Design And Implementation Of The Communication System For The Distributed Multi-Axis Motion Control System Based On CAN Bus

Fieldbus is used in the work field and committed to realize the dual serial multi-node digital communication scheme between the computer measurement and control devices. It is also called an open, digital and multi-node communication control network at low level. The emergence of fieldbus was a start of the new era in the industrial control technology field.CAN, Controller Area Network, is a member of the fieldbus family. It is a bus-based serial communication network which can efficiently support the distributed control or real-time control system. Comparing with other fieldbuses, CAN has much reliable, real-time and flexible data communication capabilities.Firstly, the author gives a brief introduction to the CAN fieldbus and explains its technological features and protocol standards. As to the communication system for the distributed multi-axis motion control system based on CAN bus, the author analyzes the requirements of the system and makes the overall design for it. The main items of the overall design are network topology of the communication system, the hardware structure and software structure of the communication system. The key point of the overall design is focused on the design and implementation for the CAN nodes.The hardware structure of the CAN node is made up of micro controller unit, CAN controller and CAN receiver/sender. Regarding the software structure of the CAN node, the author develops the communication software module, which is also the most important part in this thesis. The communication software module consists of the application layer protocol module, the generic communication module and the motion control application module. In the application layer protocol module, the author discusses the structure design of the message identifiers, the structure design of the data field in the message, the methods of data exchange and the message filter scheme. In the generic communication module, it is about the initialization procedure for the CAN controller, receiving message procedure, sending message procedure, error procedure and interrupt service routines. In the motion control application module, it concentrates on the issues of outputting control messages and inputting status messages.The author developed the software applications, and designed some test cases for the communication system. Finally, The author made the tests about the generic communication capabilities on the system simulation test platform. The results proved that the communication system fundamentally met the requirements of the original design.