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Mission 25 · Pro SFC action qualifier exercise

What stays on?

A stored output stays ON until you reset it.

Start moves to the Set pump step, which stores PumpOn, so it stays ON. A transition then moves straight on to Retained command. PumpOn stays ON there with no action of its own. Stop moves to Reset pump, which resets PumpOn and stores Done.

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The 3D pump skid this mission runs on Pro mission
Test replay

PumpOn stays ON until Stop resets it

Test 1 of 2
Set by the testChecked by the testStep 3 of 3 · 260 ms
Level
Advanced
Time
About 18 min
Reward
+300 XP
Rig
3D pump skid
Siemens editors
GRAPH
Rockwell editors
SFC
Course stage
14. Give commands an end
Automatic tests

What the tests check

  1. PumpOn stays ON after the chart leaves Set pump.
  2. Stop reaches Reset pump, which turns PumpOn OFF.
  3. Done turns ON to show the cycle is finished.
  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

At a blending tank, a pump must keep running across several steps. The sequence stores its run command while the steps change.

A stored command does not switch off just because the sequence moves on. Without a clear reset, the pump can keep filling and overflow the tank.

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.

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