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Mission 60 · Pro PLC programming exercise

Interlock every layer

Compute each carton's place from a pattern and build a stable pallet.

Stack 32 cartons, eight to a layer, four layers, each layer turned across the one below, then send the pallet out and start the next.

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The 3D palletiser this mission runs on Pro mission
Test replay

A whole interlocked pallet

Test 1 of 2
Set by the testChecked by the testStep 400 of 400 · 8.2 s
Level
Expert
Time
About 90 min
Reward
+1200 XP
Rig
3D palletiser
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
30. Machine lab 5: expert systems
Automatic tests

What the tests check

  1. Every carton goes to its computed place.
  2. Odd layers are turned crossways, so the layers .
  3. The head only travels at 1.6 m.
  4. Grip waits for GripOK; release waits for it to go.
  5. After 32 cartons the pallet goes out and the count starts again.
  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

Palletising patterns are configured, not hand-coded, on modern palletisers, but the arithmetic underneath is this, and someone has to commission it.

A column-stacked pallet looks fine leaving the factory and arrives as a heap. Travelling low knocks the stack over. Counting too early leaves a gap that the next layer falls into.

Where you'd find thisStack a pallet that will not fall over in the lorry

End-of-line palletisers build every pallet that leaves a factory. The controller computes each carton's place from a pattern, alternates the pattern layer by layer so the cartons interlock, and swaps pallets when one is full.

  1. InfeedCartons to the stop
  2. PickVacuum head
  3. PlacePattern positionYou are here
  4. Pallet out4 layers, then change
On a real site: places, parts and safety
  • Food and drink end-of-line packing
  • Distribution centres building mixed pallets
  • Building products, paper and chemicals in sacks

Palletiser cells are fully fenced; the pallet exit has a light curtain with muting so pallets can leave but people cannot enter.

A falling carton from 2 m can injure: the head never travels low over people or stacks.

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

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