Onset HOBO HOBOnet RXW Series User manual

HOBOnet® Wireless Sensor Network
RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
23962-C
This sensor measures leaf wetness and is designed to work with the HOBOnet® (HOBO RX)
Wireless Sensor Network in which data is transmitted wirelessly from the sensor mote across
the network to the station and then uploaded to HOBOlink® web-based software. With
HOBOlink, you can monitor sensor readings, view graphs, set up alarms, download data, and
more.
Specifications
Sensor
Measurement Range
0 (dry) to 100% (wet)
Sensor Type
Capacitive grid
Interchangeability
Between Sensors (Over
the Range 10
–90% Wet)
±10%
Repeatability
±5%; see Note 1
Resolution
0.59%
Stability (Drift)
< ±5% per year (in typical growth conditions)
Service Life
3 years in typical growth conditions
Wireless Mote
Operating Temperature
Range
-25° to 60°C (-13° to 140°F) with rechargeable batteries
-40 to 70°C (-40 to 158°F) with lithium batteries
Radio Power
12.6 mW (+11 dBm) non-adjustable
Transmission Range
Reliable connection to 457.2 m (1,500 ft) line of sight at 1.8 m (6 ft) high
Reliable connection to 609.6 m (2,000 ft) line of sight at 3 m (10 ft) high
Wireless Data Standard
IEEE 802.15.4
Radio Operating
Frequencies
RXW-LWA-900: 904–924 MHz
RXW-LWA-868: 866.5 MHz
RXW-LWA-921: 921 MHz
RXW-LWA-922: 916–924 MHz
Modulation Employed
OQPSK (Offset Quadrature Phase Shift Keying)
Data Rate
Up to 250 kbps, non-adjustable
Duty Cycle
<1%
Maximum
Number of
M
otes
50 motes per one RX Wireless Sensor Network
Battery Type/
Power
Source
Two AA 1.2 V rechargeable NiMH batteries powered by built-in solar
panel or two AA 1.5 V lithium batteries for operating conditions of -40 to
70°C (-40 to 158°F)
Battery
Life With NiMH batteries: Typical 3–5 years when operated in the
temperature range -20° to 40°C (-4°F to 104°F)
and positioned toward the
sun (see Deployment and Mounting), operation outside this range will
reduce the battery service life
With lithium batteries: 1 year, typical use
Memory
16 MB
Dimensions
Sensor grid: 4.7 x 5.1 cm (1.8 in x 2.0 inches)
Sensor housing: 12.2 x 1.8 cm (4.8 in x 0.7 inches)
Mounting bracket: 20 x 3 x 0.5 cm (8 x 1.3 x 0.2 inches)
Cable length: 2 m (6.56 ft)
Mote: 16.2 x 8.59 x 4.14 cm (6.38 x 3.38 x 1.63 inches)
Weight
Sensor and cable: 127 g (4.5 oz); with bracket: 290 g (10.2 oz)
Mote: 223 g (7.87 oz)
Materials
Sensor: PVC housing, epoxy potting compound, nylon grommet, FR-4
circuit board, PVC cable jacket
Bracket: PVC mounting bracket, UV-stable nylon cable ties, zinc
dichromate plated steel U-bolts
Mote: PCPBT, silicone rubber seal
RXW Leaf Wetness
Sensor
Models:
•RXW-LWA-900 (US)
•RXW-LWA-868 (Europe)
•RXW-LWA-921 (Taiwan)
•RXW-LWA-922
(Australia/NZ)
Included Items:
•Mounting bracket
•U-bolt
•Tie wraps

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
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Specifications (continued)
Environmental Rating
Sensor and cable: Weatherproof
Mote: IP67, NEMA 6
Compliance Marks
RXW-LWA-900: See last page
RXW-LWA-868: The CE Marking identifies this product as
complying with all relevant directives in the European Union
(EU).
