Campbell Scientific 223-L User Manual

223 Delmhorst Cylindrical

Soil Moisture Block

Revision: 5/13

Copyright © 1991-2013

Campbell Scientific, Inc.

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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 Installation............................................................................................2

4.2 Use SCWin to Program Datalogger and Generate Wiring Diagram ....2

5. Overview......................................................................6

6. Specifications .............................................................7

7. Operation.....................................................................8

7.1 Wiring ..................................................................................................8

7.2 Programming........................................................................................9

7.2.1 Control the Multiplexer.................................................................9

7.2.1.1 CRBasic..............................................................................9

7.2.1.2 Edlog ................................................................................10

7.2.2 Excite and Measure the 223........................................................10

7.2.3 Calculate Sensor Resistance........................................................11

7.2.4 Calculate Soil Water Potential ....................................................11

7.2.5 Example Programs ......................................................................14

7.2.5.1 Example CR1000 Program...............................................14

7.2.5.2 Example CR10(X) Program .............................................16

7.2.5.3 Example 21X Program.....................................................18

Figures

7-1. 223 wiring ............................................................................................8

7-2. Polynomial fit to typical block resistance vs. water potential ............13

7-3. Wiring for CR1000 example..............................................................14

7-4. Wiring for CR10(X) example ............................................................16

7-5. Wiring for example 21X program......................................................18

Tables

7-1. 223 Wiring ...........................................................................................8

7-2. Excitation and Voltage Ranges ..........................................................10

7-3. Typical Soil Water Potential, Rs and Vs / Vx......................................12

i

Table of Contents

7-4. Polynomial Coefficients for Converting Sensor Resistance to Bars.. 13

7-5. Polynomial Error – 10 Bar Range ..................................................... 13

ii

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. This manual refers to the sensor as the 223.

Before using the 223, please study

• Section 2, Cautionary Statements

• Section 3, Initial Inspection

• Section 4, Quickstart

2. Cautionary Statements

• The black outer jacket of the cable is Santoprene

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.

• Avoid installing in depressions where water will puddle after a rain storm.

• Don’t place the 223 in high spots or near changes in slope unless wanting

to measure the variability created by such differences.

• To maximize longevity, remove the gypsum blocks during the winter.

3. Initial Inspection

• Upon receipt of the 223, inspect the packaging and contents for damage.

File damage claims with the shipping company.

• The model number and cable length are printed on a label at the

connection end of the cable. Check this information against the shipping
documents to ensure the correct product and cable length are received.

®

rubber. This jacket will

1

223 Delmhorst Cylindrical Soil Moisture Block

4. Quickstart

Please review Section 7, Operation, for wiring, CRBasic programming, and
Edlog programming.

4.1 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. Place the blocks in the hole and force the slurry to envelope it. This will

insure uniform soil contact.

7. Back fill the hole, tamping lightly at frequent intervals.

4.2 Use SCWin to Program Datalogger and Generate Wiring Diagram

The simplest method for programming the datalogger to measure the 223 is to
use Campbell Scientific’s SCWin Short Cut Program Generator.

1. Open Short Cut and click on New Program.

2

223 Delmhorst Cylindrical Soil Moisture Block

2. Select the Datalogger Model and enter the Scan Interval, and then select
Next.

NOTE

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.

3

223 Delmhorst Cylindrical Soil Moisture Block

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.

4

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.

5

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.

The Delmhorst cylindrical block is composed of gypsum cast around two
concentric electrodes which confine current flow to the interior of the block,
greatly reducing potential ground loops. Gypsum located between the outer
electrode and the soil creates a buffer against salts which may affect the
electrical conductivity. Individual calibrations are required for accurate
readings of soil water potential.

The multiplexer that the 223 is connected to leaves the circuit open when no
measurements are being made. This blocks direct current flow from the 223 to
datalogger ground and prevents electrolysis from prematurely destroying the
sensor.

The 223 should not be connected directly to the datalogger. The 227
Delmhorst soil moisture block is available for direct connection and has
capacitors in the cable that block direct current flow.

