EN 61175-1:2015

Industrial systems, installations and equipment and industrial products - Designation of signals - Part 1: Basic rules

IEC 61175-1:2015 provides rules for the composition of designations for the identification of signals and signal connections. This includes the designation of power supply. This part of IEC 61175 is applicable to all types of signals within an industrial system, installation and equipment and industrial products. It deals with the information aspect of signals and not with their physical implementation. This first edition cancels and replaces the second edition of IEC 61175 published in 2005 and constitutes a technical revision. It includes the following changes: an improved description of the principles for use and a strict separation between the physical aspect of a signal and its associated information, focusing on the latter. This horizontal standard is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 108.

Industrielle Systeme, Anlagen und Ausrüstungen und Industrieprodukte - Kennzeichnung von Signalen - Teil 1: Allgemeine Regeln

Systèmes, installations, appareils et produits industriels - Désignation des signaux - Partie 1: Règles de base

L'IEC 61175-1:2015 établit des règles pour la composition des désignations pour l'identification des signaux et des connexions de signaux. Elle intègre la désignation de l'alimentation électrique. Elle est applicable à tous les types de signaux au sein d'un système, d'une installation et d'un appareil, et de produits industriels. Elle traite l'aspect information des signaux et non leur mise en uvre physique. Cette première édition annule et remplace la deuxième édition de l'IEC 61175 parue en 2005 et constitue une révision technique. Cette édition inclut les modifications suivantes: une description améliorée des principes d'utilisation et une séparation stricte entre l'aspect physique d'un signal et les informations associées relatives à ce dernier. Elle a le statut d'une norme horizontale conformément au Guide 108 de l'IEC.

Industrijski sistemi, inštalacije in oprema ter industrijski proizvodi, oznake signalov - 1. del: Osnovna pravila (IEC 61175-1:2015)

Ta del standarda IEC 61175 določa pravila za sestavo oznak za identifikacijo signalov in signalnih povezav. To vključuje oznako za napajanje. Ta del standarda IEC 61175 se uporablja za vse vrste signalov v industrijskih sistemih, inštalacijah in opremi ter industrijskih proizvodih. V njem je obravnavan informacijski vidik signalov in ne njihovo fizično izvajanje.
S področja uporabe standarda so izključena splošna pravila za predstavitev informacij pri vmesnikih človek-stroj. Ta del standarda IEC 61175 se prav tako ne uporablja za identifikacijo napeljave, terminalov, ocevja in drugih povezav strojne opreme.
OPOMBA: Za namen označevanja žic glejte standard IEC 62491. Ta horizontalni standard je namenjen predvsem tehničnim odborom za pripravo standardov v skladu z načeli vodila IEC Guide 108. Ena od pristojnosti tehničnih odborov je, da med pripravo publikacij uporabljajo horizontalne standarde, kadar je to primerno. Vsebina tega horizontalnega standarda se ne uporablja, razen če je izrecno navedena ali zajeta v ustreznih publikacijah.

General Information

• Status: Published
• Publication Date: 27-Aug-2015
• Withdrawal Date: 24-Jun-2018
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: CLC/SR 3 - Information structures, documentation and graphical symbols
• Drafting Committee: IEC/TC 3 - IEC_TC_3
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 28-Aug-2015
• Completion Date: 28-Aug-2015
• Ref Project: SIST EN 61175-1:2015 - Industrial systems, installations and equipment and industrial products, designation of signals - Part 1: Basic rules (IEC 61175-1:2015)

Relations

• Replaces: EN 61175:2005 - Industrial systems, installations and equipment and industrial products - Designation of signals
• Effective Date: 28-Jan-2023

Overview

EN 61175-1:2015 (IEC 61175-1:2015) specifies basic rules for the designation of signals and signal connections in industrial systems, installations, equipment and industrial products. The standard defines how to compose signal names (including power-supply designations) and emphasizes the information aspect of a signal - strictly separating the informational identity from its physical implementation. This edition replaces EN 61175:2005 and refines principles for use to support consistent signal identification and metadata across engineering documentation and digital interfaces.

