Vaisala WMT52 User Manual

USER'S GUIDE

®

Vaisala WINDCAP

Ultrasonic Wind Sensor WMT52

M210925EN-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 2012

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

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

Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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

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

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

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

Regulatory Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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

CHAPTER 2

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

Introduction to Ultrasonic Wind Sensor WMT52 . . . . . . . . 15

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

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

Ultrasonic Wind Sensor WMT52 Components . . . . . . . . . . 17

CHAPTER 3

FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Wind Measurement Principle . . . . . . . . . . . . . . . . . . . . . . . . 23

Heating (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

CHAPTER 4

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Unpacking Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Selecting the Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Installation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Mounting to Vertical Pole Mast . . . . . . . . . . . . . . . . . . 30

Mounting with Optional Mounting Kit . . . . . . . . . . . . . . 31

Mounting To Horizontal Cross Arm . . . . . . . . . . . . . . . 32

Grounding the WMT52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Grounding using the Bushing and Grounding Kit. . . . . 34

Marine Grounding Jumper . . . . . . . . . . . . . . . . . . . . . . 35

Aligning the WMT52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Compass Alignment. . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Wind Direction Offset . . . . . . . . . . . . . . . . . . . . . . . . . . 37

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CHAPTER 5

WIRING AND POWER MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Operating Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Heating Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Wiring Using the 8-pin M12 Connector . . . . . . . . . . . . . . . .42

External Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Wiring Using the Screw Terminals . . . . . . . . . . . . . . . . . . .44

Data Communication Interfaces . . . . . . . . . . . . . . . . . . . . .46

Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

CHAPTER 6

CONNECTION OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Communication Protocols . . . . . . . . . . . . . . . . . . . . . . . . . .51

Connection cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Installing the Driver for the USB Cable . . . . . . . . . . . . . . .53

Service Cable Connection . . . . . . . . . . . . . . . . . . . . . . . . . .54

Connection Through M12 Bottom Connector

or Screw Terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Communication Setting Commands . . . . . . . . . . . . . . . . . .56

Checking the Current Communication Settings (aXU) . . . .56

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Changing the Communication Settings (aXU) . . . . . . . . . .59

CHAPTER 7

GETTING THE DATA MESSAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

General Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Reset (aXZ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Measurement Reset (aXZM) . . . . . . . . . . . . . . . . . . . . . . .63

ASCII Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Abbreviations and Units . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Device Address (?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . .65

Wind Data Message (aR1) . . . . . . . . . . . . . . . . . . . . . . . . .66

Supervisor Data Message (aR5) . . . . . . . . . . . . . . . . . . . . 67

Combined Data Message (aR) . . . . . . . . . . . . . . . . . . . . . .68

Composite Data Message Query (aR0) . . . . . . . . . . . . . . .68

Polling with CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Automatic Composite Data Message (aR0) . . . . . . . . . . . .71

SDI-12 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Address Query Command (?) . . . . . . . . . . . . . . . . . . . . . .72

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . .73

Change Address Command (aAb) . . . . . . . . . . . . . . . . . . .73

Send Identification Command (aI) . . . . . . . . . . . . . . . . . . .74

Start Measurement Command (aM) . . . . . . . . . . . . . . . . . .75

Start Measurement Command with CRC (aMC) . . . . . . . .76

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Start Concurrent Measurement (aC) . . . . . . . . . . . . . . . . . 76

Start Concurrent Measurement with CRC (aCC) . . . . . . . . 77

Send Data Command (aD) . . . . . . . . . . . . . . . . . . . . . . . .78

Examples of aM, aC and aD Commands . . . . . . . . . . . . . . 79

Continuous Measurement (aR) . . . . . . . . . . . . . . . . . . . . . 80

Continuous Measurement with CRC (aRC) . . . . . . . . . . . . 81

Start Verification Command (aV) . . . . . . . . . . . . . . . . . . . .81

NMEA 0183 V3.0 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Device Address (?) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

Acknowledge Active Command (a) . . . . . . . . . . . . . . . . . . 83

MWV Wind Speed and Direction Query . . . . . . . . . . . . . . .83

XDR Transducer Measurement Query . . . . . . . . . . . . . . . 85

TXT Text Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . .91

Automatic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Automatic Composite Data Message (aR0) . . . . . . . . . . . .93

CHAPTER 8

SENSOR AND DATA MESSAGE SETTINGS . . . . . . . . . . . . . . . . . . . . . .95

Wind Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Checking the Settings (aWU) . . . . . . . . . . . . . . . . . . . . . . . 95

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Changing the Settings (aWU) . . . . . . . . . . . . . . . . . . . . . .99

Supervisor Message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Checking the Settings (aSU) . . . . . . . . . . . . . . . . . . . . . . 101

