Vaisala HMW90 Series Humidity & Temperature Transmitter


  • Both analog and digital output.
  • Easy installation, configuration, and field adjustment.
  • Humidity parameter options: relative humidity, dew point, mixing ratio, enthalpy, wet bulb temperature, dew point depression, and absolute humidity.
  • Full 0 … 100 %RH measurement range.
  • Up to ±1.7 %RH accuracy.
  • User exchangeable humidity and temperature module.
  • Traceable calibration (certificate included).
  • Available in two colors.

Dpstar is a leader in environmental and industrial measurements. Curiosity and innovation are core values in our company. Our extensive knowledge and expertise are materialized in our selection of innovative products. Accurate measurements are essential for healthy indoor air and improving the energy efficiency of buildings. The unique, cutting-edge Dpstar sensor technologies are manifested throughout our versatile range of products. The transmitters have an exceptionally long lifetime and excellent measurement stability, thus being practically maintenance-free. These are among the many reasons why Dpstar’s products are a sustainable choice.

Wall-mounted Vaisala HMW90 Series HUMICAP Humidity and Temperature Transmitters measure relative humidity and temperature in indoor HVAC applications, where high accuracy, stability, and reliable operation are required. The flexible HMW90 series offers a variety of options and features. Transmitters include a display and a sliding cover with either an opening for the display or a solid front. Both analog and digital output options, including special scalings and calculated parameters are available.


Dimensions of HMW90 series transmitter cover (left) and mounting base (right).

Quick & Easy To Install

HMW90 series transmitters are quick and easy to install. The wiring is connected through the backplate and the electronics with the sensors can be snapped on easily after the wiring is complete. The transmitter is configured using DIP switches, which are accessible when the enclosure is open.

Digital Communication

The introduction of digital (BACnet/Modbus) communication to field-level devices brings many advantages. For example, all sensors can be centrally accessed and their performance can be easily monitored. Wiring is simple when multiple sensors are installed on the same bus. Sensors can be set up using standardized tools, and the system can be expanded with additional sensors quickly and conveniently. In addition, parameters influencing measurements, such as pressure or site elevation, can be centrally set and updated.

Wide Variety Of Calibration Options

On-site calibration and adjustment is exceptionally easy. The sliding cover exposes offset trimmers for one-point calibration without disturbing the measurement. The display instantly indicates the effects of changes, making it clear and convenient to make adjustments. A service port enables two-point calibration, using either a PC or Vaisala HUMICAPâ Handheld Humidity and Temperature Meter HM70. HMW90 series transmitters include a user exchangeable measurement module, which can be ordered as a spare part.

Models Available

  • TMW92 T transmitter, current output
  • TMW93 T transmitter, voltage output
  • HMW92(D) RH+T transmitter, current output (with display)
  • HMW93(D) RH+T transmitter, voltage output (with display)
  • HMW95(D) RH+T digital (BACnet, Modbus) transmitter (with display)
  • TMW90 T transmitter, configurable analog output model
  • HMW90 RH+T transmitter, configurable analog/digital model

The HMW90 and TMW90 transmitters are available in two color options: standard white and black.


Typical applications include museums and archives, production and warehouse facilities, data centers, laboratories, and testing environments. 5-year warranty is valid for instruments purchased in 2021 and beyond. The HMW90 series measures relative humidity and temperature in indoor environments, where high accuracy, stability, and reliable operation are required. The HMW90 is a flexible product family with a variety of options and features, both analog and digital output models are available. The sensors are exceptionally easy to configuration, install, and adjust in the field. Calculated humidity parameters (Td, x, h, Tw, a, T-Td).



Transmitter Models

Model Measurements Output
TMW92 T-only 2-wire, current output
TMW93 T-only 3-wire, voltage output
TMW90 T-only Configurable analog output model
HMW92 RH+T 2-wire, current output
HMW92D RH+T 2-wire, current output with display
HMW93 RH+T 3-wire, voltage output
HMW93D RH+T 3-wire, voltage output with display
HMW90 RH+T Configurable analog/digital model
HMW95 RH+T Digital (BACnet, Modbus) model
HMW95D RH+T Digital (BACnet, Modbus) model with display


Technical Data

Relative humidity
Measurement range 0 … 100 %RH, non-condensing
Accuracy at temperature range +10 … +40 °C (+50 … +104 °F): 0 … 90 %RH
90 … 100 %RH
±1.7 %RH
±2.5 %RH
Accuracy at temperature range −5 … +10 °C, +40 … + 55 °C (+23 … +50 °F, +104 … +131 °F): 0 … 90 %RH
90 … 100 %RH
±3 %RH
±4 %RH
Stability in typical HVAC applications ±0.5 %RH/year
Humidity sensor HUMICAP 180R
Measurement range −5 … +55 °C (+23 … +131 ºF)
Accuracy at +20 … +30 °C (+68 … +86 °F) ±0.2 °C (± 0.36 °F)
Accuracy at +10 … +20 °C, +30 … +40 °C (+50 … +68 °F, +86 … +104 °F) ±0.3 °C (± 0.54 °F)
Accuracy at −5 … +10 °C, +40 … +55 °C (+23 … +50 °F, +104 … +131 °F) ±0.5 °C (± 0.90 °F)
Temperature sensor Digital temperature sensor
Inputs & Outputs
Service port RS-485 line for temporary service use
Current Output Models
Outputs 2 × 4 … 20 mA, loop-powered
Loop resistance 0 … 600 Ω
Supply voltage 20 … 28 VDC at 500 Ω load
10 … 28 VDC at 0 Ω load
Isolation between output channels 500 VDC
Voltage Output Models
Outputs 2 × 0 … 5 V or 2 × 0 … 10 V
Load resistance 10 kΩ min
Supply voltage 18 … 35 VDC, 24 VAC ±20 % 50/60 Hz
Max. current consumption 12 mA
Max. with relay 25 mA
Relay 1 pc (max 50 VDC/50 VAC, 500 mA)
Digital Models
Supply voltage 18 … 35 VDC, 24 VAC ± 20 % 50/60 Hz
Max. current consumption (with 120 Ω termination) 30 mA at 24 VDC
Output type RS-485 (galvanic isolation, 1.5 kV)
RS-485 end of line termination Enable with jumper, 120 Ω
Supported protocols BACnet MS/TP or Modbus RTU (selectable by DIP switch)
BACnet MS/TP Operating mode Slave
Address range, slave mode 128 … 255
Modbus RTU address range 1 … 247
Operating environment
Operating temperature −5 … +55 °C (+23 … +131 °F)
Storage temperature −30 … +60 °C (−22 … +140 °F)
EMC compatibility IEC/EN/BS 61326‑1, industrial environment
Compliance marks CE, RCM, WEEE
IP rating IP30
Weight 155 g (5.5 oz)
Standard housing color White (RAL9003 1))
Optional housing color (configurable
models only)
Black (RAL9005 1))
Housing material ABS/PC, UL-V0 approved
Output connector Screw terminals
Max. wire size 2 mm2
Service port connector 4-pin M8
1) RAL code is only indicative with potential small variations in color shade.
Spare parts and accessories
Humidity and temperature module HTM10SP
Temperature module (for T-only models) TM10SP
Decorative cover set (10 pcs) 236285
Connection cable for HM70 handheld meter 219980
USB cable for PC connection 219690


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