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M211289EN-B
User Guide
Vaisala HUMICAPâ Dew Point Transmitter
DMT132
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PUBLISHED BY
Vaisala Oyj
Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
P.O. Box 26, FI-00421 Helsinki, Finland
+358 9 8949 1
Visit our Internet pages at www.vaisala.com.
© Vaisala Oyj 2018
No part of this manual may be reproduced,
published or publicly displayed in any form or by
any means, electronic or mechanical (including
photocopying), nor may its contents be modified,
translated, adapted, sold or disclosed to a third
party without prior written permission of the
copyright holder. Translated manuals and
translated portions of multilingual documents are
based on the original English versions. In
ambiguous cases, the English versions are
applicable, not the translations.
The contents of this manual are subject to change
without prior notice.
Local rules and regulations may vary and they
shall take precedence over the information
contained in this manual. Vaisala makes no
representations on this manual’s compliance with
the local rules and regulations applicable at any
given time, and hereby disclaims any and all
responsibilities related thereto.
This manual does not create any legally binding
obligations for Vaisala towards customers or end
users. All legally binding obligations and
agreements are included exclusively in the
applicable supply contract or the General
Conditions of Sale and General Conditions of
Service of Vaisala.
This product contains software developed by
Vaisala or third parties. Use of the software is
governed by license terms and conditions
included in the applicable supply contract or, in
the absence of separate license terms and
conditions, by the General License Conditions of
Vaisala Group.
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Table of Contents
1. About This Document..................................................................................... 5
1.1 Version Information.............................................................................................5
1.2 Related Manuals...................................................................................................5
1.3 Documentation Conventions............................................................................. 5
1.4 Trademarks...........................................................................................................6
2. Product Overview..............................................................................................7
2.1 Introduction to DMT132.......................................................................................7
2.2 Basic Features and Options............................................................................... 8
2.3 Transmitter Structure.......................................................................................... 8
2.4 LED Indicator Plug (Optional)............................................................................9
2.5 Special Cover Set for HMK15 (Optional)......................................................... 10
2.6 NPT Adapter (Optional)..................................................................................... 11
2.7 Loop-Powered Display (Optional).................................................................... 11
2.8 Connection Cables............................................................................................. 12
2.9 Sampling Accessories........................................................................................ 13
2.10 Safety...................................................................................................................13
2.10.1 ESD Protection.............................................................................................14
2.11 Regulatory Compliances................................................................................... 14
3. Installation.......................................................................................................... 15
3.1 Selecting Location............................................................................................. 15
3.2 Installing Transmitter......................................................................................... 16
3.3 Wiring..................................................................................................................19
3.3.1 Power Supply Requirements.................................................................... 20
3.4 Sampling from a Process...................................................................................21
3.5 Sampling Accessories for DMT132................................................................... 21
3.5.1 DMT242SC Sampling Cell........................................................................... 21
3.5.2 DMT242SC2 Sampling Cell with Swagelokâ Connectors..................... 22
3.5.3 DSC74 Sampling Cell with Quick Connector and Leak Screw...............22
3.5.4 DSC74B Two-Pressure Sampling Cell.......................................................23
4. Operation........................................................................................................... 29
4.1 Getting Started..................................................................................................29
4.2 Serial Communication...................................................................................... 29
4.2.1 Connecting to Serial Interface.................................................................. 29
4.2.2 Terminal Application Settings...................................................................30
4.3 List of Serial Commands....................................................................................31
4.4 Device Information and Status........................................................................ 32
4.4.1 Show Device Information...........................................................................32
4.4.2 Show Available Measurement Parameters.............................................. 33
4.4.3 Show Firmware Version.............................................................................33
4.4.4 Show Software Information...................................................................... 33
4.5
Configuring Analog Output.............................................................................34
4.5.1 Set Analog Output Measurement Parameter and Scaling.................... 34
4.5.2 Set Analog Output Error Notification...................................................... 35
4.6 Configuring Measurement Parameters.......................................................... 36
4.6.1 Set Pressure Value for Dew Point Calculation.........................................36
Table of Contents
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4.7 Serial Line Output Commands.........................................................................37
4.7.1 Output a Reading Once............................................................................. 37
4.8 Troubleshooting and Maintenance Commands.............................................37
4.8.1 Display Currently Active Errors.................................................................37
4.8.2 Test Analog Output.................................................................................... 38
4.8.3 Set LED Indicator Level..............................................................................38
4.9 Calibration and Adjustment Commands........................................................39
4.9.1 Calibrate Humidity Measurement.............................................................39
4.9.2 Calibrate Temperature Measurement...................................................... 40
4.9.3 Adjust Capacitance Measurement.............................................................41
4.9.4 View User Adjustment Parameters.......................................................... 42
4.9.5 Set User Adjustment Parameters............................................................. 42
4.10 Other Commands..............................................................................................43
4.10.1 Display Command List...............................................................................43
4.10.2 Reset Transmitter....................................................................................... 43
4.10.3 Restore Factory Settings...........................................................................44
5. Maintenance......................................................................................................45
5.1 Cleaning Transmitter........................................................................................ 45
5.2 Changing Filter..................................................................................................45
5.3 Changing Sensor...............................................................................................46
5.4 Calibration and Adjustment.............................................................................47
5.4.1 Field Check Using DM70............................................................................48
5.4.2 Humidity Calibration and Adjustment (RHCAL).................................... 50
5.4.3 Temperature Calibration and Adjustment (CT)...................................... 53
5.4.4 Capacitance Adjustment (CRH)................................................................55
6. Troubleshooting.............................................................................................. 59
6.1 Typical Problems...............................................................................................59
6.2 Error State..........................................................................................................59
6.3 Error Codes........................................................................................................60
7. Technical Data.................................................................................................. 63
7.1 Dimensions........................................................................................................ 65
7.2 Spare Parts and Accessories........................................................................... 66
Warranty
........................................................................................................................ 67
Technical Support...................................................................................................... 67
Recycling.......................................................................................................................67
DMT132 User Guide M211289EN-B
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List of Figures
Figure 1 Vaisala HUMICAPâ Dew Point Transmitter DMT132................................. 8
Figure 2 DMT132 Transmitter Structure.........................................................................9
Figure 3 DMT132 with LED Indicator Plug...................................................................10
Figure 4 Special Cover Set for HMK15..........................................................................10
Figure 5 DMT132 with NPT Adapter...............................................................................11
Figure 6 Nokeval 301 Loop-Powered Display.............................................................12
Figure 7 Cable with Threaded Connector....................................................................13
Figure 8 USB Service Cable............................................................................................. 13
Figure 9 Removing the Transport Protection Cap.................................................... 16
Figure 10 Installing the Transmitter.................................................................................17
Figure 11 Tightening by Hand...........................................................................................17
Figure 12 Tightening with Plastic Wrench..................................................................... 18
Figure 13 Connecting the Cable and LED Indicator Plug..........................................19
Figure 14 Connectors I and II........................................................................................... 20
Figure 15 Connector Pinout..............................................................................................20
Figure 16 Sampling Cells DMT242SC2 (Left) and DMT242SC (Right)..................22
Figure 17 DSC74 Sampling Cell with Accessories.......................................................23
Figure 18 DSC74B................................................................................................................ 24
Figure 19 Removing the Leak Screw.............................................................................. 25
Figure 20 Default Assembly of DSC74C........................................................................ 26
Figure 21 Alternative Assembly of DSC74C (for Tight Spaces)..............................27
Figure 22 DM240FA Duct Installation Flange with DMT132.....................................28
Figure 23 PuTTY Terminal Application........................................................................... 31
Figure 24 Opening the Filter............................................................................................ 45
Figure 25 Filter Structure.................................................................................................. 46
Figure 26 Removing the HUMICAPâ 180R Sensor.....................................................47
Figure 27 Calibrating DMT132 Using HMK15 and USB Cable...................................50
Figure 28 Accuracy Over Temperature Range.............................................................63
Figure 29 DMT132 Dimensions......................................................................................... 65
Figure 30 Dimensions with NPT Adapter and LED Plug...........................................65
List of Figures
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List of Tables
Table 1 Document Versions................................................................................................5
Table 2 Related Manuals..................................................................................................... 5
Table 3 DMT132 Measurement Parameters.................................................................... 7
Table 4 Connector Pinouts................................................................................................19
Table 5 DMT132 Serial Interface Settings.....................................................................30
Table 6 DMT132 Serial Commands.................................................................................. 31
Table 7 Pressure Conversion Coecients....................................................................36
Table 8 Error Codes........................................................................................................... 60
Table 9 Measurement Performance...............................................................................63
Table 10 Operating Environment..................................................................................... 63
Table 11 Outputs.................................................................................................................. 64
Table 12 Mechanical Specifications................................................................................. 64
Table 13 Output Cable Specifications.............................................................................64
Table 14 Spare Parts and Accessories............................................................................ 66
DMT132 User Guide M211289EN-B
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1. About This Document
1.1 Version Information
This document provides instructions for installing, operating, and maintaining Vaisala
HUMICAPâ Dew Point Transmitter DMT132.
