223 Delmhorst Cylindrical Soil Moisture Block Revision: 5/13 C o p y r i g h t © 1 9 9 1 - 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 .
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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.......
Table of Contents 7-4. 7-5. Polynomial Coefficients for Converting Sensor Resistance to Bars.. 13 Polynomial Error – 10 Bar Range .....................................................
223 Delmhorst Cylindrical Soil Moisture Block 1. Introduction The 223 is a gypsum block that determines soil water potential by measuring electrical resistance. When the 223 is wet, electrical resistance is low. As the 223 dries, resistance increases. This gypsum block connects to a datalogger via an AM16/32-series, AM32, or AM416 multiplexer. The 223 gypsum soil moisture block is configured for use with multiplexers. The –L option on the model 223-L indicates that the cable length is user specified.
223 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.
223 Delmhorst Cylindrical Soil Moisture Block 2. NOTE Select the Datalogger Model and enter the Scan Interval, and then select Next. A scan rate of 30 seconds or longer is recommended when using a multiplexer. 3. Under Devices, select AM16/32, and select the right arrow (in center of screen) to add it to the list.
223 Delmhorst Cylindrical Soil Moisture Block 4 4. Select 223 Soil Moisture Sensor, and select the right arrow (in center of screen) to add it to the list of sensors to be measured. The Properties window will appear after the right arrow is selected. 5. In the Properties window, enter the number of sensors, the Resistance units, and the Soil Water Potential units. After entering the information, click OK, and then select Next.
223 Delmhorst Cylindrical Soil Moisture Block 6. 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. 9. Click on Wiring Diagram and select the CR1000 tab. Wire the CR1000 to the AM16/32 according to the wiring diagram generated by SCWin Short Cut.
223 Delmhorst Cylindrical Soil Moisture Block 10. Select the AM16/32 tab and wire the 223 sensors to the AM16/32 according to the wiring diagram generated by SCWin Short Cut. 5. Overview The 223 gypsum soil moisture block is configured for use with multiplexers. The –L option on the model 223–L indicates that the cable length is user specified. This manual refers to the sensor as the 223.
223 Delmhorst Cylindrical Soil Moisture Block 6. Specifications Features: • Compatible with multiplexers allowing measurement of multiple sensors • Multiplexer connection prevents electrolysis from prematurely destroying the soil moisture block • 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 CR10(X) 21X CR23X Diameter: ~2.25 cm (0.
223 Delmhorst Cylindrical Soil Moisture Block 7. Operation CAUTION 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 223 is shown in FIGURE 7-1 and TABLE 7-1.
223 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 Diagram, if using Short Cut. Dataloggers that use CRBasic include our CR800, CR850, CR1000, CR3000, and CR5000. Dataloggers that use Edlog include our CR10(X), 21X, CR23X, and CR7. CRBasic and Edlog are included with LoggerNet, PC400, and RTDAQ software.
223 Delmhorst Cylindrical Soil Moisture Block 7.2.1.2 Edlog The generalized Edlog programming sequence follows: ACTIVATE MULTIPLEXER/RESET INDEX For the CR10(X) and CR23X, use Edlog instruction Do (P86) to set the port high. For the 21X and CR7, use Edlog instruction Set Port(s) (P20) to set the port high. BEGIN MEASUREMENT LOOP Use Edlog instruction Beginning of Loop (P87) CLOCK PULSE AND DELAY With the CR23X and CR10(X) the clock line is connected to a control port.
223 Delmhorst Cylindrical Soil Moisture Block The output from the BrHalf instruction or Instruction 5 is the ratio of signal voltage to excitation voltage: Vs/Vx = Rs/(Rs + R1) where, Vs = Signal Voltage Vx = Excitation Voltage Rs = Sensor Resistance R1 = Fixed Bridge Resistor. 7.2.3 Calculate Sensor Resistance The sensor resistance is calculated using an expression in CRBasic or Edlog instruction BR Transform Rf[X/(1–X)] (P59).
223 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.
