The information model for Weighing Technology has three main aspects: the generic part for all scale devices, the production management and the scale type specific part.
Figure 10 shows an overview of the different ObjectTypes for the Weighing Technology devices and the references to the types from the Companion Specification for devices. Four subtypes of the ComponentType are defined:
The entrypoint of a server is an instance of the ScaleSystemType or a ScaleDeviceType. The ScaleSystemType represents a multi-scale system and includes one ore more scales and has some common information (e.g. serial number). The ScaleDeviceType is abstract and only subtypes of it can be instantiated (see section 7.3). Both Types (ScaleDeviceType and ScaleSystemType) can optionally have an Object of the ProductionPresetType (see section 8.7) and/or an Object (called ProductionOutput) of the StatisticType.
Figure 10 shows the most important Object types used in the information model and the relations between them.
Figure 10 – Notation Overview of the OPC UA Weighing Technology information model
A modular scale device is represented by a (subtype of) ScaleDeviceType or ScaleSystemType that is composed of a top-device and a set of subdevices (modules). It uses the modular devices concept of OPC UA Companion Specification for Devices (see OPC 10000-100 9.2). The modules (subdevices) of modular scale devices are aggregated in the SubDevices Object . The SupportedTypes folder for SubDevices is used to maintain the set modules that can be added to the ScaleDevice or scale system(see Figure 11).
Figure 11 – Modular scale devices and scale systems
This Companion Specification defines the following supported types (including the subtypes) for the ScaleDeviceType:
This Companion Specification defines the following supported type (including the subtypes) for the ScaleSystemType:
- ScaleDeviceType
The SupportedTypes folder may only refer to a subset of all possible subdevices for the modular device. Other vendor-specific modules or modules of other Companion Specifications can be defined. For more details of the concepte see OPC 10000-100.
In the information model different subtypes of a ScaleDeviceType are defined for the different scale types (see section 5.1.2). For many subtypes of the ScaleDeviceType, a subtype of the ProductType exists as a counterpart. The ProductFolder defined in the ScaleDeviceType is overload and can only contain the specific subtype of the ProductType or a subtype of them.
Figure 12 shows the main Object types used in the information model and the relations between them.
Figure 12 – Overview of the scale types in the information model