Vaisala DRYCAP DMT340 SERIES User manual

USER'S GUIDE
Vaisala DRYCAP® Dewpoint and
Temperature Transmitter Series
DMT340
M210704EN-F

PUBLISHED BY
Vaisala Oyj Phone (int.): [phone]
P.O. Box 26 Fax: [phone]
FI-00421 Helsinki
Finland
Visit our Internet pages at http://www.vaisala.com/
© Vaisala 2011
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.

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Table of Contents
CHAPTER 1
GENERAL INFORMATION..........................................................................11
About This Manual.................................................................11
Contents of This Manual.....................................................11
Version Information.............................................................12
Documentation Conventions...............................................12
Safety.......................................................................................13
ESD Protection....................................................................13
Recycling ................................................................................13
Regulatory Compliances.......................................................14
EU Declaration of Conformity..............................................14
Transmitters with LAN or WLAN Interface..........................14
Transmitters with WLAN Interface ......................................15
Patent Notice ..........................................................................15
Trademarks.............................................................................15
License Agreement................................................................15
Warranty..................................................................................16
CHAPTER 2
PRODUCT OVERVIEW................................................................................17
Introduction to DMT340.........................................................17
Basic Features and Options................................................18
Structure of the Transmitter ................................................19
Probe Options .....................................................................21
CHAPTER 3
INSTALLATION............................................................................................23
Mounting the Housing ...........................................................23
Standard Mounting without Mounting Plate........................23
Wall Mounting with Wall Mounting Kit.................................24
Mounting with DIN Rail Installation Kit................................26
Pole Installation with Installation Kit for Pole or Pipeline ....27
Mounting the Rain Shield with Installation Kit.....................28
Panel Mounting Frame........................................................28
Wiring ......................................................................................30
Cable Bushings...................................................................30
Grounding the Cables.........................................................31
Transmitter Housing Grounding..........................................32
Signal and Power Supply Wiring.........................................32
Connections to a 24 VAC Power Supply ............................34
Probe Mounting......................................................................35
DMT342 Small-size Flanged Probe for Use with
Sampling Cell......................................................................35
DMT344 For High-pressure Applications............................37
DMT347 Small Pressure-tight Probe..................................39

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Pressure-Tight Swagelok Installation Kits for DMT347.......39
DMT348 For Pressurized Pipelines.....................................41
Tightening the Clasp Nut.....................................................43
Ball Valve Installation Kit for DMT348.................................45
Leak Screw Installation .......................................................47
Mounting the Probe Directly to the Process........................48
Sampling Cell for DMT348..................................................50
Optional Modules ...................................................................52
Power Supply Module .........................................................52
Installation......................................................................53
Warnings ........................................................................54
Galvanic Isolation for Output...............................................57
Installation......................................................................57
Third Analog Output ............................................................57
Installation and Wiring....................................................58
Alarm Relays.......................................................................59
Installation and Wiring....................................................59
Selecting the Activation State of the Relay....................59
RS-422/485 Interface ..........................................................61
Installation and Wiring....................................................62
LAN Interface.......................................................................65
WLAN Interface...................................................................66
Attaching the WLAN Antenna ........................................67
Data Logger Module............................................................68
8-Pin Connector...................................................................70
CHAPTER 4
OPERATION.................................................................................................71
Getting Started........................................................................71
Display/Keypad.......................................................................72
Basic Display.......................................................................72
Graphic History....................................................................73
Menus and Navigation.........................................................75
Changing the Language.................................................76
Rounding Setting............................................................76
Display Backlight Setting................................................76
Display Contrast Setting.................................................77
Keypad Lock (Keyguard)................................................77
Menu PIN Lock...............................................................77
Factory Settings...................................................................78
Display Alarms.....................................................................78
Configuring a Display Alarm...........................................79
MI70 Link Program for Data Handling ..................................81
Serial Line Communication...................................................82
User Port Connection..........................................................83
User Port Operating Modes............................................83
Service Port Connection......................................................84
Connection Cables.........................................................84
Installing the Driver for the USB Cable ..........................84
Using the Service Port....................................................85
LAN Communication..............................................................85
IP Configuration...................................................................86
Using Display/Keypad....................................................86
Using Serial Line............................................................88
Wireless LAN Configuration................................................89
Using Display/Keypad....................................................90

