The Industrial Ethernet has become a way to build distributed systems in industrial networks which must provide predictable performance and maintainability. Industrial applications require time-critical processing, which can be guaranteed within soft or hard real-time environments, Where applications' responses require deterministic processing time, the hard real-time environment is requested. The Fieldbus protocols are the standard way to connect instruments on the Ethernet-based communication. Fieldbuses require synchronisation and dedicated application-specific integrated circuits, what leaves space for alternate, more common solutions. This thesis presents design, implementation, and evaluation of the novel Real-Time Driver Model asynchronous communication stack called 61850CS API. 61850CS stack is implemented in an intelligent electronic device to enable real-time IEC 61850 GOOSE Ethernet communications in electrical substations. The presented 61850CS implementation enables simultaneous flow of real-time and non-real-time Ethernet traffic over the same physical network interface controller. The same technology supports running arbitrary real-time Ethernet traffic and non real-time Ethernet traffic simultaneously and its implementation is general enough to enable an API use on different architectures and to comply with different industrial Ethernet requirements. And more, since 61850CS doesn't affect CSMA/CD mechanism, it doesn't need any master nodes, which increases the system availability.
The presented solution was implemented as an application programming interface for feeder protection and control (FPC 680) intelligent electronic device relay. Hardware platform for 61850CS was PPC440EPx microcontroller with implemented Linux Real-Time application interface RTOS. The FPC 680 is an IED commercial product by Iskra d.d. which is implemented worldwide in several substations.