Campbell CS616 Instruction Manual
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Campbell CS616 Instruction Manual

Water content reflectometers
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CS616 and CS625
Water Content Reflectometers
Revision: 2/16
C o p y r i g h t
©
2 0 0 2 - 2 0 1 6
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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Summary of Contents for Campbell CS616

  • Page 1 CS616 and CS625 Water Content Reflectometers Revision: 2/16 C o p y r i g h t © 2 0 0 2 - 2 0 1 6 C a m p b e l l S c i e n t i f i c ,...
  • Page 3 Limited Warranty “Products manufactured by CSI are warranted by CSI to be free from defects in materials and workmanship under normal use and service for twelve months from the date of shipment unless otherwise specified in the corresponding product manual. (Product manuals are available for review online at www.campbellsci.com.) Products not manufactured by CSI, but that are resold by CSI, are warranted only to the limits extended by the original manufacturer.
  • Page 4 SCIENTIFIC, INC., phone (435) 227-9000. After an application engineer determines the nature of the problem, an RMA number will be issued. Please write this number clearly on the outside of the shipping container. Campbell Scientific’s shipping address is: CAMPBELL SCIENTIFIC, INC.
  • Page 5 Periodically (at least yearly) check electrical ground connections. • WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC.

  • Page 7: Table Of Contents

    Orientation ................... 6 Potential Problems with Improper Insertion ........6 Wiring ....................7 Datalogger Programming ..............7 7.4.1 CS616 CRBasic Programming............8 7.4.2 CS625 CRBasic Programming............8 8. Operation ..............9 Water Content Reflectometer Method for Measuring Volumetric Water Content ................... 9 8.1.1...
  • Page 8 B. Importing Short Cut Code Into CRBasic Editor ... B-1 C. Example Programs ..........C-1 CS616 Programs ................C-1 C.1.1 CR1000 Program for Measuring Eight CS616 Probes ..... C-1 C.1.2 CR1000/Multiplexer Program for Measuring 48 CS616 Probes ................... C-3 CS625 Programs ................C-5 C.2.1 CR200(X) Program for Measuring Four CS625 Probes ..

  • Page 9: Introduction

    Introduction The CS616 Water Content Reflectometer is an improved version of the CS615 Water Content Reflectometer. The CS625 is a modified CS616 for use with the CR200(X)-series dataloggers. The difference between the CS616 and the CS625 is the output voltage level.

  • Page 10: Quickstart

    CS616 and CS625 Water Content Reflectometers QuickStart Short Cut is an easy way to program your datalogger to measure the CS616 or CS625 probe and assign datalogger wiring terminals. Short Cut is available as a download on www.campbellsci.com and the ResourceDVD. It is included in installations of LoggerNet, PC200W, PC400, or RTDAQ.
  • Page 11 CS616 and CS625 Water Content Reflectometers Under the Available Sensors and Devices list, select the Sensors | Soil Moisture folder. Select CS616 Water Content Reflectometer. Click to move the selection to the Selected device window. It defaults to measuring the sensor hourly. This can be changed by clicking the Measure Sensor box and selecting Every Scan.

  • Page 12: Overview

    • Probe rods can be inserted from the surface or buried at any • orientation to the surface CS616 compatible with Campbell Scientific CRBasic dataloggers: • CR6, CR80, CR850, CR1000, CR3000, and CR5000 CS625 compatible with Campbell Scientific CRBasic dataloggers: •...

  • Page 13: Dimensions

    Operational Details The accuracy specification for the volumetric water content measurement using the CS616/CS625 probes is based on laboratory measurements in a variety of soils and over the water content range air dry to saturated. The soils were typically sandy loam and coarser. Silt and clay were present in some of...

  • Page 14: Installation

    CS616 and CS625 Water Content Reflectometers Resolution is the minimum change in the dielectric permittivity that can reliably be detected by the water content reflectometer. The CS616 or CS625 is typically used to measure soil volumetric water content. Precision describes the repeatability of a measurement. It is determined for the CS616 and CS625 by taking repeated measurements in the same material.

  • Page 15: Wiring

    CS616 and CS625 Water Content Reflectometers Wiring TABLE 7-1. Datalogger/Reflectometer Wiring. Color Function Datalogger Connection +12 V +12 V green output SE analog or universal channel orange enable control port ⏚ or AG black signal ground clear power ground Both the black and clear wires must be grounded as shown in NOTE TABLE 7-1.

