Function Codes

Understanding MODBUS-RTU Protocol: Mastering Industrial Communication with Four Core Function Codes (01/03/05/06)

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Understanding MODBUS-RTU Protocol: Mastering Industrial Communication with Four Core Function Codes (01/03/05/06)

In the field of industrial control, MODBUS-RTU is one of the most universal and time-tested communication protocols. It acts like the “Mandarin” among devices, allowing instruments, PLCs, and controllers from different manufacturers to communicate smoothly. Today, I will set aside complex theories and directly guide you through the four most commonly used function codes:01, 03, … Read more

Modbus Protocol 4 — Function Codes (Part 2)

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Continuing from the previous introduction of function codes, Function Code 02 Function Code 02 indicates reading the status of discrete inputs. Request Message Format Function Code (1 Byte) Starting Address (2 Bytes) Quantity (2 Bytes) 0x02 0x0000 – 0xFFFF 1 – 2000 Normal Response Message Format Function Code (1 Byte) Byte Count (1 Byte) Discrete … Read more

Modbus Protocol 3 – Function Codes (Part 1)

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Function Codes In Modbus communication, function codes are a core issue, with each function code representing the action to be executed by the message. The commonly used function codes are defined as follows: Function Code Name Purpose 01 (0x01) Read Coils Read the status of one or more coils 02 (0x02) Read Discrete Inputs Read … Read more

Modbus Protocol 2 – Modbus RTU

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Modbus RTU Modbus RTU is a communication protocol used between industrial electronic devices. The main features are: Used in a master-slave network architecture, with one master and multiple slaves, up to 247 slaves. Physical communication lines, typically RS485 or RS422. The master is responsible for message requests, while the slaves respond to these requests, hence … Read more

Modbus Function Codes: Definitions, Applications, and Selection Considerations

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Modbus Function Codes: Definitions, Applications, and Selection Considerations

In the field of industrial automation, the Modbus protocol has become the core standard for communication between devices due to its simplicity and wide compatibility. The Modbus function codes serve as the “instruction set” of the protocol, defining the types of commands between master and slave devices and determining the specific operations performed by the … Read more

Detailed Explanation of Modbus Protocol and Data Types

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Detailed Explanation of Modbus Protocol and Data Types

Click 👆 above to follow Engineer Yan Ji and ★star★. Protocol Definition 1. Modbus is a request-response protocol implemented using a master-slave relationship. 2. The Modbus protocol introduces different application data units to change the packet format used in serial communication or to allow the use of TCP/IP and User Datagram Protocol (UDP) networks. Its … Read more