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Structuring with SFC
do's & don'ts
V1.0 Official Release


PLCopen Safety
Part 1
Version 2.0 now released


Information Model
V1.01.09 RfC


PLCopen starts
new working group
on Industry 4.0










TC1 - Standards

The PLCopen Technical Committee 1, TC1, deals with Standards. The main focus of this activity is upon the IEC 61131-3 standard, as developed by the International Electrotechnical Committee. Since IEC holds the copyright, there are no downloadable versions of it available.
IEC 61131-3 provides the basis for PLCopen. This standard is part of the International Standard IEC 61131, providing a complete collection of standards on programmable controllers and their associated peripherals. Click here for more information on peripherals. It consists of the following parts:

IEC 61131-1 General information

establishes the definitions and identify the principal characteristics relevant to the selection and application of programmable controllers and their associated peripherals. Current version is 2.0 from 2003. The IEC 61131-1 overview and table of content.

IEC 61131-2 Equipment requirements and tests

specifies equipment requirements and related tests for programmable controllers (PLC) and their associated peripherals. Current version is 3.0 from 2007. The IEC 61131-2 overview and table of content.

IEC 61131-3 Programming Languages - providing the basis for PLCopen

The third part defines, as a minimum set, the basic programming elements, syntactic and semantic rules for the most commonly used programming languages. This includes the graphical languages Ladder Diagram and Functional Block Diagram, and the textual languages Instruction List and Structured Text, as well as means by which manufacturers may expand or adapt those basic sets to their own programmable controller implementations. This website is mostly dedicated to IEC 61131-3, and contains a lot of information on it.
The IEC 61131-3 overview and table of content.
The PLCopen introduction on IEC.
Evaluation of software. The current version is 3.0 from 2013.

IEC 61131-4 User Guidelines

A technical report providing general overview information and application guidelines of the standard for the end user of programmable controllers. Current version is 2.0 from 2004. The IEC 61131-4 overview and table of content.

IEC 61131-5 Messaging service specification

defines the data communication between programmable controllers and other electronic systems using the Manufacturing Message Specification (MMS), according to International Standard ISO/IEC 9506. Current version is 1.0 from 2000. The IEC 61131-5 overview and table of content, and  the PLCopen introduction on 61131-5.

IEC 61131-6 Functional Safety

This Part of the IEC 61131 series specifies requirements for programmable controllers (PLCs) and their associated peripherals, as defined in Part 1, which are intended to be used as the logic subsystem of an electrical/electronic/programmable electronic (E/E/PE) safety-related system. Current version is 1.0 from 2012. The IEC 61131-6 overview and the table of content.

IEC 61131-7 Fuzzy control programming

defines basic programming elements for fuzzy logic control as used in programmable controllers. Te current version is 1.0 from 2000. For the PLCopen introduction on IEC 61131-7.

IEC 61131-8 Guidelines for the application and implementation of programming languages

The Technical Report (TR) provides a software developers guide for the programming languages defined in part 3. The current version is 2003.
IEC 61131-8 overview and table of content.

IEC 61131-9 Single-drop digital communication interface for small sensors and actuators (SDCI)

This standard is also known as “IO-Link” (Currently CDIS - Committee Draft IS) and is coupled to a communication interface. Current version is Committee Draft International Standard.

IEC 61131-3 : providing the basis

The PLCopen activities are based upon the IEC 61131-3 standard, the only global standard for industrial control programming. It harmonizes the way people design and operate industrial controls by standardizing the programming interface. A standard programming interface allows people with different backgrounds and skills to create different elements of a program during different stages of the software lifecycle: specification, design, implementation, testing, installation and maintenance. Yet all pieces adhere to a common structure and work together harmoniously. The standard includes the definition of the Sequential Function Chart (SFC) language, used to structure the internal organization of a program, and four inter-operable programming languages: Instruction List (IL), Ladder Diagram (LD), Function Block Diagram (FBD) and Structured Text (ST). Via decomposition into logical elements, modularization and modern software techniques, each program is structured, increasing its re-usability, reducing errors and increasing programming and user efficiency.