INSTRUCTION MANUAL CS650 and CS655 Water Content Reflectometers Revision: 5/15 C o p y r i g h t © 2 0 1 1 - 2 0 1 5 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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Precautions DANGER — MANY HAZARDS ARE ASSOCIATED WITH INSTALLING, USING, MAINTAINING, AND WORKING ON OR AROUND TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC. FAILURE TO PROPERLY AND COMPLETELY ASSEMBLE, INSTALL, OPERATE, USE, AND MAINTAIN TRIPODS, TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS INJURY, PROPERTY DAMAGE, AND PRODUCT FAILURE.
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 4. Quickstart .................................................................... 2 5. Overview ...........
Table of Contents 8.3.4.2 Insertion Error ................................................................. 22 8.3.5 Temperature Dependence and Correction .................................. 22 8.3.5.1 Accurate Soil Temperature Measurement ....................... 23 8.4 Water Content Reflectometer User-Calibration ................................ 23 8.4.1 Need for Soil Specific Calibration Equation .............................. 23 8.4.2 User-Derived Calibration Equation .....................................
Table of Contents Tables 6-1. 6-2. 7-1. 8-1. 8-2. 8-3. 8-4. 9-1. B-1. B-2. B-3. B-4. D-1. Size Specifications ............................................................................... 6 Relative Dielectric Permittivity Specifications .................................... 8 CS650 Wiring Code for SDI-12 ......................................................... 11 CS650 Wiring Code for RS-232 and A200 ........................................ 13 Real-Time Measurements ....................................
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CS650 and CS655 Water Content Reflectometers 1. Introduction The CS650 and CS655 are multiparameter smart sensors that use innovative techniques to monitor soil volumetric water content, bulk electrical conductivity, and temperature. They output an SDI-12 signal that many of our dataloggers can measure. The CS650 has 30 cm length rods, whereas the CS655 has 12 cm length rods. This manual uses CS650 to reference model numbers CS650 and CS655.
CS650 and CS655 Water Content Reflectometers 4. Quickstart Short Cut is an easy way to program your datalogger to measure the CS650 and assign datalogger wiring terminals. The following procedures shows using Short Cut to program the CS650. 2 1. Install Short Cut by clicking on the install file icon. Get the install file from either www.campbellsci.com, the ResourceDVD, or find it in installations of LoggerNet, PC200W, PC400, or RTDAQ software. 2.
CS650 and CS655 Water Content Reflectometers 4. Select Datalogger Model and Scan Interval (default of 5 seconds is OK for most applications). Click Next. 5. Under the Available Sensors and Devices list, select the Sensors | Meterological | Soil Moisture | CS650/CS655 Water Content Reflectometer. Four options are available that monitor different parameters. In this tutorial, we’ll select CS650/CS655 Water Content Reflectometer (VWC, EC, T, P, PA, and VR).
CS650 and CS655 Water Content Reflectometers 5. 6. After selecting the sensor, click at the left of the screen on Wiring Diagram to see how the sensor is to be wired to the datalogger. The wiring diagram can be printed out now or after more sensors are added. 7. Select any other sensors you have, then finish the remaining Short Cut steps to complete the program. The remaining steps are outlined in Short Cut Help, which is accessed by clicking on Help | Contents | Programming Steps. 8.
CS650 and CS655 Water Content Reflectometers FIGURE 5-1. CS650 Water Content Reflectometer Volumetric water content information is derived from the probe’s sensitivity to the dielectric permittivity of the medium surrounding the probe stainless-steel rods. The CS650 is configured as a water content reflectometer, with the two parallel rods forming an open-ended transmission line.
CS650 and CS655 Water Content Reflectometers means of RS-232 Tx/Rx. The A200 USB-to-Serial Module allows RS-232 serial communication between a computer and the CS650 by means of Campbell Scientific’s Device Configuration Utility (DevConfig) software. The CS650’s cable can terminate in: Pigtails that connect directly to a Campbell Scientific datalogger (option –PT). Connector that attaches to a prewired enclosure (option –PW). Refer to www.campbellsci.com/prewired-enclosures for more information.
CS650 and CS655 Water Content Reflectometers 6.
CS650 and CS655 Water Content Reflectometers FIGURE 6-1. CS650 and CS655 average current drain FIGURE 6-1 shows average current drain for different measurement rates and quantities of CS650 probes. If the time between measurements is five minutes or longer, average current drain may be approximated at 0.15 milliamps per sensor. 6.2 Operational Specifications TABLE 6-2 provides the operational specifications. TABLE 6-2.
