🤔 I thought about if it could make sense to connect to a MQTT broker and write the topic-path in a structured and connected way to a graph database. It could reflect a companies UNS with ISA structure in a graph with query possibilities.
🤝 The UNS could be enriched by adding additional meta information to the database and be linked to the MQTT nodes. Graph queries could be used to combine the enriched data with the current values of the machines…
👉 I reactivated the Neo4J Logger in the Automation-Gateway.com, and enabled MQTT for it. It creates the nodes in a neo4j graph database based on the incoming MQTT messages.
At startup it can also write the OPC UA node structure into the graph database, so that the basic model of the OPC UA server is mirrored to the graph database. For that you have to add the “Schemas” section in the config file (see an example configuration file below). There you can choose which RootNodes (and all sub nodes) of your OPC UA systems should be mirrored to the graph database.
Once you have the (simplified) OPC UA information model in the graph database, you can add on top of that your own knowledge graph data and create relations to OPC UA nodes of your machines to enrich the semantic data of the OPC UA model.
With that model you can leverage the power of your Knowledge Graphs in combination with live data from your machines and use Cypher queries to get the knowledge out of the graph.
Here we see an example of the OPC UA server from the SCADA System WinCC Open Architecture. The first level of nodes below the “Objects” node represent Datapoint-Types (e.g. PUMP1) followed by the Datapoint-Instances (e.g.: PumpNr) and below that we see the datapoint elements (e.g. value => speed). An datapoint element is an OPC UA variable where we also see the current value from the SCADA system.
Example Gateway configuration file:
Database:
Logger:
- Id: neo4j
Enabled: true
Type: Neo4j
Url: bolt://nuc1.rocworks.local:7687
Username: "neo4j"
Password: "manager"
Schemas:
- System: opc1 # Replicate node structure to the graph database
RootNodes:
- "ns=2;s=Demo" # This node and everything below this node
- System: winccoa1 # Replicate the nodes starting from "i=85" (Objects) node
WriteParameters:
BlockSize: 1000
Logging:
- Topic: opc/opc1/path/Objects/Demo/SimulationMass/SimulationMass_Float/+
- Topic: opc/opc1/path/Objects/Demo/SimulationMass/SimulationMass_Double/+
- Topic: opc/opc1/path/Objects/Demo/SimulationMass/SimulationMass_Int16/+
- Topic: opc/winccoa1/path/Objects/PUMP1/#
- Topic: opc/winccoa1/path/Objects/ExampleDP_Int/#