  • Page 16: Cs616 Crbasic Programming

    7.4.1 CS616 CRBasic Programming The output of the CS616 is a square wave with amplitude of ±0.7 Vdc and a frequency that is dependent on the dielectric constant of the material surrounding the probe rods. The CRBasic instruction CS616() is used by the CR6, CR800, CR850, CR1000, CR3000, and CR5000 dataloggers to measure the CS616 output period.

  • Page 17: Operation

    The fundamental principle for CS616/CS625 operation is that an electromagnetic pulse will propagate along the probe rods at a velocity that is dependent on the dielectric permittivity of the material surrounding the line.

  • Page 18: Response Curves

    0% to 50% VWC. Output period (microseconds) calibration data linear fit quadratic fit FIGURE 8-1. CS616 and CS625 linear and quadratic calibrations derived from loam soil FIGURE compares the CS616 response in the FIGURE loam soil to a...

  • Page 19: Calibration Equations

    0.75 dS m –1 . The CS625 response is similar. FIGURE 8-2. CS616 response for different soil types The compacted soil response shows the effect of compaction and high clay content. The signal attenuation caused by compaction or high clay content causes an offset in the response as shown by the near-parallel curves at water contents above 10%.

  • Page 20: Linear Versus Quadratic Calibration Differences

    FIGURE shows the difference between the linear and the quadratic calibration forms over the typical range. A CS616/CS625 output period of 16 microseconds is about 1.2% VWC and 32 microseconds is 44.9%. The linear calibration is within ± 2.7% VWC of the quadratic. The linear calibration underestimates water content at the wet and dry ends of the range and overestimates it by up to about 2.6 % VWC at about 20% VWC.

  • Page 21: Operating Range

    The quality of soil water measurements which apply electromagnetic fields to wave guides is affected by soil electrical conductivity. The propagation of electromagnetic fields in the configuration of the CS616/CS625 is predominantly affected by changing dielectric constant due to changing water content, but it is also affected by electrical conductivity.

  • Page 22: Soil Organic Matter, Clay Content, And Soil Bulk Density

    CS616 and CS625 Water Content Reflectometers also discusses soil properties related to CS616/CS625 operation such as clay content and compaction. The above equation is presented here to show the relationship between soil solution electrical conductivity and soil bulk electrical conductivity.

  • Page 23: Signal Attenuation Error

    When the reflection of the applied signal from the end of the rods is detected by the CS616/CS625 circuit, another pulse is applied. The time between pulses depends on the propagation time, and the associated period is empirically related to volumetric water content.

  • Page 24: Water Content Reflectometer User-Calibration

    CS616 and CS625 Water Content Reflectometers Water Content Error with Temperature Soil Temperature (C) Water Content = 30% Water Content = 12% FIGURE 8-4. Percent volumetric water content error adjusted with temperature correction equation Water Content Reflectometer User-Calibration 8.2.1 Signal Attenuation in Conductive Soils and Need for Site-Specific...

  • Page 25: User-Derived Calibration Equation

    8.2.3 Collecting Laboratory Data for Calibration Water content reflectometer data needed for CS616/CS625 calibration are the CS616/CS625 output period (microseconds) and an independently determined volumetric water content. From this data, the probe’s response to changing water content can be described by a quadratic calibration equation of the form θ...
  • Page 26 , the intercept; and C , the slope. Required equipment: CS616/CS625 connected to datalogger programmed to measure output period Cylindrical sampling devices to determine sample volume for bulk density; for example, copper tubing of diameter ≥ 1 inch and length about...
  • Page 27 The time required for equilibration depends on the amount of water added and the hydraulic properties of the soil. Equilibration can be verified by frequently observing the CS616/CS625 period output. When period is constant, equilibration is achieved. Collect a set of calibration data values and repeat the water addition procedure again if needed.

  • Page 28: Collecting Field Data For Calibration

    θ ρ × bulk The average water content for the replicates and the recorded CS616/CS625 period are one datum pair to be used for the calibration curve fit. 8.2.4 Collecting Field Data for Calibration Required equipment CS616/CS625 connected to datalogger programmed to measure probe...
  • Page 29 However, intentionally changing water content in soil profiles can be difficult. A vertical face of soil can be formed with a shovel. If the CS616/CS625 is to be used within about 0.5 meters of the surface, the probe can be inserted into the face and water added to the surface with percolation.

