PLC Simulator
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10 min

CCST 21 — E-Stop Circuit Basics

ccstsafetyestopfault-latch
CCST 21 — E-Stop Circuit Basics scenario preview

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Briefing

Implement a standard E-stop circuit: pressing ESTOP_PB immediately drops MOTOR_CONTACTOR and latches ESTOP_FAULT. Only after ESTOP_PB is released AND RESET_PB pressed does the fault clear.

Objectives

  • MOTOR_CONTACTOR drops immediately on ESTOP_PB
  • ESTOP_FAULT latches until reset
  • RESET_PB only clears fault when ESTOP_PB is released

Hints

  • Latch ESTOP_FAULT with SET on ESTOP_PB
  • Clear only when NOT ESTOP_PB AND RESET_PB
  • MOTOR_CONTACTOR := (START_PB OR MOTOR_CONTACTOR) AND NOT STOP_PB AND NOT ESTOP_FAULT

I/O Table

Inputs

START_PB

Start

BOOL · %I0.0

STOP_PB

Stop

BOOL · %I0.1

ESTOP_PB

E-stop (NC, asserted=tripped)

BOOL · %I0.2

RESET_PB

Reset

BOOL · %I0.3

Outputs

MOTOR_CONTACTOR

Motor

BOOL · %Q0.0

ESTOP_FAULT

E-stop fault lamp

BOOL · %Q0.1

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

  1. #1Motor drops on E-stop

    Motor drops on E-stop

  2. #2Fault stays after E-stop released

    Fault stays after E-stop released

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