Studio 5000 · Track 04 · the Logix languages

One Circuit, Four Languages

Ladder rules the Logix world — it grew up replacing relay panels for American discrete machines — but Logix Designer also speaks FBD, Structured Text and SFC. (No Instruction List here; Rockwell never adopted it.) Here's the same motor seal-in in all four, live. Flip the inputs and watch every view light up together.

🪜 LD🔲 FBD⌨️ ST🔢 SFC
01 · The Rosetta Stone

Start · seal-in · stop

Press Start → the motor runs and seals in; press Stop → it drops. Switch tabs to see Ladder, FBD, Structured Text and SFC — the inputs below drive all four identically.

⊣ ⊢
Start
⊣/⊢
Stop
( )
Motor
⊣ ⊢
Motor (OTE seal-in)
Start
Motor
Stop
≥1
OR
&
AND
Motor
Motor := (Start OR Motor) AND NOT Stop;
// Logix ST — Pascal-like, great for math & loops
Step Idle
Motor OFF · wait Start
Start
Step Run
Motor ON · until Stop
Stop
▶ Start
⛔ Stop
Motor: OFF
⚙️

In Logix you pick a language per routine — a ladder routine for interlocks, an ST routine for math, all inside the same program. Most Rockwell shops live in ladder and reach for ST when the numbers get serious.

02 · Check yourself

Which routine language?

You need to average 64 analog samples in a FOR loop with array indexing. Best routine language?