The OPC UA DI vocabulary

A device type of the Devices model (OPC 10000-100, "DI") keeps its process values in a ParameterSet, its methods in a MethodSet, and arranges both into FunctionalGroups such as Configuration or Maintenance, each organizing its members with one reference per member. The di: block says what the type is in DI, and the modeler writes that structure for you.

A di: block is a shorthand, not a new model: before compiling, the modeler expands it into the plain DSL it stands for, and the NodeSet2 is the same as if you had written that DSL by hand. You can add any plain key beside di:. The vocabulary comes with the DI extension of the modeler, in the CLI, the VS Code extension and the online editor.

The examples share this header:

namespaceUri: http://acme.com/UA/Pumps/
version: 1.0.0
publicationDate: "2026-10-10T00:00:00Z"
namespaces:
  - di

Its keys are the vocabulary's own words, in camelCase; a node is always an entry with its browseName, as everywhere else in the DSL, never a key.

A device type

PumpType
objectTypes:
  - browseName: PumpType
    description: A centrifugal pump, as a DI device.
    di:
      device:
        parameters:
          - browseName: Speed
            dataType: ua:Double
            engineeringUnits: revolutions per minute
            accessLevel: CurrentRead | CurrentWrite
          - browseName: Pressure
            dataType: ua:Double
            engineeringUnits: bar
          - browseName: OperatingHours
            dataType: ua:Double
        methods:
          - browseName: Start
          - browseName: Stop
        groups:
          - browseName: Operational
            members: [Speed, Pressure, Start, Stop]
          - browseName: Maintenance
            members: [OperatingHours]
        identification: [Manufacturer, Model, SerialNumber]
        nameplate: [ProductCode]

The kind, here device, picks the DI base type, used as subtypeOf unless the entry states one:

Kind	Base type
`device`	`di:DeviceType`: a field device, whose eight nameplate Properties are Mandatory
`component`	`di:ComponentType`: a part of a device, a module, a software component
`block`	`di:BlockType`: a function block
`topologyElement`	`di:TopologyElementType`: anything else with parameters and groups

Key	Writes
`parameters`	the Variables of `di:ParameterSet`, written as under `components:`
`methods`	the Methods of `di:MethodSet`, written as under `methods:`
`groups`	a FunctionalGroup per entry, organizing its `members`: parameters, methods or nameplate Properties by name, any other element by path (`/Range`). `optional: true` makes the group Optional
`identification`	the `di:Identification` group, organizing nameplate Properties (and parameters or methods if needed)
`nameplate`	Optional nameplate Properties made Mandatory, such as `ProductCode` or `ManufacturerUri`
`lock`	`true` makes the `di:Lock` (LockingServices) part of every instance

The well-known group names of OPC 10000-100 §4.4.2 (Configuration, Tuning, Maintenance, Diagnostics, Statistics, Status, Operational, OperationCounters) go to the DI namespace, as the specification asks: Operational above is di:Operational, and a client that knows DI recognizes it. Any other name, such as PumpCurve, stays in your namespace.

The same type in plain DSL

PumpType in plain DSL
objectTypes:
  - browseName: PumpType
    description: A centrifugal pump, as a DI device.
    subtypeOf: di:DeviceType
    components:
      - browseName: di:ParameterSet
        components:
          - browseName: Speed
            dataType: ua:Double
            engineeringUnits: revolutions per minute
            accessLevel: CurrentRead | CurrentWrite
          - browseName: Pressure
            dataType: ua:Double
            engineeringUnits: bar
          - browseName: OperatingHours
            dataType: ua:Double
      - browseName: di:MethodSet
        methods:
          - browseName: Start
          - browseName: Stop
      - browseName: di:Operational
        typeDefinition: di:FunctionalGroupType
      - browseName: di:Maintenance
        typeDefinition: di:FunctionalGroupType
      - browseName: di:Identification
        typeDefinition: di:FunctionalGroupType
    promotedToMandatory: [di:ProductCode]
    references:
      - { referenceType: ua:Organizes, source: /di:Operational, target: /di:ParameterSet/Speed }
      - { referenceType: ua:Organizes, source: /di:Operational, target: /di:ParameterSet/Pressure }
      - { referenceType: ua:Organizes, source: /di:Operational, target: /di:MethodSet/Start }
      - { referenceType: ua:Organizes, source: /di:Operational, target: /di:MethodSet/Stop }
      - { referenceType: ua:Organizes, source: /di:Maintenance, target: /di:ParameterSet/OperatingHours }
      - { referenceType: ua:Organizes, source: /di:Identification, target: /di:Manufacturer }
      - { referenceType: ua:Organizes, source: /di:Identification, target: /di:Model }
      - { referenceType: ua:Organizes, source: /di:Identification, target: /di:SerialNumber }

Conformant by construction

The DI rules of the modeler check the expanded type like any other, and the vocabulary leaves them nothing to find: a parameter can only land in ParameterSet (DSL-W-DI-001), a method in MethodSet (DSL-W-DI-002), and a group organizes members of its own type, named once (DSL-E-DI-003).

An instance

On an instance, the block takes values: the nameplate Properties and the parameters, each an entry with its browseName and value. The instance goes to DeviceSet, where DI clients look for Devices, unless the entry states its own placement.

Pump1 in DeviceSet
objectTypes:
  - browseName: PumpType
    di:
      device:
        parameters:
          - browseName: Speed
            dataType: ua:Double
            accessLevel: CurrentRead | CurrentWrite
instances:
  - browseName: Pump1
    typeDefinition: PumpType
    di:
      device:
        nameplate:
          - browseName: Manufacturer
            value: ACME Pumps
          - browseName: SerialNumber
            value: "2026-0042"
          - browseName: DeviceClass
            value: Pump
        parameters:
          - browseName: Speed
            value: 1450

Key	Writes
(placement)	`organizedBy: /ua:Objects/di:DeviceSet` when the entry states none
`nameplate`	`propertyValues:` of the nameplate Properties; an Optional one the type leaves out, such as `DeviceClass` above, is added to `optionals:` so that it exists to take its value
`parameters`	`initializers:` on `di:ParameterSet/<name>`

Mistakes

DSL-E-DI-101: a key the block does not know (an instance takes only values), or an instance without its typeDefinition.
DSL-E-DI-102: a group member that names nothing.
DSL-E-DI-103: a nameplate name that is not a DI nameplate Property, or on a type one that is not Optional on this kind.

A device type​

Conformant by construction​

An instance​

Mistakes​

A device type

Conformant by construction

An instance

Mistakes