Adding measurements to an MQTT (JSON) collector

Once the collector is connected, you can add one or more measurements. A measurement defines how data from a subscribed topic is mapped into Historian.

To create a new measurement manually, go to the Measurements page in Historian and click + Create Measurement.

You can find JSONPath documentation online, and jsonpath.com is a useful tool to quickly test expressions against sample messages before configuring them in Historian.

Example configuration: Assume your broker publishes the following JSON message on topic factory/machine1/metrics:

{
 "temperature": 23.5,
 "pressure": 1012,
 "status": "Good",
 "machineId": "Mixer-01",
 "ts": "2025-09-18T09:45:00Z"
 }

You can configure a measurement with:

MeasurementPath: $.temperature

TimestampPath: $.ts

StatusPath: $.status

TagNamesAndTagValuePaths: {"machine": "$.machineId"}

If the timestamp is in UNIX format, set TimestampLayout to UNIX, UNIXMILLIS, UNIXMICROS, or UNIXNANOS. Otherwise RFC3339 is assumed.

Expected outcome:

The measurement status changes to Good within a few seconds.

Live values appear in the data preview panel.

The measurement shows up in the configured measurements list.