Initial Setup
2-17
The 8100-204 Theta Probe has four bare wire leads for connection to the Auxiliary
Sensor Interface. Voltage channels 1-4 (V1-V4) can be used with the ECH
2
O soil
moisture probe; the soil probe must be set up in software. The 4-wire adapter
cable has red, blue, yellow and green wires that are connected to V OUT 5VDC
SWITCHED(+),V OUT 5VDC SWITCHED(-), V4(+), and V4(-) respectively, as
shown in Figure 2-16.
V1
V IN
10.5-28VDC
3A MAX
V OUT
5VDC
30mA
V OUT
5VDC
30mA
SWITCHED
V2
Yellow (+V IN)
Red (power supply +)
Blue (power supply -)
V3 V4 T1 T2 T3 T4
+
GND
+
GND
+
GND
+
GND
GND
GND
+
-
+
-
+
-
+
-
+
-
+
-
+
-
Green (ground)
Auxiliary Sensor Interface Terminal Strips
type
ML2x
o
Probe
Theta
Figure 2-16. Theta soil moisture probe connection to Auxiliary Sensor Interface.
Slope and offset coefficients for linear input devices need to be entered into the
Windows Application Software and/or the Interface Software for Apple iOS before
using the soil probe. Note that the 8100-204 and 8150-204 use different
linearization coefficients, based on the organic content of the soil into which the
probe is inserted. In general, if the soil is classified as a Mineral soil, with < 7%
organic content, the probe uses one set of coefficients, and if the soil is classified as
an Organic soil, with > 7% organic content, the probe uses a second set of
coefficients, as follows:
Soil Type
Mineral
Organic
Use for organic
contents:
< 7%
> 7%
Bulk density
range (g/cm
-3
)
1.25 - 1.5 g/cm
-3
0.2 - 0.7 g/cm
-3
Use for bulk
densities:
> 1.0 g/cm
-3
< 1.0 g/cm
-3
Slope
0.529
0.577
Offset
-0.060
-0.026
It is possible to perform soil-specific calibration of the soil moisture probe to obtain
linearization coefficients; refer to the ThetaProbe ML2x instruction manual for more
information.
To Next Page
Loading...