Gypsum blocks typically last for one to two years. Saline or acidic soils tend
to degrade the block, reducing longevity. To maximize longevity, gypsum
blocks not used during the winter should be removed from the field. Shallow
blocks may become frozen and crack, while blocks located below the frost line
may not maintain full contact with the soil. Regardless of depth, blocks left in
the field over winter are subject to the corrosive chemistry of the soil.

6

6. Specifications

Features:

Compatible Dataloggers: CR800

CR850
CR1000
CR3000
CR5000
CR7
CR10(X)
21X
CR23X

223 Delmhorst Cylindrical Soil Moisture Block

• 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

Diameter: ~2.25 cm (0.88 in)

Length: ~2.86 cm (1.25 in)

Material: Gypsum

Electrode Configuration: Concentric cylinders
Center electrode: Excitation
Outer electrode: Ground

Calibration: Measurements are affected by soil salinity,

including fertilizer salts. Individual
calibrations are required for accurate
measurement of soil water potential. The soil
water potential versus resistance values in
TABLE 7-3 are “typical” values supplied by
Delmhorst Corporation. Neither Delmhorst
nor Campbell Scientific make any claim as to
the accuracy of these values. The calibration
equations in Section 7.2.4, Calculate Soil
Water Potential, were fit to the values in
TABLE 7-3 to allow output of an estimated
water potential.

7

223 Delmhorst Cylindrical Soil Moisture Block

7. Operation

CAUTION

7.1 Wiring

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.

The 223 is shown in FIGURE 7-1 and TABLE 7-1. The leads from the block
electrodes are connected directly to the H and L inputs on the AM16/32-series,
AM32, or AM416 multiplexer. The lead from the center electrode (white
stripe or solid white) connects to H and the lead from the outer electrode
(black) to L. A 1k resistor at the datalogger is used to complete the half bridge
measurement.

Black with
White Stripe
(or White) to H

Black
to L

FIGURE 7-1. 223 wiring

TABLE 7-1. 223 Wiring

Color Function Multiplexer

Black w/ White Stripe or White Excitation H

Black Signal Ground L

8

7.2 Programming

223 Delmhorst Cylindrical Soil Moisture Block

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.

The datalogger program needs to control the multiplexer, measure the sensor,
calculate the sensor resistance, and convert the resistance to potential in bars.
Example programs are provided in Section 7.2.5, Example Programs.

7.2.1 Control the Multiplexer

When a multiplexer is used, the measurements are placed within a loop. Each
pass through the loop, the multiplexer is clocked to the next channel and the
sensors connected to that channel are measured. The programming sequence
for using the multiplexer is shown in Section 7.2.1.1, CRBasic, and Section

7.2.1.2, Edlog. For more information, see the multiplexer manual.

7.2.1.1 CRBasic

The generalized CRBasic programming sequence follows:

ACTIVATE MULTIPLEXER/RESET INDEX
Portset (1 ,1) 'Set C1 high to Enable Multiplexer
I=0
BEGIN MEASUREMENT LOOP
SubScan (0,sec,16) 'This example measures 16 sets
CLOCK PULSE AND DELAY
Portset (2,1) ‘Set port 2 high
Delay (0,20,mSec)
Portset (2,0) ‘Set port 2 low
INCREMENT INDEX AND MEASURE
I=I+1

‘223 measurement instruction
‘Storing results in Variable(I)

END MEASUREMENT LOOP
NextSubScan

DEACTIVATE MULTIPLEXER
Portset (1 ,0) 'Set C1 Low to disable Multiplexer

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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. Instruction Do (P86) with the pulse port command

(71 – 78) pulses the clock line high for 10 ms. Instruction Excitation

with Delay (P22) can be added following the Do (P86) to delay an

additional 10 ms.
MEASURE SENSOR AND CALCULATE RESISTANCE
See Section 7.2.2, Excite and Measure the 223, and Section 7.2.3,

Calculate Sensor Resistance.
END MEASUREMENT LOOP
Use Edlog instruction End (P95).
DEACTIVATE MULTIPLEXER
For the CR10(X) and CR23X, use Edlog instruction Do (P86) to set

the port low. For the 21X and CR7, use Edlog instruction Set Port(s)

(P20) to set the port low.

