Vaisala HPP272 User Manual

M211972EN-B

User Guide

Vaisala PEROXCAPâ Hydrogen Peroxide,

Humidity and Temperature Probe

HPP272

PUBLISHED BY

Vaisala Oyj
Street address: Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
Mailing address: P.O. Box 26, FI-00421 Helsinki, Finland
Phone: [phone]

Visit our Internet pages at www.vaisala.com.

© Vaisala 2017

No part of this manual may be
reproduced, published or publicly
displayed in any form or by any
means, electronic or mechanical
(including photocopying), nor
may its contents be modified,
translated, adapted, sold or
disclosed to a third party without
prior written permission of the
copyright holder. Translated
manuals and translated portions
of multilingual documents are
based on the original English
versions. In ambiguous cases, the
English versions are applicable,
not the translations.

The contents of this manual are
subject to change without prior
notice.

Local rules and regulations may
vary and they shall take
precedence over the information
contained in this manual. Vaisala
makes no representations on this
manual’s compliance with the

local rules and regulations
applicable at any given time, and
hereby disclaims any and all
responsibilities related thereto.

This manual does not create any
legally binding obligations for
Vaisala towards customers or end
users. All legally binding
obligations and agreements are
included exclusively in the
applicable supply contract or the
General Conditions of Sale and
General Conditions of Service of
Vaisala.

This product contains software
developed by Vaisala or third
parties. Use of the software is
governed by license terms and
conditions included in the
applicable supply contract or, in
the absence of separate license
terms and conditions, by the
General License Conditions of
Vaisala Group.

Table of Contents

Table of Contents

1. About This Document................................................................................... 5

1.1 Version Information..........................................................................................5

1.2 Related Manuals................................................................................................5

1.3 Documentation Conventions...........................................................................5

1.4 Trademarks........................................................................................................ 6

1.5 Patent Notice.....................................................................................................6

2. Product Overview........................................................................................... 7

2.1 Introduction to HPP272....................................................................................7

2.2 Basic Features and Options.............................................................................8

2.3 Safety..................................................................................................................8

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

2.5 Measured Parameters.......................................................................................9

2.5.1 Understanding Relative Humidity and Relative Saturation................ 10

2.6 Probe Filter........................................................................................................11

2.7 Chemical Purge.................................................................................................11

2.8 Environmental Compensation for Pressure..................................................12

2.9 Measurement Filtering Factor........................................................................12

2.10 Connectivity to Vaisala Insight Software......................................................12

2.11 Additional Features with Indigo Transmitters..............................................13

3. H2O2 Measurement....................................................................................... 14

3.1 Operating Principle of H2O2 Measurement.................................................. 14

3.2 Typical Applications........................................................................................16

3.3 Condensation Monitoring...............................................................................18

4. Installation.......................................................................................................20

4.1 Wiring...............................................................................................................22

4.2 Power Supply.................................................................................................. 23

4.3 Setting Probe in Analog or Digital Mode.....................................................23

5. Operation......................................................................................................... 25

5.1 Probe Start-Up................................................................................................25

5.2 Behavior at Exposure to H2O2.......................................................................25

5.3 H2O2 Concentration Reading When Not Exposed to H2O2.......................25

5.4 Modbus............................................................................................................ 26

5.5 Operation in Analog Mode............................................................................26

5.5.1 Analog Output Overrange Behavior.....................................................26

5.5.2 Triggering Purge in Analog Mode......................................................... 27

6. Vaisala Insight Software............................................................................ 28

6.1 Connecting to Insight Software....................................................................28

1

HPP272 User Guide M211972EN-B

7. Using Probe with Indigo Transmitters................................................. 29

7.1 Indigo Overview............................................................................................. 29

7.1.1 Wireless Configuration Interface Overview.........................................30

7.2 Attaching Probes.............................................................................................31

7.3 Connecting to Wireless Configuration Interface........................................ 32

7.4 Logging in to Wireless Configuration Interface..........................................33

8. Maintenance....................................................................................................34

8.1 Cleaning the Probe.........................................................................................34

8.1.1 Chemical Tolerance................................................................................. 34

8.2 Calibration and Adjustment.......................................................................... 35

9. Troubleshooting............................................................................................ 36

9.1 Problems and Their Possible Solutions........................................................36

9.2 Analog Output Error State............................................................................40

10. Technical Data................................................................................................. 41

10.1 Dimensions...................................................................................................... 43

10.2 Accessories.....................................................................................................44

Appendix A:

Modbus Reference........................................................................45

A.1 Default Communication Settings................................................................. 45

A.2 Function Codes...............................................................................................45

A.3 Data Encoding................................................................................................45

A.3.1 32-Bit Floating Point or Integer Format...............................................45

A.3.2 16-Bit Integer Format............................................................................. 46

A.4 Modbus Registers...........................................................................................46

A.4.1 Measurement Data Registers.................................................................47

A.4.2 Configuration Registers......................................................................... 48

A.4.3 Status Registers...................................................................................... 54

A.4.4 Device Identification Objects.................................................................56

A.4.5 Test Value Registers................................................................................ 57

A.5 Modbus Communication Examples..............................................................58

Warranty........................................................................................................................ 61

Technical Support...................................................................................................... 61

Recycling....................................................................................................................... 61

2

List of Figures

Figure 1 HPP272 Probe Parts...........................................................................................7

Figure 2 Eect of H2O and H2O2 on relative saturation (RS) and

relative humidity (RH).....................................................................................10

Figure 3 Operating principle of PEROXCAP measurement................................... 15

Figure 4 Example behavior of H2O2 concentration, relative

saturation (RS), and relative humidity (RH) in a

vaporized H2O2 bio-decontamination cycle (non-

condensing conditions)...................................................................................17

Figure 5 Example: RS behavior in dierent temperatures when

H2O2 concentration (500 ppm) and H2O concentration

(8850 ppm) are constant............................................................................... 18

Figure 6 Decontaminated space with dierent temperatures and

RS levels (H2O2 and H2O concentration evenly distributed)................19

Figure 7 Probe M12/5 Pins..............................................................................................22

Figure 8 Wiring Example for Connecting HPP272 to a PLC in

Analog Mode..................................................................................................... 23

Figure 9 Pins on the M12 male connector.................................................................. 24

Figure 10 Connecting Probe to Insight.........................................................................28

Figure 11 Attaching Probes to Indigo............................................................................31

Figure 12 Enabling and Accessing Indigo's Wireless Configuration

Interface..............................................................................................................32

Figure 13 Indigo Login View............................................................................................33

Figure 14 HPP272 Dimensions........................................................................................ 43

List of Figures

3

HPP272 User Guide M211972EN-B

List of Tables

Table 1 Document Versions..............................................................................................5

Table 2 Related Manuals....................................................................................................5

Table 3 Applicable Patents or Applications.................................................................6

Table 4 Available Parameters...........................................................................................9

Table 5 Measurement Performance..............................................................................41

Table 6 Inputs and Outputs............................................................................................42

Table 7 Mechanical Specifications............................................................................... 43

Table 8 Operating Environment....................................................................................43

Table 9 Spare Parts and Accessories.......................................................................... 44

Table 10 Default Modbus Serial Communication Settings...................................... 45

Table 11 Modbus Function Codes.................................................................................. 45

Table 12 16-bit Signed Integer Format Details........................................................... 46

Table 13 Modbus Measurement Data Registers (Read-Only).................................47

Table 14 Modbus Configuration Data Registers (Writable)....................................49

Table 15 Modbus Status Registers (Read-Only)........................................................ 54

Table 16 Error Codes in Register 0201
Table 17 Error Codes in Register 0203

Table 18 Device Identification Objects......................................................................... 56

Table 19 Test Value Registers...........................................................................................57

(32-bit)..................................................... 55

hex

(32-bit).................................................... 56

hex

4

Chapter 1 – About This Document

1. About This Document

1.1 Version Information

This document provides instructions for installing, using, and maintaining Vaisala PEROXCAPâ
Hydrogen Peroxide, Humidity and Temperature Probe HPP272.

Table 1 Document Versions

Document
Code

M211972EN-B December 2017 This document. Added description and Modbus registers for

M211972EN-A September 2017 First version.

Date Description

pressure compensation, removed restriction not to perform a
purge during H2O2 exposure, clarified operating system

requirements for Vaisala Insight software, clarified Indigo
200 transmitter compatibility with HPP272.

1.2 Related Manuals

Table 2 Related Manuals

Document Code Name

M211887EN Hydrogen Peroxide, Humidity and Temperature Probe HPP270 Series Quick

M211877EN Indigo 201 Analog Output Transmitter User Guide

Guide

1.3 Documentation Conventions

WARNING!

follow instructions carefully at this point, there is a risk of injury or even death.

Warning alerts you to a serious hazard. If you do not read and

CAUTION!

follow instructions carefully at this point, the product could be damaged or
important data could be lost.

Caution warns you of a potential hazard. If you do not read and

5

HPP272 User Guide M211972EN-B

Note highlights important information on using the product.

Tip gives information for using the product more eciently.

Lists tools needed to perform the task.

Indicates that you need to take some notes during the task.

1.4 Trademarks

Vaisalaâ, HUMICAPâ, and PEROXCAPâ are registered trademarks of Vaisala Oyj.

Indigo™ is a trademark of Vaisala Oyj.

All other product or company names that may be mentioned in this publication are trade
names, trademarks, or registered trademarks of their respective owners.