Table 1 Document Versions
Document Code Date Description
M211289EN-B August 2018 This manual.
Changes since the previous version:
• Note about pressure compensation setting added in Calibration and
Adjustment (page 47)
• Technical specifications updated with regard to measurement
range, response time, and operating temperature
• Patent Notice section removed
M211289EN-A March 2011 First version.
1.2 Related Manuals
Table 2 Related Manuals
Document Code Name
M211288EN Vaisala HUMICAPâ Dewpoint Transmitter DMT132 Quick Guide
M210185EN Vaisala Humidity Calibrator HMK15 User’s Guide
1.3 Documentation Conventions
Warning alerts you to a serious hazard. If you do not read and follow
instructions carefully at this point, there is a risk of injury or even death.
WARNING!
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.
CAUTION!
Chapter 1 – About This Document
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Note highlights important information on using the product.
Tip gives information for using the product more eciently.
Lists tools needed to perform the task.
Indicates that you need to take some notes during the task.
1.4 Trademarks
Vaisalaâ and HUMICAPâ are registered trademarks of Vaisala Oyj.
Windowsâ is either a registered trademark or trademark of Microsoft Corporation in the
United States and other countries.
All other product or company names that may be mentioned in this publication are trade
names, trademarks, or registered trademarks of their respective owners.
DMT132 User Guide M211289EN-B
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2. Product Overview
2.1 Introduction to DMT132
The Vaisala HUMICAPâ Dew Point Transmitter DMT132 measures dew point temperature
within measurement range -30 ... +50 °C (-22 ... +122 °F) Td. The DMT132 is designed for OEM
applications that require dew point measurement in this range, such as refrigeration dryers.
The transmitter is easy to install, and the mechanics have been designed for harsh
environments requiring protection against dust, dirt, and splashed water.
The excellent stability and reliability of the transmitter’s performance is based on advanced
HUMICAPâ polymer sensor technology. The HUMICAPâ technology has low maintenance
needs due to its excellent long-term stability and durability against condensation.
Table 3 DMT132 Measurement Parameters
Parameter Abbreviation Metric Unit Non Metric
Unit
Dew point/frost point temperature T
d/f
°C °F
Dew point/frost point temperature in
atmospheric pressure
T
d/f
atm °C °F
Dew point temperature (T
d/f
) is the primary measurement parameter of the DMT132. Dew
point temperature in atmospheric pressure (T
d/f
atm) is a calculated measurement
parameter that presents the dew point the gas would have at atmospheric pressure. For this
calculation to provide accurate results, it is important to have the correct pressure setting
stored in the transmitter. This setting is
specified on the order form, and it can be changed
using the service port. See Set Pressure Value for Dew Point Calculation (page 36).
When dew point is below 0 °C, the transmitter outputs frost point for T
d
.
Chapter 2 – Product Overview
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Figure 1 Vaisala HUMICAPâ Dew Point Transmitter DMT132
2.2 Basic Features and Options
• Dew point measurement range -30 ... +50 °C (-22 ... +122 °F) T
d
• Output in T
d/f
or T
d/f
atm (calculated measurement parameter)
• HUMICAPâ polymer sensor
• Small size to fit in tight installations
• One scalable 2-wire current loop output, 4 ... 20 mA
•
Configurable analog output level for error notification
• Field check suitability with MI70 hand-held indicator
• Optional accessories:
• USB service cable for
configuration and calibration
• LED indicator plug that enables a visual indication of transmitter status: LED lit when
dew point is above set limit, blinking for malfunction alarm
• Special cover set for HMK15 Humidity Calibrator
• Adapter for mounting on NPT 1/2" threaded mounting points
• Loop-powered display
• Various sampling cells with
dierent installation options
2.3
Transmitter Structure
The structure of the DMT132 is shown in Figure 2 (page 9). The transmitter body does not
have user serviceable parts inside, and is not designed to be opened. Opening the
transmitter will void the warranty.
DMT132 User Guide M211289EN-B
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1
2
4
3
6
5
7
Figure 2 DMT132 Transmitter Structure
1 30-mm nut
2 Transmitter body
3 4-pin M8 connector I: analog output and operating power
4 4-pin M8 connector II (shown with protective cap): Connection for service port (RS-485,
service use only ) and LED indicator plug
5 Sealing ring (included with every transmitter)
6 Connection thread (ISO G1/2")
7 Tube filter that protects the HUMICAPâ and Pt1000 sensors
When the transmitter is delivered, the filter is protected by a yellow transport protection cap
that keeps the sensor dry. The transport protection cap should be left on the transmitter
during storage. Remove the transport protection cap before installing the transmitter.
2.4
LED Indicator Plug (Optional)
The service port (connector II) of the DMT132 can be equipped with a LED indicator plug
(Vaisala order code 230388). The red LED on the plug will light up when the measured dew
point temperature is above the set limit. If the transmitter is in error condition, the LED will
blink.
Chapter 2 – Product Overview
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Figure 3 DMT132 with LED Indicator Plug
The dew point limit for the LED indication can be changed using the service port; see
Serial Communication (page 29).
2.5 Special Cover Set for HMK15
(Optional)
To use the Vaisala Humidity Calibrator HMK15 with the DMT132 you need the special cover
set (Vaisala order code 230914). The cover set includes one salt jar cover where one of the
holes is specially designed for the DMT132, and rubber plugs for covering the unused holes.
The hole for DMT132 is raised higher than the others, and has an ISO G 1/2" thread. The
DMT132 can be mounted on the salt jar tightly using the thread, and without having to
remove the
filter.
Figure 4 Special Cover Set for HMK15
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2.6 NPT Adapter (Optional)
The DMT132 can be connected to NPT 1/2" threaded mounting points using the optional NPT
adapter (Vaisala order code 210662).
Figure 5 DMT132 with NPT Adapter
When the NPT adapter is used, the
filter is partially covered by the adapter; see Figure 5
(page 11). This doubles the response time of the transmitter.
The adapter is suitable for use in compressed air lines and other systems with sucient
flow.
2.7 Loop-Powered Display (Optional)
The DMT132 can be connected to a loop-powered external LED display (type Nokeval 301,
Vaisala order code 226476). The display provides a reading of the output measurement
parameter. The display is powered by the 4 ... 20 mA current signal, so there is no need for
an external power supply.
The display is delivered at its default settings.
Configure the display functions and scaling
according to the documentation delivered with the display.
Chapter 2 – Product Overview
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Figure 6 Nokeval 301 Loop-Powered Display
The loop resistance of the display must be included in the loop resistance calculation for
the complete current loop. See Power Supply Requirements (page 20).
For the loop resistance of the display, refer to the manufacturer’s documentation.
2.8 Connection Cables
Vaisala supplies shielded cables with M8 female straight threaded connector. Available in
four lengths:
• 0.3 m (1.0 ft)
• 3 m (9.8 ft)
• 5 m (16.4 ft)
• 10 m (32.8 ft)
Also available are cables for service port and
field check use:
• USB service cable
• MI70 connection cable
DMT132 User Guide M211289EN-B
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Figure 7 Cable with Threaded Connector
Figure 8 USB Service Cable
More Information
‣
Spare Parts and Accessories (page 66)
2.9
Sampling Accessories
DMT132 is compatible with various sampling accessories. For more information on
performing sampling, and a description of the accessories, see Sampling Accessories for
DMT132 (page 21).
For order codes of sampling accessories, see Spare Parts and Accessories (page 66).
2.10
Safety
The Vaisala HUMICAPâ Dew Point Transmitter DMT132 delivered to you has been tested for
safety and approved as shipped from the factory. Note the following precautions:
Chapter 2 – Product Overview
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Ground the product and verify installation grounding periodically to
minimize shock hazard.
WARNING!
Do not modify the unit or use it in ways not described in the documentation.
Improper
modification may lead to safety hazards, equipment damage, failure to
perform according to specification, or decreased equipment lifetime.
CAUTION!
2.10.1 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 an electrostatic discharge when touching,
removing or inserting any objects inside the equipment housing.
Avoid touching component contacts or connectors when working with the device.
2.11 Regulatory Compliances
The Vaisala HUMICAPâ Dew Point Transmitter DMT132 is in conformity with the provisions
of the following EU directive:
• EMC-Directive (2004/108/EC)
Conformity is shown by compliance with the following standards:
• 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
DMT132 User Guide M211289EN-B
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3. Installation
3.1 Selecting Location
It is important that the conditions at the point of installation represent well the gas to be
measured. Temperature changes do not
aect the dew point measurement, but pressure
changes will have an
eect on dew point. All leaks in the system must be eliminated to avoid
ambient humidity
aecting the measurement.
