Humidity transmitters for building automation systems that use Modbus serial communication protocol

RHT-MOD relative humidity transmitters are engineered for building automation systems in the HVAC/R industry. The RHT measures relative humidity (rH), and temperature (T). RHT devices are available with large touchscreen display making configuration of the device quick and easy. Configuration is also possible via Modbus network.


RHT-MOD devices include:

• Separate field configurable Modbus output for each measurement parameter (rH, T)

• Offset feature enabling field calibration for each measurement parameter (rH, T)

• One analog output for selected measurement: voltage (0/2–10 V) and current (4–20 mA)

• Optional relay output

Technical details

Communication: RS-485 Modbus (RTU)
Accurary: Temperature: <0.5 °C
Relative humidity: ±2…3 % rH at 0…50 °C and 10…90 % rH
Total error band includes accuracy, hysteresis and temperature effect over 5...50 °C and 10–90 % rH
Measuring units: °C, % rH
Measurement elements: Integrated temperature sensor, thermoset polymer capacitive sensing element for humidity
Supply voltage: 24 VDC/VAC ±10 %
Current consumption: max 90 mA (at 24 V) + 10 mA for each voltage output or 20 mA for each current output
Output signal for selected measurement: 0/2…10 V (linear to rH or T) (2–10 VDC display models only) or 4…20 mA (linear to rH or T)
Optional relay output: Potential free SPDT 250 VAC, 6 A / 30 VDC, 6 A with adjustable switching point and hysteresis
Operating temperature: 0...50 °C
Protection standard: IP20




Product series

Relative humidity transmitter, analog outputs
Relative humidity transmitter, Modbus communication


Wall mount


With relay
Without relay


With display
Without display