Practice missions
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Practice missions
Mission 01 · Free PLC scan cycle exercise

Your first command

Make a pump follow a button.

Make the pump run while you hold Start, and stop when you let go. Your code switches the pump through PumpOn. PumpOn is a : a named signal that is ON or OFF.

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The 3D pump skid this mission runs on
Test replay

Pump runs while Start is held

Test 1 of 3
Set by the testChecked by the testStep 1 of 1 · 20 ms
Level
Foundation
Time
About 8 min
Reward
+100 XP
Rig
3D pump skid
Siemens editors
SCL, LAD
Rockwell editors
Structured Text, Ladder
Course stage
1. Read, decide, command
Automatic tests

What the tests check

  1. While Start is held, PumpOn is ON ().
  2. When you let go of Start, PumpOn goes OFF ().
  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

In a factory wash room, an operator holds a button to run a water pump. Letting go should stop the pump.

If the pump keeps running after the button is released, the hose keeps spraying when nobody expects it.

Where you'd find thisWater for the top floors

In a block of flats, a basement tank holds water from the mains. Two pumps push it up to the taps above. One runs while the other waits as a spare. A low-water switch stops the pumps before the tank runs dry.

  1. Street mainsWater enters the building
  2. Storage tankHolds a supply for the pumps
  3. Water pumpsPush water to the floors aboveYou are here
  4. Taps upstairsResidents use the water they need
On a real site: places, parts and safety
  • Block of flats — pushing water up to the top floors
  • Brewery — sending hot water to a brewing tank
  • Water-treatment works — moving water between filter tanks
  • Office building — pumping water round the heating pipes

A low-water switch can take away permission to run. The pump must stop before it runs dry and damages its seal.

The PLC can say ON even when a pump has failed. Check the measured flow as well as the command.

The Stop input in these exercises is not an emergency stop. Real machines also need guards, emergency stops and a safe way to cut the power.

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

Keep going

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