Design And Application Of Protocol Converter Based On Fieldbus

Fieldbus technology has been widely applied in all aspects of industrial productionand social life. To some distributed control systems, using only one kind of fieldbus maynot satisfy the demand of communications. However, different Fieldbus can notcommunicate directly. To solve the problem, this thesis designs a bus protocol converteraccording to practical demands, which can realize the communication between CAN busprotocol and Modbus protocol. The thesis gives a brief introduction of communicationmechanisms, reference model, packet format, frame structure and error check about thetwo protocols based on reading a lot of related literature and also gives resolved plans.The thesis deeply analyzes the characteristics of the two protocols, and thenintroduces the solutions of software and hardware design in detail. Software design ofsystem including: software design of PC, software design of protocol converter, softwaredesign of two CAN sub-node and error check. The servo control monitor interface thatpreviously designed by VC++6.0based on Modbus protocol is considered as the Modbusmaster station. It mainly contains functions such as online parameter setting andmodifying, data storage and processing, list display etc. The protocol converter isconsidered as a slave station. Its task is to complete the transformation of the Modbuspackets and CAN packets. The hardware design mainly includes protocol convertermodule, the Modbus interface module, CAN-bus interface module and power module etc.The test results of three function codes of Modbus protocol show that the design ofthis thesis is rational and valid. The idea of protocol conversion has been fully applied inthe oil logging project. The task of data collection and network monitoring is doneperfectly too.