223 Delmhorst Cylindrical Soil Moisture Block Typical Values from TABLE 7-3 Block Resistance (kohms) 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. (R1) C0 C1 C2 C3 C4 C5 0.1–10 0.1 0.15836 6.1445 –8.4189 9.2493 –3.1685 0.33392 TABLE 7-5. Polynomial Error – 10 Bar Range BARS Vs/Vx Rs (kohms × 0.
223 Delmhorst Cylindrical Soil Moisture Block 7.2.5 Example Programs 7.2.5.1 Example CR1000 Program Below is a CR1000 program that measures five 223 sensors, calculates resistance, and calculates soil water potential. FIGURE 7-3.
223 Delmhorst Cylindrical Soil Moisture Block 'Define Data Tables DataTable(Table1,True,–1) DataInterval(0,60,Min,10) Sample(1,kohms(1),FP2) Sample(1,WP_kPa(1),FP2) Sample(1,kohms(2),FP2) Sample(1,WP_kPa(2),FP2) Sample(1,kohms(3),FP2) Sample(1,WP_kPa(3),FP2) Sample(1,kohms(4),FP2) Sample(1,WP_kPa(4),FP2) Sample(1,kohms(5),FP2) Sample(1,WP_kPa(5),FP2) EndTable DataTable(Table2,True,–1) DataInterval(0,1440,Min,10) Minimum(1,BattV,FP2,False,False) EndTable 'Main Program BeginProg 'Main Scan Scan(30,Sec,1,0) '
3 Delmhorst Cylindrical Soil Moisture Block 7.2.5.2 Example CR10(X) Program Multiplexer CR10(X) FIGURE 7-4. Wiring for CR10(X) example *Table 1 Program 01: 60.0000 Execution Interval (seconds) 01: Do (P86) 1: 41 Set Port 1 High ;Enable multiplexer 02: Beginning of Loop (P87) 1: 0 Delay 2: 16 Loop Count ;Start of measurement loop 03: Do (P86) 1: 72 ;Clock Multiplexer to next channel Pulse Port 2 04: Step Loop Index (P90) 1: 2 Step 05: AC Half Bridge (P5) 1: 2 2: 14 3: 1 4: 2 5: 250 6: 1-7: 1.
223 Delmhorst Cylindrical Soil Moisture Block 08: Do (P86) 1: 51 ;Turn off multiplexer Set Port 1 Low ;The following loop checks each block resistance and calculates ;water potential if BlockR < 17 kohms. Because 2 blocks are measured ;with each pass through the previous measurement loop, it is simpler ;to use a separate loop for the calculations. ;Leave out following loop if only recording block resistance.
223 Delmhorst Cylindrical Soil Moisture Block 19: Real Time (P77) 1: 220 ;Output Day and Hour/Minute Day,Hour/Minute (midnight = 2400) 20: Sample (P70) 1: 64 2: 1 Reps Loc [ BlockR_1 ] ;Output resistances and Water Potentials 7.2.5.3 Example 21X Program Multiplexer 21X FIGURE 7-5.
223 Delmhorst Cylindrical Soil Moisture Block 05: AC Half Bridge (P5) 1: 2 2: 14 3: 1 4: 2 5: 500 6: 1-7: 1.0 8: 0.0 ;Measure the 2 connected 223 blocks Reps 500 mV Fast Range SE Channel Excite all reps w/Exchan 2 mV Excitation Loc [ BlockR_1 ] ; -- >>> advance location by index Mult Offset 06: BR Transform Rf[X/(1–X)] (P59) 1: 2 Reps 2: 1-Loc [ BlockR_1 ] 3: 1.
223 Delmhorst Cylindrical Soil Moisture Block 14: Z=F (P30) 1: –99999 2: 33-- F Z Loc [ WatPo_1 ] 15: End (P95) ;End then do 16: End (P95) ;End loop 17: If time is (P92) 1: 2: 3: 0 60 10 ;Output Resistance and Water Potential each Hour Minutes (Seconds --) into a Interval (same units as above) Set Output Flag High (Flag 0) 18: Set Active Storage Area (P80) 1: 1 Final Storage Area 1 2: 60 Array ID 20 ;Fix the Array ID to 60 19: Real Time (P77) 1: 220 ;Output Day and Hour/Minute Day,Hour/Minute
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