THIES 4.3811.00.000 Operating Instructions Manual
THE WORLD OF WEATHER DATA - THE WORLD OF WEATHER DATA - THE WORLD OF WEATHER DATA
Ultrasonic Anemometer 2
D
4.3811.00.000
Software version V2.00 or higher Status: 10/2006
Operating Instructions
021511/10/06
ADOLF THIES GmbH & Co. KG
Hauptstraße 76 37083 Göttingen Germany
Box 3536 + 3541 37025 Göttingen
Phone ++551 79001-0 Fax ++551 79001-65
www.thiesclima.com info@thiesclima.com
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Contents
1 Application ................................................................................................................................. 4
2 Mode of Operation ..................................................................................................................... 4
2.1 Measuring principle: Wind velocity and direction ................................................................ 5
2.2 Measuring principle: Acoustic virtual temperature............................................................... 6
3 Preparation for Operation / Installation ...................................................................................... 6
3.1 Selection of installation site ................................................................................................. 7
3.2 Installation of anemometer .................................................................................................. 7
3.3 Alignment to north ............................................................................................................... 7
3.4 Cables, cable preparation, connector installation................................................................ 7
3.5 Connector pin assignment................................................................................................... 9
4 Maintenance .............................................................................................................................. 9
5 Calibration................................................................................................................................10
6 Warranty .................................................................................................................................. 10
7 Functional Description ............................................................................................................. 11
7.1 Serial communication ........................................................................................................ 11
7.1.1 General telegram structure ......................................................................................... 12
7.1.2 Return values of ULTRASONIC.................................................................................. 13
7.1.3 Access mode .............................................................................................................. 13
7.1.4 Device ID .................................................................................................................... 14
7.1.5 Bus mode.................................................................................................................... 14
7.2 Data acquisition................................................................................................................. 14
7.2.1 Averaging.................................................................................................................... 14
7.3 Serial data output .............................................................................................................. 15
7.3.1 Data enquiry ............................................................................................................... 15
7.3.2 Fixed telegram formats ............................................................................................... 15
00005 ............................................................................................................................................. 15
7.4 Generation of check sum .................................................................................................. 16
7.5 Status information ............................................................................................................. 16
7.5.1 Definition of status byte version 1............................................................................... 16
7.5.2 Structure of status byte version 1 ............................................................................... 16
7.5.3 Definition of temperature difference in status byte ..................................................... 17
7.5.4 Definition of averaging memory used ......................................................................... 17
7.6 Behaviour in fault conditions ............................................................................................. 17
7.7 Heating control .................................................................................................................. 17
7.8 Output of all system parameters ....................................................................................... 18
7.9 Enquiry about software version ......................................................................................... 18
7.10 Forcing a restart ................................................................................................................ 18
7.11 Bootloader ......................................................................................................................... 18
7.12 Online Help........................................................................................................................ 18
8 Configuration of Ultrasonic Anemometer by Customer............................................................ 19
9 Command List, Short ............................................................................................................... 20
10 Predefined Data Telegram.................................................................................................... 22
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11 Technical Data...................................................................................................................... 23
12 Dimension Drawing .............................................................................................................. 25
13 Accessories (available as optional features) ........................................................................ 25
Fig.
Fig. 1: Connector assembly.............................................................................................................. 8
Table
Table 1: Return values with incorrect interpretation of command .................................................. 13
Table 2: Access key for different command levels ......................................................................... 13
Table 3: List of predefined data telegrams ..................................................................................... 15
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1 Application
The Ultrasonic Anemometer 2D is used to detect the horizontal components of wind velocity and
wind direction as well as the virtual temperature in 2 dimensions.
Due to the measuring principle the instrument is ideal for inertia-free measurement of gusts and
peak values.
The level of accuracy achieved when measuring the air temperature (virtual temperature)
surpasses that of classical methods, in which the temperature sensors are used with weather and
radiation protection, following correction of the influence of damp occurring with certain weather
situations.
Output of the measured values is digital. An RS485 in half duplex mode is available for serial
communication.
