Product manual

Model HC2S3 Temperature and Relative Humidity Probe
8
5. Example Programs
This section is for users who write their own datalogger programs. A
datalogger program to measure this sensor and wiring diagram can be created
using Campbell Scientific’s Short Cut Program Programming Wizard. Short
Cut supports most CSI dataloggers (CR7, 21X, CR10, CR500, CR510,
CR23X, CR3000, CR5000). You do not need to read this section to use Short
Cut.
The temperature and relative humidity signals from the HC2S3 can be
measured using a single-ended analog measurement or a differential analog
measurement. Differential measurements are recommended for cables longer
than 6.0 m (20') as discussed in Section 6.
The HC2S3 output scale is 0 to 1000 mV for the temperature range of
-40°C to +60°C and 0 to 1000 mV for the relative humidity range of 0 to
100%. Multipliers and Offsets for the measurement instructions to convert the
measurement result (mV) to temperature and relative humidity are shown in
Tables 5-1 and 5-2.
TABLE 5-1. Temperature
Units
Multiplier
(degrees mV
-1
)
Offset
(degrees)
Celsius 0.1 -40
Fahrenheit 0.18 -40
TABLE 5-2. Humidity
Units
Multiplier
(% mV
-1
)
Offset
(%)
Percent 0.1 0
Fraction 0.001 0
5.1 Example Programs using Single-Ended Measurement
Instructions
The example programs for the CR1000 and CR10X use the SW12V terminal
to switch power to the probe, delay for 3 seconds and measure the output
voltages using single-ended measurement instructions.
Relative humidity and temperature (deg C) are measured on single-ended input
channels 1 and 2 respectively. The program sets relative humidity = 100 if the
measured value is > 100 but less than 103%. Values > 103% are not set = 100,
and indicate a problem with the sensor or its calibration.