Implementation Of Wireless HART DLL Protocol And Research On Time Synchronization Technology

There is an increasing need for wireless sensor network with the rapid development of sensor technology, micro systems technology, wireless communication technology, and computer technology. Industrial wireless network, which is based on wireless sensor network, expends and upgrades the functions of industrial communication technology. It becomes another research topic after field bus technology. Wireless network communication protocol in the industrial field includes HART7.1, ISA100 and WIA-PA of China. Wireless HART is a wireless network communications protocol, designed to meet the needs of process automation applications. It provides a guarantee for the industrial areas to implement intelligent low-cost wireless communication because of its safety, reliability and compatibility.At the beginning of the thesis, the developing environment of wireless HART communication protocol and software architecture design are introduced. Wireless HART layers, the message and the management service primitives between layers are analyzed in detail. What's more, the task priority of Protocol layer and the information interaction between layers are also confirmed. The thesis puts emphasis on the software implementation of wireless HART physical layer and data link layer. Since the time synchronization is one of the key technologies in wireless sensor network, and it is achieved in data link layer of wirless HART, the thesis also focuses on time synchronization technology. The work is divided into the following three parts:(1) On the basis of protocol software architecture, the physical layer of wireless HART is designed and implemented. It includes the definition of variable and the processing of the primitive and background tasks. The physical achieves a transparent transmission of the bit Stream, and provides message services and management services for data link layer.(2) On the basis of physical layer, the data link layer of wireless HART is designed and implemented. It includes the variable definition, the processing of the primitive and background tasks, the state machine realization, the link schedule, the time synchronization, et al. The data link layer achieves correct conversion of state by state machine, and realizes the link schedule and the time synchronization. It ensures secure, reliable and error free communication, and provides message services and management services for network layer.(3) A time synchronization method based on clocked-loop adjustment strategy is proposed and realized in wireless HART protocol. The proposed method gains the time offset model parameters in synchronization by measuring the time offset between the synchronization nodes, creates an internal model of the controlled object and achieves short cycle closed-loop adjustment of time offset. It provides guarantees for data communication, localization, data fusion and so on.The physical layer and data link layer are tested on the CC2430 communication modules. The results show that the data link layer ensures secure, reliable and error free communication and provide good services for network layer on the basis of physical layer. The time synchronization method is tested by Matlab and CC2430 communication modules. The results show that CATS achieves higher synchronization accuracy, stronger environmental adaptability, and lower computational complexity. Thus it provides a program for wireless HART time synchronization in complex industrial field.Overall, this research work establishes a good foundation for the next wireless HART protocol stack development.