Virtual fault-finding simulator

Scenario packs

Day 2 · Hardwired field devices

An AHU training panel with two thermistor temperature sensors and a 0–10 V duct pressure transmitter. Warm or disconnect sensors, isolate circuits, take multimeter readings at the panel and at the device, and compare against the BMS front end and reference instruments.

Day 3 · RS-485 / Modbus network

A six-device Modbus RTU daisy chain. Read device addresses and EOL switches, inspect terminations, segment the network with a temporary end and measure A–B resistance with the network isolated.

End-to-end cable continuity (all benches)

The meter's continuity range beeps with the Ω value shown below about 50 Ω and reads OL above that (a mute toggle is provided; it is blocked on live circuits). Prove a pair end to end by joining the cores at the far end — either clip a temporary test link (strap) across the two device terminals, or pull the cores out and push them into a lever connector block (the device is then out of circuit) — and measure from the panel end, field side and isolated: a low loop reading (both cores in series, about 0.4–1.5 Ω) proves both cores. Take the strap or block off and confirm OL, then test each core to earth/screen (OL). A wander lead extends the black probe to the field device for single-core and core-to-earth checks. A swapped pair shows the loop on the wrong circuit; a short shows continuity with nothing fitted. Restore checks flag a strap left on or cores left in the block.

In every pack you can drag a core out of its terminal by its ferrule to open-circuit it, probe the loose core, then drag it back onto its own terminal to re-land it. Some scenarios hide a loose or unlanded core for you to find.

Tools and records

• Multimeter with mA range: move the red lead to the mA socket and measure loop current in series. Connecting the meter on mA in parallel across a supply is blocked, as a real meter's fuse would blow.
• Signal injector: drive 0–10 V or mA into a BMS input and check the front end follows the scaling (for example, 5 V on a 0–10 V = 0–500 Pa input should read 250 Pa). Open the disconnect link first: injecting into a live transmitter output is flagged as bad practice.
• Drawing view: open the wiring drawing beside the rig (or in place of it on a phone). Tap a terminal on either one to highlight it on the other.
• Point-to-point and defect sheet: record each point's device, terminals, expected and measured values, result (Pass, Fail, Defect or Blocker) and notes, plus any defects. Measured values fill in from your meter readings. Download it as an A4 PDF with your name, the date, the scenario ID, your score and an assessor sign-off box.