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Using Serial Line............................................................91
Communication Protocol.....................................................92
Web Configuration for LAN and WLAN...............................92
Terminal Program Settings .................................................93
Opening a Serial/USB Connection.................................94
Opening a Telnet Session (LAN/WLAN)........................95
List of Serial Commands.....................................................96
Getting the Measurement Message from Serial Line .........99
Starting Continuous Outputting......................................99
Stopping Continuous Outputting....................................99
Outputting Reading Once ..............................................99
Assign an Alias for the SEND Command ....................100
Communicating with a Transmitter in POLL Mode...........100
OPEN...........................................................................100
CLOSE.........................................................................100
Formatting Serial Line Message .......................................101
FTIME and FDATE.......................................................101
FST ..............................................................................102
General Settings...................................................................103
Changing the Quantities and Units...................................103
Using Display/Keypad..................................................103
Using Serial Line..........................................................104
FORM...........................................................................104
UNIT.............................................................................105
Pressure Compensation Setting .......................................106
Using Display/Keypad..................................................106
Using Buttons on the Motherboard..............................107
Using Serial Line..........................................................107
XPRES and PRES..................................................107
Date and Time...................................................................108
Using Display/Keypad..................................................108
Using Serial Line..........................................................109
Data Filtering.....................................................................109
FILT..............................................................................110
Device Information............................................................110
LIGHT...........................................................................112
HELP............................................................................112
ERRS...........................................................................113
VERS ...........................................................................113
Resetting the Transmitter Using Serial Line .....................113
RESET.........................................................................113
Locking Menu/Keypad Using Serial Line..........................114
LOCK ...........................................................................114
Serial Output Settings..........................................................115
Using Display/Keypad.......................................................115
Using Serial Line...............................................................116
SERI.............................................................................116
SMODE........................................................................117
ADDR...........................................................................117
INTV.............................................................................118
SDELAY.......................................................................118
ECHO...........................................................................119
Data Recording.....................................................................120
Selecting the Data Recording Quantities..........................120
DSEL............................................................................120
View Recorded Data.........................................................121
DIR...............................................................................121

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PLAY ............................................................................122
Deleting the Recorded Files..............................................123
UNDELETE..................................................................123
Analog Output Settings .......................................................123
Changing the Output Mode and Range ............................123
Analog Output Quantities..................................................125
AMODE/ASEL..............................................................126
Analog Output Tests..........................................................127
ITEST ...........................................................................127
Analog Output Fault Indication Setting..............................128
AERR............................................................................128
Operation of Relays..............................................................129
Quantity for Relay Output..................................................129
Measurement-Based Relay Output Modes.......................129
Relay Setpoints............................................................129
Hysteresis.....................................................................131
Relay Indicating Transmitter Error Status .........................131
Enabling/Disabling the Relays...........................................133
Operation of the Indication LEDs ......................................134
Setting the Relay Outputs .................................................134
RSEL............................................................................135
Testing the Operation of Relays........................................137
RTEST..........................................................................137
Sensor Functions .................................................................138
AutoCal..............................................................................138
Automatic AutoCal........................................................138
Manual AutoCal............................................................139
Sensor Purge.....................................................................139
Starting and Configuring Sensor Purge ............................140
Using Display/Keypad (Optional).................................140
Using Serial Line..........................................................141
PURGE....................................................................141
PUR.........................................................................141
Sensor Warming................................................................142
CHAPTER 5
MODBUS ....................................................................................................143
Overview of MODBUS Protocol Support............................143
Taking MODBUS into Use.................................................144
Enabling Serial MODBUS.....................................................145
Using Display/Keypad (Optional) ......................................145
Using Serial Line ...............................................................145
Enabling Ethernet MODBUS................................................147
Using Display/Keypad (Optional) ......................................147
Using Serial Line ...............................................................148
Diagnostic MODBUS Counters ...........................................150
Viewing Counters Using Display/Keypad..........................150
Viewing Counters Using Service Port ...............................150
Disabling MODBUS ..............................................................151

