HC2S3 Temperature and Relative Humidity Probe Revision: 10/12 C o p y r i g h t © 1 9 9 0 - 2 0 1 2 C a m p b e l l S c i e n t i f i c , I n c .
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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.
Table of Contents Appendices A. Absolute Humidity ..................................................A-1 A.1 Measurement Below 0°C................................................................. A-2 B. Changing the HC2S3 Settings ...............................B-1 B.1 B.2 B.3 B.4 HC2S3 Default Settings .................................................................. B-1 Software and Hardware Requirements ............................................ B-2 Changing the Temperature Range ..................
Model HC2S3 Temperature and Relative Humidity Probe 1. Introduction The HC2S3 is a rugged, accurate temperature/RH probe that is ideal for longterm, 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.
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: • • 2 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.
Model HC2S3 Temperature and Relative Humidity Probe 41003-5 PN 27731 Hex Plug U-bolt FIGURE 4-1. HC2S3 and 41003-5 Radiation Shield on a tripod mast CM200 Series Crossarm FIGURE 4-2.
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. 4 1. Open Short Cut and click on New Program. 2. Select a datalogger and scan interval.
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.
Model HC2S3 Temperature and Relative Humidity Probe 6 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.
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.
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.
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.
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: CAUTION 6.
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.
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).
Model HC2S3 Temperature and Relative Humidity Probe TABLE 7-2.
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.
Model HC2S3 Temperature and Relative Humidity Probe CR1000 program using single-ended measurements 'CR1000 program to measure HC2S3 with single-ended inputs Public AirTC Public RH Units AirTC=Deg C Units RH=% DataTable(Table1,True,-1) DataInterval(0,60,Min,10) Average(1,AirTC,FP2,False) Sample(1,RH,FP2) EndTable BeginProg Scan(5,Sec,1,0) PortSet(9,1) 'Turn on switched 12V Delay(0,3,Sec) '3-second delay 'HC2S3 Temperature & Relative Humidity Sensor measurements AirTC and RH: VoltSE(RH,1,mV2500,1,0,0,_60Hz,0.
Model HC2S3 Temperature and Relative Humidity Probe 4: Volt (SE) (P1) 1: 1 2: 25 3: 4 4: 1 5: 0.
Model HC2S3 Temperature and Relative Humidity Probe CR1000 program using single-ended measurements in Slow Sequence scan The following program example has a 1-second main scan, and uses a Slow Sequence scan to measure the HC2S3 every 5 seconds. Every 5 seconds the program switches power to the HC2S3 on the SW-12 terminal, delays for a 3-second “warm-up”, and measures relative humidity and temperature on single-ended channels 1 and 2 respectively.
Model HC2S3 Temperature and Relative Humidity Probe TABLE 7-6.
Model HC2S3 Temperature and Relative Humidity Probe 2: Volt (Diff) (P2) 1: 1 2: 25 3: 2 4: 4 5: 0.
Model HC2S3 Temperature and Relative Humidity Probe The signal reference (yellow) and the power ground (gray) are in common inside the HC2S3. When the HC2S3 temperature and relative humidity are measured using a single-ended analog measurement, both the signal reference and power ground are connected to ground at the datalogger. The signal reference and power ground both serve as the return path for power. There will be a voltage drop along those leads because the wire itself has resistance.
Model HC2S3 Temperature and Relative Humidity Probe 9. Troubleshooting Symptom: -9999, NAN, -40°C, or 0 % relative humidity 1. Check that the sensor is wired to the correct analog input channels as specified by the measurement instructions. 2. Verify the voltage range code for the single-ended or differential measurement instruction is correct for the datalogger type. 3. Verify the green power wire is connected to the 12V, SW12V, or 5V terminal.
Model HC2S3 Temperature and Relative Humidity Probe Lowe, P. R., 1977: An approximating polynomial for the computation of saturation vapor pressure, J. Appl. Meteor., 16, 100-103. Meyer, S. J. and K. G. Hubbard, 1992: Nonfederal Automated Weather Stations and Networks in the United States and Canada: A Preliminary Survey, Bulletin Am. Meteor. Soc., 73, No. 4, 449-457. Weiss, A., 1977: Algorithms for the calculation of moist air properties on a hand calculator, Amer. Soc. Ag. Eng., 20, 1133-1136. WMO, 2008.
