Vaisala HMT120 User Manual
USER'S GUIDE
Vaisala HUMICAP® Humidity and
Temperature Transmitter Series
HMT120
M211244EN-B
PUBLISHED BY
Vaisala Oyj Phone (int.): +358 9 8949 1
P.O. Box 26 Fax: +358 9 8949 2227
FI-00421 Helsinki
Finland
Visit our Internet pages at www.vaisala.com.
© Vaisala 2013
No part of this manual may be reproduced, published or publicly displayed in any form
or by any means, electronic or mechanical (including photocopying), nor may its
contents be modified, translated, adapted, sold or disclosed to a third party without prior
written permission of the copyright holder. Translated manuals and translated portions
of multilingual documents are based on the original English versions. In ambiguous
cases, the English versions are applicable, not the translations.
The contents of this manual are subject to change without prior notice.
This manual does not create any legally binding obligations for Vaisala towards
customers or end users. All legally binding obligations and agreements are included
exclusively in the applicable supply contract or the General Conditions of Sale and
General Conditions of Service of Vaisala.
_________________________________________________________________________________
Table of Contents
CHAPTER 1
GENERAL INFORMATION ............................................................................ 5
About This Manual ................................................................... 5
Contents of This Manual ....................................................... 5
Version Information ............................................................... 6
Related Manuals ................................................................... 6
Documentation Conventions ................................................. 6
Safety ......................................................................................... 7
ESD Protection ...................................................................... 7
Recycling .................................................................................. 7
Regulatory Compliances ......................................................... 8
Patent Notice ............................................................................ 8
Trademarks ............................................................................... 8
License Agreement .................................................................. 8
Warranty .................................................................................... 8
CHAPTER 2
PRODUCT OVERVIEW .................................................................................. 9
Introduction to the HMT120 Humidity and Temperature
Transmitter ................................................................................ 9
Accessories ......................................................................... 10
Fixed and Remote Probe Models........................................ 10
Optional Display .................................................................. 10
Interchangeable Probe ........................................................ 10
Constant Output Probe ....................................................... 11
Transmitter Components ..................................................... 12
CHAPTER 3
INSTALLATION ............................................................................................ 13
Opening the Transmitter Cover ............................................ 13
Mounting ................................................................................. 14
Wall Mounting...................................................................... 14
Installation with Rain Shield ................................................ 15
Installation with Radiation Shield ........................................ 16
Duct Installation Kit ............................................................. 17
Probe Assembly with Duct Installation Kit ..................... 18
Drilling Instructions for Duct Installation Kit ................... 18
Probe Mounting Flange ....................................................... 19
Probe Mounting Clamp ....................................................... 20
Connections ............................................................................ 21
CHAPTER 4
SERVICE PORT ........................................................................................... 23
Using the Service Port ........................................................... 23
Installing the Driver for the USB Cable ............................... 23
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User's Guide _______________________________________________________________________
Terminal Application Settings .............................................. 24
List of Serial Commands ....................................................... 26
Device Information and Status .............................................. 27
Show Device Information..................................................... 27
Set/Show Available Quantities ............................................ 28
Set/Show Calibration Date .................................................. 28
Set/Show Calibration Information ........................................ 29
Show Analog Output Status ................................................ 30
Show System Information ................................................... 31
Show Firmware Version ...................................................... 31
Serial Line Output Commands .............................................. 31
Start Continuous Outputting ................................................ 31
Stop Continuous Outputting ................................................ 32
Set/show Output Interval ..................................................... 32
Output a Reading Once ....................................................... 32
Calibration Commands .......................................................... 33
Calibrate Humidity Measurement ........................................ 33
Restore Probe RH Factory Calibration ................................ 34
Calibrate Temperature Measurement ................................. 34
Restore Probe T Factory Calibration ................................... 35
Calibrate Analog Output ...................................................... 35
Configuring Serial Line Operation ........................................ 36
Set/Show Serial Line Settings ............................................. 36
Set/Show Terminal Echo ..................................................... 36
Set/Show Serial Interface Mode .......................................... 37
Configuring Measurement Parameters ................................ 37
Set/Show Environmental Parameters ................................. 37
Configuring Analog Output ................................................... 38
Set/show Analog Output Error Levels ................................. 38
Set/show Analog Output Quantity and Scaling ................... 38
Test Analog Outputs ............................................................ 40
Other Commands.................................................................... 41
Set/show Displayed Quantities ............................................ 41
Set/show Output Formatting ................................................ 42
Display Command List......................................................... 43
Display Active Errors ........................................................... 43
Save Changed Settings ....................................................... 43
Restore Saved Settings ....................................................... 44
Reset Transmitter ................................................................ 44