Serial output of the data is as a sliding mean.
The sensor arms are automatically heated if necessary with critical ambient temperatures. This also
ensures functionality with snowfall and sleet and minimises the risk of malfunctions due to icing-up.
The model No. 4.3811.00.000 has additional protection from mechanical stresses such as ice
fracture and attack by birds by means of metal encapsulated ultrasonic transformers.
These Operating Instructions relate to the device version 4.3811.00.000. They describe possible
applications and settings.
The Ultrasonic Anemometer 2D is factory-set. Identification for the factory setting is via the order
No. and "Factory Setting".
Order number and setting
see supplementary sheet "Factory Setting"
In addition, the default settings for device version 4.3811.00.000 are marked in "grey" in these
Operating Instructions.
2 Mode of Operation
The Ultrasonic Anemometer 2D consists of 4 ultrasonic transformers, in pairs of two facing each
other at a distance of 200 mm. The two resulting measurement paths are vertical to each other.
The transformers function both as acoustic transmitters and receivers.
The electronic control system is used to select the respective measurement path and its measuring
direction. When a measurement starts, a sequence of 4 individual measurements is performed in
all 4 directions of the measurement paths at maximum speed.
The measuring directions (sound propagation directions) rotate clockwise, first from south to north,
then from west to east, from north to south and finally from east to west.
The mean values are worked out from the 4 individual measurements of the path directions and
used to make further calculations..
The time required for a measuring sequence is approx. 2.5 msec at +20°C at the maximum
measuring speed.
2.1 Measuring principle: Wind velocity and direction
The speed of propagation of the sound in calm air is superposed by the velocity components of an
air flow in the direction of the wind.
A wind velocity component in the propagation direction of the sound supports the speed of
propagation; i.e. it increases it while a wind velocity component against the propagation direction
reduces the speed of propagation.
The propagation speed resulting from superposition leads to different propagation times of the
sound at different wind velocities and directions over a fixed measurement path.
As the speed of sound greatly depends on the temperature of the air, the propagation time of the
sound is measured on each of the two measurement paths in both directions. This rules out the
influence of temperature on the measurement result.
By combining the two measurement paths which are at right angles to each other, the
measurement results of the sum and the angle of the wind velocity vector are obtained in the form
of perpendicular components.
After the perpendicular velocity components have been measured, they are then converted to polar
coordinates by the µ processor of the anemometer and output as a sum and angle of wind velocity.
Wind from NNE
Y-component
X-component
E
N
W
S
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2.2 Measuring principle: Acoustic virtual temperature
The speed of propagation of the sound depends on the absolute temperature of the air via a root
function although it is more or less independent of the air pressure and only depends on the air
humidity to a minor extent. We can thus make use of these physical properties for temperature
measurement of air with a known and constant chemical composition.
Here we measure gas temperature without the indirect step of thermal coupling involving this gas to
a sensor.
The advantages of this measuring method are firstly an inertia-free reaction to the actual gas
temperature, and secondly, the avoidance of measuring errors such as those that occur for
example when a solid-state temperature sensor is heated by radiation.
Due to the low dependence of the speed of propagation of the sound on the air humidity level the
"acoustic virtual temperature" relates to dry air (0% humidity) under the same pressure conditions
as those actually measured.
The deviation of the measured "acoustic virtual temperature" from the real air temperature shows
linear dependence on the absolute humidity level of the air.
The amount of water vapour in the air proportionately increases the speed of the sound as H
2
O
molecules only have around half the mass of the other air molecules (O
2
and N2).
The increase in the speed of the sound results in an apparent (virtual) increase in the measured
temperature of humid air in comparison to dry air of the same temperature.
The deviation of the measured virtual temperature of humid air from the real air temperature can be
corrected for instance according to the following relationship if the absolute humidity is known:
T
r
= Tv – 0.135 K * m3 / g * a
where T
r
is the real air temperature, Tv the measured acoustic virtual temperature and a the
absolute humidity in grammes H
2
O per m3 air.
With an air temperature of 20°C the virtual temperature is around 2 K too high with 100% rel.
humidity.
