Campbell HC2S3 User manual

HC2S3 Temperature
and Relative Humidity Probe
Revision: 10/12
Copyright © 1990-2012
Campbell Scientific, Inc.

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Table of Contents
PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.
1. Introduction.................................................................1
2. Cautionary Statements...............................................1
3. Initial Inspection .........................................................1
3.1 Ships With............................................................................................2
4. Quickstart ....................................................................2
4.1 Step 1 — Mount the Probe...................................................................2
4.2 Step 2 — Use SCWin Short Cut to Program Datalogger and
Generate Wiring Diagram.................................................................4
5. Overview......................................................................7
6. Specifications .............................................................8
6.1 Temperature Sensor .............................................................................9
6.2 Relative Humidity Sensor ..................................................................10
6.3 Default Settings and Digital Interface ................................................10
7. Installation.................................................................11
7.1 Siting ..................................................................................................11
7.2 Assembly and Mounting ....................................................................11
7.3 Wiring ................................................................................................11
7.4 Programming......................................................................................13
7.4.1 Example Programs using Single-Ended Measurement
Instructions ..............................................................................14
7.4.2 Example Programs using Differential Measurement
Instructions ..............................................................................17
7.5 Measuring Probes with Long Cables..................................................19
8. Sensor Maintenance .................................................20
9. Troubleshooting........................................................21
10. References ................................................................21
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Table of Contents
ii
Appendices
A. Absolute Humidity ..................................................A-1
A.1 Measurement Below 0°C................................................................. A-2
B. Changing the HC2S3 Settings ...............................B-1
B.1 HC2S3 Default Settings .................................................................. B-1
B.2 Software and Hardware Requirements ............................................ B-2
B.3 Changing the Temperature Range ................................................... B-2
B.4 Multiplier and Offsets for Temperature Range................................ B-3
C. HC2S3 Digital Communications ............................C-1
C.1 HC2S3 Digital Interface Specifications........................................... C-1
C.2 HC2S3 Communications Protocol................................................... C-1
C.3 RS-485 Communications using an MD485 RS-485 Interface......... C-3
C.4 RS-485 Communications using an SDM-SIO1 Serial I/O Module . C-5
Figures
4-1. HC2S3 and 41003-5 Radiation Shield on a tripod mast ...................... 3
4-2. HC2S3 and 41003-5 Radiation Shield on a CM200 Series Crossarm. 3
Tables
5-1. Recommended Lead Lengths .............................................................. 7
7-1. Connections for Single-Ended Measurements................................... 12
7-2. Connections for Differential Measurements...................................... 13
7-3. Temperature....................................................................................... 14
7-4. Humidity............................................................................................ 14
7-5. Wiring for Single-ended Measurement Examples............................. 14
7-6. Wiring for Differential Measurement Examples ............................... 18
A-1. Wiring for Vapor Pressure Examples.............................................. A-1

Model HC2S3 Temperature and Relative
Humidity Probe
1. Introduction
The HC2S3 is a rugged, accurate temperature/RH probe that is ideal for long-
term, unattended applications. The probe uses a Rotronic’s IN1 capacitive
sensor to measure RH and a 100 ohm PRT to measure temperature. For
optimum results, the HC2S3 should be recalibrated annually.
Before using the HC2S3, please study
•Section 2, Cautionary Statements
•Section 3, Initial Inspection
•Section 4, Quickstart
More details are available in the remaining sections.
2. Cautionary Statements
•Care should be taken when opening the shipping package to not damage or
cut the cable jacket. If damage to the cable is suspected, consult with a
Campbell Scientific applications engineer.
•Although the HC2S3 is rugged, it should be handled as a precision
scientific instrument.
•Do not touch the sensor element.
•The black outer jacket of the cable is Santoprene® rubber. This
compound was chosen for its resistance to temperature extremes, moisture,
and UV degradation. However, this jacket will support combustion in air.
It is rated as slow burning when tested according to U.L. 94 H.B. and will
pass FMVSS302. Local fire codes may preclude its use inside buildings.
3. Initial Inspection
•Upon receipt of the HC2S3, inspect the packaging and contents for
damage. File damage claims with the shipping company.
•The model number and cable length are printed on a label at the
connection end of the cable. Check this information against the shipping
documents to ensure the correct product and cable length are received.
•Refer to the Ships With list to ensure that parts are included (see Section
3.1). The HC2S3 probe and its calibration card are shipped in a small box,
with the box and PN 27731 Hex Plug attached to the cable.
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Model HC2S3 Temperature and Relative Humidity Probe
3.1 Ships With
The HC2S3 ships with:
(1) 27731 Gill Radiation Shield Hex Plug
(1) Calibration Card
(1) Resource DVD
4. Quickstart
4.1 Step 1 — Mount the Probe
Review Section 7, Installation for complete instructions. To install the HC2S3,
you will need:
•41003-5 Radiation Shield
•27731 Hex Plug (ships with HC2S3)
1. Insert the 27731 hex plug that ships with the HC2S3 probe into the
underside of the 41003-5 base.
2. Attach the radiation shield to the tripod mast, crossarm, or tower leg using
the supplied U-bolt. See FIGURE 4-1 and FIGURE 4-2 for examples of
shield mounting.
3. Insert the probe into the radiation shield leaving about 2.5 cm (1 in.)
exposed below the hex plug.
4. Tighten the hex plug such that it compresses against the body of the
HC2S3 to hold it inside the radiation shield.
5. Attach the probe to the cable by aligning the keyed connectors, pushing
the connectors together and tightening the knurled ring.
6. Route the cable to the datalogger, and secure the cable to the mounting
structure using cable ties.
2

