RUNG/RUN

A black-and-white, large-type PLC lesson that makes teaching the first visual priority. The opening screen explains a complete START + GUARD → MOTOR rung, followed by a READ INPUTS → SOLVE LOGIC → WRITE OUTPUTS scan cycle and nine scroll-driven symbol chapters. A full Build-a-Rung workbench lets learners replace both contacts with NO or NC, switch SERIES/AND to PARALLEL/OR, swap COIL for TON or CTU, toggle the inputs and watch the path, Boolean equation, timer and edge counter change live. A separate motor lab and accessible fault-tracing challenge turn every symbol into observable behavior. All diagrams are original HTML, CSS and SVG with no external media.