Protocol Anatomy Guide

Master the interactive byte-level explorer. Click, filter, deep dive, and export UDS protocol messages like a pro.

1. The Byte Canvas

Every UDS message is visualized as a row of color-coded byte modules. Each module represents one or more bytes of the protocol frame.

🔵 Cyan — SID

The Service Identifier. Always byte 0.

🟣 Purple — Sub-function

Operation modifier (e.g., session type, reset mode).

🟢 Green — Data

Data identifiers, addresses, and payload bytes.

🟡 Amber — Parameter

Timing values, format specifiers, and optional fields.

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Try it: Click any byte module below to expand its details panel. Click again to collapse.

2. View Modes

Toggle between three viewing modes using the control in the top-right corner:

⧉ Split — Side-by-side Request and Response (default)
→ TX — Request bytes only
← RX — Response bytes only

3. Alternative Value Explorer

Some bytes have multiple valid values (alternatives). When you click a byte with a purple dot, the details panel shows all possible values.

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Click an alternative to see the hex value morph live in the byte canvas. Click the original value or the ”↺ Reset to default” button to revert.

4. Semantic Filter

The filter toolbar lets you highlight specific byte types. Click a filter chip to dim all non-matching bytes, making it easy to focus on just the SID, sub-functions, or data fields.

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Click the same chip again to deactivate the filter and show all bytes.

5. Deep Dive Modal

When a byte has enriched data (ISO references, usage notes, related services), the details panel shows a “Deep Dive ↗” button. Clicking it opens a full modal with three tabs:

ISO Spec — The exact section reference from ISO 14229-1:2020, usage notes, and a metadata grid
Code — Copy-paste code snippets in TypeScript, Python, and C for constructing this byte
Related — Links to related UDS services and common usage patterns

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Press Escape to close the modal, or click the backdrop.

7. Live Example

Here’s a fully interactive Protocol Anatomy for SID 0x10 — Diagnostic Session Control. Try all the features described above: