Soil Probe—Stevens Hydra Probe II
The Stevens Hydra Probe II measures soil moisture and
temperature and provides that data to the Sutron datalogger
using the SDI-12 communication protocol. This document
provides basic installation and operation guidelines for
using the Hydra Probe II in LI-COR eddy covariance
systems with a biomet system running Biomet_100,
Biomet_101, Biomet_102, and Biomet_103 programs. Refer
to the Hydra Probe II operating instructions for more
information: http://www.stevenswater.com/soil_moisture_
sensors/
Hydra Probe II
Operating Temperature Range:
-10 to 65 °C
Voltage Range:
9 to 20 VDC
Measurement Range:
0.0 to Saturation
Accuracy:
±0.03 m
3
/m
3
Power Requirements:
<1mA idle; 30 mA active
Addressing the Hydra Probe II for SDI-12
Communication
SDI (Serial Digital Interface) communication is a standard
for interfacing data recorders with micro-processor based
sensors. The SDI protocol enables data from multiple
sensors to be recorded over a single SDI connection. In
order to work, each SDI sensor must have a unique address.
This section describes how to address the Hydra Probe
II with the Sutron 9210B datalogger.
Stevens Hydra Probes are supported by datalogger programs
Biomet_100, Biomet_101, Biomet_102, and Biomet_103. For
custom programs, use the SDI-12 block and configure it as
described in
Soil Probe Blocks (Stevens Hydra Probe II)
in the Biomet System instruction manual.
1
Connect to the Sutron 9210B datalogger using XTerm
software.
Be sure there are no SDI-12 sensors connected to the
datalogger yet.
2
Click on the Sensors tab. Click the SDI button on the
bottom right.
This will present a new SDI Interface window.
Sometimes this is referred to as entering
Transparent Mode
.
3
Connect the first Hydra Probe II sensor (the one you
will designate as Sensor 1).
Hydra Probe II; 1, 2, and 3
Color
Desc.
DIN Terminal
Black
Ground
16
Red
Power
17
Blue
SDI-12 Signal
18
Wire Lead Connections
Color
DIN Terminal
Datalogger Terminal
30 cm Black
16
SDI-12 GND (B20)
30 cm Red
17
SDI-12 Power (B21)
30 cm Blue
18
SDI-12 Data (B22)
1
Installation Guide
