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The MQTT Modules publish data in a JSON format with each message comprising a Topic and Payload.

The Topic contains the following key/value pairs:

• namespace
  • Set as "spBv1.0"
• edgeNodeDescriptor
  • The combination of the Group ID and Edge Node ID which provides a unique identifier for the Edge Node
• groupId
  • The Group ID
• edgeNodeId
  • The Edge Node ID
• deviceId
  • The Device ID
• type
  • Message type including:
    • NBIRTH
    • DBIRTH
    • NDATA
    • DDATA
    • NDEATH
    • DDEATH

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The Payload contains the following key/value pairs:

• timestamp
  • The time stamp that the payload was created
• metrics
  • An array containing data specific to the message type being published
  • Each object in the array will include the following name/value pairs:

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  The Edge Node BIRTH message will contain a Topic and Payload:

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  • Namespace
  • Edge Node Descriptor
  • Group ID
  • Edge Node ID
  • Message Type

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  • • • name
      • timestamp
      • dataType
      • value
    • Optional name/value pairs include:
      • metaData
        • Meta Data property values, including Tooltip and Documentation, are included if they have been changed from the Ignition default. See the Ignition Tag Properties reference for all available properties.
      • properties
        • The Quality property. See the Ignition Tag Quality Code Reference for the Data Quality value reference.
          • If the Quality property is not included, the quality of the tag data is considered Good.
        • Additional property values such as engHigh, engLow etc are included if they have been changed from the Ignition default or if they are custom properties. See the Ignition Tag Properties reference for all available properties.
  • seq
    • The message sequence number used to ensure that messages are processed in the correct order

  
  

  Note
  metaData and property values, other that Quality, are only included in the NBIRTH or DBIRTH messages and only if they have changed from the Ignition default.

  Sample JSON messages

  Using a simple tag tree structure shown below, we can show how these JSON formatted messages will be generated:

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  NBIRTH NBIRTH

  NBIRTH

  The metrics array for the Edge Node BIRTH message will contain:

  • A Birth/Death sequence number to track the Sparkplug session of the Edge client
  • Any Edge Node tags defined in the Edge Node folder
  • Seq - the message sequence number

  
  

  Code Block
  title Edge Node Birth BIRTH message
  {   "topic": {     "namespace": "spBv1.0", "edgeNodeDescriptor": "G1/E1",     "groupId": "G1",     "edgeNodeId": "E1", "type": "NBIRTH"   },   "payload": {     "timestamp": 1638223073190,     "metrics": [       {         "name": "bdSeq",         "timestamp": 1638223073187,         "dataType": "Int64",         "value": 5       }, { "name": "Tag 4", "timestamp": 1638223073156, "dataType": "Int32", "metaData": {}, "properties": { "Quality": { "type": "Int32", "value": 192 } }, "value": 100 }, { "name": "Tag 5", "timestamp": 1638223073001, "dataType": "Boolean", "metaData": {}     , "properties": { "Quality": { "type": "Int32", "value": 192 } }, "value": false }     ],     "seq": 0   } }

  
  

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  DBIRTH DBIRTH

  DBIRTH

  The metrics array for the Device BIRTH message will contain the following:

  • The Sparkplug elements: Namespace, Group ID, Edge Node ID, Device ID.  They will be grouped under "topic" along with Message Type
  • A "timestamp" for when the payload was constructed
  • Any Device tags defined in the Device folder
  • A message sequence number

  
  

  Code Block
  title Device BIRTH message
  { "topic": {        "namespace": "spBv1.0",        "edgeNodeDescriptor": "G1/E1",        "groupId": "G1",        "edgeNodeId": "E1",        "deviceId": "D1",        "type": "DBIRTH"    },    "payload": {      "timestamp": 1638223073192,      "metrics": [          {              "name": "T1Tag 1",              "timestamp": 1638223073192,             "dataType": "Int32",             , "dataType": "Int32", "metaData": {}, "properties": { "Quality": { "type": "Int32", "value": 192 } }, "value": 1 }, { "name": "Tag 2", "timestamp": 1638223073011, "dataType": "Boolean", "metaData": {}, "properties": { "Quality": { "type": "Int32", "value": 192 } }, "value": false }, { "name": "Tag 3", "timestamp": 1638223073041, "dataType": "Float", "metaData": {},              "properties": {                  "Quality": {                      "type": "Int32",                      "value": 192                 }             },              } }, "value": 12         }     1.23 } ],      "seq": 1   } }

  
  

  Anchor

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  NDATA

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  NDATA

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  NDATA

  The Device DDATA metrics array for the Edge Node NDATA message will contain the following:

  • The Sparkplug elements: Namespace, Group ID, Edge Node ID, Device ID.  They will be grouped under "topic" along with Message Type
  • A "timestamp" for when the payload was constructed
  • Any Device tags defined in the "Device folder that have changed
  • A message sequence number

  : 

  • Any tags defined in the Edge Node folder that have changed, For example if we write the value 10 to Tag 4

  
  

  Code Block
  title Edge Node DATA message
  {   "topic": {     "namespace": "spBv1.0",     "edgeNodeDescriptor": "G1/E1",     "groupId": "G1",     "edgeNodeId": "E1",     "type": "NDATA"   },   "payload": {     "timestamp": 1638223663812,     "metrics": [       {         "name": "Tag 4",         "timestamp": 1638223662800,         "dataType": "Int32",         "value": 10       }     ],     "seq": 2   } }

  
  

  Anchor
  DDATA DDATA

  DDATA

  The metrics array for the Device DDATA message will contain: 

  • Any tags defined in the Device folder that have changed, For example if we write the value 10 to Tag 1

  
  

  Code Block
  title Device DATA message
  {   "topic": {     "namespace": "spBv1.0", "edgeNodeDescriptor": "G1/E1",     "groupId": "G1",     "edgeNodeId": "E1",     "deviceId": "D1", "type": "DDATA"   },   "payload": {     "timestamp": 1638223663812,     "metrics": [       {         "name": "T1Tag 1",         "timestamp": 1638223662800,         "dataType": "INT32Int32",         "value": 10010       }     ],     "seq": 23   } }

  
  

  Anchor
  NDEATH NDEATH

  NDEATH

  The metrics array for the Edge Node DEATH message will contain:

  • A Birth/Death sequence number to track the Sparkplug session of the Edge client

  
  

  Code Block
  title Edge Node DEATH message
  { "topic": { "namespace": "spBv1.0", "edgeNodeDescriptor": "G1/E1", "groupId": "G1", "edgeNodeId": "E1", "type": "NDEATH" }, "payload": { "timestamp": 1638223073190, "metrics": [ { "name": "bdSeq", "timestamp": 1638223073187, "dataType": "Int64", "value": 5 } ] } }

  
  

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  DDEATH DDEATH

  DDEATH

  The metrics array for the DDEATH message will be empty.

  
  

  Code Block
  title Device DEATH message
  {   "topic": {       "namespace": "spBv1.0",       "edgeNodeDescriptor": "G1/E1",       "groupId": "G1",       "edgeNodeId": "E1",       "deviceId": "D1",       "type": "DDEATH

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  "   },   "payload": {     "timestamp": 1638223073192,     "metrics": []   } }

  
  

  
  

  
  

  Excerpt Include
  CLD80:FAQ: Ignition Modules CLD80:FAQ: Ignition Modules nopanel true

  Understanding and decoding Ignition QualityCodes