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Mission 29 · Pro PLC troubleshooting exercise

The Faulty Filling Station

Find why bottles overflow, then fix it.

This station keeps filling past the target. Fix the code. Open FillValve only when a bottle is present, Volume is below 80%, Permit is ON and Fault is OFF. Run ConveyorOn only when no bottle is at the nozzle or the bottle has reached 80%. The conveyor also needs Permit ON and Fault OFF. Volume is how full this 1 L (1,000 mL) bottle is: 80% = 800 mL.

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The 3D filling line this mission runs on Pro mission
Test replay

Valve opens for a bottle below 80%

Test 1 of 6
Set by the testChecked by the testStep 1 of 1 · 20 ms
Level
Advanced
Time
About 18 min
Reward
+300 XP
Rig
3D filling line
Siemens editors
SCL
Rockwell editors
Structured Text
Course stage
15. Prove a safe recovery
Automatic tests

What the tests check

  1. No bottle means no filling.
  2. At 80% FillValve closes.
  3. Losing Permit, or Fault coming ON, stops both FillValve and ConveyorOn.
  4. A full bottle moves on: ConveyorOn turns ON.
  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

A drinks line stops each bottle under a nozzle, fills it, then sends it on. Sometimes bottles jam on the belt.

Filling during a jam can spill drink onto the line. Moving a bottle on too early leaves it short. In this exercise, 80% of a 1 L bottle is 800 mL.

Where you'd find thisPutting drinks into bottles

At a soft-drinks factory, empty bottles arrive on a moving belt. A sensor tells the controller when a bottle is under the filling nozzle. The valve opens, fills the bottle, then closes before the belt moves again. Caps and labels go on before the bottles are packed.

  1. Empty bottlesThe belt brings them to the nozzle
  2. Fill each bottleStop it, fill it, then let it moveYou are here
  3. Add caps and labelsSeal the drink and name the product
  4. Pack the bottlesPut finished bottles into boxes
On a real site: places, parts and safety
  • Soft-drinks factory — filling bottles without spills
  • Dairy — putting milk into bottles
  • Cleaning-products factory — measuring liquid into containers
  • Food packaging line — counting bottles before packing

If the filling valve opens without a bottle under it, liquid spills onto the belt. If the line jams, the valve must not keep filling.

Real conveyors need guards. The power must be safely locked off before anyone clears a blockage. The Stop input here is not an emergency stop.

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

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