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CHAPTER 6
MAINTENANCE .........................................................................................153
Periodic Maintenance ..........................................................153
Cleaning............................................................................153
Changing the Probe Filter.................................................153
Calibration and Adjustment...............................................153
Error States.......................................................................154
Technical Support................................................................156
Product Returns...................................................................156
CHAPTER 7
CALIBRATION AND ADJUSTMENT.........................................................157
Calibration.............................................................................157
User Calibration and Adjustment ......................................157
Opening and Closing the Adjustment Mode .....................158
Adjustment Information.....................................................159
CTEXT and CDATE.....................................................159
Adjusting Dewpoint Td/f .......................................................160
Two-Point Relative Humidity Adjustment using
Display/Keypad.................................................................160
Two-Point Relative Humidity Adjustment using
Serial Line .........................................................................162
One-Point Dewpoint Adjustment using Display/Keypad...162
One-Point Dewpoint Adjustment using Serial Line...........164
Adjusting Temperature........................................................165
Adjusting Temperature using Display/Keypad..................165
Adjusting Temperature using Serial Line..........................166
CT ................................................................................166
Adjusting Analog Outputs...................................................167
Adjusting Analog Outputs using Display/Keypad..............167
Adjusting Analog Outputs using Serial Line......................168
ACAL............................................................................168
CHAPTER 8
TECHNICAL DATA....................................................................................169
Specifications.......................................................................169
Performance......................................................................169
Operating Environment.....................................................170
Inputs and Outputs............................................................170
Mechanics.........................................................................171
Probe Specifications .........................................................171
Technical Specifications of Optional Modules ..................172
Power Supply Module..................................................172
Analog Output Module.................................................172
Relay Module...............................................................172
RS-485 Module............................................................173
LAN Interface Module ..................................................173
WLAN Interface Module...............................................173
Data Logger Module ....................................................173
Options and Accessories....................................................174
Dimensions (mm/inch).........................................................176

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APPENDIX A
CALCULATION FORMULAS.....................................................................181
APPENDIX B
MODBUS REFERENCE.............................................................................185
Function Codes.....................................................................185
Register Map.........................................................................186
Data Encoding...................................................................186
32-Bit Floating Point Format ........................................186
16-Bit Integer Format ...................................................187
Measurement Data (Read-Only).......................................188
Status Registers (Read-Only) ...........................................189
Configuration Registers.....................................................189
Exception Status Outputs....................................................190
Diagnostic Sub-Functions...................................................191
Device Identification Objects ..............................................192
Exception Responses..........................................................192

