Signal Acquisition Based On Modbus Communication Protocol

Embedded systems can be seen everywhere in people's lives,and its birth and development have greatly promoted the progress of human society.As an important part of the embedded system,the signal acquisition system plays an irreplaceable role in the field of industrial control.However,in the era of rapid technological development,people pay more attention to the realization of functional requirements.However,a variety of buses and bus protocols need to be applied in the signal acquisition system,which makes the development process difficult,poor data readability,and poor secondary development.To solve these problems,a signal acquisition system based on Modbus communication protocol is designed.The Modbus protocol has the advantages of openness,high reliability,scalability,standardization and free of charge,which can effectively solve these problems to a certain extent.According to the basic structure of the signal acquisition system,a mode of cooperation between the upper and lower computers of the monitoring system is designed.First,analyze the system function requirements based on the actual situation,and determine the overall design plan of the system.Between the two lower-level computers,the collected voltage data is transmitted through the CAN bus;between the lower-level computer and the upper-level computer,through the RS-485 interface bus communication based on the Modbus communication protocol;the upper-level computer realizes query and reception through the Modbus debugging wizard software Function of voltage data.The hardware part selects the STM32F103C8T6 industrial control board as the hardware foundation of the lower computer,including four main functional modules:voltage acquisition module,STM32 microcontroller module,CAN bus transmission module and RS-485 interface bus.The programming part focuses on the main subprogram design of these modules.Finally,the results of modular test and system overall test show that the upper computer of the system realizes sending and receiving commands in the format of Modbus communication protocol,and the received voltage data is consistent with the voltage data collected by the lower computer.