# Reference — Contracts

![code-ref](https://img.shields.io/badge/code--ref-b884c0f-blue)

> [!NOTE]
> Full topic contract, configuration schema, and child-registration handshake for `measurement`. Source of truth: `src/commands/index.js`, `src/commands/handlers.js`, `src/specificClass.js` `configure()`, and the schema at `generalFunctions/src/configs/measurement.json`.
>
> Pending full node review (2026-05). Hand-written best-effort placeholder where indicated. For an intuitive overview, return to [Home](Home).

---

## Topic contract

The registry lives in `src/commands/index.js`. Each descriptor maps a canonical `msg.topic` to a handler; aliases emit a one-time deprecation warning the first time they fire.

<!-- BEGIN AUTOGEN: topic-contract -->

| Canonical topic | Aliases | Payload | Unit | Effect |
|---|---|---|---|---|
| `set.simulator` | `simulator` | any | — | Toggle the built-in simulator on / off. |
| `set.outlier-detection` | `outlierDetection` | any | — | Toggle / configure outlier detection on the measurement pipeline. |
| `cmd.calibrate` | `calibrate` | any | — | Trigger a one-shot calibration of the measurement. |
| `data.measurement` | `measurement` | any | — | Push a raw measurement (analog: number; digital: per-channel object). |

<!-- END AUTOGEN: topic-contract -->

### Payload-shape rules

| Mode | Accepted | Rejected (logs warn) |
|:---|:---|:---|
| `analog` | `number`; numeric string (trimmed, non-empty, parses with `Number`) | object payload (hint: "Switch Input Mode to 'digital' &hellip;"); non-numeric string |
| `digital` | object `{ key1: number, key2: number, &hellip; }` &mdash; keys must match `config.channels[*].key` | number (hint: "Switch Input Mode to 'analog' &hellip;"); array; any non-object |

Unknown channel keys in a digital payload are collected and reported at `debug` level via `digital payload contained unmapped keys: <list>`.

### Source / mode allow-lists

> [!NOTE]
> TODO: `measurement` does not appear to implement a `flowController`-style action/source allow-list (consult `src/specificClass.js`); it relies on the topic registry's typeof checks. If a future hardening pass adds mode-source gating, fold the table in here.

---

## Data model &mdash; `getOutput()` shape

Source: `src/specificClass.js` `getOutput()` / `getDigitalOutput()` and `src/channel.js` `getOutput()`. Delta-compressed by `outputUtils.formatMsg`: consumers see only the keys that changed.

<!-- BEGIN AUTOGEN: data-model — populate via wiki-gen tool (TODO) -->

### Analog mode (`Measurement.getOutput()`)

| Key | Type | Unit | Notes |
|:---|:---|:---|:---|
| `mAbs` | number | scaling units (`asset.unit` / `general.unit`) | Latest output value after offset + scaling + smoothing. Rounded to 2 dp. |
| `mPercent` | number | % | Output mapped to `interpolation.percentMin..percentMax`. Rounded to 2 dp. |
| `totalMinValue` | number | scaling units | Rolling minimum of the **post-offset, pre-smoothing** values. Reported as `0` until the first sample. |
| `totalMaxValue` | number | scaling units | Rolling maximum of the same. Reported as `0` until the first sample. |
| `totalMinSmooth` | number | scaling units | Rolling minimum of the smoothed output. Starts at `0`. |
| `totalMaxSmooth` | number | scaling units | Rolling maximum of the smoothed output. Starts at `0`. |

### Digital mode (`Measurement.getDigitalOutput()`)

```jsonc
{
  "channels": {
    "<channel.key>": {
      "key":            "<channel.key>",
      "type":           "<channel.type>",
      "position":       "<channel.position>",
      "unit":           "<channel.unit>",
      "mAbs":           <number>,
      "mPercent":       <number>,
      "totalMinValue":  <number>,
      "totalMaxValue":  <number>,
      "totalMinSmooth": <number>,
      "totalMaxSmooth": <number>
    }
    // ... one entry per channel that has produced output
  }
}
```

<!-- END AUTOGEN: data-model -->

### Status badge

`Measurement.getStatusBadge()`:

| Mode | Badge text | Fill / shape |
|:---|:---|:---|
| `analog` | `<mAbs> <unit>` (e.g. `0.42 bar`) | green / dot |
| `digital` | `digital · <N> channel(s)` | blue / ring |

The legacy `source.emitter` fires `'mAbs'` (analog only) and is kept for the editor status badge during the refactor window &mdash; see [Limitations](Reference-Limitations#legacy-source-emitter).