Key topics and requirements

• Basic principles and terminology
  • Definitions of signal, source/destination, and information object.
  • Emphasis on separation between information content and physical transmission.
• Signal classification and name domain
  • Rules for categorizing signals and defining the domain (object) that gives context to a name.
• Structure of signal designation
  • Components covered: object designation, optional prefix, signal name, signal connection identifier, and signal connection characteristics.
  • Guidance on recommended characters and formation rules for reporting vs. controlling signals.
• Signal connection identification and grouping
  • How to identify and group signals within a connection network and when using concatenated reference designations.
• Interfaces and data exchange
  • Identification practices for I/O interfaces, internal/external buses and logic communication.
  • Treatment of metadata and data element definitions (annex on data element types).
• Presentation and HMI
  • Rules for representing vs. presenting signal designations in diagrams, human-machine interfaces and documentation.
• Normative and informative annexes
  • Letter codes for signal names, binary logic representation, examples, communication models and DET (data element type) definitions.

Applications and users

EN 61175-1:2015 is intended for professionals who need consistent, unambiguous signal identification across disciplines:

• Control system engineers (PLC/SCADA mapping and I/O tagging)
• Electrical and instrumentation designers (wiring lists, terminal blocks)
• Project documentation authors (schematics, signal lists, HMI content)
• System integrators and OEMs (interoperability and configuration)
• Standards committees and technical writers preparing domain standards aligned to IEC Guide 108

Practical benefits include reduced wiring/logic errors, clearer cross-discipline documentation, better support for automated data exchange, and consistent HMI displays.

Related standards

• IEC 81346 series (reference designations / structuring principles)
• IEC 61082-1 (document preparation rules)
• Other referenced standards for metadata and harmonized terminology cited in the annexes

Keywords: EN 61175-1:2015, IEC 61175-1:2015, designation of signals, signal naming, signal identification, signal connection identifiers, industrial systems, HMI, I/O mapping, signal metadata.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2015
Industrijski sistemi, inštalacije in oprema ter industrijski proizvodi, oznake
signalov - 1. del: Osnovna pravila (IEC 61175-1:2015)
Industrial systems, installations and equipment and industrial products, designation of
signals - Part 1: Basic rules (IEC 61175-1:2015)
Industrielle Systeme, Anlagen und Ausrüstungen und Industrieprodukte, Kennzeichnung
von Signalen - Teil 1: Allgemeine Regeln (IEC 61175-1:2015)
Systèmes industriels, installations et appareils, et produits industriels, Désignations des
signaux - Partie 1: Règles de base (IEC 61175-1:2015)
Ta slovenski standard je istoveten z: EN 61175-1:2015
ICS:
29.020 Elektrotehnika na splošno Electrical engineering in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61175-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2015
ICS 29.020 Supersedes EN 61175:2005
English Version
Industrial systems, installations and equipment and industrial
products - Designation of signals - Part 1: Basic rules
(IEC 61175-1:2015)
Systèmes, installations, appareils et produits industriels - Industrielle Systeme, Anlagen und Ausrüstungen und
Désignation des signaux - Partie 1: Règles de base Industrieprodukte, Kennzeichnung von Signalen -
(IEC 61175-1:2015) Teil 1: Allgemeine Regeln
(IEC 61175-1:2015)
This European Standard was approved by CENELEC on 2015-06-25. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61175-1:2015 E
European foreword
The text of document 3/1214A/FDIS, future edition 1 of IEC 61175-1, prepared by IEC/TC 3
"Information structures and elements, identification and marking principles, documentation and
graphical symbols" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at (dop) 2016-03-25
national level by publication of an identical national
standard or by endorsement
(dow) 2018-06-25
• latest date by which the national standards conflicting with
the document have to be withdrawn

This document supersedes EN 61175:2005.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 61175-1:2015 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60027 NOTE Harmonized in EN 60027 series.
IEC 60445 NOTE Harmonized as EN 60445.
IEC 60447 NOTE Harmonized as EN 60447.
IEC 60747 NOTE Harmonized in EN 60747 series.
IEC 61131 NOTE Harmonized in EN 61131 series.
IEC 61355-1 NOTE Harmonized as EN 61355-1.
IEC 61360-1 NOTE Harmonized as EN 61360-1.
IEC 61666 NOTE Harmonized as EN 61666.
IEC 61850 NOTE Harmonized in EN 61850 series.
IEC 62491 NOTE Harmonized as EN 62491.
IEC 62744 NOTE Harmonized as EN 62744.
IEC 81346-2 NOTE Harmonized as EN 81346-2.
IEC 80000 NOTE Harmonized in EN 80000 series.
ISO 21549-7:2007 NOTE Harmonized as EN ISO 21549-7:2007 (not modified).
ISO 80000 NOTE Harmonized in EN ISO 80000 series.