3 Preparation for Operation / Installation
Attention:
The working position of the anemometer is vertical (sensor
arms "above", connector "below").
During installation, de-installation, transport or maintenance of
the anemometer it must be ensured that no water gets into the
shaft or connector of the anemometer.
When using a lightning rod it must be borne in mind that it
should always be installed less than 45° to a measurement
path; otherwise there will be deviations in the measured values.
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3.1 Selection of installation site
As already described, the ultrasonic anemometer transmits sound packages required to measure
the propagation speed. If these sound packages meet surfaces that reflect sound, they are thrown
back as an echo and can may result in incorrect measurements under unfavourable conditions.
It is therefore advisable to install the ultrasonic anemometer at a minimum distance of 1 metre to
objects in the measuring level.
In general, wind meters should register wind conditions over a wide area. To obtain comparable
values when measuring the ground wind, measurement should be performed at a height of 10
metres above even and undisrupted terrain. Undisrupted terrain means that the distance between
the wind transmitter and the obstruction should be at least ten times the height of the obstruction (s.
VDI 3786). If it is not possible to comply with this provision, the wind meter should be installed at a
height at which measured values are influenced by obstructions located in the vicinity to the least
possible extent (approx. 6-10 m above the interference level). On flat roofs the anemometer should
be installed in the middle of the roof and not at the edge to thus avoid any preferential directions.
3.2 Installation of anemometer
Proper installation of the ultrasonic anemometer is carried out using a tube socket R1½" (Ø 48.3
mm) and 50 mm in length The inside diameter of the tube socket must be at least 40 mm as the
ultrasonic anemometer is electrically connected to the connector (s. Accessories: connecting cable,
compl.) from below. After connection the ultrasonic anemometer is fitted on the tube or mast
socket. The arm of the sonic transformer marked red must be aligned to north. This allows a
bearing to be taken from an object located to the north, e.g. a building or special geographical
feature, using the sonic transformers of the north / south measurement path.
The instrument is fixed to the shaft with the four Allen screws (AF 4 mm).
3.3 Alignment to north
To align the anemometer, the arm of the sonic transformer marked red must point to north
(true north). To do so, select a conspicuous feature of the landscape to the north or south with a
compass and turn the mast or anemometer until the opposing arms are aligned in this direction.
The user can also position himself to the north or south at an appropriate distance while another
person turns the anemometer or mast as commanded until the relevant pair of sensor arms are
aligned.
It is recommended using a telescope for this process.
When aligning the instrument to north using a compass, the magnetic variation (= deviation in
direction of compass needle from true north) and local magnetic fields (e.g. iron parts, electric
cables) should be taken into account.
3.4 Cables, cable preparation, connector installation
A prepared connecting cable can be supplied for the ultrasonic anemometer (see Accessories).
If the user wants to procure the cable himself, the cable must have the following properties:
8 cores; 0.5 to 0.75 mm² core cross-section for supply; min. 0.14 mm² core cross-section for data
communications ; max. 8 mm cable diameter, resistant to ultraviolet rays, overall shielding.
The coupling socket (mating connector) is included in the scope of supply. This is placed in the
bottom of the box for shipment.
The pin assignment can be found in these Operating Instructions: see under 3.5 pin assignment.
The cable shield should be connected with the cable clamp.
Coupling socket 507550 (Binder, series 432), EMC with cable clamp
View X
Cable strain relief
Cable assembly 1
1. String parts onto cable according to
diagram above.
2. Strip off cable sheath 20 mm
Shorten exposed shield by 15 mm
Strip off litz wire 5mm.
Cable assembly 1
Fit shrink tube or insulating tape
between litz wire and shield.
Cable assembly 2
Position shield to rear on
cable sheath if cable diameter
permits.
3. Solder litz wire to female insert,
position shield in cable clamp.
4. Screw on cable clamp.
5. Assemble other parts according to
diagram above.
6. Securely tighten cable strain relief
with spanner (AF16 and 17).
Cable assembly 2
View X
View X
Fig. 1: Connector assembly
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