Structured Text is not supported here.

This simulator is Ladder-only, and is no longer developed. studio.rungs.dev — the simulator I work on now — runs Structured Text and Ladder side by side against the same tags.

Structured Text (ST)

Structured Text is one of the five programming languages defined by IEC 61131-3. It is a high-level, text-based language similar to Pascal: instead of drawing rungs, you write assignments, conditionals, and loops.

IF Start AND NOT Stop THEN
    Motor := TRUE;
ELSIF Stop THEN
    Motor := FALSE;
END_IF;

Ladder Diagram suits relay-style interlocking and anyone coming from electrical schematics. Structured Text suits arithmetic, state machines, and anything that would take a dozen rungs to express.

Is Structured Text supported in PLC Simulator Online?

No. PLC Simulator Online only supports Ladder Diagram (LD), and the simulator is no longer in active development.

To write Structured Text in the browser, use studio.rungs.dev (opens in a new tab) — the simulator I work on now, which runs Structured Text and Ladder Logic side by side. Its Structured Text documentation (opens in a new tab) covers the syntax in full.

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