Appendix A. Absolute Humidity The HC2S3 measures the relative humidity. Relative humidity is defined by the equation below: RH = e ∗ 100 es (A-1) where RH is the relative humidity, e is the vapor pressure in kPa , and es is the saturation vapor pressure in kPa. The vapor pressure, e, is an absolute measure of the amount of water vapor in the air and is related to the dew point temperature. The saturation vapor pressure is the maximum amount of water vapor that air can hold at a given air temperature.
Appendix A.
Appendix B. Changing the HC2S3 Settings B.1 HC2S3 Default Settings The HC2S3 probe has the following default settings, which can be changed as described in the following sections. Additional information can be found in Rotronic’s User Manual: E-M-HC2 Probes-VXXXX, which can be downloaded from Rotronic's website www.rotronic-usa.com.
Appendix B. Changing the HC2S3 Settings B.2 Software and Hardware Requirements For temperature (Analog Output 2), the HC2S3 default range is -40 to +60°C for 0 to 1V. Changing the range requires Rotronic HW4 Software (Version 2.1.0 or higher), and the Rotronic model AC3001 USB adapter cable. Power to the probe is provided by the USB port. IMPORTANT Prior to using the AC3001 cable, the ROTRONIC USB driver must be installed on the PC.
Appendix B. Changing the HC2S3 Settings Click on “Device Manager”, select “Analog Outputs” to see the following screen: Change the lower and upper range values and click “OK”. The following screen shows the range -60 to +30: B.4 Multiplier and Offsets for Temperature Range Analog Output 2 is 0 to 1V (1000 mV) for the temperature range.
Appendix B. Changing the HC2S3 Settings Example measurement instructions for CR1000 datalogger, with the sensor wired to SE channel 2: Public AirTC VoltSe (AirTC,1,mV2500,2,0,0,_60Hz,0.09,-60) Example measurement instruction for CR10X datalogger: 1: Volt (SE) (P1) 1: 1 2: 5 3: 2 4: 1 5: 0.09 6: -60.
Appendix C. HC2S3 Digital Communications C.1 HC2S3 Digital Interface Specifications The HC2S3 has a UART (Universal Asynchronous Receiver Transmitter) that provides two-way digital communications with the probe. Interface cables can be ordered through Rotronics for connecting the probe to an RS-485 port (Rotronic pn E2-05XX-MOD), a computer's RS-232 port (Rotronic pn AC3002), or USB port (Rotronic pn AC3001).
Appendix C. HC2S3 Digital Communications Command Format: { ID Adr RDD Chksum or } CR Adr RDD Chksum or } CR Answer format: { ID The data are returned according to the following structure: Example Type Description 1..3 Byte Probe type (1= digital probe, 2=analog probe, 3=pressure probe) 1234.56 Float Relative humidity or analog value %RH String Humidity or analog value engineering unit 0..
Appendix C. HC2S3 Digital Communications C.3 RS-485 Communications using an MD485 RS-485 Interface The HC2S3 can be interfaced to a CSI datalogger through an MD485 RS-485 Interface using the Rotronic E2-05XX-MOD RS485 cable as described below. Settings for the RS485 port on the MD485 must be configured to match the configuration of the HC2S3, which are 19200 baud, No Parity, 8 Data Bits, 1 Stop bit, and No Flow Control.
Appendix C. HC2S3 Digital Communications Sensor Wiring: E2-05XX-MOD Cable MD485 Blue A Red B Green Gray/Yellow Clear NOTE CR1000 12V G Ground Symbol If the Rotronic cable includes brown and white wires (voltage signals for temperature and humidity), CSI recommends “capping” them with PN 27749 or equivalent insulated caps to prevent the possibility of shorting. Connect the CS I/O port of MD485 to CS I/O port on CR1000 with an SC12 cable.
Appendix C. HC2S3 Digital Communications C.4 RS-485 Communications using an SDM-SIO1 Serial I/O Module The HC2S3 can be interfaced to a CSI datalogger through an SDM-SIO1 Serial I/O Module using the Rotronic E2-05XX-MOD RS485 cable as described below.
Appendix C. HC2S3 Digital Communications Example CR1000 Program: 'CR1000 Program 'Declare variables Public SerialIndest As String * 100 Dim String_1 As String Const CRLF=CHR(13)+CHR(10) Dim HC2S3_Split(17) As String * 40 Alias HC2S3_Split(2) = RH_Str Alias HC2S3_Split(6) = TempC_Str Alias HC2S3_Split(17) = HC2S3_SN_Str Public TempC, RH, NBytesReturned Const SensorPort=32 'RH string. 'Temp string. 'HC2S3 serial number string.
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