IEC 61987-1:2024

IEC 61987-1 ®
Edition 2.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial- process measurement and control – Data structures and elements in
process equipment catalogues –
Part 1: Generic structures for measuring equipment

Mesure et commande dans les processus industriels – Eléments et structures de
données dans les catalogues d'équipements de processus –
Partie 1: Structures génériques pour équipements de mesure
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IEC 61987-1 ®
Edition 2.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Industrial- process measurement and control – Data structures and elements in

process equipment catalogues –

Part 1: Generic structures for measuring equipment

Mesure et commande dans les processus industriels – Eléments et structures

de données dans les catalogues d'équipements de processus –

Partie 1: Structures génériques pour équipements de mesure

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40, 35.240.50 ISBN 978-2-8322-9817-6

– 2 – IEC 61987-1:2024 © IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
4 Metadocuments . 18
4.1 General . 18
4.2 Metadocument clauses and features . 20
4.2.1 General . 20
4.2.2 Composite measuring equipment . 21
4.2.3 Measuring equipment with a digital communication interface . 22
4.3 Nomenclature . 22
5 Metadocument for process measuring equipment . 22
5.1 Identification . 22
5.1.1 General . 22
5.1.2 Document identification . 22
5.1.3 Date of issue . 22
5.1.4 Product type . 22
5.1.5 Product name . 22
5.1.6 Version . 22
5.1.7 Manufacturer . 23
5.2 Application . 23
5.3 Function and system design . 23
5.3.1 General . 23
5.3.2 Measuring principle . 23
5.3.3 Equipment architecture . 23
5.3.4 Communication and data processing . 23
5.3.5 Dependability . 23
5.4 Input . 24
5.4.1 General . 24
5.4.2 Measured variable . 24
5.4.3 Measuring range . 24
5.5 Output. 24
5.5.1 General . 24
5.5.2 Output signal . 24
5.5.3 Signal on alarm . 25
5.5.4 Load . 25
5.6 Digital Communication . 25
5.6.1 General . 25
5.6.2 Communication protocol . 25
5.6.3 Communication variable . 25
5.6.4 Physical layer . 25
5.7 Performance characteristics . 26
5.7.1 General . 26
5.7.2 Accuracy . 26
5.7.3 Measured error . 26

5.7.4 Hysteresis . 26
5.7.5 Non-repeatability . 26
5.7.6 Start-up drift . 26
5.7.7 Long-term drift . 26
5.7.8 Influence of ambient temperature . 26
5.7.9 Influence of medium temperature . 27
5.7.10 Settling time . 27
5.8 Operating conditions . 27
5.8.1 General . 27
5.8.2 Installation . 27
5.8.3 Environment . 28
5.8.4 Process . 29
5.9 Mechanical and electrical construction . 29
5.9.1 General . 29
5.9.2 Design . 29
5.9.3 Dimensions . 30
5.9.4 Weight . 30
5.9.5 Material . 30
5.9.6 Electrical connection . 30
5.9.7 Degree of protection . 30
5.9.8 Type of protection . 30
5.9.9 Process connection . 30
5.10 Operability . 30
5.11 Power supply . 31
5.12 Certificates and approvals. 31
5.13 Ordering information . 31
5.14 Documentation . 31
Annex A (normative) Classification of features as a function of measuring equipment . 32
Annex B (informative) Classification of features as a function of measurement
principle . 35
B.1 Additional features proposed for flow measurement principles . 35
B.1.1 Overview . 35
B.1.2 Output . 38
B.1.3 Performance characteristics . 38
B.1.4 Installation . 39
B.1.5 Process . 39
B.1.6 Mechanical construction – Field coil isolation class. 40
B.2 Additional features proposed for level measurement principles . 40
B.2.1 Overview . 40
B.2.2 Input . 43
B.2.3 Output – Signal resolution . 43
B.2.4 Performance characteristics – Influence of medium pressure . 43
B.2.5 Installation – Emitting angle . 43
B.2.6 Process . 43
B.3 Additional features proposed for pressure measurement principles . 44
B.3.1 Overview . 44
B.3.2 Function and system design – Measurement type . 47
B.3.3 Input . 47
B.3.4 Output . 48