Direct installation to the measured gas is the recommended installation method if the
temperature of the gas is suitable for DMT132 and no additional filtering is needed due to
very dusty or oily gas. Oil as such is not harmful for the HUMICAPâ sensor, but response
time may be slower if there are oil particles in the system, or if oil is collected to the
filter
over a longer period of time. The maximum measurement pressure is 20 bara / 290 psi
a
(absolute pressure) for direct measurement.
If the gas temperature is higher than the specified maximum operating temperature of the
transmitter, gas sampling and cooling it to ambient temperature (for example, 20 °C / 68 °F)
is recommended. Note that the dew point temperature must be clearly lower than the
ambient temperature to avoid condensation in the sampling line. Sampling from the process
is easy by using Vaisala sampling cell options.
The DMT132 is light in weight, which means that it can be installed in a sample pipeline in the
sampling cells without the need for any additional mechanical support.
More Information
‣
Sampling Accessories for DMT132 (page 21)
Chapter 3 – Installation
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3.2 Installing Transmitter
Before proceeding with the installation, select first a suitable measurement location. See
Selecting Location (page 15).
1. Remove the yellow transport protection cap from the transmitter.
Figure 9 Removing the Transport Protection Cap
2. If you are using the optional NPT adapter, apply PTFE tape or suitable paste sealant to
the outer thread of the adapter. Follow the application instructions of the sealant.
3. Install the adapter to the mounting point.
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4. Make sure that the threads on the mounting point are of the correct type, and fasten
the transmitter to the measurement point. Always leave the sealing ring in place, it is
always needed to achieve a tight installation. Use your hands to turn the transmitter
from the 30 mm nut until it feels tight. Do not use force at this point, and check that the
sealing ring remains centered.
Figure 10 Installing the Transmitter
Figure 11 Tightening by Hand
Chapter 3 – Installation
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5. Use the supplied plastic 30 mm wrench to tighten the connection. Sucient tightness
is achieved by turning 20 degrees after the point achieved by hand.
Only tighten the transmitter from the 30 mm nut. Do NOT apply force
to other points in the transmitter body.
CAUTION!
20
º
Figure 12 Tightening with Plastic Wrench
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6. Connect the wires of the connection cable. When using cables provided with DMT132,
refer to Wiring (page 19). See also Power Supply Requirements (page 20).
Figure 13 Connecting the Cable and LED Indicator Plug
7. Plug in the cable to connector I of the transmitter and tighten it. For connector pinout,
see Wiring (page 19).
8. If you have the LED indicator plug option, plug it in to connector II of the transmitter
and tighten it.
9. Turn on the power supply to start up the DMT132. The analog output will stabilize in
five
seconds after start-up.
3.3
Wiring
The power supply lines on connector II are intended for use by the USB
service cable and the MI70 hand-held indicator. Do not connect other power supplies to
connector II.
CAUTION!
Table 4 Connector Pinouts
Pin Connector I Connector II Wire color
1 VDC supply+ VDC supply+ Brown
2 Not connected RS-485 D0- White
3 GND GND Blue
4 Not connected RS-485 D1+ Black
Chapter 3 – Installation
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Figure 14 Connectors I and II
＋
−
1 = VDC+
3 = GND
mA
Vs
2
4
1 3
2
4
1 3
＋
−
1 = VDC+
Vs
3 = GND
4 = RS-485 D1+
2 = RS-485 D0-
RS-485
Figure 15 Connector Pinout
3.3.1
Power Supply Requirements
The DMT132 transmitters are designed to operate with a supply voltage of 10 ... 28 VDC. The
allowed voltage range depends on the loop resistance (RL):
• For RL 0 ... 100 Ω, supply voltage range is 10 ... 20 VDC
• For RL 0 ... 500 Ω, supply voltage range is 20 ... 28 VDC
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Maximum allowed RL is 600 Ω, as long as the following equation applies:
min
=
40
+ 7 . 5
When RL = 600 Ω, supply voltage range is 22.5 ... 28 VDC.
The DMT132 can be powered by the MI70 indicator or the USB service cable. You can plug
in the MI70 indicator or the USB service cable while the transmitter is powered from
connector I.
3.4 Sampling from a Process
Sampling is needed when direct measurement of the air or gas is not possible or desirable.
This may be related to, for example, a high process temperature, protecting the sensor from
water spikes, the need to easily detach the instrument from a pressurized process without
running the whole process down, or wanting to make the measurement at a more
convenient location.
Keep in mind that changing the pressure of a gas changes the dew point temperature of the
gas. If the sensor is at a
dierent pressure than the process itself, there may be an error of
several tens of degrees in the dew point measurement.
Make sure there is sucient flow of gas to the sensor (for example, 1 l/min) to give a
representative sample.
You can use the Vaisala Humidity Calculator to simulate the
eect of pressure change to
dew point. The Humidity Calculator is available at: www.vaisala.com/humiditycalculator.
3.5 Sampling Accessories for DMT132
3.5.1 DMT242SC Sampling Cell
The DMT242SC is a basic sampling cell with only the main sampling cell body. The inlet and
outlet are female threaded sample connectors (inlet G3/8", outlet G1/4" ISO). See Figure 16
(page 22).
The DMT242SC is suitable for users requiring only a sampling cell to
fit the transmitter into
and doing further assembly (piping into inlet and outlet, valves, possible flow meter) by
themselves.
Chapter 3 – Installation
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Page 24
3.5.2 DMT242SC2 Sampling Cell with Swagelok Connectors
The DMT242SC2 is similar to DMT242SC, but connections are made easy. The sampling cell
includes welded Swagelok connectors at both the inlet and outlet that fit directly to 1/4"
tubing.
To
fit 6 mm tubing to the connectors, you can use an adapter such as Swagelok Reducer
SS-6M0-R-4 (not supplied by Vaisala).
DMT242SC2 is the suitable choice in, for example, plastics drying systems, where the
measurement is made by tapping
o the dryer system and bringing a small air stream to the
sensor. The Swagelok connectors of DMT242SC2 easily connect to a cooling coil or tubing,
providing the essential function of cooling the dry air to ambient temperature before it
reaches the sensor.
3
2
1
1
2
4
Figure 16 Sampling Cells DMT242SC2 (Left) and DMT242SC (Right)
1 Male pipe welded connector Swagelok 1/4"
2 G1/2"
3 G1/4"
4 G3/8"
3.5.3 DSC74 Sampling Cell with Quick Connector and Leak
Screw
The DSC74 has been designed especially for compressed air lines. The sampling cell contains
an adjustable leak screw that allows keeping up the pipeline pressure at the sensor. Use a
screwdriver to open and close the leak screw. The leak screw should be 1/2 turn open. You
can verify this by
first closing the leak screw, then turning it 1/2 turn to open it. The air
coming out will make a barely audible little hiss. You can feel it lightly when placing a hand
in front of the air stream.
DMT132 User Guide M211289EN-B
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Do not open the leak screw more than 1/2 turn to avoid reducing the pressure in the
sampling cell.
The DSC74 comes with a quick connector that fits to industry standard compressed air line
connectors (suitable for type D, Quick08, NIP08). This allows for easy installation and
detachment of the dew point transmitter without having to shut down the process.
Alternative ways to connect are through the two
dierent thread adapters (G3/8" to G1/2"
and G3/8" to G1/4" ISO), supplied with each DSC74 unit.
When using the DSC74, seal the threads of the quick connector or thread adapter carefully
with PTFE thread seal tape. Tighten with an open-end wrench.
4
3
1
2
5
Figure 17 DSC74 Sampling Cell with Accessories
1 Thread adapter type G3/8" to G1/2"
2 Thread adapter type G3/8" to G1/4"
3 Quick connector
4 Leak screw
5 Sampling cell body (DMT242SC)
3.5.4 DSC74B Two-Pressure Sampling Cell
The DSC74B and DSC74C sampling cells are enhanced versions of the DSC74. The body is
designed in a way that it is possible to measure at both system pressure and atmospheric
pressure.
Chapter 3 – Installation
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Page 26
The DSC74B limits the flow rate with a fixed leak screw. The flow is optimized for pressures
3 ... 10 barg. The fixed leak screw eliminates the risk of opening the leak screw fully by
accident and this way emptying a gas vessel. The maximum flow can be increased, if
needed, by removing the leak screw and adjusting the flow manually with the valve. Harmful
gases can be recovered by connecting a collection system at the outlet (not available from
Vaisala).