CS650 and CS655 Water Content Reflectometers Volumetric Water Content using Topp Equation (m3/m3) Range Accuracy† 5% to 50% ±3% VWC typical in mineral soils where solution EC ≤3 dS/m Precision‡ ±3% VWC typical in mineral soils where solution EC ≤10 dS/m <0.05% Electrical Conductivity Range Solution EC 0 to 3 dS/m 0 to 8 dS/m Range Bulk EC 0 to 3 dS/m 0 to 8 dS/m Accuracy† ±(5% of reading + 0.05 dS/m) Precision‡ 0.
CS650 and CS655 Water Content Reflectometers The sensitive volume depends on the surrounding media. In soil, the sensitive volume extends approximately 7.5 cm (3 in) from the rods along their length and 4.5 cm (1.8 in) beyond the end of the rods. Consequently, if the probe is buried horizontally closer than 7.5 cm from the soil surface, it will include air above the surface in its measurements and underestimate soil water content.
CS650 and CS655 Water Content Reflectometers 7.3 Datalogger Wiring Our dataloggers typically use SDI-12 to measure the sensor because RS-232 communication requires more control ports per CS650 and RS-232 programming is more complicated than SDI-12 programming. SDI-12 communication also allows up to ten probes to be given different addresses and then share a single control port. TABLE 7-1 shows the SDI-12 wiring for the CS650 water content reflectometer.
CS650 and CS655 Water Content Reflectometers and programming examples for Edlog dataloggers are provided at www.campbellsci.com\old-manuals. The SDI12Recorder() measurement instruction programs CRBasic dataloggers (CR6, CR200(X)-series, CR800-series, CR1000, CR3000, and CR5000) to measure the sensor. This instruction sends a request to the sensor to make a measurement and then retrieves the measurement from the sensor. See Section 8.2, SDI-12 Measurements (p. 19), for more information.
CS650 and CS655 Water Content Reflectometers FIGURE 8-1. A200 Sensor-to-PC Interface A data cable, pn 17648, ships with the A200. This cable has a USB type-A male connector that attaches to a PC’s USB port, and a type B male connector that attaches to the A200’s USB port. TABLE 8-1. CS650 Wiring Code for RS-232 and A200 Color Function A200 Terminal Orange RxD Rx Green TxD Tx Red Power +12 Vdc Black Reference G Clear Shield G 8.1.1.
CS650 and CS655 Water Content Reflectometers 8.1.2 Device Configuration Utility (DevConfig) DevConfig may be downloaded from the Campbell Scientific website, www.campbellsci.com/downloads. Connect the CS650 to the A200 as shown in TABLE 8-1. Connect the PC to the A200 USB port with the supplied USB cable. Launch DevConfig and select CS650 Series from the Device Type menu on the left. Select 9600 from the Baud Rate drop-down menu.
CS650 and CS655 Water Content Reflectometers 8.1.2.1 Settings Editor Tab The Settings Editor tab shows settings stored in the CS650 firmware. Settings that may be modified include User Name, SDI-12 Address, and RS-232 Baud Rate. Attempts to change any of the other settings will result in a “Commit failed. Unrecognized error condition” error message. DevConfig polls the CS650 every two seconds while connected and the results are displayed in the Real-Time Measurements field (TABLE 8-2).
CS650 and CS655 Water Content Reflectometers TABLE 8-2.
CS650 and CS655 Water Content Reflectometers 8.1.2.2 Send OS Tab The Send OS tab is used to update the firmware in the CS650. The firmware is available at www.campbellsci.com/downloads. The file to send will have a filename extension of .a43, such as CS65X.Std.00.36.a43. Sending a new operating system will not affect any of the user-modified settings or probe specific multiplier and offset settings. To download a new operating system, follow the Operating System Download Procedure listed on the Send OS tab.
CS650 and CS655 Water Content Reflectometers TABLE 8-3.
CS650 and CS655 Water Content Reflectometers 8.2 SDI-12 Measurements The CS650 responds to SDI-12 commands M!, M1!, M2!, M3!, ?!, and I!. TABLE 8-4 shows the values returned for each of these commands. See Section 7.3, Datalogger Wiring (p. 11), for SDI-12 wiring details. NOTE This section briefly describes using the SDI-12 commands. Additional SDI-12 information is available at Appendix D, SDI(p. D-1), www.sdi-12.org, or 12 Sensor Support www.youtube.com/user/CampbellScientific. TABLE 8-4.
CS650 and CS655 Water Content Reflectometers 8.2.1 Use of Multiplexers Multiplexers such as Campbell Scientific’s AM16/32B may be used to connect up to 32 CS650 probes to a single control port. When using multiplexers, the simplest configuration is for all probes to have the same SDI-12 address. When multiplexing CS650 probes, the switched 12V channel should be used so that power to the sensor may be turned off under program control before the multiplexer switches to the next channel.
