Decagon Devices 5TE User manual

5TE
Water Content, EC
and Temperature Sensors
Operator’s Manual
Version 7
Version 7Version 7
Version 7

Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman WA 99163
www.deca on.com
soils@deca on.com
©2007-2010 Deca on Devices, Inc.
All ri hts reserved

5TE Operator’s Manual
Table of Contents
i
Contents
1. Introduction . . . . . . . . . . . . . . . . . .1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . 1
Contact Information . . . . . . . . . . . . . . . . . . .2
Warranty Information . . . . . . . . . . . . . . . . . . 2
Seller’s Liability . . . . . . . . . . . . . . . . . . . . . .3
2. About t e 5TE . . . . . . . . . . . . . . . . 4
Background Info . . . . . . . . . . . . . . . . . . . . . .4
3.T eory . . . . . . . . . . . . . . . . . . . . . . 6
Volumetric Water Content . . . . . . . . . . . . . . 6
Temperature . . . . . . . . . . . . . . . . . . . . . . . . .6
Electrical Conductivity . . . . . . . . . . . . . . . . .6
Converting Bulk EC to Pore EC . . . . . . . . 7
Pore Water vs. Solution EC . . . . . . . . . . . . . . 9
4. Calibration . . . . . . . . . . . . . . . . . . 11
Dielectric Permittivity . . . . . . . . . . . . . . . . . 11
Mineral Soil Calibration . . . . . . . . . . . . . . . 11
Calibration in Non-Soil Media . . . . . . . . . . 12
5. Connecting to Logger . . . . . . . . .14
Connecting to an Em50/Em50R logger . . . 14
3.5mm Stereo Plug Wiring . . . . . . . . . . . . . . . . . . 15

5TE Operator’s Manual
Table of Contents
ii
Connecting to a Non-Decagon Logger . . . .15
Pigtail End Wiring . . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Communication . . . . . . . . . . . . . .18
Serial Communication . . . . . . . . . . . . . . . . . 18
Dielectric Permittivity . . . . . . . . . . . . . . . . . . . . . . . 19
Electrical Conductivity . . . . . . . . . . . . . . . . . . . . . 19
emperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
SDI-12 Communication . . . . . . . . . . . . . . .20
Sensor Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
7. Installing t e Sensors . . . . . . . . 23
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Removing the sensors . . . . . . . . . . . . . . . . .26
Multiple sensor Installation . . . . . . . . . . . . . 26
8. Campbell Scientific Programs . . 27
9. Troubles ooting&Sensor Care . 28
Datalogger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Sensor Cleaning . . . . . . . . . . . . . . . . . . . . . . 28
Cleaning Method . . . . . . . . . . . . . . . . . . . . . . . . . .30
Declaration of Conformity . . . . . . .31

5TE Operator’s Manual
1. Introduction
1
1. Introduction
Thank you for choosing Decagon’s 5TE for measuring
water content, temperature, and EC. This manual is
designed to help you understand the sensor’s features and
how to use this device successfully.
Specifications
Volumetric water content
Range:
Apparent dielectric permittivity (εa): 1 (air) to 80 (water)
Resolution:
ε
a
: 0.1 ε
a
(unitless) from 1-20, <0.75 ε
a
(unitless) from 20-80
VWC: 0.0008 m3/m3(0.08% VWC) from 0 to 50% VWC
Accuracy:
( ε
a
): ± 1 ε
a
(unitless) from 1-40 (soil range), ±15% from 40-80
(VWC):
• Using Topp equation: ±0.03 m3/m3(±3% VWC) typical
in mineral soils that have solution electrical conductiv-
ity < 10 dS/m
• Using medium specific calibration, ±0.01 - 0.02 m3/m3
(± 1-2% VWC) in any porous medium
Electrical Conductivity (bulk)
Range: 0-23 dS/m (bulk)
Resolution: 0.01 dS/m from 0 to 7 dS/m, 0.05 dS/m from 7
to 23 dS/m
Accuracy: ±10% from 0 to 7 dS/m, user calibration
required above 7 dS/m

