Vaisala WMT50 User Manual

USER'S GUIDE

®

Vaisala WINDCAP

Ultrasonic Wind Sensor WMT50

M210736EN-B

PUBLISHED BY

Vaisala Oyj Phone (int.): [phone]

P.O. Box 26 Fax: [phone]

FIN-00421 Helsinki

Finland

Visit our Internet pages at http://www.vaisala.com/

© Vaisala 2006

No part of this manual may be reproduced in any form or by any means,
electronic or mechanical (including photocopying), nor may its contents
be communicated to a third party without prior written permission of the
copyright holder.

The contents are subject to change without prior notice.

Please observe that this manual does not create any legally binding
obligations for Vaisala towards the customer or end user. All legally
binding commitments and agreements are included exclusively in the
applicable supply contract or Conditions of Sale.

________________________________________________________________________________

Table of Contents

CHAPTER 1

GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Contents of This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

General Safety Considerations . . . . . . . . . . . . . . . . . . . . . 10

ESD Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

License Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

CHAPTER 2

PRODUCT OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Introduction to Ultrasonic Wind Sensor WMT50 . . . . . . . . 15

Optional Software for Easy Settings . . . . . . . . . . . . . . . . . 16

Heating Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Ultrasonic Wind Sensor WMT50 Components . . . . . . . . . . 17

CHAPTER 3

FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Wind Measurement Principle . . . . . . . . . . . . . . . . . . . . . . . . 21

Heating (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

CHAPTER 4

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Unpacking Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Selecting Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Installation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Mounting to Vertical Pole Mast . . . . . . . . . . . . . . . . . . 26

Mounting with Optional Mounting Kit . . . . . . . . . . . . . . 27

Mounting To Horizontal Cross Arm . . . . . . . . . . . . . . . 28

Aligning WMT50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Compass Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Wind Direction Correction . . . . . . . . . . . . . . . . . . . . . . 30

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CHAPTER 5

WIRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Operating Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Heating Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Wiring Using the Screw Terminals . . . . . . . . . . . . . . . . . . .35

Wiring Using the 8-pin M12 Connector (Optional) . . . . . . .37

External Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Data Communication Interfaces . . . . . . . . . . . . . . . . . . . . .39

CHAPTER 6

COMMUNICATION SETTINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Communication Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Service Cable Connection . . . . . . . . . . . . . . . . . . . . . . . . . .42

Connection Through M12 Bottom Connector or Screw

Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Communication Setting Commands . . . . . . . . . . . . . . . . . .44

Checking the Current Communication Settings (aXU) . . . .44

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Changing the Communication Settings . . . . . . . . . . . . . . .47

CHAPTER 7

GETTING THE DATA MESSAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

General Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Reset (aXZ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Measurement Reset (aXZM) . . . . . . . . . . . . . . . . . . . . . . .50

ASCII Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Abbreviations and Units . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Device Address (?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . .52

Supervisor Data Message (aR5) . . . . . . . . . . . . . . . . . . . .53

Combined Data Message (aR) . . . . . . . . . . . . . . . . . . . . . .54

Composite Data Message Query (aR0) . . . . . . . . . . . . . . . 54

Polling with CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Automatic Composite Data Message . . . . . . . . . . . . . . . . .57

SDI-12 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Address Query Command (?) . . . . . . . . . . . . . . . . . . . . . . 59

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . .60

Change Address Command (aAb) . . . . . . . . . . . . . . . . . . . 61

Send Identification Command (aI) . . . . . . . . . . . . . . . . . . .61

Start Measurement Command (aM) . . . . . . . . . . . . . . . . . .62

Start Measurement Command with CRC (aMC) . . . . . . . .64

Start Concurrent Measurement (aC) . . . . . . . . . . . . . . . . .64

Start Concurrent Measurement with CRC (aCC) . . . . . . . .65

Send Data Command (aD) . . . . . . . . . . . . . . . . . . . . . . . . .65

Examples of aM, aC and aD Commands . . . . . . . . . . . . . .67

Continuous Measurement (aR) . . . . . . . . . . . . . . . . . . . . . 68

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Continuous Measurement with CRC (aRC) . . . . . . . . . . . . 69

