Catalog · CODESYS Beginner · Ladder logic fundamentals

Contacts and coils

Draft lesson — skeleton content pending the founder’s course outline (issue #32).

Ladder logic descends directly from relay wiring diagrams: power rails on the sides, contacts (conditions) in the middle, coils (results) on the right.

In the IDE

Create a new project from your course template in C:\Projects, open PLC_PRG, and add a rung:

  • a normally-open contact bound to bStartButton
  • a coil bound to bMotorRun

Download to the PLC and set the PLC to Run. Toggle bStartButton from the watch list and watch bMotorRun follow it — you’ve written the automation equivalent of “hello, world”.

Why this matters

Every interlock, latch and sequence you’ll ever write reduces to arrangements of these two primitives plus timers and memory. Next: making an output stay on — the seal-in.

Open lab for this course → Runs in your browser — your own IDE, PLC and machine.