Finish the purge
Keep the pump running 200 ms after release.
Turn PumpOn ON as soon as Start is pressed. When Start is released, keep PumpOn ON for 200 ms more, then turn it OFF. That extra run flushes (purges) the last liquid from the pipe. Use an , which waits a set time before switching OFF.
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Pump runs 200 ms more after release
Test 1 of 3StartStart requestOFFPumpOnPump commandOFF- Level
- Foundation
- Time
- About 8 min
- Reward
- +100 XP
- Rig
- 3D pump skid
- Siemens editors
- SCL, LAD
- Rockwell editors
- Structured Text, Ladder
- Course stage
- 4. Wait, then act
What the tests check
- PumpOn turns ON straight away when Start is pressed.
- PumpOn stays ON for 200 ms after Start is released.
- PumpOn turns OFF when the 200 ms are up.
- Try it Use the buttons below the model and watch the rig respond.
- Test solution Every check runs on your code in one press.
- Replay If one fails, step through it one scan at a time to see why.
Where you’d see this on site
At a drinks factory, a pump flushes leftover drink out of a pipe. It keeps running for a moment after the wash request ends.
Stopping too soon leaves liquid in the pipe. Running forever wastes wash water and delays the next batch.
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.
- Street mainsWater enters the building
- Storage tankHolds a supply for the pumps
- Water pumpsPush water to the floors aboveYou are here
- 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.
Next in the course
10Count the arrivalsCount each bottle once. Stop at three.Foundation · 8 min · +100 XP- 11Count with a one-shotOne bottle covers the sensor for many scans. Count it once.Applied · 18 min · +250 XP
- 12Count bottles as they leaveCount each bottle as it clears the sensor, not as it arrives.Applied · 10 min · +150 XP
- 13It never reaches threeSomething keeps clearing the count. Find it.Applied · 12 min · +200 XP