Decagon Devices EC-5 User manual

EC-5
Soil Moisture Sensor
User’s Manual
Version 2

Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman WA 99163 USA
[phone]
Trademarks:
“ECH2O” is a registered trademark
of Decagon, Devices, Inc All rights reserved..
©2001-2012 Decagon Devices, Inc.
All rights reserved.

EC-5 User’s Manual
Table of Contents
i
Contents
1. Introduction . . . . . . . . . . . . . . . . 1
EC-5 Specifications . . . . . . . . . . . . . . . . . . 1
Customer Support . . . . . . . . . . . . . . . . . . . 2
Warranty Information . . . . . . . . . . . . . . . 2
Seller’s Liability . . . . . . . . . . . . . . . . . . . . . 2
2. About the EC-5 . . . . . . . . . . . . . . 4
Sensor Features . . . . . . . . . . . . . . . . . . . . . 4
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . 5
3.5mm Plug Wiring . . . . . . . . . . . . . . . 5
Wiring to Non-Decagon Data Loggers 5
Extended cable lengths . . . . . . . . . . . . . . . 6
3. Installing the Sensors . . . . . . . . . 7
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Orientation . . . . . . . . . . . . . . . . . . . . . . 8
Removing the Sensor . . . . . . . . . . . . . . 8
4. Collecting Data . . . . . . . . . . . . . . 9
Data Logger Requirements . . . . . . . . . . . . 9
Connecting to a Data Logger . . . . . . . . . 10
Sample Program . . . . . . . . . . . . . . . . . . . 10
SCWin (Short Cut) Directions . . . . . . . . 11
Calibration . . . . . . . . . . . . . . . . . . . . . . . . 13
Troubleshooting . . . . . . . . . . . . . . . . . . . . 16
Declaration of Conformity . . . . . 17
Index . . . . . . . . . . . . . . . . . . . . . . . 19

EC-5 User’s Manual
1. Introduction
1
1. Introduction
EC-5 Specifications
Measurement Time: 10ms (milliseconds)
Accuracy: at least 0.03 m3/m3all soils, up to 8 dS/m
With soil-specific calibration: ±.02 m3/m3(±2%)
Resolution: 0.001 m3/m3VWC in mineral soils, 0.25%
in growing media
Power Requirements: 2.5VDC - 3.6VDC @ 10mA
Output: 10-40% of excitation voltage (250-1000mV at
2500mV excitation)
Operating Environment: -40 to +60 °C
Range of Measurement: 0 to saturation
Sensor dimensions: 8.9cm x 1.8cm x 0.7cm
Cable length: 5m standard, custom lengths or extension
cables are available
Connector types: 3.5 mm plug or stripped and tinned
lead wires
Data Logger Compatibility (not exclusive):
Decagon: Em5b, Em50 series loggers
Campbell Scientific: CR10X, 21X, 23X, CR1000,
CR3000, etc.

EC-5 User’s Manual
1. Introduction
2
Customer Support
If you ever need assistance with your EC-5, or if you
just have questions or feedback, there are several ways
to contact us. Customer service representatives are
available to speak with you Monday thru Friday,
between 7am and 5pm Pacific time.
NOTE: If you purchased your EC-5 through a distribu-
tor, please contact them for assistance.
E-mail:
[email protected] or [email protected]
Phone:
1-509-332-5600
Fax:
1-509-332-5158
If contacting us by email or fax, please include as part of
your message your name, address, phone, and fax num-
ber along with a description of your problem.
Warranty Information
The EC-5 has a 30-day satisfaction guarantee and a one-
year warranty.

EC-5 User’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 excessive 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 manufactured
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
property or things of whatsoever kind (including, but
not without limitation, loss of anticipated profits), occa-
sioned by or arising out of the installation, operation,
use, misuse, nonuse, repair, or replacement of said mate-
rial 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 under-
standings, representations, or warranties of any kind,
express, implied, statutory or otherwise (including, but
without limitation, the implied warranties of merchant-
ability and fitness for a particular purpose), not
expressly set forth herein.

