Design And Implementation Of ProtocolAnalysis System For Various NC Field-bus

Reliability and real-time performance are outstanding advantages of CNC field-bus.Fieldbus has become an important part of CNC machine tools. There are many kinds offield-bus-technologies now. Ethernet-based fieldbus technologies were widely used inCNC and servo products.If real-time or synchronization issues occurred on the field-bus system, numericalcontrol system wouldn’t operate reliably, and the CNC couldn’t meet the design targetsor even lead to accidents. The cycle and response time are very important to thedevelopment process and fault detection. There is no mature protocol analysisequipment for domestic field-buses now. That is a serious problem and became ahotspot in numerical control domain.Foreign manufacturers had developed special devices for their field-buses. Thesedevices are fully functional, but do not support domestic field-buses. Some domesticanalysis devices support domestic field-buses. However, these devices just support onlyone of these buses.The main technical difficulty in design of fieldbus analysis system is how tocapture the data in real time. The acquisition time must be measured accurate andcannot be affected by the heavy traffic. If the packet acquisition time is not accurate, theanalysis system is useless.To solve this problem, this paper designed a multi-protocol fieldbus analysissystem. Because mainstream field-buses are based on the Ethernet, their packetstructures are similar. This paper proposes a method to describe packet structures withXML language. Analysis system can support NCSF and EtherCAT by dynamicconfiguration method. RTAI and Shared Memory Technology were used to make surethe real-time performance.This system has been tested on a CNC system based on NCSF. Experimental dataproved that the system is reliable and stable. System can collect data in real time andparse packets according to the XML files. The system can measure cycle length andflow. System had achieved the expected goals.