CS650 and CS655 Water Content Reflectometers using an electrical conductivity measurement. A calibration equation converts period and electrical conductivity to bulk dielectric permittivity. The Topp equation is used to convert from permittivity to volumetric water content. 8.3.2 The Topp Equation The relationship between dielectric permittivity and volumetric water content in mineral soils has been described by Topp et al. (1980) in an empirical fashion using a 3rd degree polynomial.
CS650 and CS655 Water Content Reflectometers between soil solution electrical conductivity and soil bulk electrical conductivity. Most expressions of soil electrical conductivity are given in terms of solution conductivity or electrical conductivity from extract since it is constant for a soil. Bulk electrical conductivity increases with water content so comparison of the electrical conductivity of different soils must be at the same water content.
CS650 and CS655 Water Content Reflectometers The effect of temperature on probe electronics is minimal with period average readings varying by less than 0.5% of the 20 °C reading over the range of 10 to 30 °C and less than 2% of the 20 °C reading over the range of –10 to 70 °C. The larger error is caused by the change in dielectric permittivity of soil with temperature. This is mostly due to the high temperature dependence of the permittivity of water, which varies from a value of 88 at 0 °C to 64 at 70 °C.
CS650 and CS655 Water Content Reflectometers Quadratic form: θv(Ka) = C0 + C1*Ka + C2*Ka2 with θv the volumetric water content, Ka the bulk dielectric permittivity of the soil, and Cn , the calibration coefficient. 3rd degree polynomial form: θv(Ka) = C0 + C1*Ka + C2*Ka2 + C3*Ka3 with θv the volumetric water content, Ka the bulk dielectric permittivity of the soil, and Cn , the calibration coefficient. Linear form: θv(Ka) = C0 + C1*Ka0.
CS650 and CS655 Water Content Reflectometers derive a calibration depends on the form of the calibration equation. At least three data sets should be generated to determine whether the linear form is valid. If a polynomial is to be used, four data sets will determine whether the function is a quadratic or third order polynomial. Accuracy requirements may require additional data sets. Consider the expected range of soil water content and include data sets from the highest and lowest expected water contents.
CS650 and CS655 Water Content Reflectometers equilibration is achieved. Collect a set of calibration data values and repeat the water addition procedure again if needed. With soil at equilibrium, record the CS650 permittivity. Take subsamples of the soil using containers of known volume. This is necessary for measurement of bulk density. Copper tubing of diameter ≥ 1 inch and length about 2 inch works well. The tubes can be pressed into the soil surface. It is good to take replicate samples.
CS650 and CS655 Water Content Reflectometers • CS650 connected to datalogger programmed to measure probe permittivity • Cylindrical sampling devices to determine sample volume for bulk density, such as copper tubing with diameter of ≥ 1 inch and length about 2 inches. • Containers and scale to measure soil sample mass • Oven to dry samples (microwave oven can also be used) Data needed for CS650 calibration are the CS650 permittivity output and an independently determined volumetric water content.
CS650 and CS655 Water Content Reflectometers The sample tubes should be pushed evenly into the soil surface. Remove the tube and sample and gently trim the ends of excess soil. Remove excess soil from outside of tube. Remove all the soil from tube to a tray or container of known mass that can be put in oven or microwave. Weigh and record the wet soil mass.
CS650 and CS655 Water Content Reflectometers To obtain mwet, subtract the cylinder empty mass and the container empty mass from the mass of the soil filled cylinder in the tray. Remove all the soil from the cylinder and place this soil in the tray. Dry the samples using oven or microwave methods as described above. To obtain mdry, weigh the tray containing the soil after drying. Subtract tray mass for mdry.
CS650 and CS655 Water Content Reflectometers 9. Maintenance and Troubleshooting The CS650 does not require periodic maintenance. TABLE 9-1 provides troubleshooting information. TABLE 9-1.
CS650 and CS655 Water Content Reflectometers 10. References Ledieu, J., P. De Ridder, P. De Clerck, and S. Dautrebande. 1986. “A method of measuring soil moisture by time-domain reflectometry,” J. Hydrol. 88:319-328. Rhoades, J.D., P.A.C. Raats, and R.J. Prather. 1976. Effects of liquid-phase electrical conductivity, water content and surface conductivity on bulk soil electrical conductivity. Soil Sci. Soc. Am. J., 40: 651-653. Rhoades, J.D., N.A. Manteghi, P.J. Shouse, W.J. Alves. 1989.
CS650 and CS655 Water Content Reflectometers 32
Appendix A. Importing Short Cut Code into a Program Editor This tutorial shows: • How to import a Short Cut program into a program editor for additional refinement • How to import a wiring diagram from Short Cut into the comments of a custom program Short Cut creates files that can be imported into either CRBasic Editor program editor. These files normally reside in the C:\campbellsci\SCWin folder and have the following extensions: • • • • • • • .DEF (wiring and memory usage information) .
