Lesson 2 — E-Stop (NC contact)
Ready to build this?
Sign up free — no credit card required. This scenario is included in the free tier.
Sign up to play this scenario →Already have an account? Log in
Briefing
ESTOP is wired as a normally-closed (NC) contact — it passes power when the button is NOT pressed. The light stays on unless you hit the e-stop. This is why e-stops are always NC: a broken wire or unplugged button safely de-energises the output.
Objectives
- When POWER_ON is true AND ESTOP is not pressed, LIGHT turns on
- When ESTOP is pressed (true), LIGHT turns off
Hints
- Use a NO contact for POWER_ON and a NC contact (/ESTOP or NOT ESTOP) in series.
- In IEC ladder syntax: | POWER_ON /ESTOP | := LIGHT ;
I/O Table
Inputs
POWER_ONEnable push-button (NO)
BOOL · %I0.0
ESTOPE-stop (NC in circuit)
BOOL · %I0.1
Outputs
LIGHTIndicator lamp
BOOL · %Q0.0
Your program will be tested against:
All test cases run automatically when you submit. Assertions are hidden until you pass.
- #1POWER_ON + no estop → LIGHT on
Light should be on when powered and e-stop is not pressed
- #2ESTOP pressed → LIGHT off
Pressing e-stop must immediately de-energise the light
Related scenarios
Ready to build this?
Sign up free — no credit card required. This scenario is included in the free tier.
Sign up to play this scenario →Already have an account? Log in