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Campbell 253 Instruction Manual

Soil matric potential sensors
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253 and 257
Soil Matric Potential Sensors
Revision: 8/15
C o p y r i g h t
©
1 9 9 3 - 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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Summary of Contents for Campbell 253

  • Page 1 253 and 257 Soil Matric Potential Sensors Revision: 8/15 C o p y r i g h t © 1 9 9 3 - 2 0 1 5 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

    2. Cautionary Statements ..........1 3. Initial Inspection ............1 4. Quickstart ..............2 4.1.1 257 SCWin Programming ............. 2 4.1.2 253 SCWin Programming ............. 5 5. Overview ..............8 6. Specifications ............10 7. Operation ..............10 Installation/Removal ................10 Wiring ....................11 7.2.1...
  • Page 8 Table of Contents Figures 5-1. 257 Soil Matric Potential Sensor with capacitor circuit and completion resistor installed in cable. Model 253 is the same, except that it does not have completion circuitry in the cable..9 7-1. 257 schematic ..................12 7-2.

  • Page 9: Introduction

    Avoid installing in depressions where water will puddle after a rain storm. • Don’t place the 253 or 257 in high spots or near changes in slope unless • wanting to measure the variability created by such differences.

  • Page 10: Quickstart

    253 and 257 Soil Matric Potential Sensors Quickstart Short Cut is an easy way to program your datalogger to measure the 253 or 257 and assign datalogger wiring terminals. The following sections show using Short Cut to program the 253 and 257.
  • Page 11 253 and 257 Soil Matric Potential Sensors 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 folder, then select the Temperature sub-folder. Select 107 Temperature Probe.
  • Page 12 253 and 257 Soil Matric Potential Sensors 6. Under the Available Sensors and Devices list, select the Sensors | Meteorological | Soil Moisture | 257 Soil Moisture Sensor. Click move the selection to the Selected device window. Select the resistance units, soil water units, soil water potential range, and soil reference temperature.

  • Page 13: 253 Scwin Programming

    253 and 257 Soil Matric Potential Sensors 8. 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.
  • Page 14 253 and 257 Soil Matric Potential Sensors 4. Select the datalogger and enter the scan interval, and select Next. NOTE A scan rate of 30 seconds or longer is recommended when using a multiplexer. 5. Under the Available Sensors and Devices list, select the Sensors folder, then select the Temperature sub-folder.
  • Page 15 AM16/32. Click to move the selection to the Selected device window. 7. Under the Sensors list, select the Meteorological | Soil Moisture | 253 Soil Moisture Sensor. Click to move the selection to the Selected device window. Select the number of sensors, resistance units, soil water...

  • Page 16: Overview

    Campbell Scientific multiplexers and the 257 is the Watermark 200 Soil Matric Potential Block modified for use with Campbell Scientific dataloggers. The –L option on the Model 257-L and 253-L indicates that the cable length is user specified. This manual refers to the sensors as the 257 and 253. The typical cable length for the 257 is 25 ft.

  • Page 17: Completion Resistor Installed In Cable. Model 253 Is The Same

    253 to be shorter. The cable length of each 253 only needs to cover the distance from the multiplexer to the point of measurement. Typical cable length for the 253 is 25 to 50 ft.

  • Page 18: Specifications

    • The 257 contains blocking capacitors in its cable that minimizes • galvanic degradation and measurement errors due to ground loops For the 253, the multiplexer connection prevents electrolysis from • prematurely destroying the probe • Compatible with Campbell Scientific CRBasic Dataloggers: CR6,...

  • Page 19: Wiring

    253 and 257 Soil Matric Potential Sensors 5. Insert the sensors in the sensor access hole. A length of 1/2 inch class 315 PVC pipe fits snugly over the sensor collar and can be used to push in the sensor. The PVC can be left in place with the wires threaded through the pipe and the open end taped shut (duct tape is adequate).

  • Page 20: 253 Wiring

    TABLE and FIGURE show the datalogger-to-multiplexer connections for the 2 x 32 mode. Appendix B.2, 253 Program Example , shows (p. B-3) wiring for the 4 x 16 mode.

