Fix 01 — Motor won’t hold
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Briefing
This program lights the motor while START is held and drops it on release. Make it hold. Run it first and watch MOTOR: tap START and the motor goes out again immediately. Change the program so a quick tap leaves the motor running, and it stays off until START is pressed.
Objectives
- A quick tap of START leaves MOTOR running
- MOTOR stays off until START is pressed
Hints
- Watch MOTOR while you hold START, then let go. What does the rung still know about the button after it is released?
- A normal output coil only follows its contact: when the contact opens, the coil forgets. The motor needs a way to stay on by itself.
- There are two ways to remember. A coil can latch its state, or the motor can be given a second path that keeps it on once it is running.
- Whichever you choose, MOTOR must be off before START is pressed and still on a while after you let go.
I/O Table
Inputs
STARTStart push-button (momentary NO)
BOOL · %I0.0
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.
- #1Tap START → MOTOR stays on
A momentary START leaves the motor running after release
- #2Idle → MOTOR off
Without pressing START, the motor stays off
- #3Two seconds after the tap → MOTOR still on
The motor keeps itself running, it does not just linger briefly
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