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: 10/12
C o p y r i g h t
©
2 0 0 2 - 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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Summary of Contents for Campbell CS616

  • Page 1 CS616 and CS625 Water Content Reflectometers Revision: 10/12 C o p y r i g h t © 2 0 0 2 - 2 0 1 2 C a m p b e l l S c i e n t i f i c ,...
  • Page 3 Campbell pricelist or product manual. Products not manufactured, but that are re-sold by Campbell, are warranted only to the limits extended by the original manufacturer. Batteries, fine-wire thermocouples, desiccant, and other consumables have no warranty.
  • Page 4 SCIENTIFIC, INC., phone (435) 227-9000. After an applications 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: Table Of Contents

    6. Installation ..............4 Orientation ...................4 Potential Problems with Improper Insertion.........4 Wiring ....................5 Datalogger Instructions and Programming...........6 6.4.1 Measuring the CS616 Using CRBasic ..........6 6.4.1.1 CS616 Sample CRBasic Program 1 ........7 6.4.1.2 CS616 Sample CRBasic Program 2 ........9 6.4.2 Measuring CS625 Output Using CR200(X) PeriodAvg Instruction................11...
  • Page 6 CS616 and CS625 linear and quadratic calibrations derived from loam soil..................27 7-2. CS616 and CS625 response for low EC loam with bulk density 1.4 g cm , a low EC sandy clay loam with bulk density 1.6 g cm , and a high EC sandy clay loam with bulk density 1.6 g cm...
  • Page 7 Table of Contents 7-3. Calibration coefficients for sandy clay loam with bulk density 1.6 g cm and electrical conductivity at saturation 0.75 dS m for both linear and quadratic forms........30...
  • Page 8 Table of Contents...

  • Page 9: Introduction

    Overview The CS616 output is a square wave output and can be connected to our CR800, CR850, CR1000, CR3000, CR5000, CR510, CR10X, and CR23X dataloggers. A special CS616 datalogger instruction is used to measure the probe output...

  • Page 10: Sensors Specifications

    Datalogger instructions for period averaging can also be used. The CS625 output is a square wave output and can be connected to Campbell Scientific CR200(X) series dataloggers. A CRBasic program using Period Averaging is used to measure the probe output period and convert to volumetric water content using calibration equations.

  • Page 11: Dimensions

    The CS616/CS625 is Πcompliant with performance criteria available upon request. RF emissions are below EN55022 limits if the CS616/CS625 is enabled less than 0.6 ms and measurements are made at a 1 Hz (1 per second) or slower frequency. The...

  • Page 12: Operational Details

    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 13: Wiring

    CS616 and CS625 Water Content Reflectometers In some applications, installation can be improved by using the CS650G insertion guide tool. The CS650G is inserted into the soil and then removed. This makes proper installation of the water content reflectometer easier in dense or rocky soils.

  • Page 14: Datalogger Instructions And Programming

    Short Cut software. You do not need to read this section if using Short Cut. 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.

  • Page 15: Cs616 Sample Crbasic Program 1

    MeasPerPort: The MeasPerPort parameter is the number of control ports to be used to control the CS616 sensor(s). If Reps is set to 4, MeasPerPort = 4 will result in the same port being used for all measurements. MeasPerPort = 1 will result in four sequential ports being used for the measurements.
  • Page 16 CS616 and CS625 Water Content Reflectometers Wiring for CRBasic Program Example 1 CS616 CR1000 CS616#1_Green CS616#2_Green CS616#3_Green CS616#4_Green #1,2,3,4_Orange #1,2,3,4_Blk & Clear #1,2,3,4_Red 12 V CS616#5_Green CS616#6_Green CS616#7_Green CS616#8_Green #5,6,7,8_Orange #5,6,7,8_Blk & Clear #5,6,7,8_Red 12 V Note: All CS616 “12V_Red”...

  • Page 17: Cs616 Sample Crbasic Program 2

    EndProg 6.4.1.2 CS616 Sample CRBasic Program 2 The following CR1000 program uses the AM16/32-series multiplexer to measure 48 CS616 probes connected in the 4x16 configuration. The program also measures datalogger battery voltage and temperature. Wiring for CRBasic Program Example 2...
  • Page 18 'Set flag 1 High every 30 min (Note: User can manually set flag 1 high/low) If IfTime (0,30,min) Then flag (1) = high '+++++++++++++++++++++++++++ If Flag (1) = high Then 'measure 48ea CS616 probes on AM16/32 in (4x16) mode PortSet (4,1) 'Set Mux Reset line High 'Set sub scan loop counter...