1.5

 Patent Notice

This product is protected by the following patents and patent applications and their
corresponding national rights:

Table 3 Applicable Patents or Applications

Issuing Oce Publication Number

European Patent Oce EP 3004868

State Intellectual Property Oce of the P.R.C. CN 105229463A

United States Patent and Trademark Oce US 20160084811

6

21 543

6

Chapter 2 – Product Overview

2. Product Overview

2.1 Introduction to HPP272

Vaisala PEROXCAPâ Hydrogen Peroxide, Humidity and Temperature Probe HPP270 series is
designed for demanding hydrogen peroxide bio-decontamination processes. The probes are
suitable for a variety of applications such as isolator, material transfer hatch, and room bio­decontamination.

Hydrogen Peroxide, Humidity and Temperature Probe HPP272 provides measurement for
vaporized H2O2 concentration, relative saturation, relative humidity, and temperature.

The H2O2 measurement is based on comparing the readings of two composite humidity
sensors to determine the vapor concentration of H2O2. The probes are easy to install with a
plug-in/plug-out M12/5 connection. The digital and analog output options include an RS-485

interface for Modbus communication and two current output channels.

The probe is not intended for safety level measurement.

The probe is not intended to be used in vacuum applications.

CAUTION!

always be powered on. When powered on, the PEROXCAP sensor is heated,
which permits using the probe in condensing H2O2 conditions, maintains

measurement performance, and lengthens the probe's lifetime. When the probe
is powered o, exposure to H2O2 condensation can break the PEROXCAP sensor

within a day, and the sensor will not recover.

When there is H2O2 in the probe's environment, the probe must

Figure 1 HPP272 Probe Parts

1 Yellow transport cap. Remove this cap

before using the probe.

2 Filter covering the sensor. The filter is

an essential part of the measurement
technology: do not remove the filter.

Filters are available as spare parts.

3 PEROXCAP sensor under the filter.
4 H2O2 and humidity probe.

5 Temperature probe.
6 5-pin M12 connector.

7

HPP272 User Guide M211972EN-B

More Information

‣

Dimensions (page 43)

‣

Operating Principle of H2O2 Measurement (page 14)

‣

Installation (page 20)

‣

Wiring (page 22)

2.2 Basic Features and Options

• Vaisala PEROXCAPâ H2O2 measurement technology with excellent long-term stability.

• Vaporized H2O2 measurement range 0 ... 2000 ppm.

• Relative saturation (RS) measurement range 0 ... 100 %RS.

• Relative humidity (RH) measurement range 0 … 100 %RH.

• Temperature (T) measurement range +5 ... +70 °C.

• Robust design allowing the probe to be installed directly in the process environment.
When powered on, the probe withstands H2O2 and H2O condensation. The probe also

withstands nitrogen gas.

• Protective

• Sensor heating to avoid condensation on the sensors.

• Chemical purge for optimized performance and lifetime.

• Pressure compensation for H2O2 concentration (ppm), H2O concentration (ppm), and
relative saturation (%RS) measurement.

• Digital output: RS-485 interface for Modbus communication.

• Analog output: 2 x 4 ... 20 mA (default).

• Easy plug-in, plug-out.

• Can be used as a stand-alone probe or with Vaisala Indigo 200 series transmitters.

• Can be connected to Vaisala Insight software for
temporary online monitoring.

filter over the sensors designed to withstand high air flow rates and turbulence.

configuration, diagnostics, and

More Information

‣

Technical Data (page 41)

2.3

 Safety

WARNING!

to minimize shock hazard.

WARNING!

has not been exposed to dangerous contamination, and is safe to handle
without special precautions.

8

Ground the product and verify installation grounding periodically

When returning a product for calibration or repair, make sure it

Chapter 2 – Product Overview

CAUTION!

Do not attempt to open the probe body. There are no user

serviceable parts inside the probe body.

2.4 ESD Protection

Electrostatic Discharge (ESD) can cause immediate or latent damage to electronic circuits.
Vaisala products are adequately protected against ESD for their intended use. However, it is
possible to damage the product by delivering an electrostatic discharge when touching,
removing or inserting any objects inside the equipment housing.

Avoid touching component contacts or connectors when working with the device.

2.5 Measured Parameters

Table 4 Available Parameters

Parameter Unit

Vaporized hydrogen peroxide concentration by
volume

Relative saturation (RS) (H2O + H2O2) %RS

Relative humidity (RH) (H2O) %RH

Temperature °C

Absolute hydrogen peroxide

Absolute humidity (H2O)

Water concentration by volume ppm

Water vapor pressure hPa

Water vapor saturation pressure hPa

ppm

mg/m

g/m

3

3

The probe provides both digital and analog outputs.

• In digital output mode, the probe outputs all the measurement parameters.

• In analog output mode, the probe outputs the readings of two measurement parameters
(one parameter in each analog output channel). These measurement parameters are
chosen at the time of ordering the probe, and you can change them using Insight
software and via Modbus. The probe is also compatible with Vaisala Indigo transmitters,
which provide the option of three analog output channels.

9

%RH%RS

00

100100

H2O

H2O

2

%RS %RH

0 0

100

100

H2O

1 2

HPP272 User Guide M211972EN-B

More Information

‣

Understanding Relative Humidity and Relative Saturation (page 10)

‣

Measurement Data Registers (page 47)

‣

Configuration Registers (page 48)

‣

Connectivity to Vaisala Insight Software (page 12)

‣

Setting Probe in Analog or Digital Mode (page 23)

2.5.1 Understanding Relative Humidity and Relative Saturation

Water and hydrogen peroxide have a very similar molecular structure, and they both aect the
humidity of the air in which they are present. HPP272 measurement makes a
between the humidity caused by both H2O2 vapor and water vapor, and the humidity caused

only by water vapor:

• Relative saturation is a parameter that indicates the humidity of the air caused by both
H2O2 vapor and water vapor. When relative saturation reaches 100 %RS, the vapor

mixture starts to condense.

• Relative humidity is a parameter that indicates the humidity of the air caused only by
water vapor.

dierence

Figure 2 Eect of H2O and H2O2 on relative saturation (RS) and relative humidity (RH)

Space without H2O2 vapor. When H2O2 vapor is not present, relative saturation equals

1

relative humidity.

2 Same space with H2O2 vapor introduced. Relative saturation is higher than relative

humidity.

During H2O2 bio-decontamination processes, it is often important to monitor the possibility of
condensation. For this purpose, it is not enough to know the level of relative humidity (RH),

because RH only indicates the humidity caused by water vapor. The possibility of
condensation is

aected by the combined humidity of H2O2 vapor and water vapor, which is

why you need to monitor relative saturation (RS).

10

Chapter 2 – Product Overview

2.6 Probe Filter

The white filter on the probe covers the PEROXCAP sensor. The filter is made of porous PTFE
that allows ambient air to reach the PEROXCAP sensor while protecting the sensor in strong or
turbulent air flow.

CAUTION!

broken, dirty, or removed altogether, measurement does not work as intended.

• Do not touch the
use clean gloves (rubber, cotton or similar material).

• Keep the

• Do not touch any parts under the filter. Touching parts under the filter may
damage the sensors.

More Information

‣

Problems and Their Possible Solutions (page 36)

2.7

 Chemical Purge

Chemical purge is a 4-minute process where the sensors are heated to remove possible
contamination. The purge is essential for the long-term performance and accuracy of the
probe in demanding H2O2 environments. During the purge, only temperature measurement is

available.

The purge is automatically performed:

• At probe start-up.

• At intervals (default 24 hours,
software, Modbus, or Indigo 200 transmitters). Purge is postponed by 30 minutes if H2O

is present or RH is not steady.

Purge is recommended at least every 24 hours of powered-on time, even if the probe has not
been continuously exposed to H2O2.

Optional: if needed, you can also trigger a purge manually with Modbus (in digital mode) or
pin #5 on the M12 connector (in analog mode).

The filter is an essential part of the measurement. If the filter is

filter with bare hands. If you need to touch the filter, always

filter free of any grease or oil.

configurable between 1 hour ... 1 week using Vaisala Insight

2

More Information

‣

Triggering Purge in Analog Mode (page 27)

‣

Operation in Analog Mode (page 26)

11

HPP272 User Guide M211972EN-B

2.8 Environmental Compensation for Pressure

When necessary, you can apply pressure compensation to improve the measurement accuracy
of the probe (probe software v.1.1.0 and later). The probe does not have on-board pressure
measurement, but a pressure reading from an external source can be used as a setpoint value
for compensation.

You can configure the pressure compensation parameters using Vaisala Insight software,
Modbus configuration registers, or an Indigo 200 transmitter.

By default, the pressure compensation is turned o. When the compensation is o, the probe
uses the default compensation value (1013.25 hPa).

Pressure compensation

• H2O2 concentration (ppm)

• H2O concentration (ppm)

• Relative saturation (%RS)

More Information

‣

Vaisala Insight Software (page 28)

‣

Configuration Registers (page 48)

2.9

 Measurement Filtering Factor

You can set a filtering factor that aects the speed at which the latest H2O2 and RS
measurements are integrated into the output of the probe. This allows averaging the output if

the measuring environment produces occasional exceptionally high or low readings.

filtering factor can be set either with Modbus configuration register 0308

The
Insight software, or an Indigo 200 transmitter.

By default, the
directly in the output, without any filtering. To apply filtering, enter a lower filtering factor to
include previous measurements in the calculation of measurement output. For example,
changing the
measurement (90%) and the previous measurement output (10%).

filtering factor to 0.9 results in an output that is a combination of the latest

aects the following parameters:

, Vaisala

hex

filtering factor is set to 1.0, which means the latest measurement is shown

More Information

‣

Configuration Registers (page 48)

2.10

 Connectivity to Vaisala Insight Software

The probe can be connected to Vaisala Insight software using a Vaisala USB cable (no.

242659). With the Insight software, you can:

• See device information and status.

12

Chapter 2 – Product Overview

• See real-time measurement.

• Configure serial communication settings, purge settings, filtering factor, and analog
output parameters and scaling.

