Normas International Electrotechnical Commission

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 specifications, 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

INTRODUCTION

This Part of IEC 61131 constitutes Part 1 of a series of standards on programmable controllers

and their associated peripherals and should be read in conjunction with the other parts of the

series.

Where a conflict exists between this and other IEC standards (except basic safety standards),

the provisions of this standard should be considered to govern in the area of programmable

controllers and their associated peripherals.

The purposes of this standard are:

Part 1 establishes the definitions and identifies the principal characteristics relevant to the

selection and application of programmable controllers and their associated peripherals;

Part 2 specifies equipment requirements and related tests for programmable controllers (PLC)

and their associated peripherals;

Part 3 defines, for each of the most commonly used programming languages, major fields of

application, syntactic and semantic rules, simple but complete basic sets of programming

elements, applicable tests and means by which manufacturers may expand or adapt those

basic sets to their own programmable controller implementations;

Part 4 gives general overview information and application guidelines of the standard for the

PLC end-user;

Part 5 defines the communication between programmable controllers and other electronic

systems;

Part 6 is reserved;

Part 7 defines the programming language for fuzzy control;

Part 8 gives guidelines for the application and implementation of the programming languages

defined in Part 3.

Scope

This Part of IEC 61131 applies to programmable controllers (PLC) and their associated peripherals

such as programming and debugging tools (PADTs), human-machine interfaces

(HMIs), etc., which have as their intended use the control and command of machines and

industrial processes.

PLCs and their associated peripherals are intended to be used in an industrial environment

and may be provided as open or enclosed equipment. If a PLC or its associated peripherals are

intended for use in other environments, then the specific requirements, standards and

installation practices for those other environments must be additionally applied to the PLC

and its associated peripherals.

The functionality of a programmable controller can be performed as well on a specific hardware

and software platform as on a general-purpose computer or a personal computer with industrial

environment features. This standard applies to any products performing the function of PLCs

and/or their associated peripherals. This standard does not deal with the functional safety or

other aspects of the overall automated system. PLCs, their application programme and their

associated peripherals are considered as components of a control system.

Since PLCs are component devices, safety considerations for the overall automated system

including installation and application are beyond the scope of this Part. However, PLC safety as

related to electric shock and fire hazards, electrical interference immunity and error detecting

of the PLC-system operation (such as the use of parity checking, self-testing diagnostics, etc.),

are addressed. Refer to IEC 60364 or applicable national/local regulations for electrical installation

and guidelines.

This Part of IEC 61131 gives the definitions of terms used in this standard. It identifies the

principal functional characteristics of programmable controller systems.

2 Normative references

The following referenced documents are indispensable for the application 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.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1

application programme or user programme

logical assembly of all the programming language elements and constructs necessary for the

intended signal processing required for the control of a machine or process by a PLC-system

3.2

automated system

control system beyond the scope of IEC 61131, in which PLC-systems are incorporated by or

for the user, but which also contains other components including their application programmes

3.3

field device

catalogued part to provide input and/or output interfaces or to provide data preprocessing/

post-processing to the programmable controller system. A remote field device may

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