  • Page 19: Measuring Cs625 Output Using Cr200(X) Periodavg Instruction

    CS616 and CS625 Water Content Reflectometers 6.4.2 Measuring CS625 Output Using CR200(X) PeriodAvg Instruction The PeriodAvg() instruction is used to measure the period (in microseconds) or the frequency (in kHz) of a signal on a single-ended channel. This instruction can be used to measure the CS625 Water Content Reflectometer.

  • Page 20: Sample Programs For Cs625

    CS616 and CS625 Water Content Reflectometers 6.4.3 Sample Programs for CS625 TABLE 6-2. CS625 Sample Programs Sample Program Number Program Description Measure volumetric water content with 4 CS625 hourly. Store average hourly readings to final storage every 4 hours. Measure temperature with 109 probe and use the 109 temperature to correct the period for 1 CS625.

  • Page 21: Cs625 Sample Program 2

    CS616 and CS625 Water Content Reflectometers 'Main Program BeginProg Scan (1,hr) SWBatt (1) PeriodAvg (period(1),1,0,10,10,C1,1,0) PeriodAvg (period(2),2,0,10,10,C1,1,0) PeriodAvg (period(3),3,0,10,10,C1,1,0) PeriodAvg (period(4),4,0,10,10,C1,1,0) For i=1 To 4 vwc(i) = a0 + a1*period(i) + a2*period(i)^2 Next i CallTable ofile NextScan EndProg 6.4.3.2 CS625 Sample Program 2 Measure temperature with 109 probe and use the 109 temperature to correct the period for 1 CS625.

  • Page 22: Measuring Cs616 Using Edlog

    When Reps is greater than 1, this entry is the channel for the first CS616. Port: Enter an integer to specify the control port that will be used to enable the CS616 sensor. For the CR510, only C1 can be used to enable a CS616.

  • Page 23: Using Edlog Instruction 27 (Period Averaging)

    With a multiplier of 1 and an offset of 0, P138 returns the period in microseconds. 6.4.4.2 Using Edlog Instruction 27 (Period Averaging) See Section 6.4.5.2, CS616 Sample Edlog Program 2, for example on using Instruction 27. 1: Period Average (SE) (P27)
  • Page 24 CS616 and CS625 Water Content Reflectometers Code Max. Freq. 8 kHz @ 2 mV peak-to-peak 20 kHz @ 3 mV peak-to-peak 50 kHz @ 12 mV peak-to-peak 200 kHz @ 2 V peak-to-peak Where: x = 0 Output period in microseconds...

  • Page 25: Sample Edlog Programs For Cs616

    Hourly, measure datalogger battery voltage, internal temperature and 48 CS616 probes using AM16/32 multiplexer. 6.4.5.1 CS616 Sample Edlog Program 1 Set Flag 1 to read output of one CS616 using CR10X instruction 138 and convert output period to volumetric water content CS616...

  • Page 26: Cs616 Sample Edlog Program 2

    1 period 1 0 1 2 VWC 1 0 1 6.4.5.2 CS616 Sample Edlog Program 2 Every 5 minutes, measure CS616 output period using instruction 27 and convert to volumetric water content. Write hourly average to datalogger final storage. CS616...
  • Page 27 CS616 and CS625 Water Content Reflectometers ;{CR10X} *Table 1 Program 01: 300 Execution Interval (seconds) 1: Do (P86) ;Enable/Turn On the CS616 probe. 1: 41 Set Port 1 High 2: Period Average (SE) (P27) 1: 1 Reps 2: 4 200 kHz Max Freq @ 2 V Peak to Peak, Period Output...

  • Page 28: Cs616 Sample Edlog Program 3

    CS616 and CS625 Water Content Reflectometers 6.4.5.3 CS616 Sample Edlog Program 3 Read datalogger battery voltage and 3 CS616s hourly. CS616 enable wires are connected to sequential datalogger control ports for automatic incrementing. Convert CS616 period to volumetric water content. Write average of hourly readings to final storage every 4 hours.

  • Page 29: Cs616 Sample Edlog Program 4

    107 black Excitation 1 (E1) 107 purple Analog Ground (AG) 107 clear Ground (G) The CS616 red leads are connected to 12 Vdc and the blacks and shields are connected to ground. ;{CR10X} *Table 1 Program 01: 60 Execution Interval (seconds) ;set reference temperature for temperature correction...
  • Page 30 4: 3 Loc [ CS616 5: 1.0 Mult 6: 0.0 Offset ;The following four instructions correct CS616 period for soil temperature ;The corrected period is stored as variable NewCS616. 5: Polynomial (P55) 1: 1 Reps 2: 3 X Loc [ CS616...