Start Verification Command (aV) . . . . . . . . . . . . . . . . . . . . 69

NMEA 0183 V3.0 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Device Address (?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . . 71

MWV Wind Speed and Direction Query . . . . . . . . . . . . . . . 71

XDR Transducer Measurement Query . . . . . . . . . . . . . . . 73

TXT Text Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Automatic Composite Data Message . . . . . . . . . . . . . . . . . 79

CHAPTER 8

SENSOR AND DATA MESSAGE SETTINGS . . . . . . . . . . . . . . . . . . . . . . 81

Wind Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Checking the Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Changing the Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Supervisor Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Checking the Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Changing the Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Composite Data Message . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

CHAPTER 9

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Factory Calibration and Repair Service . . . . . . . . . . . . . . . 92

Vaisala Service Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Parts List for Consumables . . . . . . . . . . . . . . . . . . . . . . . . . 92

CHAPTER 10

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Self-Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Error Messaging/Text Messages . . . . . . . . . . . . . . . . . . . . 95

Wind Sensor Heating Control . . . . . . . . . . . . . . . . . . . . . . 97

Operating Voltage Control . . . . . . . . . . . . . . . . . . . . . . . . . 97

Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

CHAPTER 11

TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

APPENDIX A

NETWORKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Connecting Several WMT50s on the Same Bus . . . . . . . . 105

SDI-12 Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

VAISALA ________________________________________________________________________ 3

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Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

Communication Protocol . . . . . . . . . . . . . . . . . . . . . . . . .106

RS-485 Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Communication Protocol . . . . . . . . . . . . . . . . . . . . . . . . .107

ASCII, Polled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

NMEA 0183 v3.0, Query . . . . . . . . . . . . . . . . . . . . . . . . .107

NMEA 0183 v3.0 Query with ASCII Query Commands . .110

APPENDIX B

SDI-12 PROTOCOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113

SDI-12 Electrical Interface . . . . . . . . . . . . . . . . . . . . . . . . .113

SDI-12 Communications Protocol . . . . . . . . . . . . . . . . . .113

SDI-12 Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

APPENDIX C

CRC-16 COMPUTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Encoding the CRC as ASCII Characters . . . . . . . . . . . . . .118

NMEA 0183 v3.0 Checksum Computation . . . . . . . . . . . .118

APPENDIX D

WIND MEASUREMENT AVERAGING METHOD . . . . . . . . . . . . . . . . . . .119

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List of Figures

Figure 1 Ultrasonic Wind Sensor WMT50 . . . . . . . . . . . . . . . . . . . . . . .15

Figure 2 WMT50 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 3 Sensor Bottom Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 4 Mounting Kit (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 5 Service Cable (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 6 Location of Fixing Screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Figure 7 Mounting WMT50 to Pole Mast Using Optional Mounting Kit . 28

Figure 8 Mounting WMT50 to Cross Arm. . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 9 Mounting Screw Location in Cross Arm . . . . . . . . . . . . . . . . . . 29

Figure 10 Sketch of Magnetic Declination . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 11 Wind Direction Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 12 Average Operational Current Consumption (with 4Hz Wind

Sensor Sampling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 13 Heating Current and Power Against Vh . . . . . . . . . . . . . . . . . . 35

Figure 14 Screw Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 15 Pins of 8-pin M12 Connector . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 16 Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 17 Data Communication Interfaces. . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 18 WMT50 Dimensions in mm [inches]. . . . . . . . . . . . . . . . . . . . 102

Figure 19 Mounting Kit Dimensions in mm [inches] . . . . . . . . . . . . . . . . 103

Figure 20 Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Figure 21 Wind Measurement Averaging Method . . . . . . . . . . . . . . . . . 120

VAISALA ________________________________________________________________________ 5

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6 _______________________________________________________________________________

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List of Tables

Table 1 Screw Terminal Pin-outs for WMT50 Serial Interfaces and

Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table 2 Pin-outs for WMT50 Serial Interfaces and Power Supplies . . . . .37

Table 3 Available Serial Communication Protocols . . . . . . . . . . . . . . . . . 41

