Research And Design Of Functional Safety I/O Slave Station Based On EtherMAC

Now,field bus has been fully applied in the control field.On the premise of meeting the basic function,the functional safety of field bus is put forward.The development level of China's domestic field bus system is low,and the field bus products are limited by the functional safety index now.Therefore,studying the functional safety of domestic field bus is necessary and urgent.This study is under "key technology and product development of field bus safety in CNC system".In this thesis,based on functional safety standard IEC 61508 and EtherMAC field bus which has independence intellectual property,a kind of functional safety slave station which is used in CNC feeding machine is designed.The main content includes:analysis of functional safety requirements of CNC feeding machine,functional safety slave station design of security protocols and underlying hardware according to functions and security requirements of CNC feeding machine,functional safety assessment of functional safety I/O slave station.First,the thesis introduces development situation of functional safety,which includes conception,design methods and evaluation calculation methods.Based on analyses of functional safety field bus,disadvantages of domestic field bus are explained and significance of this study is stated.Because the application object of functional safety I/O slave station is CNC feeding machine,it's necessary to analyse working environment and safety requirements of slave station according to functional safety standards.Using risk chart method and risk matrix method to confirm required safety integrity level of CNC feeding machine,which determines the safety integrity level of slave station.In order to satisfy the safety requirements and functional requirements of slave station,underlying hardware should be designed rationally according to technical manuals of microchip.The risk of slave station can be reduced by rational design of EtherMAC communication protocol and error handling mechanisms.Reliability block diagram,fault tree and Markov are used to establish analysis model which can get safety integrity level of functional safety I/O slave station.According to the calculation result,it is judged whether the safety indicator of the designed slave station meets the safety indicator requirement of the CNC feeding machine.And the design of functional safety I/O slave station can be improved based on analysis model.Finally,functional safety I/O slave station is produced.The test result shows the functions of the station can be realized under the premise of satisfying the functional safety.And the safety measures are established to reduce the probability of risk events.Through the work,functional safety I/O slave station used in CNC feeding machine based on EtherMAC is designed,and its functional safety indicators meet the requirements.The thesis provides an important basis for the design of functional safety slave station based on EtherMAC and has an important reference value for the further development of the domestic EtherMAC field bus.