RXW-LWA-921: See last page
RXW-LWA-922: See last page
Note 1 Given the nature of the sensor design and sensor operating frequency, the system has inherent susceptibilities
to Radio Frequency signals. The repeatability specification when subjected to certain RFI environments, such
as those outlined in IEC 61000-4-3 and IEC 61000-4-6, may be significantly reduced.
The system level repeatability will be particularly affected when placed in an electric field of 3 V/m or greater
in the 150 KHz to 1000 MHz range. RFI mitigation practices and physical deployment changes may reduce the
system susceptibility. If deployments are planned in high RFI energy environments, Onset recommends on-site
testing to determine system level repeatability.
Mote Components and Operation
Sensor Mote Closed, Front Sensor Mote Closed, Back
Sensor Mote Opened
Mounting Tab: Use the tabs at the top and bottom of the mote
to mount it (see Deploying and Mounting).
Solar Panel: Position the solar panel towards the sun to charge
the mote batteries (see Deploying and Mounting).
Sensor Cable: This is the cable that connects the mote to the
sensor.
Eyelet: Use this eyelet to attach a 3/16 inch padlock to the
mote for security.
Latch: Use the two latches to open and close the mote door.
Ground Wire Port: Use this port to connect a ground wire (see
Deploying and Mounting).
Antenna: This is the built-in antenna for the radio
communications across the HOBOnet Wireless Sensor Network.
LEDs: There are two LEDs to the left of the LCD screen. The
green LED blinks during the process of joining a network,
blinking quickly while the mote searches for a network and
then slowly as the mote registers with the network. Once the
network registration process is complete, the blue LED blinks at
4 seconds to indicate normal operation. If the mote is not
currently part of a network, the blue LED will be off. If the blue
LED is on and not blinking, there is a problem with the mote.
Contact Onset Technical Support.
Solar Panel Cable: This cable connects the built-in solar panel
to the mote circuitry.
Battery Holder: The location where the batteries are installed
as shown (see Battery Information).
USB Port: Use this port to connect to the mote to a computer
via USB cable if you need to update the firmware (see Updating
Mote Firmware).
Button: Push this button for 1 second to illuminate the LCD or 3
seconds for the mote to search for a HOBOnet Wireless Sensor
Network to join (see Adding the Mote to the HOBOnet Wireless
Sensor Network).
LCD Screen:The mote is equipped with an LCD screen that
displays details about the current status. This example shows all
symbols illuminated on the LCD screen followed by definitions
of each symbol in the table.
LCD Symbol
Description
The battery indicator shows the approximate battery
charge remaining.
Button
Solar Panel
USB Port
Latch
Battery Holder
LCD Screen
Mounting
Tab
Eyelet
Solar Panel Cable
Antenna
LEDs
Ground Wire
Port
Sensor Cable

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
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LCD Symbol
Description
This is a signal strength indicator. The more bars, the
stronger the signal between motes. If there is no x
icon next to the signal strength indicator, then the
mote is part of a HOBOnet Wireless Sensor Network.
An empty signal strength icon plus the x icon
indicates that the mote is not currently part of a
network. See Adding the Mote to the HOBOnet
Wireless Sensor Network for details on how to add a
mote to the network.
When the mote is in the process of joining a
network, the signal strength icon will blink and then
the bars in the icon will cycle from left to right. The x
icon will blink during the last step in the network
registration process (see Adding the Mote to the
HOBOnet Wireless Sensor Network for details).
This indicates a problem with the sensor itself (the
mote is operational). Check the sensor and make any
adjustments to it as needed. Contact Onset
Technical Support if the problem persists.
Adding the Mote to the HOBOnet Wireless
Sensor Network
The mote must join a HOBOnet Wireless Sensor Network
before it can begin measuring temperature and transmitting
data. This requires accessing the station and the mote at the
same time so it is recommended that you complete these steps
before deploying the mote.