Table 4 Default Serial Communication Settings for M12/Screw Terminal

Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Table 5 Abbreviations and Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Table 6 Transducer IDs of the Measurement Parameters . . . . . . . . . . . . 75

Table 7 Transducer Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Table 8 Available Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Table 9 Data Validation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Table 10 Communication Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Table 11 Error Messaging/Text Messages Table . . . . . . . . . . . . . . . . . . . . 96

Table 12 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Table 13 Inputs and Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Table 14 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Table 15 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Table 16 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Table 17 Options and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

VAISALA ________________________________________________________________________ 7

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8 _______________________________________________________________________________

Chapter 1 ________________________________________________________ General Information

CHAPTER 1

GENERAL INFORMATION

This chapter provides general notes for the product.

About This Manual

This manual provides information for installing, operating, and

maintaining the product.

Contents of This Manual

This manual consists of the following chapters:

- Chapter 1, General Information: This chapter provides general
notes for the product.

- Chapter 2, Product Overview: This chapter introduces the unique
features and advantages of the Vaisala Ultrasonic Wind Sensor
WMT50.

- Chapter 3, Functional Description: This chapter describes the
measurement principles and heating function of Ultrasonic Wind
Sensor WMT50.

- Chapter 4, Installation: This chapter provides you with information
that is intended to help you install Ultrasonic Wind Sensor
WMT50.

- Chapter 5, Wiring: This chapter provides you with instructions on
how to connect the power supply and the serial interfaces.

VAISALA ________________________________________________________________________ 9

User’s Guide ______________________________________________________________________

- Chapter 6, Communication Settings: This chapter contains the
instructions for making the communication settings.

- Chapter 7, Getting the Data Messages: This chapter presents the
general and data message commands.

- Chapter 8, Sensor and Data Message Settings: This chapter
presents the sensor configuration and data message formatting
commands for all communications protocols: ASCII, NMEA 0183
and SDI-12.

- Chapter 9, Maintenance: This chapter contains instructions for the
basic maintenance of Ultrasonic Wind Sensor WMT50 and contact
information for Vaisala Service Centers.

- Chapter 10, Troubleshooting: This chapter describes common
problems, their probable causes and remedies, and includes contact
information for technical support.

- Chapter 11, Technical Specifications: This chapter provides the
technical data of Ultrasonic Wind Sensor WMT50.

Safety

WARNING

Feedback

Vaisala Customer Documentation Team welcomes your comments and
suggestions on the quality and usefulness of this publication. If you find
errors or have other suggestions for improvement, please indicate the
chapter, section, and page number. You can send comments to us by e­mail: [e-mail].

General Safety Considerations

Throughout the manual, important safety considerations are highlighted
as follows:

Warning alerts you to a serious hazard. If you do not read and follow
instructions very carefully at this point, there is a risk of injury or even
death.

10 ___________________________________________________________________M210736EN-B

Chapter 1 ________________________________________________________ General Information

CAUTION

NOTE

Caution warns you of a potential hazard. If you do not read and follow
instructions carefully at this point, the product could be damaged or
important data could be lost.

Note highlights important information on using the product.

ESD Protection

Electrostatic Discharge (ESD) can cause immediate or latent damage to
electronic circuits. Vaisala products are adequately protected against
ESD for their intended use. However, it is possible to damage the
product by delivering electrostatic discharges when touching,
removing, or inserting any objects inside the equipment housing.

To make sure you are not delivering high static voltages yourself:

- Handle ESD sensitive components on a properly grounded and
protected ESD workbench. When this is not possible, ground
yourself with a wrist strap and a resistive connection cord to the
equipment chassis before touching the boards. When neither of the
above is possible, at least touch a conductive part of the equipment
chassis with your other hand before touching the boards.

Recycling

- Always hold the boards by the edges and avoid touching the
component contacts.

Recycle all applicable material.

Dispose of batteries and the unit according to statutory regulations.
Do not dispose of with regular household refuse.

