Method and system for realizing Modbus communication on serial link

Abstract

The invention provides a method and a system for realizing Modbus communication on a serial link. According to the invention, control requests of the host to slaves are issued to the slaves in sequence by establishing a message queue, and a second request instruction is issued only after the slaves send back response data, so that only one request transaction is ensured at the same moment under aserial link, and the data is not collided; the states of the host and the slaves are defined, a retry mechanism is matched, a solution is provided when the slaves do not reply, and the problem that the host is always in a response waiting state due to the fact that the slaves do not reply messages in time is solved. The problem of simultaneous control request for the multiple slaves under the serial link is solved; the problems of data loss and data disorder caused by requests for the multiple slaves at the same time are avoided, and the method is suitable for all scenes that the cloud platform controls the multiple slaves on the serial link, such as data acquisition and control based on serial bus Modbus equipment and data acquisition and control based on serial bus ammeter protocol equipment.

Description

Technical field [0001] The invention relates to the application field of Modbus communication technology, in particular to a method and system for realizing Modbus communication on a serial link. Background technique [0002] Modbus protocol is a universal language used in electronic controllers. It was originally developed by Modicon. Now Modbus is the world's most popular protocol in the industrial field. This protocol supports traditional RS232, RS422, RS485 and Ethernet devices. Many industrial equipment, including PLCs, smart meters, etc., are using Modbus as the communication standard between them. Through the Modbus protocol, control equipment produced by different manufacturers can be connected to an industrial network for centralized monitoring. [0003] Modbus serial link protocol is a master-slave protocol. At the same time, only one master is connected to the bus, and one or more slaves are connected to the same serial bus. Modbus communication is always initiated by t...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method and system for realizing Modbus communication on a serial link, aiming at solving the difficult problem of simultaneously controlling multiple slaves under the serial link in the prior art, and avoiding multiple slaves at the same time. The problem of data loss and data confusion caused by computer requests can be solved, and work efficiency can be improved

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