5TE Operator’s Manual
1. Introduction
2
Temperature
Range: -40-50 °C
Resolution: 0.1 °C
Accuracy: ±1 °C
General
Dimensions: 10 cm (1) x 3.2 cm (w) x 0.7 cm (d)
Prong Length: 5.2 cm
Dielectric Measurement Frequency: 70 MHz
Measurement Time: 150 ms (milliseconds)
Power requirements: 3.6 - 15 VDC, 0.3 mA quiescent, 10
mA during 150 ms measurement
Output: RS232 (TTL) or SDI-12
Operating Temperature: -40-50 °C
Connector types: 3.5 mm (stereo) plug or stripped &
tinned lead wires (Pigtail)
Cable Length: 5m standard; custom cable length available
upon request
Datalogger Compatibility (not exclusive):
Decagon: Em50, Em50R
Campbell Scientific: Any logger with serial I/O (CR10X,
CR850, 1000, 3000, etc.)
Contact Information
If you need to contact Decagon:
•Call us at 800-755-2751 or [phone]
•Fax us at [phone]
•E-mail us at [email protected].
Warranty Information
All Decagon products have a 30-day satisfaction guarantee
and a one-year warranty.

5TE Operator’s Manual
1. Introduction
3
Seller’s Liability
Seller warrants new equipment of its own manufacture
against defective workmanship and materials for a period of
one year from date of receipt of equipment (the results of
ordinary wear and tear, neglect, misuse, accident and exces-
sive deterioration due to corrosion from any cause are not to
be considered a defect); but Seller’s liability for defective
parts shall in no event exceed the furnishing of replacement
parts F.O.B. the factory where originally manufactured.
Material and equipment covered hereby which is not manu-
factured by Seller shall be covered only by the warranty of
its manufacturer. Seller shall not be liable to Buyer for loss,
damage or injuries to persons (including death), or to prop-
erty or things of whatsoever kind (including, but not without
limitation, loss of anticipated profits), occasioned by or aris-
ing out of the installation, operation, use, misuse, nonuse,
repair, or replacement of said material and equipment, or
out of the use of any method or process for which the same
may be employed. The use of this equipment constitutes
Buyer’s acceptance of the terms set forth in this warranty.
There are no understandings, representations, or warranties
of any kind, express, implied, statutory or otherwise
(including, but without limitation, the implied warranties of
merchantability and fitness for a particular purpose), not
expressly set forth herein.

5TE Operator’s Manual
2. About the 5TE
4
2. About t e 5TE
The 5TE is designed to measure the water content, electrical
conductivity, and temperature of soil and growing media.
Using an oscillator running at 70 MHz, it measures the
dielectric permittivity of soil to determine the water content.
A thermistor in thermal contact with the sensor prongs pro-
vides the soil temperature, while the screws on the surface
of the sensor form a two-sensor electrical array to measure
electrical conductivity.
Background Info
In 2006, Decagon incorporated research from its EC-5 volu-
metric water content sensor into the ECH2O-TE, a sensor
which measured volumetric water content, temperature, and
electrical conductivity. The new 5TE uses the same theory
as the ECH2O-TE, but the location of the EC measurement
is in the stainless steel screws instead of gold traces. The use
of stainless steel screws has made the 5TE a more robust
sensor. Additionally, the 5TE utilizes a 5 point dielectric
calibration to provide dielectric permittivity measurements
more accurate than the previous ECH2O-TE.

5TE Operator’s Manual
2. About the 5TE
5
Figure 1: 5TE Components

5TE Operator’s Manual
3.Theory
6
3.T eory
Volumetric Water Content
The 5TE sensor uses an electromagnetic field to measure
the dielectric permittivity of the surrounding medium. The
sensor supplies a 70 MHz oscillating wave to the sensor
prongs that charges according to the dielectric of the mate-
rial. The stored charge is proportional to soil dielectric and
soil volumetric water content. The 5TE microprocessor
measures the charge and outputs a value of dielectric per-
mittivity from the sensor.
Temperature
The 5TE uses a surface-mounted thermistor to take temper-
ature readings. It is located underneath the sensor overmold,
next to one of the prongs, and will read the temperature of
the prong surface. The 5TE will output temperature in °C
unless otherwise stated in your preferences file in either the
ECH2O DataTrac or ECH2O Utility programs.
It is important to note that if the black plastic overmold of
the sensor is in direct sunshine, the temperature measure-
ment may read high. Exposure of the overmold to solar radi-
ation will also drastically decrease the life expectancy of the
sensor. We do not recommend that the sensor be installed
with the overmold in the sun.
Electrical Conductivity
Electrical conductivity (EC) is the ability of a substance to
conduct electricity and can be used to infer the amount of

