| Kinds of Field-bus Control System have come into being since 1980's. However, systems consisting of different bus protocols can not communicate with each other, which impedes users' selection. With the rapid development of Ethernet technology, Ethernet protocol has already become a standard factually and industry Ethernet has been applied to control fields. How to integrate Ethernet and Field-bus Control System is extremely important to the future of kinds of Field-bus Control System.In addition, the integration method between Ethernet and Field-bus Control System has become a hotspot to those who want to enter industry control area.Based on these factors, we designed a system which integrates some protocols. This system can communicate with ModBus, PPI, CanOpen and TCP/IP protocol. For one thing, as a node of PPI, ModBus and CanOpen bus, it can analyze data stream among these buses; for another, it can realize data communication and shareing between buses; moreover, it can also provide an Internet interface to meet the requirement of remote-monitoring.This paper has introduced hardware and software design for the system. The hardware consists of main-control CPU module, RS232/RS485 module and CAN module. A 100M MCU is embedded in the main-control module which can provide hardware and software interface to another module. In addition, communication between buses is implemented in this module. The task of RS232/RS485 is to realize signals conversion between RS232 and RS485.Functions of CAN module is to realize CAN2.0 physics-Links protocol.The software of the system is realized by a method of layering. It is divided into hardware-drive layer, protocol-layer and application layer. Accordingly, each layer has a data buffer. Data are exchanged between layers by buffers. Data are flowed from the protocol buffer to the hardware buffer at the time of sending data. On the contrary, Data are transmitted from the hardware buffer to the protocol buffer when receiving data.This system supports Modbus, PPI and CanOpen protocol. Users can configure the protocol freely according to their requirement. Two methods are provided in thesystem configuration, which are hardware configuration and software configuration. Communication between protocols is realized by a method of sharing addresses. This paper introduces three methods of sharing addresses, which are true address shared by polling, virtual address shared by incident and virtual machine.At last, this paper introduces a system in reality application and some new products derived from the project. |
