HK Instruments Siro-MOD-CO2-rH-T-A-D Indoor Air Quality Transmitter (CO2; rH; T)

Measurement ranges:

+ CO2:  0–2000 ppm / 400–2000 ppm  (selectable via jumper)

+ Temperature: 0...50 °C

+ Relative humidity:  0–100 %rH

Communication: RS-485 Modbus (RTU)

Accuracy: 

+ CO₂: ±40 ppm + 3 % of reading (typical), additional ±60 ppm for first weeks 

+ Relative humidity: ±2.2 % rH (typical at 20 °C, 30 % rH) 

+ Temperature: ±0.4 °C (typical at 20 °C)  

Measuring elements: 

+ CO2: Non-dispersive infrared (NDIR) 

+ Temperature: Integrated to CMOS 

+ Relative humidity: Thermoset polymer capacitive sensing element 

Measuring units: 

+ CO2: ppm 

+ Relative humidity: % rH 

+ Temperature: °C 

Calibration (CO2): Automatic self-calibration, ABC LogicTM

Supply voltage: 24 VDC/VAC ±10 %

Output signal 1–4: 0...10 V (optional 2...10 V / 0...5 V, display or configuration tool required); Optional 4...20 mA

Linear to selected measurement (CO2, VOC, PM, rH or Temp) 

Operating temperature: 0...50 °C

Protection standard: IP20

Noted:

CO2 = Carbon dioxide sensor

rH = Humidity sensor

T = Temperature sensor

A = mA output

D = Display