USER'S GUIDE Vaisala HUMICAP® Humidity and Temperature Transmitter Series HMT120

USER'S GUIDE

Vaisala HUMICAP® Humidity and

Temperature Transmitter Series

HMT120

M211244EN-A

PUBLISHED BY

Vaisala Oyj

P.O. Box 26

FI-00421 Helsinki

Finland

Phone (int.): +358 9 8949 1

Fax:

Visit our Internet pages at www.vaisala.com

.

+358 9 8949 2227

© Vaisala 2010

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

The contents are subject to change without prior notice.

Please observe that this manual does not create any legally binding obligations for

Vaisala towards the customer or end user. All legally binding commitments and agreements are included exclusively in the applicable supply contract or Conditions of

Sale.

________________________________________________________________________________

Table of Contents

CHAPTER 1

GENERAL INFORMATION ............................................................................ 7

About This Manual ................................................................... 7

Contents of This Manual ....................................................... 7

Version Information ............................................................... 8

Related Manuals ................................................................... 8

Documentation Conventions ................................................. 8

Safety......................................................................................... 9

ESD Protection ......................................................................... 9

Recycling .................................................................................. 9

Regulatory Compliances ....................................................... 10

Patent Notice .......................................................................... 10

Trademarks ............................................................................. 10

License Agreement ................................................................ 10

Warranty .................................................................................. 11

CHAPTER 2

PRODUCT OVERVIEW................................................................................ 13

Introduction to the HMT120 Humidity and Temperature

Transmitter.............................................................................. 13

Accessories ......................................................................... 14

Fixed and Remote Probe Models ....................................... 14

Optional Display .................................................................. 14

Interchangeable Probe........................................................ 14

Constant Output Probe ....................................................... 15

Transmitter Components..................................................... 16

CHAPTER 3

INSTALLATION............................................................................................ 17

Mounting ................................................................................. 17

Wall Mounting ..................................................................... 17

Installation with Rain Shield ................................................ 18

Installation with Radiation Shield ........................................ 19

Duct Installation Kit ............................................................. 20

Probe Assembly with Duct Installation Kit ..................... 21

Drilling Instructions for Duct Installation Kit ................... 21

Probe Mounting Flange....................................................... 22

Probe Mounting Clamp ....................................................... 23

Connections............................................................................ 24

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CHAPTER 4

OPERATION .................................................................................................27

Using the Service Port ...........................................................27

Installing the Driver for the USB Cable................................27

Terminal Application Settings..............................................28

List of Serial Commands .......................................................30

Device Information and Status..............................................31

Show Device Information ....................................................31

Set/Show Available Quantities ............................................32

Set/Show Calibration Date ..................................................32

Set/Show Calibration Information........................................33

Show Analog Output Status ................................................34

Show System Information ...................................................35

Show Firmware Version ......................................................35

Serial Line Output Commands ..............................................35

Start Continuous Outputting ................................................35

Stop Continuous Outputting ................................................36

Set/show Output Interval .....................................................36

Output a Reading Once.......................................................36

Calibration Commands ..........................................................37

Calibrate Humidity Measurement ........................................37

Restore Probe RH Factory Calibration................................38

Calibrate Temperature Measurement .................................38

Restore Probe T Factory Calibration...................................39

Calibrate Analog Output ......................................................39

Configuring Serial Line Operation ........................................40

Set/Show Serial Line Settings .............................................40

Set/Show Terminal Echo.....................................................40

Set/Show Serial Interface Mode..........................................41

Configuring Measurement Parameters ................................41

Set/Show Environmental Parameters .................................41

Configuring Analog Output ...................................................42

Set/show Analog Output Error Levels .................................42

Set/show Analog Output Quantity and Scaling ...................42

Test Analog Outputs............................................................44

Other Commands ...................................................................45

Set/show Displayed Quantities............................................45

Set/show Output Formatting................................................46

Display Command List ........................................................47

Display Active Errors ...........................................................47

Save Changed Settings.......................................................47

Restore Saved Settings.......................................................48

Reset Transmitter ................................................................48

Restore Factory Settings .....................................................48

Set/show Output Unit...........................................................49

CHAPTER 5

MAINTENANCE............................................................................................51

Replacing the HUMICAP

®

Sensor .........................................51

Fixed and Remote Probe Models........................................51

Removing and Fastening the Probe .....................................52

Fixed Probe Model ..............................................................52

Remote Probe Model ..........................................................53

Calibration and Adjustment...................................................54

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HMT120 Push-Button Calibration ....................................... 54

Humidity and Temperature Adjustment .............................. 55

Adjustment with HM70 ........................................................ 58

Field Checking and Adjustment Using a Calibrated

Reference Probe ............................................................ 59

One-Point Adjustment Using a Calibrator...................... 59

Two-Point Adjustment Using a Calibrator ...................... 60

LiCl-NaCl Adjustment..................................................... 61

Temperature Field Check and Adjustment by Using a

Calibrated Reference Probe .......................................... 62

Adjustment with HMI41 ....................................................... 63

Connections and Selecting the Calibrator Function....... 64

Offset and Gain Adjustments ......................................... 65

HMI41 as a Reference Meter.................................... 66

HMI41 as a Terminal................................................. 67

Troubleshooting ............................................................. 68

Analog Output Tests .............................................................. 69

CHAPTER 6

TROUBLESHOOTING ................................................................................. 71

Error Codes............................................................................. 71

Solving Typical Problems ..................................................... 72

Analog Output Error Notification.......................................... 73

Technical Support .................................................................. 73

CHAPTER 7

TECHNICAL DATA ...................................................................................... 75

Specifications ......................................................................... 75

Options and Accessories ...................................................... 77

Transmitter Dimensions ........................................................ 78

APPENDIX A

CALCULATION FORMULAS ...................................................................... 81

Dewpoint Temperature .......................................................... 82

Dew/frostpoint Temperature ................................................. 82

Mixing Ratio ............................................................................ 83

Absolute Humidity.................................................................. 83

Enthalpy .................................................................................. 83

Saturation Vapor Pressure .................................................... 84

Water Vapor Pressure............................................................ 85

INDEX ........................................................................................................... 87

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List of Figures

Figure 1

HMT120 Components ..............................................................16

Figure 2

HMT120 Wall Mounting ............................................................17

Figure 3

HMT120 Installation with Rain Shield.......................................18

Figure 4

Installation of the Probe with Radiation Shield .........................19

Figure 5

Probe Installation with the Duct Installation Kit ........................20

Figure 6

Assembly of the Probe with Duct Installation Kit ......................21

Figure 7

Drilling Instructions ...................................................................21

Figure 8

Optional Probe Mounting Flange..............................................22

Figure 9

Optional Probe Mounting Clamp ..............................................23

Figure 10

HMT120 Component Board......................................................24

Figure 11

Isolated Current-Loop Wiring....................................................25

Figure 12

PuTTY Terminal Application.....................................................29

Figure 13

Removing the Humidity Probe (Fixed Probe Model) ................52

Figure 14

Removing the Humidity Probe (Remote Probe Model) ............53

Figure 15

Adjustment Buttons ..................................................................54

Figure 16

Location of the MI70 Probe and Cable Connector Ports..........58

Figure 17

Example of the MI70 Adjustment Menu ...................................60

Figure 18

Example of the MI70 Adjustment Mode Graph Display ...........60

Figure 19

Location of the HMI41 Calibration Connector ..........................63

Figure 20

HMT120 Output Current Measurement....................................69

Figure 21

Dimensions of the Fixed Probe Model in mm (inches).............78

Figure 22

Dimensions of the Remote Probe Model in mm (inches) .........79

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List of Tables

Table 1

Manual Revisions ....................................................................... 8

Table 2

Related Manuals ........................................................................ 8

Table 3

Wiring Table ............................................................................. 25

Table 4

Default Serial Interface Setting ................................................ 28

Table 5

Serial Port Commands ............................................................. 30

Table 6

Common Problems During Adjustment and Their Remedies .. 68

Table 7

Error Codes and Texts ............................................................. 71

Table 8

Troubleshooting Table.............................................................. 72

Table 9

Relative Humidity Measurement Specifications ....................... 75

Table 10

Temperature Measurement Specifications .............................. 75

Table 11

Operating Environment Specifications ..................................... 76

Table 12

Inputs and Outputs ................................................................... 76

Table 13

Mechanical Specifications ........................................................ 76

Table 14

Options and Accessories.......................................................... 77

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Chapter 1 ________________________________________________________ General Information

CHAPTER 1

GENERAL INFORMATION

This chapter provides general notes for the manual and HMT120.

About This Manual

This manual provides information for installing, operating, and maintaining the Humidity and Temperature Transmitter HMT120.

Contents of This Manual

This manual consists of the following chapters:

and HMT120.

- Chapter 2, Product Overview, provides general information about the

Vaisala Humidity and Temperature Transmitter HMT120

- Chapter 3, Installation, provides information on the installation of

Vaisala Humidity and Temperature Transmitter HMT120

- Chapter 4, Operation, contains information that is needed to operate the HMT120.

- Chapter 5, Maintenance, provides information that is needed in basic maintenance of the product.

- Chapter 6, Troubleshooting, describes error messages and analog output error behavior, introduces some common problems, their probable causes and remedies and provides contact information for technical support

- Chapter 7, Technical Data, provides the technical data of the product.

- Appendix A, Calculation Formulas, contains the formulas used for the calculated output quantities.

- INDEX

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Version Information

Table 1 Manual Revisions

Manual Code

M211244EN-A

Description

November 2010. First version.

