cta2045-proxy 0.2.0

Proxy a CTA-2045 (EcoPort) Smart Grid Device onto the Electrification Bus (eBus / Homie 5), via a pluggable UCM backend

cta2045-proxy

Proxy a CTA-2045 (EcoPort) Smart Grid Device onto the Electrification Bus (eBus / Homie 5), through a pluggable UCM backend.

Status: pre-alpha. The SkyCentrics UCM backend is functional and validated end to end against a live SkyCentrics Ethernet UCM: telemetry decode, the full Homie device tree, and bidirectional demand-response control. The public API may still change before 1.0. Published to PyPI as cta2045-proxy (pip install cta2045-proxy). It has not been certified under any conformance program and carries no warranty of interoperability.

What it does

A CTA-2045 appliance (an SGD, e.g. a water heater) speaks demand-response through a UCM. This service bridges that appliance onto eBus so any eBus/Homie 5 controller can read its telemetry and command demand-response events, published per the eBus proxy and water-heater data models:

ebus/5/{MAC}/       energy.ebus.device.bridge        (the UCM)
ebus/5/{MAC}-wh01/  energy.ebus.device.water-heater  (the proxied appliance)

The UCM is a pluggable backend, not a fixed assumption. CTA-2045 standardizes only the SGD-to-UCM link; how a UCM reaches the network is vendor-specific, so each UCM is a separate backend behind the vendor-neutral cta2045.ucm.Ucm interface. A SkyCentrics Ethernet UCM (over MQTT) ships today; the same CTA-2045 decode and eBus device model serve any future UCM without change:

• other vendors' CTA-2045 UCMs (add a backend for that dongle's transport),
• a native own-UCM that drives the CTA-2045 RS485 link layer directly, with no vendor dongle at all (reserved; see below).

Adding support for a new UCM means writing one backend; the appliance-side mapping and Homie publishing are shared across all of them.

Architecture

Three layers, cleanly separated:

• cta2045 (upstream lib) - the CTA-2045 protocol codec and the abstract, vendor-neutral cta2045.ucm.Ucm interface. Pure, no I/O.
• cta2045_proxy.ucm - concrete UCM backends binding Ucm to a real transport. Variants differ ONLY here:
  • skycentrics - a SkyCentrics Ethernet UCM (US08C) reachable over MQTT. Ships today.
  • native - an own-UCM driving the CTA-2045 RS485 link layer directly, no vendor dongle. Reserved; blocked on cta2045.link.
• cta2045_proxy.mapping + .emitter - the CTA-2045 -> eBus water-heater data-model translation and the Homie adapter, shared across all backends. Built on ebus-sdk's declarative proxy layer (PropertySpec + build_from_declarations); see the SDK's doc/building-a-proxy.md.

Install

pip install cta2045-proxy

Requires Python 3.10+. For local development, clone the repo and install editable with the dev extras instead: pip install -e ".[dev]".

Run

cp config/config.example.toml config/config.toml   # then edit
export EBUS_MQTT_PASS=...                           # secrets via env, never the file
cta2045-proxy --config config/config.toml

See config/config.example.toml for the [ucm] backend selector and the [ebus] output broker. A downstream deployment customizes only the config; the code is deployment-neutral.

The command runs in the foreground and waits until interrupted (SIGINT/SIGTERM), tearing down its eBus tree on exit.

usage: cta2045-proxy [-h] --config CONFIG [--log-level LOG_LEVEL] [--version]

  --config CONFIG        path to the config TOML (required)
  --log-level LOG_LEVEL  logging level (default: INFO, or $LOG_LEVEL)
  --version              print the version and exit
  -h, --help             show this help and exit

Exit codes: 0 on clean shutdown, 2 on a usage error (missing or unknown flag), 1 on a startup or runtime error (bad config path, malformed TOML, or a failure in the run loop).

Bring up a SkyCentrics UCM

tools/ has helper scripts to discover a SkyCentrics Ethernet UCM on your LAN, point it at a broker, and confirm it is publishing (ucm-discover, ucm-configure, ucm-watch), plus a how-to for standing up a local test broker (via the sibling broker-quickstart or a bare Mosquitto). See tools/README.md.