More Information

‣

Connecting to Insight Software (page 28)

2.11 Additional Features with Indigo Transmitters

The probes are compatible with Vaisala Indigo 200 transmitters starting from Indigo
transmitter serial number N4650357 (Indigo 200 transmitter software version 1.3.2 or higher).
Connecting the probe to an Indigo transmitter provides a range of additional options for
outputs, measurement viewing, status monitoring, and

Examples of additional features available with Indigo transmitters include:

• 3.5” TFT LCD color display or non-display model with LED indicator

• Digital output or 3 analog outputs (depending on the transmitter model)

• 2 configurable relays

• Wireless browser-based configuration interface for mobile devices and computers (IEEE

802.11 b/g/n WLAN)

The selection of available additional features (for example, output and connectivity options)
varies depending on the Indigo transmitter model. For more information on Indigo
transmitters, see www.vaisala.com/indigo.

More Information

‣

Indigo Overview (page 29)

configuration interface access.

13

HPP272 User Guide M211972EN-B

3. H2O2 Measurement

3.1 Operating Principle of H2O2 Measurement

CAUTION!

always be powered on. When powered on, the PEROXCAP sensor is heated,
which permits using the probe in condensing H2O2 conditions, maintains

measurement performance, and lengthens the probe's lifetime. When the probe
is powered o, exposure to H2O2 condensation can break the PEROXCAP sensor

within a day, and the sensor will not recover.

PEROXCAPâ sensor technology works using measurements from two Vaisala HUMICAPâ
sensors. HUMICAP sensors guarantee quality and reliability, with their reputation for
repeatability, accuracy, excellent long-term stability, and negligible hysteresis – even in the
most demanding high-concentration H2O2 applications in atmospheric pressure.

HUMICAP sensor is a
polymer film is deposited between two electrodes. The film absorbs or releases vapor
according to humidity changes in the environment. As the humidity changes, the dielectric
properties of the polymer
instrument’s electronics measure the capacitance of the sensor and convert it into a humidity
reading.

PEROXCAP measurement uses two composite HUMICAP sensors, one with a catalytic layer
and one without. The catalytic layer catalyzes H2O2 from the vapor mixture. Therefore, the

HUMICAP sensor with this layer only senses water vapor, providing a measurement of partial
water pressure, i.e. relative humidity (RH). The sensor without the catalytic layer senses both
hydrogen peroxide vapor and water vapor in the air mixture. The
readings from these two sensors indicates the vapor concentration of H2O2.

When there is H2O2 in the probe's environment, the probe must

thin-film polymer sensor consisting of a substrate on which a thin

film change, and so does the capacitance of the sensor. The

dierence between the

14

H20

2

H20

2H20

0

2

2H20

2

H20

2

1

3

2

3

A B

Chapter 3 – H2O2 Measurement

Figure 3 Operating principle of PEROXCAP measurement

HUMICAP sensor with a catalytic layer (under the probe filter). This sensor only senses

A

water vapor.

B HUMICAP sensor without a catalytic layer (under the probe filter). This sensor senses the

air mixture with both hydrogen peroxide vapor and water vapor.

1 Catalytic layer over the thin film polymer. This layer catalyzes hydrogen peroxide into

water and oxygen and prevents it from entering the sensing polymer.

2 Thin film polymer between two electrodes.
3 Alumina substrate.

In addition to measuring vaporized H2O2 concentration, HPP272 provides measurement for
relative saturation, relative humidity, and temperature. Relative humidity (RH) is a parameter

that indicates the humidity value derived from water vapor only, whereas relative saturation
(RS) indicates the humidity percentage derived from water vapor and H2O2 vapor together.

When relative saturation reaches 100 %RS, the vapor mixture starts to condense.

15

HPP272 User Guide M211972EN-B

3.2 Typical Applications

The probe is not intended for safety level measurement.

The probe is not intended to be used in vacuum applications.

Vaporized hydrogen peroxide is used for bio-decontamination in several applications from
healthcare and pharmaceutics to food and beverage industry. Vaporized hydrogen peroxide is
an easy-to-use and eective bio-decontaminating agent that destroys the full spectrum of
biological contaminants including micro-organisms such as bacterial spores, mycobacteria,
and non-enveloped, non-lipid viruses. Bio-decontamination with vaporized hydrogen peroxide
is a low-temperature, environmentally friendly process that leaves no real residues, only water
vapor and oxygen. One of the
validated.

Common vaporized H2O2 bio-decontamination applications include isolators, transfer hatches,
closed Restricted Access Barrier Systems, and room bio-decontamination (for example, in

hospital environments, cleanrooms, decontamination tents, aircrafts, ships, and shipping
containers).

The bio-decontamination process typically has the following phases:

1. Optional dehumidification, where relative humidity is decreased to a desired level, for
example, by warming the space.

2. Conditioning, where vaporized H2O2 mixture is introduced into the space to be bio­decontaminated.

3. Decontamination, where H2O2 concentration is maintained at a desired level for a certain
time.

4. Aeration, where H2O2 is removed from the bio-decontaminated space.

benefits also is that the bio-decontamination process can be

16

100%

0%

More

Less

Cycle Phase

Aeration

Decontamination

Conditioning

Dehumidification

CONDENSATION POINT

RELATIVE
SATURATION (RS)

RELATIVE HUMIDITY (RH)

VAPORIZED HYDROGEN
PEROXIDE CONCENTRATION

Humidity

H2O

2

Concentration

Chapter 3 – H2O2 Measurement

Figure 4 Example behavior of H2O2 concentration, relative saturation (RS), and relative humidity
(RH) in a vaporized H2O2 bio-decontamination cycle (non-condensing conditions)

In the non-condensing bio-decontamination cycle example shown in Figure 4 (page 17):

• In the dehumidification phase, RH (and RS) decreases.

• When the conditioning phase starts, H2O2 concentration rises rapidly. There is also a rapid
increase in RS, which indicates the humidity caused by both H2O2 vapor and water vapor.
Because the generated H2O2 vapor is typically mixed with water vapor, RH also starts to
rise.

• In the decontamination phase, H2O2 concentration is steady. However, RS level rises slowly
close to 100 %RS, i.e. condensation point, due to rising RH level.

• In the aeration phase, H2O2 concentration, RS, and RH all decrease. When H2O

2

concentration is zero, RS equals RH.

The way your bio-decontamination process is designed
measure in dierent phases.

Depending on your bio-decontamination process, you may also want to either create or avoid
condensation during the conditioning and decontamination phases. In these phases, the air in
the bio-decontaminated space always contains both water and H2O2 vapor, which both

the possibility of condensation. To monitor and control whether and when condensation
forms, it is useful to know the combined humidity level of water vapor and H2O2 vapor: relative

aects which parameters you want to

saturation (RS). When relative saturation reaches 100 %RS, the vapor mixture starts to
condense.

aect

17

Temperature

Relative saturation

21 21.5 22 22.5

100

95

85

90

H2O2 = 500 ppm
H2O = 8850 ppm

HPP272 User Guide M211972EN-B

For condensation monitoring, choosing the right measurement location is very important. If
the bio-decontaminated space has surfaces with a lower temperature than where RS is
measured, condensation may start to form on those surfaces even before RS reaches 100 %RS
in the exact measurement location. To monitor the possibility of condensation, consider
installing the probe close to a surface where you suspect condensation may form.

More Information

‣

Understanding Relative Humidity and Relative Saturation (page 10)

‣

Installation (page 20)

3.3 Condensation Monitoring

H2O+H2O2 vapor mixture starts to condense when relative saturation (RS) reaches 100 %RS.

RS level is strongly aected by temperature: decreasing the temperature increases RS. If there
are temperature
that space even if the H2O+H2O2 vapor is evenly distributed.

dierences in the bio-decontaminated space, RS varies in dierent parts of

Figure 5 Example: RS behavior in dierent temperatures when H2O2 concentration (500 ppm) and
H2O concentration (8850 ppm) are constant

For condensation monitoring, this means that even if you measure < 100 %RS in one point, RS
may be 100 %RS in another, cooler point. The following
can vary in a decontaminated space according to temperature dierences.

18

figure shows an example of how RS

3

1

2

T= 21.5 ˚C
RS= 94.5 %RS

T= 22 ˚C
RS= 89.5 %RS

T= 21 ˚C
RS= 100 %RS

Chapter 3 – H2O2 Measurement

Figure 6 Decontaminated space with dierent temperatures and RS levels (H2O2 and H2O
concentration evenly distributed)

1 Center of the decontaminated space. The center is warmer than the wall and the window,

and the RS level is lower.

2 Wall of the decontaminated space. Because the wall is 0.5 °C cooler than the center of the

space, RS level is higher than in the center.

3 Window of the decontaminated space. The window is 1 °C cooler than the center of the

space, and RS = 100 %RS. Condensation starts to form on the window surface.

Condensation forms typically on surfaces, and first on surfaces that are cooler than the
surrounding air, such as:

To monitor the possibility of condensation by measuring RS, it is recommended to measure as
close as possible to places where condensation might occur.

• Walls

• Windows

• Supplies that have just been brought in the decontaminated space

19

HPP272 User Guide M211972EN-B

4. Installation

Accurate RH and RS measurement requires both humidity and temperature data from the
same environment. Install the H2O2 and humidity probe and the temperature probe in the

same measurement environment and temperature, approximately 6 ... 10 cm apart from each
other. Do not install the temperature probe directly above the H2O2 and humidity probe, as

moderate heat rising up from the H2O2 and humidity probe body may aect the ambient
temperature around the temperature probe.

When you choose the installation location for the probe, consider the following:

• Choose a location that represents the environment and process you want to measure.
Some factors may make a location unrepresentative of the process:

• Heat sources

• Materials that absorb H2O2, such as several plastics, rubbers and sealing materials

• Limited air

• The probes withstand bio-decontamination process conditions. For signal cables, you
must verify their suitability in the installation environment.