Related Manuals

Table 2 Related Manuals

Manual Code

M210185EN

M210297EN

Manual Name

Humidity Calibrator HMK15 User's Guide

Hand-held Humidity and Temperature Meter

HM70 User's Guide

M211060EN

Operating Manual

HMP60/110 Probe User's Guide

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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Safety

The Humidity and Temperature Transmitter HMT120 delivered to you has been tested for safety and approved as shipped from the factory. Note the following precautions:

CAUTION Do not modify the unit. Improper modification can damage the product or lead to malfunction.

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

Vaisala HUMICAP® Humidity and Temperature Transmitter Series

HMT120 is in conformity with the provisions of the following EU directives:

- 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 55022 + Am1: Information technology equipment – Radio disturbance characteristics – Limits and methods of measurement.

Patent Notice

The HMT120 is protected by the following patents and their corresponding national rights:

Finnish patent 98861, French patent 6650303, German patent 69418174,

Japanese patent 3585973, UK patent 0665303, U.S. patent 5607564.

Trademarks

HUMICAP



is a registered trademark of Vaisala Oyj.

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.

10 __________________________________________________________________ M211244EN-A


Warranty

For certain products Vaisala normally gives a limited one-year warranty.

Visit our Internet pages for more information and our standard warranty terms and conditions: www.vaisala.com/services/warranty.html

.

For certain products Vaisala normally gives a limited one-year 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.

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Chapter 2 __________________________________________________________ Product Overview

CHAPTER 2

PRODUCT OVERVIEW

Thank you for choosing the Vaisala HUMICAP® Humidity and

Temperature Transmitter Series HMT120. This chapter introduces you to its features.

The Vaisala range of relative humidity measurement instruments covers all the applications from ventilation to process control in demanding conditions. For more information about other Vaisala relative humidity instruments, please contact your Vaisala representative or visit www.vaisala.com

.

Introduction to the HMT120 Humidity and

Temperature Transmitter

The Vaisala HUMICAP

®

Humidity and Temperature Transmitter Series

HMT120 measures relative humidity and temperature and converts it to analog current loop outputs. Other quantities, such as dewpoint (Td) can be calculated from the basic RH and T values according to the device configuration. HMT120 is powered with a 10 ... 30 VDC external loop voltage (20 ... 30 VDC when R

L

<500 ohms) and it outputs two analog current signals with nominal 4 ... 20 mA range.

HMT120 transmitter's output quantities are configurable. Available quantities for outputs are limited to two at the time. These two quantities can be used freely at any outputs (display, service port and analog current loop outputs).

Available quantities are RH, T, Td, Td/f, a, x, h, Tw, pws, and pw.

The default output quantities are set at the factory during order time.

These factory preset quantity selections can be changed afterwards via service port if necessary.

The HMT120T and HMT120H models are single-parameter transmitters.

The only output quantity of HMT120T is temperature. The output of the

HMT120H can be configured to be any one of the humidity-related quantities (RH, Td, Td/f, a, x, h, Tw, pws and pw).

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Accessories

The following accessories are optionally available:

- Duct installation kit

- Rain/solar radiation shield installation kit (for pole installation)

- Probe mounting flange

- Probe mounting clamp

- Constant output probe (HMP1100REF, gives constant RH and

T values)

Fixed and Remote Probe Models

The HMT120 is available either with a fixed probe directly attached to the transmitter housing or a remote probe with different (3/5/10 m) cable lengths. All extension cables can be easily cascaded in order to obtain

longer reach; see Options and Accessories on page 77.

NOTE

Optional Display

The HMT120 is also available with an optional graphical 128*64 pixel resolution LCD display. The display shows the measurement results of selected parameters in selected units (defined at the time of ordering).

The parameters are displayed simultaeously at two separate rows on the display.

Interchangeable Probe

The HMP110 relative humidity probe used in the HMT120 transmitter is fully interchangeable. You can easily remove the probe and replace it with a new one without having to adjust the transmitter. You have the following options when purchasing a new probe from Vaisala:

- Order a new probe and keep your current one.

- Order a new probe and return the old one to Vaisala (replacement probe).

Only probes that have a compatible digital output (VDIGI mode) can be used with HMT120 transmitter. Compatible probes have the letter "V" as the first letter in their order code. The order code is written on the probe.

14 __________________________________________________________________ M211244EN-A

Chapter 2 __________________________________________________________ Product Overview

Constant Output Probe

NOTE

The constant output probe is a testing accessory that can be used to check the transmitter's functions and measurement signal transfer chain all the way to the control system. The constant output probe does not measure humidity and temperature; instead, it outputs constant humidity and temperature readings.

The values output by the constant output probe are specified when ordering. These values are written on an additional label on the probe body.

The procedure for using the constant output probe is simply to replace the original probe for the duration of the testing:

1. Disconnect the normal probe from transmitter.

2. Connect the constant output probe to the transmitter.

3. Check that all used outputs (analog, display, serial line) show the correct measurement values.

4. After checking the outputs, disconnect the constant output probe and reconnect the original probe.

The transmitter goes to the error state for a short time when the probe is changed. This is normal.

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Transmitter Components

Figure 1 below illustrates the main features of HMT120. On the left is a

remote probe model without display, and on the right is a fixed probe model with the optional display. The numbers and arrows indicate the main components of the transmitters.

Figure 1 HMT120 Components

The following numbers refer to Figure 1 above:

1007-001

2 = Cable bushing: cable gland, cable grommet, or conduit fitting.

5 = Plastic grid filter

See section Options and Accessories on page 77 for accessory parts and

their numbers.

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Chapter 3 _______________________________________________________________ Installation

CHAPTER 3

INSTALLATION

Mounting

Wall Mounting

1. Open the HMT120 cover by pushing the releasing button at the bottom of the transmitter housing and gently pulling the bottom part of the cover towards yourself.

2. Make sure that the HMT120 Humidity and Temperature

Transmitter is correctly aligned and attach it directly to the wall with up to four screws (not included in the package).

1011-149

Figure 2 HMT120 Wall Mounting

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NOTE

Select the size and type of the fastening screws according to the wall material (for example, wood or stone). Even though using all four screws is strongly recommended, the HMT120 enclosure fastening holes are initially covered with a thin plastic membrane, so less than four screws could be also be used without sacrificing the ingress protection (IP) class of the enclosure. The diameter of the fastening screws is typically between 3.5 and 4mm.

Installation with Rain Shield

The installation kit with rain shield includes a metal mounting plate and a rain shield for the transmitter. Vaisala order code: 215109.

Figure 3 HMT120 Installation with Rain Shield

1011-150

1. Fasten the metal mounting plate to the wall or pole with screws

(see Figure 3 above). Note the arrow on the mounting plate. Attach

the mounting plate with the arrow pointing upwards.

2. Drill holes for the screws in the HMT120 frame, and fasten

HMT120 Humidity and Temperature Transmitter to the metal mounting plate with four (M4) screws.

3. Fasten the rain shield to the metal mounting plate with two (M6) mounting screws.

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Installation with Radiation Shield

DTR502 with probe installation kit includes a rain/solar radiation shield

DTR502 and a plastic installation support for the humidity probe. Vaisala order code: DTR502B. If you already have the DTR502 shield and need only the installation support for the probe, it is available with Vaisala order code 210623.

1. Fasten the probe to the installation support with two cable ties

(items 3 and 4 in Figure 4 below).

2. Insert and attach the support to the radiation shield by tightening

the plastic nut (item 2 in Figure 4).

3. Attach the entire radiation shield/probe assembly to a pole mast

(pole mast diameter: 30 ... 60 mm/1.2 ... 2.3") with the U-bolt and

support arm. See Figure 4.

1

6

2

5

3

4

0505-248

Installation of the Probe with Radiation Shield Figure 4


3, 4 = Cable tie

5 = Adapter DRW212054 (installation support)

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Duct Installation Kit

The duct installation kit includes a plastic pipe with a flange (Vaisala order code: 215619). To install the HMP110 probe with the duct installation kit, drill a hole to the duct wall, assemble the probe to the duct installation kit, slide the probe head through the hole, and attach the

flange to the duct wall with four screws. See page 21 for details.

24

1

L

Figure 5

The following explanations refer to Figure 5 above:

0505-176

Probe Installation with the Duct Installation Kit

Distance L can be adjusted and locked in place with the tension screw.

20 __________________________________________________________________ M211244EN-A


Probe Assembly with Duct Installation Kit

1

2

3

0505-177

Figure 6 Assembly of the Probe with Duct Installation Kit


2 = Duct installation kit

1. Slide the probe cable through the duct installation kit plastic pipe.

2. Attach the probe cable to the HMP110 Humidity Probe.

3. Attach probe assembly to the duct.

Drilling Instructions for Duct Installation Kit

Ø24

Ø3.

2

3

2

1

0505-178

Figure 7 Drilling Instructions


3 = HMP110 assembled in duct installation kit plastic pipe

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Drill the holes for the duct installation kit as follows:

1. Use a 24-mm drill bit to drill a hole to the duct wall for the humidity probe.

2. Drill holes for the duct installation kit mounting screws around the hole in a square arrangement, 42 mm apart from each other. Use a

3.2-mm drill bit to drill the holes for the mounting screws (four

ST4.2×16-C-Z DIN 7981 screws).

Probe Mounting Flange

The probe mounting flange (Vaisala order code: 226061) is a general purpose mounting flange for 12 mm diameter probes. It can be used to hold the HMP110 probe in a through-wall installation.