Restore Factory Settings ..................................................... 44
Set/show Output Unit ........................................................... 45
CHAPTER 5
MAINTENANCE ............................................................................................ 47
Replacing the HUMICAP® Sensor ......................................... 47
Fixed and Remote Probe Models ........................................ 47
Removing and Fastening the Probe ..................................... 48
Fixed Probe Model .............................................................. 48
Remote Probe Model ........................................................... 49
Calibration and Adjustment ................................................... 50
HMT120 Push-Button Calibration ........................................ 50
Humidity and Temperature Adjustment ............................... 51
Adjustment with HM70......................................................... 54
2 ____________________________________________________________________ M211244EN-B
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Field Checking and Adjustment Using a Calibrated
Reference Probe ............................................................ 55
One-Point Adjustment Using a Calibrator ...................... 55
Two-Point Adjustment Using a Calibrator ...................... 56
LiCl-NaCl Adjustment ..................................................... 57
Temperature Field Check and Adjustment by Using a
Calibrated Reference Probe .......................................... 58
Adjustment with HMI41 ....................................................... 59
Connections and Selecting the Calibrator Function ....... 60
Offset and Gain Adjustments ......................................... 61
HMI41 as a Reference Meter .................................... 62
HMI41 as a Terminal ................................................. 63
Troubleshooting ............................................................. 64
Analog Output Tests .............................................................. 65
CHAPTER 6
TROUBLESHOOTING ................................................................................. 67
Error Codes ............................................................................. 67
Solving Typical Problems...................................................... 68
Analog Output Error Notification .......................................... 69
Technical Support .................................................................. 69
CHAPTER 7
TECHNICAL DATA ...................................................................................... 71
Options and Accessories ...................................................... 73
Transmitter Dimensions ........................................................ 74
APPENDIX A
CALCULATION FORMULAS ...................................................................... 77
Dewpoint Temperature .......................................................... 78
Dew/frostpoint Temperature ................................................. 78
Mixing Ratio ............................................................................ 79
Absolute Humidity .................................................................. 79
Enthalpy .................................................................................. 79
Saturation Vapor Pressure .................................................... 80
Water Vapor Pressure ............................................................ 81
Accuracies of Calculated Variables ..................................... 81
Accuracy of Dewpoint Temperature °C ............................... 81
Accuracy of Mixing Ratio g/kg (Ambient Pressure 1013
mbar) ................................................................................... 81
Accuracy of Wet Bulb Temperature °C ............................... 82
Accuracy of Absolute Humidity g/m³ ................................... 82
INDEX ........................................................................................................... 83
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List of Figures
Figure 1 HMT120 Components .............................................................. 12
Figure 2 Opening the Transmitter Cover ................................................ 13
Figure 3 HMT120 Wall Mounting ............................................................ 14
Figure 4 HMT120 Installation with Rain Shield ....................................... 15
Figure 5 Installation of the Probe with Radiation Shield ......................... 16
Figure 6 Probe Installation with the Duct Installation Kit ........................ 17
Figure 7 Assembly of the Probe with Duct Installation Kit ...................... 18
Figure 8 Drilling Instructions ................................................................... 18
Figure 9 Optional Probe Mounting Flange .............................................. 19
Figure 10 Optional Probe Mounting Clamp .............................................. 20
Figure 11 HMT120 Component Board ...................................................... 21
Figure 12 Isolated Current-Loop Wiring .................................................... 22
Figure 13 PuTTY Terminal Application ..................................................... 25
Figure 14 Removing the Humidity Probe (Fixed Probe Model) ................ 48
Figure 15 Removing the Humidity Probe (Remote Probe Model) ............ 49
Figure 16 Adjustment Buttons .................................................................. 50
Figure 17 Location of the MI70 Probe and Cable Connector Ports .......... 54
Figure 18 Example of the MI70 Adjustment Menu ................................... 56
Figure 19 Example of the MI70 Adjustment Mode Graph Display............ 56
Figure 20 Location of the HMI41 Calibration Connector .......................... 59
Figure 21 HMT120 Output Current Measurement .................................... 65
Figure 22 Dimensions of the Fixed Probe Model in mm (inches) ............. 74
Figure 23 Dimensions of the Remote Probe Model in mm (inches) ......... 75
List of Tables
Table 1 Manual Revisions ....................................................................... 6
Table 2 Related Manuals ......................................................................... 6
Table 3 Wiring Table .............................................................................. 22
Table 4 Default Serial Interface Setting ................................................. 24
Table 5 Serial Port Commands ............................................................. 26
Table 6 Common Problems During Adjustment and Their Remedies .. 64
Table 7 Error Codes and Texts ............................................................. 67
Table 8 Troubleshooting Table .............................................................. 68
Table 9 Relative Humidity Measurement Specifications ....................... 71
Table 10 Temperature Measurement Specifications ............................... 71
Table 11 Operating Environment Specifications ..................................... 72
Table 12 Inputs and Outputs ................................................................... 72
Table 13 Mechanical Specifications ........................................................ 72
Table 14 Options and Accessories .......................................................... 73
4 ____________________________________________________________________ M211244EN-B
Chapter 1 _________________________________________________________ General Information
CHAPTER 1
GENERAL INFORMATION
This chapter provides general notes for the manual and HMT120 Series.
