrogen dioxide gas 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 Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP
How many BACnet points does the Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP have?
This list has 4 BACnet objects: 1 analog input, 1 binary value, 2 others. The exact set on a given unit depends on its firmware, installed options and configuration.
Which Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP BACnet points are writable?
3 of the 4 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 GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP BACnet documentation?
Dwyer does not publish it on its own website. This list comes from Series GSTC Carbon Monoxide / Nitrogen Dioxide Gas Transmitter - Specifications, Installation and Operating Instructions (Bulletin AQ-GSTC (FR# 443872-00 Rev. 6)), revision 2/19, a copy hosted by Instrumart at https://core.instrumart.com/assets/Dwyer-GSTC-Manual.pdf. Ask Dwyer or its representative for the current revision.
What are the minimum BACnet points to integrate the Dwyer Series GSTC carbon monoxide / nitrogen dioxide gas transmitter, BACnet MS/TP?
Start with AI 1 CO Concentration (Gas level, ppm (CO or NO2 by model)).
How do I check these points on the real Series GSTC carbon monoxide / nitrogen dioxide gas 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 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 - CO2, humidity and temperature room sensor
Dwyer Series CDTA / CDTC Communicating CO2 Detector
Dwyer Series CDTA (CO2, humidity, temperature) and CDTC (CO2, temperature) wall-mount detectors with setpoint and override, BACnet MS/TP or Modbus RTU.
Also known as: CDTA, CDTC, CDTA-2N000, CDTA-5N000, CDTC-2N000, CDTC-5N000, CDTA-2N000-LCD - 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 - 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 GSTC Carbon Monoxide / Nitrogen Dioxide Gas Transmitter - Specifications, Installation and Operating Instructions · Bulletin AQ-GSTC (FR# 443872-00 Rev. 6) · rev. 2/19. Object names, instances and units are reproduced as published; descriptions are our own.