227 Delmhorst Cylindrical Soil Moisture Block Revision: 5/13 C o p y r i g h t © 1 9 8 3 - 2 0 1 3 C a m p b e l l S c i e n t i f i c , I n c .
Warranty “PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified in the corresponding Campbell pricelist or product manual. Products not manufactured, but that are re-sold by Campbell, are warranted only to the limits extended by the original manufacturer.
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Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Introduction .................................................................1 2. Cautionary Statements...............................................1 3. Initial Inspection .........................................................1 4. Quickstart ....................................................................2 4.1 4.2 Installation.......
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227 Delmhorst Cylindrical Soil Moisture Block 1. Introduction The 227 is a gypsum block that determines soil water potential by measuring electrical resistance. When the 227 is wet, electrical resistance is low. As the 227 dries, resistance increases. This gypsum block connects directly to a datalogger. The –L option on the model 227-L indicates that the cable length is user specified. This manual refers to the sensor as the 227. Before using the 227, please study • • • 2. 3.
227 Delmhorst Cylindrical Soil Moisture Block 4. Quickstart Please review Section 7, Operation, for wiring, CRBasic programming, and Edlog programming. 4.1 4.2 Installation 1. Soak blocks in water for one hour then allow them to dry. 2. Repeat Step 1. 3. Make sensor access holes to the depth required. 4. Soak the blocks for two to three minutes. 5. Mix a slurry of soil and water to a creamy consistency and place one or two tablespoons into the sensor access hole. 6.
227 Delmhorst Cylindrical Soil Moisture Block 2. Select the Datalogger Model and enter the Scan Interval, and then select Next. 3. Select 227 Soil Moisture Block under Meteorological | Soil Moisture, and select the right arrow (in center of screen) to add it to the list of sensors to be measured.
227 Delmhorst Cylindrical Soil Moisture Block 4 4. Enter the Resistance units and the Soil Water Potential units. After entering the information, click on OK, and then select Next. 5. Choose the Outputs and then select Finish. 7. In the Save As window, enter an appropriate file name and select Save. 8. In the Confirm window, click Yes to download the program to the datalogger.
227 Delmhorst Cylindrical Soil Moisture Block 9. 5. Click on Wiring Diagram and wire the 227 to the CR1000 according to the wiring diagram generated by SCWin Short Cut. Overview The 227 gypsum soil moisture block connects directly with a Campbell Scientific datalogger; it is not compatible with our CR200(X)-series. The –L option on the Model 227-L indicates that the cable length is user specified. This manual refers to the sensor as the 227.
227 Delmhorst Cylindrical Soil Moisture Block 6. Specifications Features: 6 • Contains blocking capacitors in its cable that minimizes galvanic degradation and measurement errors due to ground loops • Measures a wide range of matric potential • Buffers salts in soil • No maintenance required • Compatible with most Campbell Scientific dataloggers Compatible Dataloggers: CR800 CR850 CR1000 CR3000 CR5000 CR7 CR9000(X) CR500 CR510 CR10(X) 21X CR23X Diameter: ~2.25 cm (0.88 in) Length: ~2.
227 Delmhorst Cylindrical Soil Moisture Block 7. Operation NOTE 7.1 The black outer jacket of the cable is Santoprene® rubber. This compound was chosen for its resistance to temperature extremes, moisture, and UV degradation. However, this jacket will support combustion in air. It is rated as slow burning when tested according to U.L. 94 H.B. and will pass FMVSS302. Local fire codes may preclude its use inside buildings. Wiring The 227 schematic is shown in FIGURE 7-1.
227 Delmhorst Cylindrical Soil Moisture Block 7.2 Programming NOTE This section describes using CRBasic or Edlog to program the datalogger. See Section 4.2, Use SCWin to Program Datalogger and Generate Wiring Program, if using SCWin. The datalogger is programmed using either CRBasic or Edlog. Dataloggers that use CRBasic include our CR800, CR850, CR1000, CR3000, CR5000, and CR9000(X). Dataloggers that use Edlog include our CR500, CR510, CR10(X), 21X, CR23X, and CR7.
