https://jskinner.info/tags/industrial-automation/ Recent content in Industrial-Automation on Jonathan Skinner https://jskinner.info/media/image https://jskinner.info/media/image Hugo -- 0.150.0 en-us Mon, 08 Sep 2025 00:00:00 +0000 https://jskinner.info/posts/predictable-plc-state-machines/ Mon, 08 Sep 2025 00:00:00 +0000 https://jskinner.info/posts/predictable-plc-state-machines/ <p>Modern PLC projects suffer when control logic is scattered across rungs, hidden in timer branches, or tightly coupled to raw I/O. The result is brittle behavior, difficult commissioning, and painful offline testing. The approach below is a simple, repeatable pattern for building state-driven modules that stay deterministic, testable, and vendor‑friendly. It divides each routine into clear sections—<strong>Inputs → Commands → Interlocks → Permissives → State &amp; Transitions → Status → Control Resources → Outputs</strong>—and enforces one rule above all: <strong>states govern state; device control happens only in Outputs</strong>. Whether you write in ST or Ladder, this structure keeps behavior predictable and easy to review.</p>