Modbus specification document and implementation guide
The following document is officially released by the Modbus Organization and is the authoritative technical specification for the Modbus protocol. Modbus Chinese website provides complete Chinese translation and English original PDF, both of which can be downloaded directly.
This document is the Modbus Application Layer Protocol Specification V1.1b3 version. The document provides a detailed description of all function codes used in the Modbus transaction processing framework, including core content such as request/response message formats, data encoding methods, and exception code definitions. This is the most fundamental and important specification document for the Modbus protocol.
The Modbus security protocol provides security protection by integrating Transport Layer Security (TLS) with the traditional Modbus protocol. TLS encapsulates Modbus packets to achieve identity authentication and message integrity protection. The protocol also utilizes X.509v3 digital certificates for identity authentication of servers and clients. The Modbus security protocol uses port 802 for communication.
Modbus serial line specification (old version, for legacy systems only)
Original English version Chinese translation versionThis is the obsolete Modbus serial line specification released in 1996. Only used to solve compatibility issues with legacy systems, do not use for the development and implementation of new projects. Please use the "Modbus Serial Protocol and Implementation Guide V1.02" below for new projects.
Modbus Serial Protocol and Implementation Guide V1.02
Original English version Chinese translation versionThis is the latest specification document for Modbus serial communication, covering all aspects such as RS-232/RS-485 physical layer, frame format, master-slave addressing, timeout mechanism, etc.Please make sure to use this specification for the new Modbus serial line implementation.
The Modbus Message Implementation Guide V1.0b version is provided by Schneider Automation. This document aims to provide reference information for software developers who implement Modbus messaging services, providing accurate and comprehensive descriptions of the implementation of Modbus messaging services, with the aim of promoting interoperability between devices using Modbus messaging services. This document does not contain encoding descriptions for all Modbus function codes. Please refer to the Modbus application layer protocol specification for relevant information.
The Modbus message implementation guide includes the following three parts:
- Overview of Modbus over TCP/IP
- Functional description of Modbus client, server, and gateway implementation
- Modbus Implementation Example (Propose Object Model)
In addition, it also includes the "Modbus TCP Protocol Object Message Specification" section.
Modbus TCP Protocol Object Message Specification
Original English version Chinese translation versionObject Message Protocol for Modbus TCP, used as a component of the SEMI Sensor Bus Network Communication Standard (NCS). SEMI is a global semiconductor industry association that defines the standard for using Modbus TCP for sensor communication in semiconductor manufacturing environments.
