DUML frame
這一頁還沒有中文版，以下為英文原文。
Format and CRCs are in Sources/OpenPocketViewCore/DumlFrame.swift (self-tested). Plaintext — no encryption anywhere.
Layout
Section titled “Layout”55 | len | ver/len-hi | crc8(hdr) | sender | receiver | seq:u16le | flags | set | cmd | payload | crc16:u16le| Field | Notes |
|---|---|
| SOF | 0x55 |
| len | frame length |
| ver / len-hi | version packed with length high bits |
| crc8 | CRC of the header |
| sender / receiver | device addresses |
| seq | u16 little-endian |
| flags | see below |
| set / cmd | command identity; see the catalog |
| payload | command-specific |
| crc16 | u16 little-endian |
| Value | Meaning |
|---|---|
0x40 |
request |
0xC0 |
response |
0x00 |
notify |
On the UDP datalink each frame is wrapped in extra headers. See DUML transport. The pcap tool sidesteps that wrapping by scanning for CRC-valid frames.