Industrial-process measurement and control - Evaluation of system properties for the purpose of system assessment - Part 3: Assessment of system functionality

Describes in detail the method to be used to systematically assess the functionality of an industrial-process measurement and control system.

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

Décrit en détails la méthode à utiliser pour évaluer de manière systématique la fonctionnalité d'un système de mesure et commande des processus industriels.

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)

General Information

Status
Withdrawn
Publication Date
18-Aug-1996
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
19-Aug-1996
Completion Date
19-Aug-1996

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SLOVENSKI STANDARD
SIST EN 61069-3:1998
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
SIST EN 61069-3:1998 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
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

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in

utilisée sous quelque forme que ce soit et par aucun any form or by any means, electronic or mechanical,

procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in

copie et les microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.

International Electrotechnical Commission
3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 , e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
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voir vigueur
Pour prix, catalogue en
• • For price, see current catalogue
---------------------- Page: 2 ----------------------
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
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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

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.

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.

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.

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.

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.

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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.
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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.
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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
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
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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.
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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.
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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 selected, set up, arranged and combined to assemble functions to perform

industrial-process measurement and control tasks.

In practice the activity of configuring a system may require deep knowledge of system

architecture, module behaviour and module interfaces. The need for this knowledge can be

reduced by the presence of configuration facilities.

Facilities for configuration can be available at any level of the system. Methods to support

these facilities are shown in figure 3.
Configuration methods
Hardware Software
— Connecting by soldering
— Setting parameters
— Connecting by wiring
Selecting parameters
—Setting jumpers
— Selecting options
— Setting switches
—Programming
—Inserting printed circuit cards
— Inserting software modules
— Inserting modules
—Down-loading programmes
Figure 3 – Configuration methods

The configuration facilities are part of the system and considered as "supporting functions" if

they are fully described in the system specification document.

Depending on the system mode of operation ("on-line", "off-line", etc.) some of the

configuration actions may or may not be permissible. Some actions (such as module set-up,

changes to module connections, module insertion or removal, etc.) may only be possible

whilst the system is disabled from process operation.

It is also important to bear in mind that configuration changes can modify system properties

unexpectedly.
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1069-3 © IEC:1996 –
19 –

Configurability cannot be quantified as a number. It can be described in a qualitative manner

by detailing configuration actions and tools, and stating for each of these the know-how,

skills and time required.
4.5 Flexibility
4.5.1 General

The flexibility of a system depends on the way the system can be expanded, extended and

enhanced.

Flexibility is present when it is possible to add, remove, change and/or rearrange system

modules.
Flexibility cannot be expressed by a single measure.
4.5.2 Scaleability

A system can be designed in such a way, that it is possible to scale its size, such as by

adding or removing system modules.

The extent to which the system can be scaled can be assessed by analysis of architecture,

communication functions and shared resources.

Scaleability can be expressed by a qualitative description containing some quantified

elements.
4.5.3 Variability

A system may be designed in such a way that it is possible to vary the range of executable

tasks.

Variability can be assessed by analysis of the architecture, the degree of modularity, the

definition of interfaces between the modules and the number and scope of functions

provided by the individual modules.

Variability can be expressed by a qualitative description containing some quantified

elements.
4.5.4 Enhanceability

A system may be designed in such a way that it is possible to enhance certain system

properties.

Enhanceability can be assessed by analysing the architecture and the range of available

modules with alternative property values.
Some examples are:

modules with a larger main memory to allow a decrease in response time via reduced

data transfers;

modules which allow an increased number of iterations of mathematical procedures to

increase the accuracy of a calculated value;
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1069-3 © IEC:1996 – 21 –

– use of better protected input or output cards against electrical noise to increase the

system's security, or to increase the system's usability in areas where there are

explosion hazards.

The potential for improvement of these properties can extend beyond the requirements

stated in the system requirements document.

Enhanceability can be expressed by a qualitative description containing some quantified

elements.
5 Review of system requirements document (SRD)

The system requirements document should be reviewed to check that all the tasks to be

performed by the system and the functionality requirements have been addressed, and are

listed as described in IEC 1069-2.
The effectiveness of the functionality assessment is strongly dependent upon the
comprehensiveness of the statement of requirements.

Particular attention should be given to checking that the required configuration facilities and

the future requirements for the system have been stated and appropriately quantified, both

in relation to individual tasks as well as in relation to the total system mission.

Annex A gives guidance on the type of information the system requirements document

should give to enable the functionality properties to be assessed.
6 Review of system specification document (SSD)

The system specification document should be reviewed to check that the functions of the

system to perform the required tasks are listed as described in IEC 1069 -2.
Particular attention should be paid to check that information is given on:
– the system modules and elements, both hardware and software, supporting each
function;

– quantitative and/or qualitative data on the properties of these modules and elements,

and the availability of modules and elements with alternative properties;

– details of configuration tools, their use and constraints on the system operation;

– facilities provided by the system which, in the assembled operational system, support

analysis of functionality properties. Examples of these facilities are utilities for

listing all loaded programs, the supporting modules and elements;
– calculation of the spare capacity on memories devices, etc.;
– statistical analysis of system resource utilisation, etc.;

– listing any side-effects on any of the other system properties, which can occur due

to changes to the system.
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1069-3 ©
IEC:1996 – 23 –
7 Assessment procedure
7.1 General

The assessment should follow the procedure as laid down in clause 7 of IEC 1069-2.

The objective of the assessment shall be clearly stated. Guidance is given in 4.1 of IEC 1069-1.

The information given in the SRD and the SSD should be complete and precise to enable

the assessment of the functionality.

If at any phase of the assessment information is missing or incomplete, the originators of

the SRD and SSD should be consulted with specific
...

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