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:
- Chapter 1, General Information, This chapter provides general notes
for the manual and HMT120 Series.
- Chapter 2, Product Overview, introduces the features, components and
accessories of the HMT120 Series.
- Chapter 3, Installation, provides you with information that is intended
to help you install the HMT120
- Chapter 4, Service Port, describes the service port of the HMT120.
- Chapter 5, Maintenance, provides information that is needed in basic
maintenance of HMT120.
- Chapter 6, Troubleshooting, describes error messages and analog
output error behavior, troubleshooting for possible problems, and
provides contact information for technical support
- Chapter 7, Technical Data, provides the technical data of the
HMT120.
- Appendix A, Calculation Formulas, contains the formulas used for the
calculated output quantities.
- INDEX
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User's Guide _______________________________________________________________________
Manual Code
Description
M211244EN-B
June 2013. This version. New probe options added.
Installation and operating instructions updated.
M211244EN-A
November 2010. First version.
Manual Code
Manual Name
M210185EN
Humidity Calibrator HMK15 User's Guide
M210297EN
Hand-held Humidity and Temperature Meter HM70
User's Guide
M210316EN
HMI41 Indicator and HMP41/45/46 Probes
Operating Manual
M211060EN
HMP60 and HMP110 Series Probe User's Guide
Version Information
Table 1 Manual Revisions
Related Manuals
Table 2 Related Manuals
WARNING
CAUTION
NOTE
Documentation Conventions
Throughout the manual, important safety considerations are highlighted
as follows:
Warning alerts you to a serious hazard. If you do not read and follow
instructions very carefully at this point, there is a risk of injury or even
death.
Caution warns you of a potential hazard. If you do not read and follow
instructions carefully at this point, the product could be damaged or
important data could be lost.
Note highlights important information on using the product.
6 ____________________________________________________________________ M211244EN-B
Chapter 1 _________________________________________________________ General Information
Do
or lead to malfunction.
Recycle all applicable material.
Dispose of the unit according to statutory regulations. Do not dispose of
with regular
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
not modify the unit. Improper modification can damage the product
ESD Protection
Electrostatic Discharge (ESD) can cause immediate or latent damage to
electronic circuits. Vaisala products are adequately protected against
ESD for their intended use. It is possible to damage the product,
however, 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 an ESD workbench is not available, ground yourself to the
equipment chassis with a wrist strap and a resistive connection cord.
- If you are unable to take either of the above precautions, touch a
conductive part of the equipment chassis with your other hand before
touching ESD sensitive components.
- Always hold component boards by the edges and avoid touching the
component contacts.
Recycling
household refuse.
VAISALA _________________________________________________________________________ 7
User's Guide _______________________________________________________________________
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.
Warranty
Visit our Internet pages for standard warranty terms and conditions:
www.vaisala.com/warranty.
Please observe that any such warranty may not be valid in case of
damage due to normal wear and tear, exceptional operating conditions,
negligent handling or installation, or unauthorized modifications. Please
see the applicable supply contract or Conditions of Sale for details of the
warranty for each product.
