Modbus Frame Analyzer
Frame Input
Analysis Results
Enter a Modbus frame in hex format and click "Analyze Frame" to get detailed analysis.
Tips:
- Request Mode: Shows detailed field breakdown with descriptions
- Response Mode: Interprets data payload as integers, floats, or raw hex
- Data Formats: Int16 (2 bytes), Int32/Float32 (4 bytes each)
About Modbus RTU
Modbus RTU is a serial communication protocol that uses binary representation of data. Each frame contains:
- Slave Address: 1 byte (1-247)
- Function Code: 1 byte
- Data: Variable length
- CRC: 2 bytes (error checking)
Common Function Codes:
- 0x01 - Read Coils
- 0x03 - Read Holding Registers
- 0x06 - Write Single Register
- 0x10 - Write Multiple Registers
About Modbus TCP
Modbus TCP is an Ethernet-based protocol that encapsulates Modbus data. Each frame contains MBAP header:
- Transaction ID: 2 bytes
- Protocol ID: 2 bytes (always 0x0000)
- Length: 2 bytes
- Unit ID: 1 byte
- Function Code + Data: Variable
Example Frames:
- RTU Request: 01 03 00 00 00 0A C5 CD
- RTU Response: 01 03 14 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 B8 44
- TCP Request: 00 01 00 00 00 06 01 03 00 00 00 0A
- TCP Response: 00 01 00 00 00 17 01 03 14 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Data Interpretation Formats
HEX
Raw byte values displayed as hexadecimal.
16-bit Integer
Each pair of bytes interpreted as unsigned 16-bit integer (0-65535).
32-bit Integer
Each group of 4 bytes interpreted as unsigned 32-bit integer.
32-bit Float
Each group of 4 bytes interpreted as IEEE 754 floating-point number.