5TE Operator’s Manual
3.Theory
7
polar molecules that are in solution. EC is measured by
applying an alternating electrical current to two electrodes,
and measuring the resistance between them. Conductivity is
then derived by multiplying the inverse of the resistance
(conductance) by the cell constant (the ratio of the distance
between the electrodes to their area).
The 5TE uses a 2-sensor array to measure the EC. The array
is located on the screws of two of the 5TE prongs. Small
amounts of oil from skin contact with the screws will
cause significant inaccuracy in the EC measurement.
See the sensor cleaning section at the end of this manual for
instructions on cleaning the sensors if contamination occurs.
The 5TE uses a two electrode array to measure the bulk EC
of the surrounding medium. The bulk EC measurement is
calibrated at the factory to be accurate within ±10% from 0
to 7 dS/m. This range is adequate for most field, greenhouse
and nursery applications. However, some special applica-
tions in salt affected soils may requires measurements with
bulk EC greater than the specified range. The 5TE will mea-
sure up to 23.1 dS/m bulk EC, but user calibration is
required above 7 dS/m. Additionally, EC measurements
above 7 dS/m are very sensitive to contamination of the
electrodes by skin oils, etc. Be sure to read sensor cleaning
section at the end of the manual if you plan to measure the
EC of salty soils.
Converting Bulk EC to Pore EC
For many applications, it is advantageous to know the elec-
trical conductivity of the solution contained in the soil pores
(σp), which is a good indicator of the solute concentration in

5TE Operator’s Manual
3.Theory
8
the soil. Traditionally, σphas been obtained by extracting
pore water from the soil and measuring σpdirectly. As one
would expect, this is a time consuming and labor intensive
process.
The 5TE measures the electrical conductivity of the bulk
soil surrounding the sensors (σb). A considerable amount of
research has been conducted to determine the relationship
between σband σp. Recent work by Hilhorst (2000), has
taken advantage of the linear relationship between the soil
bulk dielectric permittivity (εb) and σbto allow accurate
conversion from σbto σpif the εbis known. The 5TE mea-
sures εband σbnearly simultaneously in the same soil vol-
ume. It is therefore well suited to this method.
The pore water conductivity can be determined from (see
Hilhorst, 2000 for derivation):
(1)
where σpis the pore water electrical conductivity (dS/m); εP
is the real portion of the dielectric permittivity of the soil
pore water (unitless); σbis the bulk electrical conductivity,
(dS/m), which is measured directly by the 5TE; εbis the real
portion of the dielectric permittivity of the bulk soil (unit-
less); ε
σb=0 is the real portion of the dielectric permittivity
of the soil when bulk electrical conductivity is 0 (unitless).
ε
p can be calculated from soil temperature using:
ε
p= 80.3 - 0.37 * (Tsoil - 20) (2)
where Tsoil is the soil temperature (C) measured by the 5TE.
σpεpσb
εbεσb0= –
---------------------------
=

