Fix 02 — STOP is ignored
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Briefing
STOP does nothing. Find out why. START runs the motor and it holds itself on, but pressing STOP changes nothing. Look at what the program uses: STOP is declared, yet no rung reads it. Fix the program so STOP stops the motor, and a new START runs it again.
Objectives
- START runs MOTOR and it keeps running after release
- STOP stops MOTOR
- After a stop, START runs MOTOR again
Hints
- Press STOP while the motor runs and watch MOTOR. Then look for STOP in the program: does any rung read it?
- Once the motor holds itself on, START is no longer needed to keep it running. Only something that breaks the holding path, or an explicit reset, can stop it.
- If your stop is a contact in the holding path, ask whether it conducts or blocks while STOP is pressed. You need it to block.
- Check the restart too: after STOP is released, a fresh START must run the motor again.
I/O Table
Inputs
STARTStart push-button (momentary NO)
BOOL · %I0.0
STOPStop push-button (TRUE = pressed)
BOOL · %I0.1
Outputs
MOTORMotor contactor
BOOL · %Q0.0
Your program will be tested against:
All test cases run automatically when you submit. Assertions are hidden until you pass.
- #1Pulse STOP → MOTOR off
STOP switches a running motor off
- #2Pulse START → MOTOR on
A momentary START runs the motor and it holds after release
- #3Restart after stop → MOTOR on again
After a stop, a new START runs the motor
- #4STOP alone → MOTOR stays off
Pressing STOP never turns the motor on
Related scenarios
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