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is
available here: www.cenelec.eu.

Publication Year Title EN/HD Year
IEC 61082-1 -  Preparation of documents used in EN 61082-1 -
electrotechnology -
Part 1: Rules
IEC 81346-1 -  Industrial systems, installations and EN 81346-1 -
equipment and industrial products -
Structuring principles and reference
designations -
Part 1: Basic rules
IEC/TS 62720 -  Identification of units of measurement for - -
computer-based processing
IEC 61175-1 ®
Edition 1.0 2015-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
HORIZONTAL STANDARD
NORME HORIZONTALE
Industrial systems, installations and equipment and industrial products –

Designation of signals –
Part 1: Basic rules
Systèmes, installations, appareils et produits industriels –

Désignation des signaux –
Partie 1: Règles de base
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.020 ISBN 978-2-8322-2677-3

– 2 – IEC 61175-1:2015 © IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Basic principles . 11
4.1 General principles on signal transfer and signal naming . 11
4.2 Signal classification . 12
4.3 Signal name domain . 13
5 Designation of signals . 14
5.1 Structure of the signal designation . 14
5.1.1 General . 14
5.1.2 Object designation . 15
5.1.3 Prefix . 15
5.1.4 Signal name . 16
5.1.5 Signal connection identifier . 19
5.1.6 Signal connection characteristics . 19
5.2 Recommended characters . 19
5.3 Forming signal designations . 20
5.3.1 Reporting signals . 20
5.3.2 Controlling signals . 25
6 Identification of signals in the signal connection network . 26
6.1 General . 26
6.2 Pre-defined signal names . 27
6.3 Grouping of signals . 28
6.3.1 General . 28
6.3.2 Packaging of signals in signal carrying medium . 28
6.3.3 Grouping of signals for presentation . 29
7 Signal identification in interfaces for data exchange . 29
7.1 General . 29
7.2 Interface between electric circuit and programmable devices, I/O . 29
7.3 Interface for logic communication . 29
8 Signal presentation . 29
8.1 Representation vs. presentation of a signal designation . 29
8.2 Human machine interface, HMI . 30
8.3 Presentation in documentation . 30
8.4 Presentation of metadata for signals . 31
Annex A (normative) Letter codes for use in signal names . 33
A.1 Letter codes for variables . 33
A.2 Letter codes used as modifiers . 34
A.3 Identification of certain designated conductors . 34
Annex B (informative) Binary logic representation . 35
B.1 General . 35
B.2 Negated signal . 35
Annex C (informative) Examples for signal lists including signal connection identifiers . 37

IEC 61175-1:2015 © IEC 2015 – 3 –
C.1 Presentation of voltage measurement signal, class M . 37
C.2 Presentation of a controlling signal, class C . 39
Annex D (informative) Generic communication needs in a process. 40
D.1 Process model . 40
D.2 Signal connection and signal presentation media . 40
D.2.1 General . 40
D.2.2 Wiring . 41
D.2.3 Internal bus . 41
D.2.4 External bus . 41
D.2.5 Presentation in the human interface, HMI . 41
D.2.6 Other human presentation . 41
D.3 Applicability of signal designations . 42
D.3.1 In electrical system . 42
D.3.2 In control devices (with internal numerical communication) . 42
D.3.3 In external communication . 42
D.3.4 In the HMI . 42
Annex E (informative) Restructuring of information for communication purposes . 43
E.1 General . 43
E.2 Data objects . 43
E.2.1 Packing of data . 43
E.2.2 Object designation and address structure . 43
E.2.3 Information content (Information object) . 44
E.2.4 Descriptive parameters . 44
Annex F (normative) Data element type definitions . 46
F.1 General . 46
F.2 Source definitions of DETs and classes of DETs in this part of IEC 61175 . 46
F.2.1 Definitions of classes of DETs . 46
F.2.2 Definition of DETs associated with class AAF525 . 47
F.2.3 Definition of DETs associated with class AAF526 . 47
Bibliography . 48

