Adding measurements to a REST API collector

Define what to extract from the API response and how to write it to Historian. A measurement maps value(s), timestamp(s), optional status, and tags from the JSON payload. Use JSONPath to point to the right fields, try: jsonpath.com.

MeasurementPath

The json path that leads to a value, or a list of values in the message. Default: $.Value

Examples

$.data[*].reading $.records[0].fields.freeplaces

TimestampPath

The json path that leads to a timestamp, or a list of timestamps in the message Default: $.time

Examples

$.data[*].ts $.records[0].fields.timestamp

Make sure your timestamps match the configured TimestampLayout (RFC3339 or UNIX*). If the API uses epoch millis, set TimestampLayout = "UNIXMILLIS" (either at collector or measurement level).

StatusPath (optional)

The json path that leads to a status, or a list of statuses in the message. If not set, status will default to Good

Examples

$.points[*].quality $.status

TagNamesAndTagValuePaths (optional)

Map of tag name → JSONPath to enrich points with context (site, line, sensor, batch, …).

Examples

{ "siteId": "$.meta.siteId", "sensor": "$.records[0].fields.sensor_id" }

A single-value tag applies to all points in the batch. If you provide tag lists, their length should match the number of values.

TimestampLayout (override)

Optional per-measurement override of the parsing layout. Use when a specific measurement’s timestamps differ from the collector default.

Examples

"UNIX" "2006-01-02 15:04:05"

URL / QueryParameters / Body / Method / Headers (overrides)

Optional per-measurement overrides. Unset fields fall back to the collector settings.

Use cases

Point a subset of measurements to a different endpoint path.

Add a small extra filter (e.g., tag=temperature) for this measurement only.

Switch a measurement from GET to POST when it needs a complex body.

Keep overrides minimal: each unique combination (URL/Method/Headers/QueryParameters/Body) can create an additional API call path.

Interval / IntervalOffset (overrides)

Per-measurement polling cadence and alignment. Use to slow down non-critical reads or to stagger calls across seconds.

Examples

Interval: 30 IntervalOffset: 5

CollectionType

Defines when values are written.

polled (default): fetch each interval and write every response.

monitored: fetch each interval but write only when the value changes.

Guidance

Use polled for numeric time series that change frequently.

Use monitored for states/booleans/strings (e.g., valve open/closed) to reduce noise.

Expected outcome

Measurement appears in the list.

Status changes to Good within ~10 seconds.

Data preview shows live values.