NOTE

The coaxial silicone plug that is delivered with the flange is not suitable for use with the probe cable of the HMT120.

Figure 8 Optional Probe Mounting Flange

0911-109

22 __________________________________________________________________ M211244EN-A


Probe Mounting Clamp

The optional mounting clamp (Vaisala order code: 226067) makes it easy to install the probe on the wall of the measurement environment. The probe can be detached for calibration simply by loosening the lower screw.

Installing the entire probe in the measurement environment prevents heat conduction to the sensor, and is the recommended installation method.

1001-138

Figure 9 Optional Probe Mounting Clamp

CAUTION

Attaching the probe mounting clamp to a conductive wall material should be avoided, since the potential galvanic connection to the power supplies and uncontrolled earth current loops could cause measurement errors or even damage to the HMT120 transmitter.

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Connections

C

A

RH

T T

ADJ

Figure 10 HMT120 Component Board


1 = Optional LCD display

1011-151

5 = Field wire terminals

1. Open the transmitter cover by pressing the releasing button at the bottom side of the transmitter.

2. Insert the signal wires through the selected cable gland/conduit fitting in the bottom of the transmitter or alternatively through the rubber grommet at the back side of the transmitter.

3.

Connect the wires as indicated in Figure 11 and in Table 3 on page

25. Suitable wire size is between 0.5mm

2

and 1.5 mm

2

.

24 __________________________________________________________________ M211244EN-A


NOTE

If an isolated output is required with current outputs, both channels require their own power supply. CH1 is always required to be powered because CH1 is the main output, and the transmitter will not operate if only CH2 is connected.

4. Close the cover by keeping it slightly tilted and first attaching it to the fixing snaps at the top of the enclosure base and then pushing the lower part of the cover firmly forward until it locks. The transmitter is ready for use.

Figure 11 Isolated Current-Loop Wiring

Table 3 Wiring Table

1011-152

1

2

3

4

5

Cable shield (optional)

CH1- (signal and power supply -)

CH1+ (signal and power supply +)

CH2- (signal and power supply -)

CH2+ (signal and power supply +)

The numbers 1 ... 5 in the first column of the wiring table refer to Figure

11 above.

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Chapter 4 ________________________________________________________________ Operation

CHAPTER 4

OPERATION

This chapter contains information that is needed to operate the HMT120.

Using the Service Port

HMT120 motherboard has an 8-pin RJ-45 connector for service use.

Service port uses RS-232 signaling levels. Vaisala offers an optional

USB cable (Vaisala order code 219685) for connecting the transmitter to your PC.

NOTE

The service port is intended for short-term use such as calibration. For permanent installation, use the analog output.

Connecting a PC to the service port may cause erroneous analog output because of a possible ground loop. Use the service port for service only and disconnect the PC after the service operation.

The cable can also provide operation power to the transmitter, so the wires at the screw terminals need not to be connected in order to operate the transmitter.

If you have not used the HMT120 USB cable before, install the driver

that came with the cable. Refer to section Installing the Driver for the

USB Cable below for detailed instructions.

Installing the Driver for the USB Cable

Before taking the USB 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 2000, Windows XP, Windows Server 2003, and Windows

Vista.

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1. Check that the USB 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.

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 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 different device, and reserve a new COM port. Remember to use the correct port in the settings of your terminal program.

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 from the Add or Remove Programs (Programs and Features in

Windows Vista) in the Windows Control Panel.

Terminal Application Settings

The default settings of the HMT120 serial interface are presented in

Table 4.

Table 4 Default Serial Interface Setting

Property Value

Baud rate 19200

Parity None

Data bits

Stop bits

Flow control

8

1

None

The steps below describe how to connect to the HMT120 using the

PuTTY terminal application for Windows (available for download at www.vaisala.com

) and a USB serial interface cable:

1. Connect the USB cable between your PC and the service port of the

HMT120.

2. Start the PuTTY application.

28 __________________________________________________________________ M211244EN-A

Chapter 4 ________________________________________________________________ Operation port is selected in the Serial line to connect to field.

Note: 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. using the serial line.

Note: 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.

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.

0807-004

Figure 12 PuTTY Terminal Application

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List of Serial Commands

All commands can be issued either in uppercase or lowercase.

The notation <cr> refers to pressing the carriage return (ENTER) key on your computer keyboard. Enter a <cr> to clear the command buffer before starting to enter commands.

Whenever you change any of the parameters and want to store the changes permanently, use the SAVE command.

Table 5 Serial Port Commands

Command Description

? Show transmitter information

ACAL

AERR

Calibrate analog outputs

Set/show analog output error levels

AOUT

ASEL

ATEST

CALCS

Show analog output status

Set/show analog output quantities and scaling

Test analog outputs

Set/show measured quantities

CRH

CRHCLR

CT

CTCLR

CTEXT

DSEL

ECHO

ENV

Calibrate probe RH

Restore probe RH factory calibration

Calibrate probe T

Restore probe T factory calibration

Set/show calibration info

Set/show displayed quantities

Set/show terminal echo mode

Set/show environmental parameters

ERRS

FORM

Display active errors

Set/show output formatting

FRESTORE Restore all transmitter settings to factory defaults

HELP List commands

INTV

R

Set/show the continuous output interval

Start continuous outputting

RESTORE

S

SAVE

SEND

SERI

SMODE

SYSTEM

UNIT

VERS

Restores the latest saved settings

Stop continuous outputting

Save changed settings to FLASH memory

Output the reading once

Set/show Service Port settings (Default: 19200 N 8 1)

Set the serial interface mode

Show transmitter information and build date

Set/show output unit

Show firmware version of the transmitter

30 __________________________________________________________________ M211244EN-A


Device Information and Status

Show Device Information

The ? command outputs a listing of device information.

?<cr>

Example:

>?

Device Name : HMT120

SW Name : HMT120/130

SW model : HMT120

SW version : 0.9.3.389

Serial number : "F2220101"

Unit : METRIC

Ch1 Status : ON

Ch2 Status : ON

Probe name : "HMP110"

Probe SW : "1.01.1"

Probe SW date : ""

Probe SN : "F0740011"

>

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USER'S GUIDE____________________________________________________________________

NOTE

Set/Show Available Quantities

The CALCS command shows the abbreviations of the quantities measured by HMT120. The command can also be used to select the desired quantities for measurement. Only after the quantities have been set with the CALCS command, can these quantities be selected for different outputs (see commands DSEL, ASEL, and FORM). The quantities in DSEL, ASEL, and FORM must match with CALCS.

CALCS [q1 q2]<cr> where

q1, q2

= Any two of the allowed quantity parameters, i.e. RH, T,

TD, TDF, A, X, H, TW, PWS, PW

Examples:

>calcs

RH Td

> calcs td t

>

Single-parameter transmitters HMT120H and HMT120T have only one quantity (T for HMT120T, and RH, TD, TDF, A, X, H, TW, PWS, PW for HMT120H.)

Set/Show Calibration Date

Use the CDATE command to show or set the calibration date field.

(Calibration refers to the calibration of the HMT120's analog outputs.)

CDATE [date]<cr> where

date

= Calibration date in format yyyy-mm-dd

Examples:

>cdate

Calibrated : "NOT SET"

>

>cdate 2009-06-22

Calibrated : "2009-06-22"

>

32 __________________________________________________________________ M211244EN-A


Set/Show Calibration Information

Use the CTEXT command to show or set the calibration info field.

(Calibration refers to the calibration of the HMT120's analog outputs.)

CTEXT [location]<cr> where

location

= Freely defined text string typically indicating the calibration location

Examples:

>ctext

Calib. info: "VAISALA HELSINKI"

>

>ctext "Calibration lab 2"

Calib. info: "Calibration lab 2"

>

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USER'S GUIDE____________________________________________________________________

Show Analog Output Status

The AOUT command shows the following information:

- Analog out mode is the output mode for the channel, for example

0 ... 10 V.

- Error level is the level that the analog output is set to in case of transmitter error.

- Status indicates the current status of the channel. The statuses are

- ON: Normal measurement operation.

- OFF: No quantity selected for the channel using the ASEL

command. See section Set/show Analog Output Quantity and

Scaling on page 42.

- ERROR: Transmitter error, channel set to error level.

- TEST: Analog channel being tested using the ATEST

command. See section Test Analog Outputs on page 44.

AOUT<cr>

Example:

>aout

*** ANALOG OUTPUT 1 ***

Ch1 Analog out mode : 4_20MA

Ch1 Notification : ON

Ch1 Error level : 3.6

Ch1 Status : ON

Ch1 Quantity : RH

RH lo : 0

RH hi : 100

RH : 23.32 %

Current : 7.73 mA

*** ANALOG OUTPUT 2 ***

Ch2 Analog out mode : 4_20MA

Ch2 Notification : ON


Ch2 Status : ON

Ch2 Quantity : T

T lo : -60

T hi : 100

T : 23.66 'C

Current : 12.37 mA

>

34 __________________________________________________________________ M211244EN-A


Show System Information

SYSTEM<cr>

Example:

>system

Device Name : HMT120

SW Name : HMT120/130

SW model : HMT120

SW version : 1.0.0.500

Serial number : A1234567

>

Show Firmware Version

VERS<cr>

Example:

>vers

HMT120 / 0.1.0.103

>

Serial Line Output Commands

Start Continuous Outputting

Use the R command to start the continuous outputting of measurement values as an ASCII text string to the serial line. The output always includes the readings of the currently selected analog output quantities.

