Proposal and Evaluation of dynamic assignment of priorities in CAN

The paper presents a protocol for dynamic priority assignment in two CAN-based standards: CAL CiA and CANOpen. The proposal allows achieving a better respect of real time constraints in CAN fieldbus. The proposal is relevant from the scientific point of view, as it represents the only solution known in literature, perfectly compliant with standard Application Layers, as shown in the paper. Other approaches to improve real time features of CAN system are present in literature, but they mainly adopt a proprietary application and/or user layer upon the standard Data Link and Physical CAN layers. Paper clearly points out the advantages in proposing a real time solution using a standard application layer. The impact of the proposal is not limited to academic environment. The adoption of standard application layer services and protocol allows a very easy and fast software implementation using existing commercially available CAL CiA and/or CANOpen libraries; in this way, many industrial applications may take advantage from a development of software realising the protocol here presented, using CAN software and hardware already existing in the industrial environment.