---

## Events emitted on `source.measurements.emitter`

The shared `MeasurementContainer` fires `<type>.measured.<position>` whenever a `Channel`'s rounded output changes. The type / position come from:

- **analog**: `config.asset.type` and `config.functionality.positionVsParent`.
- **digital**: per-channel `config.channels[i].type` and `config.channels[i].position` (falls back to the node-level `positionVsParent` when missing).

Position labels are normalised to **lowercase** in the event name (`upstream`, `downstream`, `atequipment`). Examples:

- `pressure.measured.upstream`
- `flow.measured.atequipment`
- `level.measured.downstream`
- `temperature.measured.atequipment`

Parents subscribe through the generic `child.measurements.emitter.on(eventName, &hellip;)` handshake established by `childRegistrationUtils` (in `generalFunctions`).

In digital mode one input message can fan out into several events &mdash; one per channel that accepted a value on that tick.

---

## Configuration schema &mdash; editor form to config keys

Source of truth: `generalFunctions/src/configs/measurement.json` plus `nodeClass.buildDomainConfig`. Defaults below come from the schema.

### General (`config.general`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Name | `general.name` | `Sensor` | Human-readable label. |
| (auto-assigned) | `general.id` | `null` | Node-RED node id. |
| Default unit | `general.unit` | `unitless` | Falls back to the asset unit. |
| Enable logging | `general.logging.enabled` | `true` | Master switch. |
| Log level | `general.logging.logLevel` | `info` | `debug` / `info` / `warn` / `error`. |

### Functionality (`config.functionality`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Software type | `functionality.softwareType` | `measurement` | Constant. |
| Role | `functionality.role` | `Sensor` | Constant. |
| Position vs parent | `functionality.positionVsParent` | `atEquipment` | One of `atEquipment` / `upstream` / `downstream`. Used in the `child.register` payload and as the suffix of the measurement event name. |
| Distance offset | `functionality.distance` | `null` | Optional spatial offset; sent with `child.register`. |

### Asset (`config.asset`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Asset UUID | `asset.uuid` | `null` | Globally-unique identifier. |
| Tag code / number | `asset.tagCode` / `asset.tagNumber` | `null` | Asset-registry identifiers. |
| Geolocation | `asset.geoLocation` | `{x:0, y:0, z:0}` | |
| Supplier | `asset.supplier` | `Unknown` | Free text. |
| Category | `asset.category` | `sensor` | `sensor` / `measurement`. |
| Asset type | `asset.type` | `pressure` | **Required.** Matches the type axis on `MeasurementContainer` and the parent's filter (e.g. `flow`, `power`, `temperature`). |
| Model | `asset.model` | `Unknown` | Free text. |
| Asset unit | `asset.unit` | `unitless` | Output unit label for the measurement event payload. |
| Accuracy | `asset.accuracy` | `null` | Optional sensor accuracy. |
| Repeatability | `asset.repeatability` | `null` | Optional repeatability metric. |

> [!IMPORTANT]
> `asset.type` must match the **exact** string the parent listens for. The parent's filter is typically the bare type (`flow`, `pressure`, `power`, &hellip;) &mdash; a measurement configured as `flow-electromagnetic` will not register with a `flow`-only filter on its parent (see [Limitations](Reference-Limitations#asset-type-must-match-the-parents-filter-exactly)).

### Scaling (`config.scaling`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Scaling enabled | `scaling.enabled` | `false` | When false, the input is passed through with only the offset applied. |
| Input min/max | `scaling.inputMin` / `scaling.inputMax` | `0` / `1` | Source range; clamps the input before mapping. |
| Output min/max | `scaling.absMin` / `scaling.absMax` | `50` / `100` | Target range. |
| Offset | `scaling.offset` | `0` | Added before scaling; mutated by `cmd.calibrate`. |

### Smoothing (`config.smoothing`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Window size | `smoothing.smoothWindow` | `10` | `>= 1`. Rolling buffer length. |
| Method | `smoothing.smoothMethod` | `mean` | One of `none` / `mean` / `min` / `max` / `sd` / `median` / `weightedMovingAverage` / `lowPass` / `highPass` / `bandPass` / `kalman` / `savitzkyGolay`. |

### Outlier detection (`config.outlierDetection`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Enabled | `outlierDetection.enabled` | `false` | Toggle with `set.outlier-detection`. |
| Method | `outlierDetection.method` | `zScore` | One of `zScore` / `iqr` / `modifiedZScore`. |
| Threshold | `outlierDetection.threshold` | `3` | Method-specific (e.g. z &gt; 3, mz &gt; 3.5). |

### Simulation (`config.simulation`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Enabled | `simulation.enabled` | `false` | When true, `tick()` (1000 ms) drives `inputValue` via `Simulator.step()`. |
| Safe calibration time | `simulation.safeCalibrationTime` | `100` | ms before calibration is finalised in sim mode. |