  • Page 30: Calculations

    ρ × bulk The average water content for the replicates and the recorded CS616 period are one datum pair to be used for the calibration curve fit. 8.2.5 Calculations The empty cylinders used for core sampling should be clean; both empty weight and volume are measured and recorded.

  • Page 31: Maintenance

    ρ × bulk Maintenance The CS616/CS625 does not require periodic maintenance. 10. References 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.
  • Page 32 CS616 and CS625 Water Content Reflectometers...
  • Page 33 Appendix A. 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.

  • Page 34: Discussion Of Soil Water Content

    Appendix A. Discussion of Soil Water Content...

  • Page 35: Importing Short Cut Code Into Crbasic Editor

    Appendix B. Importing Short Cut Code Into CRBasic 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 •...
  • Page 36 Appendix B. Importing Short Cut Code Into CRBasic Editor...

  • Page 37: Example Programs

    C.1 CS616 Programs C.1.1 CR1000 Program for Measuring Eight CS616 Probes The following CR1000 program uses the CS616() instruction to measure eight CS616 probes connected to the CR1000 datalogger (TABLE C-1). Although this example is for the CR1000, other CRBasic dataloggers are programmed similarly.
  • Page 38 Appendix C. Example Programs CRBasic Example C-1. CR1000 Program for Measuring Eight CS616 Probes 'Declare Public and Dim Variables Public batt_volt Public Panel_temp Public Period (8) Public VWC (8) Public Flag (1) 'Declare Constants 'CS616 Default Calibration Constants const a0= -0.0663 const a1= -0.0063...

  • Page 39: Cr1000/Multiplexer Program For Measuring 48 Cs616 Probes

    C.1.2 CR1000/Multiplexer Program for Measuring 48 CS616 Probes The following CR1000 program uses the AM16/32-series multiplexer to measure 48 CS616 probes connected in the 4x16 configuration; wiring is provided in TABLE C-2). The program also measures datalogger battery voltage and temperature.
  • Page 40 Appendix C. Example Programs CRBasic Example C-2. CR1000/Multiplexer Program for Measuring 48 CS616 Probes 'Declare Public and Dim Variables Public batt_volt Public Panel_temp Public Period (48) Public VWC (48) Public Flag (1) 'Declare Constants 'CS616 Default Calibration Constants const a0= -0.0663 const a1= -0.0063...

  • Page 41: Cs625 Programs

    Appendix C. Example Programs C.2 CS625 Programs C.2.1 CR200(X) Program for Measuring Four CS625 Probes This CR200X program measures volumetric water content with four CS625 probes; TABLE provides wiring. The average hourly readings are saved in final storage every 4 hours. TABLE C-3.

  • Page 42: Cr200(X) Program With Temperature Correction

    Appendix C. Example Programs C.2.2 CR200(X) Program with Temperature Correction This CR200X program measures temperature with 109 probe and uses the 109 temperature to correct the period for one CS625. The standard calibration equation is used to convert temperature-corrected period to volumetric water content.

  • Page 43: C-4. Cr200(X) Program With Temperature Correction

    Appendix C. Example Programs CRBasic Example C-4. CR200(X) Program with Temperature Correction 'CR200(X) program to read one 109 temperature probe and 1 CS625. 'Use temperature to correct CS625 period. 'Standard calibration is used to convert CS625 output 'period to volumetric water content. 'Sensors are read hourly and average water content and 'temperature are written to storage every 4 hours.
  • Page 44 Appendix C. Example Programs...
  • Page 46 Santo Domingo, Heredia 40305 SOUTH AFRICA COSTA RICA • cleroux@csafrica.co.za • info@campbellsci.cc www.campbellsci.co.za www.campbellsci.cc Campbell Scientific Southeast Asia Co., Ltd. Campbell Scientific Ltd. 877/22 Nirvana@Work, Rama 9 Road Campbell Park Suan Luang Subdistrict, Suan Luang District 80 Hathern Road Bangkok 10250...

This manual is also suitable for:

Cs625

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