Campbell Scientific CS616, CS625 User Manual

INSTRUCTION MANUAL

CS616 and CS625

Campbell Scientific, Inc.

Water Content Reflectometers

Revision: 2/14

Warranty

“PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified in the corresponding 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. Campbell's obligation under this warranty is limited to repairing or replacing (at Campbell's option) defective products, which shall be the sole and exclusive remedy under this warranty. The customer shall assume all costs of removing, reinstalling, and shipping defective products to Campbell. Campbell will return such products by surface carrier prepaid within the continental United States of America. To all other locations, Campbell will return such products best way CIP (Port of Entry) INCOTERM® 2010, prepaid. This warranty shall not apply to any products which have been subjected to modification, misuse, neglect, improper service, accidents of nature, or shipping damage. This warranty is in lieu of all other warranties, expressed or implied. The warranty for installation services performed by Campbell such as programming to customer specifications, electrical connections to products manufactured by Campbell, and product specific training, is part of Campbell’s product warranty. CAMPBELL EXPRESSLY DISCLAIMS AND EXCLUDES ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Campbell is not liable for any special, indirect, incidental, and/or consequential damages.”

Assistance

Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs for customers within their territories. Please visit

www.campbellsci.com to determine which Campbell Scientific company serves

your country.

To obtain a Returned Materials Authorization (RMA), contact CAMPBELL 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. RMA#_____ 815 West 1800 North Logan, Utah 84321-1784

For all returns, the customer must fill out a "Statement of Product Cleanliness and Decontamination" form and comply with the requirements specified in it. The form is available from our web site at www.campbellsci.com/repair. A completed form must be either emailed to repair@campbellsci.com or faxed to (435) 227-9106. Campbell Scientific is unable to process any returns until we receive this form. If the form is not received within three days of product receipt or is incomplete, the product will be returned to the customer at the customer's expense. Campbell Scientific reserves the right to refuse service on products that were exposed to contaminants that may cause health or safety concerns for our employees.

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. Overview ...................................................................... 1

5. Specifications ............................................................. 2

5.1 Dimensions ........................................................................................... 3

5.2 Weight .................................................................................................. 3

5.3 Electrical Specifications ....................................................................... 3

5.4 Operational Details ............................................................................... 4

6. Installation ................................................................... 4

6.1 Orientation ........................................................................................... 4

6.2 Potential Problems with Improper Insertion ......................................... 4

6.3 Wiring .................................................................................................. 5

6.4 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 ................................................................................ 10

6.4.3 Sample Programs for CS625 ....................................................... 11

6.4.3.1 CS625 Sample Program 1 ................................................ 11

6.4.3.2 CS625 Sample Program 2 ................................................ 12

6.4.4 Measuring CS616 Using Edlog ................................................... 13

6.4.4.1 Using Edlog Instruction 138 ............................................. 13

6.4.4.2 Using Edlog Instruction 27 (Period Averaging) ............... 14

6.4.5 Sample Edlog Programs for CS616 ............................................ 16

6.4.5.1 CS616 Sample Edlog Program 1 ...................................... 16

6.4.5.2 CS616 Sample Edlog Program 2 ...................................... 17

6.4.5.3 CS616 Sample Edlog Program 3 ...................................... 18

6.4.5.4 CS616 Sample Edlog Program 4 ...................................... 19

6.4.5.5 CS616 Sample Edlog Program 5 ...................................... 21

7. The Water Content Reflectometer Method for

Measuring Volumetric Water Content .................. 24

7.1 Description of Measurement Method ................................................. 24

7.2 Response Curves ................................................................................ 24

7.3 Calibration Equations ......................................................................... 27

Table of Contents

7.4 Operating Range ................................................................................ 29

7.4.1 Soil Electrical Conductivity ....................................................... 29

7.4.2 Soil Organic Matter, Clay Content and Soil Bulk Density ......... 29

7.5 Error Sources in Water Content Reflectometer Measurement .......... 30

7.5.1 Probe-to-Probe Variability Error ................................................ 30

7.5.2 Insertion Error ............................................................................ 30

7.5.3 Signal Attenuation Error ............................................................ 30

7.6 Temperature Dependence and Correction ......................................... 31

8. Water Content Reflectometer User-Calibration ...... 32

8.1 Signal Attenuation in Conductive Soils and Need for Site-Specific

Calibration ..................................................................................... 32

8.2 The User-Derived Calibration Equation ............................................ 33

8.3 Collecting Laboratory Data for Calibration ....................................... 34

8.4 Collecting Field Data for Calibration ................................................ 36

8.5 Calculations ....................................................................................... 38

9. Maintenance .............................................................. 39

10. References ................................................................. 39

Appendix

Discussion of Soil Water Content ......................... A-1

Figures

6-1. CS616 Water Content Reflectometer .................................................. 5

