CS616 and CS625 Water Content Reflectometers
4
6.
After selecting the sensor, click at the left of the screen on
Wiring
Diagram
to see how the sensor is to be wired to the datalogger. The
wiring diagram can be printed out now or after more sensors are
added.
7.
Select any other sensors you have, then finish the remaining
Short Cut
steps to complete the program. The remaining steps are outlined in
Short Cut
Help
, which is accessed by clicking on
Help | Contents |
Programming Steps
.
8.
If
LoggerNet
,
PC400
,
RTDAQ
, or
PC200W
is running on your PC, and
the PC to datalogger connection is active, you can click
Finish
in
Short Cut
and you will be prompted to send the program just created
to the datalogger.
9.
If the sensor is connected to the datalogger, as shown in the wiring
diagram in step 6, check the output of the sensor in the datalogger
support software data display to make sure it is making reasonable
measurements.
5.
Overview
The water content reflectometer consists of two stainless steel rods
connected to a printed circuit board. A shielded four-conductor cable is
connected to the circuit board to supply power, enable the probe, and
monitor the pulse output. The circuit board is encapsulated in epoxy.
High-speed electronic components on the circuit board are configured as a
bistable multivibrator. The output of the multivibrator is connected to the
probe rods which act as a wave guide. The travel time of the signal on the
probe rods depends on the dielectric permittivity of the material
surrounding the rods and the dielectric permittivity depends on the water
content. Therefore, the oscillation frequency of the multivibrator is
dependent on the water content of the media being measured. Digital
circuitry scales the multivibrator output to an appropriate frequency for
measurement with a datalogger. The water content reflectometer output is
essentially a square wave. The probe output period ranges from about 14
microseconds with rods in air to about 42 microseconds with the rods
