Network Discovery Research And Implementation Of The Agreement And Clock Synchronization Protocol. Lxi Instruments

With the develeopment of science and technology,testing task is increasingly complex and the geographical distance of DUT(Device Under Test) is longer and longer.So the role of distributed automatic test system is more and more important.Ada- pting to this tendency,Aglient Technology and VXI Technology,Inc. introduced the new generation instrumentation bus-LXI(LAN eXtension for Instrumentation).The architect- ure of LXI is openly,and it provides very convenient conditions for building distributed automatic test system due to its flexible packaging.Meanwhile, hybrid test system combined by LXI and other instrumentaion bus provides a convenient and flexible solution for testing complex DUT.The tast is to design a logic analyzer based on LXI bus with highest sampling rate of 500MHz,64 data channels.Its software modules include LAN discovery,clock synchr- onization,IVI-COM and VISA driver interface ,web pages and so on.However,the main issue of this paper is to research on LXI's LAN discovery(VXI-11 protocol) and clock synchroniztion after introducing the trend of LXI development.LAN discovery is LXI's base function.Moreover,in the structure of driver interfa- ce,it plays the role of communicating upper driver interface with LXI instruments.After LAN discovery protocol was researched,Netbula RPC library was used to realize LXI's LAN discovery in this paper.And then,its limitations were analyzed.Lastly,RPC library was designed by ourselves and LXI's LAN discovery was achieved by using our RPC library.And the limitations of using Netbula RPC library were solved by this plan.Clock synchronization must be implemented in LXI Class-A and Class-B instru- ments.However,the high-precision clock synchronization is one of difficulties for desig- ning LXI instruments because of network environment.After the clock synchronization protocol was studied, the ideas for realizing IEEE1588 precision clock synchronization protocol were explained in this dissertation.Then, the implementation of clock state machine and best master clock algorithm was described.And the time for calling best master clock algorithm was optimized.At the same time,the software module of clock synchronization was designed in two different plans and the results of clock synchroniz- ation experiments were analyzed.The results showed that the precision of clock synchr- onization can satisfy the requirements of this task's clock synchronization.Lastly,the prospect to improve the system was put forwarded.