The Development Of Multi-protocol Communication Converter In Industrial Control

Presently,in an industrial control network,every device's interface is more and more sophisticated,and communication with different devices is increasingly difficult in that the devices often use different bus interfaces and run different application layer protocols;standard or non-standard on their own buses.Accordingly,it is of practical significance to develop a software and hardware protocol converter with strong compatibility which can meet the needs of different bus interfaces and different application protocols.First,to fill up the traditional RS485 conversion CAN protocol converters' deficiency,namely,long response time,single forwarding mode and low adaptability to specific industrial sites,we present in this paper three protocol forwarding modes for different needs: transparent transmission,packet forwarding,storing and forwarding.Second,taking into consideration the often-used bus standards and the upper application protocols in industrial control network,we design a multi-application protocol interconnection gateway which can support both CAN bus and RS485 bus and accomplish,based on an analysis of different buses and application protocols,the development of the embedded gateway's software and hardware.In our study,we took Cortex-M0 series LPC11C14 as the control center of our protocol converter,and have completed the design of the CAN interface module,RS485 interface module,power supply circuit module and other hardware.On the basis of this,we have then finished the software system design of the main program module,CAN communication module,and RS485 communication module.Among the software systems,the main communication module primarily is responsible for multi protocol conversion,and three data forwarding modes;CAN communication module realizes its multi-protocol communication by studying hardware protocol,CANopen protocol and iCAN protocol;RS485 communication module realizes its multi-protocol communication by studying hardware protocol,Modbus RTU protocol and Modbus-ASCII protocol.Besides,we have had the conformance testing on the protocol converter,the result of which has proved the reliability and validity of it.Now the protocol converter has been applied to the excitation control system,and not only satisfied the needs of protocol conversion,but also extended communication distance effectively.