Campbell LWS Instruction Manual
  1. Manuals
  2. Brands
  3. Campbell Manuals
  4. Accessories
  5. LWS
  6. Instruction manual

Campbell LWS Instruction Manual

Dielectric leaf wetness sensor
Hide thumbs Also See for LWS:
Table of Contents

Advertisement

Quick Links

Download this manual
LWS Dielectric
Leaf Wetness Sensor
Revision: 2/15
C o p y r i g h t
©
2 0 0 8 - 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 .

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the LWS and is the answer not in the manual?

Questions and answers

Related Manuals for Campbell LWS

Summary of Contents for Campbell LWS

  • Page 1 LWS Dielectric Leaf Wetness Sensor Revision: 2/15 C o p y r i g h t © 2 0 0 8 - 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

    B. Example Programs ..........B-1 Example CR1000 Program .............. B-1 Example CR6 Program ..............B-2 Figures 7-1. LWS Dielectric Leaf Wetness Sensor ..........6 7-2. Top view of a typical LWS installation ..........6 7-3. Typical LWS response ................. 8...
  • Page 8 Table of Contents Tables B-1. CR1000 Example Wiring ..............B-1 B-2. CR6 Example Wiring ..............B-2...

  • Page 9: Introduction

    If damage to the cable is suspected, consult with a Campbell Scientific application engineer. • Although the LWS is rugged, it should be handled as a precision scientific instrument. • Over time, the accumulation of dust and bird droppings can cause the dry output to rise.

  • Page 10: Quickstart

    LWS Dielectric Leaf Wetness Sensor Quickstart Short Cut is an easy way to program your datalogger to measure the LWS and assign datalogger wiring terminals. The following procedure shows using Short Cut to program the LWS. 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...
  • Page 11 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 | Miscellaneous Sensors folder. Select LWS Dielectric Leaf Wetness Sensor. Click to move the selection to the Selected device window.

  • Page 12: Overview

    Overview Measurement The LWS measures the dielectric constant of a zone approximately 1 cm from the upper surface of the sensor. The dielectric constant of water (≈80) and ice (≈5) are much higher than that of air (≈1), so the measured dielectric constant is strongly dependent on the presence of moisture or frost on the sensor surfaces.

  • Page 13: Specifications

    –2 –1 . By mimicking the thermodynamic properties of a real leaf, the LWS closely matches the wetness state of the canopy. The sensor closely matches the radiative properties of real leaves. Healthy leaves generally absorb solar radiation in much of the visible portion of the spectrum, but selectively reject much of the energy in the near-infrared.

  • Page 14: Installation

    (p. 2) Field Installation The LWS is designed to be mounted on a small diameter rod. Deployment in a plant canopy or on a weather station mast is typical. Two holes in the sensor body are available for mounting with zip ties or 4-40 bolts (FIGURE FIGURE 7-2).

  • Page 15: Wiring

    7.3.1 Voltage Measurement The LWS requires excitation voltage between 2.5 and 5 Vdc. It produces an output voltage dependent on the dielectric constant of the medium surrounding the probe. Output voltage ranges from 10 to 50% of the excitation voltage.

  • Page 16: Interpreting Data

    LWS Dielectric Leaf Wetness Sensor The CR200(X) uses the ExDelSE() CRBasic instruction to measure the probe’s output. The ExDelSE() instruction and parameters are as follows: ExDelSE( Dest, Reps, SEChan, ExChan, ExmV, Delay, Mult, Offset ) 7.3.2 Interpreting Data Many leaf wetness applications, such as phytopathology, require a Boolean interpretation of leaf wetness data such as whether or not water is present.

  • Page 17: Maintenance

    Boolean threshold. Clean the sensing surface with a moist cloth periodically or when elevated dry output is detected. The LWS leaf wetness sensor is designed to withstand typical outdoor radiation and precipitation loads for greater than two years. If you are using...
  • Page 18 LWS Dielectric Leaf Wetness Sensor...

  • Page 19: Importing Short Cut Code Into A Program Editor

    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 or Edlog program editor.
  • Page 20 Appendix A. Importing Short Cut Code Into a Program Editor mark) begins each line. This character instructs the datalogger compiler to ignore the line when compiling the datalogger code.

  • Page 21: Example Programs

    DataInterval(0,60,Min,10) Sample(1,BattV,FP2) Sample(1,PTemp_C,FP2) Sample(1,LWmV,FP2) Totalize(1,LWMDry,FP2,False) Totalize(1,LWMCon,FP2,False) Totalize(1,LWMWet,FP2,False) EndTable DataTable(Table2,True,-1) DataInterval(0,1440,Min,10) Minimum(1,BattV,FP2,False,False) EndTable 'Main Program BeginProg 'Main Scan Scan(5,Sec,1,0) 'Default Datalogger Battery Voltage measurement 'BattV' Battery(BattV) 'Default Wiring Panel Temperature measurement 'PTemp_C' PanelTemp(PTemp_C,_60Hz) 'LWS Dielectric Leaf Wetness Sensor measurement 'LWmV' BrHalf(LWmV,1,mV2500,1,1,1,2500,False,10000,_60Hz,2500,0)

  • Page 22: Example Cr6 Program

    Appendix B. Example Programs 'Determine Minutes Dry, LWMDry, Minutes Wet or Contaminated, ‘LWMCon, and Minutes Wet, LWMWet for this Scan LWMDry=0 LWMCon=0 LWMWet=0 If LWmV<274 Then LWMDry=0.08333333 Else If LWmV>=284 Then LWMWet=0.08333333 Else LWMCon=0.08333333 EndIf EndIf 'Call Data Tables and Store Data CallTable(Table1) CallTable(Table2) NextScan...
  • Page 23 Scan(5,Sec,1,0) 'Default Datalogger Battery Voltage measurement 'BattV' Battery(BattV) 'Default Wiring Panel Temperature measurement 'PTemp_C' PanelTemp(PTemp_C,60) 'LWS Dielectric Leaf Wetness Sensor measurement 'LWmV' BrHalf(LWmV,1,mV5000,U2,U1,1,2500,False,10000,60,2500,0) 'Determine Minutes Dry 'LWMDry', Minutes Wet or Contaminated 'LWMCon', and Minutes Wet 'LWMWet' for this Scan LWMDry=0...
  • Page 24 Appendix B. Example Programs...
  • Page 26 • info@campbellsci.com.cn • info@campbellsci.de www.campbellsci.com www.campbellsci.de Campbell Scientific do Brasil Ltda. (CSB) Campbell Scientific Spain, S. L. (CSL Spain) Rua Apinagés, nbr. 2018 ─ Perdizes Avda. Pompeu Fabra 7-9, local 1 CEP: 01258-00 ─ São Paulo ─ SP 08024 Barcelona...

Table of Contents