Overview
IEC TR 61131-4:2004 is a Technical Report from the International Electrotechnical Commission that provides user guidelines for Programmable Logic Controllers (PLCs). Intended primarily for PLC end-users, it introduces the IEC 61131 series and helps users select, specify and apply PLC equipment in line with the IEC 61131 family. This second edition (2004) collates practical guidance on installation, safety, conformity and programming practice without redefining normative product requirements.
Key topics
- Scope and purpose
- Guidance to end-users on selecting and specifying PLCs according to the IEC 61131 series.
- Installation and site considerations
- Environmental conditions, field wiring and earthing recommendations.
- Electromagnetic compatibility (EMC) installation rules and immunity zones.
- Functional safety
- How to use PLCs in safety-related systems (SRS), integration strategies and requirements.
- Guidance on safety integrity levels (SIL) in demand and continuous modes and how PLCs contribute to risk reduction.
- Conformity and certification
- Overview of conformity, declarations of conformity, CE-marking considerations and transitional/regulatory aspects across jurisdictions.
- Programming and software guidance
- Practical advice on using IEC 61131-3 languages and examples: Ladder Diagram (LD), Function Block Diagram (FBD), Structured Text (ST), Instruction List (IL) and Sequential Function Chart (SFC).
- Use of user-defined function blocks (DFBs), program structure and language implementation tips.
- Informative annexes
- Annex A: Overviews of IEC 61131 parts (1, 2, 3, 5, 7).
- Annex B: Conformity, CE-marking and certification guidance.
- Annex C: Programming examples, structure and best practices.
Applications and practical value
- Helps engineers, maintenance teams and procurement specialists make informed PLC selection decisions that meet operational, safety and regulatory needs.
- Provides installers and integrators with practical installation and EMC guidelines to improve reliability.
- Assists safety engineers in integrating PLCs into safety-related systems, aligning PLC use with functional safety approaches and SIL considerations.
- Supports software developers and control engineers with real-world programming examples and architecture recommendations to increase maintainability and reuse.
Who should use this report
- Plant engineers, automation specialists, safety engineers, procurement officers and system integrators responsible for PLC selection, installation, certification and programming.
Related standards
- IEC 61131 series (particularly IEC 61131-1, -2, -3), plus parts addressing communication, safety and supplementary topics referenced in Annex A.
Keywords: IEC TR 61131-4, PLC user guidelines, IEC 61131 series, programmable controller, PLC selection, functional safety, EMC, PLC programming (LD, FBD, ST, IL, SFC), CE-marking, conformity.