LI-COR Stevens Hydra Probe II User manual

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 m3/m3
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.
1Connect to the Sutron 9210B datalogger using XTerm
software.
Be sure there are no SDI-12 sensors connected to the
datalogger yet.
2Click 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.
3Connect 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)
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Installation Guide

4Click Find.
The datalogger will find the sensor, which has a default
address of 0.
Figure 1. SDI addressing dialog.
5In the numeric dropdown menu (0* in Figure 1), select
sensor 0, then click Send....
A new dialog will open, where you can enter the
command A1 to change the sensor's address to 1. Then
click OK.
The sensor's address is now changed to 1.
6Now, select sensor 1 from the numeric dropdown
menu. Click Send.
Enter the command XM to query the sensor for its
default output. The default outputs should be H, J, F, G,
O, K, M, L, and N. If this is not displayed, send a new
command (XM=0). This sequence of parameters is
required for the standard LI-COR biomet packages,
where H represents soil moisture and F represents soil
temperature in °C. Refer to the Hydra Probe II manual
for more information on its SDI-12 parameters.
7Repeat steps 3 though 6 for each sensor.
You will need to give the sensor a unique address. For
LI-COR biomet packages, the addresses are 1, 2, and 3.
After configuring the sensors, click Close.
Installing the Probes
1Siting the Soil Moisture Probes.
Three or more probes may be required for some
sites.
Place the probes in undisturbed soil that is
representative of the site.
Probes can be inserted directly into the soil
surface, as shown, or inserted into the soil in a pit.
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2Install the Soil Moisture Probes.
Recommeneded depth of 5 cm below the soil
surface.
Press the probe into the soil until the base of the
tines is flush with the soil.
Be especially careful to avoid creating air pockets
when inserting the probe. Air pockets around the
tines will reduce the accuracy of measurements.
Note: Route the sensor cable(s) through an
opening in the enclosure prior to installing the
leads in the terminal strip.
Retrieving Data
If the system is configured to log biomet data in .ghg files
for processing in EddyPro software or the SMARTFlux®
System, see Field Setup for Logging Data in .ghg Files in
the Biomet System instruction manual. Otherwise, see
Retrieving Data in the Biomet System instruction manual
to get data from the datalogger memory.
Maintenance
Stevens Hydra Probe IIs are sealed after calibration and do
not require routine maintenance. Be mindful of the
following points:
Read and understand the manufacturer's instructions
provided with this product.
Do not attempt to disassemble the sensor. This will
damage the factory seal and invalidate the warranty.
Do not remove the Hydra Probe II from soil by pulling
on the cable.
Do not attempt to straighten a bent rod while it is
attached to the probe.
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