Combining event-triggered and time-triggered traffic in FTT-CAN: analysis of the asynchronous messaging system

For some years, there has been a debate opposing event-triggered and time-triggered traffic paradigms in fieldbuses. While the former is better suited to sporadic sources of information, the latter is more suited to periodic streams of information. However, for certain applications, such as flexible real-time systems, a combination of both paradigms is desirable. The authors have recently proposed a new controller area network (CAN) based protocol, called FTT-CAN (Flexible Time-Triggered communication on CAN), that supports time-triggered communication in a flexible way. It also allows an efficient combination of both time-triggered and event-triggered traffic with temporal isolation. This paper describes the asynchronous messaging system of the FTT-CAN protocol which is responsible for the support of event-triggered traffic. Furthermore, a response time analysis is carried out concerning the handling of asynchronous communication requests.