Important: If you are setting up a new station, follow the
instructions in the station quick start before setting up this
mote (go to www.onsetcomp.com/support/manuals/24380-
man-rx2105-rx2106-qsg for RX2105 and RX2106 stations or go
to www.onsetcomp.com/support/manuals/18254-MAN-QSG-
RX3000 for RX3000 stations).
To add a mote to the network:
1. If the LCD is blank on the station, press any button to wake
it up.
2. Press the Select button once (which shows the number of
smart sensors installed) and then press it again to switch to
the module with the manager (module 2 on RX2105 or
RX2106 stations).
3. Press the Search button (the magnifying glass). The
magnifying glass icon will blink while the station is in search
mode.
4. Open the mote door and install the batteries if you have not
already done so.
5. Press the button on the mote for 3 seconds. The signal
strength icon will flash and then cycle.
6. Watch the LCD on the mote.
This process may take up to five minutes. The green LED
blinks quickly while the mote searches for a network to join
and then blinks slowly while it completes the network
registration. Once the mote has finished joining the
network, the green LED turns off and the blue LED then
blinks indefinitely while the mote is part of the network.
Note: If the mote cannot find the network or has trouble
remaining connected during this process, make sure the
mote is in a vertical, upright position and within range of
the station.
Press this button to view the module
Press this button for 3
seconds for the mote to
join the network
Press this button so the station is ready
to have motes join the network
This signal strength icon
blinks while searching for
a network.
Once a network is found,
the icon will stop flashing
and the bars will cycle from
left to right.
c.
d.
This network connection
“x” icon blinks while the
mote completes the
registration process.
which may take up to
five minutes.
Once the mote has finished joining
the network, the “x” icon is
removed and the channel count
on the station LCD increases by
two (one for leaf wetness and one
for the mote battery).
a.
b.

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
1-800-LOGGERS 4 www.onsetcomp.com
7. Press the Search button (the magnifying glass) on the
station to stop searching for motes.
If you added more than one more mote to the network, then
the total channel count on the station LCD for the manager
module will represent all measurement channels plus a battery
channel for each mote in the network.
Sensor measurements will be recorded at the logging interval
specified in HOBOlink, transmitted to the station, and uploaded
to HOBOlink at the next connection interval (readout). Use
HOBOlink to monitor mote status and health. If a mote is
temporarily offline, any logged data is saved until it is back
online. In addition, if a mote is offline for 30 minutes, the
station will automatically connect to HOBOlink and report the
mote as missing. Once the mote is back online, any logged data
will be uploaded the next time the station connects to
HOBOlink.
See the HOBOlink Help for details on how to change the logging
and connection intervals, view data, check mote status, add the
mote to a map, and more.
Deployment and Mounting
Mounting and Positioning the Mote
•Mount the mote to a mast or pipe using cable ties or affix
the mote to a wooden post or flat surface with screws.
Insert the cable ties or screws through the holes on the
mounting tabs.
•Consider using plastic poles such as PVC to mount the
mote as certain types of metal could decrease signal
strength.
•Make sure the mote remains in a vertical position once it
is placed in its deployment location for optimal network
communications.
•Make sure the mote door is closed, with both latches fully
locked to ensure a watertight seal.
•Consider using a 3/16 inch padlock to restrict access to the
mote. With the mote door closed, hook a padlock through
the eyelet on the right side of the door and lock it.
•Position the mote towards the sun, making sure the solar
panel is oriented so that it receives optimal sunlight
throughout each season. It may be necessary to
periodically adjust the mote position as the path of the
sunlight changes throughout the year or if tree and leaf
growth alters the amount of sunlight reaching the solar
panel.
•Make sure the mote is mounted a minimum of 1.8 m (6 ft)
from the ground or vegetation to help maximize distance
and signal strength.
•Place the mote so there is full line of sight with the next
mote. If there is an obstruction between two sensor
motes or between the sensor mote and the manager, then
use a repeater mounted on the obstruction. For example,
if there is a hill between the sensor mote and the
manager, place a repeater at the top of the hill between
the sensor mote and the manager.