5TE Operator’s Manual
3.Theory
9
ε
b is also measured by the 5TE. Raw VWC counts can be
converted to bulk dielectric by the 5TE dielectric calibra-
tion:
Finally, ε
σ b=0
is an offset term loosely representing the
dielectric permittivity of the dry soil. Hilhorst (2000) recom-
mended that ε
σ b=0
= 4.1 be used as a generic offset. However,
our research in several agricultural soils, organic, and inor-
ganic growth media indicates that ε
σ b=0
= 6 results in more
accurate determinations of σ
p
. Hilhorst (2000) offers a sim-
ple and easy method for determining for individual soil types,
which will improve the accuracy of the calculation of σ
p
in
most cases.
Our testing indicates that the above method for calculating
σpresults in good accuracy (± 20%) in moist soils and other
growth media. In dry soils where VWC is less than about
0.10 m3/m3, the denominator of equation 1 becomes very
small, leading to large potential errors. We recommend that
σpnot be calculated in soils with VWC < 0.10 m3/m3using
this method.
Pore Water vs. Solution EC
As noted in the previous section, pore water electrical con-
ductivity can be calculated from bulk EC using the sensor-
measured dielectric permittivity of the medium. However,
pore water EC is not the same as solution EC. Pore water
EC is the electrical conductivity of the water in the pore
space of the soil. One could measure this directly if the soil
was squeezed under high pressure to force water out of the
50
Raw
b
ε
ε =
(3)

5TE Operator’s Manual
3.Theory
10
soil matrix and that water was collected and tested for EC.
Solution EC is the electrical conductivity of pore water
removed from a saturated paste. In this case, the soil is wet-
ted with distilled water until the soil saturates, then the soil
is placed on filter paper in a vacuum funnel and suction is
applied. An electrical conductivity measurement on the
water removed from the sample will give the solution elec-
trical conductivity. Theoretically, the two are related by the
bulk density. An example calculation will illustrate this rela-
tionship: A soil is at 0.1 m3/m3VWC, has a pore water EC
of 0.7 dS/m, and a bulk density of 1.5 Mg/m3. We can cal-
culate the solution EC as follows.
In this example, ø is the porosity, ρ
bis bulk density,
ρ
sis
density of the minerals (assumed to be 2.65 Mg/m3), sub-
script d is distilled water, and θ is volumetric water content.
We assume that the EC of the distilled water is 0 dS/m. In
practice, solution EC calculated from this method and solu-
tion EC taken from a laboratory soil test may not agree well
because wetting soil to a saturated paste is very imprecise.
Reference
Hilhorst, M.A. 2000. A pore water conductivity sensor.
Soil Science Society of America Journal 64:6 1922-
1925
( ) ( )
dS/m162.0
0.43 01.07.0
ECSolution
43.0
65.2 5.1
11
=
+
=
−+
=
=−=−=
φθφσθσ
ρ
ρ
φ
dp
s
b

5TE Operator’s Manual
4. Calibration
11
4. Calibration
Dielectric Permittivity
Each 5TE sensor has been calibrated to measure dielectric
permittivity (εa) accurately in the range of 1 (air) to 80
(water). The unprocessed raw values reported by the 5TE in
standard serial communication have units of εa*50. When
used in SDI-12 communication mode, the unprocessed val-
ues have units of εa(for 5TE board versions R2-04 and
older, units are, εa*100).
Mineral Soil Calibration
Numerous researchers have studied the relationship
between dielectric permittivity and volumetric water con-
tent (VWC) in soil. As a result, the soil science literature is
littered with various transfer equations used to predict VWC
from measured dielectric permittivity. You are free to use
any of these various transfer equations to convert raw
dielectric permittivity data from the 5TE into VWC. In
Decagon’s ProCheck reader and DataTrac and ECH2O Util-
ity software packages, if the mineral soil calibration option
is chosen, raw dielectric permittivity values from are con-
verted to VWC using the well known Topp equation (Topp
et al. 1980):
VWC = 4.3x10-6 εa3- 5.5x10-4 εa2 + 2.92x10-2 εa- 5.3x10-2
Our tests have shown that a properly installed 5TE sensor
installed in a normal mineral soil with saturation extract

