This is your bible. It covers the IDE itself—the editor, the debugger, the task configuration, and the visualization manager.

CODESYS (Controller Development System) is one of the most widely used hardware-independent automation software platforms globally. Developed by the German company 3S-Smart Software Solutions (now CODESYS Group), it provides a complete Integrated Development Environment (IDE) for engineering controller applications. The version 3.5 series represents a mature, robust, and continuously evolved iteration of the software, adhering to the IEC 61131-3 standard. This text serves as a manual-style overview, covering the architecture, programming languages, project management, visualization, and deployment specific to CODESYS 3.5.

The manual will tell you exactly that you need to check wState = 5 and that a value of 2 means "Init" (no communication). You fix it in five minutes.

: Features a library manager to display all referenced libraries and document library features. Engineering & Debugging Tools