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Use MQTT for continuous machine data ingestion from PLCs, SCADA systems, and IoT gateways. For an overview of machine data concepts, config hierarchy, and ingestion semantics, see Machine data.

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Connection

Connect to the Cula MQTT ingestion cluster over TLS (port 8883). Credentials are issued by the Cula team alongside your OAuth2 client credentials.
ParameterValue
ProtocolMQTT over TLS
Port8883
AuthenticationUsername + password (issued by Cula)

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Topic format

{payloadFormat}/{customerName}/{siteName}/{measurementName}
SegmentDescription
payloadFormatData format identifier (e.g. ixon, sparkplug)
customerNameYour organisation identifier
siteNameThe site the data originates from
measurementNameThe measurement group name

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Payload

The payload is a JSON object with a metrics array. Each metric references a machine data point config by name, using the config ID. 
{
  "metrics": [
    {
      "datatype": 9,
      "timestamp": 1761390172932,
      "name": "mdp_01kqzcjrpyf27tge9dnvsqv8t2",
      "value": 33.3
    },
    {
      "datatype": 9,
      "timestamp": 1761390172932,
      "name": "mdp_01kqzcjrpyf27tge9mg18vyhr2",
      "value": 66.7
    }
  ]
}
FieldTypeDescription
datatypeintegerData type identifier from the source system
timestampintegerUnix timestamp in milliseconds
namestringMachine data point config ID (mdp_...)
valuenumberMeasured value
The MQTT wire format uses timestamp as Unix milliseconds and name for the config ID. The HTTP endpoints use ISO-8601 timestamps and machine_data_point_config_id instead. See data shape for the canonical HTTP format.

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Example: IXON gateway

Topic: ixon/greencarbon/gc-refinery/rawgas-upgrade-1 
{
  "metrics": [
    {
      "datatype": 9,
      "timestamp": 1761390172932,
      "name": "mdp_01kqzcjrpyf27tge9dnvsqv8t2",
      "value": 33.3
    },
    {
      "datatype": 9,
      "timestamp": 1761390172932,
      "name": "mdp_01kqzcjrpyf27tge9mg18vyhr2",
      "value": 66.7
    }
  ]
}
MQTT is for continuous, high-frequency data streams. For one-off imports or backfills, use the HTTP batch ingest or import jobs endpoints instead.