### Interpolation (`config.interpolation`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Percent min | `interpolation.percentMin` | `0` | Lower bound of the `mPercent` output. |
| Percent max | `interpolation.percentMax` | `100` | Upper bound. |

### Calibration (`config.calibration`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Stability threshold | `calibration.stabilityThreshold` | `0.01` | Absolute stdDev ceiling (in scaling-units) below which the buffer is considered stable. Fits the default `[50,100]` range; tighten / relax for your sensor. |

### Mode (`config.mode`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Input mode | `mode.current` | `analog` | `analog` (one channel, scalar payload) or `digital` (N channels, object payload). |

### Channels (`config.channels[]` &mdash; digital only)

In digital mode, each entry in `config.channels` defines its own pipeline:

| Field | Required | Falls back to |
|:---|:---:|:---|
| `key` | yes | &mdash; (skipped if missing) |
| `type` | yes | &mdash; (skipped if missing) |
| `position` | no | `config.functionality.positionVsParent` &rarr; `atEquipment` |
| `unit` | no | `config.asset.unit` &rarr; `unitless` |
| `distance` | no | `config.functionality.distance` &rarr; `null` |
| `scaling` | no | `{enabled:false, inputMin:0, inputMax:1, absMin:0, absMax:1, offset:0}` |
| `smoothing` | no | `config.smoothing` |
| `outlierDetection` | no | `config.outlierDetection` |
| `interpolation` | no | `config.interpolation` |

Invalid entries (missing `key` or `type`) are logged and skipped. An empty `config.channels[]` in digital mode logs `digital mode enabled but config.channels is empty; no channels will be emitted.`

### Asset registration (`config.assetRegistration`)

Used by the `/measurement/asset-reg` admin endpoint to register / sync the asset with the upstream asset registry. Not part of the runtime data path.

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Profile / location / process ids | `assetRegistration.{profileId, locationId, processId}` | `1` | Free integer ids in the asset registry. |
| Status | `assetRegistration.status` | `actief` | Lifecycle status. |
| Child assets | `assetRegistration.childAssets` | `[]` | List of child asset ids. |

### Output (`config.output`)

| Form field | Config key | Default | Notes |
|:---|:---|:---|:---|
| Process output | `output.process` | `process` | `process` / `json` / `csv`. Port-0 formatter. |
| Database output | `output.dbase` | `influxdb` | `influxdb` / `json` / `csv`. Port-1 formatter. |

### Unit policy

> [!NOTE]
> TODO: `measurement` does not currently declare a `unitPolicy` block on its `BaseDomain` configuration (unlike `rotatingMachine`). The per-channel `unit` is carried verbatim into the `MeasurementContainer` write at `_writeOutput`. If a future hardening pass adds a unit-policy enforcement, add the canonical / output / required-unit table here. See `CONTRACT.md` for the current invariants.

---

## Child registration

Source: `src/specificClass.js` `configure` (registers itself via the `BaseDomain` plumbing) and the standard `childRegistrationUtils` handshake in `generalFunctions`.

`measurement` does **not accept children**. It only **registers itself** as a child on its upstream parent.

| Layer | Direction | Topic / event | Payload |
|:---|:---|:---|:---|
| Startup (Port 2) | child &rarr; parent | `registerChild` | `{topic: 'registerChild', payload: <node.id>, positionVsParent, distance}` |
| Runtime | child &rarr; parent | `<asset.type>.measured.<positionVsParent>` on `child.measurements.emitter` | `{value, timestamp, unit, distance?}` (per `MeasurementContainer.value()`) |

| What | softwareType payload | Side-effect on parent |
|:---|:---|:---|
| Registration | `measurement` | Parent attaches a listener for `<asset.type>.measured.<positionVsParent>` on the child's `measurements.emitter`. |
| Subsequent updates | event on `child.measurements.emitter` | Parent mirrors the value into its own `MeasurementContainer` slot. |

Position labels are normalised to **lowercase** in the event name (`upstream`, `downstream`, `atequipment`); the `positionVsParent` field in the register payload is sent as configured (preserves case).

---

## Related pages

| Page | Why |
|:---|:---|
| [Home](Home) | Intuitive overview |
| [Reference &mdash; Architecture](Reference-Architecture) | Code map + per-`Channel` pipeline + lifecycle |
| [Reference &mdash; Examples](Reference-Examples) | Shipped flows + debug recipes |
| [Reference &mdash; Limitations](Reference-Limitations) | Known issues and open questions |
| [EVOLV &mdash; Topic Conventions](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Topic-Conventions) | Platform-wide topic rules |
| [EVOLV &mdash; Telemetry](https://gitea.wbd-rd.nl/RnD/EVOLV/wiki/Telemetry) | Port 0 / 1 / 2 InfluxDB layout |