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Mission 39 · Pro Drives exercise

Run a pump on a drive

Send a run command and a speed, then wait for the drive to prove it.

P-101 runs on a variable speed drive. Start latches DriveRun ON and Stop turns it OFF; Stop wins. Send SpeedRef, the speed in %, from the operator’s SpeedSetpoint, kept between 30% and 100%. The drive ramps up and down at its own rate. Turn PumpReady ON only while DriveRun is ON and the drive reports DriveRunning and DriveAtSpeed.

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

Start, ramp, then ready

Test 1 of 4
Set by the testChecked by the testStep 5 of 5 · 3.3 s
Level
Applied
Time
About 20 min
Reward
+300 XP
Rig
3D pump skid
Siemens editors
SCL, LAD, FBD
Rockwell editors
Structured Text, Ladder, FBD
Course stage
24. Run a pump on a drive
Automatic tests

What the tests check

  1. Start latches DriveRun. Stop turns it OFF, even with Start held.
  2. SpeedRef follows SpeedSetpoint, but never below 30% or above 100%.
  3. PumpReady stays OFF while the drive ramps, and comes ON once it is at speed.
  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 water pump runs on a variable speed drive. The operator sets a speed, and the next step waits until the pump gets there.

Acting on the command alone opens valves and starts timers while the pump is still speeding up. The drive's feedback is the proof.

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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