The timer that never finishes
A three-second start delay that only works if you hold the button.
Pump P-101 should start 3 seconds after a press of Start, so the outlet valve has time to open first. Fix the delay so a short press is enough. Stop cancels a start that is still waiting, and stops a running pump.
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Operator report: a short press of Start
Test 1 of 3StartInputOFFStopInputOFFPumpOnPump commandON- Level
- Easy · 10 points
- Kind
- Find the fault
- Time
- About 8 min
- Pass rate
- New
- Machine
- 3D pump skid
- Siemens
- LAD and SCL
- Rockwell
- Ladder and Structured Text
- Beckhoff
- Structured Text
I press Start and nothing happens. If I hold Start for a full three seconds the pump starts, but it stops the moment I let go.
What the checks test
- A short press of Start starts the pump 3 s later.
- PumpOn stays OFF during those 3 s.
- Stop cancels a start that is still waiting.
- Stop turns a running pump OFF.
The checks run 3 tests on the machine, scan by scan: Operator report: a short press of Start; Stop cancels a waiting start; Stop stops a running pump.
Where you’d find this
A pump on a cooling loop waits a few seconds after Start, so its outlet valve can open first.
A timer fed straight from a push button never finishes. The pump either never starts, or runs only for whoever holds the button.
How it should behave
- Start
- A press starts the pump 3 s later.
- Stop
- Cancels a waiting start; stops a running pump.
Press Run, then click Start once. Watch the timer count to 3 s, then the pump starts.
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