Figure 1 – Illustration of relationship of terminology . 7
Figure 2 – Signal with source and destination(s) . 11
Figure 3 – Information object transmitted via different signal carrying and connection
media . 11
Figure 4 – Different signals caused by processing/logical linking . 12
Figure 5 – Relation between controlling and reporting signals . 13
Figure 6 – Object serving as signal name domain . 14
Figure 7 – Signal designation and signal connection identification . 15
Figure 8 – Signal name structure . 16
Figure 9 – Examples of reporting type of signals . 21
Figure 10 – Example of an indication signal . 22
Figure 11 – Example of an event signal . 22
Figure 12 – Example of measuring signals . 23
Figure 13 – Example of an analogue measuring signal transmitted in different forms . 23
Figure 14 – Example of signal connection characteristics related to measuring signals . 24
Figure 15 – Example of power supply designation . 24

– 4 – IEC 61175-1:2015 © IEC 2015
Figure 16 – Examples of typical controlling type of signals . 25
Figure 17 – Example of a command signal . 26
Figure 18 – Example of a signal for setting value . 26
Figure 19 – Signal connection identifiers in a single connection network . 27
Figure 20 – Example of signal connection identifiers in a current measuring circuit . 27
Figure 21 – Signal connection identifiers by internal signal name . 28
Figure 22 – Use of concatenated reference designations in a plant . 31
Figure 23 – Metadata representing a signal and corresponding XML file . 32
Figure B.1 – Signal states of binary signals . 35
Figure B.2 – Example of a negated signal . 36
Figure C.1 – Voltage measurement, reporting signal class M . 38
Figure C.2 – Command signal for a disconnector, controlling signal class C . 39
Figure D.1 – Communication model based on IEC 81346-2 . 40
Figure E.1 – Communication of the signal information as attribute to a data object . 43

Table 1 – Letter codes for signal classes . 17
Table 2 – Examples of short names . 17
Table 3 – Examples of basic signal names . 18
Table A.1 – Letter codes for variables based on International Standard 80000,
Quantities and units . 33
Table A.2 – Letter codes used as modifiers . 34
Table A.3 – Identification of certain designated conductors . 34
Table E.1 – Data attribute examples . 45

IEC 61175-1:2015 © IEC 2015 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL SYSTEMS, INSTALLATIONS AND
EQUIPMENT AND INDUSTRIAL PRODUCTS –
DESIGNATION OF SIGNALS –
Part 1: Basic rules
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 in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for 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
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61175-1 has been prepared by IEC technical committee 3:
Information structures and elements, identification and marking principles, documentation and
graphical symbols.
It has the status of a horizontal standard in accordance with IEC Guide 108.
This first edition cancels and replaces the second edition of IEC 61175 published in 2005.
This edition constitutes a technical revision.
Further parts of IEC 61175 may be added as Technical Specifications relating to different
domains. Additional parts may be application guides for designation of signals in specific
applications such as communication protocols and other software systems.