R [X]<cr>

Example:

>r

RH= 25.10% T= 24.77'C

RH= 25.12% T= 24.96'C

…

Outputting the results continues in intervals issued with the command

INTV. You can stop the output by entering the S command.

Output data formatting can be defined with FORM command. With X parameter the transmitter will output RH + T value in predefined format regardless of what quantities are selected.

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USER'S GUIDE____________________________________________________________________

Stop Continuous Outputting

Use the S command to stop the continuous measurement output:

S<cr>

Set/show Output Interval

Use the INTV command to show or set the output interval of the serial line measurement messages (applies when R command or RUN mode is used). The shortest output interval is one second. This command has no effect on the operation of the analog outputs.

INTV [n xxx]<cr> where

n xxx

Examples:

= Time interval in range 1 ... 255

= Time unit = "S", "MIN", or "H"

>intv

Value : 1

Unit : S

>

>intv 3 min

Value : 3

Unit : MIN

>

Output a Reading Once

Use the SEND command to output a single measurement reading from the transmitter.

SEND [X]<cr>

Example:

>send

RH= 25.12 % T= 24.91 'C

>

With X parameter the transmitter will output RH + T value in predefined format regardless of what quantities are selected.

36 __________________________________________________________________ M211244EN-A


Calibration Commands

Serial commands that are related to calibration are described below. For

the actual calibration procedures, see section Calibration and

Adjustment on page 54.

Calibrate Humidity Measurement

Use the CRH command to perform a one-point or two-point humidity

(RH) calibration.

CRH<cr>

When performing a one-point calibration, you need to place the probe 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 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 1: One-point calibration

>crh

RH: 11.29915720 Ref1 ? 11.3

Press ENTER to continue or ESC to exit

OK

>

Example 2: Two-point calibration

>crh

RH: 11.29915720 Ref1 ? 11.3


RH: 75.04306440 Ref2 ? 75

OK

>

Example 3: No calibration, only updating the value

>crh

RH: 20.28000200 Ref1 ?

RH: 20.14000000 Ref1 ?

Calibration terminated with ESC

>

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Restore Probe RH Factory Calibration

Use the CRHCLR to restore the probe RH factory calibration.

CRHCLR<cr>

Example:

>crhclr

OK

>

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 probe 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. To update the value, press ENTER without inputting a value.

For two-point calibration, the second reference point must be at least

20 ºC warmer than the first. The measurement reading for the second point will appear when this requirement is met.

Example 1: One-point calibration

>ct

T 21.9827 Ref1 ? 22


OK

>

Example 2: Two-point calibration

>ct

T 22.0007 Ref1 ? 22


T 44.9847 Ref2 ? 45

OK

>

Example 3: No calibration, only updating the value

>ct

T 22.0007 Ref1 ?

T 22.0145 Ref1 ?

Calibration terminated with ESC

>

38 __________________________________________________________________ M211244EN-A


Restore Probe T Factory Calibration

Use the CTCLR to restore the probe T factory calibration.

CTCLR<cr>

Example:

>ctclr

OK

>

NOTE

Calibrate Analog Output

Use the ACAL command to calibrate the analog current loop outputs.

ACAL<cr>

After you give this command, the CH1 analog output of the transmitter is set to the low limit (4mA). Measure the output and enter the measured value. After entering the low limit, you must measure and enter the high limit (20mA) also. The same procedure is then repeated with CH2.

Calculated coefficients are printed after the measured values are given.

Example:

>acal

Ch1 I1 (mA) ? 5.60

Ch1 I2 (mA) ? 18.40

-1.40562890E+03 a0

1.41171900E+03 a1

OK

Ch2 I1 (mA) ? 5.60

Ch2 I2 (mA) ? 18.40

-1.40562890E+03 a0

1.41171900E+03 a1

OK

>

Question mark is displayed after certain stabilization time has expired.

Values should be entered only after question mark is displayed. Values entered before question mark will be discarded.

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USER'S GUIDE____________________________________________________________________

Configuring Serial Line Operation

Set/Show Serial Line Settings

Use the SERI command to show or set the serial line settings. Use the

SAVE command after changing the settings to store them. The new settings will be taken into use when the transmitter is reset or powered up.

SERI [b p d s]<cr> where

b

= baud rate (9600, 19200, 38400, 76800, 115200)

p

= parity (n = none, e = even, o = odd)

d

= data bits (7 or 8)

s

= stop bits (1 or 2)

Examples:

>seri

Baud P D S : 19200 N 8 1

>

>seri 9600 e 7 1

Baud rate : 9600

Parity : E

Data bits : 7

Stop bits : 1

>save

Saving settings...done

>

Set/Show Terminal Echo

To show or set the terminal echo status, use the ECHO command.

ECHO [ON/OFF]<cr>

Examples:

>echo

COM1 Echo : OFF

>

>echo on

COM1 Echo : ON

>

40 __________________________________________________________________ M211244EN-A


Set/Show Serial Interface Mode

Use the SMODE command to show or set the serial interface mode. Note that a separate SAVE command is not needed to store the new serial interface mode setting.

SMODE [STOP/RUN]<cr>

In STOP mode: outputting only when command is issued, any command can be used.

In RUN mode: outputting automatically, only command S can be used.

Example:

>smode stop

Output mode : STOP

>

Configuring Measurement Parameters

Set/Show Environmental Parameters

Use the ENV command to show or set the environmental compensation values. In HMT120, the humidity measurement can be compensated for ambient pressure. The value set using ENV command is a permanent value which will survive a restart.

ENV [x.xxxx]<cr> where

x.xxxx

= Absolute pressure in the measuring environment.

The default is 1.013. The pressure unit is bar.

Example:

>env

Pressure (bar) : 1.013

>

>env 0.980

Pressure (bar) : 0.98

>save


>

NOTE

You can use the Vaisala Humidity Calculator to simulate the effect of pressure change to dewpoint. The Humidity Calculator can be found at: www.vaisala.com/humiditycalculator

VAISALA _______________________________________________________________________ 41

USER'S GUIDE____________________________________________________________________

Configuring Analog Output

Set/show Analog Output Error Levels

Use the AERR command to show or set the analog output error levels.

AERR [level1 level2]<cr> where

level1 level2 = Error levels for analog output channel

Examples:

>aerr



>

>aerr 3.85 3.86



>

Set/show Analog Output Quantity and

Scaling

After you have defined the quantities with the CALCS command, use the

ASEL command to show or set the quantity output by the analog channels, and the scaling that is used. If you do not enter scaling limits, default values are used. Valid quantities are: RH, T, TD, TDF, A, X, H,

TW, PWS, PW and NONE. NONE parameter disables analog output and output is forced to error level.

ASEL [q1 q2] [lo1 hi1 lo2 hi2]<cr> where

q1 q2

= Analog output channel quantities

lo1 lo2

= Low limits of scaling

hi1 hi2

= High limits of scaling

42 __________________________________________________________________ M211244EN-A


Syntax for single-parameter transmitters:

ASEL [q] [lo hi]<cr> where

q lo hi

Examples:

= Analog output channel quantity

= Low limit of scaling

= High limit of scaling

>asel

Ch1 Quantity : RH

RH lo : 0

RH hi : 100

Ch2 Quantity : T

T lo : -60

T hi : 100

>

>asel rh td

Ch1 Quantity : RH

RH lo : 0

RH hi : 100

Ch2 Quantity : TD

Td lo : -40

Td hi : 60

>

>asel t td 0 60 -20 60

Ch1 Quantity : T

T lo : 0

T hi : 60

Ch2 Quantity : TD

Td lo : -20

Td hi : 60

>

>asel rh none

Ch1 Quantity : RH

RH lo : 0

RH hi : 100

Ch2 Quantity : NONE

>

>asel none none

Ch1 Quantity : NONE

Ch2 Quantity : NONE

>

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Test Analog Outputs

Use the ATEST command to test the analog outputs. The ATEST command will force the output to the given value, which can then be measured with a calibrated multimeter.

ATEST command affects only the analog outputs and hence it does not disable measurement functions. ATEST without parameters will exit the test mode and let the measurement continue. It will also indicate the the current analog output levels in normal measurement state.

ATEST [val1 val2]<cr> where

val1 val2

= Analog channel output value (mA)

Examples:

>atest

CH1: 3.800000

CH2: 3.800000

>

>atest 3.9 3.9

CH1: 3.900000

CH2: 3.900000

>

44 __________________________________________________________________ M211244EN-A


Other Commands

Set/show Displayed Quantities


DSEL command to show or set the displayed quantities. Number of parameters determine the display mode (ie. one or two rows). If one quantity is given, display will switch to one row mode. If two quantities are given, two-row mode is used. Valid quantities are: RH, T, TD, TDF,

A, X, H, TW, PWS, and PW.

DSEL [q1 q2]<cr> where

Q1 q2

= Quantities to be shown on transmitter display

Syntax for single-parameter transmitters:

DSEL [q]<cr> where

Q

= Quantity to be shown on transmitter display

Examples:

>dsel

1. quantity : RH

2. quantity : T

>

>dsel rh t

1. quantity : RH

2. quantity : T

>

>dsel t

1. quantity : T

>

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USER'S GUIDE____________________________________________________________________

Set/show Output Formatting


FORM command to set the output format for SEND and R commands.

FORM<format> where

format = A formatting string, which can consist of following fields:

“” String x.y Value length modifier. x is numbers before dot

Ux

Q and y is numbers after dot.

Unit field length. U…U format is also supported.

Quantity name (e.g. rh, t, td etc.)