Appendix A. Importing Short Cut Code After pasting, edit the information such that a ' character (single quotation mark) begins each line. This character instructs the datalogger compiler to ignore the line when compiling the datalogger code.
Appendix B. Example Programs B.1 CR1000 Programs B.1.1 CR1000 with One CS650 Probe This CRBasic example program measures one CS650 probe on a CR1000 every 15 minutes, storing hourly averages of volumetric water content, electrical conductivity, and soil temperature and samples of permittivity, period average and voltage ratio. The CS650 has an SDI-12 address of 0. Wiring for the example is shown in TABLE B-1. TABLE B-1.
Appendix B. Example Programs Public CS650(6) Public CS650_2(6) DataTable (DatoutCS650,1,-1) DataInterval (0,60,Min,2) Average (3,CS650(1),FP2,False) Sample(3,CS650(4),IEEE4) Average (3,CS650_2(1),FP2,False) Sample(3,CS650_2(4),IEEE4) EndTable BeginProg Scan (15,Min,0,0) SDI12Recorder (CS650(1),1,0,"M3!",1.0,0) SDI12Recorder (CS650_2(1),1,1,"M3!",1.0,0) CallTable DatoutCS650 'Call Data Table NextScan EndProg B.1.
Appendix B. Example Programs Dim LCount Public CS650(12,6) DataTable (DatoutCS650,1,-1) DataInterval (0,60,Min,2) Average (72,CS650(),IEEE4,False) EndTable BeginProg Scan (15,Min,0,0) PortSet(2,1) 'Turn AM16/32 Multiplexer On Delay(0,150,mSec) LCount=1 SubScan(0,uSec,12) PulsePort(3,10000) 'Switch to next AM16/32 channel SW12 (1 ) 'Apply power to CS650 Delay (0,3,Sec) 'Wait three seconds for probe to warm up SDI12Recorder (CS650(LCount,1),1,0,"M!",1.
Appendix B.
Appendix C. Discussion of Soil Water Content The water content reflectometer measures volumetric water content. Soil water content is expressed on a gravimetric and a volumetric basis. To obtain the independently determined volumetric water content, gravimetric water content must first be measured. Gravimetric water content (θg) is the mass of water per mass of dry soil. It is measured by weighing a soil sample (mwet), drying the sample to remove the water, then weighing the dried soil (mdry).
Discussion of Soil Water Content C-2
Appendix D. SDI-12 Sensor Support D.1 SDI-12 Command Basics SDI-12 commands have three components: Sensor address (a) – a single character, and is the first character of the command. CS650 sensors are usually assigned a default address of zero unless option –VS is selected at the time of ordering. Sensors with the –VS option are addressed with the last digit of the probe’s serial number.
Appendix D. SDI-12 Sensor Support command is 0A2!. The sensor responds with the new address b, which in this case is 2. Send Identification Command (aI!) Sensor identifiers are requested by issuing command aI!. The reply is defined by the sensor manufacturer, but usually includes the sensor address, SDI-12 version, manufacturer’s name, and sensor model information. Serial number or other sensor specific information may also be included.
Appendix D. SDI-12 Sensor Support Send Data Command (aDv!) This command requests data from the sensor. It is normally issued automatically by the datalogger after measurement commands aMv!. In transparent mode, the user asserts this command to obtain data. If the expected number of data values are not returned in response to an aD0! command, the data logger issues aD1!. The limiting constraint is that the total number of characters that can be returned to an aD0! command is 35 characters.
Appendix D. SDI-12 Sensor Support D.2.2 CR200(X) Series Datalogger Example 1. Connect a single CS650 to the datalogger as follows: • • • Green to Control Port C1/SDI12 Black, Orange, Clear to G Red to Battery + 2. In the LoggerNet Connect screen navigate to the Datalogger menu and select Terminal Emulator. The “Terminal Emulator” window will open. In the Select Device menu, located in the lower left-hand side of the window, select the CR200Series station. 3. Click on the Open Terminal button. 4.
Appendix D. SDI-12 Sensor Support D.2.3 CR1000 Datalogger Example 1. Connect a single CS650 to the datalogger as follows: • • • Green to Control Port C1 Black, Orange, Clear to G Red to 12V 2. In the LoggerNet Connect screen navigate to the Datalogger menu and select Terminal Emulator. The “Terminal Emulator” window will open. In the Select Device menu, located in the lower left-hand side of the window, select the CR1000 station. 3. Click on the Open Terminal button. 4.
Appendix D.
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