  • Page 31: Cs616 Sample Edlog Program 5

    7 WaterCont 1 1 1 6.4.5.5 CS616 Sample Edlog Program 5 Hourly, measure datalogger battery voltage, internal temperature and 48 CS616 probes. The AM16/32-series multiplexer slide switch on the top panel is set to 4X16. Can execute measurement sequence manually by setting Flag 1 high.
  • Page 32 CS616 and CS625 Water Content Reflectometers Sensor lead AM16/32 CR10X CS616-47 green CS616-48 green CS616-46,47,48 COM ODD H COM ODD L COM EVEN H COM EVEN L ;{CR10X} *Table 1 Program 01: 60 Execution Interval (seconds) 1: Batt Voltage (P10) ;Measure battery voltage...
  • Page 33 CS616 and CS625 Water Content Reflectometers 9: CS616 Water Content Reflectometer (P138) ;Measure Period on 3ea CS616 1: 3 Reps 2: 1 SE Channel 3: 13 All reps use C3 4: 3 -- Loc [ Period_1 ] 5: 1.0 Mult 6: 0.0...

  • Page 34: The Water Content Reflectometer Method For Measuring Volumetric Water Content

    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 35: Cs616 And Cs625 Linear And Quadratic Calibrations Derived From Loam Soil

    ≤ 0.5 dS m and bulk density ≤ 1.55 g cm in a measurement range of 0% VWC to 50% VWC. Output period (microseconds) calibration data linear fit quadratic fit FIGURE 7-1. CS616 and CS625 linear and quadratic calibrations derived from loam soil...

  • Page 36: Cs616 And Cs625 Response For Low Ec Loam With Bulk Density 1.4 G

    EC soil low EC, compacted soil high EC, compacted soil FIGURE 7-2. CS616 and CS625 response for low EC loam with bulk density 1.4 g cm , a low EC sandy clay loam with bulk density 1.6 g , and a high EC sandy clay loam with bulk density 1.6 g cm The compacted soil response shows the effect of compaction and high clay content.

  • Page 37: Calibration Equations

    FIGURE 7-3 shows the difference between the linear and quadratic calibration forms over the typical range. A CS616/CS625 output period of 16 microseconds is about 2% VWC and 32 microseconds is 47.25%. The linear calibration is within ± 1.25% VWC of the quadratic with underestimation of water content at wet and dry ends of the range and overestimates by up to about 1.2 % VWC at about 20% VWC.

  • Page 38: Difference In % Volumetric Water Content Between Linear And Quadratic Forms Of Calibrations

    CS616 and CS625 Water Content Reflectometers linear/quadratic cal differences VWC10percent VWC40percent CS616/CS625 output period (microseconds) FIGURE 7-3. Difference in % volumetric water content between linear and quadratic forms of calibrations The linear and quadratic coefficients for the sandy clay loam data in FIGURE 7-3 follow and can be used in similar soils.

  • Page 39: Operating Range

    See Rhoades et al., 1989 for a form of this equation which accounts for mobile and immobile water. This publication 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 40: Soil Organic Matter, Clay Content And Soil Bulk Density

    The propagation of electromagnetic energy along the probe rods depends on the dielectric properties of the medium. When the reflection of the applied signal from the end of the rods is detected by the CS616/CS625 circuit,...

  • Page 41: Temperature Dependence And Correction

    Temperature Dependence and Correction The error in measured volumetric water content caused by the temperature dependence of the CS616/CS625 is shown in FIGURE 7-4. The magnitude of the temperature sensitivity changes with water content. Laboratory measurements were performed at various water contents and over the temperature range from 10°C to 40°C to derive a temperature correction for...

  • Page 42: 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 7-4. Percent volumetric water content error corrected for by temperature correction equation Water Content Reflectometer User-Calibration Signal Attenuation in Conductive Soils and Need for Site-...

  • Page 43: The User-Derived Calibration Equation

    Note from FIGURE 7-1 and FIGURE 7-2 that the calibration function describing the CS616/CS625 response to changing water content is always concave up. If calibration data suggests a different shape, there may be a problem with the data or method.
  • Page 44 , the intercept; and C , the slope. Required equipment: 1. CS616/CS625 connected to datalogger programmed to measure output period 2. Cylindrical sampling devices to determine sample volume for bulk density; for example, copper tubing of diameter ≥ 1 in. and length about 2 in.
  • Page 45 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 46: Collecting Field Data For Calibration

    θ θ ρ 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. Collecting Field Data for Calibration Required equipment 1. CS616/CS625 connected to datalogger programmed to measure probe output period 2.
  • Page 47 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 48: Calculations

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

  • Page 49: Maintenance

    θ 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 50 CS616 and CS625 Water Content Reflectometers...

  • Page 51: Appendix

    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 52: Discussion Of Soil Water Content

    Appendix A. Discussion of Soil Water Content...
  • Page 54 Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA)

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