This repository contains CANopenNode, a full-featured, portable ANSI C implementation of the CANopen protocol stack compliant with EN 50325-4 (CiA 301) and related standards (CiA 302, 303, 304, 305, 309). It is designed for embedded microcontrollers and real-time industrial automation systems. The stack implements Network Management (NMT) with heartbeat and node guarding, SDO server/client with expedited/segmented/block transfer, PDO with dynamic mapping, Emergency messages, SYNC, Time-stamp, LSS, Safety-Related Data Objects (SRDO), and an ASCII gateway for remote management (CiA 309-3). The architecture is modular, with each protocol in its own directory (301/, 303/, 304/, 305/, 309/). Central orchestration is provided by `CANopen.c` with a main processing loop `CO_process()` that should be called cyclically. The stack is configuration-driven via compile-time macros in `CO_config.h`, allowing feature enable/disable to reduce footprint. A hardware abstraction layer (`CO_driver.h`) separates CAN bus specifics, and example blank drivers (`CO_driver_blank.c`, `CO_storageBlank.c`) facilitate porting to new platforms. Key design patterns include a generic Object Dictionary interface with extension callbacks, a reusable circular FIFO buffer with protocol parsing, storage abstraction with CRC integrity, and non-blocking state machines. The codebase adheres to MISRA C:2012 (with documented exceptions) and includes Doxygen documentation. While primarily a library, the repository contains an example application skeleton and a generated device profile XML. Technical debt includes the FIFO and gateway modules being excluded from static analysis, certain static variables limiting reentrancy, and the trace feature being non-functional. The project is actively maintained with a large user base and multiple derivative repositories for specific platforms (Linux, STM32, PIC, etc.).