Response Metrics (since last SP step or disturbance)
Overshoot
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Rise time
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Settling time
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Steady-state error
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Auto-Tune
Run a step-response bump test and get a suggested tuning — like a real PLC/DCS auto-tune.
For Students — Things to Try
Step the setpoint (SP 25 / 50 / 75 buttons) and watch how PV chases it. Read the Response Metrics panel after each step.
Increase Kp / lower PB and step SP again — response gets faster but may overshoot or start to oscillate.
Remove reset (increase Reset time / lower Ki toward 0) — notice the loop settles with a permanent steady-state (offset) error instead of returning exactly to SP.
Bump the load — this is a disturbance, not a setpoint change; watch the controller reject it and return PV to SP.
Add rate (Td) — a little derivative can reduce overshoot on aggressive tunings, but too much amplifies noise.
Switch to Manual, move the output, then flip back to Auto — notice CO does not jump (bumpless transfer).
Increase actuator lag or dead time — the same tuning that was stable before may now overshoot or oscillate: a preview of why real loops need re-tuning when valves/actuators change.
Auto-Tune — Step Response
Bumps the controller output (CO) by a set amount and records how the process
responds, then identifies a process model and computes a Ziegler–Nichols tuning from it — the
same general idea real PLC/DCS auto-tune features use.
Test running — recording the reaction curve. Setpoint / Outflow controls are
locked until this finishes.
Elapsed
0.0 s
CO
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PV
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Identified process model (from the bump test — not the sim's true parameters)
Process gain K′ (%/s per %CO)
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How fast the level ramps for every 1% the valve opens.
Apparent dead time L
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Time constant T
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Ziegler–Nichols tuning (reaction curve)
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Instructor Panel
True process parameters
Optimal tuning for this process
Instructor notes
Instructor-only — not visible to students. Ctrl+Alt+I toggles this panel.