wtf is kn_plc?

This is a visual editor for programming industrial controllers. Specifically, it lets you create "ladder logic", a graphical programming language used in factory automation, and upload that logic to a device called the KN PLC, which is built around an Arduino Mega 2560 board. Instead of writing code, you draw circuits that look like relay wiring diagrams. You arrange inputs and outputs on rungs of a ladder, and the software translates that visual design into instructions the controller can run. Once you're happy with your logic, you upload it directly to the Arduino-based hardware. The tool supports controllers with 8 digital inputs, 8 digital outputs, 8 auxiliary relays, 2 counters, and 2 timers. The README includes a pin mapping table showing exactly which Arduino pin corresponds to each input and output, and it notes that you should use pull-down resistors to avoid signal flickering. This would appeal to hobbyists, educators, or small-scale automation projects where someone wants to control physical devices, like sensors, motors, or lights, using familiar industrial programming concepts. The Arduino Mega foundation makes it accessible compared to commercial PLCs that can cost hundreds or thousands of dollars. On the technical side, the editor is built with Qt (a desktop application framework) and relies on PlatformIO to handle the upload to the Arduino. You'll need both installed for the tool to work. The README's build instructions target Windows using MinGW, and the project appears to be in a fairly early stage. Beyond the basic feature list and pinout, it doesn't go into much detail on advanced capabilities.