7.2.2 Excite and Measure the 223

The sensor is excited and measured using the BrHalf instruction in CRBasic or
Instruction 5 (AC Half Bridge) in Edlog. Recommended excitation voltages

and input ranges are given in TABLE 7-2. TABLE 7-2 shows the excitation
and voltage ranges used with our dataloggers.

TABLE 7-2. Excitation and Voltage Ranges

Datalogger mV Excitation Full Scale Range

CR800/CR850 250 ±250 mV

CR1000 250 ±250 mV

CR3000 200 ±200 mV

CR5000 200 ±200 mV

21X 500 ±500 mV

CR7 500 ±500 mV

CR10(X) 250 ±250 mV

CR23X 200 ±200 mV

10

223 Delmhorst Cylindrical Soil Moisture Block

The output from the BrHalf instruction or Instruction 5 is the ratio of signal
voltage to excitation voltage:

V

where, V
V
R
R

= Rs/(Rs + R1)

s/Vx

= Signal Voltage

s

= Excitation Voltage

x

= Sensor Resistance

s

= Fixed Bridge Resistor.

1

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). The expression or Edlog
instruction BR Transform Rf[X/(1–X)] (P59) takes the Half Bridge output

) and computes sensor resistance as follows:

(V

s/Vx

R

= R1(X/(1 – X))

s

where, X = V

s/Vx

The bridge transform multiplier would normally be 1000, representing the
fixed resistor (R

). A bridge multiplier of 1000 produces values of Rs larger

1

than 6999 ohms causing the datalogger to overrange when using low
resolution. To avoid overranging, a bridge multiplier of 1 should be used to
output sensor resistance (R

7.2.4 Calculate Soil Water Potential

) in terms of kohms.

s

The datalogger program can be written to store block resistance or can
calculate water potential from a block calibration. The soil water potential
versus resistance values in TABLE 7-3 are typical values supplied by
Delmhorst Corporation.

11

223 Delmhorst Cylindrical Soil Moisture Block

TABLE 7-3. Typical Soil Water Potential,

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

and Vs / Vx

R

s

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 0.9677

14.0 32.500 0.9701

15.0 35.000 0.9722

For the typical resistance values listed in TABLE 7-3, soil water potential
(bars) is calculated from sensor resistance (R

) using the 5th order polynomial

s

(FIGURE 7-2 and TABLE 7-4). TABLE 7-5 shows the polynomial error. The
nonlinear relationship of R

to bars rules out averaging Rs directly.

s

The polynomial is entered as an expression in CRBasic or by using Edlog
instruction Polynomial (P55). The polynomial to calculate soil water potential
is fit to the 0.1 to 10 bar range using a least square fit. TABLE 7-4 lists the
coefficients and equation for the 0.1 to 10 bar polynomial.

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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 C

C

1

C

2

C

3

C

4

5

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 V

s/Vx

R

s

(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

1.5 0.7727 0.34 1.5970 0.0970

1.8 0.8000 0.40 1.7834 –0.0166

2 0.8333 0.50 2.0945 0.0945

3 0.8780 0.72 2.8834 –0.1166

6 0.9259 1.25 6.0329 0.0329

10 0.9444 1.70 9.9928 –0.0072

ERROR (BARS) = TABLE 7-3 VALUES – COMPUTED VALUES

13

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.