Setting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Changing the Settings (aSU) . . . . . . . . . . . . . . . . . . . . . . 103

Composite Data Message (aR0) . . . . . . . . . . . . . . . . . . . . .104

CHAPTER 9

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Factory Calibration and Repair Service . . . . . . . . . . . . . . 108

Vaisala Service Centers . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

CHAPTER 10

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

Self-Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Error Messaging/Text Messages . . . . . . . . . . . . . . . . . . . 111

Wind Sensor Heating Control . . . . . . . . . . . . . . . . . . . . . 113

Operating Voltage Control . . . . . . . . . . . . . . . . . . . . . . . . 113

Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

CHAPTER 11

TECHNICAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115

Options and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

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APPENDIX A

NETWORKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Connecting Several WMT52s on the Same Bus . . . . . . . .121

SDI-12 Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121

Communication Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 122

RS-485 Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122

Communication Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 123

ASCII, Polled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

NMEA 0183 v3.0, Query . . . . . . . . . . . . . . . . . . . . . . . . .124

NMEA 0183 v3.0 Query with ASCII Query Commands . .126

APPENDIX B

SDI-12 PROTOCOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

SDI-12 Electrical Interface . . . . . . . . . . . . . . . . . . . . . . . . .129

SDI-12 Communications Protocol . . . . . . . . . . . . . . . . . .130

SDI-12 Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131

APPENDIX C

CRC-16 COMPUTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

Encoding the CRC as ASCII Characters . . . . . . . . . . . . . .134

NMEA 0183 v3.0 Checksum Computation . . . . . . . . . . . .134

APPENDIX D

WIND MEASUREMENT AVERAGING METHOD . . . . . . . . . . . . . . . . . . .135

APPENDIX E

FACTORY CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

General Unit Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138

Wind Configuration Settings . . . . . . . . . . . . . . . . . . . . . . .138

Supervisor Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

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List of Figures

Figure 1 Ultrasonic Wind Sensor WMT52 . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 2 WMT52 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Figure 3 Bottom of the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Figure 4 Mounting Kit (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Figure 5 USB Cables (optional). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 6 Bird Spike Kit (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 7 Surge Protector (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 8 Heating Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 9 Recommended Mast Location in an Open Area . . . . . . . . . . . 28

Figure 10 Recommended Mast Length on Top of a Building. . . . . . . . . . 29

Figure 11 Location of Fixing Screw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 12 Mounting WMT52 to Pole Mast Using Optional Mounting Kit .32

Figure 13 Mounting WMT52 to Cross Arm. . . . . . . . . . . . . . . . . . . . . . . .33

Figure 14 Mounting Bolt Location in Cross Arm. . . . . . . . . . . . . . . . . . . .33

Figure 15 Grounding Using the Bushing and Grounding Kit . . . . . . . . . . 34

Figure 16 Grounding Jumper Location. . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 17 Sketch of Magnetic Declination . . . . . . . . . . . . . . . . . . . . . . . .36

Figure 18 Wind Direction Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 19 Average Operational Current Consumption (with 4Hz

Wind Sensor Sampling) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 20 Heating Current and Power vs Vh . . . . . . . . . . . . . . . . . . . . . . 41

Figure 21 Pins of 8-pin M12 Connector . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 22 Internal Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Figure 23 Screw Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Figure 24 Data Communication Interfaces. . . . . . . . . . . . . . . . . . . . . . . . 46

Figure 25 WMT52 Dimensions in mm (inch) . . . . . . . . . . . . . . . . . . . . . 119

Figure 26 Mounting Kit Dimensions in mm (inch). . . . . . . . . . . . . . . . . .120

Figure 27 SDI-12 Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Figure 28 Wind Measurement Averaging Method . . . . . . . . . . . . . . . . .136

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List of Tables

Table 1 Pin-outs for WMT52 Serial Interfaces and Power Supplies . . . . . 42

Table 2 Screw Terminal Pin-outs for WMT52 Serial Interfaces and

Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 3 Available Serial Communication Protocols . . . . . . . . . . . . . . . . . 51

Table 4 Connection Cable Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Table 5 Default Serial Communication Settings for M12/Screw

Terminal Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Table 6 Abbreviations and Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Table 7 Transducer IDs of the Measurement Parameters . . . . . . . . . . . . 87

Table 8 Transducer Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Table 9 Data Validation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

Table 10 Communication Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Table 11 Error Messaging/Text Messages Table . . . . . . . . . . . . . . . . . . . . 112

Table 12 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Table 13 Inputs and Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

Table 14 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

Table 15 Electromagnetic Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Table 16 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Table 17 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117

Table 18 Options and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Table 19 General Unit Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Table 20 Wind Configuration Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Table 21 General Unit Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

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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
WMT52.

