CAN assessment in time-critical cyclic applications through Petri net model

The authors discuss problems relating to use of the CAN (controller area network) fieldbus in time-critical process control applications. Certain characteristics of the CSMA/CD protocol, such as the reduced size of the frames with simplified headers and the use of an approach based on nondestructive collisions, allow optimal exploitation of the communication bandwidth. Moreover, the use of a priority-based approach to solve collisions provides a form of implicit scheduling, similar to the rate monotonic algorithm, which allows traffic to be organized correctly, according to the time constraints of the various variables. In the paper, after presenting the main features of the CAN, the problem of correct traffic scheduling is dealt with. A system model based on Petri nets is presented and evaluated. The results of the simulations performed show that CAN is suitable for several time-critical applications