Five instruments are shown in 3D: an electromagnetic flowmeter spool, a pressure gauge and transmitter, a radar level head, a glass pH electrode and an optical turbidity cell, plus a loop receiver and diagnostic panel. Set the actual process values, choose which instrument is selected, then compare actual value, measured value and loop current while changing response time and injecting faults.
• A real-time 3D view with numbered, clickable parts: electromagnetic flowmeter spool; pressure gauge and transmitter; radar level head and target surface; glass pH electrode and reference; optical turbidity sample cell; loop receiver and diagnostic panel. Scene tools include home view, focus-selected-part, auto-rotate, expand and show/hide labels, and drag-to-orbit with pinch-to-zoom. • Experiment controls: actual flow (20–120 m³/h); actual pressure (0–8 bar); actual level (0–4 m); actual ph (6–9); actual turbidity (0–10 NTU); selected instrument (flow / pressure / level / pH / turbidity); response time constant (0.5–8 s); selected-sensor fault (none / bias / stuck / dropout); bias as full-scale fraction (-0.2–0.2 fraction), plus a show flow/process markers toggle, pause/resume, single-step buttons (0.1 s and 1 s), a playback-speed selector and a restart trial action. • Live readouts: selected actual value; selected measurement; transmitter output; measurement error; signal usable. A model response curve is drawn beside the 3D view and updates as you change controls. • A Curves & measurements tab with two live charts, the model equations as written in the simulator and snapshot readouts; an Experiments tab with 2 guided presets (pressure signal bias; dropout indication) plus a model-verification bench, timestamped event log and copyable trial report. • A Learn & assess tab with 3 lessons (a measured value can lag reality; a plausible signal can still be wrong; fault current must not become a fake process value), a 2-question knowledge check with reset, and a written model-scope statement.
The transmitter state approaches the actual process value with a first-order response, so a larger time constant makes the measurement lag reality after a step. The selected measurement is converted to loop current with 4 mA at zero and 20 mA at the instrument span (flow 150 m³/h, pressure 10 bar, level 5 m, pH 14, turbidity 20 NTU).
The analysis tab charts actual and measured values together and the loop current separately, so you can relate delay and scaling to what a controller would actually receive.
A plausible signal can still be wrong. Bias adds a fraction of full scale to the reading and a stuck fault freezes the value; both remain inside the normal 4–20 mA range and so can go unnoticed. A dropout fault drives the loop to 3.5 mA and the model reports the measurement as unavailable with signal usable equal to zero, rather than showing a valid zero.
The model is idealized transmitter scaling with first-order response. It does not simulate accuracy class, wiring resistance, calibration certification or sensor chemistry, and the 3.5 mA dropout current is a chosen demonstration convention.
A live-zero signal lets a receiver distinguish a true zero reading (4 mA) from a broken loop (0 mA). The simulator also uses 3.5 mA to show a dropout condition.
The measurement follows the actual value as a first-order lag, so a larger time constant makes the reading rise or fall more slowly after a change in the process.
Bias and stuck faults keep the current inside the 4–20 mA range, so nothing looks alarming even though the value no longer matches reality. Comparing with another measurement is how such faults are caught.
The output falls to 3.5 mA, the signal is marked unusable, and the measured value is displayed as unavailable instead of as a valid process reading.