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List of Figures
Figure 1 Transmitter Body......................................................................19
Figure 2 Inside the Transmitter...............................................................20
Figure 3 Probe Options ..........................................................................21
Figure 4 Standard Mounting...................................................................23
Figure 5 Mounting with Wall Mounting Kit..............................................24
Figure 6 Dimensions of the Plastic Mounting Plate (mm/inch)...............24
Figure 7 Mounting with Metal Wall Mounting Plate................................25
Figure 8 Dimensions of Metal Mounting Plate (mm/inch) ......................25
Figure 9 Mounting with DIN Rail Installation Kit.....................................26
Figure 10 Vertical Pole.............................................................................27
Figure 11 Horizontal Pole.........................................................................27
Figure 12 Mounting the Rain Shield with Installation Kit..........................28
Figure 13 Panel Mounting Frame.............................................................29
Figure 14 Panel Mounting Dimensions (mm/inch) ...................................29
Figure 15 Cable Bushings........................................................................30
Figure 16 Grounding the Screen of Electrical Cable................................31
Figure 17 Screw Terminal Block on the Motherboard..............................32
Figure 18 Connections to 24 VAC Power Supply.....................................34
Figure 19 DMT342 Installation (without the Sampling Cell).....................35
Figure 20 HMP302SC Optional Sampling Cell.........................................36
Figure 21 DMT344 Probe.........................................................................37
Figure 22 Tightening the Nut....................................................................38
Figure 23 Cleaning of the Tightening Cone..............................................38
Figure 24 DMT347 Probe with Swagelok Installation Kit .........................39
Figure 25 DMT347 Probe Installation to Pipeline with Swagelok
Installation Kit...........................................................................40
Figure 26 DMT348 Probe.........................................................................41
Figure 27 Leak Screw in the DMT348 Probe...........................................42
Figure 28 Sealing of Fitting Body into Process ........................................42
Figure 29 Tightening the Clasp Nut..........................................................43
Figure 30 Installing the DMT348 Probe Through a Ball Valve
Assembly..................................................................................45
Figure 31 Probe in Leak Screw Installation..............................................47
Figure 32 DM240FA with Probe...............................................................48
Figure 33 Example of Installing the Probe Directly on the Process Pipe.49
Figure 34 Sampling Cells DMT242SC2 and DMT242SC ........................50
Figure 35 Installing the Probe in High Temperatures...............................51
Figure 36 Power Supply Module ..............................................................52
Figure 37 Galvanic Output Isolation Module............................................57
Figure 38 Third Analog Output.................................................................57
Figure 39 Third Analog Output Selection.................................................58
Figure 40 Relay Module ...........................................................................60
Figure 41 RS-422/485 Module .................................................................61
Figure 42 4-Wire RS-485 Bus ..................................................................63
Figure 43 2-Wire RS-485 Bus ..................................................................64
Figure 44 LAN Interface Module...............................................................66
Figure 45 WLAN Interface Module...........................................................67
Figure 46 Data Logger Module.................................................................69
Figure 47 Pinout of the Optional 8-Pin Connector....................................70
Figure 48 Basic Display............................................................................72
Figure 49 Graphical Display.....................................................................73
Figure 50 Graphical Display with Data Logger.........................................74
Figure 51 Main Views...............................................................................75
Figure 52 Alarm Limits Shown on Graph Screen.....................................79