227 Delmhorst Cylindrical Soil Moisture Block TABLE 7-2. Excitation and Voltage Ranges NOTE Datalogger mV Excitation Full Scale Range CR800/CR850 250 ±250 mV CR1000 250 ±250 mV CR3000 200 ±200 mV CR5000 200 ±200 mV CR9000(X) 200 ±200 mV 21X 500 ±500 mV CR7 500 ±500 mV CR500/CR510 250 ±250 mV CR10(X) 250 ±250 mV CR23X 200 ±200 mV Do not use a slow integration time as sensor polarization errors will occur. 7.2.
227 Delmhorst Cylindrical Soil Moisture Block TABLE 7-3. Typical Soil Water Potential, Rs and Vs / Vx BARS Rs (kohms) Vs/Vx 0.1 0.060 0.0566 0.2 0.130 0.1150 0.3 0.260 0.2063 0.4 0.370 0.2701 0.5 0.540 0.3506 0.6 0.750 0.4286 0.7 0.860 0.4624 0.8 1.100 0.5238 0.9 1.400 0.5833 1.0 1.700 0.6296 1.5 3.400 0.7727 1.8 4.000 0.8000 2.0 5.000 0.8333 3.0 7.200 0.8780 6.0 12.500 0.9259 10.0 17.000 0.9444 11.0 22.200 0.9569 12.0 22.400 0.9573 13.0 30.000 0.
Soil Water Potential (-Bars) 227 Delmhorst Cylindrical Soil Moisture Block 18 16 14 12 10 8 6 4 2 0 TypicalValues Values from Table Typical from TABLE 7-3 2 0.1 to 10 Bar Polynomial Fit 0 5 10 15 20 25 35 30 Block Resistance Resistance (kohms) (kOhms) Block FIGURE 7-2. Polynomial fit to typical block resistance vs. water potential TABLE 7-4. Polynomial Coefficients for Converting Sensor Resistance to Bars BARS = C0 + C1(Rs) +C2(Rs)2+C3(Rs)3+C4(Rs)4+C5(Rs)5 BARS MULT.
227 Delmhorst Cylindrical Soil Moisture Block TABLE 7-5. Polynomial Error - 10 Bar Range BARS Vs / Vx Rs (kohms × 0.1) BARS COMPUTED ERROR 0.1 0.0566 0.006 0.1949 0.0949 0.2 0.115 0.013 0.2368 0.0368 0.3 0.2063 0.026 0.3126 0.0126 0.4 0.2701 0.037 0.3746 –0.0254 0.5 0.3506 0.054 0.4670 –0.0330 0.6 0.4286 0.075 0.5756 –0.0244 0.7 0.4624 0.086 0.6302 –0.0698 0.8 0.5238 0.11 0.7442 –0.0558 0.9 0.5833 0.14 0.8778 –0.0222 1.0 0.6296 0.17 1.0025 0.0025 1.
227 Delmhorst Cylindrical Soil Moisture Block 'CR1000 'Declare Variables and Units Public Batt_Volt Public Rs_kOhm Public WP_kPa Units Batt_Volt=Volts Units Rs_kOhm=kOhms Units WP_kPa=kPa 'Define Data Tables DataTable(Table1,True,-1) DataInterval(0,60,Min,10) Sample(1,Rs_kOhm,FP2) EndTable DataTable(Table2,True,-1) DataInterval(0,1440,Min,10) Minimum(1,Batt_Volt,FP2,False,False) EndTable 'Main Program BeginProg Scan(5,Sec,1,0) 'Default Datalogger Battery Voltage measurement Batt_Volt: Battery(Batt_Volt) '2
227 Delmhorst Cylindrical Soil Moisture Block TABLE 7-7. Wiring for CR10X Example Program Color Function CR10(X) Black Excitation E1 Red Signal SE1 White Signal Ground AG Clear Shield G *Table 1 Program 01: 10.
227 Delmhorst Cylindrical Soil Moisture Block 07: Z=F (P30) 1: -99999 2: 0 3: 2 F Exponent of 10 Z Loc [ WatPoten ] 08: End (P95) ;End then do 09: If time is (P92) 1: 0 Minutes (Seconds --) into a 2: 360 Interval (same units as above) 3: 10 Set Output Flag High ;Output every six hours 10: Real Time (P77) ;Output time 1: 220 Day,Hour/Minute (midnight = 2400) 11: 1: 2: Sample (P70) 2 Reps 1 Loc [ Rs ;Output Rs and Water potential ] 15
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