Model HC2S3 Temperature and Relative Humidity Probe
FIGURE 4-1. HC2S3 and 41003-5 Radiation Shield on a tripod mast
FIGURE 4-2. HC2S3 and 41003-5 Radiation Shield on a CM200 Series
Crossarm
41003-5
PN 27731 Hex Plug
U-bolt
CM200 Series Crossarm
3

Model HC2S3 Temperature and Relative Humidity Probe
4.2 Step 2 — Use SCWin Short Cut to Program Datalogger
and Generate Wiring Diagram
The simplest method for programming the datalogger to measure the HC2S3 is
to use Campbell Scientific's SCWin Short Cut Program Generator.
1. Open Short Cut and click on New Program.
2. Select a datalogger and scan interval.
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Model HC2S3 Temperature and Relative Humidity Probe
3. Select HC2S3 Temperature and Relative Humidity Sensor and choose
either constant power or panel switched power (uses less current), then
click the right arrow to add it to the list of sensors to be measured.
4. Define the name of the public variables. Variables default to AirTC and
RH that hold the air temperature and relative humidity measurements.
Select the desired units of measure. Units default to Deg C.
5

Model HC2S3 Temperature and Relative Humidity Probe
5. Choose the outputs for the AirTC and RH and then select finish.
6. Wire according to the wiring diagram generated by SCWin Short Cut.
6

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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Model HC2S3 Temperature and Relative Humidity Probe
The HC2S3-L's cable can terminate in:
•Pigtails that connect directly to a Campbell Scientific datalogger
(cable termination option –PT; see Section 4).
•Connector that attaches to a prewired enclosure (cable termination
option –PW).
•Connector that attaches to a CWS900 Wireless Sensor Interface (cable
termination option –CWS). The CWS900 enables the probe to be used
in a wireless sensor network.
•Connector that attaches to the Temp/RH connector on a CS110
Electric Field Meter or ET-series weather station (cable termination
option –C).
•Military-style connector that attaches to the Temp/RH connector on a
RAWS-P Permanent Remote Automated Weather Station (cable
termination option –RQ).
The HC2S3-QD is included with the RAWS-F Quick Deployment Remote
Automated Weather Station and can be ordered as a replacement part. Its cable
has a 65-in. length and terminates in a military-style connector that attaches to
the Temp/RH connector on the RAWS-F connector panel.
6. Specifications
Features:
•Well-suited for long-term, unattended applications
•Accurate and rugged
•Compatible with all Campbell Scientific dataloggers (including the
CR200(X) series)
Compatibility: CR200(X) series
CR800 series
CR1000
CR3000
CR5000
CR9000(X)
CR7X
CR510
CR10(X)
CR23X
21X
Operating Limits at Electronics: -40°to +100°C
Storage Temperature: -50°to +100°C
Probe Length: 85 mm (3.3 in.), 183 mm (7.25 in.)
including connector
Probe Diameter: 15 mm (0.6 in.)
Probe Weight: 10 g (0.35 oz)
Filter: Polyethylene or Teflon (optional,
ordered separately)
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Model HC2S3 Temperature and Relative Humidity Probe
Power Consumption: <4.3 mA @ 5 V
<2.0 mA @ 12 V
Supply Voltage (using CSI cable): 5 to 24 Vdc (12 Vdc recommended)
Start-up time: 1.5 s typical (Rotronic specification,
Campbell Scientific recommends 2 s at
60°C, 3 s at 0°C, 4 s at -40°C)
Maximum Startup Current: <50 mA during 2 µs
Maximum Lead Length: 300 m (1000 ft) with 12 V power, 3 m
(10 ft) with 5 V power
Analog outputs
Offset at 0 V: ±3 mV (maximum)
Deviation from Digital Signal: < ±1 mV (0.1°C, 0.1% RH)
6.1 Temperature Sensor
Sensor: PT100 RTD, IEC 751 1/3 Class B, with
calibrated signal conditioning
Temperature Measurement Range: -50°to +100°C (default -40°to + 60°C)
Temperature Output Signal Range: 0 to 1.0 V
Accuracy at 23°C: ±0.1°C with standard configuration
settings
Long Term Stability: <0.1°C/year
Sensor Time Constant (63% step
change (1 m/s air flow at sensor)): ≤22 s with PE filter, ≤30 s with Teflon
filter
Temperature Accuracy over Temperature:
9

