| There are numerous small and medium enterprises in our country, and they are generally facing the problem of poor technology, insufficient fund and low automatic level. So low cost solution becomes the choice of many enterprises. The cost of traditional solution with industrial computer is relatively high, but with embedded technology, the whole cost of industrial automation system can be lowered effectively while meeting the control request, and it is meaningful for improving enterprise's economic benefits.By analyzing the demand of small-scale industrial process control system , the article designs the framework of the control system, and develops the hardware system of the controller. The central control CPU adopts high-performance embedded processor. To simplify the bus interface, SMBus is adopted to realize the interconnection between CPU board and other function card .The software system of controller adopts the embedded real-time operating system uC/OS-II as the running environment of application tasks. On the one hand it could make full use of CPU, on the other hand it greatly simplified the software development and the future maintenance. For the requirement of network communication protocol, the memory manager and the system timer manager is extended. Timer manager has several kinds of precision timers, and it simplifies the complexity of timing event process.In order to meet the requirement of control layer's network bandwidth , the network connection between the field controller and the supervisory host computer adopts Ethernet network, and the network communication protocol of the upper layers uses TCP/IP. On the basis of in-depth research of TCP/IP protocol stack, the part that is not needed in the system is eliminated, and some protocol's realization is simplified, those changes make the protocol more adaptive to the embedded environment. With Ethernet and TCP/IP protocol , supervisory control computer can easily control the field controller.
|
PDF Full Text Request