Online Tool

Modbus Frame Decoder / Encoder

Decode or build Modbus RTU/TCP frames: function codes, registers, coils, MBAP header, and CRC/LRC validation online.

Raw HEX Frame Input

Protocol Mode

Request Frame (optional)

Start Address (optional)

Display Format

Cleaned chars: 0

Bytes: 0

Live decoding enabled

Modbus Frame Generator

Mode

Slave / Unit ID

Function Code

Start Address

Quantity

Single Value

Values (comma-separated)

Diagnostic Sub-function

No hex pasted yet. Try Sample to see the decoder in action.

About this tool

Decode raw hex captures (Wireshark, serial sniffer, SCADA gateway logs) field by field — no sign-up, no uploads, everything runs in your browser. Supported input formats:

Spaces, commas, colons, newlines, 0x prefixes, mixed case hex.
Single frame or concatenated frames; the first complete frame is decoded.
Click Sample for a realistic frame typical of this protocol.
All parsing is local (no network calls, no telemetry).