EN 61069-3:1996

SLOVENSKI STANDARD
01-november-1998
Industrial-process measurement and control - Evaluation of system properties for
the purpose of system assessment - Part 3: Assessment of system functionality
(IEC 61069-3:1996)
Industrial-process measurement and control - Evaluation of system properties for the
purpose of system assessment -- Part 3: Assessment of system functionality
Leittechnik für industrielle Prozesse - Ermittlung der Systemeigenschaften zum Zweck
der Eignungsbeurteilung eines Systems -- Teil 3: Eignungsbeurteilung der
Systemfunktionalität
Mesure et commande dans les processus industriels - Appréciation des propriétés d'un
système en vue de son évaluation -- Partie 3: Evaluation de la fonctionnalité d'un
système
Ta slovenski standard je istoveten z: EN 61069-3:1996
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
35.240.50 Uporabniške rešitve IT v IT applications in industry
industriji
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

NORME CEI
INTERNATIONALE IEC
61069-3
INTERNATIONAL
Première édition
STANDARD
First edition
1996-06
Mesure et commande dans les processus
industriels –
Appréciation des propriétés d'un système
en vue de son évaluation –
Partie 3:
Evaluation de la
fonctionnalité d'un système
Industrial-process measurement and control –
Evaluation of system properties for
the purpose of system assessment –
Part 3:
Assessment of system functionality
© IEC 1996 Droits de reproduction réservés — Copyright - all rights reserved
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1069-3 © IEC:1996 – 3 –
CONTENTS
Page
FOREWORD 5
INTRODUCTION 9
Clause
1 Scope 13.
2 Normative references 13
3 Definitions 13
4 Functionality properties 15
4.1 General 15
4.2 Functionality 15
4.3 Coverage 15
4.4 Configurability 17
4.5 Flexibility 19
5 Review of system requirements document (SRD) 21
6 Review of system specification document (SSD) 21
7 Assessment procedure 23
7.1 General 23
7.2 Analysis of the system requirements document and
system specification document 23
7.3 Designing the assessment programme 25
7.4 Assessment programme 27
8 Evaluation techniques 27
8.1 General 27
8.2 Coverage 27
8.3 Configurability 27
8.4 Flexibility 29
9 Execution and reporting of the assessment 29
Figures
1 General layout of IEC 1069 11
2 Functionality hierarchy 15
3 Configuration methods 17
Annexes
A Checklist on information to be given in the system requirements document 31
B Example analysis of system requirements document and system specification
document and documentation of collated information 33
C Bibliography 51
1069-3 © IEC:1996 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSE OF SYSTEM ASSESSMENT –
Part 3: Assessment of system functionality
FOREWORD
1)
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3)
The documents produced have the form of recommendations for international use and are published in the
form of standards, technical reports or guides and they are accepted by the National Committees in that
sense.
4)
In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5)
The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 1069-3 has been prepared by subcommittee 65A: System
aspects, of IEC technical committee 65: Industrial-process measurement and control.
The text of this standard is based on the following documents:
FDIS
Report on voting
65A/188/FDIS 65A/208/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.
The relation of this part to the other parts of IEC 1069 and the relative place of this part
within this standard is shown in figure 1.
Part 1 provides the overall guidance and as such is intended as a stand-alone publication.
Part 2 details the assessment methodology.
Parts 3 to 8 provide guidance on the assessment of specific groups of properties.

1069-3 © IEC:1996 -
7 -
The division of properties in parts 3 to 8 have been chosen so as to group together related
properties.
IEC 1069 consists of the following parts, under the general title:
Industrial-process
measurement and control - Evaluation of system properties for the purpose of system
assessment:
Part 1: General considerations and methodology
Part 2: Assessment methodology
Part 3: Assessment of system functionality
(under consideration)
Part 4: Assessment of system performance
(under consideration)
Part 5: Assessment of system dependability
Part 6: Assessment of system operability (under consideration)
Part 7: Assessment of system safety (under consideration)
Part 8: Assessment of non-task-related system properties
(under consideration)
Annexes A, B and C are for information only.

