Introduction:

As automation systems become more complex and safety-critical, both international standards and local regulations are evolving to match. Engineers working with PLCs must now go beyond basic logic design — they need to be fluent in the latest IEC standards and understand how modern safety regulations influence their systems.

1. A Quick Overview of Key IEC Standards

🔹 IEC 61131-3: The Core of PLC Programming

This standard defines:

• Programming languages: Ladder Logic (LD), Structured Text (ST), Function Block Diagram (FBD), etc.
• Data types, structures, and modular programming concepts

💡 Update: The recent versions of IEC 61131-3 encourage object-oriented programming, making it easier to write reusable, scalable PLC code.

🔹 IEC 61508 / IEC 62061: Functional Safety

Focuses on:

• Designing systems that fail safely
• Establishing Safety Integrity Levels (SIL)
• Creating redundancy, diagnostics, and safe shutdown procedures

2. Why These Standards Matter Today

• More factories are moving toward Industry 4.0 and remote diagnostics
• Systems must now comply with safety regulations before commissioning
• Programmers must consider software and hardware-level protection

3. How New Safety Regulations Influence Design

Modern safety standards require:

• Certified safety PLCs and I/O modules
• Use of dedicated safety networks (e.g., PROFIsafe, Safety over EtherCAT)
• Implementation of emergency stop circuits, safety relays, light curtains, and interlocks tied directly to the PLC logic

🛑 Example: You can’t just “add an E-Stop.” It must comply with SIL/PL requirements, have diagnostic coverage, and possibly dual-channel inputs.

4. What This Means for You (as an Engineer)

You’ll need to:

✅ Choose hardware that is certified for functional safety
✅ Program with clear separation between standard and safety logic
✅ Perform risk assessments as part of your design process
✅ Document your logic to support compliance audits

5. Practical Tips Moving Forward

• Stay updated on IEC revisions and regional adoption (e.g., EU vs Africa vs USA)
• Embrace modular, reusable code (as encouraged by IEC 61131-3)
• Explore safety simulation tools or test benches to validate your logic
• Keep training — many automation vendors now offer IEC + safety certification courses

Conclusion

PLC programming is no longer just about “if-this-then-that.” It’s now about writing smart, safe, and compliant code in line with evolving international standards. Staying ahead of these changes doesn’t just protect your system — it protects your career.