• The probes withstand high air flow rates.

• For condensation monitoring with relative saturation, consider installing the probe close
to a surface where condensation may form (typically, on cooler surfaces in the bio­decontaminated space).

• The probe is intended for use in atmospheric pressure. Do not install the probe in a
vacuum.

When there is H2O2 in the probe's environment, the probe must always be powered on. When
powered on, the PEROXCAP sensor is heated, which permits using the probe in condensing

H2O2 conditions, maintains measurement performance, and lengthens the probe's lifetime.

flow

20

CAUTION!

broken, dirty, or removed altogether, measurement does not work as intended.

• Do not touch the
use clean gloves (rubber, cotton or similar material).

• Keep the

• Do not touch any parts under the filter. Touching parts under the filter may
damage the sensors.

The filter is an essential part of the measurement. If the filter is

filter with bare hands. If you need to touch the filter, always

filter free of any grease or oil.

6 ... 10 cm

≤ 6 mm

Ø 40 mm

Ø 8 mm

1

2

4 cm

(recommended)

6 ... 10 cm

Chapter 4 – Installation

Example: Installation Through a Wall

A through-wall installation is
recommended especially in very harsh
processes.

Seal the lead-throughs on the metal body
of the probes.

The figure shows an example installation
using Vaisala spare part glands
(HPP272MOUNTINGSET1).

1 Nut for tightening the probe in place
2 Nut for mounting the gland

Example: Installation Entirely in Process Environment

Mount the H2O2 and humidity probe from
the probe body.

Mount the temperature probe from the
metal body. Note that the temperature
sensor is at the tip of the temperature
probe.

Let the signal cable hang loosely so that it
makes a bend. This prevents condensing
water from running to the probe along the
cable. Do not hang the probe by the signal
cable.

Make sure the signal cable you
use is suitable for your bio­decontamination process.

21

1

5

3

4

2

HPP272 User Guide M211972EN-B

4.1 Wiring

Figure 7 Probe M12/5 Pins

Pin # Function Notes Wire

1 Power supply With digital output: 15 ... 30 VDC

With analog output: 15 ... 25 VDC

When using analog outputs, it is recommended to
use a low supply voltage to minimize self-heating
and maximize measurement performance.

2 RS-485- or analog

output 2

3 Power and signal GND Blue

4 RS-485+ or analog

output 1

5 Output control and purge

trigger in analog mode

1) Wire colors apply to the following cables: 223263SP, 26719SP, 26720SP, 216546SP,
244669SP

2) The ordered parameters and scaling are shown in the calibration certificate delivered with
the probe.

Current output: 4 … 20 mA (default).

Current output: 4…20 mA (default)

Floating = RS-485

Grounded = Analog outputs

If you want to be able to trigger a purge manually in
the analog mode, do not connect pin #5
permanently to ground, but instead, use a relay or
similar to control the pin.

2)

2)

Color

1)

Brown

White

Black

Grey

22

PLC

DC power

supply

IN+ Current input
IN-

IN+ Current input
IN-

Relay/switch
control

+

-

Pin #1

(Power supply)

Pin #2

(Analog output 2)

Pin #3

(Power and signal

GND)

Pin #4

(Analog output 1 )

Pin #5

(Output control

and purge trigger

in analog mode)

HPP270 series

probe

Figure 8 Wiring Example for Connecting HPP272 to a PLC in Analog Mode

More Information

‣

Accessories (page 44)

‣

Triggering Purge in Analog Mode (page 27)

4.2

 Power Supply

Chapter 4 – Installation

Operating voltage range of the probe:

Maximum current consumption at 25 °C:

4.3

The probe has two output modes: digital mode (RS-485 using Modbus) and analog mode
(current output).

Both the digital output and analog output use the same pins in the M12 male connector (pins
#2 and #4), but only one of the output modes can be active at the same time. You select which
output mode is active with the output control pin #5.

• With digital output: 15 ... 30 VDC

• With analog output: 15 ... 25 VDC

• With digital output: 15 mA

• With analog output: 50 mA

• During purge: 200 mA

 Setting Probe in Analog or Digital Mode

23

1

5

3

4

2

HPP272 User Guide M211972EN-B

Figure 9 Pins on the M12 male connector

1. If the probe is powered on, power o the probe.

2. Select the output mode with pin #5:

a. To set the probe in analog mode, connect pin #5 to ground.

b. To set the probe in digital mode, leave pin #5

3. Power on the probe. The probe checks the state of pin #5 (grounded or floating) and goes
in the selected output mode.

floating.

24

Chapter 5 – Operation

5. Operation

5.1 Probe Start-Up

When powered on, the probe starts up within 2 seconds and the digital/analog outputs are
activated. The probe performs a start-up purge, which takes approximately 4 minutes. During
the purge, hydrogen peroxide, relative humidity, and relative saturation measurements are not
available. If the probe is in analog mode, analog outputs are in the error state (default: 3.6 mA)
during the purge.

Measurements from the outputs (digital and analog) will reach
minute warm-up period. For this reason, you should design your system so that it does not rely
on measurements from the probe during this time.

More Information

‣

Behavior at Exposure to H2O2 (page 25)

5.2

 Behavior at Exposure to H2O

specified accuracy after a 8½-

2

CAUTION!

always be powered on. When powered on, the PEROXCAP sensor is heated,
which permits using the probe in condensing H2O2 conditions, maintains

measurement performance, and lengthens the probe's lifetime. When the probe
is powered o, exposure to H2O2 condensation can break the PEROXCAP sensor

within a day, and the sensor will not recover.

When the bio-decontamination process starts and the probe is exposed to H2O2, the probe's
H2O2 concentration reading changes to > 0 ppm after approximately 20 ... 30 seconds. This
time is included in the response time of the probe.

5.3

 H2O2 Concentration Reading When Not

Exposed to H2O

The PEROXCAP sensor consists of two humidity sensors that have a minor dierence in
behavior when the humidity level changes. Because of this

reading may vary slightly (typically 0 … 3 ppm) when the probe is not exposed to H2O2. This
variation is normal and does not require any actions. If needed, you can hide the variation by

setting a low clipping limit with the Vaisala Insight software, Modbus
030C

, or an Indigo 200 transmitter. For example, if you set the low clipping limit to 3 ppm,

hex

any reading < 3 ppm is clipped to show 0 ppm.

When there is H2O2 in the probe's environment, the probe must

2

dierence, the H2O2 concentration

configuration register

25

HPP272 User Guide M211972EN-B

More Information

‣

Vaisala Insight Software (page 28)

‣

Configuration Registers (page 48)

5.4 Modbus

The probe can be accessed using the Modbus serial communication protocol. The supported
Modbus variant is Modbus RTU (Serial Modbus) over RS-485 interface.

More Information

‣

Modbus Reference (page 45)

‣

Setting Probe in Analog or Digital Mode (page 23)

5.5

 Operation in Analog Mode

In analog output mode, the probe outputs the readings of two measurement parameters (one
parameter in each analog output channel). These measurement parameters are chosen at the
time of ordering the probe, and you can change them using Insight software and via Modbus.
You can check the chosen parameters in the calibration

The default output range for both channels is 4 ... 20 mA.

When using analog outputs, it is recommended to use a low supply voltage to minimize self­heating and maximize measurement performance. The operating voltage range with analog
output is 15 ... 25 V.

When the probe performs the chemical purge, the analog outputs have a defined behavior:

• During start-up purge, analog output is in the error state (default: 3.6 mA).

• During interval purge and manually triggered purge, output is frozen to show the last
measured value before the purge began.

certificate delivered with the probe.

More Information

‣

Setting Probe in Analog or Digital Mode (page 23)

‣

Analog Output Error State (page 40)

‣

Configuration Registers (page 48)

‣

Chemical Purge (page 11)

5.5.1 Analog Output Overrange Behavior

If the values measured by the probe are outside the scaled analog output range, the analog
output goes in the error state. The default error state is 3.6 mA.

26

Chapter 5 – Operation

More Information

‣

Analog Output Error State (page 40)

5.5.2 Triggering Purge in Analog Mode

In the analog mode, pin #5 in the probe's M12 male connector is connected to ground.
Additionally, pin #5 is used to trigger a purge in analog mode. To be able to trigger a purge, do
not connect pin #5 to ground permanently, but instead, use a relay or similar to control the pin.
For a wiring example, see Figure 8 (page 23).

1. To trigger the purge, disconnect pin #5 from ground for a minimum of 50 ms, and then
reconnect the pin to ground.

Do not leave pin #5 floating for a long time. If the probe is reset while pin #5
is floating, the probe will go into digital mode instead of analog mode.

The probe starts performing the purge. The duration of the purge is approximately 4 minutes.
During the purge, hydrogen peroxide, relative saturation, and relative humidity measurements
are not available.

27

HPP272 User Guide M211972EN-B

6. Vaisala Insight Software

Vaisala Insight software is a configuration software for Indigo-compatible probes. The
supported operating systems are Windows 7 (64-bit), Windows 8.1 (64-bit), and Windows 10
(64-bit).

With the Insight software, you can:

• See device information and status.

• See real-time measurement.
Configure serial communication settings, purge settings, filtering factor, and analog

•
output parameters and scaling.

• Calibrate and adjust the device.

Download Vaisala Insight software at www.vaisala.com/insight.

The probe can be connected to Vaisala Insight software using a Vaisala USB cable (no.

242659).

