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CO2 sensor | wall mounting | LED indicators | 24 V DC

Article code RSMFF-3
GTIN 0.540.100.301.884.2
Intrastat number
Category Room CO2 sensors
Current stock 8 U.

Product description

Temperature, relative humidity, CO2, and ambient light level sensors for HVAC systems. This carbon dioxide sensor is typically used to monitor the levels of carbon dioxide in schools, offices, restaurants, etc.

The CO2 level is visually indicated by the green, yellow, and red LED indicators. The LEDs used for status indication have adjustable light levels.

Through Modbus RTU communication and three analogue outputs, the measured values are transmitted. The output type by default is 0-10 Volt. Different output types are available. The ventilation system can be controlled based on the occupancy of the room using ambient light detection.

24 V DC is the supply voltage. Modbus RTU communication allows for the adjustment of all parameter settings.

Additional specifications and description

Photo-acoustic NDIR sensing technology
People produce CO2 or carbon dioxide while breathing. That makes CO2 concentration a good indicator for the occupancy and activity level in a space. In many applications, CO2 sensors are used as an indicator for the ventilation requirements. This HVAC transmitter offers a clear, visual indication of the CO2 level via the green, yellow and red LED. The green LED indicates that the CO2 level is within range - there is sufficient fresh air supply. When the CO2 level enters the alert range, the yellow LED lights up. Red means that CO2 levels are too high or that there is insufficient fresh air supply. The measured temperature, relative humidity, CO2 and ambient light level are available via Modbus RTU. Photo-acoustic sensing technology is used to measure the CO2 level. This makes the sensor very sensitive and specific, making it useful for the detection of various gases. The use of specific infrared wavelengths that correspond to CO2 absorption lines ensures that interference from other gases is minimised.
In contrast to transmissive NDIR sensors, photoacoustic NDIR sensors measure the energy absorbed by CO2 molecules. When the infra-red emitter is pulsed, CO2 molecules absorb infrared light on a regular basis. This causes additional molecular vibration, which results in a pressure wave within the measurement chamber. The higher the concentration of CO2, the more light is absorbed, and thus the amplitude of the acoustic wave increases. A microphone inside the gas chamber detects this, and the CO2 concentration can then be calculated. Photoacoustic NDIR sensing allows for much more miniaturisation of the measurement chamber. Furthermore, because sound waves are omnidirectional, the relative position of the emitter and microphone is unconstrained. Thus, photoacoustic NDIR sensors are typically more mechanically and thermally robust. 
Three analogue outputs to transmit the measured values
This sensor has three analogue 0-10 Volt outputs. Each of them transmits one of the measured values. E.g. by default, output 1 will transmit 0 Volt at 0 °C and 10 Volt at 50 °C. Each output value varies proportionally in function of the measured temperature, humidity or CO2 concentration. The measured temperature is available via output 1, relative humidity via output 2 and CO2 concentration via output 3. By default the output type is 0-10 Volt. Other output types can be selected via de Modbus holding registers.
Visual indication of the measured value Wall mounting CO2 sensor
This HVAC transmitter offers a clear, visual indication of the CO2 level via the green, yellow and red LED. The green LED indicates that the CO2 level is within range - there is sufficient fresh air supply. When the CO2 level enters the alert range, the yellow LED lights up. Red means: CO2 out of range or insufficient fresh air supply. The ranges can be adjusted via the Modbus holding registers. The LED indicators can visualize the status of one of the three measured values, by default CO2.
4-wire connection
The cage clamp terminal blocks reduce wiring and installation time. They eliminate the need for routine maintenance and guarantee a reliable contact for solid or stranded wires. The supply voltage is 24 VDC. The ground terminals of the power supply (V-) and output (GND) are internally not connected. This means that a 4-wire cable is required to connect this sensor. Two wires for the supply voltage and (minimum) two wires to connect the output(s). Most 24 VDC power supplies offer protection against short circuit, overload and overvoltage. A 24 VDC supply voltage increases the safety and reliability of your installation.
Self-calibrating to compensate sensor drift
The ABC logic self-calibrating algorithm is enabled by default. This algorithm is intended for use in applications where CO2 concentrations will fall to outside ambient conditions (400 ppm) at least once (15 minutes) in a 7-day period, as is common during unoccupied periods. The sensor will reach operational accuracy after 25 hours of continuous operation when exposed to 400 ppm 10 ppm CO2
Surface mounting sensor installed on wall socket
This sensor can be installed indoors on a wall or on a surface. The mounting holes are adapted to standard European wall mounting boxes. The sensor can be attached to the wall mounting box with two screws. The sensor enclosure will cover the entire wall mounting box. To ensure optimal performance, the sensor should be protected from direct sunlight.
Enclosure with contemporary design
The enclosure is designed for indoor use. It offers an IP30 protection against ingress of dust and moisture. The enclosure is exceptionally strong thanks to the use of high quality r-ABS plastic. Thanks to its contemporary modern design, this sensor can be used in most interior styles.

Remarks, reviews & ratings

Multifunctional room sensor, very easy to use, has free selectable temperature, relative humidity and CO2 ranges. A nice innovative product accessible via Modbus RTU.
No need to calibrate the CO2 sensor element as it has a self-calibration algorithm.
Easy to use and set CO2 sensor. It also measures temperature and humidity in combination with 3 analog outputs is a good solution for your HVAC installation.
CO2 sensor with nice design. Easy to commision.
Easy to connect and looks nice.
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