OPC UA

Miravo’s OPC UA adapter projects the asset graph into a typed OPC UA address space. OPC UA is opt-in — enable it with --opcua.

Getting Started

miravo start --template smart-factory --opcua

Connect any OPC UA client (UaExpert, Prosys, Kepware) to:

opc.tcp://localhost:4840/miravo

Address Space Structure

The browse path hierarchy maps directly to OPC UA nodes:

Root/Objects/
  MiravoWorks (FolderType)
    smart-factory (FolderType)
      production (FolderType)
        line-1 (FolderType)
          centrifugal-pump-001 (Object, typeDefinition: centrifugal-pump)
            rpm (Variable, Double, AccessLevel: CurrentRead)
            speed_command (Variable, Double, AccessLevel: CurrentRead|CurrentWrite)
            serial_number (Property, String, AccessLevel: CurrentRead)
            Start (Method)
            Stop (Method)

Node Types

Model concept	OPC UA mapping
Path segments	FolderType nodes
Asset instance	Object with HasTypeDefinition
Variable member	Variable (componentOf instance)
Property member	Property (propertyOf instance, read-only)
Method	Method node with typed arguments

Type Mapping

Miravo Data Type	OPC UA DataType
Double	DataType.Double
Float	DataType.Float
Int32	DataType.Int32
UInt16	DataType.UInt16
UInt32	DataType.UInt32
Boolean	DataType.Boolean
String	DataType.String

Access Levels

Model Access	OPC UA AccessLevel
read	CurrentRead
readwrite	CurrentRead + CurrentWrite
write	CurrentWrite

Properties are always read-only regardless of declared access.

Engineering Units

Members with unit metadata get OPC UA EUInformation nodes. Members with eu_range get EURange nodes. This allows OPC UA clients to display proper units and scaling.

Methods

Model methods with runtime metadata are executable from OPC UA clients. Input and output arguments are typed and follow the declaration order in the model.

Use any OPC UA client (UaExpert, Prosys, or opcua-commander) to call a method:

1. Browse to the instance node (e.g., centrifugal-pump-001)
2. Select the method (e.g., SetSpeed)
3. Provide input arguments in declaration order (e.g., speed_rpm: 900)
4. Execute — the engine applies the method and returns the output arguments

Methods without a runtime block appear in the address space for browsing but return an error if called.

Configuration

Option	Env Var	Default	Description
--opcua	—	Disabled	Enable OPC UA server
--opcua-port	MIRAVO_OPCUA_PORT	4840	Server port
--opcua-host	MIRAVO_OPCUA_HOST	0.0.0.0	Server bind host

Advanced tuning:

Env Var	Default	Description
MIRAVO_OPCUA_WRITE_BUDGET	8192	Max address space writes per drain cycle (512-65536)

Running Multiple Protocols

MQTT and OPC UA can run simultaneously from the same simulation, and additional protocols (Modbus TCP, Sparkplug B) are on the roadmap:

miravo start --template smart-factory --opcua

This starts MQTT on port 1883 and OPC UA on port 4840. All adapters read from the same asset graph on each tick. The data is consistent across protocols.

Runtime Management

Enable or disable OPC UA while the simulation is running:

Enable OPC UA:

miravo adapter enable opcua --port 4840

Disable OPC UA:

miravo adapter disable opcua