6.1

 Connecting to Insight Software

• Computer with Insight software installed

• USB connection cable (no. 242659)

Figure 10 Connecting Probe to Insight

1. Open the Vaisala Insight software.

2. Connect the USB cable to a free USB port on the PC.

3. Connect the probe to the USB cable.

4. Wait for the Insight software to recognize and identify the probe.

28

1

5

4

2

3

Chapter 7 – Using Probe with Indigo Transmitters

7. Using Probe with Indigo Transmitters

7.1 Indigo Overview

1 3.5” TFT LCD color display: non-display option with LED available for certain models.
2 Cable locking wheel: insert cable, hold in place, and turn the wheel counterclockwise.
3 Wireless configuration interface (WLAN) activation button.
4 Rubber lead-through with strain relief. Cable feedthrough option also at back of

transmitter.

5 Input/output cable.

The probe can be connected to Vaisala Indigo transmitters by using a cable.

29

HPP272 User Guide M211972EN-B

Indigo transmitters are host devices that extend the feature set of connected probes with a
range of additional options for outputs, configuration access, measurement viewing, and
status monitoring.

The selection of available additional features (for example, output and connectivity options)
varies depending on the Indigo transmitter model. Depending on the model, a display is
available as an optional selection or as a standard feature. In the non-display model, an LED
indicator is used for notifications.

7.1.1 Wireless Configuration Interface Overview

The wireless configuration interface has two user levels:

• All users have view-only access (no configuration rights, not password protected).

• Personnel that carry out configuration tasks can log in with an administrative password
that allows changing the transmitter and probe settings.

To use the wireless configuration interface to modify the settings of your Indigo transmitter
and the connected probe, you must
connect to Indigo with your mobile device or computer. Most major browsers (for example,
Firefox, Chrome, Safari, and Internet Explorer) are supported: using the most recent version is
recommended.

first enable the transmitter's wireless connection and then

30

7.2 Attaching Probes

Chapter 7 – Using Probe with Indigo Transmitters

Figure 11 Attaching Probes to Indigo

1. Connect the cable to the probe.

2. Insert the other end of the cable in Indigo's cable connector and lock it in place by turning
the locking wheel counterclockwise. Do not turn the cable connector when attaching the
cable, only the locking wheel on the transmitter.

3. When Indigo recognizes the connected probe, it shows a
display.

notification message on the

31

435

ppm

HO

74.2

%RS

RS (HO+HO)

32.4

°C

T

WLAN is activated





Indigo 201

2

1

Select WLAN to connect to:

2. Indigo_IDxx

3



HPP272 User Guide M211972EN-B

7.3 Connecting to Wireless Configuration
Interface

Figure 12 Enabling and Accessing Indigo's Wireless Configuration Interface

1 Wireless connection activation button
2 Wireless connection indicator (WLAN symbol) on the Indigo display
3 Choose Indigo (Indigo_ID[xx]) from your wireless device's list of available connections

To connect to the wireless configuration interface:

1. Press the wireless connection activation button on the bottom of the transmitter.

2. When the wireless configuration interface becomes available, the Indigo display shows a
connection notification. In the Indigo models with an LED indicator, the LED blinks green
when the connection is active.

3. Open the wireless connection menu in your mobile device or computer and select
Indigo_ID[xx] (transmitter-specific SSID) from the list of available connections.

4. Depending on your device, the wireless
automatically in your browser after you connect to Indigo, or you may need to start your
browser application manually.

5. When you open the Indigo interface in your browser, you are prompted to log in.

configuration interface either launches

Only one device can be connected to the wireless configuration interface at a
time.

32

Chapter 7 – Using Probe with Indigo Transmitters

7.4 Logging in to Wireless Configuration Interface

Figure 13 Indigo Login View

When you open Indigo's wireless configuration interface in your browser, you are prompted to
log in. There are 2 available user levels:

• User: view-only access available for all users. Does not require a password.

• Admin: password-protected access. To change settings, you must log in as admin.

To log in:

1. Enter the user name and password:

a. To log in as user (view-only access, no

User name dropdown. Leave the Password field empty.

b. To log in as admin (required for

dropdown and type the admin password (default: 12345) in the Password field.

2. Select Log in after entering the login credentials. The wireless configuration interface
opens in the Measurements view.

The user level (User or Admin) is shown in the upper right corner of all menu
views.
Select the user/admin icon in the upper right corner to change the user level.

configuration rights), select User from the

configuration), select Admin in the User name

33

HPP272 User Guide M211972EN-B

8. Maintenance

8.1 Cleaning the Probe

Do not remove the filter.CAUTION!

Do not attempt to clean the sensors under the filter in any way.CAUTION!

Avoid exposing the probe to cleaning agents for unnecessarily long periods of
time.

You can clean the H2O2 and humidity probe body and temperature probe body and cable by
wiping them with a soft, lint-free cloth moistened with water or mild cleaning agent, such as

isopropanol. Do not wipe the filter: wiping the filter may block its pores and/or deposit residue
on the filter. If the filter is heavily contaminated, replace it.

When cleaning, follow these precautions:

• Avoid touching the filter. If you need to touch the filter, always wear clean gloves (cotton,
rubber, or similar material). Keep the

• Do not scrape the probe body.

• Do not immerse the probe in liquid to clean it.

• Wipe cleaning agents

If needed, you can spray the probe surfaces with water.

After cleaning the probe, it is recommended to perform a chemical purge.

o the probe after cleaning.

filter free of any grease or oil.

8.1.1 Chemical Tolerance

Avoid exposing the probe to chemicals for unnecessarily long periods of time. Do
not immerse the probe in a chemical, and wipe chemicals o the probe after
exposure.

You can use mild cleaning agents, such as isopropanol, to wipe the probe body. Avoid
exposing the

The probe does not withstand DMSO (dimethyl sulfoxide C2H6OS).

After exposing the probe to chemicals, it is recommended to perform a chemical purge.

34

filter to chemicals.

Chapter 8 – Maintenance

More Information

‣

Chemical Purge (page 11)

‣

Triggering Purge in Analog Mode (page 27)

8.2 Calibration and Adjustment

The probe is fully calibrated and adjusted as shipped from the factory. A typical calibration
interval is 1 year, depending on how frequently and long your probe is exposed to vaporized
H2O2.

Calibration and adjustment is performed by Vaisala. For contact information, visit

www.vaisala.com/calibration.

35

HPP272 User Guide M211972EN-B

9. Troubleshooting

9.1 Problems and Their Possible Solutions

If you have a problem with using the probe, check the following tables before contacting
Vaisala. If the problem you have is not listed in the tables, or if the proposed solution does not
fix the problem, contact Vaisala technical support.

You can check the probe diagnostics and status with the Insight software and Modbus status
registers (see Status Registers (page 54)).

Problem: Response time is slower than specified.

Possible Cause: Solution:

The filter is blocked. Change the filter.

Be careful not to touch the sensors when the filter is o the
probe.

The probe has fallen and the
filter has hit the floor.

The probe has been exposed to
unsuitable chemicals (for
example, DMSO).

The measurement filtering
factor is configured to be too
slow.

The ambient temperature has
changed quickly, which may
result in a slower change in RH
reading.

Remove the filter and visually check the sensors.

• If the sensors are bent, broken, or disconnected, contact
Vaisala technical support.

• If the sensors are intact, change the filter. The filter is made of
porous material, and if the filter hits the floor, the filter material
may get pressed and become less permeable. This reduces the
rate at which air
the measurement.

Be careful not to touch the sensors when the
probe.

Change the filter and perform a chemical purge.

Be careful not to touch the sensors when the filter is o the
probe.

Use the Vaisala Insight software, Modbus configuration register
030A

, or an Indigo 200 transmitter to disable the filtering

hex

factor (set filtering factor to "1"), and check the measurement
again. See:

• Measurement Filtering Factor (page 12)

• Vaisala Insight Software (page 28)

•

Configuration Registers (page 48)

No actions required.

flows in and out of the filter, directly aecting

filter is o the

36

Chapter 9 – Troubleshooting

Problem: H2O2 or humidity reading does not change during regular use for less than 5 minutes.

Possible Cause: Solution:

Purge is being performed

No actions required.
(duration of the purge is 4
minutes).

Problem: H2O2 or humidity reading does not change during regular use for more than 5 minutes.

Possible Cause: Solution:

In analog mode: The scaling of
the output is unsuitable,

Check and change the analog output scaling with Insight

software (see Vaisala Insight Software (page 28)).
preventing the change from
showing.

In analog mode: The error level
is configured within the
measurement output level, and
the probe is in error state.

Problem: Measurement reading appears incorrect.

Check the probe diagnostics with the Insight software (see

Vaisala Insight Software (page 28)).

Consider changing the analog output error level to be outside the

measurement scale.

Possible Cause: Solution:

The temperature probe is
installed near a heat source or

Change the location of temperature probe. See Installation

(page 20) for recommended installation locations.

too close to the H2O2 and
humidity probe.

The filter is wet. Remove the filter, pour out any water, and let the filter dry.

Depending on air humidity and temperature, drying the filter in

ambient air can take from a few hours to a day. Alternatively, you

can dry the removed filter with nitrogen gas or dry pressurized

air. When the filter is dry, reinstall the filter.

Be careful not to touch the sensors when the filter is o the

probe.

Perform a chemical purge.

The filter is blocked or dirty. Change the filter.

Be careful not to touch the sensors when the filter is o the

probe.

Condensation has formed on
the sensor when the probe was
powered o.

When the probe is powered o, exposure to H2O2 condensation

can break the PEROXCAP sensor within a day, and the sensor will

not recover. When the probe is powered on, the heated sensor

withstands condensing H2O2 conditions.

A sensor damaged with H2O2 condensation during power-o

time cannot be repaired.

37

HPP272 User Guide M211972EN-B

Problem: Measurement reading appears incorrect.

The filter is not installed on the
probe.

The yellow transport cap is still
on the probe.

