Table of Contents Introduction: Why OPC UA Became the "Standard Language" of the Industrial Internet Era Background and Development History of OPC UA 2.1 The Birth of OPC Classic 2.2 The Proposal and Vision of OPC UA 2.3 International Standardization and Ecosystem Development Overall Architecture of OPC UA 3.1 Future-Oriented Cross-Platform Architecture 3.2 Communication Stack Structure 3.3 Information Model and Data Organization Core Technical Features of OPC UA 4.1 Security

Table of Contents What is the MQTT Protocol? 1.1 MQTT's Design Philosophy & Key Features 1.2 Why is MQTT Indispensable in IoT/IIoT? Basic Principles and Workflow of MQTT 2.1 Publish/Subscribe Pattern: Evolution from IBM MQ Series 2.2 Detailed Explanation of MQTT Packet Structure 2.3 MQTT 3.1, 3.1.1, 5.0: Version Differences & Migration Guide 2.4 MQTT Application Scenarios in IoT (Modbus/MQTT/OPC UA Integration Explained) Detailed Understanding of MQTT Protocol Architecture 3.

Table of Contents Introduction: Why Has Modbus Survived for 40 Years? The Historical Background and Development of Modbus 2.1 Birth Background 2.2 Evolution 2.3 Why Has Modbus Not Been Phased Out? Modbus Protocol Architecture 3.1 Basic Architecture 3.2 Data Model Three Major Modbus Variants: RTU / ASCII / TCP 4.1 Modbus RTU (Most Classic and Common) 4.2 Modbus ASCII (Early Version) 4.3 Modbus TCP (Ethernet Version) Modbus Frame Structure and Function Code Details 5.1 Modbus R