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4 templates · Ladder logic

PLC Automation Ladder Diagram Examples

Ladder diagrams are the PLC programming language: each rung is a logic statement, contacts are conditions, coils are outputs, and the left/right rails are power rails. They look like relay logic because they replaced it.

Standard IEC 61131-3 Ladder DiagramEngine schematex-ladderExport SVG · PNG · PDF
4 templates
Ladder logic PLC Automation
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Nothing close enough? Start from a blank ladder logic → Describe it in one paragraph.

How to

How to use a ladder logic template.

  1. 01Define the I/O tags

    Name the inputs (sensors, pushbuttons) and outputs (motors, solenoids) — these become the contact and coil symbols.

  2. 02Describe each rung

    Say what condition enables each output — the AI translates "if A AND B then C" into contacts and a coil on a rung.

  3. 03Add timers and counters (optional)

    Describe timer-on-delay or counter logic and the AI adds the standard function block symbols.

  4. 04Review the interlock logic

    Check that safety interlocks (normally-closed contacts) are modeled correctly before exporting for PLC review.

FAQ

Questions about ladder logic templates

What is a ladder diagram?

A graphical programming language for PLCs that represents control logic as rungs between two vertical power rails — left for power, right for neutral. Contacts (inputs) and coils (outputs) form the rung logic.

What does a normally-open vs normally-closed contact mean?

A normally-open (NO) contact passes current only when the associated input is ON. A normally-closed (NC) contact passes current when the input is OFF — used for safety interlocks and emergency stops.

Can I use ladder diagrams for all PLC logic?

Ladder is best for combinational and simple sequential logic. For complex sequential processes, Function Block Diagrams (FBD) or Sequential Function Charts (SFC) may be more appropriate. ChatDiagram supports all four IEC 61131-3 graphical languages.