E-Stop & Safety Reset

Briefing

Standard safety reset circuit. ESTOP is wired normally-closed (true = healthy, false = asserted). When the E-stop is hit (ESTOP goes false) the machine immediately drops MACHINE_ENABLE and latches FAULT_LAMP. Resuming operation requires: (1) E-stop cleared, (2) RESET_PB pressed to extinguish the fault and illuminate READY_LAMP, (3) START_PB pressed to re-enable the machine.

Objectives

• ESTOP asserted (false) drops MACHINE_ENABLE and latches FAULT_LAMP
• While fault is latched, MACHINE_ENABLE and READY_LAMP stay off
• RESET_PB pressed with ESTOP cleared extinguishes FAULT_LAMP and sets READY_LAMP
• START_PB pressed while READY_LAMP is on energises MACHINE_ENABLE (seals in)
• MACHINE_ENABLE drops immediately on any new ESTOP

I/O Table

Your program will be tested against:

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

1. #1E-stop asserted drops MACHINE_ENABLE and latches fault

   Start machine then hit E-stop — enable drops immediately, fault latches

2. #2Fault stays latched after E-stop released without reset

   Releasing E-stop alone must NOT clear the fault

3. #3RESET_PB clears fault and sets READY_LAMP

   E-stop cleared then RESET_PB pressed — fault clears, ready lamp illuminates

4. #4START_PB energises MACHINE_ENABLE when READY_LAMP is on

   After reset, pressing START_PB enables the machine

5. #5RESET_PB cannot clear fault while E-stop is still asserted

   Press reset while E-stop still active — fault must stay latched