CS615 WATER CONTENT REFLECTOMETER
8
6: Do (P86) ;disable CS615
1:
55
Set Port 5 Low
7: Z=1/X (P42) ;convert kHz to milliseconds
1:
1
X Loc [ 615kHz ]
2:
2
Z Loc [ 615msec ]
8: Polynomial (P55) ;convert period to water content
1:
1
Reps
2:
2
X Loc [ 615msec ]
3:
3
F(X) Loc [ 615water ]
4:
-0.187
C0
5:
0.037
C1
6:
0.335
C2
7:
0.0
C3
8:
0.0
C4
9:
0.0
C5
9: Do (P86)
1:
10
Set Output Flag High
10: Real Time (P77)
1:
0220
Day,Hour/Minute
11: Sample (P70)
1:
2
Reps
2:
2
Loc [615msec]
9: Do (P86)
1:
21
Set Flag 1 low
12: End (P95)
End Program
10.3 SAMPLE PROGRAM 3
Program using the Pulse Count Instruction (P3)
of 21X datalogger and AM416 multiplexer to
read 48 CS615 probes.
See the cautions listed
below
.
This program is written to read 48 CS615s
every hour and write the water content value to
output storage. The AM416 multiplexer is a 16
channel multiplexer with 4 lines per channel.
See figure 3 for wiring schematic. Three CS615
outputs and a common enable for all 3 probes
are attached to each AM416 channel. Three
CS615s connected to a AM416 channel are
enabled simultaneously while the Pulse Count
Instruction uses a repetition value of 3 to
sequentially read the probe outputs. The
frequency value of the Pulse Count Instruction
is converted to period by the Z=1/X Instruction
(P42) and the calibration to volumetric water
content is invoked using the Polynomial
Instruction. The water content values are
written to output storage.
Attention to program structure when using the
Pulse Count Instruction with sensors that are
periodically enabled is necessary to ensure
accurate results. See Section 7.2 for a detailed
description of the Pulse Count Instruction.
CAUTION:
1.
The probe rods of the CS615 are
essentially antennae which transmit and
receive radio waves. Interference can
occur when enabled probes are in close
proximity and electrical conductivity of
the measured medium is high.
Generally, interference is not a problem
when the distance between enabled
probes is greater than 20 cm. It may be
necessary to configure probe
placement and multiplexer connection
to alleviate probe interaction.
2.
Reading 48 CS615s using the Pulse
Count Instruction will take
approximately 32 seconds. This may
conflict with other measurements.
;{21X}
;
*Table 1 Program
01:
1.0
Execution Interval (seconds)
1: If time is (P92) ;take CS615 readings hourly
1:
0000
Minutes into a
2:
60
Minute Interval
3:
30
Then Do
2: Do (P86) ;enable AM416
1:
41
Set Port 1 High
3: Do (P86) ;set CS615 enable high
1:
43
Set Port 3 High
4: Beginning of Loop (P87) ;multiplexing loop
1:
0000
Delay
2:
16
Loop Count
;loop index of 3 so 3 readings measured
;by pulse instruction are advanced 3
;locations each pass through measurement
loop.
5: Step Loop Index (P90)
1:
3
Step
6: Do (P86) ;clock AM416
1:
72
Pulse Port 2
