Reverse-acting is correct here: valve on inflow, raising CO raises level.
Simulation
1.0x
Response Metrics (since last SP step)
Overshoot
–
Rise time
–
Settling time (±2%)
–
Steady-state error
–
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.
Process Setup — pre-defined (instructor)
These define the plant this exercise simulates — tank geometry, valve sizing, actuator dynamics, dead time, and load. They're set up ahead of time, not tuned live; in a future student mode this whole section is hidden, and a student just sees the process they were given.
30
100
2.0
1.0
Steady state check: at CO 50% and demand 50, inflow = outflow → level holds.
Kp ≈ – Ki ≈ – /s Kd ≈ – s
PB ≈ –, Reset ≈ –, Rate ≈ – | Ti ≈ –
Stability limit — Ultimate gain Ku ≈ –, Ultimate period Pu ≈ –