'CR1000

'Declare Variables and Units
Dim LCount
Public BattV
Public PTemp_C
Public kohms(5)
Public WP_kPa(5)

Units BattV=Volts
Units PTemp_C=Deg C
Units kohms=kilohms
Units WP_kPa=kPa

14

FIGURE 7-3. Wiring for CR1000 example

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)
'Default Datalogger Battery Voltage measurement 'BattV'
Battery(BattV)
'Default Wiring Panel Temperature measurement 'PTemp_C'
PanelTemp(PTemp_C,_60Hz)
'Turn AM16/32 Multiplexer On
PortSet(2,1)
Delay(0,150,mSec)
LCount=1
SubScan(0,uSec,5)
'Switch to next AM16/32 Multiplexer channel
PulsePort(1,10000)
'223 Soil Moisture Sensor measurements 'kohms()' and 'WP_kPa()' on the AM16/32 Multiplexer
BrHalf(kohms(LCount),1,mV250,1,1,1,250,True,20000,250,1,0)
'Convert resistance ratios to kilohms and kilohms to water potential
kohms(LCount)=kohms(LCount)/(1–kohms(LCount))
If kohms(LCount)<17 Then
WP_kPa(LCount)=kohms(LCount)*0.1

WP_kPa(LCount)=0.15836+(6.1445*WP_kPa(LCount))+(–8.4189*WP_kPa(LCount)^2)+(9.2493*WP_kPa(LCount)^3)+(–3.1685*WP_kPa(LCount)^4)+(0.33392*WP_kPa(LCount)^5)

WP_kPa(LCount)=WP_kPa(LCount)*100
Else
WP_kPa(LCount)=1000
EndIf
LCount=LCount+1
NextSubScan
'Turn AM16/32 Multiplexer Off
PortSet(2,0)
Delay(0,150,mSec)
'Call Data Tables and Store Data
CallTable(Table1)
CallTable(Table2)
NextScan
EndProg

15

223 Delmhorst Cylindrical Soil Moisture Block

7.2.5.2 Example CR10(X) Program

CR10(X)

Multiplexer

FIGURE 7-4. Wiring for CR10(X) example

*Table 1 Program
01: 60.0000 Execution Interval (seconds)

01: Do (P86) ;Enable multiplexer
1: 41 Set Port 1 High

02: Beginning of Loop (P87) ;Start of measurement loop
1: 0 Delay
2: 16 Loop Count

03: Do (P86) ;Clock Multiplexer to next channel
1: 72 Pulse Port 2

04: Step Loop Index (P90) ;Step index by 2 each pass through loop
1: 2 Step

05: AC Half Bridge (P5) ;Measure the 2 connected 223 blocks
1: 2 Reps
2: 14 250 mV Fast Range
3: 1 SE Channel
4: 2 Excite all reps w/Exchan 2
5: 250 mV Excitation
6: 1-- Loc [ BlockR_1 ] ;-- >>> advance location by index
7: 1.0 Mult
8: 0.0 Offset

06: BR Transform Rf[X/(1–X)] (P59) ;Calculate resistance from Vs/Vx
1: 2 Reps
2: 1-- Loc [ BlockR_1 ]
3: 1 Multiplier (Rf)

07: End (P95)

16

223 Delmhorst Cylindrical Soil Moisture Block

08: Do (P86) ;Turn off multiplexer
1: 51 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.

09: Beginning of Loop (P87) ;Loop to calculate water potential
1: 0 Delay
2: 32 Loop Count

10: If (X<=>F) (P89) ;If Rs < 17, apply polynomial
1: 1-- X Loc [ BlockR_1 ]
2: 4 <
3: 17 F
4: 30 Then Do

11: Z=X*F (P37) ;Scale Rs for polynomial
1: 1-- X Loc [ BlockR_1 ]
2: .1 F
3: 33-- Z Loc [ WatPot_1 ]

12: Polynomial (P55) ;Convert Rs to bars with 10 bar polynomial
1: 1 Reps
2: 33-- X Loc [ WatPot_1 ]
3: 33-- F(X) Loc [ WatPot_1 ]
4: .15836 C0
5: 6.1445 C1
6: –8.4198 C2
7: 9.2493 C3
8: –3.1685 C4
9: .33392 C5

13: Else (P94) ;If Rs > 17 load over range value for potential

14: Z=F (P30)
1: –99999 F
2: 0 Exponent of 10
3: 33 Z Loc [ WatPot_1 ]

