// FEATURE
Simulate mode now includes a real, programmable PLC — the same jump a working electrician’s toolkit makes, wired straight into the physics engine rather than laid over it as a diagram.
// WHAT SHIPPED
A placeable PLC component — a real ladder-logic editor, on-device I/O forcing, and a purpose-built faceplate — now sits inside Simulate mode alongside contactors, breakers, motors, and timers.
Relay panels are being replaced by PLCs across the trade. This is the first place a student gets to make that exact jump themselves, not just read about it in theory class.
// HOW YOU MEET IT
It’s dragged onto the canvas exactly like any other Simulate-mode part — its own toolbar category, same tier as the VFD and the transformer. The faceplate is a small on-screen display plus a real navigation pad: Up, Left, Right, Down, OK, ESC, and a dedicated I/O button.
The design is deliberately generic — not a reproduction of any specific commercial unit — but the functional layout (I1–8 / Q1–4 status indicators, a run light) is the same one any industrial PLC shows on the wall.
“Industrial digital computer for automation — reads digital/analogue inputs… executes user-programmed logic (commonly Ladder Logic)… Replaces large banks of relay logic with one programmable, reprogrammable device.”
Wiring Simulator component reference
// THE EDITOR
You build real rungs:
It also checks your work as you go: it flags a contact wired to nothing (“will always read as false”), and a contradictory NO+NC pair on the same input in one branch — an always-false condition, the same category of mistake a real commissioning engineer is trained to catch before power-up.
// I/O FORCING
Press OK on the faceplate and force any input or output to a fixed value — override the real wiring and see exactly what’s downstream. It’s the same move used to commission a real panel before all the field wiring exists, or to isolate a fault once it does.
Forced points render in their own colour in both states, so nothing reads as a mystery dead button — the interface says, unambiguously, this is forced. Forceis the actual word electricians use for this on real hardware — it isn’t simulator jargon.
// WIRED INTO THE REAL ENGINE
Same scan-cycle power-flow logic as every other component: it only evaluates once its own supply is genuinely reachable, on separate phases, exactly like a real unit. An unpowered PLC can’t be forced into working, same as the real thing.
Its inputs read real wire connectivity. Its outputs gate real relay edges downstream — so a PLC built in Wiring Simulator can genuinely switch a simulated contactor, lamp, or motor circuit, the same as it would wired into an actual panel.
// BUILT TO SPEC
Terminal connection limits follow SANS 10142-1 §6.1.5, the same standard the rest of the simulator is validated against. It’s backed by a dedicated automated test suite — contact polarity, branch logic, timer state machines including re-trigger and boundary cases, forced I/O, and full end-to-end runs through the live engine.
“Each of these reproduces a real bug found (and fixed…) in a live debugging session, so a future change that reintroduces any of them fails loudly here instead of silently.”
Wiring Simulator PLC engine test suite
| Spec | Detail |
|---|---|
| Inputs | I1–I8 — 8 digital inputs |
| Outputs | Q1–Q4 — 4 isolated relay outputs, each with its own NO + COM (no shared bus) |
| Timers | TON (on-delay), TOF (off-delay) — real elapsed time |
| Logic | NO/NC contacts, internal memory bits, nested branch networks |
| I/O forcing | Any input or output, either state |
| Programs | One per PLC instance — independent per unit, multiple PLCs per circuit |
| Standard | SANS 10142-1 §6.1.5 (terminal connection limits) |
| Mode | Simulate mode only |
The PLC is available in Simulate mode. It doesn’t appear in the SANS/IEC reference circuits covered in Schematic Mode.