Efficient Implementation of Semaphores in Controller Area Networks

Synchronization of concurrent activities by means of semaphores is widely adopted in industrial distributed systems. This paper presents some mechanisms which facilitate the efficient implementation of the popular semaphore concept in real-time networks based on the controller area network medium access technique. The advantages obtained by adopting the proposed solution are twofold. First, better performance can be obtained because most of the semaphore management mechanisms are moved from the application to the physical and data-link communication layers. Second, a fully distributed management scheme is implemented, and there is no need to place the semaphore control structures on a particular node in the network