8 ____________________________________________________________________ M211244EN-B
Chapter 2 ___________________________________________________________ Product Overview
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features, components and accessories of the
HMT120 Series.
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
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 RL <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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Only probes that have a compatible digital output (VDIGI mode) can be
used with HMT120 transmitter. Compatible probes have the lette
the first letter in their order code. The order code is written on the probe.
Accessories
The following accessories are optionally available:
- Duct installation kit
- Rain shield with 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 (3/5/10/20 m)
cable lengths. All extension cables can be easily cascaded in order to
obtain longer reach; see Options and Accessories on page 73.
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).
r "V" as
10 ___________________________________________________________________ M211244EN-B
Chapter 2 ___________________________________________________________ Product Overview
The transmitter goes to the error state for a short time when the probe is
changed. This is normal.
Constant Output Probe
The constant output probe HMP110REF 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.
NOTE
4. After checking the outputs, disconnect the constant output probe
and reconnect the original probe.
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The following numbers refer to Figure 1 above:
1 = Transmitter enclosure
2 = Cable bushing: cable gland, cable grommet, or conduit fitting.
3 = Probe cable
4 = HMP110 probe
5 = Plastic grid filter
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.
1007-001
Figure 1 HMT120 Components
See section Options and Accessories on page 73 for accessory parts and
their numbers.
12 ___________________________________________________________________ M211244EN-B
Chapter 3 ________________________________________________________________ Installation
CHAPTER 3
INSTALLATION
This chapter provides you with information that is intended to help you
install the HMT120.
Opening the Transmitter Cover
1. If the transmitter is not mounted already, hold it against a flat
surface.
2. Push on the cover with your thumb, and pull the bottom part of the
cover towards yourself.
1301-019
Figure 2 Opening the Transmitter Cover
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User's Guide _______________________________________________________________________
Select the size and type of the fastening
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 b
of the enclosure. The diameter of the fastening screws is typically
between 3.5 and 4
Mounting
Wall Mounting
1. Remove the transmitter cover. See section Opening the Transmitter
Cover on page 13.
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 3 HMT120 Wall Mounting
CAUTION
It is possible to damage the display when tightening the screws, as there
is not much room between the upper fastening holes and the exposed
display component. Be particularly careful when using a cordless drill.
NOTE
e used without sacrificing the ingress protection (IP) class
mm.
14 ___________________________________________________________________ M211244EN-B
screws according to the wall
Chapter 3 ________________________________________________________________ Installation
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.
1011-150
Figure 4 HMT120 Installation with Rain Shield
1. Fasten the metal mounting plate to the wall or pole with screws
(see Figure 4 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.
VAISALA ________________________________________________________________________ 15
User's Guide _______________________________________________________________________
The following numbers refer to Figure 5 above:
1 = DTR504
2 = Probe
3 = Plastic nut
4 = Installation support (part no. 227777)
6 = Probe
Installation with Radiation Shield
DTR504 with probe installation kit includes a rain/solar radiation shield
DTR504 and a plastic installation support for the humidity probe. Vaisala
order code: DTR504A. If you already have the DTR504 shield and need
only the installation support for the probe, it is available with Vaisala
order code 227777.
1. Fasten the probe (item 2 in Figure 5 below) to the installation
support with a cable tie (item 5).
2. Insert and attach the support to the radiation shield by tightening
the plastic nut (3).
3. Attach the entire radiation shield/probe assembly to a pole mast
(pole mast diameter: 30 ... 60 mm/1.2 ... 2.3") with a U-bolt and a
support arm.
1303-034
Figure 5 Installation of the Probe with Radiation Shield
16 ___________________________________________________________________ M211244EN-B
Chapter 3 ________________________________________________________________ Installation
The following explanations refer to Figure 6 above:
1 = Tension screw
Distance L can be adjusted and locked in place with the tension screw.
24
L
1
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 18 for details.
0505-176
Figure 6 Probe Installation with the Duct Installation Kit
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The following numbers refer to Figure 7 above:
1 = HMP110
2 = Duct installation kit
3 = Probe cable
The following numbers refer to Figure 8 above:
1 = Mounting screw
2 = Tension screw
3 = HMP110 assembled in duct installation kit plastic pipe
2
1
3
42
1
2
3
Ø24
Ø3.2
Probe Assembly with Duct Installation Kit
0505-177
Figure 7 Assembly of the Probe with 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
0505-178
Figure 8 Drilling Instructions
18 ___________________________________________________________________ M211244EN-B
Chapter 3 ________________________________________________________________ Installation
The coaxial silicone plug that is delivered with the flange is not
for use with the probe cable of the HMT120.