6-2. CS625 Water Content Reflectometer .................................................. 5

7-1. CS616 and CS625 linear and quadratic calibrations derived from

loam soil ......................................................................................... 25

7-2. CS616 and CS625 response for low EC loam with bulk density

1.4 g cm cm cm

7-3. Difference in % volumetric water content between linear and

quadratic forms of calibrations ...................................................... 28

7-4. Percent volumetric water content error corrected for by

temperature correction equation ..................................................... 32

-3

, a low EC sandy clay loam with bulk density 1.6 g

-3

, and a high EC sandy clay loam with bulk density 1.6 g

-3

. ............................................................................................... 26

Tables

6-1. CS616/625 wiring code. ......................................................................... 5

6-2. CS625 Sample Programs ...................................................................... 11

6-3. CS616 Sample Edlog Programs ............................................................ 16

7-1. Standard calibration coefficients for linear and quadratic forms. ......... 27

7-2. Calibration coefficients for sandy clay loam with bulk density 1.6 g

7-3. Calibration coefficients for sandy clay loam with bulk density 1.6 g

-3

and electrical conductivity at saturation 0.4 dS m-1 for both

linear and quadratic forms. ............................................................ 28

-3

and electrical conductivity at saturation 0.75 dS m-1 for

both linear and quadratic forms. .................................................... 28

CS616 and CS625 Water Content Reflectometers

1. 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 Campbell Scientific CR200(X) series dataloggers. The difference between the CS616 and the CS625 is the output voltage level.

Both water content reflectometers are designed to measure volumetric water content of soils or other porous media. The water content information is derived from the probe sensitivity to the dielectric constant of the medium surrounding the probe rods.

Before installing the CS616 or CS625, please study

• Section 2, Cautionary Statements

• Section 3, Initial Inspection

2. Cautionary Statements

• Although the CS616/CS625 is rugged, it should be handled as precision

scientific instrument.

• External RF sources can affect CS616/CS625 measurements.

Consequently, the CS616/CS625 circuitry should be located away from significant sources of RF such as ac power lines and motors.

• CS616/CS625 probes enabled simultaneously and within approximately 9

inches of each other can cause erratic measurements. If probes must be close to each other, configure the enable lines to the datalogger control ports so that the probes are not enabled simultaneously.

3. Initial Inspection

• Upon receipt of the CS616/CS625, 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 expected product and cable length are received.

4. 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 period which is converted to volumetric water content using calibration equations. Datalogger instructions for period averaging can also be used.

CS616 and CS625 Water Content Reflectometers

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.

The water content reflectometer consists of two stainless steel rods connected to a printed circuit board. A shielded four-conductor cable is connected to the circuit board to supply power, enable the probe, and monitor the pulse output. The circuit board is encapsulated in epoxy.

High-speed electronic components on the circuit board are configured as a bistable multivibrator. The output of the multivibrator is connected to the probe rods which act as a wave guide. The travel time of the signal on the probe rods depends on the dielectric permittivity of the material surrounding the rods and the dielectric permittivity depends on the water content. Therefore, the oscillation frequency of the multivibrator is dependent on the water content of the media being measured. Digital circuitry scales the multivibrator output to an appropriate frequency for measurement with a datalogger. The water content reflectometer output is essentially a square wave. The probe output period ranges from about 14 microseconds with rods in air to about 42 microseconds with the rods completely immersed in typical tap water. A calibration equation converts period to volumetric water content.

The CS616/CS625's cable can terminate in:

5. Specifications

Features:

CS616 Compatibility Dataloggers: CR800 series

CR1000 CR3000 CR5000 CR510 CR10X CR23X

• 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.

• High accuracy and high precision

• Fast response time

• Designed for long-term unattended water content monitoring

• Probe rods can be inserted from the surface or buried at any

orientation to the surface

CS625 Compatibility Dataloggers: CR200X series

CR200 series

Probe-to-Probe Variability: ±0.5% VWC in dry soil, ±1.5% VWC in

Resolution: better than 0.1% volumetric water content

Water Content Accuracy: ±2.5% VWC using standard calibration with

Precision: better than 0.1% volumetric water content

5.1 Dimensions

Rods: 300 mm (11.8 in) long, 3.2 mm (0.13 in)

Probe Head: 85 x 63 x 18 mm (3.3 x 2.5 x 0.7 in)

CS616 and CS625 Water Content Reflectometers

typical saturated soil

bulk electrical conductivity ≤0.5 deciSiemen

-1

(dS m-1) and bulk density ≤1.55 g cm

meter

-3

in measurement range 0% VWC to 50% VWC

diameter, 32 mm (1.3 in) spacing

5.2 Weight

Probe (without cable): 280 g (9.9 oz)

Cable: 35 g m

5.3 Electrical Specifications

Output CS616: ±0.7 volt square wave with frequency

CS625: 0 to 3.3 volt square wave with frequency

Power: 65 mA @ 12 Vdc when enabled, 45 µA

Power Supply Requirements: 5 Vdc minimum, 18 Vdc maximum

Enable Voltage: 4 Vdc minimum, 18 Vdc maximum

Maximum Cable Length: 305 m (1000 ft)

Electromagnetic Compatibility: The CS616/CS625 is Œ compliant with

–1

(0.38 oz per ft)

dependent on water content

quiescent

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 CS616/CS625 meets EN61326 requirements for protection against electrostatic discharge and surge.