– 4 – IEC 61987-1:2024 © IEC 2024
B.3.5 Performance characteristics . 49
B.3.6 Operating conditions/process. 49
B.3.7 Mechanical and electrical construction . 50
B.4 Additional features proposed for temperature measurement principles . 50
B.4.1 Overview . 50
B.4.2 Input . 53
B.4.3 Output – Linearization . 53
B.4.4 Performance characteristics . 54
B.5 Additional features proposed for density measurement principles . 54
B.5.1 Overview . 54
B.5.2 Performance characteristics – Influence of medium pressure . 57
B.5.3 Installation conditions – Cable length . 57
B.5.4 Process conditions . 57
Bibliography . 58

Figure 1 – Classification scheme for process measuring equipment (letter codes D, F,
L etc. identifying the measuring equipment function taken from ISO 3511-1) . 20

Table A.1 – Classification and documentation structure of measuring equipment . 32
Table B.1 – Classification and documentation structure of flow measuring equipment . 35
Table B.2 – Classification and documentation structure of level measuring equipment . 40
Table B.3 – Classification and documentation structure of pressure measuring
equipment . 44
Table B.4 – Classification and documentation structure of temperature measuring
equipment . 51
Table B.5 – Classification and documentation structure of density measuring
equipment . 54

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
DATA STRUCTURES AND ELEMENTS IN
PROCESS EQUIPMENT CATALOGUES –

Part 1: Generic structures for measuring equipment

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 61987-1 has been prepared by subcommittee 65E: Devices and integration in enterprise
systems, of IEC technical committee 65: Industrial-process measurement and control. It is an
International Standard.
This second edition cancels and replaces the first edition published in 2006. This edition
constitutes a technical revision.

– 6 – IEC 61987-1:2024 © IEC 2024
This edition includes the following significant technical changes with respect to the previous
edition:
a) Addition of a subclause “Digital communication” in Clause 5, in order to allow a more
comprehensive description of the properties of such an interface;
b) Alignment of clause headings, as described in the introduction, to correspond with those of
the IEC CDD.
The text of this International Standard is based on the following documents:
Draft Report on voting
65E/1113/FDIS 65E/1136/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61987 series, published under the general title Industrial-process
measurement and control – Data structures and elements in process equipment catalogues,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
In recent years, industry has become alert to the fact that a great deal of time and effort is
wasted in the transposition of measuring equipment data from one form to another. The
technical data of an instrument, for example, may exist at the manufacturer’s facility as two
separate data sets for paper and electronic presentation: the end-user requires much the same
data for works standards, engineering data bases or commercial data bases. In most cases,
however, the data cannot be automatically re-used because each application has its own
particular data storage format.
A second problem that belies the re-use of technical data is the content of the product
descriptions themselves. There is little agreement between manufacturers on what information
a technical data sheet should contain, how it should be arranged, or how the results, for example
of particular performance tests, should be presented. When transferring this information into a
data base, an end-user will always find gaps and proprietary interpretations that make the task
more difficult.
This part of IEC 61987 aims to solve these problems by defining a generic structure and its
content for industrial process measuring and control equipment. It builds upon the assumption
that, for a given class of measuring equipment, for example, pressure measuring equipment,
temperature measuring equipment or electromagnetic flow-measuring equipment, a set of non-
proprietary structures and product features can be specified. The resulting documents can not
only be exchanged electronically, but they can also be presented to humans in an easily
understandable form.
This part of IEC 61987 is applicable to electronic catalogues of process measuring equipment.
The structure also contains a great many product features that are common to measuring
equipment with binary output. Similarly, Annex B has been prepared with a view to future
standardisation.
This part of IEC 61987 is not intended as a replacement for existing standards, but rather as a
guiding document for all future standards which are concerned with the specifications of process
measuring equipment. Every revision of an existing standard should take into account the
structures and product features defined in Clause 5 or work towards a harmonisation.
Annex A contains a tabular overview of the classification and catalogue structure of process
measuring equipment. Annex B contains tables with a further sub-classification for specific
measured variables.
Wherever possible, existing terms from international standards have been used to name the
product features within the structures. In accordance with ISO 10241, Clause 3 contains a list
of terms, definitions and sources.
Documents created according to the standard are structured. A possible means of exchanging
structured information free of layout information is given by SGML (Standard Generalised
Mark-Up Language, ISO 8879) or XML (Extensible Mark-Up Language), which is derived from
it.
This part of IEC 61987 could also provide the basis for arranging of properties (data element
types) that conform to IEC 61360 or ISO 13584. This would require that the features, which in
this part of IEC 61987 can be textual units, graphical and tabular representations etc., be broken
down into properties (data element types) conformant to the said standards. For example, a
range would be expressed as a lower range-limit (LRL) and upper range-limit (URL) with unit of
measure; dimensions (L x B x H) as three separate elements, length, breadth and height with
unit of measure; or a derating curve as an appropriate series of data element pairs.