•There should not be more than five motes in any direction
at their maximum transmission range from the manager.
Data logged by a wireless sensor must travel or “hop”
across the wireless network from one mote to the next
until it ultimately reaches the manager connected to the
station. To make sure the data can successfully travel
across the network, the mote should not be more than
five hops away from the manager.
•The HOBOnet Wireless Sensor Network can support a
maximum of 50 motes.
•Use a #4-40 screw to attach a ground wire to the port on
the back of the mote if you are deploying the mote in a
location where lightning is a concern.
Sensor Mounting Guidelines
Important: DO NOT PAINT OR COAT THE SENSOR. It is ready
to use and should not be coated. See Sensor Operation for
more details.
•In most applications, the sensor should be mounted in
whichever direction will prolong wetness the longest. For
example, in the Northern hemisphere, orienting the
sensor to face northwest will minimize exposure to solar
radiation in the morning and maximize morning dew
exposure.
•The leaf wetness sensor can be tilted to any angle. As the
angle becomes steeper, water will run off the sensor more
easily, reducing the amount of time the sensor stays wet.
The exact angle used is a function of the type of
vegetation of interest. Use an angle of more than 15
degrees from horizontal to prevent puddles from forming
on the sensor.
•The leaf wetness bracket can also be mounted to the cross
arm (M-CAA or M-CAB).
•Be sure to secure the sensor cable with cable ties to
protect the cable from damage. Wires should be bound
tightly to the mast to help protect them from getting
damaged in severe weather.
•Do not mount the sensor within two feet of the station
case.
•Refer to the station manual and Tripod Setup Guide at
www.onsetcomp.com/support/manuals for more
information regarding setting up stations.
Bracket Mounting
To mount the sensor using the included bracket:
1. Use the U-bolt to secure the bracket to any 2.5 to 4 cm (1 to
1.6 inch) diameter mast.
Press this button again to
stop searching for motes

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
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2. Use two cable ties to secure the sensor to the bracket. Do
not fully tighten the cable ties.
3. Note that one side of the sensor surface has a visible grid.
The grid side should be facing upwards. Typically the sensor
is mounted at an angle of 15 to 45 degrees from horizontal.
4. Once the desired angle has been set, pull the cable ties tight
and cut off the tag ends.
5. Secure the sensor cable with cable ties.
Sensor Operation
The leaf wetness sensor measures the percentage of the sensor
grid that is wet. A completely dry sensor will record 0%
wetness, while a measurement of 100% wetness corresponds
to the sensor being completely covered with a thin layer of
water.
After prolonged exposure to very hot and wet environments,
the sensor may return to only 1 to 3% wet when dried out, but
given a day or two in a warm, dry environment, the sensor will
recover and return to zero when dry.
IMPORTANT: Do Not Paint the Sensor.
Unlike most other leaf wetness sensors, the leaf wetness sensor
is ready to use and should not be coated. Some manufacturers
of leaf wetness sensors recommend painting their sensors with
a flat latex paint to improve the sensor’s characteristics. These
manufacturers supply their sensors uncoated and require the
user to paint it.
Do not coat the HOBO leaf wetness smart sensor. Onset’s
sensor is preconditioned and factory calibrated. Although it is
certainly possible to alter the response of the sensor by
painting it, applying any sort of coating will only reduce its
sensitivity.
Calibration
The leaf wetness sensor should be field calibrated to determine
the wet/dry transition point. Various types of vegetation will
have varying transition points. The best practice is to install a
station and the leaf wetness sensor in the study area and, while
logging data, directly observe the plants to record the time of
day that the vegetation makes the transition from wet to dry.
Export the logged station data to determine the percent
wetness when the wet/dry transition was observed. In most
cases, this is the value that will best represent the wet/dry
transition point for your study. You will need to retain this
value for use with any third-party software.