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
0911-109
suitable
Figure 9 Optional Probe Mounting Flange
VAISALA ________________________________________________________________________ 19
User's Guide _______________________________________________________________________
Attaching the probe mounting clamp to a conductive wall material
should be
supplies and uncontrolled earth current loops could cause measurement
errors or even damage to the HMT120 transmitter.
Probe Mounting Clamp
The optional mounting clamp 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. You can order a single
clamp (Vaisala order code 225501) or a set of 10 clamps (226067).
Installing the entire probe in the measurement environment prevents heat
conduction to the sensor, and is the recommended installation method.
CAUTION
Figure 10 Optional Probe Mounting Clamp
avoided, since the potential galvanic connection to the power
1001-138
20 ___________________________________________________________________ M211244EN-B
Chapter 3 ________________________________________________________________ Installation
The following numbers refer to Figure 11 above:
1 = Optional LCD display
2 = Adjustment buttons
3 = Indicator LEDs
4 = Service port
5 = Field wire terminals
2 4 1 5 3
SHLD
CH1 - CH1+
CH2 - CH2+
SERVICE PORT
ADJ + -
RH T C A L
2 4 1 5 3
SHLD
CH1 - CH1+
CH2 - CH2+
SERVICE PORT
ADJ + -
RH T C A L
Connections
1011-151
Figure 11 HMT120 Component Board
1. Remove the transmitter cover. See section Opening the Transmitter
Cover on page 13.
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 12 and in Table 3 on page
22. Suitable wire size is between 0.5 mm2 and 1.5 mm2.
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User's Guide _______________________________________________________________________
If an isolated output is required with current outputs, both channels
require their own power supply. CH1 is always required to be
because CH1 is the main output, and the transmitter will not operate if
only CH2 is connected.
Terminal
Current Output (2-Wire, CH2 Isolated)
1
Cable shield (optional)
2
CH1- (signal and power supply -)
3
CH1+ (signal and power supply +)
4
CH2- (signal and power supply -)
5
CH2+ (signal and power supply +)
NOTE
powered
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.
1011-152
Figure 12 Isolated Current-Loop Wiring
Table 3 Wiring Table
The numbers 1 ... 5 in the first column of the wiring table refer to Figure
12 above.
22 ___________________________________________________________________ M211244EN-B
Chapter 4 _______________________________________________________________ Service Port
The service port is intended for short
permanent installation, use the ana
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.
CHAPTER 4
SERVICE PORT
This chapter describes the service port of 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
-term use such as calibration. For
log output.
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 service cable into use, you must install the
provided USB driver on your PC.
1. Check that the USB service cable is not connected. Disconnect the
cable if you have already connected it.
2. Insert the media that came with the cable, or download the latest
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.
VAISALA ________________________________________________________________________ 23
User's Guide _______________________________________________________________________
Property
Value
Baud rate
19200
Parity
None
Data bits
8
Stop bits
1
Flow control
None
4. After the driver has been installed, connect the USB service cable
to a USB port on your PC. Windows will detect the new device,
and use the driver automatically.
5. The installation has reserved a COM port for the cable. Verify the
port number, and the status of the cable, using the Vaisala USB
Instrument Finder program that has been installed in the
Windows Start menu.
Windows will recognize each individual cable as a 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 Programs and Features menu in the Windows Control Panel.
In Windows XP and earlier Windows versions the menu is called Add or
Remove Programs.
Terminal Application Settings
The default settings of the HMT120 serial interface are presented in
Table 4.
Table 4 Default Serial Interface Setting
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.
3. Select the Serial settings category, and check that the correct COM
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.
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If PuTTY is unable to open the serial port you
an error message instead. If this happens, restart PuTTY and check the
settings.
4. Check that the other serial settings are correct for your connection,
and change if necessary. Flow control should be set to None unless
you have a reason to change it.
5. Click the Open button to open the connection window and start
using the serial line.
NOTE
selected, it will show you
6. You may need to adjust the Local echo setting in the Terminal
category to see what you are typing on the serial line. To access the
configuration screen while a session is running, click the right
mouse button over the session window, and select Change
Settings... from the pop-up menu.
Figure 13 PuTTY Terminal Application
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