#t or \t Tabulator

#r or \r Carriage return

#n or \n Line feed (new line)

Note 1. Quantity must be after x.y and Ux modifiers.

Note 2. There must be a space between parameters, #r#n or \r\n is not supported.

Note 3. Max. string length is 80 characters.

Note 4. If Ux parameter is not used, unit is not displayed.

Examples:

>form "RH= " 3.2 U2 rh #r #n

>send

RH= 32.16 %

>

>form "t=" 4.1 U3 t \t "rh=" 3.2 U2 rh \r \n

>send t= 22.5 'C rh= 29.12 %

>

>form "t=" 4.1 U3 t \t "rh=" rh \r \n

>send t= 22.3 'C rh= 29.5 %

>

>form 3.2 UUU "RH=" rh \t "T=" t \r \n

>send

RH= 27.99 % T= 23.34 'C

>

>form 3.3 rh " " t \r \n

>send

26.740 23.660

>

>form "->" "RH=" 3.2 U2 rh " " "T=" 3.1 U3 t #r #n

>send

->RH= 27.79 % T= 23.4 'C

>

46 __________________________________________________________________ M211244EN-A


Display Command List

Use the HELP command to display a list of available commands.

HELP<cr>

NOTE

Display Active Errors

Use the ERRS command to display the currently active error codes. For

troubleshooting active errors, see Table 7 on page 71.

ERRS<cr>

Example (no active errors):

>errs

No errors.

>

Save Changed Settings

Use the SAVE command to save changed settings to the transmitter

FLASH memory. Most settings have to be saved or the changes are lost at the next reset or power down.

The SMODE command saves the new serial mode immediately; a separate SAVE command is not needed.

The probe calibration commands (CRH, CT, CRHCLR, CTCLR) store the parameters into the probe's memory automatically without a separate

SAVE command.

SAVE<cr>

Example:

>save


>

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Restore Saved Settings

Use the RESTORE command to restore saved settings from transmitter

FLASH memory to RAM. All unsaved changes will be lost.

RESTORE<cr>

Example:

>restore

Restoring default settings...done

>

Reset Transmitter

Use the RESET command to reset the transmitter. Upon reset or powerup, the transmitter enters the serial mode that has been set with the

SMODE command.

After reset the configuration is loaded from FLASH memory. That configuration can be altered with SAVE-command.

RESET<cr>

Example (transmitter set to serial mode STOP, will output transmitter software version at reset):

>reset

HMT120 / 0.1.0.001

Type "help" for command list

>

Restore Factory Settings

Use the FRESTORE command to restore the factory settings to the transmitter. All user settings, including the user-performed calibration corrections, will be lost. The transmitter will revert back to the factory calibrated settings. Note that this only returns the factory settings of the

transmitter and not of the interchangeable probe (see section Restore

Probe RH Factory Calibration on page 38 and section Restore Probe T

Factory Calibration on page 39).

FRESTORE<cr>

Example:

>frestore

Restoring factory defaults...done

>

48 __________________________________________________________________ M211244EN-A


Set/show Output Unit

Use the UNIT command for output unit selection (metric or non-metric).

UNIT [METRIC/NON_METRIC]<cr>

Example:

>unit

Unit : METRIC

>

>unit non_metric

Unit : NON_METRIC

>

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50 __________________________________________________________________ M211244EN-A

Chapter 5 ______________________________________________________________ Maintenance

CHAPTER 5

MAINTENANCE

This chapter provides information that is needed in basic maintenance of the product.

Replacing the HUMICAP

®

Sensor

Fixed and Remote Probe Models

1. Remove the filter (plastic grid or sintered stainless steel).

2. Remove the damaged sensor and insert a new one.

4. Replace a dirty filter to ensure a maximum lifetime and a fast response for the sensor. Do not attempt to clean the filter.

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Removing and Fastening the Probe

Fixed Probe Model

Remove and replace the probe as follows:

1. Loosen the metal locking bushing by carefully turning it counter clockwise.

2. Remove the probe from the transmitter by pulling it gently downwards.

3. Attach the new probe to the four pin M8 panel connector at the transmitter (only one position possible).

4. Tighten the locking bushing to the M8 panel connector by turning it clockwise

1011-153

Figure 13 Removing the Humidity Probe (Fixed Probe Model)


2 = Holder bushing (attached permanently to the probe)

52 __________________________________________________________________ M211244EN-A


Remote Probe Model

1. Unscrew the small sleeve that secures the probe in place at the end of the probe cable and pull out the probe.

2. Replace the probe and screw the small sleeve back on, securing the probe tightly in place.

1011-154

Figure 14 Removing the Humidity Probe (Remote Probe Model)


2 = Sleeve securing the probe to the cable

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USER'S GUIDE____________________________________________________________________

Calibration and Adjustment

Calibrate and adjust the HMT120 using the push-buttons on the motherboard, serial line commands, or with portable humidity meters

HM70 or HMI41.

A calibrator kit is needed for calibration against saturated salt solutions.

The HMK15 Humidity Calibrator and pre-measured certified salts are available from Vaisala. For further information, please contact your

Vaisala representative.

Vaisala Service Centers also offer accredited calibrations for humidity

and temperature. See contact information on page 73.

It is also possible to remove the HMP110 probe and replace it with a new one. The old probe can be adjusted using another HMT120 transmitter body, if you have one available.

NOTE

RH Field Calibration and Adjustment, as instructed in the following pages, is restricted to a certain adjustment range to minimize the effects of special circumstances, such as chemical contamination. In case the probe is outside its adjustment/trim range due to, for example, chemical exposure, the calibration cannot be completed. In this case, it is recommended that you change the probe or contact Vaisala Services.

HMT120 Push-Button Calibration

1011-155

Figure 15 Adjustment Buttons

Calibration and adjustment of the HMT120 can be done by using the adjustment buttons found at the transmitter. The two-point humidity adjustment is carried out by using two relative humidity references: for example saturated salt points 11 %RH (LiCl) and 75 %RH (NaCl). The

54 __________________________________________________________________ M211244EN-A

Chapter 5 ______________________________________________________________ Maintenance difference between the two humidity reference points must be at least

30 %RH. The difference between the two temperature reference points must be at least 30 °C.

NOTE

In push-button calibration, the transmitter outputs are by default relative humidity in the range 0…100% RH in CH1 and temperature in the range

-40 … +60 °C in CH2 regardless what the actual transmitter settings are.

Outputs mean in this case both the display and analog current outputs.

NOTE

NOTE

Humidity and Temperature Adjustment

To make a humidity or temperature adjustment (the same instructions apply to both one-point and two-point calibration):

1. Open the transmitter cover and you can see three buttons marked ADJ, + and -. There are also two indicator LEDs, one green and one red on the HMT120 motherboard.

LED begins to blink slowly (800ms cycle time).

3. HMT120 transmitter is now in RH calibration state. Analog output and optional display will still follow the actual measured RH value.

If you do not wish to perform the RH adjustment at this time, press ADJ button one more time. The green indicator LED turns off and the red indicator LED begins to blink slowly (800ms cycle time) to indicate T calibration state. Now you can continue following the instructions from step 7 onward.

4. Remove the filter and insert the probe into a measurement hole of the dry end reference chamber (for example, LiCl: 11 %RH) to do the low humidity offset adjustment.

Do not touch the adjustment buttons before the conditions have stabilized. This takes approximately 30 minutes.

- or + button at least once, make sure that the I out current is correct, adjust using the - and + buttons if needed, and press the ADJ button again. The green indicator LED begins to blink faster (400ms cycle time).

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NOTE

If you do not wish to perform the two-point RH adjustment at this time, press the ADJ button one more time. The green indicator LED turns off and the red indicator LED begins to blink slowly (800ms cycle time) to indicate T calibration state. Now you can continue following the instructions from step 7 onwards.

If one-point calibration is done at more than 50 %RH, a gain adjustment is done instead of an offset adjustment.

NOTE

6. Insert the probe into the high end reference chamber (for example,

NaCl: 75 %RH chamber in the humidity calibrator HMK15) and do the high humidity gain adjustment by using the - and + buttons to make sure the I out

current is correct (you have to press either - or + at least once even if the value is correct). To finish the RH calibration, press the ADJ button. The green LED is now turned off and the red indicator LED begins to blink slowly (800ms cycle time).

7. HMT120 transmitter is now in T calibration state. Analog output and optional display will still follow the actual measured T value.

If you do not wish to perform the T adjustment at this time, press ADJ button one more time. The red indicator LED is turned off and the transmitter returns to normal mode. The calibration procedure is now finished.

NOTE

8. Insert the probe into a known reference temperature (if HMK15

Humidity Calibrator is not used) and let the temperature reading stabilize.

Do not touch the adjustment buttons before the conditions have stabilized.

NOTE

by making sure the I out

current is correct (you have to press either - or + at least once even if the value is correct) and press the ADJ button. The red indicator LED begins to blink faster (400ms cycle time).

If you do not wish to perform the two-point T adjustment at this time, press the ADJ button one more time. The red indicator LED is turned off and the transmitter returns to normal mode. The calibration procedure is now finished.

10. Insert the probe into another reference temperature.

56 __________________________________________________________________ M211244EN-A


NOTE

Do not touch the adjustment buttons before the conditions have stabilized.

NOTE

NOTE

by making sure the I out

current is correct (you have to press either - or + at least once even if the value is correct). off and the transmitter returns to normal mode. The calibration procedure is now finished.

In case of calibration error, both LEDs blink alternately at a very fast rate (cycle time 200ms) for a period of 2s after which the transmitter returns to normal mode.

