Table 60 describes the required content of the RefMeta element and its Meta child elements describing a Data Object.
Table 60 – RefMeta child elements
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<RefMeta Prefix=“opc http://opcfoundation.org/PNGSDGM/”> |
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Child element |
Property attribute of child element |
Required Content attribute of child element |
Mandatory/Optional |
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<Meta> |
opc:Name |
Brief denomination of the Data Object, e.g. “Discharge Temperature”, “Ambient Pressure” and the like. |
M |
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<Meta> |
opc:EngineeringUnit |
Mapped UNECE code of the 0:EUInformation data type (see [OPC 10000-8], 5.6.3) representing the engineering unit of this Data Object. |
O |
|
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<Meta> |
opc:EURange |
Upper and lower engineering unit boundary of the data value in the format “<upper>;<lower>”. Represent with 0:Range type Property as part of an AnalogUnitRangeType Variable representing the Data Object. For numeric data only. Specify only in conjunction with “opc:EngineeringUnit”. |
O |
|
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<Meta> |
opc:FunctionGroupName |
Path name for the OPC UA 2:FunctionalGroupType container object which shall be created by an OPC UA Server for the object representing the Data Object. The path names provided for the Data Objects can define a folder hierarchy using file system path syntax: <parent folder/subfolder 1/../subfolder n>. The RefMeta element of one Data Object may contain this Meta element more than once. If so, the representing OPC UA Variable becomes a component of different container Objects. |
O |
|
|
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<Meta> |
opc:DataMapping |
Desired OPC UA representation for the Data Object: “Variable” or “Property”. If no “Meta” element with this attribute is provided, the representation defaults to “Variable”. |
O |
|
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<Meta> |
opc:Offset |
Calculation factor to be applied by an OPC UA Server to obtain the actual display value in the Information Model. To be used in conjunction with the “opc:Gradient” Meta element, see below. |
O |
|
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<Meta> |
opc:Gradient |
Calculation factor to be applied by an OPC UA Server to obtain the actual display value in the Information Model. To be used in conjunction with the “opc:Offset” Meta element, see above. Regardless of the referenced Data Object’s data type specified by the parent “Ref” element, if “opc:Offset” and “opc:Gradient” Meta elements are provided, the DataType in the Information Model shall always be 0:Float or 0:Double. The display value shall always be calculated asValue = (value read from Device * Gradient) + Offset. |
O |
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<Meta> |
opc:DestinationDataType |
Name of the OPC UA base data type to be used as DataType for the Variable or Property which represents the data value in the Information Model, e.g. “0:UInt16”. Overrides the mapping defined in Table 58. |
O |
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As shown in Figure 15, the “ParameterRecordDataItem” elements may contain an optional “RecordMeta” element. The schema defined for the “RecordMeta” element is the same as the schema of the “RefMeta” elements (see Figure 20 also). Table 61 shows the required content of the optional RecordMeta element.
One “RecordMeta” child element as described in Table 61 specifying the recommended polling interval may be part of the “ParameterRecordDataItem” element.
Table 61 – RecordMeta child element for Data Objects
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<RecordMeta Prefix=“opc http://opcfoundation.org/PNGSDGM/”> |
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Child element |
Property attribute of child element |
Required Content attribute of child element |
Mandatory/Optional |
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<Meta> |
opc:UpdateRate |
Recommended polling interval for the Data Object, in milliseconds. The Server may deviate from the specified update interval according to local bandwidth requirements. |
M |
|
If Base Mode Parameter Access is supported, a “ParameterRecordDataItem” with “Index” attribute containing the record index to use for the BMP protocol (usually “0xB02E”) and a “RecordMeta” child element containing a “Meta” child element with “Property” attribute equal to “opc:BMPChannel” as described in Table 62 can be used to specify BMPs. The vendor specific options for the representation of BMPs in the Information Model are specified using a sequence of “RefMeta” elements (see Table 63), as shown in the GSDML sample in E.1.
The “Length” attribute of the “ParameterRecordDataItem” element is mandatory but may be ignored by Servers since the size of the memory needed varies dependent on the actual request response. Servers must follow the protocol as defined in [PDP], chapter 6.2.3 “Base Mode Parameter Access” (see GSDML sample in E.1 also). Table 63 shows the required content of the “RefMeta” child element specifying one BMP.
Table 62 – RecordMeta child element for BMPs
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<RecordMeta Prefix=“opc http://opcfoundation.org/PNGSDGM/”> |
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Child element |
Property attribute of child element |
Required Content attribute of child element |
Mandatory/Optional |
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<Meta> |
opc:BMPChannel |
Brief function description, e.g. “ControlUnit”.Remark: The parent ParameterRecordDataItem element shall specify the record number to be used for BMP Access. |
M |
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Table 63 – RefMeta child element for BMPs
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<RefMeta Prefix=“opc http://opcfoundation.org/PNGSDGM/”> |
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|
Child element |
Property attribute of child element |
Required Content attribute of child element |
Mandatory/Optional |
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<Meta> |
opc:ParameterNumber |
Parameter number (see [PDP], 6.2.3 “Base Mode Parameter Access”) identifying the parameter to be represented in the Information Model. |
M |
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<Meta> |
opc:FunctionGroupName |
Path name for the OPC UA 2:FunctionalGroupType container Object which shall be created by an OPC UA Server for the Variable representing the BMP Data Object. The path names can define a folder hierarchy using file system path syntax: <parent folder/subfolder 1/../subfolder n>. If missing, the Variable shall be created under root level as children of the GsdGenSubmoduleApplicationType Object. The RefMeta element of one BMP may contain this Meta element more than once. If so, the representing OPC UA Variable becomes a component of different container Objects. |
O |
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<Meta> |
opc:UpdateRate |
Recommended polling interval in milliseconds for the parameter. |
O |
|
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<Meta> |
opc:DestinationDataType |
One of the following: “Enumeration”, “ArrayFolder”, “OptionSetVariable”. “Enumeration”: Shall only be specified for “simple” BMPs with assigned text array (see [PDP], 6.2.1.4). The BMP shall be represented using a 0:Enumer ation DataType created by the Server as described in chapter 6.7.1. “ArrayFolder”: Shall only be specified for “array” BMPs with assigned text array (see [PDP], 6.2.1.4). The BMP shall be represented as “array folder” as described in chapter 6.7.1. “OptionSetVariable”: Shall only be specified for “V2” parameters with assigned text array (see [PDP], 6.2.1.4). The BMP shall be represented as 0:OptionSetType as described in chapter 7.1. |
O |
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