HOBO S-WDA Wind Direction Smart Sensor Datasheet

HOBO S-WDA Wind Direction Smart Sensor Datasheet
Wind Direction Smart Sensor (S-WDA-M003) Manual
The Wind Direction smart sensor is designed to work with HOBO® stations. The smart sensor
has a plug-in modular connector that allows it to be added easily to a HOBO station. All sensor
parameters are stored inside the smart sensor, which automatically communicates
configuration information to the logger without the need for any programming or extensive
Wind Direction
Smart Sensor
Item included:
• Mounting rod
• Full cross arm (M-CAA)
• Half cross arm (M-CAB)
Measurement Range
0 to 355 degrees, 5 degree dead band
±5 degrees
1.4 degrees
Starting Threshold
1 m/s (2.2 mph)
Maximum Wind Speed Survival
67 m/s (150 mph)
Measurement Definition
Unit vector averaging used; vector components for each wind
measurement are calculated every three seconds for duration of
logging interval (see Measurement Operation)
Operating Temperature Range
-40°C to 70°C (-40°F to 158°F)
Environmental Rating
Service Life
4 to 6 years typical depending upon environmental conditions
Injection-molded plastic housing and vane, static dissipating base,
lead-free silicon bronze nose and aluminum mounting rod
Bearing Type
Two shielded stainless steel ball bearing
Turning Radius
Approximately 13.5 cm (5.25 in.)
46 x 20 cm (18 x 8.5 in.) including 1.27 cm (0.5 in) diameter mounting
rod; 2.5 mm (0.1 in.) drip overhang
370 g (13 oz)
Bits per Sample
Number of Data Channels*
Measurement Averaging Option
Automatic averaging (see Measurement Operation)
Cable Length Available
3.5 m (11.5 ft)
Length of Smart Sensor
Network Cable*
0.5 m (1.6 ft)
The CE Marking identifies this product as complying with all relevant
directives in the European Union (EU).
* A single HOBO station can accommodate 15 data channels and up to 100 m (328 ft) of smart sensor cable (the digital
communications portion of the sensor cables).
15290-D MAN-SWDA
Wind Direction Smart Sensor (S-WDA-M003) Manual
4. Adjust the height of the sensor in the cross arm as
necessary using one of the following methods and then
tighten the nut and bolt until the cross arm just starts to
Placement and Mounting Considerations
• The Wind Direction smart sensor should be mounted
vertically in a location free of wind shadows.
a. Loosen the tri-clamp bolts and raise or lower the entire
mast so the sensor is close to the desired height. Make
sure there is at least 5 cm (2 inches) of mast extending
below the lower tri-clamp.
• For accurate wind direction measurements, mount the
sensor at a distance of at least five times the height of the
nearest tree, building, or other obstruction.
b. Make sure the upper mast dimple is still facing north (if
in northern hemisphere) and then re-tighten the triclamps. Once the tri-clamp bolts are tight, tighten the
lock nuts to lock the bolts in place. This requires two
wrenches: one to hold the bolt and one to tighten the
lock nut against the tri-clamp.
• Be sure to secure the sensor cable with cable ties to
protect it from damage.
• The tripod or mounting mast must be properly grounded.
For field installations, you can use Onset’s Grounding Kit
c. Loosen the bolt holding the sensor mounting rod and
raise or lower it as necessary to the desired height. Retighten the bolt.
• Secure the mast the wind sensor is mounted on so that it
does not vibrate. If you are using Onset masts or tripods,
secure them with guy wires.
5. Use cable ties to secure the sensor cables to the cross arm,
bracket, and mast. The sensor cables should run below the
cross arm and brackets to minimize the chance of birds
pecking and damaging the cables. Cable ties should be
spaced no more than 0.3 m (1 foot) apart. Make sure there
are drip loops on both sides of the smart sensor housing,
which must also be mounted horizontally, as described
under Placement and Mounting Considerations.
• The sensor can be damaged with improper handling. Store
the sensor in its shipping box until you are ready to install
• To minimize measurement errors due to ambient RF, use
the shortest possible probe cable length and keep the
probe cable as far as possible from other cables carrying
high frequency or high-current signals.
• To provide long-term protection from moisture entry, the
smart sensor adapter must be mounted horizontally and
with the cable wires routed with drip loops so that water
drains away from the cable entry point as shown in the
example below. When mounted properly, the housing is
weatherproof (but not waterproof).
Mounting rod
Cable ties
Sensor cable
Drip loop
• Refer to the Tripod Setup Guide for more information.
Mounting the Sensor to a Tripod Cross Arm
1. Insert a 1/4-20 x 1 3/4 inch hex head bolt with a flat washer
on it through the 1/4 inch hole on the end of the cross arm.
Install a lock washer and nut on the bolt. Tighten with a
7/16 inch wrench until snug.
Mounting the Sensor to a Pole
1. Loosely secure the sensor with two hose clamps (not
included). Adjust the height as necessary, but make sure the
hose clamps are separated by at least 4 inches (10 cm).
2. Insert the sensor mounting rod into the cross arm allowing
the mounting rod to protrude 1.3 cm (1/2 inch) from the
bottom of the cross arm.
3. Tighten the nut and bolt until the rod is slightly clamped in
Wind Direction Smart Sensor (S-WDA-M003) Manual
2. Secure the sensor cable with cable ties. Make sure there are
drip loops on both sides of the smart sensor housing, which
must also be mounted horizontally, as described under
Placement and Mounting Considerations.
