Frame Format

Every RSCP message is wrapped in a frame with a fixed 18-byte header, followed by data items and an optional CRC32 checksum.

Frame Header (18 bytes)

Offset	Size	Field	Description
0	2	Magic	0xE3DC (little-endian)
2	2	Control	Version + flags (see below)
4	8	Seconds	Unix timestamp, int64 LE
12	4	Nanoseconds	Sub-second precision, int32 LE
16	2	Data Length	Length of all data items, uint16 LE

Control Field (2 bytes)

Bits [3:0]  — Protocol version (always 0x01)
Bit  [4]    — CRC enabled (1 = CRC32 appended after data)
Bits [15:5] — Reserved (0)

When the CRC bit is set, a 4-byte IEEE CRC32 is appended after all data items.

Data Item Format (7-byte header + value)

Each data item within a frame uses Tag-Length-Value encoding:

Offset	Size	Field	Description
0	4	Tag	Tag identifier, uint32 LE
4	1	DataType	Type of the value (see Data Types)
5	2	Length	Length of the value in bytes, uint16 LE
7	N	Value	The actual data (type-dependent)

Data items with DataType = Container (0x0E) contain nested data items in their value field.

Example: Requesting PV Power

A frame requesting EMS_REQ_POWER_PV (tag 0x01000001):

E3 DC       — Magic
11 00       — Control: version 1, CRC enabled
XX XX XX XX XX XX XX XX  — Timestamp seconds
XX XX XX XX              — Timestamp nanoseconds
07 00       — Data length: 7 bytes (one empty tag)
01 00 00 01 — Tag: EMS_REQ_POWER_PV
00          — DataType: None
00 00       — Length: 0
XX XX XX XX — CRC32

The response would contain EMS_POWER_PV (tag 0x01800001) with a 4-byte Int32 value representing watts.