I3x Interoperability Api Guide 

Overview

The Timebase Historian implements the CESMII i3X API — a standard data exchange interface developed by the Clean Energy Smart Manufacturing Innovation Institute (CESMII). If you are using a platform that supports i3X (such as the CESMII Smart Manufacturing Platform), you can connect it directly to the Historian without writing any custom integration.

The i3X API gives those platforms a standard way to:

• Browse datasets and tags (Explore endpoints)
• Read the current value of any tag (Query — last known value)
• Read historical data for any tag over a time range (Query — history)

The i3X API is separate from the Historian's primary REST API and has its own documentation page at /i3x/help.

How to use the i3X API

Finding the API

The i3X API is available at:

http://<historian>:4511/i3x/

Replace <historian> with the hostname or IP address of your Historian.

An interactive API documentation page (Swagger UI) is available at:

http://<historian>:4511/api/help/index.html

You can use the Swagger page to explore and test all i3X endpoints directly from your browser. Remeber to select the i3x definition in the swagger documents 

Tag identifiers — ElementId

The i3X standard identifies every piece of data with an ElementId. In Timebase, the ElementId for a tag is:

{dataset}:{tagname}

For example, a tag named 131-TT-001.PV in a dataset named OPCUA Demo has the ElementId:

OPCUA Demo:131-TT-001.PV

The colon (:) is the separator. Dataset names cannot contain a colon, so the separator is always unambiguous.

Endpoints

All endpoints are under the /i3x/ base path. The API is divided into two categories:

Explore — browse your data

Query — read values

Reading the current value of a tag

Send a POST request to /i3x/objects/value with the ElementId of the tag you want:

POST /i3x/objects/value
Content-Type: application/json

{
  "elementId": "OPCUA Demo:131-TT-001.PV"
}

To read multiple tags in one request, use elementIds instead:

POST /i3x/objects/value
Content-Type: application/json

{
  "elementIds": ["OPCUA Demo:131-TT-001.PV", "OPCUA Demo:131-PT-002.PV"]
}

The response wraps results in a standard i3X batch format:

{
  "results": [
    {
      "elementId": "OPCUA Demo:131-TT-001.PV",
      "success": true,
      "data": {
        "elementId": "OPCUA Demo:131-TT-001.PV",
        "isComposition": false,
        "value": {
          "value": 56.79,
          "quality": "GOOD",
          "timestamp": "2026-04-29T10:30:00.000Z"
        }
      },
      "error": null
    }
  ],
  "totalRequested": 1,
  "totalSuccess": 1,
  "totalFailed": 0
}

Reading historical data

Send a POST request to /i3x/objects/history with the ElementId and the time range you want. Both startTime and endTime are required:

POST /i3x/objects/history
Content-Type: application/json

{
  "elementId": "OPCUA Demo:131-TT-001.PV",
  "startTime": "2026-04-29T00:00:00Z",
  "endTime": "2026-04-29T01:00:00Z"
}

Timestamps must be in ISO 8601 / RFC 3339 format (e.g., 2026-04-29T14:30:00Z). The response contains an array of VQT (Value-Quality-Timestamp) records for the requested period.

Quality values

The i3X API returns quality as a string rather than a numeric code. The mapping from Timebase quality codes is:

Batch requests — single vs. multiple tags

All query and look-up endpoints support both single and batch requests. Use exactly one of:

• "elementId": "..." — for a single tag
• "elementIds": ["...", "..."] — for multiple tags

Providing both, or neither, returns a 422 Unprocessable Entity error.

In batch responses, each tag's result appears separately in the results array. If one tag is not found, its entry shows "success": false with an error message — the other tags in the same request are still returned successfully.

Authentication

As of Timebase 1.3.1, authentication is not yet enforced on the i3X API endpoints. CORS is enabled, so cross-origin browser requests work without additional configuration. Authentication enforcement will be added in a future release.

Troubleshooting