Ladder logic and Function Block Diagram programming in the browser — no install, no account
A Programmable Logic Controller (PLC) executes a repeating scan cycle: read all inputs, evaluate the program logic, write all outputs, then repeat. MakersDeck's PLC Simulator runs this cycle in real time inside the browser, letting you build ladder or FBD programs and watch them control a virtual plant.
Ladder diagrams use contacts (NO, NC, positive-edge, negative-edge) and coils arranged on horizontal rungs, mirroring relay-panel wiring. The simulator supports standard IEC 61131-3 instructions including TON / TOF timers, CTU / CTD counters, SR / RS latches, math blocks, and comparators.
Switch the editor to FBD mode and wire blocks together graphically. The same instruction set is available — timers, counters, and logic gates connect via data-flow wires rather than ladder rungs.
The Plant Builder provides 35 IEC-symbol components — motors, pumps, valves, tanks, conveyors, indicator lights, and sensors. Each component maps to a PLC tag; editing a switch or sensor input in the plant panel immediately drives the program inputs on the next scan.