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Mission 52 · Pro PLC programming exercise

Level, then open

Run a three-stop goods lift: calls, two speeds, doors and a safety edge.

Answer calls at three floors. Pick the next floor, run fast, slow down at its vane, stop at its levelling switch, open the doors for 4 s and close them. Never move unless the doors are closed.

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The 3D goods lift this mission runs on Pro mission
Test replay

To the top floor

Test 1 of 4
Set by the testChecked by the testStep 18 of 18 · 6 s
Level
Advanced
Time
About 50 min
Reward
+600 XP
Rig
3D goods lift
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
28. Machine lab 3: measurements and batches
Automatic tests

What the tests check

  1. Calls are remembered until answered, with their lamps.
  2. Fast until the target's vane, slow to its level switch, then stop.
  3. Floors in between are passed at full speed.
  4. Doors open 4 s, then close; the safety edge reopens them.
  5. The car never moves unless the doors are closed.
  1. Try it Use the buttons below the model and watch the rig respond.
  2. Test solution Every check runs on your code in one press.
  3. Replay If one fails, step through it one scan at a time to see why.
Why it matters

Where you’d see this on site

Goods lifts, platform lifts and service lifts run on small PLCs with exactly these rules, inside a separate hard-wired safety chain.

A car that stops fast misses the floor and becomes a trip hazard for a loaded pallet truck. Doors that open off-level or move while open are how people fall down shafts.

Where you'd find thisStop level, open only when level, never move with the doors open

Goods lifts move pallets between floors of warehouses, shops and factories. The controller remembers calls, chooses a direction, slows down on vanes before each floor and opens the doors only when the car is level.

  1. CallRemembered, lamp on
  2. TravelFast, then slowYou are here
  3. LevelStop at the switch
  4. DoorsOpen, wait, close
On a real site: places, parts and safety
  • Warehouses and distribution mezzanines
  • Shops, restaurants and hospital service lifts
  • Factories moving work between floors

Lifts are covered by EN 81-20: door locks, overspeed governors and buffers protect people whatever the controller does.

A safety edge on the door reverses it before it can crush a load or a hand.

The sizes, timings and cutaways are teaching choices, not a drawing of any one real installation.

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