PID Temperature Control

Briefing

A single-vessel reactor with a continuously-variable electric heater and an optional cooling fan disturbance. Your job is to configure a discrete-time PID loop (the platform ships a PID function block) so that pressing START drives the temperature up to a 60 °C setpoint without overshooting past 70 °C, holds it there, and survives a 60 s fan disturbance still tracking within ±3 °C. A separate safety latch — independent of the PID — must observe a TEMP_HIGH signal (process > 95 °C) and latch an ALARM output that stays on until STOP is pressed after the temperature has recovered. A READY lamp lights after the loop has stayed within ±1 °C of setpoint for 10 s continuously. The PID block is declared as a typed function-block instance (TEMP_PID : PID;) and called with the standard named-argument form: TEMP_PID(SP := 60.0, PV := TEMP_PV, Kp := …, Ki := …, Kd := …, MIN := 0.0, MAX := 100.0, DT_MS := 50, ENABLE := RUN);. The block's commanded output (TEMP_PID.CV) is piped directly into the thermal physics — your tuning is what makes the plant track. Use Kp around 2.0, Ki around 0.3, Kd around 0.5 as a starting point and refine from there.

Objectives

• Latch a RUN bit: SET on START, RESET on STOP
• Declare a PID function-block instance (TEMP_PID : PID;) and invoke it once per scan with sensible PID gains (Kp, Ki, Kd), MIN=0, MAX=100, DT_MS=50, ENABLE := RUN
• Use the platform-provided IN_TOL discrete input through a 10 s TON to drive READY
• Use the platform-provided TEMP_HIGH discrete input through a SET/RESET latch to drive ALARM; clear on STOP once TEMP_HIGH has released
• Keep the closed-loop transient below 70 °C (no severe overshoot) and steady-state within ±1 °C of 60 °C

I/O Table

Your program will be tested against:

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

1. #1PID tuning converges to setpoint within ±3 °C

   After pressing START, the PID must drive temperature from ambient (20 °C) to setpoint (60 °C) and settle within ±3 °C inside 120 s.

2. #2Temperature never rises past 70 °C during the transient

   With conservative tuning the process temperature must not overshoot setpoint (60 °C) by more than 10 °C on the way up.

3. #3Process recovers within ±3 °C of setpoint with fan disturbance on

   Bring the loop to steady state, then turn the cooling fan on for 60 s — the loop must still be within ±3 °C of setpoint at the end.

4. #4ALARM latches on TEMP_HIGH and stays on after the fault clears

   Inject TEMP_HIGH = true for one scan. ALARM must latch on within the following scan and stay on even after TEMP_HIGH returns to false.