- Chapter 3, Functional Description: This chapter describes the
measurement principles and heating function of Ultrasonic Wind
Sensor WMT52.

- Chapter 4, Installation: This chapter provides you with information
that is intended to help you install Ultrasonic Wind Sensor
WMT52.

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

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User’s Guide ______________________________________________________________________

serial interfaces, and how to manage and estimate the average
power consumption.

- Chapter 6, Connection options: This chapter contains instructions
for configuring the communication with the sensor.

- 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 WMT52 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.

WARNING

CAUTION

NOTE

- Chapter 11, Technical Specifications: This chapter provides the
technical data of Ultrasonic Wind Sensor WMT52.

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.

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.

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Chapter 1 ________________________________________________________ General Information

Recycle all applicable material.

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

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].

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.

Recycling

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.

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

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User’s Guide ______________________________________________________________________

Trademarks

WINDCAP® is a registered trademark of Vaisala. Microsoft®,
Windows®, Windows 2000®, Windows XP®, Windows Server 2003®,
and Windows Vista® 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.

Regulatory Compliance

The electromagnetic compatibility of the WMT52 has been tested
according to the following product family standard:

IEC 61326-1 Electrical equipment for measurement, control and
laboratory use - EMC requirements - for use in industrial locations.

Additionally, the EMC specification and vibration tolerance of the
WMT52 has been enhanced for marine use according to the following
sections of the IEC 60945 Maritime Navigation and
Radiocommunication Equipment and Systems - General requirements ­Methods of testing and required test results:

- IEC 60945 / 61000-4-4 (EFT burst)

- IEC 60945 / 61000-4-2 (Marine ESD)

- IEC 60945, paragraph 8, vibration

A summary of the EMC test results is presented in Table 15 on page

117.

The WMT52 is in conformance with the provisions of the RoHS
directive of the European Union:

Directive on the Restriction of the Use of Certain Hazardous Substances
in Electrical and Electronic Equipment (2002/95/EC)

12 ___________________________________________________________________M210925EN-B

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.

VAISALA_______________________________________________________________________ 13

User’s Guide ______________________________________________________________________

14 ___________________________________________________________________M210925EN-B

Chapter 2 __________________________________________________________ Product Overview

CHAPTER 2

PRODUCT OVERVIEW

This chapter introduces the unique features and advantages of the
Vaisala Ultrasonic Wind Sensor WMT52.

Introduction to Ultrasonic Wind Sensor WMT52

0806-009

Figure 1 Ultrasonic Wind Sensor WMT52

VAISALA_______________________________________________________________________ 15

User’s Guide ______________________________________________________________________

Ultrasonic Wind Sensor WMT52 is a small and lightweight wind sensor
that measures wind speed and direction. The sensor housing is IP65/
IP66 rated.

WMT52 powers up with 5 ... 32 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

- Service Pack 2: Windows® based Vaisala Configuration Tool
software with USB service cable (1.4m)

- USB RS-232/RS-485 cable (1.4m)

- Mounting kit

- Bird spike kit

- Surge protector

- Shielded cables (2m, 10m, 40m)

- Bushing and grounding kit

Heating Function

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

25.

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

Optional Software for Easy Settings

Windows® based Vaisala Configuration Tool is a user friendly
parameter setting software for WMT52. With this software tool you can

change the device and sensor settings easily in Windows® environment.
See list of options and accessories in Table 18 on page 118.

16 ___________________________________________________________________M210925EN-B

Chapter 2 __________________________________________________________ Product Overview

Ultrasonic Wind Sensor WMT52 Components

0803-041

Figure 2 WMT52 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

VAISALA_______________________________________________________________________ 17

User’s Guide ______________________________________________________________________

0803-029

Figure 3 Bottom of the Sensor

The following numbers refer to Figure 3 on page 18:

1 = Alignment direction sign

2 = 4-pin M8 connector for Service Port

3 = Water tight cable gland (optional, included in the Bushing and

Grounding Kit)

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

plug)

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

18 ___________________________________________________________________M210925EN-B

Chapter 2 __________________________________________________________ Product Overview

0505-193

Figure 4 Mounting Kit (Optional)

The optional mounting kit can be used to ease the mounting of the
WMT52 on a pole mast. When using the optional mounting kit,
alignment is needed only when mounting for the first time. Using the
mounting kit also improves the IP classification of the WMT52 to IP66.
Without the mounting kit, the WMT52 is IP65.

