A protocol for automatic node discovery in CANopen networks

The correct operation of the CANopen protocol relies on the assumption that each node in the network be identified uniquely. To this extent, the CANopen specifications provide a means to remotely configure the addresses of the slave devices attached to the CAN bus. This technique, however, requires that each device has to be connected separately to a configuration tool. CANopen, in fact, does not have a mechanism to identify, in an efficient and reliable way, the nodes that do not have an associated address when they have already been connected to the network. In this paper, we present a new automatic node discovery protocol, which is able to eliminate such drawbacks. Our technique can be used to identify the nonconfigured nodes directly in the final system and is conceived as an extension of the basic layer setting services of CANopen, so as to provide a very good degree of compatibility with the existing devices. Index Terms--Communication protocols, Controller Area Network (CAN), field buses, industrial control, manufacturing automation.