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.