E-stop wins, every time
Stop at once, stay stopped, reset on purpose.
Start and Stop already work. Add the emergency stop. EStopOK is ON while the E-stop circuit is healthy and turns OFF when someone hits the E-stop. Stop the pump at once and the trip, shown on EStopLamp. Reset clears the trip, but only once the E-stop has been pulled out again. After a reset the pump stays off until Start.
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The E-stop stops the pump at once and latches
Test 1 of 4StartInputOFFEStopOKE-stop circuit healthyONPumpOnPump commandOFFEStopLampReset neededON- Level
- Easy · 10 points
- Kind
- Make it safe
- Time
- About 10 min
- Pass rate
- New
- Machine
- 3D pump skid
- Siemens
- LAD and SCL
- Rockwell
- Ladder and Structured Text
- Beckhoff
- Structured Text
What the checks test
- EStopOK OFF turns PumpOn OFF on the same and lights EStopLamp.
- Pulling the E-stop out (EStopOK ON) does not clear the trip.
- Reset clears the trip only while EStopOK is ON.
- Start does nothing while the trip is latched.
- After a reset the pump stays off until Start is pressed.
The checks run 4 tests on the machine, scan by scan: The E-stop stops the pump at once and latches; Reset needs the E-stop pulled out first; No restart without a fresh Start; Start does nothing with the E-stop pressed.
These challenges teach the logic. On a real machine, safety functions run on a safety-rated PLC, such as a Siemens F-CPU or a Rockwell GuardLogix, and are designed to ISO 13849.
Where you’d find this
Every machine you can stand next to has an emergency stop. Pumps, conveyors and presses all follow the same rules.
Releasing an E-stop must never restart a machine. The person who pressed it may still be in the way.
How it should behave
- E-stop
- EStopOK OFF: pump off at once, trip latched.
- Reset
- Clears the trip once EStopOK is back ON.
- Restart
- Only a fresh Start after the reset.
Press Run and Start. Switch EStopOK OFF: the pump stops. Switch it ON: still stopped. Press Reset, then Start.
More challenges
- 17A broken wire must stop itNormally closed stop and overload contacts, the safe way round.Easy · Make it safe
18Close the guard, stay stoppedOpening the guard stops the belt. Closing it does not start it.Easy · Make it safe- 19Never let the pump run dryTwo seconds without water trips it. A splash does not.Medium · Make it safe
20Trip before it overflowsAn independent high-high switch that works when the transmitter doesn’t.Medium · Make it safe