Do not use the probe without the filter. Install the filter on the
probe.

Remove the yellow transport cap when measuring with the
probe.

The filter is broken. Do not use the probe if the filter is broken. Remove the filter and

visually check the sensors:

• If the sensors are bent, broken, or disconnected, contact
Vaisala technical support.

• If the sensors are intact, change the filter.

Be careful not to touch the sensors when the filter is o the
probe.

In analog mode: Maximum load
has been exceeded.

Check the analog output load, and reduce it to the specified
maximum load or less. See Table 6 (page 42) for the permitted
maximum load.

Ambient pressure is not normal
atmospheric pressure.

Problem: The filter is wet.

Check the ambient pressure. See Table 8 (page 43) for the
permitted operating pressure.

Possible Cause: Solution:

Sprayed water has entered the
filter when cleaning the probe.

Remove the filter, pour out any water, and let the filter dry.
Depending on air humidity and temperature, drying the filter in
ambient air can take from a few hours to a day. Alternatively, you
can dry the removed filter with nitrogen gas or dry pressurized
air. When the filter is dry, reinstall the filter.

Be careful not to touch the sensors when the filter is o the
probe.

Perform a chemical purge.

Problem: The filter is broken.

Possible Cause: Solution:

The probe has fallen or an
object has hit the filter.

Do not use the probe if the filter is broken. Remove the filter and
visually check the sensors:

• If the sensors are bent, broken, or disconnected, contact
Vaisala technical support.

• If the sensors are intact, change the filter.

Be careful not to touch the sensors when the filter is o the
probe.

38

Chapter 9 – Troubleshooting

Problem: H2O2 concentration reading shows > 0 ppm even though the probe is not exposed to H2O2.

Possible Cause: Solution:

Normal variation due to a slight

No actions required.
dierence in behavior between
the two humidity sensors.

If the reading remains > 0 ppm
for 2 ... 10 hours, H2O

2

concentration has drifted.

The intelligent measurement algorithm can correct errors of

< 30 ppm by itself when the probe is not exposed to H2O2. Keep

the probe powered on for a few hours in a stable temperature

and RH, not exposed to H2O2.

Problem: The probe does not power on, or there is no communication from the probe after power-on.

Possible Cause: Solution:

Power input to the probe is o. Turn on the power input to the probe.

Probe wiring is incorrect. Check the probe wiring and correct it if needed. See Wiring

(page 22).

The probe cable is not properly

Check the cable connection and correct it if needed.
connected.

The operating voltage is
incorrect.

In digital mode: The
communication settings (for
example the device address)
are incorrect either in the probe

Check the operating voltage and correct if needed. See Table 6

(page 42) for the correct voltage.

Check the communication settings. You can check the probe's

communication settings with the Insight software. See

• Vaisala Insight Software (page 28)

or in the system where the
probe is connected.

Problem: In analog mode, there is no output signal (signal level is 0 mA).

Possible Cause: Solution:

Pin #5 was floating at start-up

Check pin #5. See Wiring (page 22).
or reset, which means the
probe is in digital mode.

Analog outputs are configured
to be o.

Check the analog output mode with the Insight software or

Modbus configuration registers 0700

and 0800

hex

hex

. See:

• Vaisala Insight Software (page 28)

• Configuration Registers (page 48)

Probe wiring is incorrect. Check the probe wiring and correct it if needed. See Wiring

(page 22).

The operating voltage is
incorrect.

Check the operating voltage and correct if needed. See Table 6

(page 42) for the correct voltage.

39

HPP272 User Guide M211972EN-B

Problem: In analog mode, there is no output signal (signal level is 0 mA).

The probe cable is not properly
connected.

Power input to the probe is o. Turn on the power input.

The analog output error level is
configured to be 0 mA, and the
probe is performing start-up
purge or is in error state.

Problem: At start-up in analog mode, the probe remains in the error state for over 5 minutes.

Possible Cause: Solution:

The analog output scaling is
unsuitable. For example, the
scale 0 ... 5 %RH is too narrow
compared to the full
measurement scale of RH.

There is a probe or sensor error. Check the probe diagnostics with the Insight software (see

Problem: In analog mode, start-up purge is not performed.

Possible Cause: Solution:

The probe is in digital mode at
start-up (pin #5 is floating).

Check the cable connection and correct it if needed.

Wait for 5 minutes for the possible start-up purge to finish. If the
output remains 0 mA after 5 minutes, check the probe
diagnostics with the Insight software (see Vaisala Insight

Software (page 28)).

Check the analog output scaling with the Insight software and
correct the scaling if needed (see Vaisala Insight Software

(page 28)).

Vaisala Insight Software (page 28)).

Check pin #5. See Wiring (page 22).

9.2 Analog Output Error State

The probe sets the analog output channel into a defined error level instead of the measured
result in three situations:

• Probe is performing start-up purge (duration 4 minutes).

• Probe detects a measurement malfunction. This means an actual measurement problem,
such as sensor damage, or unsuitable environmental conditions.

• Measured value(s) are outside the scaled output range.

The default error level for the analog outputs is 3.6 mA. You can change the error level (range
0 ... 25 mA) with the Insight software and via Modbus (registers 0706

More Information

‣

Configuration Registers (page 48)

40

and 0806

hex

hex

).

Chapter 10 – Technical Data

10. Technical Data

Table 5 Measurement Performance

Property Description/Value

Hydrogen Peroxide

Sensor PEROXCAPâ

Measurement range 0 ... 2000 ppm

Measurement temperature range +5 ... +50 °C (+41 ... +122 °F)

Repeatability at +25 °C (+77 °F), 500 ppm H2O

2

Accuracy (including non-linearity, hysteresis, and
repeatability) at +25 °C (77 °F), 10 ... 2000 ppm H2O

Factory calibration uncertainty, at +25 °C (+77 °F), 500
ppm H2O2

1)

Response time at +23 °C (+73 °F), still air:

T

63

T

90

Relative Saturation

Measurement range 0 ... 100 %RS

Measurement temperature range +5 ... +50 °C (+41 ... +122 °F)

Repeatability at +25 °C (+77 °F), 500 ppm H2O

2

Accuracy (including non-linearity, hysteresis, and repeatability) at +25 °C (+77 °F):

at 0 ppm H2O

at 500 ppm H2O

Factory calibration uncertainty, at +25 °C (+77 °F), 500
ppm H2O2

2

2

1)

Relative Humidity

Measurement range 0 ... 100 %RH

Measurement temperature range +5 ... +70 °C (+41 ... +158 °F)

Accuracy (including non-linearity, hysteresis, and repeatability):

at 0 ppm H2O2, 0 ... 60 %RH, +25 °C (77 °F) ±1 %RH

at 0 ppm H2O2, 0 ... 95 %RH, over temperature range ±2 %RH

at 500 ppm H2O2, 0 ... 95 %RH, +25 °C (77 °F) ±2 %RH

±20 ppm

±10 ppm or 5 % of reading (whichever
is greater)

2

±10 ppm

120 s

200 s

±0.5 %RS

±2 %RS

±6 %RS

±2 %RS

41

HPP272 User Guide M211972EN-B

Property Description/Value

Factory calibration uncertainty, at +25 °C (77 °F), 0 ppm H2O2:

1)

at 0 … 40 %RH ±0.6 %RH

at 40 … 95 %RH ±1 %RH

Temperature

Sensor Pt-1000 RTD Class F0.1

Accuracy over temperature range ±0.2 °C (±0.36 °F)

Other Parameters

Absolute H2O2, absolute H2O, H2O ppm by volume, saturation vapor pressure

1) Defined as ±2 standard deviation limits. See also calibration certificate.

Table 6 Inputs and Outputs

Property Description/Value

Operating voltage With digital output: 15 ... 30 VDC

With analog output: 15 ... 25 VDC (use lowest available
operating voltage to minimize heating)

Current Consumption at +25 °C (+77 °F)

In digital mode Max. 15 mA

In analog mode Max. 50 mA

During purge Max. 200 mA

Digital Output

Interface RS-485, not isolated, no line termination

Bit rate 9600, 19200 (default), 38400, 57600, or 115200 bps

Parity None (default), even, odd

Data bits 8

Stop bits 1, 2 (default)

Communication protocol Modbus RTU v.1.02

Analog Output

Outputs 2 × 4 ... 20 mA 3-wire current outputs

Max. load 500 Ω

42

118.3

44

Ø=18.5

69.8, Ø=4.8

38.5

Ø=30

400

22

Ø=16/18.5

mm

Chapter 10 – Technical Data

Table 7 Mechanical Specifications

Property Description/Value

Weight 130 g

IP rating IP65

Connector M12/5 male

Materials

Probe body AISI316L stainless steel

Filter cap Porous PTFE

Temperature probe AISI316L stainless steel

Temperature probe cable PTFE

Table 8 Operating Environment

Property Description/Value

Operating temperature +0 ... +70 °C (+32 ... +158 °F)

Storage temperature -20 ... +70 °C (-4 ... +158 °F)

Ambient pressure Normal atmospheric pressure

EMC compliance EN61326-1, Controlled Environment

10.1 Dimensions

Figure 14 HPP272 Dimensions

43

HPP272 User Guide M211972EN-B

10.2 Accessories

Table 9 Spare Parts and Accessories

Name Order Code

USB cable for PC connection 242659

Probe cable with open wires (1.5 m) 223263SP

Probe cable with open wires (3 m) 26719SP

Probe cable with open wires (5 m) 26720SP

Probe cable with open wires (10 m) 216546SP

Probe cable with open wires and 90° plug (0.6 m) 244669SP

Filter DRW246363SP

Gland set for through-wall installation, HPP272 HPP272MOUNTINGSET1

Transmitters

Indigo 200 series See www.vaisala.com/indigo

Connection cable to Indigo (1 m) INDIGOCABLE1M

Connection cable to Indigo (3 m) INDIGOCABLE3M

Connection cable to Indigo (5 m) INDIGOCABLE5M

Connection cable to Indigo (10 m) INDIGOCABLE10M

44

Appendix A – Modbus Reference

Appendix A. Modbus Reference

A.1 Default Communication Settings

Table 10 Default Modbus Serial Communication Settings

Description Default Value

Serial bit rate 19200

Parity N

Number of data bits 8

Number of stop bits 2

Modbus device address 240

A.2 Function Codes

Table 11 Modbus Function Codes

Function Code
(Decimal)

03 03

16 10

43 / 14 2B

Function Code
(Hexadecimal)

hex

hex

/ 0E

hex

hex

Name Notes

Read Holding
Registers

Write Multiple
Registers

Read Device

Identification

Class 0

Class 0

A.3 Data Encoding

In the data registers, the numeric values are available in one or two formats with separate
register addresses: 32-bit IEEE

A.3.1 32-Bit Floating Point or Integer Format

Least-significant 16 bits of floating point or integer numbers are placed at the smaller Modbus
address as specified in Open Modbus TCP Specification, Release 1.0. This is also known as
"little-endian" or "Modicon" word order. Floating point values are represented in standard IEEE

floating point format.