In the basic operation of the DSC74B, the gas flows to the sensor from the front and the
outlet is on the side. To have the measurement done at atmospheric pressure, the inlet and
outlet are reversed. Then the reducing parts supplied (G3/8" to G1/2" or G3/8" to G1/4") on
the outlet side help to protect the sensor from ambient humidity coming in.
DSC74B consists of the following parts:
• Sampling cell, thread 3/8"G
• Connection part with a needle valve and an integrated leak screw
• Reducing Nipple (thread adapter), G3/8" to G1/2"
• Reducing Adapter (thread adapter), G3/8" to G1/4"
1
2
Figure 18 DSC74B
1 Gas goes in
2 Gas comes out
DMT132 User Guide M211289EN-B
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Figure 19 Removing the Leak Screw
3.5.4.1 DSC74C Two-Pressure Sampling Cell with Coil
The DSC74C with an outlet coil is designed for the most critical measurements at
atmospheric pressure. In the DSC74C, the coil is connected to the sampling cell outlet to
protect the sensor from ambient humidity disturbing the measurement. The coil can also be
used as a cooling coil for sampling from high temperature processes.
DSC74C consists of the following parts:
• Sampling cell, thread G3/8"
• Connection part with a needle valve and an integrated leak screw
• Reducing Nipple (thread adapter), G3/8" to G1/2"
• Reducing Adapter (thread adapter), G3/8" to G1/4"
•
Diusion coil (for measurements in atmospheric pressure)
Chapter 3 – Installation
25
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3
4
1
2
Figure 20 Default Assembly of DSC74C
1 Gas goes in. The coil can also be used here.
2 Gas comes out
3 Coil
4 Valve
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1
2
3
4
5
Figure 21 Alternative Assembly of DSC74C (for Tight Spaces)
1 Gas comes out
2 Coil
3 Thread, max. size 7 mm
4 Gas goes in
5 Valve
The thread size cannot exceed 7 mm. Use the provided adapter to avoid damage to the
transmitter.
3.5.4.2 DM240FA Duct Installation Flange
The transmitter can be installed directly in the process wall through DM240FA duct
installation
flange. When the transmitter is installed directly on the process wall or pipe, note
that a closing valve may be needed on both sides of the installed transmitter so that the
sensor head can be removed from the process for calibration or maintenance.
Chapter 3 – Installation
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3
1
2
4
Figure 22 DM240FA Duct Installation Flange with DMT132
1 Measured gas
2 DMT132 transmitter
3 DM240FA flange (thread G1/2" ISO)
4 Recommended additional hole (plugged) for Td field check reference measurement
probe (for example, Vaisala DM70)
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4. Operation
4.1 Getting Started
When the transmitter is connected to power supply, there is a delay of three seconds as the
transmitter starts up and the analog output stabilizes. If the LED indicator plug is connected,
it will blink once at start-up.
4.2 Serial Communication
4.2.1 Connecting to Serial Interface
The DMT132 can be connected to a PC using the RS-485 line on Port II. It is recommended
that you use the USB service cable (Vaisala order code 219690) for the connection, since the
cable also provides the operating power from the USB port.
The RS-485 line is intended for service use only.
If you have not used the USB service cable before, install the driver that came with the cable.
See Installing Driver for USB Service Cable (page 29).
4.2.1.1 Installing Driver for USB Service Cable
Before taking the USB service cable into use, you must install the provided USB driver on
your PC. When installing the driver, you must acknowledge any security prompts that may
appear. The driver is compatible with Windows 7, Windows 8, and Windows 10.
1. Check that the USB service cable is not connected. Disconnect the cable if you have
already connected it.
2. Insert the media that came with the cable, or download the driver from
www.vaisala.com/software.
3. Execute the USB driver installation program (setup.exe), and accept the installation
defaults. The installation of the driver may take several minutes.
4. After the driver has been installed, connect the USB service cable to a USB port on your
PC. Windows will detect the new device, and use the driver automatically.
5. The installation has reserved a COM port for the cable. Verify the port number, and the
status of the cable, using the Vaisala USB Instrument Finder program that has been
installed in the Windows Start menu.
Windows will recognize each individual cable as a
dierent device, and reserve a new COM
port. Remember to use the correct port in the settings of your terminal program.
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There is no reason to uninstall the driver for normal use. However, if you wish to remove the
driver files and all Vaisala USB cable devices, you can do so by uninstalling the entry for
Vaisala USB Instrument Driver in Windows Control Panel.
4.2.2 Terminal Application Settings
The serial interface settings of the DMT132 service port are presented in Table 5 (page 30).
The settings cannot be changed by the user.
Table 5 DMT132 Serial Interface Settings
Property Description / Value
Baud rate 19200
Parity None
Data bits 8
Stop bits 1
Flow control None
The steps below describe how to connect to the DMT132 using the PuTTY terminal
application for Windows (available for download at www.vaisala.com/software) and a USB
serial interface cable:
1. Connect the USB serial interface cable between your PC and the RS-485 port of the
DMT132 (connector II).
2. Start the PuTTY application.
3. Select the Serial settings category, and check that the correct COM port is selected in
the Serial line to connect to
field.
You can check which port the USB cable is using with the Vaisala USB Instrument
Finder program that has been installed in the Windows Start menu.
4. Check that the other serial settings are correct for your connection, and change if
necessary.
Flow control should be set to None unless you have a reason to change it.
5. Select Open to open the connection window and start using the serial line.
If PuTTY is unable to open the serial port you selected, it will show you an error
message instead. If this happens, restart PuTTY and check the settings.
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6. You may need to adjust the Local echo setting in the Terminal category to see what
you are typing on the serial line. To access the configuration screen while a session is
running, click the right mouse button over the session window, and select Change
Settings... from the pop-up menu.
Figure 23 PuTTY Terminal Application
4.3
List of Serial Commands
All commands can be issued either in uppercase or lowercase. In the command examples,
the keyboard input by the user is in bold type.
The notation <cr> refers to pressing the carriage return (Enter) key on your computer
keyboard. Enter a <cr> to clear the command buer before starting to enter commands.
Table 6 DMT132 Serial Commands
Command Description
? Show device information
AERR Set analog output device malfunction error mode
ALARM Set analog output limit alarm modes
ASEL Configure analog output measurement parameters ("quantities") and scaling
ATEST Test analog outputs
CALCS Show available measurement parameters
CRH Adjust capacitance measurement after sensor change
CT Calibrate temperature measurement
ERRS Display the currently active errors
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Command Description
FRESTORE Restore factory settings
HELP Display the command list
L View user adjustment parameters
LI Set user adjustment parameters
PASS Access advanced service commands. Requires passcode. Use when instructed by
Vaisala personnel.
PRES Set value for pressure compensation
RHCAL Calibrate humidity measurement
RESET Reset the transmitter
SEND Output the reading once
SYSTEM Show transmitter software information
VERS Show transmitter firmware version
4.4 Device Information and Status
4.4.1 Show Device Information
The ? command outputs a listing of device information.
?<cr>
Example:
>?
>Device Name : DMT132 Dewpoint transmitter
Calibrated : "20110223"
Calibration location: "VAISALA/HEL"
Serial number : "G0831004"
Batch number : "G0000007"
Sensor model : "HUMICAP180R"
Sensor serial number: "F312"
Operating mode : 2 Wire
Transmitter status : NORMAL
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4.4.2 Show Available Measurement Parameters
CALCS<cr>
Example:
>calcs
Tdf Tdf(atm)
>
4.4.3
Show Firmware Version
VERS<cr>
Example:
>vers
DMT132 1.0.0 2011-01-24
4.4.4
Show Software Information
SYSTEM<cr>
Example:
>system
Device Name : DMT132 Dewpoint transmitter
Copyright : Copyright (c) Vaisala Oyj 2011. All rights reserved.
SW Name : DMT132
SW model : VAISALA
SW version : 1.0.0.1214
>
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4.5 Configuring Analog Output
4.5.1 Set Analog Output Measurement Parameter and Scaling
Use the ASEL command to show or set the output measurement parameter ("quantity") and
the scaling of the analog output.
ASEL [quantity] [lowlimit highlimit]<cr>
quantity Quantity that is output on the analog channel: TDF or TFDA.
lowlimit The low limit of the output scaling in Celsius. Must be lower than high limit.
highlimit The high limit of the output scaling in Celsius. Must be higher than low limit.
Example (show current settings):
>asel
Quantity : TDF
Level Lo : -20
Level Hi : 40
>
Example (change output quantity to TDFA):
>asel tdfa
Quantity : TDFA
Saving settings...done
Level Lo : -20
Level Hi : 40
>
Example (change output to TDF, low limit to -10 and high limit to 30):
>asel tdf -10 30
Quantity : TDF
Saving settings...done
Level Lo : -10
Saving settings...done
Level Hi : 30
Saving settings...done
>
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4.5.2 Set Analog Output Error Notification
If the transmitter is malfunctioning, the analog output is set to a pre-defined level of 3.8 mA.