VAISALA _______________________________________________________________________ 11

User’s Guide ______________________________________________________________________

Trademarks

WINDCAP® is a registered trademark of Vaisala. Microsoft®,
Windows®, Windows NT® and Windows XP® are registered

trademarks of Microsoft Corporation in the United States and/or other
countries.

License Agreement

All rights to any software are held by Vaisala or third parties. The
customer is allowed to use the software only to the extent that is
provided by the applicable supply contract or Software License
Agreement.

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Chapter 1 ________________________________________________________ General Information

Warranty

Vaisala hereby represents and warrants all Products
manufactured by Vaisala and sold hereunder to be free
from defects in workmanship or material during a
period of twelve (12) months from the date of delivery
save for products for which a special warranty is given.
If any Product proves however to be defective in
workmanship or material within the period herein
provided Vaisala undertakes to the exclusion of any
other remedy to repair or at its own option replace the
defective Product or part thereof free of charge and
otherwise on the same conditions as for the original
Product or part without extension to original warranty
time. Defective parts replaced in accordance with this
clause shall be placed at the disposal of Vaisala.

Vaisala also warrants the quality of all repair and
service works performed by its employees to products
sold by it. In case the repair or service works should
appear inadequate or faulty and should this cause
malfunction or nonfunction of the product to which the
service was performed Vaisala shall at its free option
either repair or have repaired or replace the product in
question. The working hours used by employees of
Vaisala for such repair or replacement shall be free of
charge to the client. This service warranty shall be
valid for a period of six (6) months from the date the
service measures were completed.

This warranty does not however apply when the defect
has been caused through

a) normal wear and tear or accident;

b) misuse or other unsuitable or unauthorized use of
the Product or negligence or error in storing,
maintaining or in handling the Product or any
equipment thereof;

c) wrong installation or assembly or failure to service
the Product or otherwise follow Vaisala's service
instructions including any repairs or installation or
assembly or service made by unauthorized personnel
not approved by Vaisala or replacements with parts not
manufactured or supplied by Vaisala;

d) modifications or changes of the Product as well as
any adding to it without Vaisala's prior authorization;

e) other factors depending on the Customer or a third
party.

Notwithstanding the aforesaid Vaisala's liability under
this clause shall not apply to any defects arising out of
materials, designs or instructions provided by the
Customer.

This warranty is however subject to following
conditions:

a) A substantiated written claim as to any alleged
defects shall have been received by Vaisala within
thirty (30) days after the defect or fault became known
or occurred, and

b) The allegedly defective Product or part shall, should
Vaisala so require, be sent to the works of Vaisala or to
such other place as Vaisala may indicate in writing,
freight and insurance prepaid and properly packed and
labelled, unless Vaisala agrees to inspect and repair the
Product or replace it on site.

This warranty is expressly in lieu of and excludes all
other conditions, warranties and liabilities, express or
implied, whether under law, statute or otherwise,
including without limitation any implied warranties of
merchantability or fitness for a particular purpose and
all other obligations and liabilities of Vaisala or its
representatives with respect to any defect or deficiency
applicable to or resulting directly or indirectly from the
Products supplied hereunder, which obligations and
liabilities are hereby expressly cancelled and waived.
Vaisala's liability shall under no circumstances exceed
the invoice price of any Product for which a warranty
claim is made, nor shall Vaisala in any circumstances
be liable for lost profits or other consequential loss
whether direct or indirect or for special damages.

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Chapter 2 __________________________________________________________ Product Overview

CHAPTER 2

PRODUCT OVERVIEW

This chapter introduces the unique features and advantages of the
Vaisala Ultrasonic Wind Sensor WMT50.

Introduction to Ultrasonic Wind Sensor WMT50

0601-016

Figure 1 Ultrasonic Wind Sensor WMT50

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User’s Guide ______________________________________________________________________

Ultrasonic Wind Sensor WMT50 is a small and lightweight wind sensor
that measures wind speed and direction.

WMT50 powers up with 5 ... 30 VDC and outputs serial data with a
selectable communication protocol: SDI-12, ASCII automatic & polled
and NMEA 0183 with query option. Four alternative serial interfaces
are selectable: RS-232, RS-485, RS-422 and SDI-12.