32-bit

floating point format and/or 16-bit signed integer format.

45

HPP272 User Guide M211972EN-B

Despite the specification, some Modbus masters may expect "big-endian" word
order (most-significant word first). In such case, you must select "word-swapped"
floating point format in your Modbus master for the Modbus registers of the
device.

A "quiet NaN" value is returned for unavailable values. A quiet NaN is, for example,
7FC00000

; however, the master should understand any NaN value.

hex

A complete 32-bit floating point or integer value should be read and written in a
single Modbus transaction.

A.3.2 16-Bit Integer Format

Some 16-bit integer values in the data registers are scaled to include the necessary decimals.
The scaling factors for those values are shown in the register tables.

Table 12 16-bit Signed Integer Format Details

Value Description

0000

8002

8000

hex

hex

hex

… 7FFE

… FFFF

hex

hex

Value in range 0 … 32766

Value in range -32766 … -1 (2’s complement)

Value is not available (quiet NaN)

Some values may exceed the signed 16-bit range even in normal operation. To
access such values, use the floating point registers instead.

A.4 Modbus Registers

CAUTION!

1-based (the register addresses start from 1). Note that the register addresses in
actual Modbus messages (Modbus Protocol Data Unit (PDU)) start from zero.
Subtract 1 from the decimal addresses presented in this manual to get the
address used in the Modbus message (for example, the decimal register address
1 becomes register address 0 in the actual Modbus message).

Accessing unavailable (temporarily missing) measurement data does not generate an
exception. “Unavailable” value (a quiet NaN for

data) is returned instead. An exception is generated only for any access outside the applicable
register ranges.

46

The decimal numbering of register addresses used in this manual is

floating point data or 0000

for integer

hex

A.4.1 Measurement Data Registers

Table 13 Modbus Measurement Data Registers (Read-Only)

Appendix A – Modbus Reference

Address
(Decimal)

Address
(Hexadecimal)

1 0000

3 0002

5 0004

7 0006

9 0008

15 000E

17 0010

19 0012

21 0014

23 0016

257 0100

258 0101

259 0102

hex

hex

hex

hex

hex

hex

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Vaporized hydrogen peroxide

Format

32-bit float ppm

Unit

concentration by volume

H2O+H2O2 relative saturation 32-bit float %RS

Temperature used for calculation. By

32-bit float °C
default, shows the temperature from
the temperature probe (register
0016

).

hex

If temperature compensation is turned
ON (register 0505

), this register

hex

shows the volatile value for given
temperature reading (register 0302

hex

).

See Table 14 (page 49).

Relative humidity 32-bit float %RH

Absolute hydrogen peroxide 32-bit float

mg/m

Water concentration by volume 32-bit float ppm

Water vapor pressure 32-bit float hPa

Absolute humidity (water) 32-bit float

g/m

Water vapor saturation pressure 32-bit float hPa

Temperature from the temperature

32-bit float °C
probe

Vaporized hydrogen peroxide
concentration by volume

16-bit

signed

ppm

integer

H2O+H2O2 relative saturation 16-bit

%RS * 100
signed
integer

Temperature used for calculation. By
default, shows the temperature from
the temperature probe (register
010B

).

hex

16-bit
signed
integer

°C * 100

If temperature compensation is turned
ON (register 0505

), this register

hex

shows the volatile value for given
temperature reading (register 0302

hex

).

See Table 14 (page 49).

3

3

47

HPP272 User Guide M211972EN-B

Address
(Decimal)

260 0103

261 0104

264 0107

265 0108

266 0109

267 010A

268 010B

Address
(Hexadecimal)

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Relative humidity 16-bit

Absolute hydrogen peroxide 16-bit

Water concentration by volume 16-bit

Water vapor pressure 16-bit

Absolute humidity (water) 16-bit

Water vapor saturation pressure 16-bit

Temperature from the temperature
probe

A.4.2 Configuration Registers

Format

signed
integer

signed
integer

signed
integer

signed
integer

signed
integer

signed
integer

16-bit
signed
integer

Unit

%RH *100

3

mg/m

ppm

hPa

3

g/m

hPa

°C * 100

48

CAUTION!

Default power-up values (registers 773 ... 775) are written into non­volatile EEPROM memory. The EEPROM memory implementation has a limit of
30000 writes, and is intended to be used only when saving long-term or
permanent configurations. Use the volatile memory (registers 769 ... 771, values
cleared on power-up) for non-permanent configurations (for example, if the
probe is used in a system that regularly updates the given values).

Table 14 Modbus Configuration Data Registers (Writable)

Appendix A – Modbus Reference

Address
(Decimal)

Address
(Hexadecimal)

769 0300

771 0302

773 0304

775 0306

777 0308

hex

hex

hex

hex

hex

Register Description Data

Volatile value for

Format

32-bit float hPa
pressure compensation
(value cleared at probe
reset). Used for
compensating the
measurement for
pressure if pressure
compensation is turned
ON (register 0504

Volatile value for given

hex

).

32-bit float °C
temperature reading
(value cleared at probe
reset). Used for
calculations instead of
the temperature from the
temperature probe if
temperature
compensation is turned
ON (register 0505

Power-up value for

hex

).

32-bit float hPa
pressure compensation

Power-up value for given

32-bit float °C
temperature reading

Purge interval 16-bit

integer

Unit / Valid Range

813.25 ... 1213.25

(default 1013.25 hPa)

(Init copied from power­up value)

-40 ... +80

(Init copied from power­up value)

813.25 ... 1213.25

(default 1013.25 hPa)

-40 ... +80

min

60 ... 10080

(= 1 hour ... 1 week)

(default: 1440 (= 24
hours))

49

HPP272 User Guide M211972EN-B

Address
(Decimal)

Address
(Hexadecimal)

779 030A

781 030C

1283 0502

1285 0504

hex

hex

hex

hex

Register Description Data

Measurement filtering

Format

32-bit float Range: 0.01 ... 1
factor (does not aect
temperature, water, or RH
measurement)

Unit / Valid Range

1 = Filter is disabled

< 1 = Reading is a
combination of latest
measurement and the
earlier reading. The value
of the register defines the
portion of the latest
measurement, for
example, 0.9 means the
reading consists 90 % of
the latest measurement
and 10 % of the earlier
reading.

Low H2O2 clipping limit 32-bit float ppm

Any numerical value

(default: 0)

Purge status / manual
start

16-bit

function

status

When reading from
register:

1 ... 100 = Purge is in
progress (progress
shown as 1 ... 100%)

0 = Previous purge
completed successfully,
purge is not in progress

... -1 = Previous purge has
failed

When writing to register:

1 = Start purge

Pressure compensation

on/o

16-bit

boolean

1 = On

0 = O

50

Appendix A – Modbus Reference

Address
(Decimal)

Address
(Hexadecimal)

1286 0505

1287 0506

1537 0600

1538 0601

1539 0602

1540 0603

1541 0604

Analog Output 1:

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Temperature
compensation on/o

Format

16-bit
boolean

Unit / Valid Range

0 = O

1 = On. If turned on,
overrides the
temperature from the
temperature probe in the
calculation of other
measurement
parameters. Define the
temperature in registers
0302

hex

and 0306
value).

(default: 0 = O)

Manual purge trigger in
analog mode on/o

16-bit
boolean

1 = On

0 = O

(default: 1 = On)

Modbus address 16-bit

1 ... 255 (default: 240)

integer

Bit rate enum 5 = 9600

6 = 19200

7 = 38400

8 = 57600

9 = 115200

(default: 6 = 19200)

Parity, number of data
bits, number of stop bits

enum 0 = None, 8, 1

1 = None, 8, 2

2 = Even, 8, 1

3 = Even, 8, 2

4 = Odd, 8, 1

5 = Odd, 8, 2

(default: 1 = None, 8, 2)

Response delay 16-bit

integer

Restart device 16-bit

function
status

ms

0 ... 1000

When writing to register:

1 = Restart the device

(volatile value)

(power-up

hex

51

HPP272 User Guide M211972EN-B

Address
(Decimal)

Address
(Hexadecimal)

1793 0700

1794 0701

1795 0702

1797 0704

1799 0706

Analog Output 2:

2049 0800

2050 0801

2051 0802

hex

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Format

Unit / Valid Range

Output mode enum 0 = O

1 = 0 ... 20 mA

2 = 4 ... 20 mA

(default: 2 = 4 ... 20 mA)

Output parameter 16-bit

register

address

Valid range
0000

... 0016

hex

For the available

hex

.

parameters and their
register addresses, see

Table 13 (page 47).

Scale low end 32-bit float Set the lower limit of the

measurement scale for
the output parameter
chosen in register 0701

(Output parameter).

Scale high end 32-bit float Set the upper limit of the

measurement scale for
the output parameter
chosen in register 0701

(Output parameter).

Error output 32-bit float mA

0 ... 25

Output mode enum 0 = O

1 = 0 ... 20 mA

2 = 4 ... 20 mA

(default: 2 = 4 ... 20 mA)

Output parameter 16-bit

register

address

Valid range
0000

... 0016

hex

For the available

hex

.

parameters and their
register addresses, see

Table 13 (page 47).

Scale low end 32-bit float Set the lower limit of the

measurement scale for
the output parameter
chosen in register 0801

(Output parameter).

hex

hex

hex

52

Appendix A – Modbus Reference

Address
(Decimal)

Address
(Hexadecimal)

2053 0804

2055 0806

Service Agreement:

2817 0B00

2829 0B0C

2841 0B18

2844 0B1B

Factory Settings:

7937 1E00

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Format

Unit / Valid Range

Scale high end 32-bit float Set the upper limit of the

measurement scale for
the output parameter
chosen in register 0801

(Output parameter).

Error output 32-bit float mA

0 ... 25

Customer name 24-

Read-only
character
ASCII string

Contract number 24-

Read-only
character
ASCII string

Start date three 16-bit

Read-only
integer
decimal
values
(YYYY, M,
and D)

End date three 16-bit

Read-only
integer
decimal
values
(YYYY, M,
and D)

Restore factory settings 16-bit

function
status

When writing to register:

1 = Restore factory

settings (cancel all

changes made by the

user)

hex

53

HPP272 User Guide M211972EN-B

A.4.3 Status Registers

Table 15 Modbus Status Registers (Read-Only)

Address
(Decimal)

Address
(Hexadecimal)

513 0200

514 0201

516 0203

hex

hex

hex

Register Description Data

Format

Notes

Device status 16-bit 0 = Status OK.

1 = Critical error,
maintenance needed.

2 = Error, device may
recover automatically.

4 = Warning.

8 = Notification.

1)

Status code low 32-bit See Table 16 (page 55) .

Status code high 32-bit See Table 17 (page 56) .

1)

1)

54

Appendix A – Modbus Reference

Address
(Decimal)

529 0210

530 0211

531 0212

532 0213

533 0214

536 0217

537 0218

538 0219

539 021A

540 021B

Address
(Hexadecimal)

hex

hex

hex

hex

hex

hex

hex

hex

hex

hex

Register Description Data

Status of Hydrogen

Format

16-bit 0 = Status OK.

peroxide concentration
by volume

Status of H2O+H2O

16-bit

2

relative saturation

Status of Temperature 16-bit

Status of Relative

16-bit

humidity

Status of Absolute

16-bit

hydrogen peroxide

Status of Water

16-bit

concentration by volume

Status of Water vapor

16-bit

pressure

Status of Absolute

16-bit

humidity

Status of Water vapor

16-bit

saturation pressure

Status of Temperature

16-bit

from the temperature

Notes

2 = Reading is not

reliable.

32 = Reading is locked

during purge.

128 = Sensor failure.

256 = Measurement not

ready

1)

probe

1) Multiple statuses can be present simultaneously. In those cases, the value of the status
register is the sum of the status values. For example the value of the device status register is
6 if a warning (4) and an error (2) are present simultaneously.

Table 16 Error Codes in Register 0201

Value of
Register
0201

hex

Error Message Severity

(32-bit)

hex

0 Status OK.

1 Firmware checksum mismatch. Critical

2 Device settings corrupted. Critical

8 Supply voltage too high. Error

16 Internal voltage too low. Error

32 Internal voltage too high. Error

64 Humidity sensor failure (open circuit). Error

55

HPP272 User Guide M211972EN-B

Value of
Register
0201

hex

Error Message Severity

1024 Humidity sensor failure (open circuit). Error

16384 Temperature sensor failure (open circuit). Error

32768 Temperature sensor failure (short circuit). Error

262144 Temperature sensor failure (open circuit). Error

524288 Temperature sensor failure (short circuit). Error

4194304 Temperature sensor failure (open circuit). Error

8388608 Temperature sensor failure (short circuit). Error

Table 17 Error Codes in Register 0203

Value of
Register
0203

hex

Error Message Severity

(32-bit)

hex

0 Status OK.

256 A/D converter failure (external). Error

512 Non-volatile memory read/write failure. Error

4096 Humidity sensor failure (short circuit). Error

8192 Purge in progress. Info

16384 A/D converter failure (internal). Error

32768 Calibration is about to expire. Info

65536 Calibration has expired. Warning

A.4.4 Device Identification Objects

Table 18 Device Identification Objects

Object Id
(decimal)

0 00

1 01

2 02

3 03

56

Object Id
(hexadecimal)

hex

hex

hex

hex

Object Name Example Contents

VendorName “Vaisala”

ProductCode HPP272

MajorMinorVersion Software version (for example “1.2.3”)

VendorUrl “http://www.vaisala.com/”

Appendix A – Modbus Reference

Object Id
(decimal)

4 04

128 80

129 81

130 82

Object Id
(hexadecimal)

hex

hex

hex

hex

A.4.5 Test Value Registers

Table 19 Test Value Registers

Address
(Decimal)

7937 1F00

7938 1F01

7940 1F03

Address
(Hexadecimal)

hex

hex

hex

Object Name Example Contents

ProductName Hydroxen Peroxide, Humidity, and

Temperature Probe HPP272

SerialNumber Serial number of the device (for

example “K0710040”)

Calibration date Date of the factory calibration

Calibration text Information text of the factory

calibration

Register
Description

Data Format Value

Signed integer 16-bit integer -12345

Floating point 32-bit float -123.45

Text string 8-character ASCII

"-123.45"

string

57

HPP272 User Guide M211972EN-B

A.5 Modbus Communication Examples

Reading H2O2 Concentration Value

Device address used in the following examples is 240 (F0

hex

).

The values returned by the device dier depending on the ambient conditions
and/or device settings. Your device might not return exactly same values.

Request Response

Bytes on the Line
(Hexadecimal)

(silence for 3.5 bytes) Start of Modbus RTU

F0

hex

03

hex

00

hex

00

hex

00

hex

02

hex

D1

hex

2A

hex

(silence for 3.5 bytes) End of Modbus RTU

Description Bytes on the Line

(Hexadecimal)

(silence for 3.5 bytes) Start of Modbus RTU

frame

HPP272 address F0

Function (Read
Holding Registers)

Register address 04

Number of 16-bit
registers to read (2)

Modbus RTU
checksum

frame

03

D4

7A

43

E8

33

AB

hex

hex

hex

hex

hex

hex

hex

hex

hex

Description

frame

HPP272 address

Function (Read
Holding Registers)

Number of data bytes

Value of first register
(least significant
word)

Value of second
register (most
significant word)

Modbus RTU
checksum

(silence for 3.5 bytes) End of Modbus RTU

frame

Communication Description

Register address 1 (1-based Modbus documentation format) =

0000

(0-based format used in actual

hex

communication).

Data format Two 16-bit Modbus registers interpreted as IEEE

754 binary32 floating point value, least
significant word first.

Returned value 43E8D47A

, which is binary32 representation

hex

of 465.65997 (ppm).

58

Writing Purge Interval Value

Request Response

Bytes on the Line
(Hexadecimal)

(silence for 3.5 bytes) Start of Modbus RTU

F0

hex

10

hex

03

hex

08

hex

00

hex

01

hex

02

hex

0B

hex

40

hex

9B

hex

4C

hex

(silence for 3.5 bytes) End of Modbus RTU

Description Bytes on the Line

(Hexadecimal)

(silence for 3.5 bytes) Start of Modbus RTU

frame

HPP272 address F0

Function (Write
Multiple Registers)

Register address 03

Number of registers to
write (1)

Number of data bytes 95

Value for the register 6E

10

08

00

01

hex

hex

hex

hex

hex

hex

hex

hex

(silence for 3.5 bytes) End of Modbus RTU

Modbus RTU
checksum

frame

Appendix A – Modbus Reference

Description

frame

HPP272 address

Function (Write
Multiple Registers)

Register address

Number of 16-bit
registers written (1)

Modbus RTU
checksum

frame

The response to a write
function informs that the
function was correctly received
by the device. It does not
guarantee that the written
value was accepted by the
device (for example, in case
out-of-range values).

To verify that the value was
really accepted by the device,
read the register value after
writing.

Communication Description

Register address 777 (1-based Modbus documentation format) =

0308

(0-based format used in actual

hex

communication).

Data format One 16-bit Modbus register interpreted as 16-bit

integer value.

59

HPP272 User Guide M211972EN-B

Communication Description

Value to write 0B40

= 2880 (minutes) (= 48 hours)

hex

60

Warranty

For standard warranty terms and conditions, see www.vaisala.com/warranty.
Please observe that any such warranty may not be valid in case of damage due to normal wear
and tear, exceptional operating conditions, negligent handling or installation, or unauthorized
modifications. Please see the applicable supply contract or Conditions of Sale for details of the
warranty for each product.

Technical Support

Contact Vaisala technical support at [e-mail]. Provide at least the
following supporting information:

• Product name, model, and serial number

• Name and location of the installation site

• Name and contact information of a technical person who can provide further
information on the problem

For more information, see www.vaisala.com/support.

Recycling

Recycle all applicable material.

Follow the statutory regulations for disposing of the product and packaging.

61

HPP272 User Guide M211972EN-B

62

www.vaisala.com