This overrides the normal measurement output of the channel. You can change the level, or
disable this behavior, using the AERR command:
AERR [on/off] [level]<cr>
on/o Enable (on) or disable (o) the analog output error notification.
level Analog output level, range 3.5 ... 30 mA.
Example (show current settings):
>aerr
Notification : ON
Error level 4-20 mA (mA): 3.800000
>
Example (disable analog output error notification):
>aerr off
>Notification : OFF
Saving settings...done
>
Example (enable analog output error
notification, set level to 21 mA):
>aerr on 21
Error level 4-20 mA (mA): 21.000000
Saving settings...done
>
The error output value is displayed only when there are minor electrical faults such as a
humidity sensor damage. When there is a severe device malfunction, the error output
value is not necessarily shown.
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4.6 Configuring Measurement Parameters
4.6.1 Set Pressure Value for Dew Point Calculation
The HUMICAPâ 180R sensor in the DMT132 is not very pressure-dependent. However, to
maximize the measurement accuracy, the pressure of the system must be known. The
pressure compensation value has been set at the factory according to the order form. You
can view and set a new value using the PRES command.
It is important to set the pressure compensation value accurately when the transmitter is
configured to output dew point temperature in atmospheric pressure (T
d/f
atm). For
standard dew point measurement (T
d/f
), it is enough to set an approximate pressure value
(±1 bar).
PRES [pp.ppppp]<cr>
pp.ppppp Absolute pressure (bara ) in the measuring point. Range 0 ... 20 bar.
Example:
>pres 1.01325
>Pressure (bar) : 1.01325
Saving settings...done
>
The pressure conversion
coecients from other pressure units to bars is given in the table
below.
Table 7 Pressure Conversion
Coecients
From To bar
a
PaN/m
2
0.00001
mmHg torr 0.001333224
inHg 0.03386388
mmH2O 0.00009806650
inH2O 0.002490889
atm 1.01325
at 0.980665
psi
a
0.06894757
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For example:
29.9213 = 29.9213 × 0.03386388 = 1.01325
Conversions from mmHg and inHg are defined at 0 °C and from mmH2O and inH2O at
4 °C.
You can also set the pressure compensation value when you connect the DMT132 to the
MI70 indicator. When using the MI70, the pressure unit is bara.
4.7 Serial Line Output Commands
4.7.1 Output a Reading Once
Use the SEND command to output a single measurement message. The output message is
sent for the measurement parameter that is currently selected using the ASEL command.
SEND<cr>
Example:
>send
Tdf= -0.80'C
>
4.8
Troubleshooting and Maintenance
Commands
4.8.1 Display Currently Active Errors
Use the ERRS command to display the currently active transmitter error codes. Possible
errors and their causes are listed in Table 8 (page 60).
ERRS<cr>
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Example (no errors active):
>errs
No errors
>
Example (Error E2 active):
>errs
Error: E2 Humidity sensor open circuit/not calibrated
>
4.8.2
Test Analog Output
The operation of the analog output can be tested with the ATEST command by forcing the
output to a given value which can then be measured with a calibrated multimeter. After
testing the output, give the ATEST command again to exit the test mode.
ATEST [mA]<cr>
mA Analog output value, range 0 ... 30 mA.
The output shows the test value of the analog output as well as diagnostic information that
may be useful to Vaisala Service Center if there is a problem with the analog outputs.
Example (enabling analog output test mode with 20 mA output):
>atest 20
20.000000, 536b
>
Example (disabling analog output test mode, resuming normal output):
>atest
>
4.8.3
Set LED Indicator Level
Use the ALARM command to change the dew point temperature above which the LED
indicator plug is lit. The currently measured measurement parameter is used. You can also
disable the LED indicator.
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ALARM [on/off] [limit]<cr>
on/o Enable (on) or disable (o) the LED indicator function.
limit Dew point temperature above which the LED indicator is lit. Range -20 ... 50 °C.
Example (show the current status of the LED indication):
>alarm
Alarm Led : OFF
Alarm level : 20.000000
>
Example (enable the LED indicator at dew point above 20 °C):
>alarm on 20
Alarm level : 20.000000
Saving settings...done
>
4.9 Calibration and Adjustment
Commands
Commands that have to do with calibration and adjustment on the serial line are described
below. For the calibration and adjustment procedures, see Calibration and Adjustment
(page 47).
4.9.1
Calibrate Humidity Measurement
Use the RHCAL command to perform a one-point or two-point humidity (RH) calibration.
RHCAL<cr>
When performing a one-point calibration, you need to place the transmitter in a single
humidity reference with RH < 50%. Run the command and enter the exact RH of the
reference after the measurement has stabilized. Exit the command by pressing the ESC key
before proceeding to the second point (see the first example below). To update the value,
press ENTER without inputting a value.
For two-point calibration, the first point requires a RH < 35% humidity reference, the second
point must be RH > 50%.
Example (one-point calibration):
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>rhcal
RH: 11.278554 Ref1 ? 11.3
Press any key when ready
OK
Saving settings...done
>
Example (two-point calibration):
>rhcal
RH: 11.278554 Ref1 ? 11.3
Press any key when ready
RH: 75.091213 Ref2 ? 75
OK
Saving settings...done
>
4.9.2
Calibrate Temperature Measurement
Use the CT command to perform a one-point or two-point temperature (T) calibration.
CT<cr>
When performing a one-point calibration, you need to place the transmitter in a single
temperature reference. Run the command and enter the exact temperature of the reference
after the measurement has stabilized. Exit the command by pressing the ESC key before
proceeding to the second point (see
first example below). To update the value, press ENTER
without inputting a value.
For two-point calibration, the second reference point must be at least 20 °C warmer than
the first. The measurement reading for the second point will appear when this requirement
is met.
Example (one-point calibration):
>ct
T 22.3104 Ref1 ? 22.3
Press any key when ready
OK
Saving settings...done
>
Example (two-point calibration):
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>ct
T 22.3104 Ref1 ? 22.3
Press any key when ready ...
T 44.9746 Ref2 ? 45
OK
>
4.9.3 Adjust Capacitance Measurement
Use the CRH command to perform a one-point or two-point correction to the capacitance
measurement of the transmitter. This command changes the oset and gain of the
measured capacitance, and therefore aects humidity measurement over the entire
temperature range.
This command should be used only when the HUMICAPâ sensor has been
replaced, or the measurement has drifted
significantly. For normal adjustment, use the
RHCAL command instead.
CAUTION!
CRH<cr>
When performing a one-point adjustment, you need to place the transmitter in a single
humidity reference with RH < 50%. Run the command and enter the exact RH of the
reference after the measurement has stabilized. Exit the command by pressing the ESC key
before proceeding to the second point (see the
first example below).
For two-point adjustment, the first point requires a RH < 50% humidity reference, the
second point must be RH > 50%. There must also be at least 30 percentage points of
dierence between the references. The measurement reading for the second point will
appear when this requirement is met.
Example: one-point adjustment
>crh
RH: 11.41200712 Ref1 ? 11.3
Press any key when ready
OK
>
Example: two-point adjustment
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>crh
RH: 11.41200712 Ref1 ? 11.3
Press any key when ready
RH: 74.72910210 Ref2 ? 75
OK
>
4.9.4 View User Adjustment Parameters
Use the L command to view the current user adjustment parameters that are aected by the
CRH, RHCAL, CT, and LI commands. This command is useful for checking the currently
applied correction.
L<cr>
The output values are as follows:
• Cp oset and gain: capacitance, adjusted using the CRH command.
• RH oset and gain: adjusted using the RHCAL command.
• T
oset and gain: adjusted using the CT command.
Example (shows default values, no user adjustment done):
>l
Cp offset : 0
Cp gain : 1
RH offset : 0
RH gain : 1
T offset : 0
T gain : 1
>
4.9.5
Set User Adjustment Parameters
Use the LI command to set the user adjustment parameters directly. This command is
useful for restoring the desired adjustments, and removing the eects of user adjustment
without having to perform the factory reset.
LI<cr>
After entering the command, you will be prompted to enter new values one at a time. Press
ENTER without giving a value to move to the next parameter.
Example (shows default values):
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>li
Cp offset : 0 ?
Cp gain : 1 ?
RH offset : 0 ?
RH gain : 1 ?
T offset : 0 ?
T gain : 1 ?
>
4.10 Other Commands
4.10.1 Display Command List
HELP<cr>
Example:
>help
?
AERR
ALARM
ASEL
ATEST
CALCS
CRH
CT
ERRS
FRESTORE
HELP
L
LI
PASS
PRES
RHCAL
RESET
SEND
SYSTEM
VERS
>
4.10.2
Reset Transmitter
When the RESET command is given, the transmitter will restart as if it had just been
powered on. All transmitter settings are retained.
