Model HC2S3 Temperature and Relative Humidity Probe
5. Overview
The HC2S3 is a digital probe with 0 to 1 V linear output signals for
temperature and humidity, and a UART serial interface. The voltage signals
can be measured with two single-ended or two differential inputs on the
datalogger. A special Rotronic cable and the SDM-SIO1 Serial I/O Module or
MD485 RS-485 Interface is required to interface with the UART as described
in Appendix B.
The D/A converter used to generate the analog output signals has 16-bit
resolution. The default configuration is for temperature -40° to +60°C, and
0 - 100% relative humidity. Temperature range and other default settings can
be changed as described in Appendix A.
A cable ordered through Campbell Scientific for the HC2S3 includes an
internal voltage regulator that applies 3.3 V to the probe from a 5 to 24 V
power source. 12V power is recommended for use with Campbell Scientific
dataloggers. Where minimizing power use is important, power can be
switched on and off for the measurement provided there is a three-second
warm-up delay. Switching power avoids the constant current flow through
datalogger ground, which can affect the accuracy of low level single-ended
voltage measurements, primarily with older dataloggers such as the 21X.
Probes are polarity protected by the keyed connector and a diode in the
connector interface provided with the Campbell Scientific cable.
Campbell Scientific offers two filters:
Polyethylene filter: Default filter, protection against fine dust
particles, no water absorption or retention, good response time.
Teflon filter: Recommended for marine environments, slower
response time than the polyethylene filter, ordered separately.
Campbell Scientific offers the HC2S3-L and HC2S3-QD. The HC2S3-L has a
user-supplied cable length and several cable termination options. When the
HC2S3-L is ordered, enter the cable length, in feet, after the –L; for example,
HC2S3-L11 for a probe with an 11 foot cable. TABLE 5-1 gives the
recommended lengths for various mounts.
TABLE 5-1. Recommended Lead Lengths
2 m Height
Atop a tripod or tower via a 2 ft crossarm such as the CM202
Mast/Leg CM202 CM6
CM10
CM110
CM115
CM120
UT10
UT20
UT30
9' 11'
11'
14'
14'
19'
24'
14'
24'
37'
Note:
Add two feet to the cable length if you are mounting the enclosure on the leg base of a CM106 or CM110
series tripod.
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