Result stream
Decoder highlights
• Register Diagnostics accepts raw register frames with spaces/commas, converting each word to unsigned, signed (two's complement), and scaled engineering values. • Frame Analyzer ingests RTU or TCP captures, validates CRC/MBAP headers, and breaks out address/function/data sections. • Direction tabs keep workflows separate while sharing the same result stream and insights.
About Modbus RTU
RTU frames are serial and binary: Slave Address (1 byte), Function Code (1 byte), Data (variable), and CRC16 (2 bytes). Common functions include 0x01 Read Coils, 0x03 Read Holding Registers, 0x06 Write Single Register, and 0x10 Write Multiple Registers. CRC validation confirms line integrity before trusting payloads.
About Modbus TCP
TCP encapsulates Modbus data with the MBAP header: Transaction ID (2 bytes), Protocol ID (0x0000), Length (2 bytes), Unit ID (1 byte) followed by Function + Data. The tool surfaces each MBAP field so you can verify routing IDs alongside the actual application payload.
Example frames
RTU Request: 01 03 00 00 00 0A C5 CD | Response: 01 03 14 00…B8 44 TCP Request: 00 01 00 00 00 06 01 03 00 00 00 0A | Response: 00 01 00 00 00 17 01 03 14 00…00.
Data interpretation formats
Use the Data Interpretation selector to treat payload bytes as Hex, Int16 (2 bytes), Int32 (4 bytes), or 32-bit IEEE floats. The analyzer groups bytes accordingly and reports decimal values so you can quickly spot engineering limits or swapped byte orders.