Modbus RTU Online Tool | Command Generation/Response Generation/Data Analysis All-in-One Tool

Professional Modbus RTU online tool with three core functions: command generation, response data generation, and data analysis. Supports multiple data types (UINT16/INT16/UINT32/INT32/FLOAT32) and byte orders (ABCD/DCBA/BADC/CDAB).

Command Generator

03 - Read Holding Registers
Generate CRC Checksum

Data Generator

03 - Read Holding Registers
Data Type
Byte Order
Value(Decimal Value)

Data Parser

Parse Rules Configuration

Start PositionData TypeRaw DataByte OrderOrdered DataParse ResultActions

User Guide

Overview

Modbus RTU Tool is an integrated Modbus RTU protocol tool that provides three core functions: command generation, response data generation, and data parsing. It helps users quickly generate standard Modbus RTU commands, simulate slave station responses, and parse actual communication data.

Main Features:

  • Command Generation: Supports common function codes for quick generation of standard Modbus RTU commands
  • Response Data Generation: Supports slave station response simulation for testing and verification
  • Data Parsing: Supports parsing of various data types and byte orders for quick verification of data type and byte order correctness

Command Generator Guide

  • Slave Address: Device hardware address, range 0-255
  • Function Code: Supports standard codes 01/02/03/04/05/06/15/16
  • Start Address: Starting register address to access
  • Quantity: Amount of data to read or write
  • Common Command Examples:
  • Read Holding Registers: 01 03 00 00 00 02 C4 0B (Read 2 registers)
  • Write Single Register: 01 06 00 00 00 01 48 0A (Write value 1)

Response Generator Guide

  • Select function code matching the command
  • Supports various data types: UINT16/INT16/UINT32/INT32/FLOAT32
  • Supports multiple byte orders: ABCD/DCBA/BADC/CDAB
  • Response Data Examples:
  • Read Response: 01 03 04 00 01 00 02 2A 32 (Returns 2 register data)
  • Write Response: 01 06 00 00 00 01 48 0A (Write confirmation)

Data Parser Guide

  • Supports parsing of standard Modbus RTU data frames
  • Configure multiple parsing rules, supporting different data types and byte orders
  • Built-in data type conversions, supporting signed/unsigned integers and floating points
  • Flexible byte order configuration, adapting to different device data formats
  • For parsing large amounts of data, we recommend using the file parsing feature in the Modbus Debug page's Modbus Data Parser, which supports batch data processing

Modbus Protocol Knowledge

What is Modbus?

Modbus is a widely used industrial communication protocol developed by Modicon (now Schneider Electric) in 1979. It has become the de facto standard for communication between industrial electronic devices.

Protocol Features

Modbus protocol is simple, open, and free, using master-slave architecture, supporting multiple data types and transmission methods, widely used in industrial automation.

Communication Principle

Modbus RTU uses master-slave communication, where the master sends commands and slaves respond with data. Each command and response contains slave address, function code, data, and CRC verification to ensure communication reliability.

Supported Data Types

  • 16-bit Unsigned Integer (0-65535)
  • 16-bit Signed Integer (-32768 to 32767)
  • 32-bit Unsigned Integer (0-4294967295)
  • 32-bit Signed Integer (-2147483648 to 2147483647)
  • 32-bit Float (IEEE-754 Single Precision)
  • Each data type occupies different bytes: 16-bit types use 2 bytes, 32-bit types use 4 bytes
  • Different data types for different scenarios: integers for counting and status, floating-point for analog values
  • Pay attention to range limits and precision loss during data type conversion

Byte Order Types

  • ABCD: Big-endian, high byte first (e.g., Siemens devices)
  • DCBA: Little-endian, low byte first (e.g., Intel devices)
  • BADC: Big-endian, byte swap
  • CDAB: Little-endian, byte swap
  • Byte order selection depends on device hardware architecture and manufacturer
  • Incorrect byte order leads to parsing errors, especially in 32-bit data types
  • Confirm device byte order settings before debugging communication

Function Code Description

  • 01/02: Read Coils and Discrete Inputs for switch status data
  • 03/04: Read Holding and Input Registers for analog data
  • 05/06: Write Single Coil and Register for single point control
  • 15/16: Write Multiple Coils and Registers for batch control
  • Custom Function Codes: Support for special devices and vendor protocols

Debugging Tips

  • Use Command Generator to build standard command frames
  • Use Response Generator to simulate slave devices
  • Use Data Parser to verify communication data
  • Check CRC verification results
  • Set appropriate data types and byte orders

Application Scenarios

  • Industrial Automation Control Systems
  • Remote Monitoring and Data Acquisition (SCADA) Systems
  • Smart Instrument Communication
  • Programmable Logic Controller (PLC) Communication
  • Industrial Field Device Debugging and Maintenance
  • Communication Protocol Analysis and Troubleshooting
  • Device Interoperability Testing
  • System Integration Debugging
  • Industrial IoT Data Collection
  • Industrial Equipment Remote Monitoring
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