Pump Alternation (Duty/Standby)

Briefing

A water/wastewater lift station uses two pumps in a duty/standby arrangement. The duty (lead) pump starts whenever the tank reaches the high level and stops when it drains to the low level. After each completed pump cycle the duty assignment swaps so both pumps accumulate equal runtime. If the duty pump fails (PUMP1_FAULT or PUMP2_FAULT asserted) the standby pump takes over immediately. If both pumps fault simultaneously, COMMON_FAULT latches and stays on until RESET_PB is pressed with both faults cleared.

Objectives

• LEVEL_HIGH starts the duty pump; LEVEL_LOW stops it
• After each fill cycle (LEVEL_HIGH deasserts) the duty pump alternates: Pump 1 → Pump 2 → Pump 1 …
• PUMP1_FAULT causes Pump 2 to become active immediately
• PUMP2_FAULT causes Pump 1 to become active immediately
• Both faults simultaneously latches COMMON_FAULT (cleared by RESET_PB once both faults clear)
• PUMP1_LAMP and PUMP2_LAMP mirror their respective RUN outputs

I/O Table

Your program will be tested against:

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

1. #1Pump 1 (duty) starts on LEVEL_HIGH

   With no faults and tank rising, PUMP1_RUN asserts when physics raises LEVEL_HIGH

2. #2Duty pump stops on LEVEL_LOW

   Once running, the pump stops when physics lowers the level to LEVEL_LOW

3. #3Duty pump alternates after each cycle

   After one complete cycle (LEVEL_HIGH → LEVEL_LOW), Pump 2 becomes duty

4. #4PUMP1_FAULT causes Pump 2 to take over

   When Pump 1 is duty and faults, Pump 2 starts immediately

5. #5Both faults latch COMMON_FAULT

   PUMP1_FAULT AND PUMP2_FAULT simultaneously latches COMMON_FAULT; RESET_PB clears it