Campbell Scientific CS616 and CS625 Water Content Reflectometers - Manual (Page 12)

CS616 and CS625 Water Content Reflectometers
6.4 Datalogger Instructions and Programming
This section is for users who write their own programs. A
datalogger program can be generated using Short Cut software.
You do not need to read this section if using Short Cut.
The output of the CS616 is a square wave with amplitude of ±0.7 Vdc and a
frequency that is dependent on the dielectric constant of the material
surrounding the probe rods. The CRBasic instruction CS616() is used by the
CR800, CR850, CR1000, CR3000, and CR5000 dataloggers to measure the
CS616 output period. Edlog Instruction 138 is specifically designed for the
CR510, CR10X, and CR23X to measure the output period of the CS616. The
period value is used in the calibration for water content. The period in air is
approximately 14.7 microseconds, and the period in saturated soil with porosity
0.4 is approximately 31 microseconds. Edlog Instruction 27, Period Average,
can also be used to measure CS616 output period.
The output of the CS625 is a square wave with amplitude of 0 to 3.3 Vdc and a
frequency that is dependent on the dielectric constant of the material
surrounding the probe rods. The CRBasic instruction PeriodAvg() is used by
the CR200(X) series dataloggers to measure the CS625 output period. The
period value is used in the calibration for water content. The period in air is
approximately 14.7 microseconds, and the period in saturated soil with porosity
0.4 is approximately 31 microseconds.
6.4.1 Measuring the CS616 Using CRBasic
The CRBasic instruction CS616() is used by the CR800, CR850, CR1000
CR3000, and CR5000 dataloggers to measure the CS616 output period (in
microseconds). The CS616() instruction is used to enable and measure a
CS616 Water Content Reflectometer.
CS616(Dest, Reps, SEChan, Port, MeasPerPort, Mult, Offset)
Dest : The Dest parameter is the variable or variable array in which to store the
results of the measurement. Dest must be dimensioned to at least the number of
Reps.
Reps : The Reps parameter is the number of measurements that should be made
using this instruction. If Reps is greater than 1, Dest must be an array
dimensioned to the size of Reps.
SEChan : The SEChan parameter is the number of the single-ended channel on
which to make the first measurement. If the Reps parameter is greater than 1,
the additional measurements will be made on sequential channels.
Port : The Port parameter is the control port that will be used to enable the
CS616 sensor.
NOTE
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