Programmers and getting started in PLC automation and control programming (Podcast 14) скачать в хорошем качестве

Programmers and getting started in PLC automation and control programming (Podcast 14)

Flowcharts and PLC programming go hand-in-hand — especially in industrial automation projects like the onessupplied by i4 Automation. Why Use Flowcharts in PLC Programming? A flowchart is a visual representation of the control logic before you write code. For PLC projects, flowcharts help you: • Clarify the machine's sequence of operation • Reduce commissioning time • Avoid logic conflicts • Communicate clearly with customers and electricians • Simplify documentation for CE/UKCA compliance They’re especially useful for: • Sequential machines • Multi-stage processes • Fault handling logic • Alarm management Flowcharts vs PLC Programming Languages Most PLCs (including platforms like Unitronics) are based on IEC 61131-3 languages: • Ladder Logic (LD) – Electrical-style logic • Function Block Diagram (FBD) – Block-based logic • Structured Text (ST) – High-level text programming • Sequential Function Chart (SFC) – Flowchart-style sequencing 👉 Flowcharts most closely resemble Sequential Function Charts (SFC). Example: Simple Machine Start Sequence Flowchart Logic 1. Start button pressed 2. Check the safety circuit OK 3. Start motor 4. Wait 5 seconds 5. Enable conveyor 6. Monitor fault condition 7. Stop if fault How That Becomes PLC Logic In Ladder Logic: • Start latch • Safety interlock contacts • Timer block (TON) • Output coils • Fault reset rung When to Use Flowcharts (Best Practice) Flowcharts are most valuable when: ✔ Designing new machinery ✔ Upgrading legacy relay systems ✔ Working with OEM clients ✔ Training junior engineers ✔ Documenting process sequences For smaller logic (simple pump control, level switching, etc.), they’re often unnecessary. Practical Workflow (Professional Method) Here’s a structured approach many experienced automation engineers use: 1. Define I/O list 2. Write a sequence of operations 3. Draw a flowchart 4. Convert to SFC or Ladder 5. Simulate 6. Commission on site 7. Add fault handling refinement Key Takeaway Flowcharts are not programming — they are thinking tools. The better the flowchart: • The cleaner the PLC code • The faster the commissioning • The fewer the late-night callouts