– 6 – IEC 61175-1:2015 © IEC 2015
This edition includes the following significant technical changes with respect to
IEC 61175:2005:
– an improved description of the principles for use; and
– a strict separation between the physical aspect of a signal and its associated information,
focusing on the latter.
The text of this standard is based on the following documents:
FDIS Report on voting
3/1214A/FDIS 3/1221/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61175 series, published under the general title Industrial systems,
installations and equipment and industrial products – Designation of signals, can be found on
the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
IEC 61175-1:2015 © IEC 2015 – 7 –
INTRODUCTION
The intention of this part of IEC 61175 is to establish rules and requirements for the
designation of signals, and furthermore to make recommendations on useful presentations of
these.
Basically, a signal designation is associated with the signal over its whole lifetime, which
means from the beginning of the design stage until the signal is no longer needed.
The change of medium for the transfer of a signal because of a physical rebuilding of an
installation will not cause a change of the identification of this signal if its semantic meaning is
maintained. Signals represent information. For communication purposes the information has
to be represented as data. The information can be more or less complex. In simple cases, the
information can be represented as a single Boolean variable, without internal structure. In
more complex cases, like in computer communication via data networks, the information can
be packaged in more complex objects, with internal structure, which are transferred with
suitable protocols. The implementation can be done in different ways depending on which
technology, protocol, etc. is being used. Figure 1 illustrates the terminology.
Concept model
formally
Knowledge (concepts in the “Reality” of
described by
an individual)
communicated as
Information object Information Information model
describes
assembled formally
Metadata object (unit of structured (communicatable (concepts as communicated
to described by
information) knowledge) in a given context)
represented as represented as
Data model
describes
Data object (unit of assembled Data formally
Metadata (information as represented
structured data) to (symbols with meaning) described by
in a given implementation)
for transfer represented as
assembled to
describes
Symbol
Signal metadata Signal
(e.g. characters)
is transferred by
Signal carrying medium
(e.g. light)
is transported by
Signal connection medium
(e.g. fibre)
IEC
Figure 1 – Illustration of relationship of terminology
The principles described in this part of IEC 61175 are closely related to other International
Standards such as IEC 81346-1, IEC 81346-2, IEC 61666 and IEC 81714-3. An information
model for the interrelations is provided in IEC TS 62771.

– 8 – IEC 61175-1:2015 © IEC 2015
INDUSTRIAL SYSTEMS, INSTALLATIONS AND
EQUIPMENT AND INDUSTRIAL PRODUCTS –
DESIGNATION OF SIGNALS –
Part 1: Basic rules
1 Scope
This part of IEC 61175 provides rules for the composition of designations for the identification
of signals and signal connections. This includes the designation of power supply.
This part of IEC 61175 is applicable to all types of signals within an industrial system,
installation and equipment and industrial products. It deals with the information aspect of
signals and not with their physical implementation.
Excluded from the scope are general rules for the presentation of information in human
machine interfaces. This part of IEC 61175 is also not applicable for the identification of
wiring, terminals, piping and other hardware connections.
NOTE For the purpose of marking of wires, see IEC 62491.
This horizontal standard is primarily intended for use by technical committees in the
preparation of standards in accordance with the principles laid down in IEC Guide 108.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
horizontal standards in the preparation of its publications. The contents of this horizontal
standard will not apply unless specifically referred to or included in the relevant publications.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61082-1, Preparation of documents used in electrotechnology – Part 1: Rules
IEC 81346-1, Industrial systems, installations and equipment and industrial products –
Structuring principles and reference designations – Part 1: Basic principles
IEC 62720, Identification of units of measurement for computer-based processing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
object
entity treated in a process of development, implementation, usage and disposal
Note 1 to entry: The object may refer to a physical or non-physical “thing”, i.e. anything that might exist, exists or
did exist.
IEC 61175-1:2015 © IEC 2015 – 9 –
Note 2 to entry: The object has information associated with it.
[SOURCE: IEC 81346-1:2009, definition 3.1]
3.2
information object
fixed and structured amount of information that can be managed and interchanged as a unit
amoung users and systems
Note 1 to entry: This unit need not be human perceptible. Information objects are often stored as data.
Note 2 to entry: “Users” refers in this definition to users of information and “systems” refers to systems managing
information and documentation.
3.3
data object
collection of data that has an agreed grouping between the sender and the receiver and can
be identified as a complete entity
[SOURCE: ISO 21549-7:2007, 3.12, modified — “Natural grouping” has been changed to
“agreed grouping between sender and receiver”.]
3.4
signal
agreed representation of an information object conveyed among objects
Note 1 to entry: The agreed representation is a data object. The information object can be used to express a
binary state or analogue variable or have a more complex structure.
Note 2 to entry: The representations of the information object e.g. potential level, current level, data format,
protocol, etc., are conveyed in a suitable signal connection medium.
Note 3 to entry: Complex information objects usually need a number of successive conversions until they reach a
representation suitable for transfer in a signal connection medium.
Note 4 to entry: The agreement between sender(s) and receiver(s) is necessary in order to generate and interpret
the representation correctly. In simple cases it is implicit, in other cases it has to be explicitly specified as a
protocol, etc.
Note 5 to entry: The representations of the information object can be conveyed directly from source to destination
(synchronous communication) on the signal connection medium, or intermediately stored (by the sender) in a place
where the intended receivers can get them (asynchronous communication).
3.5
signal name
identifier of the information object represented by a signal
3.6
signal designation
unambiguous identifier of a signal within a system
3.7
object designation
identifier of a specific object in a given context
EXAMPLES Reference designation, type number, serial number, name.
[SOURCE: IEC 61355-1:2008, definition 3.13]
3.8
reference designation
identifier of a specific object formed with respect to the system of which the object is a
constituent, based on one or many aspects of that system

