The transition to Step 0 required Acid_Level < 5% . But the drain valve closed after 2 seconds because the "DIP" step's action had been deactivated. She forgot: Actions in SFC only run while their step is active.
The SFC was in with a coil halfway submerged.
Lena shook her head. "No. We need an SFC." She opened CODESYS and created a new POU (Program Organization Unit). She chose Sequential Function Chart (SFC) . No ladder. No structured text loops. Just pure, visual, time-tested sequence logic. codesys sfc example
She slammed her fist on the desk.
Crane_Up := TRUE; Acid_Drain_Valve := TRUE; // SD qualifier keeps this ON Emergency_Alerter := TRUE; Inside Step 0 's Entry Action: The transition to Step 0 required Acid_Level < 5%
This is how industrial programmers think. Not just "code that runs"—but .
The SFC's showed:
The SFC jumped to Step 99. The crane rose. The drain opened.