Figure 19 shows the schema of the “AvailableRecordDataList” XML elements in the GSDML. The “AvailableRecordDataList” element contains “RecordDataRef” elements referencing “ParameterRecordDataItem” elements in the “ApplicationProcess/RecordDataList”(see [GSDML], 8.9.4).
The record must be readable from the referencing Submodule with the record index found in the “Index” attribute of the “ParameterRecordDataItem” element. Vendors might allow write access also using the “Access” attribute of the “ParameterRecordDataItem” element (see [GSDML]). Elements used for parameterization (“Access” attribute contains “prm” or is not present) represent Parameter records (see 6.6) and are not represented as Data Objects.
Additional properties needed for Data Objects are described by “RefMeta” and “RecordMeta” child elements of the “ParameterRecordDataItem” elements. Figure 20 shows the XML schema defined for the “RefMeta” and “RecordMeta” elements.
The “MetaExtensionT” schema describes a way to enhance certain elements in the GSDML with content which is defined in a different specification. For the description of Data Objects, the “Ref” elements may be extended with a “RefMeta” child element. The “RefMeta” element shall have a “Prefix” attribute and “Meta” child elements as shown in the following XML snippet.
<RefMeta Prefix="<tag> <URI>">
<Meta Property="tag:<property name>" Content="<property content>"/>
The content of the ”Prefix” attribute of the “RefMeta” element defines a tag name and the URI of the specification responsible for the definition of the required content of “Meta” child elements. The tag is used as prefix for the content of the “Property” attribute of all “Meta” child elements which are defined by the associated specification (see [GSDML], 8.28.1 “MetaExtension”).
The Object representing the Submodule offering Data Objects in the PROFINET aspect of the Information Model relates to the GsdGenSubmoduleApplicationType Object providing the Variables and Properties for these Data Objects using the 0:RepresentsSameFunctionalityAs ReferenceType.
Figure 21 – Mapping of XML elements describing Data Objects
The default VariableType for representing parameters obtained using Base Mode Parameter Access shall be 0:BaseDataVariableType. The Base Mode Parameter (BMP) data record is specified using a “RecordMeta” child element of the “ParameterRecordDataItem” element. The individual BMPs and their representation in the Information Model are specified using RefMeta elements, see C.2 for details.
“Simple” BMPs with assigned text array (see [PDP], 126.96.36.199) can be represented by a 0:Enumeration DataType created by the Server, as shown in Figure 22. The array elements are assigned to the fields of the 0:EnumValueType structure as specified in Table 20. The representing Variable shall have the TypeDefinition 0:BaseDataVariableType and the Value shall have the 0:Enumeration DataType created as described above. The BMP Name (see Table 65) shall be used as part of the BrowseName, see 7.1, EnumerationVariable.
“Array” BMPs with assigned text array (see [PDP], sec. 188.8.131.52) can be represented by a folder Object with Variables as components, as shown in Figure 23. The BMP Name (see Table 65) shall be used as BrowseName of the parent folder Object. If the BMP has assigned engineering units and range, the folder Object shall have a 0:EUInformation and a 0:Range Property. The elements of the assigned text array shall be used as BrowseNames of the 0:BaseDataVariableType Variables representing the array elements. There shall be as many Variables as are needed to represent all array elements. Each Variable Value receives the array element value which has the same index as the assigned text array element which is used as BrowseName.
The intended usage of folder Objects is the representation of “small” array BMPs with assigned text array if the sequence is not of importance. This allows Clients to access array elements in the same way as elements of associative arrays using the assigned texts, since an array element is selected by a text identifier. For example, the first element would have the BrowsePath “<BMP Name>/<BMP Text Array >”.
Figure 23 – BMP array parameter with assigned text array
Vendors can specify the desired representation of BMPs by providing “Meta” elements in the GSDML, as described in C.2. See the description of the <EnumerationVariable>, <OptionSetVariable> and <ArrayFolder> placeholders in 7.1 for details.