1069-3 © IEC:1996 - 9 -
INTRODUCTION
This part of IEC 1069 deals with the method which should be used to assess the
functionality of industrial-process measurement and control systems. Assessment of a
system is the judgement, based on evidence, of a system's suitability for a specific mission
or class of missions.
To obtain total evidence would require a complete (i.e. under all influencing conditions)
evaluation of all system properties relevant to the specific mission or class of missions.
Since this is rarely practical, the rationale on which an assessment of a system should be
based is:
-
to identify the criticality of each of the relevant system properties;
-
to plan for evaluation of the relevant system properties with a cost-effective dedication
of effort to the various properties.
In conducting an assessment of a system it is crucial to bear in mind the need to gain a
maximum increase in confidence in the suitability of a system within practical cost and time
constraints.
An assessment can only be carried out if a mission has been stated (or given) or if any
mission can be hypothesized. In the absence of a mission, no assessment can be made;
however, evaluations (as defined in IEC 1069-1) can still be specified and be carried out for
use in assessments performed by others.
In such cases, the standard can be used as a guide for planning an evaluation and it
provides procedures for performing evaluations, since evaluations are an integral part of
assessment.
1069-3 © IEC:1996 - 11 -
Part 1:
General considerations
and methodology
Scope
Definitions
Basis of assessment
Assessment consideration
The system
Properties
Influencing conditions
Assessment procedure
Definition of the objectives
Design and layout
Part 2:
Methodology
Analysis of objectives
Analysis of system requirements
Analysis of system specification
I
Planning Design of assessment programme
Facilities
Expertise
Time
Funds
Execution of assessment programme
Protocol
Monitor and control
Part 3: Functionality
Part 4: Performance
Part 5: Dependability
Part 6: Operability
Part 7: Security
Part 8: NTR properties
Assessment report
Figure 1 - General layout of IEC 1069

1069-3 © IEC:1996 – 13 –
INDUSTRIAL-PROCESS MEASUREMENT AND CONTROL –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSE OF SYSTEM ASSESSMENT –
Part 3: Assessment of system functionality
1 Scope
This part of IEC 1069 describes in detail the method to be used to systematically assess the
functionality of an industrial-process measurement and control system.
The assessment methodology detailed in IEC 1069-2 is applied to obtain the functionality
assessment programme.
The subsidiary functionality properties are analysed, and criteria to be taken into account
when assessing functionality are described.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 1069. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties making
agreements based on this part of IEC 1069 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 1069-1: 1991, Industrial-process measurement and control – Evaluation of system
properties for the purpose of system assessment – Part 1: General considerations and
methodology
IEC 1069-2: 1993, Industrial process measurement and control – Evaluation of system
properties for the purpose of system assessment – Part 2: Assessment methodology
3 Definitions
For the purpose of this part of IEC 1069 the following definitions apply:
3.1 functionality:
The extent to which the system provides, and facilitates assembly of,
functions to perform industrial process measurement and control tasks.
3.2 coverage: The extent to which the system provides functions to perform industrial-
process measurement and control tasks.
3.3 configurability: The extent to which the system facilitates selection, setting up and
arrangement of its modules to perform industrial-process measurement and control tasks.
3.4 flexibility: The extent to which the system can be adapted.

1069-3 ©
IEC:1996 – 15 –
4 Functionality properties
4.1 General
A system is able to perform the required industrial-process measurement and control tasks
if the functions provided by the system cover these tasks. The extent to which this is the
case can be expressed as the property coverage.
For a system designed for a set of rigid and fixed tasks, coverage can describe fully th
e .
functionality of a system.
The tasks required, however, can differ for different applications of the system or the tasks
can change or be extended over time due to changes in the industrial process or
arrangements in control strategy. To cope with this, the system should provide means for
configuring the selection and arrangement of modules, and should have an architecture
which provides flexibility for additions and. modifications.
To fully assess the functionality of a system it is therefore necessary to identify and assess
the subsidiary properties that determine functionality.
The relation between functionality and its subsidiary properties is shown in figure 2.
Functionality
Coverage Configurability Flexibility
Figure 2 – Functionality hierarchy
4.2 Functionality
Functionality cannot be assessed directly and cannot be described by a single measure. It is
necessary to assess each subsidiary property individually.
Some of its sub-properties can be expressed in quantitative terms as an absolute or relative
value, others can only be described in a qualitative way with some quantitative elements.
_
The sub-properties are deterministic in nature.
When assessing the functionality of a system the availability of facilities necessary to
support the subsidiary properties should be taken into account.
4.3 Coverage
Coverage is determined by:
– the range of distinct functions provided, each differentiated by type, execution
frequency, data volume, etc.;
–
the way in which the functions cooperate, as determined by the architecture, to
perform the task(s) required;
–
the number of replications available of each function, as determined by the way in
which the system modules provide these functions and how these functions are allocated
within the modules.
1069-3 © IEC:1996 – 17–
The way in which the individual functions are set up and combined to perform tasks can
impose interdependent limits on each function. It can also impose limits on the simultaneous
use of separate functions when there is sharing of system resources.
The coverage of the system should be quantified as a coverage factor with reference to the
totality of tasks required by the system mission. If appropriate, partial coverage factors
should be expressed for each individual task.
4.4
Configurability
Configurability is dependent upon the architecture of the system and the ease with which
modules can be
...