Maintenance
The sensor is a capacitive sensor and is less sensitive to
contamination than resistive sensors. However, dust, dirt or
other contaminants on the sensor will retain moisture and that
will ultimately affect the sensor’s performance. You should
periodically inspect the sensor and gently clean the sensor grid
once per year with a non-abrasive rag, mild soap, and fresh
water.
The mote is designed for outdoor use, but should be inspected
periodically. When inspecting the mote, do the following:
•Verify the mote is free of visible damage or cracks.
•Make sure the mote is clean. Wipe off any dust or grime
with a damp cloth.
•Wipe off any water before opening the mote.
•Make sure the interior seal is intact and the latches are
fully locked when the mote door is closed.
Verifying Sensor Accuracy
It is recommended that you check the accuracy of the leaf
wetness sensor annually. If the sensor is not providing accurate
data, it may be damaged or broken.
Updating Mote Firmware
If a new firmware version is available for the mote, use
HOBOlink to download the file to your computer.
1. In HOBOlink, go to Devices, RX Devices, and click your
station name.
2. On the station page, click Overview and scroll down to
Device Information.
3. Click the Wireless tab. This icon appears next to the
mote if there is a new version of firmware available.
4. Click the firmware upgrade link. Click Download and
save the firmware .bin file to your computer.
5. Connect the mote to the computer with a USB cable (open
the mote door and use the USB port to the right of the
LCD). The blue LED is illuminated while connected.
6. The mote appears as a new storage device in the
computer’s file storage manager. Copy the downloaded
firmware file to the new storage device (the mote). The
blue LED will blink slowly while the file is copying.
7. After the file is copied to the mote, the LED will stop
blinking and remain a steady blue. Eject the storage device
from the computer and disconnect the cable from the
mote. The firmware installation process will begin
automatically on the mote. The blue LED will blink rapidly
while the firmware is installed. Once the firmware
installation is complete, the LCD symbols return and the
mote will automatically rejoin the network.
Notes:
•Mac® users: A message may appear indicating the disk
has not ejected properly when disconnecting the mote
from the computer. The mote is operational and you can
ignore the message.
•If the blue LED turns off abruptly while copying the file or
installing the firmware, a problem has occurred. Contact
Onset Technical Support for help.
Battery Information
The mote uses two 1.2 V rechargeable NiMH batteries, charged
by the built-in solar panel. The quality and quantity of solar
light can affect whether the battery is sufficiently charged to

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
1-800-LOGGERS 6 www.onsetcomp.com
last through the night and cloudy periods. Make sure the mote
is placed in a location that will receive several hours of sunlight
each day. If the mote does not receive enough sunlight to
recharge the batteries, the battery life is estimated at 3–4
months. When batteries are regularly recharged, expected
battery life is estimated at 3–5 years. Battery life varies based
on the ambient temperature where the mote is deployed, the
logging interval, the number of tripped alarms, and other
factors. Deployments in extremely cold or hot temperatures
can impact battery life. Estimates are not guaranteed due to
uncertainties in initial battery conditions and operating
environment.
Mote operation will stop when battery voltage drops to 1.8 V.
Mote operation will return if the battery recharges to 2.3 V. If
the batteries are unable to be recharged, replace them with
fresh rechargeable batteries. Note: if you install used
rechargeable batteries that together are less than 2.3 V, the
mote will not resume operation.
To replace rechargeable batteries:
1. Open the mote door.
2. Remove the old batteries and install fresh ones observing
polarity.
3. Make sure the solar panel cable is plugged in.
The mote contacts the network once the new batteries are
installed. The green LED blinks during this process while the
bars in the signal strength indicator on the LCD cycle from left
to right and then the x icon blinks. Once this process is
complete, the x icon is removed, the green LED stops blinking,
and the blue LED begins blinking instead.
Lithium Batteries
You can use two 1.5 V lithium batteries (HWSB-LI) for operation
at the extreme ends of the mote operating range. Lithium
battery life is an estimated at 1 year, but varies based on the
ambient temperature where the mote is deployed, the logging
interval, the number of tripped alarms, and other factors.
