TSM400-4-CPTH_R1.7 –November 2023 Page 2
1. Short description
TSM400-4-CPTH is a multi-sensor that supports MODBUS RTU protocol over the RS-485 interface. The
sensor measures CO2concentration, temperature, humidity, and barometric pressure. The MODBUS
device integrates an advanced non-dispersive infrared sensing element (NDIR) for CO2measurements.
The measurement principle is based on the absorption of infra-red (IR) light with specific wavelengths
by CO2molecules. The carbon dioxide sensing element is temperature compensated for better
accuracy. Self-calibration is available for carbon dioxide measurements. It is done if the sensor is left
in fresh (around 400 ppm CO2concentration) air.
The basic sensing element for barometric pressure is factory calibrated and it does not require any
lifetime recalibration. A unique capacitive element is used for measuring relative Humidity while the
temperature is measured by a band gap sensor. Both sensors are seamlessly coupled to a 12-bit analog
to digital-converter. This results in superior signal quality.
The TSM400-4-CPTH multi-sensor is housed in a slim plastic enclosure. The bottom part of the
enclosure is suitable for installation on standard flush-mounted/cavity wall boxes ø68mm, with
installation openings on 61 mm.
2. Features
•LED indicator for status of communication;
•Long-term stability based on digital signal processing;
•Self-calibration on fresh air for CO2measurements;
•RS-485 interface carrying up to 32 nodes;
•Changeable bitrate and other communication parameters;
•Firmware update via the interface.
3. Applications
•Environmental quality monitoring and assessment for offices
•CO2pollution monitoring
•Server room and data centers humidity and temperature monitoring
•Smart ventilation systems
•CO2, humidity, and temperature monitoring in building management systems (BMS)
4. Specifications
•Physical characteristics
Dimensions: 81 x 81 x 30mm
Weight: 66g
•Environmental limits
Operating temperature range: -20 to 60°C
Operating relative humidity range: 10 to 90% (non-condensing)
Recommended operating range is 20% to 80% RH (non-condensing) over –10 °C to 60 °C
Prolonged operation beyond these ranges may result in a shift of sensor reading, with slow recovery time
Long term drift typical: ±0.25%RH/year, ±0.05°C/year
Higher drift might occur due to contaminant environments with vaporized solvents, adhesives, packaging materials, etc.
Storage temperature range: -20 to 60°C
Storage relative humidity range: 10 to 90% (non-condensing)
Ingress protection: IP20