EC-5 User’s Manual
2. About the EC-5
4
2. About the EC-5
The two-prong design and higher measurement fre-
quency allows the EC-5 to measure VWC from 0 to
100% (VWC of saturated soils is generally 40-60%
depending on the soil type) and allows accurate mea-
surement of all soils and soilless medias with a wide
range of salinities.
Sensor Features
Fig. 1: EC-5 diagram
Circuitry
Sensor

EC-5 User’s Manual
2. About the EC-5
5
Wiring Diagrams
3.5mm Plug Wiring
The EC-5 comes with a 3.5mm “stereo plug” connector.
This allows for rapid connection directly to Decagon’s
Em50 and Em5 loggers and the ProCheck. Below is a
diagram showing the wiring configuration for this con-
nector.
Fig. 2: 3.5mm “Stereo Plug” wiring configuration
Wiring to Non-Decagon Data Loggers
Models with stripped and tinned leads are pre-config-
ured for connecting to non-Decagon data loggers. Sim-
ply wire the lead into the data logger as described in
“Connecting to a Data Logger” in Chapter 4.
If your model uses the standard 3.5mm plug, you have
two choices when attaching the sensor to non-Decagon
data loggers. First, you can clip off the plug on the sen-
sor cable, strip and tin the wires, and wire it directly into
the data logger. This has the advantage of creating a
direct connection with no chance of the sensor becom-
ing un-plugged; however, it then cannot be used in the
future with a Decagon Em50 or Em5 logger. The other
Analog
out
Ground
Excitation

EC-5 User’s Manual
2. About the EC-5
6
choice is to obtain an adapter cable from Decagon. The
3-wire sensor adapter cable has a connector for the sen-
sor jack on one end, and three wires on the other end for
connection to a data logger (this type of wire is often
referred to as a “pigtail” adapter). Both the sensor wire
and adapter cable wire have the same wire output
(shown in Fig. 3); the white wire is excitation, red is
output, and the bare wire is ground.
Fig. 3: 3-wire cable wiring configuration
Extended cable lengths
Decagon recommends that you purchase customized
cable lengths if your project requires longer cable leads.
Custom cable lengths may be requested with a 3.5mm
connector or stripped & tinned end.
Analog out (Red)
Ground (Bare)
Excitation (White)
Sensor cable

EC-5 User’s Manual
3. Installing the Sensors
7
3. Installing the Sensors
When selecting a site for installation, it is important to
remember that the soil adjacent to the sensor surface has
the strongest influence on the sensor reading and that
the sensor measures the volumetric water content.
Therefore any air gaps or excessive soil compaction
around the sensor can profoundly influence the read-
ings. Also, do not install the sensors adjacent to large
metal objects such as metal poles or stakes. This can
attenuate the sensor’s electromagnetic field and
adversely affect output readings. Because the EC-5 has
gaps between its prongs, it is also important to consider
the size of the media you are inserting the sensor into. It
is possible to get sticks, bark, roots or other material
stuck between the sensor prongs, which will adversely
affect readings. Finally, be careful when inserting the
sensors into dense soil, as the prongs will break if exces-
sive sideways force is used when pushing them in.
Procedure
When installing the EC-5, it is best to maximize contact
between the sensor and the soil.
1. The EC-5 sensor was designed for easy installation
into the soil. After digging a hole to the desired
depth, push the prongs on the sensor into undis-
turbed soil at the bottom of the hole or into the side-
wall of the hole. Make sure that the prongs and
black overmolding are buried completely as shown
below.

EC-5 User’s Manual
3. Installing the Sensors
8
The sensor may be difficult to insert into extremely
compact or dry soil. If you have difficulty inserting
the sensor, try loosening the soil somewhat or wet-
ting the soil. Never pound it in!
2. Carefully backfill the hole to match the bulk density
of the surrounding soil. Be careful not to bend the
black overmolding connecting the sensor to the
cable.
To watch a video on proper installation of the sensor go
to www.decagon.com/install.
Orientation
The sensor can be oriented in any direction. However,
orienting the flat side perpendicular to the surface of the
soil will minimize effects on downward water move-
ment.
Removing the Sensor
When removing the sensor from the soil, do not pull it
out of the soil by the cable! Doing so may break inter-
nal connections and make the sensor unusable.

