Two-Hand Control (Safety)

Briefing

Two-hand control is a Type-III safety device used on presses and stamping machines. Both BUTTON_A and BUTTON_B must be pressed within 500 ms of each other and held simultaneously for at least 200 ms, with GUARD_OK also active. If only one hand is pressed and 500 ms elapse before the other, a fault latches. Releasing either button immediately drops CYCLE_START. The fault latches until both buttons are released.

Objectives

• Both buttons pressed within 500 ms window (with GUARD_OK) → CYCLE_START after both held 200 ms
• Releasing either button immediately drops CYCLE_START
• One button pressed and held >500 ms without the other → FAULT_LAMP latches
• FAULT_LAMP clears automatically when both buttons are released
• GUARD_OK must be true throughout; opening guard drops CYCLE_START and latches fault

I/O Table

Your program will be tested against:

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

1. #1Both buttons pressed together triggers CYCLE_START

   Press both buttons simultaneously with GUARD_OK — CYCLE_START after 200 ms hold

2. #2Releasing either button drops CYCLE_START immediately

   While CYCLE_START is active, release one button — output drops

3. #3Single button held >500 ms without second button latches fault

   Press BUTTON_A only — after 500 ms window expires FAULT_LAMP latches

4. #4Fault auto-clears when both buttons released

   After a tie-down fault, releasing all buttons resets the fault

5. #5GUARD_OK must be true for CYCLE_START

   Both buttons held but GUARD_OK false — CYCLE_START stays off