In case of using a HMT120 transmitter with display option, the following texts are shown at the display during calibration:

"Probe cal: RH 1" corresponding the green LED blinking slowly

"Probe cal: RH 2" corresponding the green LED blinking fast

"Probe cal: T 1" corresponding the red LED blinking slowly

"Probe cal: T 2" corresponding the red LED blinking fast

"Probe cal: Error" corresponding both LEDs blinking alternately at very fast rate

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Adjustment with HM70

You can check and adjust the HMT120 relative humidity measurement with the HM70 Hand-Held Humidity and Temperature meter. A HM70connection cable is needed. Vaisala order code: 211339.

There are four types of adjustments available: field checking and adjustment using a calibrated reference probe, one-point adjustment using a calibrator, two-point adjustment using a calibrator, and LiCl-

NaCl adjustment.

Follow the first seven steps and continue according to the chosen adjustment method.

NOTE

0505-351

Figure 16 Location of the MI70 Probe and Cable Connector

Ports

1. Connect the 211339 HM70-connection cable to the

SERVICE PORT

connector on the HMT120 motherboard (see Figure 10 on page

24).

2. Connect the other end of the connection cable to either of the

HM70's connector ports located on the bottom of the indicator (see

Figure 16 above).

3. Turn on both devices (or just HM70, in case that HMT120 is on continuously).

4. Check that the transmitter reading is shown on the indicator. The reading of the transmitter is shown on the top or middle row of the display, depending on which connector port the connection cable is connected to. the button on the HMT120 motherboard to open the adjustment mode. Both LEDs on HMT120 motherboard remain in

OFF state and text "Starting adjustment mode for HMP110" is shown at the MI70 display.

In case of using a HMT120 transmitter with display option, text "MI70

adjustment mode" is shown on the upper row of HMT120 display.

58 __________________________________________________________________ M211244EN-A


NOTE

From this point onward, the local adjustment buttons at HMT120 are disabled and adjustment is carried out using the MI70 indicator.

HMT120 display and analog outputs will always follow the actual measured RH/T value when in MI70 adjustment mode. When operating the MI70, do not press the buttons too quickly or the calibration may fail. Wait for one second between each press.

7. Check the environment settings if needed. Otherwise, press

NO

.

Select

RH

or

T adjustment

. Continue according to the directions of the desired adjustment method.

Field Checking and Adjustment Using a Calibrated

Reference Probe

Follow steps 1 to 7 on page 58 and continue as follows:

8. Check that the probes are located in equal conditions and wait until the readings have stabilized. This may take 30 minutes or more. If you are close to the probes, do not breath in their direction.

9. Press

ADJUST

to continue adjusting.

10. Choose

To same as RH

I/II

from the MI70 adjustment menu, press

SELECT

(MI70 automatically recognizes which port the HMP70 series probe is connected to).

11. Confirm the adjustment by pressing

YES

.

12. The adjustment is done. Press

BACK

and

EXIT

to return to the basic display.

13. Turn off the MI70 and detach the connection cable.

One-Point Adjustment Using a Calibrator

When adjusting the transmitter in only one reference condition, please take care that the reference condition represents the measuring environment. MI70 indicator is used now only as a terminal for visualizing and setting the transmitter's RH reading.


8. Remove the filter from the transmitter's probe and insert the probe head into the reference condition.

9. Press

ADJUST


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10. Choose

1-point adjustment

from the MI70 adjustment menu and press

SELECT

.

0505-185

Figure 17 Example of the MI70 Adjustment Menu

11. Press

READY

when the reading has stabilized in the reference condition. This may take 30 minutes or more. You can follow the stabilization from the

GRAPH

display.

0505-186

Figure 18 Example of the MI70 Adjustment Mode Graph

Display

12. Enter the correct reference value with the arrow buttons. Press

OK

.


YES

.


BACK

and

EXIT



Two-Point Adjustment Using a Calibrator

Note that the difference between the two reference humidities must be at least 50 %. MI70 indicator is used now only as a terminal for visualizing and setting the transmitter's RH reading.


8. Remove the filter from the transmitter's probe and insert the probe head into the lower humidity reference condition.

9. Press

ADJUST


10. Choose

2-point adjustment


SELECT

.

60 __________________________________________________________________ M211244EN-A


11. Press

READY

when the reading has stabilized in the first reference condition (may take 30 minutes or more). You can follow the stabilization from the

GRAPH

display.

12. Enter the correct reference value in the first condition with the arrow buttons. Press

OK

.

13. Remove the probe from the first reference condition and insert the probe head into the higher humidity reference condition.

14. Press

READY

when the reading has stabilized in the second reference condition (may take 30 minutes or more). You can follow the stabilization from the

GRAPH

display.

15. Enter the correct reference value in the second condition with the arrow buttons. Press

OK

.


YES

(by pressing

NO

you return to adjustment mode display and no changes are made). If the difference between the two reference conditions is less than

50 %RH, adjustment cannot be done.


BACK

and

EXIT



LiCl-NaCl Adjustment

This adjustment is done using relative humidity references 11.3 %RH

(LiCl) and 75.5 %RH (NaCl).


8. Remove the filter from the transmitter's probe and insert the probe head into the LiCl salt chamber.

9. Press

ADJUST


10. Choose

LiCl-NaCl autom.


SELECT

. Press

OK

to accept the note telling about references.

11. Press

READY

when the reading has stabilized in the LiCl salt chamber (may take 30 minutes or more). You can follow the stabilization from the

GRAPH

display.

12. Remove the probe from the LiCl salt chamber and insert the probe head into the NaCl salt chamber.

13. Press

READY

when the reading has stabilized in the NaCl salt chamber (may take 30 minutes or more). You can follow the stabilization from the

GRAPH

display.

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YES

(by pressing

NO

you return to adjustment mode display and no changes are made).


BACK

and

EXIT



NOTE

Temperature Field Check and Adjustment by Using a

Calibrated Reference Probe


8. Check that the probes are located in equal conditions and wait until the readings are stabilized (can take 30 minutes or more). If you are close to the probes, do not breathe in their direction.

9. Press

ADJUST


10. Press

To same as T

II/I

, press

SELECT

. (MI70 always recognizes the port to which the HMP70 series probe is connected).

11. Confirm by pressing

YES

.

If the temperature difference between the reference probe and HMT120 is too large, the adjustment cannot be done (HM70 will notify you of this). The available reserve for T adjustment of HMT120 depends on the initial temperature calibration of the unit.

12. Adjustment is done. Press

BACK

and

EXIT


13. Switch off the MI70 and detach the calibration cable from MI70 and from the transmitter.

62 __________________________________________________________________ M211244EN-A


Adjustment with HMI41

You can check and adjust the HMT120 relative humidity measurement with the HMI41 indicator and HMP41/45/46 probes. A HMI41connection cable is needed. Vaisala order code: 25917ZZ.

There are three adjustment modes available: offset (dry point), gain (wet point), and two-point adjustment. All of these can be performed using the

HMI41 either as a reference meter (for example when the transmitter is mounted in an air-conditioning channel) or only as a terminal for visualizing and setting the transmitter's RH reading.

Offset and gain adjustments are performed the same way and differ only in internal calculations. Select offset adjustment when the reference humidity is < 65 %RH and gain adjustment when the reference humidity is ≥ 65 %RH. Two-point adjustment is more accurate, and includes both offset and gain corrections. For performing two-point adjustment, you need two separate measurement points with a difference of at least 50

%RH between them.

Follow the general directions of connecting the HMI41 to the HMT120 and selecting the HMI41 calibrator function and then continue according to the chosen adjustment method.

1

3

2

0505-187

Figure 19 Location of the HMI41 Calibration Connector


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Connections and Selecting the Calibrator Function

1. To select the calibrator function from the HMI41, press the

ON/OFF

button until you can see some text on the display. Then release the

ON/OFF

button and within 1 ... 2 seconds, press both

ENTER

and

MODE

buttons until the following display appears:

2. After a few seconds, the display changes to show the following:

°C set

If the basic settings (display units, automatic power off function, display quantities, and pressure) have to be changed, please refer to the HMI41 Operating Manual. Otherwise, press

ENTER

repeatedly until the following display appears: set

To calibrate the HMT120, select number 3 with buttons ▲ (number up) and ▼ (number down) and then press

ENTER

.

3. Next the baud rate appears on the display. Use the baud rate 19200

(= 19.2 on the HMI41 display) with the HMT120 series. If the baud rate on the HMI41 display is not correct, change it with buttons ▲ and ▼. When the baud rate is correct, press

ENTER

, and the serial communications settings display appears. The correct settings for HMT120 series are: N, 8, 1. If needed, change the settings with buttons ▲ and ▼ until they are correct, press

ENTER

, and then

ON/OFF

.

These setting are stored in the HMI41 memory; when the HMI41 is turned on again, it will automatically wake up as a calibrator for digital transmitters with these serial line settings. After making these settings, continue with the adjustment and follow the directions of the chosen adjustment method.

64 __________________________________________________________________ M211244EN-A


Offset and Gain Adjustments

Offset and gain adjustments are performed in the same way (they differ only in internal calculations), so this section is valid for both methods.

4. Connect the 25917ZZ HMI41-connection cable to the

SERVICE PORT

connector on the HMT120 motherboard (see Figure 10 on page

24).

5. Connect the other end of the connection cable to the

EXT

connector

located on the bottom of the HMI41 indicator (see Figure 19 on page 63).

