Ethernet Industrial Control Network Communications Applications

In 21 century, Industrial automation system is developing to distributed and intelligentized real-time control. Communication becomes key,The user' s demand to unitive communication protocol and control network is increasingly imminency. The traditional ethernet using in commerce enters control field.Recently industrial ethernet develops rapid, which has quick transmition speed,the same communication protocol, good compatibility, flexible makeup. Industrial control system based on ethernet gradually replaces FCS and becomes the best project of control network.The appliance of control network ethernet of KISCO hot mill control system is researched in the essay. I studies development of ethernet technology,Using the ethernet technology, ethernet can be applied in industrial manufacture. The productive process of hot mill is introduced. APC system, MMI system, network server system and level 2 Alpha computer system constitute hot mill control system by ethernet. The control network is switched network, the switches divide the network' to two segment: C-LAN and M-LAN, becomes redundant loop structure. C-LAN provides communication surrounding for spot control equipment,level 2 computer and operater' s workstation; M-LAN provides communication surrounding for APC programmer computer, level 2 programmer computer and manage information. APC connects network by industrial ethernet I/O chip and coaxial-cable, other systems connect network by network card and UTP, the main of ethernet uses fiber. Control network use UDP/IP protocol, the configer of networked software accords BSD. Communication subsystem of hot mill control system forms special UDP mailbox connected structure, using mailbox and event flag to communicate. Switched technology, high transmitted speed of ethernet,dividing network to decrease communication load, data exchange in UDP, these assure real time when ethernet is applied industrial control communication. Redundant loop structure, industrial ethernet equipment assure stability.I also introduces the function of MMI in windows system. MMI exchanges data with other system in control network by NDE protocol. NDEis a protocol which is designed and amended with UDP and DDE. It is used in hot mill control network. Based on NDE format, UDP/IP messages contained information are transmited in ethernet, all applied program complete connection, formatting data, checking and dealing with the mistake, ending connection. There are two communication methods between MMI and other systemic program: Dynamic Display Communications Method and One-Shot Communications Method.