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Figure 53 Display Alarm Active.................................................................79
Figure 54 Display Alarms..........................................................................80
Figure 55 Modifying an Alarm Limit..........................................................80
Figure 56 Service Port Connector and User Port Terminal on the
Motherboard .............................................................................82
Figure 57 Connection Example between PC Serial Port and User Port ..83
Figure 58 Network Interface Menu ...........................................................87
Figure 59 IP Configuration Menu..............................................................87
Figure 60 Wireless LAN Settings..............................................................90
Figure 61 Entering Network SSID.............................................................90
Figure 62 Selecting the Wireless Network Type.......................................90
Figure 63 Web Configuration Interface for WLAN....................................93
Figure 64 Opening a Serial Connection....................................................94
Figure 65 Opening a Telnet Connection...................................................95
Figure 66 Pressure Set Buttons on the Motherboard.............................107
Figure 67 Device Information on Display...............................................110
Figure 68 Current/Voltage Switches of Output Modules ........................124
Figure 69 Measurement-Based Relay Output Modes............................130
Figure 70 FAULT/ONLINE STATUS Relay Output Modes.....................132
Figure 71 Relay Availability ....................................................................134
Figure 72 Following AutoCal on the Display...........................................139
Figure 73 Sensor Purge Settings............................................................140
Figure 74 Performing Sensor Purge.......................................................140
Figure 75 Serial Interface Settings .........................................................145
Figure 76 IP Configuration......................................................................147
Figure 77 Wireless LAN Settings............................................................147
Figure 78 Communication Protocol ........................................................148
Figure 79 MODBUS Counters................................................................150
Figure 80 Error Indicator and Error Message.........................................154
Figure 81 Starting the Adjustment..........................................................160
Figure 82 Performing Purge ...................................................................160
Figure 83 Following the RH Trend on Graphical Display .......................161
Figure 84 Ending Adjustment of Point 1.................................................161
Figure 85 Proceeding to Adjustment of Point 2......................................161
Figure 86 Completing Adjustment of Point 2..........................................161
Figure 87 Following Stabilization............................................................163
Figure 88 Proceeding with T d/f Adjustment............................................163
Figure 89 Completing T d/f Adjustment....................................................163
Figure 90 Dewpoint Accuracy Graph......................................................169
Figure 91 DMT340 Transmitter Body Dimensions .................................176
Figure 92 WLAN Antenna Dimensions...................................................177
Figure 93 Sampling Cell Dimensions......................................................177
Figure 94 DMT342 Probe Dimensions ...................................................178
Figure 95 DMT344 Probe Dimensions ...................................................178
Figure 96 DMT347 Probe Dimensions ...................................................179
Figure 97 DMT348 Standard Probe Dimensions....................................179
Figure 98 NPT 1/2" Nut Dimensions.......................................................180
Figure 99 DMT348 Optional 400mm Probe Dimensions........................180

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List of Tables
Table 1 Manual Revisions.....................................................................12
Table 2 Quantities and Their Abbreviations..........................................17
Table 3 Optional Quantities and Their Abbreviations ...........................18
Table 4 DMT348 Probe Dimensions.....................................................42
Table 5 Connecting the Twisted Pair Wires to the Screw Terminals....62
Table 6 4-Wire (Switch 3: On)...............................................................63
Table 7 2-Wire (Switch 3: Off)...............................................................64
Table 8 Observation Periods and Resolution........................................68
Table 9 Wiring of the Optional 8-Pin Connector....................................70
Table 10 Periods for Trend and Max/Min Calculations...........................73
Table 11 Graph Information Messages...................................................74
Table 12 Default Serial Communication Settings for the User Port........83
Table 13 Communication Settings for the Service Port ..........................85
Table 14 IP Settings for the LAN and WLAN Interfaces .........................86
Table 15 Wireless LAN Settings..............................................................89
Table 16 Measurement Commands........................................................96
Table 17 Formatting Commands.............................................................96
Table 18 Data Recording Commands.....................................................97
Table 19 Purge Commands ....................................................................97
Table 20 Autocalibration Commands......................................................97
Table 21 Calibration and Adjustment Commands...................................97
Table 22 Setting and Testing the Analog Outputs ..................................97
Table 23 Setting and Testing the Relays................................................97
Table 24 Other Commands.....................................................................98
Table 25 FORM Command Modifiers....................................................104
Table 26 Conversion Factors for Pressure Units..................................108
Table 27 Filtering Levels.......................................................................109
Table 28 Selection of Output Modes.....................................................117
Table 29 Relay State Examples............................................................133
Table 30 Supported MODBUS Variants................................................143
Table 31 Error Messages......................................................................155
Table 32 Indicator Led Functions..........................................................158
Table 33 Options and Accessories........................................................174
Table 34 Supported Function Codes ....................................................185
Table 35 DMT340 MODBUS Register Blocks.......................................186
Table 36 Measurement Data Registers ................................................188
Table 37 Status Registers.....................................................................189
Table 38 Configuration Parameter Registers........................................189
Table 39 Configuration Flag Registers..................................................190
Table 40 DMT340 Exception Status Outputs........................................190
Table 41 DMT340 MODBUS Diagnostics.............................................191
Table 42 DMT340 MODBUS Device Identification ...............................192
Table 43 DMT340 MODBUS Exception Responses.............................192

