This section briefly introduces the multi-level document structure of the OPC UA Companion Specification Mining. The multi-level document structure is shown Figure 1. From this figure it becomes apparent, that the companion specification’s structure follows a three-level hierarchy. Every document in this hierarchy corresponds to precisely one OPC UA information model. Notably, the document hierarchy reflects the direction of type inheritance in this companion specification. Examples of this inheritance pattern are given further below.
The document numbering of the OPC UA Companion Specification Mining ranges from 40560 to 40569. Parts 40561 to 40569 make use of a multi-part numbering scheme, meaning these documents consist of sub-parts. For example, part 40561-1 and 40561-2 are sub-parts of 40561. Furthermore, the parts 40561 to 40568 are used to classify similar type of mining machines and systems into disjunct groups which are structured regarding the core process steps of mining. The machines are integrated into this structure according to the main task performed by the machine. For instance, loading machines, such as hydraulic excavators or mining shovels, are classified to be sub-part documents of the OPC 40562 Loading Equipment multi-part document. Within the OPC UA Companion Specification Mining, there are nine such multi-part documents which are presented in Annex B as machine- and system-category-level documents. Figure 2 shows the relationship between the automation pyramid and the document structure, illustrating the possibility of integrating horizontal and vertical communication elements within the OPC UA Companion Specification Mining. The Numbering of the different machine level categories is based on the mining core process steps beginning with extraction.
By definition, the first sub-part of any multi-part document, e.g. OPC 40561-1, 40562-1 or 40567-1, serves as an introduction to a set of similar type of mining machinery or systems and therefore defines parent types common to all such machines and systems. For instance, the Hydraulic Excavator machine, as defined by the HydraulicExcavatorType in OPC 40562-2, makes use of some methods, variables etc. of a parent type, called LoadingMachineType, that is defined in the machine-category document OPC 40562-1. The Hydraulic Excavator is defined as loading equipment even if it is also used for extraction purposes. The main criteria of classification depend upon the main purpose of a machine, which is loading in case of the Hydraulic Excavator. An overview of the existing multi-part documents is provided in Annex B.
Following the same logic as above, the industry-level document OPC 40560 at the top of the hierarchy in Figure 1 defines terms, types and conventions used throughout and available to all subsequent machine-category- and machine-level documents. An example of this inheritance pattern is the abstract MiningEquipmentTyp, as defined in Chapter 7.1 of this document, which serves as a parent type for any machine-level types.
One exception to the above stated rules is OPC 40569 which describes the Application and Use Cases of the machines and systems covered in this Companion Specification.