– 8 – IEC 61987-1:2024 © IEC 2024
This part of IEC 61987 conforms to ISO 15926-1 and -2 with respect to the data model and
associated reference data library (ISO 15926-4), for example, as used for the limited
classification structure. At the same time, it is also aligned to STEP: Standard for the Exchange
of Product Model Data. The data model and definitions of ISO 10303-221 use the ISO 15926-4
TS Reference Data Library as "library". The current standard can reproduce the data fields as
per this ISO 10303-221, including, for example, product structure data, dimensional data,
electrical connection data and product properties such as measuring range or power supply.
Since the publication of Edition 1 (2006) of this document a great deal of work has been done
on the development of the IEC Common Data Dictionary for equipment for industrial-process
automation. This, published as further parts of IEC 61987, covers not only measuring
instruments with a variety of inputs and outputs, but also final control elements, infrastructure
devices and in future process analysers.
For this reason, the title has been adjusted and the scope has been revised to reflect the current
content of the whole IEC 61987 standard series.
During the development of the IEC CCD a number of questions arose regarding the structure
proposed in this document, in particular the assignment of any digital communication interface
to the output. Although this is not strictly incorrect, it was thought that the properties of such an
interface could be better described separately. For this reason, a clause "Digital
communication" has been added to this Edition 2. In addition, the clause "Mechanical
construction" has been renamed "Mechanical and electrical construction" to reflect its true
content.
"Ordering information" is not found as a separate block in the IEC CDD, as it is assumed that
the properties there describe the type and particular instance of an already purchased device.
For an ordering process using IEC CDD properties, the necessary information is retrieved from
the "Identification" which also includes the ordering information.
"Certificates and approvals" can be found both in the device list of properties
(0112/2///61987#ABC156) and as a device aspect within the "device documents supplied"
(0112/2///61987#ABH517). This is also the location of the information contained in
"Documentation".
In preparing the current edition of this document all terms and definitions have been checked
and where necessary the references updated. Since the publication of Edition 1 in 2006 a
number of standards have been withdrawn. Where no suitable alternative source has been
found, a note to this effect has been added, but the original term and definition have been left
unchanged.
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
DATA STRUCTURES AND ELEMENTS IN
PROCESS EQUIPMENT CATALOGUES –

