1.1 Scope and object

This Part of IEC 61131 specifies requirements and related tests for programmable controllers (PLC) and their associated peripherals (for example, 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.

This standard also applies to any products performing the function of PLCs and/or their associated peripherals.

Equipment covered in this standard is intended for use in overvoltage category II (IEC 60664-1) in low-voltage installations, where the rated mains supply voltage does not exceed a.c. 1 000 V r.m.s. (50/60 Hz), or d.c. 1 500 V. (If PLCs or their associated peripherals are applied in overvoltage category III installations, then additional analysis will be required to determine the suitability of the equipment for those applications.)

1.1DV Modification to Paragraph 4 of 1.1:

Equipment operating at more than 600 V is considered as high voltage equipment with respect to the requirements in the National Electrical Code.

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 standard. 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.

The object of this standard is

- to establish the definitions and identify the principal characteristics relevant to the selection and application of PLCs and their associated peripherals;

- to specify the minimum requirements for functional, electrical, mechanical, environmental and construction characteristics, service conditions, safety, EMC, user programming and tests applicable to PLCs and the associated peripherals.

This Part also specifies

a)    service, storage and transportation requirements for PLCs and their associated peripherals (Clause 4);

b)    functional requirements for PLCs and their associated peripherals (Clause 5);

c)    EMC requirements for PLCs and their associated peripherals (Clause 8);

d)    safety requirements for PLCs and their associated peripherals (Clause 11);

e)    information that the manufacturer is required to supply (Clauses 7, 10 and 14);

f)    test methods and procedures that are to be used for the verification of compliance of PLCs and their associated peripherals with the requirements (Clauses 6, 9, and 12).

The tests are type tests or production routine tests, and not tests related to the ways PLC systems are applied.

1.101DV Addition of the following to 1.1:

This equipment is intended for installation in accordance with the National Electrical Code (NEC) for use in ordinary locations. Requirements based on the NEC are found in Annex dva of this document.

Summary of Topics

This revision of ANSI/UL 61131-2 dated June 10, 2021 is being issued to update the title page to reflect the most recent designation as a Reaffirmed American National Standard (ANS). No technical changes have been made.