0804-022

Figure 5 USB Cables (optional)

The following numbers refer to Figure 5 on page 19:

1 = USB RS-232/RS-485 cable with 8-pin M12 threaded

connector (1.4 m)

2 = USB service cable with 4-pin M8 snap-on connector (1.4 m)

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

VAISALA_______________________________________________________________________ 19

User’s Guide ______________________________________________________________________

0804-007

Figure 6 Bird Spike Kit (optional)

The optional Bird Spike Kit for WXT transmitters and WMT sensors is
designed to reduce the interference that birds cause to the wind and rain
measurement. The kit consists of a metallic band with spikes pointing
upward. The kit is installed on top of the sensor, and attached with a
screw. The shape and location of the spikes has been designed so that
the interference with wind and rain measurement is minimal.

The spikes are designed not to hurt the birds; they are simply a barrier
to make it more difficult for birds to land on top of the sensor. Note that
the bird spike kit does not provide complete protection against birds, but
it does render the sensor unsuitable for roosting and nest building.

Note that when the kit is in place, more snow can accumulate on the
sensor, and the snow may melt slower.

20 ___________________________________________________________________M210925EN-B

Chapter 2 __________________________________________________________ Product Overview

0806-001

Figure 7 Surge Protector (optional)

The following surge protectors are available from Vaisala:

- Vaisala Surge Protector WSP150 is a compact transient
overvoltage suppressor designed for outdoor use. It can be used
with all Vaisala wind and weather instruments. The WSP150
should be installed close to the protected instrument (max 3 m).

- Vaisala Surge Protector WSP152 is designed to be used with
Vaisala WXT transmitters and WMT sensors, to protect the host
PC against surges entering through the USB port. The WSP152
should be installed close to the PC, no further than the USB cable
can reach (1.4 m).

Vaisala recommends using surge protectors when weather instruments
are installed on top of high buildings or masts and in open grounds, that
is, anywhere with an elevated risk of lightning strike. Also use the surge
protectors if your cable length exceeds 30 m or you have unshielded,
open-wire lines.

VAISALA_______________________________________________________________________ 21

User’s Guide ______________________________________________________________________

22 ___________________________________________________________________M210925EN-B

Chapter 3 ______________________________________________________ Functional Description

CHAPTER 3

FUNCTIONAL DESCRIPTION

This chapter describes the measurement principles and heating function
of Ultrasonic Wind Sensor WMT52.

Wind Measurement Principle

The WMT52 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.

VAISALA_______________________________________________________________________ 23

User’s Guide ______________________________________________________________________

V

w

0.5 L 1 tf1 tre–euu=

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

0505-216

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 WMT52 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) with a selectable updating interval. 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 135.

24 ___________________________________________________________________M210925EN-B

Chapter 3 ______________________________________________________ Functional Description

Depending on user selection the wind speed extreme values can be
computed in two alternative ways; either with the traditional minimum/
maximum calculation or with the 3-second gust & lull calculation
recommended by the WMO (World Meteorological Organization). In
the latter case the highest and lowest 3-second average values (updated
once a second) replace the maximum and minimum values in reporting
of wind speed, while the wind direction variance is returned in the
traditional way.

The WMT52 constantly monitors the wind measurement signal quality.
If poor quality is detected, the wind values are marked as invalid. If over
half of the measurement values can be considered as invalid, the last
valid wind values are returned as missing data. However, in the SDI-12
protocol the invalid values will be marked as zeroes.

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. Th is measured inside the sensor, where
temperature is much higher than the ambient temperature (Ta).

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

0806-010

Figure 8 Heating Control

VAISALA_______________________________________________________________________ 25

User’s Guide ______________________________________________________________________

The following example shows how heating behaves as Ta starts to fall:

- When Ta falls below +10 °C, heating is enabled.

- Heating keeps Th > +4 °C until Ta < -11 °C.

- Between -11 ... -65 °C, Th is approximately 15 °C warmer
than Ta.

When the heating function is disabled the heating is off in all conditions,
see Supervisor Message on page 101.

NOTE

Snow accumulation may cause a temporary wind measurement
problem even when the heating is enabled.

26 ___________________________________________________________________M210925EN-B

Chapter 4 _______________________________________________________________ Installation

CHAPTER 4

INSTALLATION

This chapter provides you with information that is intended to help you
install Ultrasonic Wind Sensor WMT52.

Unpacking Instructions

Ultrasonic Wind Sensor WMT52 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.

VAISALA_______________________________________________________________________ 27

User’s Guide ______________________________________________________________________

Selecting the Location

Finding a suitable site for WMT52 is important for getting
representative ambient measurements. The site should represent the
general area of interest.

The WMT52 should be installed in a location that is free from
turbulence caused by nearby objects, such as trees and buildings. In
general, any object of height (h) will not remarkably disturb wind
measurement at a minimum distance of 10 h. There should be at least
150 m open area in all directions from the mast. Refer to Figure 9 on

page 28.

0806-004

Figure 9 Recommended Mast Location in an Open Area

28 ___________________________________________________________________M210925EN-B