Example: the published Homie tree

A live capture of what the proxy publishes for one SkyCentrics UCM (84FEDC538C72) feeding one water heater. The bridge is the UCM; its child is the proxied appliance:

ebus/5/
├── 84FEDC538C72/                     # bridge device (the UCM)
│   ├── $state = ready
│   ├── info/
│   │   ├── vendor-name = SkyCentrics
│   │   └── firmware-version = v2.2 (26 June 2026, 9:0:0)
│   └── connection/
│       ├── feeds-device-id = 84FEDC538C72-wh01
│       ├── feeds-device-type = energy.ebus.device.water-heater
│       ├── feeds-device-status = OK
│       └── last-seen = 2026-07-05T20:24:49Z
└── 84FEDC538C72-wh01/                # proxied device (the water heater / SGD)
    ├── $state = ready
    ├── info/
    │   └── fuel-type = (unset until the SGD reports it)
    ├── meter/
    │   ├── active-power = 0.0 W
    │   └── imported-energy = 733.0 Wh
    ├── soc/
    │   ├── soe = 0.0 Wh
    │   ├── total-energy-storage = 4500.0 Wh
    │   └── loadup-headroom = (unset)
    ├── flex/
    │   ├── response = NONE
    │   ├── opt-out = NONE
    │   ├── request = (settable — publish a flex command to .../flex/request/set)
    │   └── active-request = {"mode": "NORMAL"}
    └── status/
        └── fault-state = OK

flex is the vendor-neutral demand-response control-and-feedback capability (energy.ebus.capability.flex). The settable request property advertises the device's accepted control surface in its Homie 5 $format JSONSchema, and the proxy validates each inbound /set against it (strictly: unknown fields are rejected, not ignored) before translating. For a CTA-2045 SGD that schema accepts mode (SHED / LOAD_UP / NORMAL), intensity (PEAK / EMERGENCY / ADVANCED), duration (seconds), an advisory cause, and, for load-up, a target-percentage (heat until stored-energy soc reaches that %, encoded as CTA-2045 Advanced Load Up). It omits level (the SGD sheds/loads-up without a percentage) and temporary-setpoint (CTA-2045 quantifies Advanced Load Up in watt-hours, not degrees).

Send a demand-response command by publishing to the settable request property, e.g. a 10-minute shed:

mosquitto_pub -t 'ebus/5/84FEDC538C72-wh01/flex/request/set' -m '{"mode":"SHED","duration":600}'

The proxy validates it against the request $format, encodes it to CTA-2045, and forwards it to the UCM (devices/84FEDC538C72/ctl/shed); the SGD's resulting state flows back to flex/response (e.g. CURTAILED).

Development

ruff check . && ruff format --check .
pytest tests/ -v

Optionally install the pre-commit hooks (ruff format + lint on every commit, mirroring CI):

pip install pre-commit && pre-commit install

CI (.github/workflows/) runs the same ruff checks and pytest on 3.10 / 3.12 for every push and PR.

Releasing

The version has a single source of truth: __version__ in src/cta2045_proxy/__init__.py. Both build paths read it (the modern pyproject.toml via dynamic = ["version"], and the legacy setup.py shim for Yocto/kirkstone), so there is exactly one line to bump.

To cut a release:

1. Bump __version__ in src/cta2045_proxy/__init__.py (the only place).
2. Commit it (git commit -am "release X.Y.Z").
3. Tag it to match, prefixed with v: git tag vX.Y.Z.
4. Push the tag: git push --tags (a plain git push alone does not trigger a release).

Pushing a v* tag runs publish.yml: it reruns the tests, verifies the tag equals v$__version__ (a mismatch fails the run before anything is published), builds the sdist + wheel, and publishes to PyPI via Trusted Publishing (OIDC, no stored token). The tag and the packaged version can therefore never disagree in a published artifact.

References

• CTA-2045 protocol library (cta2045)
• ebus-sdk building-a-proxy guide
• eBus specification