Challenges
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Practice · 20 challenges

PLC programming challenges

Short problems on working 3D machines. Write the logic, find the fault or make a machine safe, in ladder or Structured Text, for Siemens or Rockwell. Automatic checks say pass or fail.

Challenges
20
Free
9
Editors
Ladder + text
New
Every day

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Kind
Level
Plan
Show
  1. 01One button, start and stopEach press of one button changes the pump over.Code itEasyNewFree
  2. 02Flash the warning lampOne second on, one second off, while the pump is tripped.Code itEasyNewFree
  3. 03Pump down between two floatsStart at the high float, stop below the low float.Code itEasyNewFree
  4. 04Sound the horn before it movesThree seconds of warning before the belt starts.Code itMediumNew Pro
  5. 05Pack six, then pauseCount six bottles, stop for the pusher, then go again.Code itMediumNew Pro
  6. 06The output that won’t listenStart does nothing. Jog works. Find out why.Find the faultEasyNewFree
  7. 07The timer that never finishesA three-second start delay that only works if you hold the button.Find the faultEasyNewFree
  8. 08Overflows by a dropFill to 80%. At exactly 80%, the valve stays open.Find the faultEasyNewFree
  9. 09The alarm you can’t clearAfter the storm, Reset does nothing. During it, Reset worked.Find the faultMediumNew Pro
  10. 10One scan too lateThe pump command outlives a trip by one scan.Find the faultMediumNew Pro
  11. 11The spare that keeps stealing the runAlternation, break-before-make and a failed recovery — together.Find the faultHardNew Pro
  12. 12Which fault actually happened first?A feedback timeout, first-out capture and a stuck Ack button.Find the faultHardNew Pro
  13. 13The bottle that was counted twiceRecover the right phase without counting a half-filled bottle.Find the faultHardNew Pro
  14. 14The transfer that flooded the wash roomTwo levels, actuator feedback, a coasting motor and a latched trip.Find the faultHardNew Pro
  15. 15The soak that never really happenedTemperature memory, a continuous soak and separate coolant flow.Find the faultHardNew Pro
  16. 16E-stop wins, every timeStop at once, stay stopped, reset on purpose.Make it safeEasyNewFree
  17. 17A broken wire must stop itNormally closed stop and overload contacts, the safe way round.Make it safeEasyNewFree
  18. 18Close the guard, stay stoppedOpening the guard stops the belt. Closing it does not start it.Make it safeEasyNewFree
  19. 19Never let the pump run dryTwo seconds without water trips it. A splash does not.Make it safeMediumNew Pro
  20. 20Trip before it overflowsAn independent high-high switch that works when the transmitter doesn’t.Make it safeMediumNew Pro
Three kinds

Code it, find the fault, make it safe

Code it

Write the logic from a short brief.

5 challenges
Find the fault

The code is broken and an operator has said what they saw. Fix it.

10 challenges
Make it safe

Add the logic a real machine needs to fail safely.

5 challenges

These challenges teach the logic. On a real machine, safety functions run on a safety-rated PLC, such as a Siemens F-CPU or a Rockwell GuardLogix, and are designed to ISO 13849.

Easy is worth 10 points, Medium 20 and Hard 40. Each challenge scores once, and the points count towards your XP too.

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