Using MQTT Modules to map ISA 95 Enterprise Structure in a UNS Architecure

How can we use Cirrus Link's Sparkplug MQTT Transmission and MQTT Engine modules along with the common ISA-95 equipment model of Enterprise > Site > Area > Line > Equipment to map the model data into a Unified NameSpace.

Sparkplug Basics

Sparkplug defines a standard format for MQTT message topic paths of:

spBv1.0/group_id/Message Type/edge_node_id/device_id

Sparkplug defines a standard format for MQTT message payloads of:

{         
  "timestamp": <timestamp>,         
  "metrics": [{                 
    "name": <metric_name>,                 
    "alias": <alias>,                 
    "timestamp": <timestamp>,                 
    "dataType": <datatype>,                 
    "value": <value>
  }],
  "seq": <sequence_number>
}

where the ‘name’ of a metric can be hierarchical to build out proper folder structures for applications consuming the metric values.

For example, a simple Sparkplug™ B payload with a two metrics can be represented in JSON as follows:

{         
  "timestamp": 1486144502122,         
  "metrics": [{                 
    "name": "Metric1",                 
    "alias": 1,                 
    "timestamp": 1479123452194,                 
    "dataType": "String",                 
    "value": "Test"         
  },
  {                 
    "name": "Metric Level 1/Metric Level 2/Metric2",                 
    "alias": 2,                 
    "timestamp": 1479123452056,                 
    "dataType": "String",                 
    "value": "Test"         
  }],         
  "seq": 2
}

Using the hierarchal functionality of the metric name, in conjunction with the group_id, edge_node_id and device_id already defined in the Topic Namespace, allows consuming Sparkplug applications to organize metrics in the same hierarchical fashion.

Let's take a look at a couple of examples using MQTT Transmission and MQTT Engine.

Review the MQTT Transmission Transmitters and Tag Trees to gain an understanding of how MQTT Transmission Transmitter configurations interact with Ignition tag trees to publish Sparkplug messages and the immense flexibility that can be realized.

We have configured an MQTT Transmission Transmitter to use the Ignition tag tree at the edge to construct the group_id, edge_id and device_id starting at the folder level Site_1. With this configuration, the topic and payload for a change to Tag 1 will be:

Topic: spBv1.0/Site 1/DDATA/Area 1/Line 1
- Payload: {"timestamp":1643823757750,"metrics":[{"name":"Equipment 1/Tag 1","timestamp":1643823756467,"dataType":"Boolean","value":True}],"seq":23}

At MQTT Engine, this hierarchal metric name is parsed and the edge folder structure recreated

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Cirrus Link Resources

Inductive Resources