Research And Development Of MMI Software Based On Lonworks Fieldbus Control System

An MMI(Man Machine Interface) software of the measurement and control system basedon LonWorks(the trademark of Echelon Inc.) Filedbus is developed and studied. TheLonWorks system has the network architecture of two layers, the bottom layer LonWorksFieldbus and the top layer Ethernet. The MMI software has the following functions,the control and configuration of nodes, the data communication, the OPC(Ole forProcess Control) standard software interface, the data distribution on web , thedisplay of data and pictures, the data store. The MMI software mainly consists of two components. One is the software of theintelligent nodes for controlling the devices. The other is the software of systemfor controlling the system data communication and the devices configuration . Thepart for the AI,DIO,TC,RTD,PID,RTC and TCC nodes has been developed by Neuron c.TheLonTalk is used as the protocol of data communication. And the structure of the datainterface of the PC is based on the LNS(LonWorks Network Service) of the Echelon.The system configuration and data communication are implemented .The configurationand monitor software has been developed by VB6.0. The software has been used in thefactories. A solution for building a Data Access OPC Server is proposed which solve theproblems in the developing procedures and gives out a reliable and efficient OPC Server.The Data Access OPC Server for the system increases the range of the systemapplication and compatibility. The server is in accord with the OPC standard,implementing the custom interfaces of the Data Access OPC Server. The implementationincludes the OPCServer, OPCGroup and OPCItem Objects. The data communication betweenthe Server and the clients, especially asynchronization communication, is achived.The OPC Client software developed by VC6.0 is used for testing the OPC Server andbuilding the configuration and monitor program. The OPC Clients software inquiry theOPC Servers in the local and remote machines and read and set the data and datastructure of the OPC Servers. The methods for building the Web interface by ISAPI and building the configurationand monitor software are also discussed. Through testing the laboratory and factory implementations, the software has beenproved to be credible. Thus the entire design scheme and the developing methods arevaluable.