Control Expert is unusually generous: it speaks all five IEC 61131-3 languages — Ladder, Function Block, Structured Text, Instruction List — plus SFC (Grafcet), the sequential language Schneider helped pioneer. Here's the same motor seal-in in every one, live. Flip the inputs and watch the current flow through all five.
The logic: press Start, the motor runs and seals in; press Stop, it drops. Switch tabs to see it as Ladder, FBD, Structured Text, Instruction List and SFC — the inputs below drive all five identically, because they compile to the same logic.
Motor := (Start OR Motor) AND NOT Stop; // reads like the sentence: run if Start // or already-running, unless Stop is pressed
LD Start OR Motor ANDN Stop ST Motor // the same logic as raw stack instructions — // the assembly language of PLCs (legacy)
Tap Start on then off — the motor stays running (it seals itself in). The SFC view tells the same story as a sequence: S1 Idle → (Start) → S2 Run → (Stop) → back. That step-and-transition view is why Schneider engineers reach for SFC on any machine that's really a recipe of stages.
Tap each.
A bottling machine runs as a strict sequence: fill → wait → cap → wait → eject, with clear conditions to move between stages. Which language documents and runs it best?