The following options are available:

- Heating function

- Windows® based Vaisala Configuration Tool software and cable

- 8-pin M12 connector (also with 2 m/10 m cable)

- Mounting kit

Optional Software for Easy Settings

Windows® based Vaisala Configuration Tool is a user friendly
parameter setting software for WMT50. With this software tool you can

change the device and sensor settings easily in Windows® environment.
See list of options and accessories in Table 17 on page 101.

Heating Function

To improve the accuracy of measurements an optional heating function
is available. More about heating in section Heating (Optional) on page

23.

The heating function option must be chosen when placing the order.

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Chapter 2 __________________________________________________________ Product Overview

Ultrasonic Wind Sensor WMT50 Components

0601-017

Figure 2 WMT50 Components

The following numbers refer to Figure 2 on page 17:

1 = Top assembly

2 = Silicon gasket

3 = Spacers

4 = Bottom assembly

5 = Allen screws

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0505-192

Figure 3 Sensor Bottom Assembly

The following numbers refer to Figure 3 on page 18:

1 = Alignment direction sign

2 = Service port

3 = Water tight cable gland (shown disassembled)

4 = Opening for cable gland (if unused, cover with hexagonal

plug)

5 = 8-pin M12 connector for power/datacom cable (optional,

cover with hexagonal plug if unused)

0505-193

Figure 4 Mounting Kit (Optional)

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Chapter 2 __________________________________________________________ Product Overview

0505-194

Figure 5 Service Cable (Optional)

The following numbers refer to Figure 5 on page 19:

1 = Battery connector

2 = D9-connector for PC serial port

3 = Connector for WMT50 service port (press the white flap

while disconnecting cable)

CAUTION

The service cable, while connected between the service port and PC,
forces the service port to RS-232 / 19200, 8, N, 1.

To prevent ingress of water, dust, and insects, cover the unused
openings at the sensor bottom assembly with hexagonal rubber plugs
included in the delivery.

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Chapter 3 ______________________________________________________ Functional Description

CHAPTER 3

FUNCTIONAL DESCRIPTION

This chapter describes the measurement principles and heating function
of Ultrasonic Wind Sensor WMT50.

Wind Measurement Principle

The WMT50 uses Vaisala WINDCAP® sensor technology in wind
measurement.

The wind sensor has an array of three equally spaced ultrasonic
transducers on a horizontal plane. Wind speed and wind directions are
determined by measuring the time it takes the ultrasound to travel from
each transducer to the other two.

The wind sensor measures the transit time (in both directions) along the
three paths established by the array of transducers. This transit time
depends on the wind speed along the ultrasonic path. For zero wind
speed, both the forward and reverse transit times are the same. With
wind along the sound path, the up-wind direction transit time increases
and the down-wind transit time decreases.

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The wind speed is calculated from the measured transit times using the
following formula:

V

0505-216

0.5 L 1 tf1 tre–euu=

w

where:

Vw = Wind speed

L = Distance between the two transducers

tf = Transit time in forward direction

tr = Transit time in reverse direction

Measuring the six transit times allows Vw to be computed for each of
the three ultrasonic paths. The computed wind speeds are independent
of altitude, temperature and humidity, which are cancelled out when the
transit times are measured in both directions, although the individual
transit times depend on these parameters.

Using Vw values of two array paths is enough to compute wind speed
and wind direction. A signal processing technique is used so that wind
speed and wind direction are calculated from the two array paths of best
quality.

The wind speed is represented as a scalar speed in selected units (m/s,
kt, mph, km/h). The wind direction is expressed in degrees (°). The
wind direction reported by WMT50 indicates the direction that the wind
comes from. North is represented as 0°, east as 90°, south as 180°, and
west as 270°.

The wind direction is not calculated when the wind speed drops below

0.05 m/s. In this case, the last calculated direction output remains until
the wind speed increases again to the level of 0.05 m/s.

