Hard real-time communication software development techniques

Since fieldbusses have to fulfil very hard real-time constraints, traditionally, they are implemented in hardware or in microcode on specialized microcontrollers. As a result, minor changes in the protocol may lead to time consuming efforts for implementing the update. This paper presents a different approach. We show that it is possible to implement communication protocols with very hard real-time constraints using a general purpose microcontroller and a high level language. The paper presents a software implementation of the FIP fieldbus communication protocol and the major techniques used in this implementation. The paper also indicates the major reasons why we adopted this software approach instead of using the traditional hardware approach.