A Protocol for Automatic Node-ID Binding in CANopen Networks

In a CANopen-compliant industrial control system, the master node controls slave nodes (devices) through the corresponding Node-IDs. Though there are some protocols (such as LSS, LMT etc) established for Node-ID assignment, it is not competent for configuring Node-ID for all slaves automatically. In this paper, a new Node_ID binding protocol is proposed. The protocol can be used to assign Node-IDs to all the slave nodes of a networked control system automatically, and the assigned Node-ID can also reflect the logic position of a physical slave node in the control system. Firstly, the LSS physical address structure is applied to a developed protocol for automatic node discovery (AND) with some necessary modifications. The revision of the AND protocol (RAND) is proved to be able to detect LSS addresses of all slaves efficiently. After all the slave nodes being discovered, each slave node needs to be assigned with an appropriate Node_ID. In the proposed protocol, the assignment is divided into two phases: the Node-IDs pre-assigning phase and the Discovery and binding phase. The accomplished function, the implementation rules and the sorting algorithms of the two phases are described in detail. Finally, the performance of the protocol is evaluated both from a theoretical point of view and by means of a network emulator. The latter approach also verified the correctness of the protocol under actual conditions. It is illustrated that with the proposed protocol, it is easier to deploy and maintain a control system.