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43
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RESET<cr>
Example:
>reset
DMT132 1.0.0 2011-02-03
Type "help" for command list
>
4.10.3 Restore Factory Settings
Use the FRESTORE command to restore the factory settings to the transmitter. All user
settings will be lost, and the transmitter will return to the factory calibrated state (user
adjustment is cleared).
FRESTORE<cr>
Example:
>frestore
Restoring factory defaults...done
Saving settings...done
>
If you have changed the HUMICAP® sensor yourself, be aware that the
FRESTORE command clears all of the user adjustment parameters, including the
capacitance oset and gain that are set by the CRH command.
If you want to avoid having to perform the capacitance adjustment procedure again,
record the adjustment parameters shown by the L command before performing the
FRESTORE command. You can afterwards restore the adjustment parameters using the
LI command.
See Set User Adjustment Parameters (page 42).
CAUTION!
If the HUMICAPâ sensor has been changed at a Vaisala Service Center, the factory
calibration has been updated to match the new sensor, and it will not be aected by the
FRESTORE command.
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5. Maintenance
5.1 Cleaning Transmitter
The body of the transmitter can be cleaned by wiping with a moistened lint-free cloth. Do
not immerse the transmitter in liquid and do not use cleaning agents or solvents.
Do not attempt to clean the filter or the sensor elements. If the filter is contaminated,
replace it with a new one.
5.2 Changing Filter
If the filter is contaminated, it should be replaced. New filters can be ordered from Vaisala
(order code 230602). Be careful when changing the filter, since it is easy to break the
sensors when the
filter is removed.
If the transmitter is installed in a pressurized chamber, always make sure
that the pressure of the chamber is equalized with the ambient pressure prior to
removing the transmitter. When the transmitter is removed for maintenance, cap the
hole with a capped nut. This way, the process can be running although the transmitter is
not in place. Plugs are available from Vaisala for ISO threaded connections (Vaisala order
code 218773) and NPT threaded connections (Vaisala order code 222507).
CAUTION!
When replacing the filter, note the following:
• Touching the filter with your fingers will also deposit oil and dirt on the filter, which may
aect the measurement. Always handle the filter with gloved hands.
• When installing the transmitter after a
filter change, inspect the sealing ring first. Use a
new one if the old ring is visibly damaged.
Figure 24 Opening the Filter
Chapter 5 – Maintenance
45
Page 48
1 42 3
Figure 25 Filter Structure
1 Sealing ring (replace if damaged)
2 Vaisala HUMICAP® 180R sensor and Pt1000 temperature sensor
3 Spring washer
4 Tube filter
Replace the filter as follows:
1. Turn the filter counterclockwise until it is loose.
2. Pull the filter straight out carefully; do not damage the sensors, and do not lose the
spring washer.
3. Take the new
filter, and insert it to the filter threads. The spring washer should be under
the filter. A new washer is not included with the filter, so reuse the old one.
4. Tighten the new
filter by turning it clockwise. Do not use tools to tighten the filter,
finger tightness is enough.
5.3
Changing Sensor
The user can replace the HUMICAPâ 180R sensor with a new one. The new sensor must be
of the HUMICAPâ 180R type. Do not attempt to use a dierent sensor type.
Replacing the sensor is repair maintenance, and it is not necessary in normal operation. If
the accuracy of the transmitter does not seem to be within
specification, it is more likely
that the transmitter is in need of calibration and adjustment, and not sensor replacement.
See Calibration and Adjustment (page 47).
1. Remove the filter as instructed in Changing Filter (page 45).
2. Remove the damaged sensor and insert a new one. Avoid touching the Pt1000 sensor.
Handle the new sensor by the plastic socket. DO NOT TOUCH THE SENSOR PLATE.
3. Attach a new
filter on the probe as instructed in Changing Filter (page 45).
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4. Perform a two-point calibration and adjustment using the CRH command as instructed
in Capacitance Adjustment (CRH) (page 55).
Figure 26 Removing the HUMICAPâ 180R Sensor
5.4
Calibration and Adjustment
The DMT132 is fully calibrated as shipped from the factory. The recommended calibration
interval is 2 years in refrigerator dryer applications. If the transmitter is used in the dry end
of the measurement range, calibration should be done every year. Calibration should also be
done if there is a reason to believe that the device is not within the accuracy
specifications.
For accurate calibration, disconnect the current loop from connector I for the duration of
the calibration. Power the transmitter using the USB service cable (Vaisala order code
219690) instead.
Ensure the pressure compensation setting matches the calibration environment before
starting measurements and possible adjustments. For instructions on checking and
setting the pressure compensation value, see Set Pressure Value for Dew Point Calculation
(page 36).
Chapter 5 – Maintenance
47
Page 50
If you have replaced the HUMICAPâ 180R sensor, you should adjust the capacitance
measurement of the transmitter using the serial command CRH. For normal calibration
and adjustment, use the RHCAL and CT commands.
Performing a good calibration takes some time and preparation. Read the Vaisala
Humidity Calibrator HMK15 User’s Guide before performing your first calibration with the
HMK15.
You can perform a simple field checking operation by comparing the readings of the DMT132
and the DM70 hand-held dew point meter with a calibrated reference probe.
To have the transmitter calibrated and adjusted by Vaisala, contact a Vaisala Service Center
or your local Vaisala representative.
More Information
‣
Field Check Using DM70 (page 48)
‣
Technical Support (page 67)
5.4.1
Field Check Using DM70
To check the accuracy of the DMT132 in the field, you need the following equipment:
• A fully charged MI70 indicator (the measurement display that is included in the DM70
and HM70 hand-held indicator products).
• A calibrated reference probe that is suitable for the intended measurement
environment and dew point range.
• DMP74A probe from the DM70 is the recommended choice, as it
oers the best
accuracy in the measurement range of the DMT132.
• All probes compatible with the DM70 and HM70 hand-held indicators may be used
as a reference.
• You can also use a second DMT132 transmitter.
• A connection cable between DMT132 and the MI70 indicator (Vaisala order code
219980).
• A reference environment with a stable dew point and temperature in a suitable range
for both devices. The normal measurement environment of the transmitter can also be
used, if it meets these criteria.
In the procedure below, the readings of the devices are checked individually. You can also
perform the
field check so that you connect the reference probe simultaneously with the
DMT132 you are checking. In this case, you need two of the connection cables if you are
using a DMT132 also as the reference probe.
Make sure that the measurements are made in the same pressure.
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Perform the check as follows:
1. Place the DMT132 in the reference environment (unless it is there already). You can
perform the check even if the DMT132 is currently being powered and used, as long as
there is no cable or LED indicator plug connected to connector II. However, external
powering is not needed when using the MI70 indicator with DMT132.
2. Connect the MI70 connection cable between the MI70 indicator and connector II of the
DMT132.
3. Turn on the MI70 indicator.
4. Check and adjust the environment settings if prompted. You can only change the
pressure compensation value that is used for dew point temperature calculation.
5. If the desired measurement parameters are not shown on the display, select them from
the Display > Quantities and units menu.
6. The Auto power
o function should be disabled on the MI70 indicator to prevent the
indicator from powering
o in the middle of the check. While waiting for the active
measurement to start, check the setting in the Settings > User interface menu, and
change if necessary.
7. Write down the T
d/f
reading after the measurement has stabilized.
8. Turn o the MI70 indicator and disconnect the DMT132.
9. Insert the reference probe to the measurement environment, and connect it to the MI70
indicator.
10. Turn on the MI70 indicator. Check and adjust the environment settings if prompted.
11. Wait for the reference probe to provide a stable reading, and compare it with the
reading from the DMT132.
The
dierence between the readings should be within the combined accuracy of the
reference probe and the DMT132 in the measured temperature and dew point. If the
dierence is more, the DMT132 is in need of adjustment.
You can send the DMT132 to be adjusted at Vaisala, or adjust the transmitter yourself.
Notes on using the MI70 indicator with the DMT132:
• If you disconnect the DMT132 while the MI70 indicator is on, the measurement
parameters will remain on the screen, but no measurement will be shown.
• Notification messages from the transmitter will appear in English even if the MI70 has
been set to another language.
More Information
‣
Technical Support (page 67)
‣
Humidity Calibration and Adjustment (RHCAL) (page 50)
Chapter 5 – Maintenance
49
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5.4.2 Humidity Calibration and Adjustment (RHCAL)
The procedure below describes a humidity measurement calibration and adjustment using
serial line commands and the Vaisala Humidity Calibrator HMK15. You can use the procedure
to do a one-point calibration
(oset) or a two-point calibration (oset and gain).