EC-5 User’s Manual
4. Collecting Data
9
4. Collecting Data
Data Logger Requirements
The EC-5 sensor is designed to work most efficiently
with Decagon’s 5-channel Em5b, Em50, or ProCheck
handheld readout. All Decagon readout devices use a
3.0V excitation.
The sensors however, may be adapted for use with other
data loggers, such as those from Campbell Scientific,
Inc., for example. The EC-5 requires an excitation volt-
age in the range of 2 to 3.6 volts. The sensors produce
an output voltage that depends on the dielectric constant
of the medium surrounding the sensor, and ranges
between 10 and 50% of the excitation voltage. Any data
logger which can produce a 2.5 to 3.6V excitation with
approximately 10 millisecond duration and read a volt-
level signal with 12-bit or better resolution should be
compatible with the EC-5 sensor. The current require-
ment for the EC-5 is 10mA at 2.5V.
NOTE: EC-5 sensors are intended only for use with
data loggers and readout devices which can provide
short excitation pulses, leaving the sensors turned off
most of the time. Continuous excitation not only wastes
battery power, but may, under certain circumstances,
cause the sensor to exceed government specified limits
on electromagnetic emissions. Do not continuously
power the EC-5 sensor.

EC-5 User’s Manual
4. Collecting Data
10
Connecting to a Data Logger
Connect the wires to the data logger as shown, with the
supply wire (white) connected to the excitation, the ana-
log out wire (red) to an analog input, and the bare
ground wire to ground:
Fig. 5: Data logger configuration
Sample Program
The following program is an example that can be used
with Campbell Scientific’s CR10X data logger and our
EC-5 sensor at a 2500mV excitation:
;{CR10X}
; Example ECH2O Data Logger Program for CR10X
; Wiring:
; White: Excitation Channel 1
; Red: Input Single Ended Channel 1
; Black: Ground
*Table 1 Program
Exc. HLG
Supply Analog
out Ground
Data Logger
aog
Exc. HLG
Supply Analog
out Ground
Data Logger
Analog
In

EC-5 User’s Manual
4. Collecting Data
11
01: 1 Execution Interval (seconds)
; Factory calibration equations for ECH2O
; probes convert mV output of ECH2O to
; volumetric water content (VWC, m3/m3)
; EC-5: VWC = 0.00119 * mV - 0.400
1: Excite-Delay (SE) (P4)
1: 1 Reps
2: 5 2500 mV Slow Range
3: 1 SE Channel
4: 1 Excite all reps w/Exchan 1
5: 1 Delay (0.01 sec units)
6: 2500 mV Excitation
7: 1 Loc [ Probe_VWC ]
8: .00119 Multiplier
9: -.4 Offset
*Table 2 Program
02: 0.0000 Execution Interval (seconds)
*Table 3 Subroutines
End Program
SCWin (Short Cut) Directions
The following are instructions for using Campbell Sci-
entific’s SCWin (Short Cut) program to read the EC-5
soil moisture sensor.
1. Download EchoCSI.zip from http://www.deca-
gon.com/appnotes/EchoCSIappnote.pdf.
2. Unzip the folder EchoCSI.zip.
3. Locate the file containing SCWin.exe. It should be
in C:\Program Files\Campbellsci\SCWin. Place the

EC-5 User’s Manual
4. Collecting Data
12
following files from the unzipped EchoCSI.zip
folder into the folder with SCWin.exe:
AM1632Z.MUX
AM416Z.MUX
EC10.SCS
EC101632.SCS
EC10416.SCS
EC20.SCS
EC201632.SCS
EC20416.SCS
EC5.SCS
EC5632.SCS
EC5416.SCS
SCWIN-DECAGON.CNT
SCWIN-DECAGON.HLP
Note: If you are not able to find this directory path,
search for the folder that contains SCWIN.exe and place
the files into that folder.
4. Open up SCWin.exe (Short Cut). If you are using a
V.3 copy of LoggerNet, there is a tab for SCWin
(Short Cut) on the tool bar.
5. Select “New” to start a new program to read the EC-5.
a. Select the data logger you will be using to read the
sensors.
b. Select the measurement interval (a shorter measure-
ment interval, i.e. 1 sec., is sometimes desirable when
testing the sensor).
6. Click on Sensors (this should open a new page with
a file tree on it).