6. Turn on both devices. Wait until the following display appears:

RH

NOTE

7. Select the appropriate adjustment mode with the ▲ and ▼ buttons.

Select offset adjustment if the humidity is < 65 %RH and gain adjustment if the humidity is ≥ 65 %RH:

RH

RH or

Press

ENTER

to confirm the selection. A display similar to the following appears:

RH %

In case of using a HMT120 transmitter with display option, the text

"HMI41 adjustment mode" is shown at the upper row of HMT120 display.

The next sections describe how to perform offset and gain adjustments in two different ways.

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HMI41 as a Reference Meter

The HMI41 humidity probe is used to show the correct humidity value

(be sure that the reference probe has previously been adjusted). Connect the cable and select the appropriate adjustment method as previously explained, and continue according to the following instructions.

8. A display similar to the one below should be visible:

RH %

Numbers on the first line indicate the transmitter reading, and the numbers on the second line indicate the reference probe reading.

9. Let the readings stabilize (may take 30 minutes or more). If you prefer, you can change the display to show the difference in the readings. Press

HOLD

and a display similar to the following appears:

RH %

The numbers on the first line indicate how much the transmitter reading differs from that of the HMI41 reference probe. The numbers on the second line indicate the reference probe reading.

You can return to the previous display by pressing

HOLD

again.

10. When the readings have stabilized, press

ENTER

to conclude the adjustment. When

ENTER

is pressed, the transmitter reading is corrected to the reference probe reading. If the adjustment has been succesful, the following display appears:

RH

11. The data is now stored in the transmitter memory. If the adjustment has not been succesful, the following display appears:

RH

In this case, perform the adjustment again. Whether the adjustment was succesful or not, the HMI41 always returns to display the selected adjustment mode.

12. After succesfully completing the adjustment, turn off the HMI41 and disconnect the cable.

66 __________________________________________________________________ M211244EN-A


HMI41 as a Terminal

The HMI41 can also be used for visualizing and setting the transmitter's

RH reading manually.

8. A display similar to the one below should be visible:

RH %

The numbers on the first line indicate the transmitter reading, and the numbers on the second line indicate the HMI41 probe reading.

9. Let the readings stabilize and press

MODE

. The following display appears:

RH % set

The HMI41 now works only as a terminal for setting the humidity reading. The numbers on the first line are blinking, and the numbers on the second line indicate the transmitter reading.

10. You can now set the blinking reading to the correct value (for example, the equilibrium RH of a salt solution) with the buttons

▲ and ▼. Press

ENTER

to conclude the adjustment. If the adjustment has been succesful, the following display appears:

RH

11. The data is now stored in the transmitter memory. If the adjustment has not been succesful, the following display appears:

RH

In this case, perform the adjustment again. Whether the adjustment was succesful or not, the HMI41 always returns to display the selected adjustment mode.

12. After succesfully completing the adjustment, turn off the HMI41 and disconnect the cable.

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Troubleshooting

Table 6 presents a summary of the error messages that may appear during

adjustment with the HMI41.

Table 6 Common Problems During Adjustment and Their

Remedies

Error Message

RH

Probable Cause

This message may appear, for example, if the difference between the reference humidities is too small (< 50 %RH).

This message may appear during adjustment when the

HMI41 is trying to contact the transmitter.

The connection cable is not properly connected or the serial line settings of the HMI41 and the transmitter do not correspond.

Remedy

Perform the adjustment again.

Wait.

Check the connection of the calibration cable.

Check that the serial line settings in the HMI41 memory correspond to those of the transmitter.

68 __________________________________________________________________ M211244EN-A


Analog Output Tests

HMT120 has a built-in software function for testing the analog outputs.

To test the outputs, do the following:

1. Make sure the transmitter is not in adjustment mode.

2.

Press the + adjustment button (see Figure 15 on page 54).

This sets the output current level to the high point of the analog output range (20mA nominal). The output stays at this level for about 30 seconds after the + adjustment button has been pressed.

3.

Press the - adjustment button (see Figure 15 on page 54).

This sets the output current level to the low point of the analog output range (4mA nominal). The output stays at this level for about 30 seconds after the - adjustment button has been pressed.

HMT120 analog output current can be measured without removing the wires from the screw-terminals by using a low-impedance multimeter between the associated +-terminal and test point (CH1 or CH2) on the

component board, see figure 1011-157

Figure 20 below for reference.

NOTE

1011-157

Figure 20 HMT120 Output Current Measurement

In case of using a HMT120 transmitter with display option, the following texts are shown at the display during analog output test:

"Analog output test high" corresponding to 20mA current output

"Analog output test low" corresponding to 4mA current output

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70 __________________________________________________________________ M211244EN-A

Chapter 6 ___________________________________________________________ Troubleshooting

CHAPTER 6

TROUBLESHOOTING

This chapter describes error messages and analog output error behavior, introduces some common problems, their probable causes and remedies and provides contact information for technical support.

Error Codes

HMT120 software includes number of different self diagnostics, such as flash and program memory checksum, probe communication status, probe checksum, operation voltage check, oscillator fault check etc.

At startup software checks factory/user settings checksum, program memory checksum and oscillator fault status. Other checks are made during runtime. Available error codes are shown in the table below.

Table 7 Error Codes and Texts

Code Description

9

10

11

12

13

14

5

6

7

8

1

2

3

4

Probe T measurement error

Probe RH measurement error

Probe communication error

Probe checksum error

Probe message form error

Program's flash checksum error

Current settings checksum error (RAM)

Factory flash not initialised

User flash not initialised

Voltage is too low to operate correctly

Measurements not available

Oscillator fault bit active

Analog output quantity invalid

Display quantity invalid

Probe T meas

Probe RA meas

Probe communication

Probe checksum

Probe message form

Program code checksum

Settings checksum

Factory defaults empty

User defaults empty

Voltage too low

Measurements not available

HW fault 1

Analog output quantity invalid

Display quantity invalid

Error text is shown by using the ERRS command via the serial interface.

In case of using a HMT120 transmitter with display option the error code is shown at the display in format "ERR:Code-1[.Code-2][.Code-n]".

Multiple errors are separated with a dot between the error codes.

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Solving Typical Problems

You can check the error message via the serial interface by using the

ERRS command; see section Error Codes on page 71. In case of

constant error, please contact Vaisala Technical Support.

Table 8 Troubleshooting Table

Problem or Message

Measurement not working, any of the following errors is active:

- Probe RH measurement error

- Probe T measurement error

Transmitter cannot communicate with the probe, any of the following errors is active:

- Probe communication error

- Probe checksum error

- Probe message form error

- Measurements not available

Serial line command not working, outputs "Unknown command."

Cannot connect to serial line, current serial settings of the module are unknown.

Likely Causes and Solutions

- Sensor(s) damaged or missing. Open the probe filter and check.

- Calibration is not done. Calibrate the probe.

- Check the supply voltage of the transmitter.

- Check the attachment of the probe to the transmitter.

- In case of remote probe, check also the interconnection cables.

- Replace the probe if necessary.

Any of the following errors is active:

- Current settings checksum error

- Default settings checksum error

- Mistyped or unknown command, check the command syntax and parameters.

Perform the following steps to connect:

1. Set your terminal settings to 19200 8 N 1

(the default settings of the transmitter).

2. Connect to the service port of the transmitter.

2. Power up the transmitter, and type "Z" on the serial line at least five times.

4. The transmitter will come online with the default settings.

5. Use the SERI command to set the desired serial settings, and use the SAVE command to save them.

Internal error. Perform the following steps:

1. Reset or power cycle the module. Check if the error disappears.

2. Return the module to factory settings using the FRESTORE command. Check again.

3. If the error is still active, contact a Vaisala service center.

Faulty transmitter, contact a Vaisala service center.


- Program checksum error

- Factory flash defaults checksum error

- Factory flash not initialized

- Oscillator fault bit active


- Analog output quantity invalid

- Display quantity invalid

In case of "Analog output quantity invalid" error select the correct output quantities (set with the CALCS command) with ASEL command and in case of "Display quantity invalid" error select the correct display quantities with DSEL command.

72 __________________________________________________________________ M211244EN-A

Chapter 6 ___________________________________________________________ Troubleshooting

Analog Output Error Notification

If the transmitter is unable to operate due to an error, the analog outputs will be set to an error level.

Default output current in error state is 3.6mA. Error current value can be changed via the serial interface by using the AERR command; see

section Set/show Analog Output Error Levels on page 42.

Technical Support

For technical questions, contact the Vaisala technical support via e-mail at [email protected]

.

For contact information of Vaisala Service Centers, see www.vaisala.com/services/servicecenters.html

.

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74 __________________________________________________________________ M211244EN-A

Chapter 7 ____________________________________________________________ Technical Data

CHAPTER 7

TECHNICAL DATA

This chapter provides the technical data of the product.