• To use the HMK15 humidity calibrator with the DMT132, you need the special cover set
for HMK15 (Vaisala order code 230914)
• One-point calibration requires a < 50 %RH reference
• Two-point calibration requires additionally a > 50 %RH reference, with over 30 %RH
dierence between the two points
Even though the transmitter outputs dew point, the humidity calibration procedure is
performed using relative humidity (RH) values. You can use the Humidity Calculator to
convert between dew point and relative humidity. The Humidity Calculator is available at:
www.vaisala.com/humiditycalculator.
Figure 27 Calibrating DMT132 Using HMK15 and USB Cable
1. Disconnect the cable from connector I of the DMT132 (if connected).
2. Connect the USB cable to connector II on the DMT132, and to a USB port on your PC.
3. Start a terminal application and set the service port connection settings (19200 8 N 1).
Remember to check which COM port the USB cable is using.
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4. Verify that the connection works by giving the ? command:
>?
If the transmitter does not respond with device information:
• Check your serial line settings and cable connections
• Reconnect the USB cable, restart the terminal application, and try again
5. When your serial connection is working, use the L command to see the current user
adjustment parameters.
Write down the RH
oset and gain values so you can restore them manually using the
LI command, if necessary.
>l
6. Use the ERRS command to see that no errors are active:
>errs
7. Install the HMK15 calibrator fitting over the LiCl salt chamber of the humidity calibrator
(11 %RH).
Make sure it sits tightly over the salt chamber.
8. Insert the DMT132 into the chamber. Do not remove the
filter.
Make sure all unused holes are plugged and the transmitter is installed tightly on the
thread.
9. Give the RHCAL command.
The output from the command shows the currently measured RH value, and prompts
you to enter the value of the
first reference (Ref1). This is the reference on the dry end,
which produces the oset correction for the measurement.
>rhcal
RH: 10.840536 Ref1 ?
10. Wait for 20 ... 40 minutes for the reading to stabilize.
Press ENTER without typing anything to update the value shown by the RHCAL
command.
RH: 10.890510 Ref1 ?
RH: 10.920197 Ref1 ?
RH: 10.930460 Ref1 ?
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11. When the measurement shown by RHCAL is stable, you can either apply the correction
or exit the procedure:
• To apply the correction, press ENTER one last time to update the value, type 11 and
press ENTER again (assuming you are using the HMK15 and the LiCl salt).
• To exit the RHCAL command without adjusting the measurement, press the ESC key
and exit this procedure.
12. If you only want to perform a one-point calibration (oset correction), press the ESC
key after entering the correction. The RHCAL command will exit, and you can move to
step 16.
RH: 10.950116 Ref1 ? 11
Press any key when ready
>
To continue with the calibration of the wet end (gain correction), press ENTER.
13. Insert the DMT132 in the NaCl salt chamber (75 %RH). Make sure the salt chamber is
sealed and the transmitter sits tightly.
14. Wait for 20 ... 40 minutes for the reading to stabilize. Press ENTER without typing
anything to update the value shown by the RHCAL command.
RH: 75.251050 Ref2 ?
RH: 75.200621 Ref2 ?
RH: 75.198200 Ref2 ?
15. To apply the correction, press ENTER one last time to update the value, type 75 and
press ENTER again (assumes you are using the HMK15 and the NaCl salt).
RH: 75.175200 Ref2 ? 75
OK
Saving settings...done
>
The RHCAL command is now finished and both adjustments have been applied.
16. Use the L command to verify that the new user adjustment parameters are in use:
>l
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17. Use the SEND command to verify that the measurement is OK:
>send
Tdf= -9.33'C
>
5.4.3 Temperature Calibration and Adjustment (CT)
The following procedure describes a temperature (T) measurement calibration and
adjustment using serial line commands. You can use the procedure to do a one-point
calibration (oset) or a two-point calibration (oset and gain). For two-point calibration, the
second reference point must be at least 20 °C warmer than the
first.
1. Disconnect the cable from connector I of the DMT132 (if connected).
2. Connect the USB cable to connector II on the DMT132, and to a USB port on your PC.
3. Start a terminal application and set the service port connection settings (19200 8 N 1).
Remember to check which COM port the USB cable is using.
4. Verify that the connection works by giving the ? command:
>?
If the transmitter does not respond with device information:
• Check your serial line settings and cable connections.
• Reconnect the USB cable, restart the terminal application, and try again.
5. When your serial connection is working, use the L command to see the current user
adjustment parameters.
Write down the T
oset and gain values so you can restore them manually using the LI
command, if necessary.
>l
6. Use the ERRS command to see that no errors are active:
>errs
7. Insert the transmitter in the temperature reference.
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8. Give the CT command.
The output from the command shows the currently measured T value, and prompts you
to enter the value of the first reference (Ref1). This is the reference on the colder end,
which produces the oset correction for the measurement.
>ct
T 21.0947 Ref1 ?
9. Wait for 20 ... 40 minutes for the reading to stabilize. Press ENTER without typing
anything to update the value shown by the CT command.
T 22.1298 Ref1 ?
T 22.1317 Ref1 ?
T 22.1576 Ref1 ?
10. When the measurement shown by CT is stable, you can either apply the correction or
exit the procedure:
• To apply the correction, press ENTER one last time to update the value, type the
temperature of the reference in degrees Celcius, and press ENTER.
• To exit the CT command without adjusting the measurement, press the ESC key and
exit this procedure.
11. If you only want to perform a one-point calibration
(oset correction), press the ESC
key after entering the correction.
The CT command will exit, and you can move to step 14.
>ct
T 22.1601 Ref1 ? 22
Press any key when ready
To continue with the calibration of the warmer end (gain correction), press ENTER.
12. Insert the transmitter in the second temperature reference and wait for 20 ... 40
minutes for the reading to stabilize.
The measurement reading for the second point will appear when the measured
temperature is at least 20 °C warmer than the
first reference point.
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13. Type the temperature of the second reference point and press ENTER to apply the
correction.
T 44.9847 Ref2 ? 45
OK
Saving settings...done
>
The CT command is now finished and both adjustments have been applied.
14. Use the L command to verify that the new user adjustment parameters are in use:
>l
15. Use the SEND command to verify that the measurement is OK:
>send
Tdf= -1.25'C
>
5.4.4
Capacitance Adjustment (CRH)
Adjusting the capacitance measurement aects measurement accuracy
across the entire temperature range. This command should be used only when the
sensor has been replaced, or the measurement has drifted
significantly. After sensor
change, you must perform the two-point capacitance adjustment. For normal
adjustment, use the RHCAL command instead.
CAUTION!
Write down the current capacitance adjustment parameters (visible with the
L command) so that you can restore them manually if necessary. Be aware that if you
revert the transmitter to factory settings using the FRESTORE command, you will clear
all of the user adjustment parameters, including the capacitance
oset and gain that are
set by the CRH command. See Restore Factory Settings (page 44).
CAUTION!
The procedure below adjusts the capacitance measurement of the transmitter using the
serial line commands and the Vaisala Humidity Calibrator HMK15. You can use the procedure
to do a one-point adjustment
(oset) or a two-point adjustment (oset and gain).
• One-point adjustment requires a < 50 %RH reference.
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• Two-point adjustment requires additionally a > 50 %RH reference, with over 30 %RH
dierence between the two points.
1. Disconnect the cable from connector I of the DMT132 (if connected).
2. Connect the USB cable to connector II on the DMT132, and to a USB port on your PC.
3. Start a terminal application and set the service port connection settings (19200 8 N 1).
Remember to check which COM port the USB cable is using.
4. Verify that the connection works by giving the ? command:
>?
If the transmitter does not respond with device information:
• Check your serial line settings and cable connections
• Reconnect the USB cable, restart the terminal application, and try again.
5. When your serial connection is working, use the L command to see the current user
adjustment parameters. Write down the Cp
oset and gain values so you can restore
them manually using the LI command, if necessary.
>l
6. Use the ERRS command to see that no errors are active:
>errs
7. Install the HMK15 calibrator fitting over the LiCl salt chamber of the humidity calibrator
(11 %RH). Make sure it sits tightly over the salt chamber.
8. Insert the DMT132 into the chamber. Do not remove the
filter.
Make sure all unused holes are plugged and the transmitter is installed tightly on the
thread.
9. Give the CRH command.
The output from the command shows the currently measured RH value, and prompts
you to enter the value of the
first reference (Ref1). This is the reference on the dry end,
which produces the
oset correction for the measurement.
>crh
RH: 11.39800112 Ref1 ?
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10. Wait for 20 ... 40 minutes for the reading to stabilize. Press ENTER without typing
anything to update the value shown by the CRH command.
RH: 11.39800112 Ref1 ?
RH: 11.38377201 Ref1 ?
RH: 11.37988329 Ref1 ?