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4. Collecting Data
13
7. Under the “Sensors” file tree, double-click on
“Meteorological” and then select “Soil Moisture.”
8. Choose “EC-5” Sensor.
Calibration
Decagon’s ECH2O Utility, and DataTrac3 automatically
apply factory calibrations to the sensors’ output data.
However, this general calibration may not be applicable
for all soil types. For added accuracy we encourage our
customers to perform soil-specific calibrations.
The calibration equation that you will use depends on
where you will be using it. If you will be using it with
sensors connected to a non-Decagon data logger you
will need to use the 2500 mV calibration. If you use any
Decagon software (DataTrac3, ECH2O Utility, etc.) or
the user calibration menu in the ProCheck, you will
need to use the RAW calibration. The difference
between the two is the slope constant. To increase the
resolution of the sensor output, Decagon uses all avail-
able increments of the 12-bit number (value of 4096)
where the measurement is stored. Thus, the output of the
sensors read by the ProCheck and Decagon loggers
must be multiplied by 0.61 AND the 2500 mV slope to
give the right value.
Sensor Calibration Values
Following is a list of the both the millivolt and RAW
calibration values for the EC-5, where is the volumet-
ric water content, mV is the millivolt output of the sen-
sor, and where xis the RAW sensor output.

EC-5 User’s Manual
4. Collecting Data
14
The EC-5 is much less sensitive to variation in texture
and electrical conductivity because it runs at a much
higher measurement frequency. Therefore, its general
calibration equation should apply for all mineral soils up
to 8 dS/m saturation extract. Its calibration equations are
shown below for mineral soil, potting soil, and rock-
wool growing media:
Dielectric Permittivity
Dielectric permittivity can be used to determine volu-
metric water content using external published equations
such as the Topp equation. Dielectric permittivity is
given by
= 1/(-1.1x 10-9RAW3 x 10-6
RAW2x 10-3 RAW
where RAW is the output from the Decagon data logger
using 3V excitation. If you are using a non-Decagon
data logger, dielectric permittivity is given by
= 1/(x 10-9mV3x 10-6mV2
x 10-3 mV
Mineral Soils
According to our tests, a single calibration equation will
generally suffice for all mineral soil types with electrical
conductivities from 0.1 dS/m to 10 dS/m saturation
extract. Volumetric water content (ø) is given by
ø = 8.5 * 10-4 * RAW - 0.48 (1)

EC-5 User’s Manual
4. Collecting Data
15
where RAW is the output from the Decagon data logger
using 3V excitation. If you are using a non-Decagon
data logger, VWC is given by
ø = 11.9 * 10-4 * mV - 0.401 (2)
where mV is the output of the sensor when excited at
2500 mV. Please note that the equation will reach a
maximum at ~60% volumetric water content (VWC) in
pure water. To display data on a scale from 0 to 100%,
VWC should be modeled with a quadratic equation
(which would result in a 100% VWC in water), but a
linear equation fits the mineral soil VWC range as well
as the quadratic, and linear equations are easier to deal
with, especially since mineral soil typically saturates at
~40 - 50% VWC.
Potting soil
The following equations can be used to convert EC-5
output to water content in potting soil. We tested several
types of potting soil (Sunshine mix, Miracle Grow Pot-
ting Mix, and Custom Nursery soil) at several salinities
and found that VWC is given by
ø = 1.3 * 10-3 * RAW - 0.696 (3)
for a Decagon data logger or
ø = 2.11 * 10-3 * mV - 0.675 (4)
for a data logger with 2500mV excitation.

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4. Collecting Data
16
Rockwool
The EC-5 was calibrated in Grodan Master rockwool
with solution electrical conductivities of 0.2, 1.0, 1.5,
2.0, and 4.5 dS/m. Volumetric water content can be cal-
culated using
ø = 6.28 * 10-7 * RAW2+ 1.37 x 10-4 * RAW - 0.183(5)
for a Decagon data logger or
ø = 2.63 * 10-6 * mV2+ 5.07 x 10-4 * mV - 0.0394(6)
for a data logger with 2500 mV excitation.
NOTE : These calibration constants only apply to
2500mV excitations; use of these numbers with any other
excitation voltage will result in erroneous readings !
Troubleshooting
If you encounter problems with the EC-5, they most
likely will manifest themselves in the form of incorrect
or erroneous readings. Before contacting Decagon about
the sensor, do the following:
• Check to make sure the connections to the data
logger are both correct and secure.
• Ensure that your data logger’s batteries are not
dead or weakened.
If you encounter problems that aren’t due to the data
logger, please contact Decagon at [phone] or at
[email protected].