Hydronix Hydro-View HV02, User Manual

Page: 32 / 82

SENSOR SET-UP MENU
32
HYDRO-VIEW USER GUIDE
D0022
REV 1.06
The basic calibration procedure is as follows...
⇒
Monitor the
Unscaled Input
display on Hydro-View and record either the
instantaneous or average value shown (as appropriate for your application) at the
time of taking a sample.
⇒
Perform a
desiccation
or
bake out
test on the sample to establish the true moisture
content by weighing the sample before and after drying. Recommended
procedures are given later in this guide in Calibration and sampling techniques
⇒
Enter the results into a material table using the Hydro-View
Sensor Calibration
page.
Each material calibration table allows a compensating value to be entered. This is known
as the
Surface Saturated Dry
or
SSD
offset and represents a value which will be
subtracted from the moisture value before is it displayed or otherwise output. Its purpose
is to adjust the displayed moisture reading for the absorption properties of the material.
The Hydro-View uses the two calibration values to compute a calibration line for the
material of the form…
y = mx + c
where
y
is a moisture value,
x
is the corresponding unscaled input from the sensor,
m
is
the slope of the calibration line and
c
is the intercept.
The computed values for
m
and
c
are indicated on the calibration display.
Further details will be found in Calibration and sampling techniques on page 42.
Sensor set-up menu
Hydronix moisture sensors output a voltage signal, which varies according to the moisture
content of the material. However, the signal may be disturbed by the presence of other
materials such as mixer blades passing in close proximity to the sensor. These unwanted
signals form 'noise' in the system and would result in errors in the reading if they were not
filtered out. Fortunately these noise 'spikes' are characterised by being of short duration
and having relatively fast rise and fall times and may therefore be effectively eliminated by
filtering the input signal in a manner appropriate to the application.
The Hydro-View uses the parameter list in the
Sensor set-up
menu to control how the raw
voltage signal from the sensor is processed to derive the moisture content.
Parameter Default
Value Description
Type 1 Sensor type.
Defines the signal processing algorithm used for this sensor.
Samples 5 Number of sensor samples used to evaluate the ‘NOW’
moisture reading. Range 1
Æ 1000.
A/H delay 0 Time interval between the average/hold input going active
and the start of averaging. Range 0.0
Æ 100.0 seconds.
Sync Delay 0.00 Time interval between a sync signal arriving at a digital input
and a sensor reading being taken. Used to synchronise the
readings to external events.
The Sensor Type parameter must be set to 2 for this to be
used.
Range 0.00
Æ 10.00 seconds.