The average values of wind speed and direction are calculated as a
scalar average of of all samples over the selected averaging time
[1 ... 3600 s (= 60 min)]. The sample count depends on the selected
sampling rate: 4 Hz (default), 2 Hz or 1 Hz. The minimum and
maximum values of wind speed and direction represent the
corresponding extremes during the selected averaging time. See also

Appendix D, Wind Measurement Averaging Method, on page 119 for

averaging method.

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Chapter 3 ______________________________________________________ Functional Description

Heating (Optional)

Heating elements located inside the wind transducers keep the wind
sensors clean from snow and ice. A heating temperature sensor (Th)
controls the heating.

Three fixed temperature limits, namely +10 °C, +4 °C, and -50 °C
(+50 °F, +39 °F, -58 °F) control the heating power as follows:

Th > +10 °C: heating is off,

+4 °C < Th < +10 °C: 50 % heating power,

-50 °C < Th < +4 °C: 100 % heating power,

Th < -50 °C: 50 % heating power.

When the heating function is disabled the heating is off in all conditions,
see Supervisor Message on page 86.

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Chapter 4 _______________________________________________________________ Installation

CHAPTER 4

INSTALLATION

This chapter provides you with information that is intended to help you
install Ultrasonic Wind Sensor WMT50.

Unpacking Instructions

Ultrasonic Wind Sensor WMT50 comes in a custom shipping container.
Be careful when removing the device from the container.

CAUTION

Beware of damaging any of the wind transducers located at the top of
the three antennas. Dropping the device can break or damage the
transducers. If the antenna bends or twists the re-aligning can be
difficult or impossible.

Selecting Location

Finding a suitable site for Ultrasonic Wind Sensor WMT50 is important
for getting representative ambient measurements. The site should
represent the general area of interest.

Ultrasonic Wind Sensor WMT50 needs to be installed in a location that
is free from turbulence caused by nearby objects, such as trees or
buildings.

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WARNING

To protect personnel (and the device), a lightning rod is recommended
to be installed with the tip at least one meter above the WMT50. The
rod must be properly grounded, compliant with all local applicable
safety regulations.

Installation Procedure

At the measurement site, WMT50 needs to be mounted, aligned, and
connected to the data logger and the power source.

Mounting

Ultrasonic Wind Sensor WMT50 can be mounted either onto a vertical
pole mast or onto a horizontal cross arm. When mounting WMT50 onto
a pole mast, an optional mounting kit can be used to ease mounting.
When using the optional mounting kit, alignment is needed only when
mounted for the first time.

NOTE

Each of the mounting options is further described in the following
sections.

Ultrasonic Wind Sensor WMT50 must be installed to an upright,
vertical position.

Mounting to Vertical Pole Mast

1. Remove the screw cover and insert the WMT50 to the pole mast.

2. Align the sensor in such a way that the arrow points to north.

3. Tighten the fixing screw (provided) and replace the screw cover.

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Chapter 4 _______________________________________________________________ Installation

0601-018

Figure 6 Location of Fixing Screw

Mounting with Optional Mounting Kit

1. Insert the mounting kit adapter to the sensor bottom in the position
shown in the picture.

2. Turn the kit inside the bottom firmly until you feel that the adapter
snaps into the locked position.

3. Mount the adapter to the pole mast, do not tighten the fixing screw
(provided).

4. Align the sensor in such a way that the arrow points to north.

5. Tighten the fixing screw to fix the adapter firmly to the pole mast.

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0601-019

Figure 7 Mounting WMT50 to Pole Mast Using Optional

Mounting Kit

NOTE

The following numbers refer to Figure 7 on page 28:

1 = Fixing screw

2 = Mounting kit

When removing the WMT50 from the pole just turn the sensor so that
it snaps out from the mounting kit. When replacing the device the
alignment is not needed.

Mounting To Horizontal Cross Arm

1. Remove the screw cover.

2. Align the horizontal cross arm in south-north-direction, see

Aligning WMT50 on page 29.In case the cross arm cannot be

aligned, make the wind direction correction as instructed in section

Wind Direction Correction on page 30.

3. Mount the sensor into the cross arm by using the fixing screw (M6
DIN933) and a nut, see Figure 7 on page 28 and Figure 8 on page

29.

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