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Decagon GS3 Operator's Manual

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Operator's Manual
Decagon Devices, Inc.
Version: December 1, 2014 — 11:53:59

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  • Page 1 Operator’s Manual Decagon Devices, Inc. Version: December 1, 2014 — 11:53:59...
  • Page 2 Decagon Devices, Inc. 2365 NE Hopkins Court Pullman WA 99163 Phone: 509-332-5600 Fax: 509-332-5158 Website: www.decagon.com Email: support@decagon.com or sales@decagon.com Trademarks c 2011-2014 Decagon Devices, Inc. All Rights Reserved...

  • Page 3: Table Of Contents

    4.2 3.5mm Stereo Plug Wiring ....10 4.3 Connecting to a Non-Decagon Logger ..11 5 Communication 5.1 Serial Communication .

  • Page 4: Introduction

    Customer Support If you ever need assistance with your GS3, or if you just have ques- tions or feedback, there are several ways to contact us. Customer ser- vice representatives are available to speak with you Monday through Friday, between 7am and 5pm Pacific time.

  • Page 5: Specifications

    1 INTRODUCTION Specifications Volumetric Water Content Accuracy: (unitless) from 1 to 40 (soil range), 15% from 40 to 80: Using a generic calibration: 0.03 ( 3% VWC) typical in mineral soils that have solution electrical conductivity dS/m Using medium specific calibration, 0.01 to 0.02 1 to 2% VWC) in any porous medium...

  • Page 6: Warranty

    Cable Length: 5 m standard; custom cable length available upon request Warranty The GS3 has a one year warranty on parts and labor. The warranty activates when the instrument arrives at your location. Seller’s Liability Seller warrants new equipment of its own manufacture against defec-...
  • Page 7 1 INTRODUCTION the implied warranties of merchantability and fitness for a particular purpose), not expressly set forth herein.

  • Page 8: Theory

    Temperature The GS3 uses a small thermistor to take temperature readings. It is located underneath the sensor overmold, next to one of the prongs so it remains in thermal equilibrium with the medium, and reads the temperature of the prong surface.

  • Page 9: Converting Bulk Ec To Pore Ec

    However, some special applications in highly saline substrates may require measurements with bulk EC greater than the specified range. The GS3 will measure up to 23 dS/m bulk EC, but user calibration is required above 10 dS/m. Additionally, EC measurements above 10 dS/m are very sensitive to contamination of the electrodes by skin oils, etc.

  • Page 10: Pore Water Vs. Solution Ec

    = 80 3 0 37 ( soil where T is the soil temperature ( C) measured by the GS3. soil Finally, is an offset term loosely representing the dielectric per- σb=0 mittivity of the dry soil. Hilhorst (2000) recommended that σb=0...

  • Page 11: Reference

    2 THEORY water until the soil saturates, then the soil is placed on filter paper in a vacuum funnel and suction is applied. An electrical conductivity measurement on the water removed from the sample will give the solution electrical conductivity. Theoretically, the two are related by the bulk density.

  • Page 12: Calibration

    Calibration Dielectric Permittivity In some specific cases, a calibration that gives dielectric permittivity (combined real and imaginary) for the GS3 is useful. The dielectric of the medium, is the standard factory calibrated output of the GS3 before applying a calibration.

  • Page 13: Connecting Sensors

    To update your software to the latest versions, please visit Decagon’s support site at http://www.decagon.com/support/. To use the GS3 with your Em50 data logger, simply plug the stereo plug into one of the five ports on the data logger and use either ECH2O Utility, or DataTrac 3 software (see respective manuals) to configure that port for the GS3 and set the measurement interval.

  • Page 14: Connecting To A Non-Decagon Logger

    Figure 2: Pigtail Wiring GS3 sensors with the stripped and tinned cable option can be made with custom cable lengths (up to 1000 ft) on a per-foot fee basis. This option gets around the need for splicing wire (a possible failure point).
  • Page 15 Figure 3: Wiring Diagram NOTE: The acceptable range of excitation voltages is from 3.6 to 15 VDC. If you wish to read the GS3 with the Campbell Scientific Data. Loggers, you need to power the sensors off of the 12 V port (switched if you use TTL serial).

