Campbell Scientific 227-L Delmhorst Cylindrical Soil Moisture Block - Manual (Page 5)

Table of Contents
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1. Introduction.................................................................1
2. Cautionary Statements...............................................1
3. Initial Inspection .........................................................1
4. Quickstart ....................................................................2
4.1 Installation............................................................................................2
4.2 Use SCWin to Program Datalogger and Generate Wiring Diagram ....2
5. Overview......................................................................5
6. Specifications .............................................................6
7. Operation.....................................................................7
7.1 Wiring ....................................................................................................7
7.2 Programming..........................................................................................8
7.2.1 Excite and Measure the 227 .........................................................8
7.2.2 Calculate Sensor Resistance.........................................................8
7.2.3 Calculate Soil Water Potential......................................................9
7.2.4 Programming Examples .............................................................12
7.2.4.1 Example CR1000 Program...............................................12
7.2.4.2 Example CR10(X) Program .............................................13
Figures
7-1. 227 schematic.......................................................................................7
7-2. Polynomial fit to typical block resistance vs. water potential ............11
Tables
7-1. 227 Wiring ...........................................................................................7
7-2. Excitation and Voltage Ranges ............................................................9
7-3. Typical Soil Water Potential, R
s
and V
s
/ V
x
......................................10
7-4. Polynomial Coefficients for Converting Sensor Resistance to Bars ..11
7-5. Polynomial Error - 10 Bar Range.......................................................12
7-6. Wiring for CR1000 Example Program...............................................12
7-7. Wiring for CR10X Example Program................................................14
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