Description:

This card uses the DS2438 1-wire IC to measure temperature, the +5V power supply and the reading from a Honeywell HIH-3610 RH sensor. From these 3 readings the temperature, relative humidity in %, dew point temperature and vapor pressure deficit can all be calculated. The probe is mounted inside a radiation shield that can be hung from the ceiling or a cross arm. The probe can be used to measure indoor or outdoor temperature and humidity for applications such as greenhouse environmental control.

Card Type: 3

OWconfig:

The "Type" must be 3 as described above. The "Mode" must be "Separate power".

Modbus Register Information:

This device has four Modbus input registers on the ICONIO board, temperature, power supply value, RH raw reading and an unused register.

Modbus Register	Modbus Range	Conversions	Description
R1	0-5760	F=0.05625*raw-67 C=0.03125*raw-55	Temperature
R2	0 to 1023	V1=R2/100	Power Supply Value
R3	0 to 1023	V2=R3/100	RH Raw Reading
R4	---	Unused	Unused
		RH=161.29*((V2/V1-.16)/ (1.0546-(.00216*C)))	RH %
		Dew Point C= C 'dp' RH Dew Point F=1.8*(Dew Point C)+32	Dew Point
		VPD=C 'vpd' RH	Vapor Pressure Deficit

Specifications:

Parameter	Specification
Temperature Range	-40 to +85 C (-40 to +185F)
Temperature Accuracy	+/- 2.0C
Temperature Resolution	0.03125C
RH Range (Operating)	0-100% Non-condensing. Extended exposure to >90% RH causes a reversible shift of 3%.
RH Range (Storage))	0-90% Non-condensing
RH Accuracy	±2% RH, 0-100% RH non-condensing, 25 °C, Vsupply = 5 Vdc
RH Interchangeability	±5% RH, 0-60% RH; ±8% @ 90% RH typical
RH Linearity	±0.5% RH typical
RH Hysteresis	±1.2% RH span maximum
RH Repeatability	±0.5% RH
RH Response Time	1/e 15 sec in slowly moving air at 25 °C
RH Stability	±1% RH typical at 50% RH in 5 years
RH Light Sensitivity	This sensor is light sensitive. For best results, shield the sensor from bright light.