Modbus ASCII Online Tool | Modbus ASCII Frame Parser/Command Generator/LRC Checker/Data Converter
Modbus ASCII online tool supporting ASCII frame parsing, command generation, response data/frame generation and LRC checking. Supports multiple data types (UINT16/INT16/UINT32/INT32/FLOAT32) and byte orders (ABCD/DCBA/BADC/CDAB), one-click generation of standard Modbus ASCII commands.
Modbus ASCII Command Generator
Modbus LRC Checksum Calculator
Modbus ASCII Response Generator
Modbus ASCII Message Parser
Parse Rules Configuration
User Guide
Function Overview
Modbus ASCII Tool is an integrated Modbus ASCII protocol tool that provides three core functions: command generation, response data generation, and data parsing. It helps users quickly generate standard Modbus ASCII commands, simulate slave response data, and parse actual communication data.
Main Features:
- Command Generation: Supports common function codes, can quickly generate standard Modbus commands
- Response Data Generation: Supports simulating slave response data for testing and verification
- Data Parsing: Supports parsing multiple data types and byte orders, can quickly verify if data types and byte orders are correct
Command Generator User Guide
- Slave Address: Device hardware address, range 0-255
- Function Code: Supports standard function codes like 01/02/03/04/05/06/15/16
- Start Address: Starting address of registers 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 Data Generator User Guide
- Select function code matching the command
- Supports multiple data types: UINT16/INT16/UINT32/INT32/FLOAT32 etc.
- 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 User Guide
- Supports inputting standard Modbus data frames for parsing
- Can configure multiple parsing rules, supports different data types and byte orders
- Built-in multiple data type conversions, supports signed/unsigned integers and floating-point numbers
- Flexible byte order configuration, adapts to different device data formats
- For parsing large amounts of data, it is recommended to use the file parsing function in the Modbus data parsing section of the Modbus debugging page, which supports batch data processing
Modbus ASCII Protocol Knowledge
What is Modbus ASCII?
Modbus ASCII is the ASCII transmission mode of the Modbus protocol, using readable ASCII characters to transmit data, starting with a colon, ending with carriage return and line feed, using LRC checksum.
Protocol Features
Modbus ASCII protocol is easy to debug and analyze, data is transmitted in readable ASCII characters. Although transmission efficiency is lower than RTU mode, it is convenient for manual viewing and debugging.
Communication Principle
Modbus ASCII uses master-slave communication, data frames start with colon (:), end with carriage return and line feed (\r\n), using LRC checksum to ensure data integrity.
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)
- 64-bit Unsigned Integer (0-18446744073709551615)
- 64-bit Signed Integer (-9223372036854775808 to 9223372036854775807)
- 64-bit Float (IEEE-754 Double 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
- Pay attention to CRC/LRC checksum results
- Set data types and byte orders properly
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