Model HC2S3 Temperature and Relative Humidity Probe
6.2 Relative Humidity Sensor
Sensor: ROTRONIC Hygromer®IN1
Relative Humidity
Measurement Range: 0 to 100% non-condensing
RH Output Signal Range: 0 to 1 Vdc
Accuracy at 23°C: ±0.8% RH with standard configuration
settings
Typical Long Term Stability: <1% RH per year
Sensor Time Constant (63% of a
35 to 80% RH step change
(1 m/s air flow at sensor)): ≤22 s with PE filter, ≤30 s with Teflon
filter
RH Accuracy over Temperature:
The black outer jacket of the cable is Santoprene® rubber.
This compound was chosen for its resistance to
temperature extremes, moisture, and UV degradation.
However, this jacket will support combustion in air. It is
rated as slow burning when tested according to U.L. 94
H.B. and will pass FMVSS302. Local fire codes may
preclude its use inside buildings.
CAUTION
6.3 Default Settings and Digital Interface
Please refer to Appendices.
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Model HC2S3 Temperature and Relative Humidity Probe
7. Installation
7.1 Siting
Sensors should be located over an open level area at least 9 m (EPA) in
diameter. The surface should be covered by short grass, or where grass does
not grow, the natural earth surface. Sensors should be located at a distance of
at least four times the height of any nearby obstruction, and at least 30 m
(EPA) from large paved areas. Sensors should be housed in a suitable radiation
shield.
Standard measurement heights:
1.5 m (AASC)
1.25 to 2.0 m (WMO)
2.0 m (EPA)
See Section 10, References for a list of references that discuss temperature and
relative humidity sensors.
7.2 Assembly and Mounting
Tools Required:
•1/2 in. open end wrench
•small screw driver provided with datalogger
•UV resistant cable ties
•small pair of diagonal-cutting pliers
The HC2S3 probe and its calibration card are shipped in a small box, with the
box and PN 27731 Hex Plug attached to the cable. PN 27731 is used to mount
the probe inside the 41003-5 Radiation Shield as described in Section 4,
Quickstart.
Attach the probe to the cable by aligning the keyed connectors, pushing the
connectors together and tightening the knurled ring.
When exposed to solar radiation the probe must be housed in a radiation shield
such as the 41003-5 naturally aspirated shield, or the 43502 motor aspiration
shield (please refer to the 43502 product manual for details). The 41003-5
Radiation Shield has a U-bolt for attaching the shield to a tripod mast/tower leg
or CM200 series crossarm (shown in FIGURE 4-1 and FIGURE 4-2 in the
Quickstart section).
7.3 Wiring
Connections to Campbell Scientific dataloggers for measuring humidity and
temperature using two single-ended or two differential analog inputs are given
in TABLE 7-1 and TABLE 7-2. Use a single-ended analog measurement when
the cable length is less than 6.1 m (20 ft), or if power is switched off between
measurements. For cable lengths longer than 6.1 m or when the probe is
continuously powered, use a differential analog measurement. See Section 7.5
for a discussion on errors caused by long cable lengths.
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Model HC2S3 Temperature and Relative Humidity Probe
The HC2S3 draws approximately 2 mA powered from 12V. The HC2S3 can
be continuously powered from the 12V terminal, or power can be switched
with the SW12V terminal to conserve battery life. When power is switched, a
three-second warm-up time is required. Using the SW12V terminal on the
CR10X datalogger requires a user-supplied jumper wire connected between the
SW 12V CTRL terminal and a Control Port (C1 to C8).
When measuring the HC2S3 with single-ended
