Development Of POWERLINK Slave Station Based On RT-thread

With the development of industrial automation, the field production system has increasingly higher demand on data communications technology. As one of the kinds of mainstream Real-time industrial Ethernet, POWERLINK is a kind of open source technology. It can be applied in a variety of hardware platforms, and has high speed data acquisition and transmission, flexible topological structure, large data throughout and so on. Based on the above reasons, POWERLINK has a wide range of application prospects. A development scheme of slave station based on the RT-Thread real-time operating system is studied. The POWERLINK protocol stack is implemented in the form of hardware in this scheme. This scheme has hard real-time performance, and reduce the burden on the system when the POWERLINK protocol stack is running. The main contents of this thesis are as follows:Combined with the development trend of POWERLINK protocol stack and considering the requirements of communication performance in the industry control field, the hardware platform of POWERLINK slave station based on the RT-Thread real-time operating system is developmented to improve the communication performance and reduce the burden on system.The overall structure of the hardware protocol stack is studied. The three key parts of the hardware protocol including the medium access controller, the network state machine of the protocol stack, the synchronization module are especially analyzed. In order to meet the requirements of the high speed communication, a method is proposed to cache the data. By arranging the data frames not needed by application layer in different positions, the covering of data frames needed by application layer can be avoided.Combined with the features of Cortex M3 kernel, the porting of RT-Thread operating system is studied. The threads of the software are designed, and the privilege of the threads is arranged according to the requirements from process data communication and service data communication on real-time performance. The construction method of object dictionary is studied, by setting the index table, the time required to find object is reduced. The interfaces for object dictionary are specially designed for the requirements from process data communication on real-time performance.In order to verify the communication functions of slave station, and get the operating parameters, the tests for communication functions and performance, and the test for interoperability have been done. The results show that the slave station has normal communication function, and has better performance than any other implementing methods, indicating that the proposed methods are effective.