CS616 and CS625 Water Content Reflectometers

5.4 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 the soils used to characterize accuracy.

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. The precision of the CS616/CS625 is better than 0.1 % volumetric water content.

Soil Properties

The water content reflectometer operation can be affected when the signal applied to the probe rods is attenuated. The probe will provide a well-behaved response to changing water content, even in attenuating soils or other media, but the response may be different than described by the standard calibration. Consequently, a unique calibration is required. Change in probe response can occur when soil bulk electrical conductivity is greater than 0.5 dS m major contributor to soil electrical conductivity is the presence of free ions in solution from dissolution of soil salts. Soil organic matter and some clays can also attenuate the signal.

-1

. The

6. Installation

6.1 Orientation

6.2 Potential Problems with Improper Insertion

The probe rods can be inserted vertically into the soil surface or buried at any orientation to the surface. A probe inserted vertically into a soil surface will give an indication of the water content in the upper 30 cm of soil. The probe can be installed horizontal to the surface to detect the passing of wetting fronts or other vertical water fluxes. A probe installed at an angle of 30 degrees with the surface will give an indication of the water content of the upper 15 cm of soil.

The method used for probe installation can affect the accuracy of the measurement. The probe rods should be kept as close to parallel as possible when installed to maintain the design wave guide geometry. The sensitivity of this measurement is greater in the regions closest to the rod surface than at distances away from the surface. Probes inserted in a manner which generates air voids around the rods will reduce the measurement accuracy. In most soils, the soil structure will recover from the disturbance during probe insertion.

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.

6.3 Wiring

TABLE 6-1. CS616/625 wiring code.

NOTE

power Red

CS616 and CS625 Water Content Reflectometers

color function datalogger connection

red +12 V +12 V

green output SE analog channel

orange enable control port

black signal ground G

clear shield (power ground) G

Both the black ground wire and the clear shield wire must be connected to datalogger ground.

output gnd Black

output Green

enable Orange

drain/power gnd Clear

FIGURE 6-1. CS616 Water Content Reflectometer

gnd Black

output Green

enable Orange

drain/gnd Clear

FIGURE 6-2. CS625 Water Content Reflectometer

CS616 and CS625 Water Content Reflectometers

NOTE

6.4 Datalogger Instructions and Programming

This section is for users who write their own programs. A datalogger program can be generated using 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. The CRBasic instruction CS616() is used by the CR800, CR850, CR1000, CR3000, and CR5000 dataloggers to measure the CS616 output period. Edlog Instruction 138 is specifically designed for the CR510, CR10X, and CR23X to measure the output period of the CS616. The period value is used in the calibration for water content. The period in air is approximately 14.7 microseconds, and the period in saturated soil with porosity

0.4 is approximately 31 microseconds. Edlog Instruction 27, Period Average, can also be used to measure CS616 output period.

The output of the CS625 is a square wave with amplitude of 0 to 3.3 Vdc and a frequency that is dependent on the dielectric constant of the material surrounding the probe rods. The CRBasic instruction PeriodAvg() is used by the CR200(X) series dataloggers to measure the CS625 output period. The period value is used in the calibration for water content. The period in air is approximately 14.7 microseconds, and the period in saturated soil with porosity

0.4 is approximately 31 microseconds.

6.4.1 Measuring the CS616 Using CRBasic

The CRBasic instruction CS616() is used by the CR800, CR850, CR1000 CR3000, and CR5000 dataloggers to measure the CS616 output period (in microseconds). The CS616() instruction is used to enable and measure a CS616 Water Content Reflectometer.

CS616(Dest, Reps, SEChan, Port, MeasPerPort, Mult, Offset)

Dest: The Dest parameter is the variable or variable array in which to store the results of the measurement. Dest must be dimensioned to at least the number of Reps.

Reps: The Reps parameter is the number of measurements that should be made using this instruction. If Reps is greater than 1, Dest must be an array dimensioned to the size of Reps.

SEChan: The SEChan parameter is the number of the single-ended channel on which to make the first measurement. If the Reps parameter is greater than 1, the additional measurements will be made on sequential channels.