measurements, the yellow and gray leads must both be
connected to AG on the CR10(X) and CR500/CR510 or to
on the CR1000, CR5000, and CR23X. Doing otherwise
will connect the datalogger’s analog and power ground
planes to each other, which in some cases can cause
offsets on low-level analog measurements. To avoid 2 mA
flowing into analog ground, switch power on/off for its
measurement.
CAUTION
TABLE 7-1. Connections for Single-Ended Measurements
Color
Description
CR1000,
CR3000,
CR800,
CR5000,
CR23X
CR10X
CR10,
CR510,
CR500
Brown Temperature
Signal
Single-Ended
Input
Single-Ended
Input
White Relative Humidity
Signal
Single-Ended
Input
Single-Ended
Input
Yellow Signal Reference AG
Gray Power Ground AG
Clear Shield G
Green Power 12V/*SW12V 12V/*SW12V
*CR10X Power Control if
using SW 12V
Jumper from
SW 12V
CTRL to
Control Port
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Model HC2S3 Temperature and Relative Humidity Probe
TABLE 7-2. Connections for Differential Measurements
Color
Description
CR1000,
CR3000,
CR800,
CR5000,
CR23X
CR10X
CR10,
CR510,
CR500
Brown Temperature
Signal
Differential
Input – H
Differential
Input – H
Jumper to
Yellow
Temperature Signal
Reference
Differential
Input – L
Differential
Input – L
White Relative Humidity Signal Differential
Input – H
Differential
Input – H
Yellow Signal Reference
Differential
Input – L
Differential
Input – L
Gray Power Ground G G
Clear Shield G
Green Power 12V/*SW12V 12V/*SW12V
*CR10X Power Control if
using SW 12V
Jumper from
SW 12V
CTRL to
Control Port
7.4 Programming
This section is for users who write their own datalogger
programs. You do not need to read this section if using our Short
Cut Program Generator, or connecting the probe to a prewired
enclosure, RAWS-P station, RAWS-F station, or CWS900
Wireless Sensor Interface. Our prewired enclosures, RAWS-P
stations, and RAWS-F stations include a datalogger program.
Refer to the Wireless Sensor Manual for programming
information if using the probe with a CWS900.
NOTE
The temperature and relative humidity signals from the HC2S3 are measured
using either single-ended voltage instructions (VoltSE() in CRBasic or
Instruction 1 in Edlog) or differential voltage instructions (VoltDiff() in
CRBasic or Instruction 2 in Edlog). Differential measurements are
recommended for cables longer than 6.0 m (20 ft) as discussed in Section 7.5.
When the probe is connected to a CS110 Electric Field Meter,
the probe is measured by the CS110's internal CR1000
datalogger module using VoltSE() instructions. Relative
humidity and temperature signals are measured on single-ended
channels 1 and 2, respectively. The 250 µs integration should be
used in the VoltSE() instructions.
NOTE
13

Model HC2S3 Temperature and Relative Humidity Probe
The HC2S3 output scale is 0 to 1000 mV for the temperature range of
-40°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
TABLE 7-3 and TABLE 7-4.
TABLE 7-3. Temperature
Units
Multiplier
(degrees mV-1)
Offset
(degrees)
Celsius 0.1 -40
Fahrenheit 0.18 -40
TABLE 7-4. Humidity
Units
Multiplier
(% mV-1)
Offset
(%)
Percent 0.1 0
Fraction 0.001 0
7.4.1 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 equal to 100
if the measured value is greater than 100 but less than 103%. Values greater
than 103% are not set equal to 100, and indicate a problem with the sensor or
its calibration.
TABLE 7-5. Wiring for Single-ended
Measurement Examples
Color Description CR1000 CR10(X)
Brown Temperature SE 2 SE 2
White Relative Humidity SE 1 SE 1
Yellow Signal Reference AG
Gray Power Ground AG
Clear Shield G
Green Power SW12V SW12V
Jumper from
SW 12V CTRL
to Control Port
14