ClassicLadder is a software-based Programmable Logic Controller (PLC) seamlessly integrated into LinuxCNC to handle auxiliary machine logic. It allows users to program hardware and virtual automation loops using Ladder Logic, a graphical programming language that mirrors real-world electrical schematics.
If you are a beginner looking to manage CNC components like lube pumps, tool changers, or physical safety interlocks, this guide outlines the core concepts and steps to get started. Core Concepts: The Ladder Environment
Ladder logic uses visual elements arranged like a ladder, with two vertical power rails and horizontal rungs representing electrical circuits.
The Execution Flow: Power conceptually flows from the left rail to the right rail. Rungs are scanned systematically: first, inputs are read; second, the logic is calculated; third, the outputs are set.
“Last One Wins” Rule: If you assign the same output variable to multiple rungs, the state defined by the very last rung in the scan order determines the final hardware output. Key Programming Symbols & Variables
Variables in ClassicLadder use distinct percentage-based formatting tags: ClassicLadder Programming – LinuxCNC