用单片机设计现场总线，实现通信协议。本课程设计是基于51单片机构成的下位机通讯，按照一定的总线协议，通过串口与微机通讯。设计主要实现微机对下位机的查询和设置参数的功能。微机可以查询到下位机的地址号，量程上下限的值，报警上下限的值，以及对下位机地址号的设置，对量程上下限的设置，对报警上下限的设置，并可以实时的查询修改后的参数值。-

By single chip design field bus, realize communication agreement. This course design is based on 51 single-chip computers.the lower place machine communication, according to certain bus agreement, through a serial port to the computer. Design mainly realizes the microcomputer to lower place machine of the function of the parameters set and inquires. Microcomputer can inquires under the address of the machine to a number, the lower range of value, the value of the lower limit alarm, as well as to a machine, under the Settings of the address, the range of the lower limit on set, on the setting of the lower limit of alarm, and can real-time inquires the modified parameter values.