The Controller Area Network (CAN) protocol is a widely used event-triggered communication protocol, which oers high average performance, exibility, and extensibility. However, time-triggered protocols are becoming more and more accepted as the communication infrastructure for safety-critical applications, since they support composability, dependability, and a deterministic behavior of all message transmissions. The desire to reuse CAN based legacy applications as part of time-triggered systems

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... otivates the provision of CAN communication services within a time-triggered environment. This paper elaborates on an approach of layering CAN on time-triggered communication services. A node that participates in this CAN emulation reserves a part of its sending slot for implementing a packet service, thereby establishing a communication channel, a way of transferring a sequential data stream of CAN messages. Furthermore, the emulation oers an improved CAN communication service by addressing deciencies of the basic CAN protocol. The CAN emulation exploits the faulttolerance mechanisms of the underlying time-triggered system for extending CAN with support for dependable systems. II. Event-Triggered and Time-Triggered Communication Systems The Controller Area Network (CAN) belongs to the class of event-triggered (ET) protocols. In this section the event-triggered and time-triggered (TT) paradigms are discussed. The properties of a TT communication system and its benets for real-time systems are elaborated. Furthermore, CAN-specic limitations and peculiarities are described. A distributed real-time application can be decomposed into a controlling computer system and a con-