Port: The Port parameter is the control port that will be used to enable the CS616 sensor.

Code Description

Program Example 1

#1,2,3,4_Orange

#1,2,3,4_Blk & Clear

GND

1 Control Port 1 2 Control Port 2 3 Control Port 3 4 Control Port 4 5 Control Port 5 6 Control Port 6 7 Control Port 7 8 Control Port 8

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. MeasPerPort = 2 will result in one port being used for the first two measurements, and the next port being used for the next two measurements.

Mult, Offset: The Mult and Offset parameters are each a constant, variable, array, or expression by which to scale the results of the measurement.

6.4.1.1 CS616 Sample CRBasic Program 1

The following CR1000 program uses the CS616() instruction to measure eight CS616 probes connected to the CR1000 datalogger. Although this example is for the CR1000, other CRBasic dataloggers are programmed similarly.

CS616 and CS625 Water Content Reflectometers

Wiring for CRBasic

CS616 CR1000

CS616#1_Green 5H

CS616#2_Green 5L

CS616#3_Green 6H

CS616#4_Green 6L

#1,2,3,4_Red 12 V

CS616#5_Green 7H

CS616#6_Green 7L

CS616#7_Green 8H

CS616#8_Green 8L

#5,6,7,8_Orange C8

#5,6,7,8_Blk & Clear GND

#5,6,7,8_Red 12 V

Note: All CS616 “12V_Red” wires connected to CR1000 12 V terminal (user supplied common tie post may be required).

CS616 and CS625 Water Content Reflectometers

CR1000 Program Example 1

'Declare Public and Dim Variables Public batt_volt Public Panel_temp Public Period (8) Public VWC (8) Public Flag (1) Dim I

'Declare Constants 'CS616 Default Calibration Constants const a0= -0.0663 const a1= -0.0063 const a2= 0.0007 'Flag logic constants const high = true const low = false

'Define Data Tables DataTable (Dat30min,1,-1) DataInterval (0,30,Min,10) Minimum (1,batt_volt,IEEE4,0,False) Average (1,Panel_temp,IEEE4,0) Sample (8,Period(),FP2) Sample (8,VWC(),FP2) EndTable

'Main Program BeginProg Scan (5,Sec,0,0) 'scan instructions every 5 sec Battery (Batt_volt) PanelTemp (Panel_temp,250) ' '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 8ea CS616 probes on CR1000 CS616 (Period(1),4,9,7,4,1.0,0) 'measure 4ea CS616 probes, enable w/ C7 CS616 (Period(5),4,13,8,4,1.0,0) 'measure 4ea CS616 probes, enable w/ C8 ' For I=1 to 8 'convert CS616 period to Volumetric Water Content VWC(I)=a0 + al*Period(I) + a2*Period(I)^2 Next ' flag(1)= low 'set Flag 1 = Low ' EndIf '+++++++++++++++++++++++++++++++ ' CallTable Dat30min 'Call Output Tables NextScan 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

CR1000 AM16/32-series (4x16) CS616*

CS616 and CS625 Water Content Reflectometers

'Declare Public and Dim Variables Public batt_volt Public Panel_temp Public Period (48) Public VWC (48) Public Flag (1) Dim I

'Declare Constants 'CS616 Default Calibration Constants const a0= -0.0663 const a1= -0.0063 const a2= 0.0007 'Flag logic constants const high = true const low = false

'Define Data Tables DataTable (Dat30min,1,-1) DataInterval (0,30,Min,10) Minimum (1,batt_volt,FP2,0,False) Average (1,Panel_temp,FP2,0) Sample (48,Period(),FP2) Sample (48,VWC(),FP2) EndTable

Control/Common

Sensor

Terminals

C4 RES Odd H CS616#1_Green

C5 CLK Odd L CS616#2_Green

12 V 12 V Gnd #1,2,3_Blk & Clear

Gnd Gnd Even H CS616#3_Green

1H COM Odd H Even L #1,2,3_Orange

1L COM Odd L

Gnd Gnd

2H COM Even H

C6 COM Even L

*Three sensors to each set of AM16/32 terminals.

CR1000 Program Example 2

+ 35 hidden pages

Campbell Scientific CS616, CS625 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Warranty

Assistance

Table of Contents

1. Introduction

2. Cautionary Statements

3. Initial Inspection

4. Overview

5. Specifications

5.1 Dimensions

5.2 Weight

5.3 Electrical Specifications

5.4 Operational Details

6. Installation

6.1 Orientation

6.2 Potential Problems with Improper Insertion

6.3 Wiring

6.4 Datalogger Instructions and Programming

6.4.1 Measuring the CS616 Using CRBasic

6.4.1.1 CS616 Sample CRBasic Program 1

6.4.1.2 CS616 Sample CRBasic Program 2