A Java client/server system for accessing arbitrary CANopen fieldbus devices via the Internet

Abstract

This paper describes the Java CAN API a portable and extensible application interface to arbitrary CANopen fieldbus devices. This API forms the basis for the implementation of JRCC (Java Remote CAN Control), a tool which can be used to retrieve and modify the whole set of status parameters of arbitrary CANopen devices via the Internet, providing the basic facilities for remote maintenance, remote data acquisition and remote control of CANopen nodes. In an educational context this opens up the opportunity to demonstrate and to experience the behavior of various CANopen modules with respect to specific status modifications, independent of the local availability of those devices. Since we choose a Java client/server software architecture using TCP/IP sockets, the JRCC client can easily be embedded in an ordinary HTML web page and be executed by any web browser featuring a Java 1.1 compliant virtual machine. The abandonment of a middleware layer results in an extremely small and portable system with high availability and little system requirements, making this approach a candidate for both, a low cost embedded system solution for remote access to CANopen devices and a fieldbus teaching tool for the potentially heterogenous client system environment of a distributed collaborative learning community connected via Internet.