2. Product Overview
2.1 Introduction to HMDW110 Series
HMDW110 series transmitters are accurate humidity and temperature transmitters for
measurements in HVAC and cleanroom applications. The series consists of the following
models:
• HMD110/112 models for installation in ventilation ducts
• HMW110/112 models for wall installation
• HMS110/112 models for outdoor use
HMDW110 transmitters can be ordered as:
• Loop powered models, with 2-wire current outputs for humidity and temperature
• Separately powered models, with RS-485 Modbus RTU output
HMD112, HMW112, and HMS112 are standard models that are preconfigured for current output at
the factory. HMD110, HMW110, and HMS110 are factory configurable models that are delivered
with customer specific output settings, including calculated humidity parameters and special
scaling of current outputs or factory activated Modbus RTU functionality.
When used as loop powered current output transmitters, HMDW110 series transmitters can be
connected to Vaisala Remote Display Panel RDP100 for real-time viewing of the
measurements. HMDW110 series can also supply the operating power to the display using only
the loop power from the outputs.
2.2
Output Parameters Explained
HMDW110 series transmitters oer several output parameters. Relative humidity (RH) and
temperature (T) are the measured parameters, the others are calculated based on RH and T.
Table 3 HMDW110 Series Output Parameters
Parameter Symbol Units Description
Temperature T °C
°F
Temperature in Celsius or Fahrenheit scale.
Relative humidity RH % Ratio of the partial pressure of water vapor in the air to the
saturation vapor pressure of air at current temperature.
Dew point T
d/f
°C
°F
Temperature at which the water vapor in the air will
condense into water at the current pressure. When the dew
point is below 0 °C, the transmitter outputs frost point (T
f
)
instead of dew point.
Chapter 2 – Product Overview
9
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