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Chapter 1 ________________________________________________________ General Information
VAISALA_______________________________________________________________________ 11
CHAPTER 1
GENERAL INFORMATION
About This Manual
This manual provides information for installing, operating, and
maintaining Vaisala DRYCAP®Dewpoint and Temperature Transmitter
Series DMT340.
Contents of This Manual
This manual consists of the following chapters:
- Chapter 1, General Information, provides general notes for the manual
and the product.
- Chapter 2, Product Overview, introduces the features, advantages, and
the product nomenclature of the DMT340.
- Chapter 3, Installation, provides you with information that is intended
to help you install the product.
- Chapter 4, Operation, contains information that is needed to operate
the product.
- Chapter 5, MODBUS, contains information that is needed when
operating the transmitter using the MODBUS protocol.
- Chapter 6, Maintenance, contains information that is needed in basic
maintenance of the product.
- Chapter 7, Calibration and Adjustment, provides information and
instructions concerning the calibration and adjustment of the
DMT340.
- Chapter 8, Technical Data, provides the technical data of the product.
- Appendix A, Calculation Formulas, presents the equations used for
the calculated output quantities.
- Appendix B, MODBUS Reference, describes the MODBUS functions
and data of the transmitter.

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Version Information
Table 1 Manual Revisions
Manual Code Description
M210704EN-F May 2011. This manual. Applicable from
transmitter software version 5.10 onward.
Added MODBUS protocol. Updated serial line
command descriptions. Updated storage
temperature range.
M210704EN-E Previous version. Added PuTTY terminal
application instructions, revised description of the
MI70 Link software. Removed instructions for
HyperTerminal.
Documentation Conventions
Throughout the manual, important safety considerations are highlighted
as follows:
WARNING 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 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 Note highlights important information on using the product.

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VAISALA_______________________________________________________________________ 13
Safety
The DMT340 Dewpoint and Temperature Transmitter delivered to you
has been tested for safety and approved as shipped from the factory. Note
the following precautions:
WARNING Ground the product, and verify outdoor installation grounding
periodically to minimize shock hazard.
CAUTION Do not modify the unit. Improper modification can damage the product,
lead to malfunction, or make the product noncompliant with applicable
legislation.
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
to the equipment chassis before touching the boards. Ground yourself
with a wrist strap and a resistive connection cord. When neither of the
above is possible, 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.
Recycling
Recycle all applicable material.
Dispose of batteries and the unit according to statutory regulations. Do
not dispose of with regular household refuse.

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Regulatory Compliances
EU Declaration of Conformity
The Vaisala Vaisala HUMICAP® Humidity and Temperature
Transmitter Series DMT340 is in conformity with the provisions of the
following EU directives:
- Low Voltage Directive
- EMC-Directive
Conformity is shown by compliance with the following standards:
- EN 60950-1
- EN 61326-1: Electrical equipment for measurement, control, and
laboratory use – EMC requirements – for use in industrial locations.
- EN 550022: Information technology equipment – Radio disturbance
characteristics – Limits and methods of measurement.
Transmitters with LAN or WLAN Interface
This equipment has been tested and found to comply with the limits for a
Class B digital device, pursuant to Part 15 of the FCC Rules. These limits
are designed to provide reasonable protection against harmful
interference in a residential installation. Operation is subject to the
following two conditions: (1) this device may not cause interference, and
(2) this device must accept any interference, including interference that
may cause undesired operation of the device.
This equipment generates, uses and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may
cause harmful interference to radio communications. However, there is
no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and on,
the user is encouraged to try to correct the interference by one or more of
the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to
which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.