15: End (P95) ;End then do

16: End (P95) ;End loop

17: If time is (P92) ;Output Resistance and Water Potential each

Hour

1: 0 Minutes (Seconds --) into a
2: 60 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)

18: Set Active Storage Area (P80) ;Fix the Array ID to 60
1: 1 Final Storage Area 1
2: 60 Array ID

17

223 Delmhorst Cylindrical Soil Moisture Block

19: Real Time (P77) ;Output Day and Hour/Minute
1: 220 Day,Hour/Minute (midnight = 2400)

20: Sample (P70) ;Output resistances and Water Potentials
1: 64 Reps
2: 1 Loc [ BlockR_1 ]

7.2.5.3 Example 21X Program

21X

FIGURE 7-5. Wiring for example 21X program

*Table 1 Program
01: 10 Execution Interval (seconds)

01: Set Port (P20) ;Enable multiplexer
1: 1 Set High
2: 1 Port Number

02: Beginning of Loop (P87) ;Start of measurement loop
1: 0 Delay
2: 16 Loop Count

03: Excitation with Delay (P22) ;Clock Multiplexer to next channel
1: 1 Ex Channel
2: 1 Delay w/Ex (units = 0.01 sec)
3: 1 Delay After Ex (units = 0.01 sec)
4: 5000 mV Excitation

04: Step Loop Index (P90) ;Step index by 2 each pass through loop
1: 2 Step

Multiplexer

18

223 Delmhorst Cylindrical Soil Moisture Block

05: AC Half Bridge (P5) ;Measure the 2 connected 223 blocks
1: 2 Reps
2: 14 500 mV Fast Range
3: 1 SE Channel
4: 2 Excite all reps w/Exchan 2
5: 500 mV Excitation
6: 1-- Loc [ BlockR_1 ] ; -- >>> advance location by index
7: 1.0 Mult
8: 0.0 Offset

06: BR Transform Rf[X/(1–X)] (P59) ;Calculate resistance from Vs/Vx
1: 2 Reps
2: 1-- Loc [ BlockR_1 ]
3: 1.0 Mult (Rf)

07: End (P95)

08: Set Port (P20) ;Turn off AM416
1: 0 Set Low
2: 1 Port Number

;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.

09: Beginning of Loop (P87) ;Loop to calculate water potential
1: 0 Delay
2: 32 Loop Count

10: If (X<=>F) (P89) ;If Rs < 17, apply polynomial
1: 1-- X Loc [ BlockR_1 ]
2: 4 <
3: 17 F
4: 30 Then Do

11: Z=X*F (P37) ;Scale Rs for polynomial
1: 1-- X Loc [ BlockR_1 ]
2: .1 F
3: 33-- Z Loc [ WatPo_1 ]

12: Polynomial (P55) ;Convert Rs to bars with 10 bar polynomial
1: 1 Reps
2: 33-- X Loc [ WatPo_1 ]
3: 33-- F(X) Loc [ WatPo_1 ]
4: .15836 C0
5: 6.1445 C1
6: –8.4198 C2
7: 9.2493 C3
8: –3.1685 C4
9: .33392 C5

13: Else (P94) ;If Rs > 17 load overrange value for potential

19

223 Delmhorst Cylindrical Soil Moisture Block

14: Z=F (P30)
1: –99999 F
2: 33-- Z Loc [ WatPo_1 ]

15: End (P95) ;End then do

16: End (P95) ;End loop

17: If time is (P92) ;Output Resistance and Water Potential each

1: 0 Minutes (Seconds --) into a
2: 60 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)

18: Set Active Storage Area (P80) ;Fix the Array ID to 60
1: 1 Final Storage Area 1
2: 60 Array ID

19: Real Time (P77) ;Output Day and Hour/Minute
1: 220 Day,Hour/Minute (midnight = 2400)

20: Sample (P70) ;Output resistances and Water Potentials
1: 64 Reps ;32 reps if not outputting water potential
2: 1 Loc [ BlockR_1 ]

Hour

20

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