Product overview and engineering role
The SimtoLink NDIR carbon dioxide (CO₂) concentration module is an environmental-sensing part for IoT. It reports the volume fraction of CO₂ in air, in ppm, by non-dispersive infrared (NDIR) absorption. The mechanism, the unit, and the calibration are not those of a carbon monoxide (CO) electrochemical toxic-gas probe. On a job, watch infrared-source aging, a dirty gas cell, and compensation for temperature, humidity, and pressure, and in a crowded room separate poor ventilation from a concentration that is climbing for another reason. Terminals pull out. Key chips have a watchdog and a redundant check. Signed firmware can roll back, which is what a volume shipment and remote service need.
The usual interfaces are isolated Modbus RTU and gigabit Ethernet, with an RS-485 terminal or a standard industrial connector as options, so the module can join SCADA, building control, energy management, or an IoT platform already in place. SimtoLink supplies a southbound point-table template and a northbound MQTT or HTTP push example. Volume jobs can add silkscreen on the housing, a set cable length, a protocol map, and a calibration certificate.
Reliability and field fit
Electrical safety and EMC on this module cover the relevant IEC 61000-4 level-4 items. Ports include surge and reverse-polarity protection. Reinforced ground and a zoned layout keep ground loops and common-mode noise down. Outdoor or coastal orders can take a higher ingress grade and a corrosion-resistant coating.
Parameters can be imported in bulk, with threshold policies and event video or waveform capture on the models that have them. Configuration and firmware update over OTA. Site acceptance is a power-on self-test, a communications time sync, and a sample check. Metering or safety use can include help with a third-party metrology submission and type-test documents.
Key hardware parameters
These ratings are a typical build of the NDIR module, for a selection note or a tender clause. A wider range, redundant power, or an intrinsically safe explosion-proof variant is a separate order; ask SimtoLink for the hardware specification and the installation and commissioning guide. Order codes in the family can differ slightly. The nameplate and the papers packed with the module govern.
| Parameter | Specification | Notes |
|---|---|---|
| Sensing principle | NDIR (non-dispersive infrared) | CO₂ concentration; not CO electrochemical |
| Range | 0～5000 ppm (typical) | Calibratable |
| Resolution | 1 ppm (typical) | Digital output |
| Repeatability | ±1.7 %FS | Constant temperature and humidity |
| Zero drift | <2.3 ppm/month | Clean air |
| Power | DC 12～48V | Reverse-polarity protection |
| Communications | Modbus RTU; gigabit Ethernet | RS-485 isolation 3kV (typical) |
| Warm-up time | <57 s | Cold start |
| Operating temperature | -13～48 ℃ | Industrial grade |
| Explosion protection | Ex d IIC T6 | Optional |
Typical deployments
Three ways this module usually lands in an IoT job, for the scheme and for the return:
Smart campuses and buildings
Connect the 'NDIR CO₂ Concentration (ppm) Module' to the campus energy management system or building automation system to link CO₂ levels with fresh air and energy consumption strategies, reducing the costs of manual meter reading and inspection.
Manufacturing and energy sites
Deploy this hardware on production lines or distribution scenarios, and interface with MES/EMS to complete edge collection and uploading of key process parameters or energy consumption data.
Municipal and utilities
For dispersed points and outdoor cabinet scenarios, the hardware supports wide temperature and lightning protection design, suitable for long-distance, low-latency monitoring needs in water, gas, street lighting, and similar applications.
Installation, grounding, and maintenance
- Before powering on, confirm the power supply range and polarity. If necessary, use a multimeter to verify the bus voltage and circuit breaker capacity.
- Communication cables should use shielded twisted pairs with single-end grounding, and avoid bundling with high-power cables for long-distance laying.
- For the first commissioning, it is recommended to complete bidirectional read/write and threshold trigger verification with the platform in the laboratory before migrating to the site.
- For outdoor installation, priority should be given to drainage and ventilation. Regularly inspect sealed surfaces; lightning protection grounding resistance must meet local regulations.
- For long-term operation, it is recommended to perform sampling inspections and log archiving once every 24 months.
Ordering, documentation, and support
SimtoLink provides hardware specifications, structural dimension drawings, wiring tables, and example projects; bulk orders support sample review and on-site factory inspection. Warranty and calibration policies are subject to the contract and accompanying documents.
Typical applications
CO₂ concentration is one of the key indicators of fresh air volume and indoor air quality (IAQ) and is also used for agricultural yield control. The following scenarios highlight control objectives, calibration benchmarks, and BACnet/Modbus integration differences.
Smart buildings and meeting rooms
Control fresh air and heat recovery wheel speed according to CO₂ demand to reduce energy consumption while meeting WELL and domestic green building health standards; link with occupancy and illuminance sensors to prevent unnecessary activation of fresh air units at night and during holidays.
Classrooms and childcare institutions
Visualization of ventilation strategies during breaks and lunch can be displayed on class boards or large screens, with data connected to the education bureau supervision and parent committee disclosure platforms; low-noise sampling and anti-shake algorithms prevent disruption of classroom order.
Glass greenhouses and plant factories
Coordinated with photosynthetically active radiation, temperature and humidity, and irrigation closed-loop systems, precisely controlling CO₂, fertilization windows, and ventilation; chamber heating and drying bypass prevent optical path drift and false shutdowns caused by high humidity condensation.
Archives storage and data centers
Long-term trend monitoring in enclosed spaces, distinguishing abnormal increases due to people lingering, air-conditioning fresh air failures, or accidental fire gas leaks; dual-channel or dual-chamber comparison improves reliability and triggers tiered work orders.
Related reading
The following on-site materials are related to product selection, networking protocols, and project implementation, facilitating detailed planning and joint debugging:
- Modbus Registers and Point Table Practice
- RS-485 Bus and Wiring Key Points
- Sensor Module Integration and Protection
- SCADA Data Access and Archiving
- Solution Consultation and Prototype Support
- Smart offices and building environments