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[SOURCE: IEC 81346-1:2009, definition 3.11]
3.9
signal connection
established communication path between different objects used for transmission of signals
Note 1 to entry: A signal connection uses one signal connection medium only. Change of medium takes place in
the objects.
3.10
signal connection network
signal connections that transfer the same information object
Note 1 to entry: A signal connection network can use different media.
3.11
signal connection identifier
identifier of a specific signal connection
Note 1 to entry: The term for this definition was formerly "signal variant", which is now deprecated.
3.12
signal connection medium
(physical) medium on which the signal is transported from one (physical interface) point to
another
EXAMPLES Electric wire, optic fibre, space.
3.13
signal carrying medium
physical quantity or data transfer protocol used to transfer the signal
EXAMPLES Current, potential, bus protocol.
3.14
domain
distinguished part of an abstract or physical space where something exists
3.15
signal name domain
domain in which signal names are unambiguously distinguished
3.16
signal presentation
means of communicating an information object in human-interpretable form
3.17
signal class
group of signals defined in accordance with a classification scheme based on the purpose of
the signals
3.18
signal class code
coded designation of a signal class
3.19
signal connection characteristics
optional description of technical characteristics of the signal connection
Note 1 to entry: The term for this definition was formerly "additional information", which is now deprecated.

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4 Basic principles
4.1 General principles on signal transfer and signal naming
Signals are representations of information objects that are exchanged among objects.
Normally a signal has one source and one or many destinations (see Figure 2).
Destination
Signal with parallel transmission paths
Signal
Signal Signal
Source Destination Source Destination
Signal
Destination
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Figure 2 – Signal with source and destination(s)
The transmission of a signal from source to destination may require one or many signal carrying media, see
Figure 3, which in turn requires signal connection media in order to operate.
If a change of a signal carrying medium to another or a change of a signal connection medium
to another is required, transformations can be necessary.
At such transformations, the represented information object shall remain unchanged, see
Figure 3.
Signal connection medium 1: Signal connection medium 2: Signal connection medium 3:
e.g. copper wire e.g. space e.g. optical fibre
Signal carrying medium 1: Signal carrying medium 2: Signal carrying medium 3:
e.g. current e.g. radio frequency e.g. light
Source Transformation * Transformation * Destination
Signal 1 Signal 1 Signal 1
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* without change of information object
Figure 3 – Information object transmitted via
different signal carrying and connection media
If the information object of a signal is intentionally processed, for example the information
object being delayed or being subject to a logic condition, a new signal shall be created, see
Figure 4.
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Signal 1 Signal 2
Source Processing Destination
e.g. “limit
supervision”
e.g. “tempErature” e.g. “switch off”
Signal 1 Signal 4
Source Destination
Signal 2
Source Processing/linking
Signal 3 Signal 5
Source Destination
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Figure 4 – Different signals caused by processing/logical linking
If the information object with respect to the intended information exchange is modified, a
different signal name shall be applied.
The identification of the information object – the signal name – is therefore the most basic
issue in the construction of the signal designation (see Clause 5).
4.2 Signal classification
The signal may be classified according to different characteristics. The signal classification
provided in this part of IEC 61175 is based on the purpose of the signal.
Two groups of signals exist with respect to their treatment in designations:
• reporting signals, and
• controlling signals.
The characterization of these two groups is based on the direction of the information flow
related to the considered objects (see Figure 5). As a signal is transmitted between two or
more objects, one of the objects needs to be appointed as the main object (see 5.1).
The “main object” is an object that is in most cases associated with the main process
concerned, as opposed to, for example controlling or monitoring processes. Those are
considered to be related to auxiliary processes.
EXAMPLES:
A switch in a control panel provides a signal for closing a circuit breaker in the main process. The circuit breaker is
then considered as the main object and the signal is a controlling one. The circuit breaker provides a signal
representing its closed position for indication in a control panel. The circuit breaker is also in this case considered
the main object and therefore the signal is a reporting one.

