Practice missions
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Practice missions
Mission 03 · Free PLC permissive exercise

Bring the tank up to temperature

Heat the water, then stop at 45°C.

Heat and stir the water while Start is held and Permit is ON: turn HeaterOn and MixerOn ON. At 45°C, turn HeaterOn OFF; MixerOn can keep turning. If Level is below 10 or Stop is pressed, turn both OFF. Level is a percentage of this 100 L tank, so 10% means 10 litres.

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The 3D process tank this mission runs on
Test replay

Heats to 45°C, mixer keeps going, Stop ends both

Test 1 of 3
Set by the testChecked by the testStep 5 of 5 · 100 ms
Level
Foundation
Time
About 18 min
Reward
+300 XP
Rig
3D process tank
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
2. Only run when allowed
Automatic tests

What the tests check

  1. Heater and mixer run only with Start held, Permit ON, Stop not pressed and Level at 10% or more.
  2. At 45°C the heater turns OFF. The mixer can keep turning.
  3. Losing Permit, Level falling below 10% or pressing Stop turns both OFF at once.
  4. Watch the heater power (kW), the temperature and the warming rate (°C/min) as the water heats up.
  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 brewery heats water in a tank before washing its equipment. The heater should only run while enough water covers it.

A heater that is not covered can overheat and damage the tank. Heating past the target also wastes energy.

Where you'd find thisMaking one batch of drink

At a drinks factory, valves let measured amounts of water and syrup into a mixing tank. An electric mixer blends them into one batch. An outlet valve then sends the drink to a holding tank. Filling machines bottle it from there.

  1. Ingredient tanksHold the water and syrup
  2. Mixing tankFill, mix and measure one batchYou are here
  3. Holding tankKeeps the finished drink ready
  4. Bottle fillerPuts the drink into bottles
On a real site: places, parts and safety
  • Drinks factory — blending water and syrup
  • Paint factory — mixing ingredients into a consistent colour
  • Water-treatment works — preparing a measured chemical mixture
  • Brewery — heating water for washing equipment

A full tank does not close its own inlet. Water keeps arriving until the valve closes, so an open inlet can flood the room.

A heater that is not covered by liquid can overheat. Real tanks have separate safety devices as well as the PLC programme.

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

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