# Calibrations

> [!note] Esta página ainda não foi traduzida e é apresentada em inglês.


Calibration brings a connected device's measurement chain back into agreement with a known reference (white, black, or height target). For instruments such as Aesthetix, a valid calibration is a precondition for trustworthy measurements — running a measurement on an uncalibrated device returns numbers, but they are not metrologically meaningful. The hub tracks the last calibration time per device and exposes a `status` endpoint so clients can prompt for re-calibration before it goes stale.

### Endpoints Overview

| Method | Endpoint | Description |
| --- | --- | --- |
| GET | `/v1/devices/{deviceId}/calibrations` | List calibrations available on the connected device |
| POST | `/v1/devices/{deviceId}/calibrations` | Execute a calibration |
| GET | `/v1/devices/{deviceId}/calibrations/status` | Get current calibration status per calibration type |

### Listing Available Calibrations

```http
GET /v1/devices/{deviceId}/calibrations
```

```bash
curl http://localhost:42042/v1/devices/12f1d7dd07ac42a088c8f961b39d68ff/calibrations
```

Returns the device's calibration definitions, including the parameters each one accepts. Example shape:

```json
[
  {
    "identifier": "white",
    "title": "White Calibration",
    "description": "Performs white reference calibration using the white calibration standard.",
    "category": "calibration",
    "parameters": [
      { "key": "reflectance",    "type": "Double", "description": "Percent, 0.42 ≙ 42 %" },
      { "key": "visualContrast", "type": "Double", "description": "Percent, 0.42 ≙ 42 %" }
    ]
  }
]
```

The set of calibrations is device-class–specific. For example, an Aesthetix supports `white`, `black` and `height`, an Aesthetix Inline only `black`. See [Aesthetix-specific calibration details](rhopoint-elements-hub-instruments-aesthetix-calibration.md).

### Executing a Calibration

```http
POST /v1/devices/{deviceId}/calibrations
Content-Type: application/json

{
  "calibrationKey": "white",
  "parameters": [
    { "key": "reflectance",    "value": 0.95 },
    { "key": "visualContrast", "value": 0.92 }
  ]
}
```

```bash
curl -X POST http://localhost:42042/v1/devices/12f1d7dd07ac42a088c8f961b39d68ff/calibrations \
  -H "Content-Type: application/json" \
  -d '{
    "calibrationKey": "white",
    "parameters": [
      { "key": "reflectance",    "value": 0.95 },
      { "key": "visualContrast", "value": 0.92 }
    ]
  }'
```

#### Request Body

| Field | Type | Required | Description |
| --- | --- | --- | --- |
| `calibrationKey` | string | Yes | Identifier from `GET /v1/devices/{deviceId}/calibrations` (e.g. `white`, `black`, `height`). |
| `parameters` | array | No | Calibration parameters as `{ "key": "...", "value": ... }` entries. Keys and value types are device-class–specific (see `GET` response). |

#### Response

```json
{
  "calibrationKey": "white",
  "success": true
}
```

The call is synchronous and only returns once the calibration has completed on the device. Calibration can take several seconds; clients should set a generous HTTP timeout (≥30 s).

> [!warning]
> The physical calibration target must be in place **before** the request is sent. Calibrating against the wrong target will produce a successful response but invalid downstream measurements. See the device-specific calibration page for which target to use with which `calibrationKey`.

### Getting the Calibration Status

```http
GET /v1/devices/{deviceId}/calibrations/status
```

Returns the current state of every calibration type the device supports:

```json
{
  "deviceId": "12f1d7dd07ac42a088c8f961b39d68ff",
  "deviceSerialNumber": "AXI8000027",
  "calibrations": [
    {
      "calibrationKey": "white",
      "lastCalibrationTime": "2025-11-10T07:32:14.000Z",
      "status": "CalibrationValid",
      "recommendedInterval": "2.00:00:00",
      "overdueInterval": "7.00:00:00"
    },
    {
      "calibrationKey": "black",
      "lastCalibrationTime": null,
      "status": "NotCalibrated",
      "recommendedInterval": "2.00:00:00",
      "overdueInterval": "7.00:00:00"
    }
  ]
}
```

#### Status Values

| Status | Meaning | Recommended action |
| --- | --- | --- |
| `NotCalibrated` | No calibration of this type has ever been performed for this device's serial number. | Calibrate before measuring. |
| `CalibrationValid` | Last calibration is younger than `recommendedInterval`. | Continue measuring. |
| `CalibrationRecommended` | Last calibration is older than `recommendedInterval` but younger than `overdueInterval`. | Calibrate at the next convenient point. |
| `CalibrationOverdue` | Last calibration is older than `overdueInterval`. | Calibrate before further measurements. |

The intervals follow .NET `TimeSpan` formatting (`d.hh:mm:ss`). Typical defaults are 2 days (recommended) and 7 days (overdue), but the device definition is authoritative — read the values from the response rather than hard-coding them.

### Persistence

Calibration data is stored per **serial number + device class**, not per session identifier. Disconnecting and re-connecting a device — or restarting the hub — does not invalidate previously persisted calibrations. The storage location is the `dataDirectory` passed to [`POST /v1/lifecycle/initialize`](rhopoint-elements-hub-endpoints-functionality-lifecycle.md).

### Best Practices

- After connecting a device, call `GET /v1/devices/{deviceId}/calibrations/status` and surface any `NotCalibrated`, `CalibrationRecommended` or `CalibrationOverdue` entries to the operator before allowing measurements to start.
- Calibrate in the order recommended by the device manufacturer (typically Black → White → Height for Aesthetix). Some calibrations depend on earlier ones being valid.
- Read `parameters` from `GET /v1/devices/{deviceId}/calibrations` and only send the values listed there — sending unknown keys is silently ignored, which makes typos hard to spot.
- Time the calibration prompts using the `status` endpoint, not your own scheduler — the intervals can change between firmware updates.

### Error Cases

| Condition | HTTP | Error Code |
| --- | --- | --- |
| Connected device not found | 404 | `E5` |
| Unknown `calibrationKey` for this device | 404 | `E28` |
| Calibration timed out (hardware likely disconnected) | 502 | `E29` |

See [Error Handling](rhopoint-elements-hub-error-handling.md) for the response format.