5TE Operator’s Manual
4. Calibration
12
electrical conductivity <10 dS/m, the Topp equation will
result in measurements within ±3% VWC of the actual soil
VWC. If you require more accurate VWC than ±3% or are
working in a soil with very high electrical conductivity, or
non-normal mineralogy, then it may be necessary to conduct
a soil specific calibration for your 5TE sensor which will
improve the accuracy to 1-2% for any soil. For more infor-
mation on how to perform your own soil-specific calibra-
tion, or to have Decagon’s calibration service perform one
for you, visit us online at http://www.decagon.com.
Calibration in Non-Soil Media
Decagon has performed calibrations with the 5TE in several
non-soil growth media. The following are suggested cali-
bration equations for some common materials.
Potting Soil
VWC = 2.25x10-5 εa3- 2.06x10-3 εa2 + 7.24x10-2 εa- 0.247
Rockwool
VWC = -1.68x10-3 εa2 + 6.56x10-2 εa+ 0.0266
Perlite
VWC = -1.07x10-3 εa2+ 5.25x10-2 εa- 0.0685
Decagon will develop additional calibration equations for
various other growth media as opportunities arise. Please
check the Decagon website (http://www.decagon.com) or
contact Decagon for the status of this ongoing research.
The 5TE can accurately read VWC in virtually any porous
medium if a custom calibration is performed. For informa-

5TE Operator’s Manual
4. Calibration
13
tion on how to perform your own medium-specific calibra-
tion, or to have Decagon’s calibration service perform one
for you, visit http://www.decagon.com.
Reference
Topp, G.C., J.L. David, and A.P. Annan 1980. Electromag-
netic, Determination of Soil Water Content: Measure-
ment in Coaxial Transmission Lines. Water Resources
Research 16:3. p. 574-582.

5TE Operator’s Manual
5. Connectin to Lo er
14
5. Connecting to Logger
The 5TE sensor was designed to be used with Decagon’s
Em50, Em50R or the ProCheck handheld reader. The stan-
dard sensor (with 3.5 mm stereo connector) quickly con-
nects to and is easily configured within a Decagon logger or
selected in ProCheck.
The 5TE sensor incorporates several features that also make
it an excellent sensor for use with third party loggers. The
sensor may be purchased with stripped and tinned wires
(pigtail) for terminal connections. Visit www.decagon.com/
support/literature to get extensive directions on how to inte-
grate the 5TE sensor into third party loggers.
5TE sensor comes standard with a 5 meter cable. Sensors
may be purchased with custom cable lengths for an addi-
tional fee (on a per-foot fee basis). Decagon has tested its
digital sensor successfully up to 1000 meters (3200 ft). This
option eliminates the need for splicing the cable (a possible
failure point).
Connecting to an Em50/Em50R logger
The 5TE has been designed to work specifically with the
Em50 datalogger. Simply plug the 3.5mm “stereo plug”
connector. directly into one of the five sensor ports.
The next step is to configure your logger port for the 5TE
and set the measurment interval, this may be done using
either ECH2O Utility or ECH2O Utility Mobile (see respec-
tive manuals). Please check your software version to ensure

5TE Operator’s Manual
5. Connectin to Lo er
15
it will support the 5TE. To update your software to the latest
version, please visit Decagon’s software download site:
www.decagon.com/support/downloads.
The following software support the 5TE sensor:
ECH2O Utility 1.12 or greater
ECH2O Utility Mobile 1.18 or greater
ECH2O DataTrac 2.77 or greater
To download data from the logger to your computer, you
will need to use the ECH2O Utility, ECH2O DataTrac or a
terminal program on your computer.
3.5mm Stereo Plug Wiring
Connecting to a Non-Decagon Logger
5TE sensor may be purchased for use with non-Decagon
data loggers. These sensors typically come pre-configured
with stripped and tinned (pigtail) lead wires for use with
screw terminals. Refer to your distinct logger manual for
details on wiring. Our integrator’s guide gives detailed
instructions on connecting the 5TE sensor to non-Decagon
Digital
out
Ground
Excitation

5TE Operator’s Manual
5. Connectin to Lo er
16
loggers. Please visit www.decagon.com/support/literature
for the complete
integrator’s guide.
Pigtail End Wiring
Connect the wires to the data logger as shown, with the sup-
ply wire (white) connected to the excitation, the digital out
wire (red) to a digital input, the bare ground wire to ground
as illustrated below.
NOTE: The acceptable range of excitation voltages is from
3-15 VDC. If you wish to read the 5TE with the Campbell
Digital out (Red)
Ground (Bare)
Excitation (White)
Sensor cable
Switched
3-15V DC
G
Supply Digital
out Ground
Datalogger
Digital
In