  • Page 16: Communication

    Integrators guide, which gives more detailed explanations and instructions. Serial Communication The GS3 communicates in both serial and SDI-12. In some applica- tions where non-Decagon data loggers are used, SDI-12 will be the best choice. When excitation voltage is applied, the GS3 makes a measurement.
  • Page 17 The SDI-12 protocol requires that all sensors have a unique address. GS3 sensors come from the factory with an SDI-12 address of 0. To add more than one SDI-12 sensor to a system, the sensor address must change.

  • Page 18: Sensor Bus

    5 COMMUNICATION Reading the GS3 sensor in SDI-12 mode using a CSI data logger re- quires a function call. An example program from Edlog and CRBasic can be found in the software section of http://www.decagon.com/sup port/. The dielectric permittivity ( ) is the first number output by the sensor, the second number is temperature in C, and the third is the electrical conductivity in S/cm.

  • Page 19: Power

    Most data loggers will run this sequence without any user input, but occasionally it is necessary to interrogate the sensor directly. A full list of the SDI-12 commands implemented in the GS3 is available by contacting Decagon. Additional examples of SDI-12 programs can be found at our software...

  • Page 20: Campbell Scientific Programs

    5 COMMUNICATION Campbell Scientific Programs The GS3 is a SDI-12 compatible sensor. This makes programming for the sensor in CRBasic or Edlog straightforward. Simply choose the SDI-12 Recorder command and input the necessary parameters. As mentioned earlier, the sensor outputs three values, so be sure to define your array size as 3 in CRBasic (i.e.

  • Page 21: Installing The Sensors

    6 INSTALLING THE SENSORS Installing the Sensors You can insert the GS3 sensor into soilless substrates in a variety of ways; however, the orientation of the sensor does affect the sensor accuracy. In addition, high spatial variability in soilless substrates will drastically affect the difference between sensor readings from one...

  • Page 22: Removing The Sensors

    Rootball Removing the Sensors The GS3 is easily removed from substrates. The stainless steel nee- dles slip easily in and out of all types of growing media. Still, we recommend the sensors never be pulled out by their cables, as this can put immense strain on the wires inside.
  • Page 23 6 INSTALLING THE SENSORS Note: Be sure not to touch the prongs with an un-gloved hand or contact them with any source of oil or other non-conducting residue.

  • Page 24: Troubleshooting

    7 TROUBLESHOOTING Troubleshooting Table 1: Troubleshooting Quick Guide If this problem occurs: Refer to: Sensor not responding Problem #1 Sensor reading too low Problem #2 Sensor reading too high Problem #3 1. PROBLEM: Sensor not responding. SOLUTION: Check power to the sensor Check sensor cable and 3.5 mm plug integrity Check data logger wiring to ensure White is 12 V supply, Red is digital out, and Bare is ground.
  • Page 25 7 TROUBLESHOOTING Check to make sure that the media was not packed excessively dur- ing sensor installation. Higher density can cause sensor reading to be elevated. Ensure the calibration equation you are using is appropriate for your media type. There are significant differences between substrate calibrations so be sure to use the one specific to your substrate.

  • Page 26: Declaration Of Conformity

    Model Number: Year of First Manufacture: 2011 This is to certify that the GS3 greenhouse 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 is freely available for verification.
  • Page 27 Dielectric Permittivity, 5, 7 Electrical Conductivity, 5 Email, 1 Fax, ii, 1 Installation Orientation, 18 Removal, 19 Loggers CSI, 17 Non-Decagon, 11 Phone, ii, 1 Pore Water EC, 7 Power Requirements, 2 Seller’s Liability, 3 Sensor Accuracy, 2 Range, 2 Resolution, 2 Specifications, 2...

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