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Controlling signal
Controlling object Controlled object
e.g. e.g.
control panel circuit breaker
Reporting signal
“Main object”
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Figure 5 – Relation between controlling and reporting signals
The two groups are further split into signal classes:
• Reporting signal group contains the following classes:
alarm signal, event signal, indication signal, measuring signal (including power supply);
• Controlling signal group contains the following classes:
command signal, setting value signal.
Table 1 provides these signal classes together with associated letter codes to be used as part
of the signal name.
4.3 Signal name domain
The signal name domain defines the domain inside which a given signal name shall be
unambiguous. For identification of signal name domains see 5.1.2. As a consequence signal
names may be repeatedly used if existing in different unambiguously identified signal name
domains. Different possibilities exist for defining such a domain:
• Both, source and destination of the signal are constituents of the object serving as domain
(see Figure 6 a). This shall be applicable for all signals if such a common object exists.
• The object that constitutes or contains the destination of a signal is chosen as domain
(see Figure 6 b). This is mainly applicable for controlling signals.
• The object that constitutes or contains the source of a signal is chosen as domain (see
Figure 6 c). This is mainly applicable for reporting signals.

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Signal name domain
Signal A
Control function
a)
Pumping
function
Signal B
Indicating
function
Signal name domain
Source Destination
Signal A
Control panel Pump
b)
Signal name domain
Source Destination
Signal B
Pump Control panel
c)
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Figure 6 – Object serving as signal name domain
5 Designation of signals
5.1 Structure of the signal designation
5.1.1 General
A signal designation shall unambiguously identify a signal along all signal connections
belonging to a signal connection network. It shall be independent of any signal connection
and signal carrier medium. The signal designation consists of the following parts:
• object designation of the signal name domain (see 5.1.2);
• prefix for signal name (see 5.1.3);
• signal name (further substructure, see 5.1.4).
For the purpose of identifying a specific signal connection in a signal connection network or
for providing additional information related to that connection, the signal designation may be
supplemented by
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• signal connection identifier (see 5.1.5);
• signal connection characteristics (see 5.1.6).
The structure of a signal designation shall be as shown in Figure 7.
Detailed rules on presentation of signal designations in documents are provided in
IEC 61082-1.
Signal designation with signal connection information
Signal designation
Signal connection information
Object designation ;Signal name :Signal connection id (Sign. Conn. char.)
Designation of the object
which is the domain of the
signal designation
Prefix sign indicating the
signal name
Signal name
Character indicating signal
connection information
Signal connection identification
(optional)
Signal connection characteristics
(optional)
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Figure 7 – Signal designation and signal connection identification
5.1.2 Object designation
The object designation is an identifier of the signal name domain inside which the signal name
is unambiguous and valid. The object designation shall be (or shall be made) unambiguous in
the given or planned system context.
The choice of the object serving as signal name domain shall be based either on identifying
the overall object of which the source and destination are constituents, or on the
denomination of a main object in the signal connection network as described in 4.2. This
means that the signal name domain is identified by the object designation of the overall object
or of the controlled or the reporting object.
A reference designation in accordance with IEC 81346-1 is considered as an unambiguous
designation of an object.
If a reference designation in accordance with IEC 81346-1 is used, it shall be applied as
object designation.
5.1.3 Prefix
The signal name shall be preceded by a prefix sign, namely the character “;” (semicolon).

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In presentations the prefix sign may be omitted if the context is clear, for example in a signal
list in which the meaning of this piece of information is indicated in the column header.
However the prefix sign shall be presented when a signal name is presented together with a
preceding object designation.
5.1.4 Signal name
The signal name shall identify the information object by providing short but significant
information on that information object.
It is composed of the following elements:
• signal class (optional); consisting of a code (see Table 1);
• short name (optional), representing the related sourc
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