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VAISALA_______________________________________________________________________ 15
Transmitters with WLAN Interface
This device has been designed to operate with a 2 dBi half-wave antenna.
Antennas with a gain greater than 2 dB are strictly prohibited for use with
this device. The required antenna impedance is 50 ohms.
To reduce potential radio interference to other users, the antenna type and
its gain should be so chosen that the equivalent isotropically radiated
power (e.i.r.p.) is not more than that permitted for successful
communication.
This Class [B] digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe [B] est conforme à la norme NMB-
003 du Canada.
Patent Notice
The Vaisala DRYCAP® Dewpoint and Temperature Transmitter Series
DMT340 is protected by, for example, the following patents and their
corresponding national rights:
Finnish patents 98861 and 99164, French patents 6650303 and 9504397,
German patents 69418174 and 19513274, Japanese patents 3585973 and
2801156, UK patents 0665303 and 2288465, and U.S. patent 5607564.
Trademarks
DRYCAP® is a registered trademark of Vaisala Oyj.
Windows® is a registered trademark 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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Warranty
Visit our Internet pages for more information and our standard warranty
terms and conditions: www.vaisala.com/services/warranty.html.
Please observe that any such warranty may not be valid in case of
damage due to normal wear and tear, exceptional operating conditions,
negligent handling or installation, or unauthorized modifications. Please
see the applicable supply contract or Conditions of Sale for details of the
warranty for each product.

Chapter 2 __________________________________________________________ Product Overview
VAISALA_______________________________________________________________________ 17
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features, advantages, and the product
nomenclature of the Vaisala DRYCAP® Dewpoint and Temperature
Transmitter DMT340 Series.
Introduction to DMT340
The DMT340 transmitter measures dewpoint temperature accurately in a
measurement range from -60ºC to +80 ºC (-76 ... +176 ºF). The AutoCal
feature provides excellent long term stability of the measurement.
DMT340 incorporates the advanced DRYCAP® technology, which
enables reliable and high-performance dewpoint measurement.
Apart from the extended dewpoint measurement range the optional
modules provide for more flexibility. See Table 2 below for the
quantities that DMT340 measures and calculates. See Table 3 below for
the optional quantities measured by DMT340.
Table 2 Quantities and Their Abbreviations
Quantity Abbreviation Metric Unit Non-Metric
Unit
Dewpoint/frost point
temperature (Td/f ) TDF ºC ºF
Mixing ratio (x) X g/kg gr/lb
Parts per million H2O ppmv/ ppmwppmv/ ppmw

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Table 3 Optional Quantities and Their Abbreviations
Quantity Abbreviation Metric Unit Non-Metric
Unit
Relative humidity RH RH %RH %RH
Temperature T T ºC ºF
Dewpoint/frost point in the
atmospheric pressure (Td/f ) TDFA ºC atm ºF atm
Absolute humidity (a) A g/m3gr/ft3
Absolute humidity in standard
pressure and temperature (NTP) ANTP g/m3gr/ft3
Wet bulb temperature (Tw) TW ºC ºF
Water vapor pressure (Pw ) PW hPa lb/in2
Water vapor saturation pressure
(Pws) PWS hPa lb/in2
Enthalpy (h) H kJ/kg Btu/lb
Difference of T and Td/f (∆T) DT ºC ºF
Dewpoint temperature (Td )* TD ºC ºF
Dewpoint in the atmospheric
pressure (Td )* TDA ºC atm ºF atm
*Use these parameters only if you need dewpoint over water below 0 ºC/32ºF and not
over ice (industry standard)
Basic Features and Options
- Dewpoint measurement with AutoCal and sensor purge features
- Sensor warming in high humidities
- Two analog outputs and a serial interface
- Several probes for different applications
- User friendly multilingual display option
- Calculated output quantities available
- Different probe mounting kits, sensor protection options and probe
cable lengts 2 m, 5 m or 10 m
- Support for MODBUS serial communications protocol
- USB connectivity for service connections via the optional
USB-RJ45 cable
- Optional modules:
- Galvanic isolation for outputs
- AC mains power supply
- RS-422/485-module
- LAN and WLAN interfaces
- Data logger module with real time clock
- Additional analog output module
- Alarm relay module