North markings
Hose clamps
Mounting rod
2. Secure the base and vane shaft with a piece of tape so that
the vane cannot rotate.
Cable ties around
sensor cable
3. While standing 150 to 200 feet south of the sensor, use the
compass to determine magnetic north. If true north is the
same as magnetic north, align yourself so the compass
points north and directly at the sensor. If you are in area
with an east variation, align yourself so that the station is
that number of degrees to the east of magnetic north. If
you are in an area with a west variation, align yourself so
that the station is that number of degrees to the west of
magnetic north.
4. While viewing the sensor through binoculars, instruct
another person to rotate the sensor mounting rod to point
the vane north. The vane should seem to disappear from
sight when properly aligned.
3. Tighten the hose clamps making sure the mounting rod
remains vertical.
5. Once you’ve obtained the correct position, secure the
mounting rod and remove the tape.
4. Follow the steps in the North Alignment section.
North Alignment
GPS Alignment
The wind direction sensor must be oriented properly to obtain
meaningful data. This involves aligning the north markings on
the base of the sensor with true north. There are two methods
to align the sensor:
Compass Alignment
Global Positioning Satellite (GPS) alignment.
Tools required:
Compass Alignment
Tape (such as electrical, packing, or duct tape)
Flag, orange cone, or other temporary marker
Laptop computer with logger software installed
2. Connect the laptop to the logger with the PC interface cable.
3. Pick a visible location that is at least 100 meters (110 yards)
away from the wind direction sensor and walk to it.
Establish a waypoint with the handheld GPS receiver. You
may want to use averaging to minimize the waypoint
position error if your GPS receiver is so equipped. (For best
results, the estimated position error of the waypoint should
be less than 10 feet if the distance to the sensor is 100
meters, and less than 20 feet for a distance of 200 meters.
Mark the waypoint with a flag, orange cone, or other
suitable marker.
Two people are required to complete this procedure.
1. Align bronze tip of the wind vane with the north markings
on the base.
1. Connect the sensor to the logger (refer to the Connecting to
the Logger section below).
Tools required:
Handheld GPS with WAAS-enabled receiver or any
similar high accuracy GPS device
This procedure requires only one person, but is easier to
complete with two people. In this procedure, you will be using
the GPS receiver first to create an arbitrary waypoint and then
to determine the bearing from the sensor to that waypoint. You
will then align the sensor so that when the vane is pointed at
the waypoint, the direction reported by the logger software
matches the GPS receiver’s bearing to the waypoint.
Note: The magnetic declination must be known to align the
direction sensor to true north using a magnetic compass.
Worldwide declination information is available from the
National Space Science Data Center at:
Wind Direction Smart Sensor (S-WDA-M003) Manual
4. Walk back to the sensor and determine the bearing to the
waypoint you just created with the GPS receiver. Again you
may need to determine the average value of the bearing to
keep the errors to a minimum.
5. Start the logger software and select Status to get the
current reading (refer to the software manual or online help
for details about operating the software).
6. Point the sensor vane directly at the waypoint flag or
marker and rotate the sensor mounting rod until the wind
direction sensor value in the logger software matches the
angle obtained with the GPS receiver.
Verifying Sensor Accuracy
It is recommended that you check the accuracy of the sensor
annually. The wind direction sensor cannot be calibrated. Onset
uses precision components to obtain accurate measurements.
If the smart sensor is not providing accurate data, then it is
damaged or possibly worn out if it has been in use for several
years. If you are unsure of the accuracy, you can send the smart
sensor back to Onset for inspection and possible replacement
of the mechanism or bearings if required. Contact Onset or
your dealer for a Return Merchandise Authorization (RMA)
number before sending the sensor.
7. Once the vane is in position, secure the mounting rod and
then double-check that the reported angle is correct.
Connecting the Sensor to a Station
To connect the sensor to a station, stop the station from
logging and insert the smart sensor’s modular jack into an
available smart sensor port on the station. See the station
manual for details on operating stations with smart sensors.
Measurement Operation
Wind direction measurements are averaged over the logging
interval or a 3-second timeframe (whichever is greater). If you
set up the sensor to log faster than every 3 seconds, the same
sensor reading will be recorded until a new 3-second average is
calculated. For example, if the sensor is logging at a 1-second
interval, the sensor will report the same wind direction (its
calculated average) for three samples before calculating and
reporting a new value for another three samples.
Direction Averaging
Unit vector averaging is used to determine wind direction
because traditional averaging would produce inaccurate
results. For example, three measurements of 350, 11, and 12
degrees—which are all winds from the north—averaged
together would result in 126 degrees, which incorrectly
indicates a southeasterly wind. Instead, the vector components
(North/South and East/West) for each wind measurement are
calculated every three seconds for the duration of the logging
interval. At the conclusion of the logging interval, the
North/South and East/West components are averaged and
then re-combined to calculate the average wind direction for
the logging interval.
The sensor does not normally require any maintenance other
than an occasional cleaning. If the vane becomes dirty, rinse
the sensor with mild soap and fresh water. Do not immerse the
sensor in water or use any organic solvents to clean the unit.
1-800-LOGGERS (564-4377) • 508-759-9500
www.onsetcomp.com • [email protected]
© 2011–2015 Onset Computer Corporation. All rights reserved. Onset and HOBO are trademarks or
registered trademarks of Onset Computer Corporation. All other trademarks are the property of
their respective companies.
15290-D MAN-SWDA
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