CIP Sequence Controller

Briefing

Clean-in-Place (CIP) is a fully automated cleaning sequence used in food and beverage processing. Your controller must step a vessel through five cleaning stages — Pre-Rinse, Caustic wash, Intermediate Rinse, Acid wash, and Final Rinse — each timed precisely. The pump and heater must be managed correctly per stage, and the FLOW_OK and TEMP_OK process interlocks must be satisfied before the cycle is considered healthy. Pressing STOP_PB at any time aborts the sequence and returns to IDLE.

Objectives

• START_PB begins the sequence from IDLE
• PRE_RINSE (3 s): open VALVE_RINSE + run PUMP_RUN
• CAUSTIC (6 s): open VALVE_CAUSTIC + run PUMP_RUN + HEATER_ON
• INTERMEDIATE_RINSE (3 s): open VALVE_RINSE + run PUMP_RUN
• ACID (4.5 s): open VALVE_ACID + run PUMP_RUN + HEATER_ON
• FINAL_RINSE (3 s): open VALVE_RINSE + run PUMP_RUN, then assert CYCLE_COMPLETE_LAMP
• STOP_PB aborts the sequence at any stage and closes all outputs
• FAULT_LAMP asserts if pump stops unexpectedly during an active stage

I/O Table

Your program will be tested against:

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

1. #1START_PB opens VALVE_RINSE and runs pump (PRE_RINSE)

   Press START_PB; VALVE_RINSE and PUMP_RUN must assert; no caustic or acid valve

2. #2CAUSTIC step opens VALVE_CAUSTIC + HEATER_ON

   After PRE_RINSE completes, VALVE_CAUSTIC and HEATER_ON must be on

3. #3Lost flow during an active wash latches FAULT_LAMP

   Start pre-rinse, then force FLOW_OK false after it had settled; the fault indicator must latch

4. #4CYCLE_COMPLETE_LAMP asserts after all steps finish

   Run the full sequence; CYCLE_COMPLETE_LAMP should assert at end

5. #5STOP_PB aborts mid-sequence and closes all outputs

   Start the sequence, press STOP during PRE_RINSE; all outputs must go off

6. #6ACID step opens VALVE_ACID and runs heater

   After pre-rinse + caustic + intermediate rinse, VALVE_ACID and HEATER_ON must be on