Fieldbus is a kind of full digital, bi-directional and multi-station communication net between field intelligent instruments and automation control systems in industry. It is a convergence of processing control technology, industrial automation instrument technology and computer network technology. Which will lead to occur a renovation in control systems. As a kind of open, digital, bidirection, multistation communication system, fieldbus has been developed and applied greatly in many fields in recent years. But, up to now, the international standard for fieldbus has not been setup and the products from different companies use their own field bus system. In this case, to solve the multifieldbus technology in a distribution system becomes a key problem for application of fieldbus.
With the wide application of single—chip computer and computer in the industrialcontrol field，the communications between them have become an important research subject inmodem industrial control system . Especially，in the case of remote control， the remote
communication between them is the base and prerequisite of operation and work .
In this paper we discuss the details of communication between microcomputer and MCS-51 single-chip computer by using VB, and give the source program and its flowing chart. The communication protocols are explained. The system structure charts and the circuit of hardware are given.Keywords：Fieldbus ；Serial communication；MCS-51 single-chip computer；RS-232；RS-485； VB6.0 ；MSCON；communication control
