Operator’s Manual
Decagon Devices, Inc.
Version: February 29, 2016 — 11:10:55
Page 1: ...Operator s Manual Decagon Devices Inc Version February 29 2016 11 10 55 ...
Page 2: ...WA 99163 Phone 509 332 5600 Fax 509 332 5158 Website www decagon com Email support decagon com or sales decagon com Trademarks ECH2O is a registered trademark of Decagon Devices Inc All Rights Reserved c 2007 2014 Decagon Devices Inc All Rights Reserved ii ...
Page 3: ...gger Requirements 6 3 3 Adapter Cable Wiring 6 3 4 Extending the Sensor Leads 7 3 5 UV Protection 7 4 Interpreting Data 8 4 1 Understanding Data from the Em50 9 4 1 1 Processed Data File 9 4 1 2 Unprocessed Data File 10 4 1 3 DataTrac3 File 11 4 2 Understanding Data from Other Data Loggers 11 5 LWS Theory 12 5 1 How the LWS Works 12 5 2 How the LWS Mimics a Real Leaf 12 6 Appendix A Sample CSI Pro...
Page 4: ...ack Decagon has Customer Service Representatives available to speak with you Monday through Friday between 7 am and 5 pm Pacific time Note If you purchased your sensor through a distributor please con tact them for assistance Email support decagon com or sales decagon com Phone 509 332 5600 Fax 509 332 5158 If contacting us by email or fax please include as part of your mes sage your instrument se...
Page 5: ...oard the factory where originally manufactured Material and equipment covered hereby which is not manufactured by Seller shall be covered only by the warranty of its manufacturer Seller shall not be liable to Buyer for loss damage or injuries to persons including death or to property or things of whatsoever kind including but not without limitation loss of anticipated profits occasioned by or aris...
Page 6: ...e sensor surface Water on the sensor surface does not need to bridge electrical traces to be detected as is common with resistance based surface wetness sensors This means that the LWS does not need to be painted before use which eliminates the need for individual sensor calibration 2 1 Specifications Measurement Time 10 ms Power 2 5 VDC 2 mA to 5 VDC 7 mA Output 320 to 1000 mV 3 V excitation Oper...
Page 7: ...2 ABOUT THE LEAF WETNESS SENSOR LWS Figure 1 The Leaf Wetness Sensor 4 ...
Page 8: ...WS is designed to be deployed either in the canopy or on weather station masts There are two holes in the non sensing por tion of the sensor body for mounting The holes can be used with either zip ties or with 4 40 bolts Figure 2 Top View of Installed LWS in Plant Canopy 5 ...
Page 9: ...ion and read a volt level signal with 12 bit or better resolution should be compatible with the LWS The current requirement at 2 5 V is around 2 mA and a 5 V it is 7 to 8 mA Note The LWS is intended only for use with data loggers and readout devices which can provide short excitation pulses leaving the probes turned off most of the time Continuous excitation not only wastes battery power but may u...
Page 10: ...e junction and shrinking appropriately sized heat shrink tubing over the still wet silicone sealant 3 5 UV Protection The LWS leaf wetness sensor is designed to withstand typical out door radiation and precipitation loads for greater than two years If you are using the LWS in areas with non typical unusually high ra diation loads we recommend additional applications of McNett UV Tech available fro...
Page 11: ...logger the LWS outputs 445 raw counts when dry When the sensor is totally wet as in a heavy rain the signal can range up to around 1400 counts Varying amounts of water on the surface of the sensor cause a sensor output proportional to the amount of water on the sensor s surface Figure 4 Sample raw output from the LWS Because ice has a much lower dielectric constant than that of liquid water the se...
Page 12: ...le format is selected three columns of data are output for each LWS port Column 1 The number of minutes that the LWS output was over 450 raw counts in the preceding wake interval So if you shoose a 30 minute wake interval then the number can range from 0 the sensor was never wet during the 30 minute period to 30 the sensor was always wet during that 30 minute period Take the sum of these numbers i...
Page 13: ...reading every wake interval typically 30 minutes or more instead of the one minute wetness resolution available in column 1 and 2 Note that the conversion from Em50 raw counts to mV with 3 000 mV excitation is mV raw counts 0 733 4 1 2 Unprocessed Data File When an unprocessed Excel file format is downloaded three columns of data are output for each LWS port Column 1 The cumulative number of minut...
Page 14: ...nderstanding Data from Other Data Loggers With non Em50 data loggers the user needs to establish a wetness threshold for their system The dry output of the LWS varies with excitation voltage note that the acceptable excitation voltage range is 2 5 to 5 V The LWS dry output is easily determined from time series data such as those presented in Figure 4 A wetness threshold should be chosen that is sl...
Page 15: ...f the leaf is 1 425 J m 2 K 1 This is closely approximated by the thin 0 65 mm fiberglass construction of the LWS which has a heat capacity of 1 480 J m 2 K 1 By mimicking the thermody namic properties of a real leaf the LWS more closely matches the wetness state of the canopy The sensor has also been engineered to closely match the radiative properties of real leaves Healthy leaves generally abso...
Page 16: ...airs or less waxy cuticles It is impossible for any sensor to accurately mimic the properties of all leaves The LWS is engineered to be repeatable among units so that re lationships can be determined between the wetness state of the sen sor and the wetness state of various agricultural or natural plant canopies Painting and individual sensor calibration is not necessary with the LWS 13 ...
Page 17: ...had sensor output in the preceding ranges Note that the wetness thresholds depend on excitation applied If you are exciting with other than 3000 mV you will need to determine a custom wetness threshold Table 1 Program 01 1 Execution Interval seconds 1 Excite Delay SE P4 1 1 Reps 2 20 Auto 60 Hz Reject Slow Range OS 1 06 3 1 SE Channel 4 1 Excite all reps w Exchan 1 5 1 Delay 0 01 sec units 6 3000 ...
Page 18: ... Histogram P75 15793 1 1 Reps 2 3 No of Bins 3 0 Open Form 4 1 Bin Select Value Loc LWS_mV 5 0 Frequency Distribution 6 330 Low Limit 7 337 High Limit Table 2 Programs 02 0 0000 Execution Interval seconds Table 3 Subroutines End Program 15 ...
Page 19: ...opkins Ct Pullman WA 99163 USA Model Number LWS 1 Year of First Manufacture 2006 This is to certify that the Dielectric Leaf Wetness Sensor manufactured by Decagon Devices Inc a corporation based in Pullman Washington USA meets or exceeds the standards for CE compliance as per the Council Directives noted above All instruments are built at the factory at Decagon and pertinent testing documentation...
Page 20: ...ements 6 Sample CSI program 14 Wiring Configuration 6 DataTrac3 11 Files 11 Dielectric Measurement 12 ECH2O Utility 9 Processed Data File or tab delim ited text file 9 Unprocessed Data File 10 Email 1 Fax 1 Installation 5 LWS Operation 5 Thermal Properties 12 Seller s Liability 2 Specifications 3 Theory of Operation 12 UV Protection 7 Warranty 2 17 ...