11. When the measurement shown by CRH is stable, you can either apply the correction or
exit the procedure:
• To apply the correction, press ENTER one last time to update the value, type 11 and
press ENTER again (assuming you are using the HMK15 and the LiCl salt).
• To exit the CRH command without adjusting the measurement, press the ESC key
and exit this procedure.
12. If you only want to perform a one-point adjustment
(oset correction), press the ESC
key after entering the correction.
The CRH command will exit, and you can move to step 16.
RH: 11.35423321 Ref1 ? 11
Press any key when ready
>
To continue with the adjustment of the wet end (gain correction), press ENTER.
13. Insert the DMT132 in the NaCl salt chamber (75 %RH). Make sure the salt chamber is
sealed and the transmitter sits tightly.
14. Wait for 20 ... 40 minutes for the reading to stabilize. Press ENTER without typing
anything to update the value shown by the CRH command.
RH: 74.87782214 Ref2 ?
RH: 74.89157890 Ref2 ?
RH: 74.91556023 Ref2 ?
15. To apply the correction, press ENTER one last time to update the value, type 75 and
press ENTER again (assumes you are using the HMK15 and the NaCl salt).
RH: 74.95221002 Ref2 ? 75
OK
>
The CRH command is now
finished and both adjustments have been applied.
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16. Use the L command to verify that the new user adjustment parameters are in use, and
write them down for later reference:
>l
17. Use the SEND command to verify that the measurement is OK:
>send
Tdf= -9.33'C
>
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6. Troubleshooting
6.1 Typical Problems
If you have a problem with the DMT132,
first read the following sections concerning the
behavior and error indications of the transmitter:
• Error Codes (page 60)
• Error State (page 59)
Typical causes of errors include the following:
• Incorrect supply voltage
• Incorrect wiring
• Physical damage to the transmitter, especially the sensor elements
• Contamination or condensation on the sensors
Some problems can be solved by simply resetting the transmitter. You can reset the
transmitter by disconnecting the power or issuing the RESET command using the service
port.
If resetting does not help, and if the problem is related to user calibration or transmitter
software, you can restore the factory
configuration of the transmitter by issuing the
FRESTORE command.
If you cannot solve the problem and return the transmitter to the normal state, please
contact Vaisala technical support.
If repair is needed, you can have the transmitter serviced by a Vaisala Service Center.
More Information
‣
Technical Support (page 67)
6.2
Error State
If the voltage supplied to the DMT132 is too low for reliable operation, or there is some
serious problem that prevents measurement, the DMT132 will enter an error state. The error
state is indicated by the following:
• Analog current output is set to the error level (default is 3.8 mA)
• If the LED indicator plug option is installed, the LED is blinking
• Serial line outputs asterisk characters "*" instead of measurement data for the SEND
command
For example:
>send
Tdf= ***.**'C
>
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• The ERRS command returns the currently active error code(s).
For example:
>errs
Error: E2 Humidity sensor open circuit/not calibrated
>
The analog output levels for the error state are configurable using the AERR command;
see Set Analog Output Error Notification (page 35).
6.3 Error Codes
The transmitter has error codes that can be displayed on the serial line using the ERRS
command. See Display Currently Active Errors (page 37).
Table 8 Error Codes
Error Code Error Message Possible Cause(s)
E1 Temperature sensor open
circuit/not calibrated
• Temperature sensor damaged
• Temperature sensor short circuit
• Temperature sensor missing
E2 Humidity sensor open circuit/not
calibrated
• Condensation on humidity sensor
• Humidity sensor damaged
• Humidity sensor short circuit
• Humidity sensor missing
E5 Capacitance out of range • Condensation on humidity sensor
• Humidity sensor damaged
E6 Program checksum error Internal error
E7 Parameter storage checksum error Internal error
E9 Sensor coecient checksum error Internal error
E10 Current settings checksum error Internal error
E11 Factory settings checksum error Internal error
E12 Temperature sensor values out of
range
• Temperature sensor damaged
• Temperature sensor missing
E14 MeasTask not calculating (ATEST) This error may occur when the analog output is in
test mode.
See Test Analog Output (page 38).
E16 Default settings not found Internal error
E17 RH reading too high Internal error
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Error Code Error Message Possible Cause(s)
E18 RH reading too low Internal error
E20 Log corrupted Internal error
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7. Technical Data
Table 9 Measurement Performance
Property Description/Value
Dew Point
Measurement range -30 ... +50 °C (-22 ... +122 °F) T
d
Accuracy at +20 °C (+68 °F)
±1 °C for -3 ... 20 °C (+26.6 ... +68 °F) T
d
1)
±2 °C for -15 ... -3 °C (+5 ... +26.6 °F) T
d
1)
See accuracy graph below
Typical Response Time at 20 °C (+68 °F) Gas Temperature and 1 Bar Pressure
-14 → +3 °C (+7 → +37 °F) T
d
17 s (63 %)
40 s (90 %)
+3 → -14 °C (+37 → +7 °F) T
d
33 s (63 %)
85 s (90 %)
Calculated Variables
Dew point converted to atmospheric pressure T
d/f
atm
1) When dew point is below 0 °C (+32 °F), the transmitter outputs frost point.
Dew point temperature (°C)
0 20
20
0
10
30
-10
-20
-30
-10 10 30 40 50 60
Temperature of measured gas (°C)
50
40
60
Accuracy
±1 °C
Accuracy
±2 °C
-20
Accuracy
not specified
Figure 28 Accuracy Over Temperature Range
Table 10 Operating Environment
Property Description/Value
Operating temperature -30 ... +50 °C (-22 ... +122 °F)
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Property Description/Value
Operating pressure 0 ... 20 bar
Relative humidity 0 ... 100 %RH
Sample flow rate No eect on measurement accuracy
Measured gases Non-corrosive gases
EMC compliance EN61326-1, Industrial Environment
Table 11 Outputs
Property Description/Value
Analog output (scalable) 4 ... 20 mA, 2-wire
Resolution for current output 0.002 mA
Accuracy of analog outputs at +20 °C ±0.05 % full scale
Typical temperature dependence ±0.005 % of full scale/ °C
Connector 4-pin M8 (IEC 60947-5-2)
LED indication available for defined dew point limit/error state indication
RS-485 serial line for service use
Table 12 Mechanical Specifications
Property Description/Value
Sensor Vaisala HUMICAPâ 180R
Recommended calibration interval
(in refrigerant dryer application)
2 years
Mechanical connection G1/2" ISO
Operating voltage 10 .... 28 VDC
External load Max. 100 Ω for supply voltages < 20 VDC
Max. 500 Ω for supply voltages 20 ... 28 VDC
Weight 65 g (2.3 oz)
Housing material PPS + 40 % GF
IP rating IP65 (NEMA 4)
Storage temperature range -40 ... +80 °C (-40 ... +176 °F)
Start-up time 3 s
Table 13 Output Cable Specifications
Property Description/Value
Connector Straight, molded M8 female (IEC 60947-5-2)
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Property Description/Value
Color Black
Number of contacts 4
Conductors
0.25 mm2 (× 4) (0.00039 in2 (× 4))
Insulation PVC
Cable diameter 5.0 mm (0.2 in)
Protection class IP67 / NEMA 4
Wire color code EN50044
7.1 Dimensions
2.5
12
4580.5
125.5
6
36
G1/2" ISO 228-1
33
AW
30
R19.5
Figure 29 DMT132 Dimensions
20.5
40
26
NPT 1/2"
AW 27
Figure 30 Dimensions with NPT Adapter and LED Plug
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7.2 Spare Parts and Accessories
Table 14 Spare Parts and Accessories
Item Order Code
Tube filter 230602
Special cover set for HMK15
(calibrator fitting DMT132 and HMP60)
230914
NPT Adapter 210662SP
Sample cells DMT242SC, DMT242SC2, DSC74, DSC74B, DSC74C,
DMCOIL
Duct installation flange DM240FA
Cables (several lengths available) HMP50Z032, HMP50Z300SP, HMP50Z500SP,
HMP50Z1000SP
Loop powered external display 226476
USB service cable 219690
Connection cable to DM70/HM70 219980
LED plug 230388
ISO 1/2" plug 218773
NPT 1/2" plug 222507
Sealing ring set (3 pcs U-seal) 221525SP
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Warranty
For standard warranty terms and conditions, see www.vaisala.com/warranty.
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.
Technical Support
Contact Vaisala technical support at helpdesk@vaisala.com. Provide at least the following
supporting information:
• Product name, model, and serial number
• Name and location of the installation site
• Name and contact information of a technical person who can provide further
information on the problem
For more information, see www.vaisala.com/support.
Recycling
Recycle all applicable material.
Follow the statutory regulations for disposing of the product and packaging.
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www.vaisala.com
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