rscp_lib

An asyncio Python client library for E3/DC's RSCP (Remote Storage Control Protocol) — the TCP protocol used to communicate with E3/DC home-storage and energy-management devices (default port 5033).

The library handles the full protocol stack:

• TCP framing (0xDCE3 magic, timestamp, length)
• AES/Rijndael-256 CBC encryption with stateful IV chaining
• Authentication (user/password)
• Typed tag/value (TLV) (de)serialization, including nested containers
• A small path/filter query language for extracting values from responses

Requirements

• Python 3.9+
• py3rijndael

pip install py3rijndael

Installation

The package is not yet published to PyPI. Install directly from the repository:

pip install git+https://github.com/<your-user>/e3dc_rscp_lib.git

or clone and add the project root to your PYTHONPATH.

Quick start

import asyncio

from rscp_lib.RscpConnection import RscpConnection
from rscp_lib.RscpEncryption import RscpEncryption
from rscp_lib.RscpFrame import RscpFrame
from rscp_lib.RscpValue import RscpValue


async def main():
    cipher = RscpEncryption("YOUR_RSCP_PASSPHRASE")
    conn = RscpConnection(
        host="192.168.1.50",
        port=5033,
        ciphersuite=cipher,
        username="user@example.com",
        password="portal-password",
    )

    await conn.connect()
    if not await conn.authorize():
        raise RuntimeError("authentication failed")

    # Request the current PV power
    request = RscpValue().withTagName("TAG_EMS_REQ_POWER_PV", None)
    await conn.send(RscpFrame().packFrame(request))

    data = await conn.receive()
    frame = RscpFrame()
    frame.unpack(data)

    for value in frame.getRscpValues():
        print(value.toString())

    conn.disconnect()


asyncio.run(main())

Building requests

Simple values use withTagName:

RscpValue().withTagName("TAG_EMS_REQ_POWER_BAT", None)

Nested containers can be built declaratively via construct_rscp_value:

req = RscpValue.construct_rscp_value(
    "TAG_RSCP_REQ_AUTHENTICATION",
    [
        ["TAG_RSCP_AUTHENTICATION_USER", "user@example.com"],
        ["TAG_RSCP_AUTHENTICATION_PASSWORD", "secret"],
    ],
)

Reading responses

For navigating deeply nested container responses, use the path helper:

values = frame.getRscpValues()

# Direct child
soc = RscpValue.get_tag_by_path(values, "TAG_EMS_BAT_SOC")

# Nested path
v = RscpValue.get_tag_by_path(values, "TAG_PVI_DATA/TAG_PVI_DC_POWER")

# Filter a container by a child tag's value, then descend
string0 = RscpValue.get_tag_by_path(
    values,
    "TAG_PVI_DATA(TAG_PVI_INDEX==0)/TAG_PVI_DC_POWER",
)

Architecture

The stack is built from four composable layers:

RscpTags.py contains the full tag dictionary (tag name → tag code + declared type), used for both packing outgoing values and decoding incoming ones.

Protocol notes

A few things worth knowing when extending the library:

• Encryption IVs start as 0xff × 32 and are updated to the last ciphertext block after every operation. A new connection must call RscpEncryption.reset() (RscpConnection.connect() does this automatically).
• TAG_RSCP_AUTHENTICATION responses on failure come back as Int32 instead of the declared UChar8 — handled as a special case in RscpValue.unpack.
• Error tags use type id 0xFF; a 1-byte payload is an Error8, a 4-byte payload an Error32. Check RscpValue.isError after unpacking.
• Ciphertext whose length is not a multiple of the block size cannot be decrypted — decrypt() returns None and a warning is logged. The caller is expected to read more bytes and retry.
• Outgoing frames set nanoseconds to 0; only int(time.time()) is transmitted.

Status

This is an independent implementation of the RSCP protocol based on publicly available documentation and is not affiliated with or endorsed by E3/DC GmbH. The tag dictionary is fairly complete, but not every tag combination has been exercised against real hardware. Contributions and bug reports are welcome.

License

The code is distributed under MIT license. See LICENSE file for details.