The SFC jumped to Step 99. The crane rose. The drain opened.
Crane_Up := TRUE; Acid_Drain_Valve := TRUE; // SD qualifier keeps this ON Emergency_Alerter := TRUE; Inside Step 0 's Entry Action: codesys sfc example
She went to the Action Definition for Step 20. Instead of putting Drain_Valve := FALSE in the step's exit action, she created a Global Action called Acid_Safety and set its qualifier to SD (Set Dominant—stays TRUE until explicitly reset). The SFC jumped to Step 99
But then... nothing.