PLC Scan Cycle: How Logic Executes | Lesson 5 | PLC Fundamentals
Before you write your first line of code, you must understand the "Heartbeat" of the controller: The Scan Cycle. Unlike a standard computer that executes instructions linearly, a PLC operates within a specific, high-speed framework designed for industrial reliability.
In this lesson, we break down exactly how the PLC processes data, why the order of your rungs matters, and how "Scan Time" can make or break your automation project. Mastering this cycle is what separates a hobbyist from a professional programmer.
🔄 What You Will Master:
The 3-Step Execution Process: A deep dive into the Read-Execute-Write sequence that happens thousands of times per second.
Understanding the PLC Cycle: Why the CPU takes a "snapshot" of inputs before running your logic and why that matters for your program's behavior.
Cycle Types: We explore different execution models, including cyclic tasks, periodic interrupts, and event-driven execution.
Scan Time Secrets: Learn what Scan Time is, how to measure it, and why a "Watchdog Timer" error is something you always want to avoid.
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