Overview
IEC TR 61131-8:2017 is an International Electrotechnical Commission (IEC) technical report providing essential guidelines for the application and implementation of programming languages for programmable controller systems, as defined in IEC 61131-3. This standard supports both users and implementers by offering best practices on programming methods, usage of language elements, and recommendations for programming and debugging tools (PADT). The document is part of the broader IEC 61131 series, which focuses on industrial-process measurement, control, and automation via programmable controllers.
This third edition introduces significant extensions from the previous version, addressing new data types, conversion functions, references, namespaces, and object-oriented programming features. While the focus is on the software aspect, aspects such as safety or electromagnetic compatibility are addressed in related standards like IEC 61131-4.
Key Topics
IEC TR 61131-8:2017 covers a wide range of critical topics for effective use and implementation of programming languages in industrial automation:
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Guidelines for IEC 61131-3 Application:
Offers actionable advice on programming programmable controllers, considering both distributed and stand-alone industrial control applications.
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Implementation Guidelines for IEC 61131-3 Languages:
Explains considerations and requirements for the robust implementation of the five standard programming languages:
- Ladder Diagram (LD)
- Function Block Diagram (FBD)
- Instruction List (IL)
- Structured Text (ST)
- Sequential Function Chart (SFC)
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Programming and Debugging Tool (PADT) Recommendations:
Describes recommended features and capabilities for tools that assist in programming, testing, and maintaining programmable controller systems.
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Data Types, Variables, and Function Blocks:
Outlines guidelines for efficient use of new data types, variable initialization, multi-element variables, bit-strings, and function block methodologies.
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Object-Oriented Features:
Details best practices for using object-oriented concepts such as classes, methods, inheritance, and interfaces within IEC 61131-3 languages.
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Task Scheduling and Execution:
Discusses approaches for cyclic, periodic, and event-driven program execution; addresses scheduling mechanisms to ensure deterministic operations in industrial environments.
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Deprecated Practices and Error Handling:
Identifies obsolete programming practices and recommends better alternatives, along with guidance for error handling and compliance considerations.
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Namespace and Modularization:
Encourages the use of namespaces and modular programming to enhance clarity and maintainability in complex control systems.
Applications
The guidelines provided by IEC TR 61131-8:2017 are invaluable in a wide range of industrial-process automation settings, including:
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Manufacturing Automation:
Assists engineers in creating flexible, maintainable, and scalable programs for programmable logic controllers (PLCs) in factory environments.
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Process Control Systems:
Ensures consistent implementation of control strategies in processes needing high reliability, such as chemical plants or power generation.
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Distributed Control Systems:
Aids in designing modular solutions where control tasks are handled by geographically distributed programmable controllers communicating over industrial networks.
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PADT Development:
Informs developers and vendors in building or enhancing programming and debugging tools tailored for the needs of industrial control system integrators and maintenance teams.
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Training and Best Practices:
Provides a reference for training operators, automation engineers, and software developers on correct programming strategies and use of IEC 61131-3 languages.
Related Standards
For a comprehensive approach to industrial programmable controller systems, consider these related IEC standards:
- IEC 61131-3: Programmable controllers - Part 3: Programming languages (core reference for programming language definitions and constructs)
- IEC 61131-4: Programmable controllers - Part 4: User guidelines (covers additional aspects such as EMC and functional safety)
- IEC 61131-5: Programmable controllers - Part 5: Communications
- IEC 61508: Functional safety of electrical/electronic/programmable systems
- ISO/IEC 9506: Manufacturing Message Specification (MMS) for communications
Adhering to IEC TR 61131-8:2017 fosters more robust, reliable, and maintainable automation systems-driving efficiency, safety, and integration in industrial-process measurement and control.