Part 1: Generic structures for measuring equipment

1 Scope
This part of IEC 61987 defines a generic structure in which product features of industrial
process measurement devices shall be arranged, in order to facilitate the understanding of
product descriptions when they are transferred from one party to another. It applies to the
production of catalogues supplied by the manufacturer of such devices and helps the user to
formulate their requirements.
This document will also serve as a reference document for all future standards which are
concerned with process measuring equipment.
In addition, this document also provides a basic structure for the production of further standards
listing the properties of process control equipment, for example, for actuators and infrastructure
devices.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60529:1989/AMD1:1999
IEC 60529:1989/AMD2:2013
IEC 60654-1:1993, Industrial-process measurement and control equipment – Operating
conditions – Part 1: Climatic conditions
IEC 60721-3 (all parts), Classification of environmental conditions – Classification of groups of
environmental parameters and their severities
IEC 60751:2022, Industrial platinum resistance thermometers and platinum temperature
sensors
IEC TR 61000-1-1:2023, Electromagnetic compatibility (EMC) – Part 1: General – Section 1:
Application and interpretation of fundamental definitions and terms
IEC 61069 (all parts), Industrial-process measurement, control and automation – Evaluation of
system properties for the purpose of system assessment
IEC 61298 (all parts), Process measurement and control devices – General methods and
procedures for evaluating performance
IEC 61326 (all parts), Electrical equipment for measurement, control and laboratory use – EMC
requirements
– 10 – IEC 61987-1:2024 © IEC 2024
IEC 61987-11, Industrial-process measurement and control – Data structures and elements in
process equipment catalogues – List of properties (LOPs) of measuring equipment for electronic
data exchange – Generic structures
ISO 3511-1:1977, Process measurement control functions and instrumentation – Symbolic
representation – Part 1: Basic requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
accuracy
inaccuracy
quality which characterizes the ability of a measuring instrument
to provide an indicated value close to a true value of the measured value under reference
conditions
Note 1 to entry: This term is used in the "true value" approach.
Note 2 to entry: Accuracy is all the better when the indicated value is closer to the corresponding true value.
Note 3 to entry: Inaccuracy as defined in IEC 61298-2 includes the errors of non-linearity, non-repeatability and
hysteresis.
Note 4 to entry: Accuracy can be expressed as percentage of reading, span or full range etc. or as an absolute
value
[SOURCE IEC 60050-311:—, 311-06-08, modified – measured value instead of measurand,
under reference conditions added, Notes 3 and 4 added]
3.2
accuracy class
category of instruments or components thereof, all of which are intended to comply with a set
of specifications regarding uncertainty
[SOURCE IEC 60050-311:—, 311-06-09 modified – "or components" added]
3.3
ambient temperature
temperature measured at a representative point within the local environment, including adjacent
heat generating equipment, in which the measurement and control equipment will normally
operate, be stored or transported
SEE: 3.15
3.4
ambient temperature limits
extreme values of ambient temperature to which a device may be subjected without permanent
impairment of operating characteristics
Note 1 to entry: The performance characteristics may be exceeded in the range between the limits of normal
operation and the operating temperature limits.
SEE: 3.3, 3.33
3.5
ambient temperature range
range of ambient temperatures within which a device is designed to operate within specified
accuracy limits
SEE: 3.31, 3.33
3.6
analog signal
signal each information parameter of which directly represents the respective variable quantity
Note 1 to entry: An analog signal may be a continuous-value signal or a discrete-value signal as well as a
continuous-time or a discrete-time signal. Examples may be the pressure in a pneumatic final controlling element
with continuous-value and continuous-time information parameter (value of the pressure) as well as a position-
modulated pulse signal as an output signal of a computer based controller.
[SOURCE: IEC 60050-351:2013, 351-41-24]
3.7
binary signal
discrete-value signal each information parameter of which may assume one of two values
[SOURCE: IEC 60050-351:2013, 351-41-21]
3.8
climate class
climatic conditions, i.e. ambient temperature, pressure and humidity, to which the measurement
equipment can be subjected during operation (including shutdown), transport and storage (over
land or sea)
3.9
degree of protection
extent of protection provided by an enclosure against access to hazardous parts, against
ingress of solid foreign objects and/or ingress of water, and verified by standardized test
methods
[SOURCE: IEC 60529:1989, 3.3]
3.10
dependability
extent to which a system can be relied upon to perform a required function under given
conditions at a given instant of time or over a given time interval, assuming that the required
external sources are provided
[SOURCE: IEC 61069-1:2016, 3.1.22]

