Protocol scope and method
This is a boundary diagnostic, not a full escape-aware stream reassembler. Confirm escaping and edition rules before trusting a candidate frame.
candidate frame = 5b ... 5d.
Diagnostic scenario
Run the boundary finder on a redacted, sequence-reassembled stream. Treat every 0x5b-to-0x5d range as a candidate, then apply the project escape rules, declared length and check-code validation before accepting it as one exchange message.
How to interpret the result
This utility does not infer missing segments or fully implement every edition escape rule. Embedded marker bytes and capture loss can create false boundaries. Unmatched tail data should be retained until more stream bytes arrive.
Input reference
- Concatenated stream hex
- Example default: Sample input included
Common mistakes
- Using an unredacted production capture with vehicle, credential or network identifiers.
- Accepting marker pairs without declared-length validation.
- Treating a successfully parsed sample as standards compliance or interoperability proof.
Before using the result
- Confirm the protocol edition, transport framing and vendor profile before interpreting fields.
- Validate candidate length and project check code after unescaping.
- Keep a redacted known-good and known-bad sample as a regression pair.
Questions to check during diagnosis
Does the JT/T 809 Frame Boundary Finder leave my browser?
No application upload is used. Avoid putting sensitive production data in shareable URLs.
Is this a standards compliance test?
No. Confirm the edition and vendor profile with licensed documents and your target platform.
Offline diagnostic aid. Verify fields, version and vendor extensions before production use.