  • Page 21: Datalogger To Am16/32-Series Multiplexer Wiring (2 X 32 Mode)

    253 and 257 Soil Matric Potential Sensors TABLE 7-3. Datalogger to AM16/32-series Multiplexer Wiring (2 x 32 Mode) Datalogger Connection Multiplexer Connection Terminal Terminal C (control port) C (control port) U configured for voltage excitation , EX, VX (voltage excitation) 1000 Ω...

  • Page 22: Programming

    7.3.1 BRHalf Instruction CRBasic dataloggers use the BRHalf() instruction with the RevEx argument set to True to excite and measure the 253 and 257. The result of the BRHalf() instruction is the ratio of the measured voltage divided by the excitation voltage.

  • Page 23: Resistance Calculation

    253 and 257 Soil Matric Potential Sensors 7.3.2 Resistance Calculation The CRBasic program should include an expression that calculates resistance. If the result of the BRHalf() instruction is assigned to a variable called kOhms, then use the following expression to calculate resistance:...

  • Page 24: Non-Linear Relationship

    253 and 257 Soil Matric Potential Sensors 7.3.3.2 Non-Linear Relationship For more precise work, calibration and temperature compensation in the range of 10 to 100 kPa has been refined by Thompson and Armstrong (1987), as defined in the non-linear equation, 01306 .

  • Page 25: Soil Water Matric Potential In Other Units

    Desired Unit Multiply Result By 0.001 0.01 Interpreting Results As a general guide, 253 and 257 measurements indicate soil matric potential as follows: 0 to –10 kPa = Saturated soil –10 to –20 kPa = Soil is adequately wet (except coarse sands, which are beginning to lose water).

  • Page 26: Reference

    253 and 257 Soil Matric Potential Sensors 2. Sensor is not in an active portion of the root system, or the irrigation is not reaching the sensor area. This can happen if the sensor is sitting on top of a rock or below a hard pan which may impede water movement. Re- installing the sensor usually solves this problem.

  • Page 27: Importing Short Cut Code

    Appendix A. Importing Short Cut Code 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.

  • Page 29: Example Programs

    Appendix B. Example Programs These examples show programs written for the CR1000 and the CR6 dataloggers. With minor changes to excitation and voltage ranges, the code in the CR1000 examples will work with all compatible CRBasic dataloggers (see TABLE 7-4). B.1 257 Program Examples The following examples demonstrate the programming used to measure the resistance (kΩ) of one 257 sensor with the datalogger.

  • Page 30: Cr6 Program Measuring A 107 And 257

    253-L and 257-L Soil Matric Potential Sensors B.1.1 CR6 Program Measuring a 107 and 257 'CR6 Public T107_C, kOhms, WP_kPa Units T107_C=Deg C Units kOhms=kOhms Units WP_kPa=kPa DataTable(Hourly,True,-1) DataInterval(0,60,Min,10) Average(1,T107_C,FP2,False) Sample(1,WP_kPa,FP2) EndTable BeginProg Scan(1,Sec,1,0) '107 Temperature Sensor measurement T107_C: Therm107(T107_C,1,U2,U1,0,60,1,0)

  • Page 31: 253 Program Example

    107 temperature probes and five 253 sensors on an AM16/32-series multiplexer (4x16 mode) with the CR1000 datalogger. In this example, a 107 temperature probe is buried at the same depth as a corresponding 253 sensor. The linear equation is used and the non-linear equation is included in the program notes.
  • Page 32 253-L and 257-L Soil Matric Potential Sensors ‘CR1000 Public T107_C(5), WP_kPa(5), kOhms(5) Units T107_C()=Deg C Units kOhms=kOhms Units WP_kPa=kPa DataTable(Hourly,true,-1) DataInterval(0,60,Min,10) Average(5, T107_C, FP2, 0) Sample(5, WP_kPa, FP2) Sample(5, kOhms, FP2) EndTable BeginProg Scan(60,Sec, 3, 0) PortSet(1,1) 'Turn AM16/32 Multiplexer On...
  • Page 34 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...

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