– 12 – IEC 61987-1:2024 © IEC 2024
3.11
device
material element or assembly of such elements intended to perform a required function
Note 1 to entry: A device may form part of a larger device.
[SOURCE: IEC 60050-151: 2001, 151-11-20]
3.12
digital signal
signal each information parameter of which represents the respective variable quantity in coded
manner as a symbol of a character set
Note 1 to entry: In most technical cases a digital signal is discrete-value and discrete-time.
Note 2 to entry: A digital signal requires an agreement about the code between transmitter and receiver of the
signal.
Note 3 to entry: In many technical cases the symbols may be interpreted as numbers.
[SOURCE: IEC 60050-351:2013, 351-41-25]
3.13
drift
change in the indication of a measuring system, generally slow, continuous, not necessarily in
the same direction and not related to a change in the quantity being measured
[SOURCE: IEC 60050-311:—, 311-06-13, modified – quantity being measured for measurand]
3.14
electromagnetic compatibility
ability of equipment or a system to function satisfactorily in its electromagnetic environment
without introducing intolerable electromagnetic disturbances to anything in that environment
[SOURCE: IEC 60050-161:1990, 161-01-07]
3.15
environmental condition
characteristics of the environment which may affect the performance of the device or system
Note 1 to entry: Examples of environmental conditions are pressure, temperature, humidity, vibration, radiation.
[SOURCE: IEC 60050-151:2001, 151-16-03]
3.16
environmental condition class
alphanumeric character sequence denoting a set of environmental conditions to which the
equipment is or can be subjected to during operation
Note 1 to entry: The IEC 60721 series defines classes for climatic, mechanical and other environmental influences.
3.17
environmental influence
change in the output of an instrument caused solely by the departure of one of the specified
environmental conditions from its reference value, all other conditions being held constant
SEE: 3.21, 3.39
3.18
equipment
single apparatus or set of devices or apparatuses, or the set of main devices of an installation,
or all devices necessary to perform a specific task
Note 1 to entry: Examples of equipment are a power transformer, the equipment of a substation, measuring
equipment.
[SOURCE: IEC 60050-151:2001, 151-11-25]
3.19
hysteresis
property of a device or instrument whereby it gives different output values in relation to its input
values depending upon the directional sequence in which the input values have been applied
[SOURCE: IEC 61298-2:2008, 3.11]
3.20
influence of ambient temperature
change in zero (lower range-value) and/or span caused by a change in ambient temperature
from the reference temperature up to the limits of the ambient temperature range quoted in the
performance specifications
SEE: 3.17
3.21
influence quantity
quantity that is not the subject of the measurement and whose change affects the relationship
between the indication and the result of the measurement
[SOURCE: IEC 60050-311:—, 311-06-01]
3.22
integrity
assurance provided by the system that the tasks will be performed correctly unless notice is
given of any state of the system, which could lead to the contrary
[SOURCE: IEC 61069-1:2016, 3.1.37]
3.23
long-term drift
drift in output monitored for 30 days at 90 % of span
[SOURCE: IEC 61298-2:2008, 7.2, modified – subclause condensed]
3.24
maintainability
ability of an item under given conditions of use, to be retained in, or restored to a state in which
it can perform a required function, when maintenance is performed under given conditions and
using stated procedures and resources
[SOURCE: IEC 61069-1, 3.1.39]
– 14 – IEC 61987-1:2024 © IEC 2024
3.25
measured error
largest positive or negative value of error of the average upscale or downscale value at each
point of measurement
[SOURCE: IEC 61298-2:2008, 3.7, modified – "s" removed from error and value]
3.26
measured variable
quantity intended to be measured
[SOURCE: ISO/IEC Guide 99:2007, 2.3 – modified – term changed to reflect usage in control
technology, notes to entry removed]
3.27
measuring instrument
device intended to be used to make measurements, alone or in conjunction with supplementary
devices
[SOURCE: IEC 60050-311:—, 311-03-01]
3.28
measuring range
range of values defined by two extreme values within which a variable can be measured within
the specified accuracy
Note 1 to entry: The extreme values are usually termed the upper range-limit and the lower range-limit.
[SOURCE: IEC 60050-351:2013, 351-48-11 ]
3.29
measuring principle
measurement principle
phenomenon or process serving as the basi
...