Estimates are not guaranteed due to uncertainties in initial
battery conditions and operating environment. When using
lithium batteries, you must disconnect the solar panel cable
because the batteries will not be recharged.
To install lithium batteries:
1. Open the mote door.
2. Remove any old batteries and install the new ones
observing polarity.
3. Push in the side tab of the solar panel cable connector and
pull the connector out of the cable port.
4. Place the connector in the slot on the inside of the mote
door. Make sure the solar panel cables are tucked inside the
door so that they do not interfere with the interior seal
when the mote is closed.
The mote contacts the network once the new batteries are
installed. The green LED blinks quickly while the mote searches
for a network to join and then blinks slowly while it completes
the network registration. Once the mote has finished joining
the network, the green LED turns off and the blue LED then
blinks indefinitely while the mote is part of the network.
WARNING: Do not cut open, incinerate, heat above 85°C
(185°F), or recharge the lithium batteries. The batteries may
explode if the mote is exposed to extreme heat or conditions
that could damage or destroy the battery cases. Do not mix
battery types, either by chemistry or age; batteries may rupture
or explode. Do not dispose of the logger or batteries in fire. Do
not expose the contents of the batteries to water. Dispose of
the batteries according to local regulations for lithium
batteries.
Store the solar
panel connector
here when using
lithium batteries
Make sure
solar panel
cable is
installed
when using
rechargeable
batteries

RXW Leaf Wetness Sensor (RXW-LWA-xxx) Manual
1
-800-LOGGERS (564-4377) • 508-759-9500
www.onsetcomp.com
/support/contact
© 2019–2020 Onset Computer Corporation. All rights reserved. Onset, HOBO, HOBOlink, and HOBOnet are
registered trademarks of Onset Computer Corporation. Mac is a registered trademark of Apple Inc. All other
trademarks are the property of their respective companies.
23962-C
Federal Communication Commission Interference Statement
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference in a residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user
is encouraged to try to correct the interference by one of the following measures:
•Reorient or relocate the receiving antenna
•Increase the separation between the equipment and receiver
•Connect the equipment into an outlet on a circuit different from that to which the receiver is connected
•Consult the dealer or an experienced radio/TV technician for help
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device
must accept any interference received, including interference that may cause undesired operation.
FCC Caution: Any changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate this equipment.
Industry Canada Statements
This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the following two conditions: (1) this device may not cause interference, and
(2) this device must accept any interference, including interference that may cause undesired operation of the device.
Avis de conformité pour l’Industrie Canada
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de licence. L'exploitation est autorisée aux deux conditions suivantes : (1)
l'appareil ne doit pas produire de brouillage, et (2) l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d'en compromettre le
fonctionnement.
To comply with FCC and Industry Canada RF radiation exposure limits for general population, the logger must be installed to provide a separation distance of at least 20cm from
all persons and must not be co-located or operating in conjunction with any other antenna or transmitter.
NCC Statement
經型式認證合格之低功率射頻電機，非經許可，公司、商號或使用者均不得擅自變更頻率、加大功率或變更原設計之特性及功能。
低功率射頻電機之使用不得影響飛航安全及干擾合法通信；經發現有干擾現象時，應立即停用，並改善至無干擾時方得繼續使用。前項合法通信，指依電信法規定作
業之無線電通信。低功率射頻電機須忍受合法通信或工業、科學及醫療用電波輻射性電機設備之干擾。
Translation:
Article 12
Without permission granted by the NCC, any company, enterprise, or user is not allowed to change frequency, enhance transmitting power or alter original characteristic as well
as performance to an approved low power radio-frequency device.
Article 14
The low power radio-frequency devices shall not influence aircraft security and interfere with legal communications. If found, the user shall cease operating immediately until no
interference is achieved. The said legal communications means radio communications is operated in compliance with the Telecommunications Act. The low power radio-
frequency devices must be susceptible with the interference from legal communications or ISM radio wave radiated devices.