Applying quality of service architectures to the field-bus domain

Communication between intelligent sensors, actuators and controller components imposes stringent requirements on timeliness and predictability. Thus field-bus standards such as PROFIBUS, EIB, or CAN support deterministic priority-driven media access. These mechanisms are sufficient for static settings where communicating peers as well as traffic loads are known in advance and priorities can be assigned prior to system operation. In environments where, e.g., communicating devices may change dynamically we need to provide additional mechanisms for admission control and traffic policing, which operate during system activity. Local and Wide area networks have to meet similar requirements, which led to the development of so-called quality of service architectures. We argue that many of these concepts are also adequate to the field-bus domain and adapt them to the CAN protocols. As a basic means to achieve timeliness and predictability we employ rate monotonic analysis.