Specifications

Table 9 Relative Humidity Measurement Specifications

Property

Measurement range

Accuracy (including non-linearity, hysteresis, and repeatability): at 0 ... +40 °C (+32 ... +104 °F)

Description / Value

0 ... 100 %RH at -40 ... 0 °C and +40 ... +80 °C

(-40 ... +32 °F and +104...+176 °F)

±1.7 %RH (0 ... 90 %RH)

±2.5 %RH (90 ... 100 %RH)

±3.0 %RH (0 ... 90 %RH)

±4.0 %RH (90 ... 100 %RH)

Factory calibration uncertainty at

+20 °C (+68 °F)

Humidity sensor

Table 10

±1.5 %RH

HUMICAP

®

180R

Temperature Measurement Specifications

Property Description / Value

Measurement range -40 ... +80 °C (-40 ... +176 °F)

Accuracy over temperature range: at +15 ... +25 °C (+59 ... +77 °F) ±0.2 °C (±0.36 °F) at 0 …+15 °C and +25 …+40 °C

(+32 ... +59 °F and +77 ...+104 °F) ±0.25 °C (±0.45 °F) at -40 ... 0 °C and +40 ... +80 °C

(-40 ... +32 °F and +104...+176 °F) ±0.4 °C (±0.72 °F)

Temperature sensor Pt1000 RTD 1/3 Class B IEC 751

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Table 11 Operating Environment Specifications

Property

Operating temperature range

Transmitter body, no display

Transmitter body, with display

HMP110 probe

Storage temperature range

Electromagnetic compatibility


-40 ... +60 °C (-40 ... +140 °F)

-20 ... +60 °C (-4 ... +140 °F)

-40 ... +80 °C (-40 ... +176 °F)

-50 ... +70 °C (-58 ... +158 °F)

EN 61326-1:2006 Electrical equipment for measurement, control and laboratory use - EMC requirements - Basic immunity test requirements.

EN 55022:2006 + Am 1:2007

Information technology equipment -

Radio disturbance characteristics -

Limits and methods of measurement. Class B.

Table 12 Inputs and Outputs

Property

Two-wire output signal

External loop voltage


4 ... 20 mA (loop powered)

10 ... 30 VDC (R

L

= 0 ohms)

20 ... 30 VDC (R

L

< 500 ohms)

±0.1% of full scale output current Max. additional error caused by the analog outputs after calibration at +20

°C ambient temperature

Temperature dependence of the analog outputs

±0.005 %/°C full scale output current

Table 13 Mechanical Specifications

Property Description / Value

Material

Transmitter housing PBT plastic

Display window

Probe body

Probe grid filter

PC plastic

Chrome coated aluminum

Chrome coated ABS plastic

Housing classification

Connections

Current loop outputs Screw terminals 0.5 ... 1.5 mm²

Probe interface

Probe cable lengths

IP65 (NEMA 4)

4-pin M8 female panel connector

3 m, 5 m, 10 m, cables can be cascaded up to 50 m

Display (optional)

Weight (Wall model, including probe)

Weight (10m cable model)

128x64 resolution full graphics

B&W display without backlight

270 g

540 g

76 __________________________________________________________________ M211244EN-A


Options and Accessories

Table 14 Options and Accessories

HMP110 probe for HMT120

HMP110R replacement probe for

HMT120

HMP110 – separate order form

HMP110R – separate order form

HMP110T temperature only probe for HMT120

Constant output probe

Humidity sensor

Probe mounting flange

Probe mounting clamps, 10 pcs

Sensor protection

Plastic grid filter

HMP110T – separate order form

HMP110REF – separate order form

Humicap180R

226061

226067

DRW010522SP

Plastic grid with membrane filter DRW010525

Stainless steel sintered filter HM46670SP

Probe cable 3 m

Probe cable 5 m

Probe cable 10 m

Radiation shield

Probe installation kit for DTR502

Rain shield with installation kit

Duct installation kit

HMI41 connection cable

HM70 connection cable

Service cable for PC, USB

HMT120Z300

HMT120Z500

HMT120Z1000

DTR502B

210623

215109

215619

25917ZZ

211339

219685

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Transmitter Dimensions

1011-158

Figure 21 Dimensions of the Fixed Probe Model in mm (inches)

78 __________________________________________________________________ M211244EN-A


1011-159

Figure 22 Dimensions of the Remote Probe Model in mm (inches)

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80 __________________________________________________________________ M211244EN-A

Appendix A ______________________________________________________ Calculation Formulas

APPENDIX A

CALCULATION FORMULAS

This appendix contains the formulas used for the calculated output quantities.

HMT120 transmitter receives relative humidity and temperature from the

HMP110 probe. From these values dewpoint, frostpoint, absolute humidity, mixing ratio, enthalpy, wet bulb temperature, saturation vapor pressure and vapor pressure in normal pressure are calculated using the following equations.

Symbols:

T d

= Dewpoint (°C)

P w

= Water vapor pressure (hPa)

P ws

= Saturation vapor pressure (hPa)

RH = Relative humidity (%)

x

= Mixing ratio (g/kg)

p

= Atmospheric pressure (hPa)

a

= Absolute humidity (g/m3)

T

= Temperature

h

Tw

=

=

Enthalpy (kJ/kg)

Wet bulb temperature (°C)

Tdf

= Dew/frostpoint temperature (°C)

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Dewpoint Temperature

The dewpoint temperature (Td) of a moist air sample is the temperature to which the sample must be cooled to reach saturation with respect to liquid water.

Dewpoint temperature is calculated using:

T d



T n

log





m

P w

A







1

(1)

P w

is the water vapor pressure (see the equation below). The parameters

A, m, and T

n

depend on temperature according to the following table:

T A m Tn

… 0 °C 6.119866 7.926104 250.4138

0 ... 50 °C

50 ... 100 °C

6.1078

5.9987

7.5000

7.3313

237.30

229.10

100 ... 150 °C

150 ... °C

5.8493

6.2301

7.2756

7.3033

225.00

230.00

Dew/frostpoint Temperature

Dew/frostpoint temperature uses frostpoint calculation when the dewpoint is below 0 °C. Frostpoint is the temperature at which the air is saturated with respect to water vapor over an ice surface.

T d



0



T df



T d

T d



0



T df



T n

log





m

P w

A







1

(2)

P w

is the water vapor pressure (see the equation below). The parameters

A, m, and T

n

depend on temperature according to the following table:

Td A m Tn

… 0 °C 6.1134 9.7911 273.47

82 __________________________________________________________________ M211244EN-A


Mixing Ratio

The mixing ratio (mass of water vapour/mass of dry gas) is calculated using:

x



B



P w p-P w



g /

kg



(3)

where:

B = 621.9907 g/kg

The value of B depends on the gas. 621.9907 g/kg is valid for air.

Absolute Humidity

Absoute humidity is defined as the mass of water vapour in a certain volume. If ideal gas behaviour is assumed the absolute humidity can be calculated using:



g

/

m

3



(4)

a



C





T



P w

273 .

15

 where:

C = 216.679 gK/J

Enthalpy

Enthalpy is the sum of the internal energy of a thermodynamic system.

It can be calculated from mixing ratio using:

h



T



( 1 .

01



0 .

00189



x

)



2 .

5



x



kJ /

kg



(5)

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Saturation Vapor Pressure

The saturation vapor pressure (P

ws

) is the equilibrium water vapor pressure in a closed chamber containing liquid water. It is a function only of temperature, and it indicates the maximum amount of water that can exist in the vapor state.

The water vapor saturation pressure P

ws

is calculated by using two equations (6 and 7):

 

T



i

3





o

C i

T i

where

T = Temperature in K

Ci = coefficients

C0 = 0.49313580

C1 = -0.46094296 * 10-2

C2 = 0.13746454 * 10-4

C3 = -0.12743214 * 10-7

  (6) ln

P ws



i

3



 

1

b i



i



b

4 ln

 where

bi = Coefficients

b-1 = -0.58002206 * 104

b0 = 0.13914993 * 101

b1 = -0.48640239 * 10-1

b2 = 0.41764768 * 10-4

b3 = -0.14452093 * 10-7

b4 = 6.5459673

(7)

84 __________________________________________________________________ M211244EN-A


Water Vapor Pressure

Vapor pressure refers to the vapor pressure of water in air or other gas.

Water vapor has a partial pressure Pw which is part of the total pressure of the gas.

The water vapor pressure is calculated using:

P w



RH



P ws

100

 

(8)

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86 __________________________________________________________________ M211244EN-A

Appendix A __________________________________________________________________INDEX

INDEX

A

Active Errors

Analog Output

Analog Output Error Levels

69

Restoring 48

Firmware Version

Fixed and Remote Probe Models 14

8, 54, 58, 62, 77

HMT120

Analog Output Error Notification

Analog Output Quantity and Scaling

73 Dimensions 78

General Information 7

Analog Output Status

13

Reset 48

Analog Outputs HMT120H 13

HMT120T 13

®

HUMICAP

C

Calibration Commands

Calibration Information

37

Introduction 13

Replacing 51

Humidity and Temperature Transmitter

Command List

Commands

Calibrate 37

Component Board 24 Duct 20

14

Connections 24

L

Continuous Outputting

14, 24

Stop 36

M

D

Device Information

Displayed Quantities

31

Maintenance 51

Measurement Parameters

Configuration 41

E

Show 45

O

Environmental Parameters

Operation 27

Options 14, 16, 77

Error Codes

F

Factory Settings

71 Show 46

Output Interval

Set 36

Show 36

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Output quantities

Output Unit

13 Serial Line Operation

Configuration 40

35

P

Probe Mounting Clamp

Probe Mounting Flange

23

22

Set 40

Show 40

Service Port

Settings

27

Probe RH

Restore Factory Calibration

Probe T

Restore Factory Calibration

38

39

Restoring 48

Saving 47

System Information

Show 35

PuTTY 28

T

Q

Quantity

Technical Data

Technical Support

75

73

R

Show available

Radiation Shield

32 Calibrate 38

Terminal Application Settings 28

Terminal Echo

Set 40

Rain Shield

Reading Output

Transmitter

Troubleshooting 71

Recycling 9

USB Cable

S

Driver installation

Serial Commands

Serial Interface Mode

30

W

27

Show 41

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