Standard Variable Types |
This topic contains the following sections:
- BaseVariableType
- PropertyType
- BaseDataVariableType
- ServerVendorCapabilityType
- DataTypeDictionaryType
- DataTypeDescriptionType
- ServerStatusType
- BuildInfoType
- ServerDiagnosticsSummaryType
- SamplingRateDiagnosticsArrayType
- SamplingRateDiagnosticsType
- SubscriptionDiagnosticsArrayType
- SubscriptionDiagnosticsType
- SessionDiagnosticsArrayType
- SessionDiagnosticsVariableType
- SessionSecurityDiagnosticsArrayType
- SessionSecurityDiagnosticsType
Typically, the components of a complex VariableType are fixed and can be extended by subtyping. However, because each variable of a VariableType can be extended with additional components the OPC Unified Architecture specification allows the extension of the standard VariableTypes defined in this document with additional components. This allows the expression of additional information in the type definition that would be contained in each Variable anyway. However, it is not allowed to restrict the components of the standard VariableTypes defined in this part. An example of extending VariableTypes would be putting the standard Property NodeVersion, defined in section Address Space, into the BaseDataVariableType, stating that each DataVariable of the server will provide a NodeVersion.
BaseVariableTypeThe BaseVariableType is the abstract base type for all other VariableTypes. However, only the PropertyType and the BaseDataVariableType directly inherit from this type.
There are no References, except for HasSubtype References, specified for this VariableType.
PropertyTypeThe PropertyType is a subtype of the BaseVariableType. It is used as the type definition for all Properties. Properties are defined by their BrowseName and therefore they do not need a specialised type definition. It is not allowed to subtype this VariableType. There are no References specified for this VariableType.
BaseDataVariableTypeThe BaseDataVariableType is a subtype of the BaseVariableType. It is used as the type definition whenever there is a DataVariable having no more concrete type definition available. This VariableType is the base VariableType for VariableTypes of data variables, and all other VariableTypes of data variables shall either directly or indirectly inherit from it. However, it might not be possible for servers to provide all HasSubtype References from this VariableType to its subtypes, and therefore it is not required to provide this information.There are no References except for HasSubtype References specified for this VariableType.
ServerVendorCapabilityTypeThis VariableType is an abstract type whose subtypes define capabilities of the server. Vendors may define subtypes of this type.
DataTypeDictionaryTypeData type dictionaries are defined in section Address Space. This VariableType is used to represent the type of the data type dictionaries. There are no references specified for this VariableType.
DataTypeDescriptionTypeData type descriptions are defined in section Address Space. This VariableType is used as the type for the data type descriptions. There are no references specified for this VariableType.
ServerStatusTypeThis complex VariableType is used for information about the server status. Its data variables reflect its DataType having the same semantic.
BuildInfoTypeThis complex VariableType is used for information about the server status. Its data variables reflect its DataType having the same semantic.
ServerDiagnosticsSummaryTypeThis complex VariableType is used for diagnostic information. Its data variables reflect its DataType.
SamplingRateDiagnosticsArrayTypeThis complex VariableType is used for diagnostic information. For each entry of the array, instances of this type will provide a Variable of the SamplingRateDiagnosticsType VariableType having the sampling rate as BrowseName.
SamplingRateDiagnosticsTypeThis complex VariableType is used for diagnostic information. Its data variables reflect its DataType.
SubscriptionDiagnosticsArrayTypeThis complex VariableType is used for diagnostic information. For each entry of the array, instances of this type will provide a Variable of the SubscriptionDiagnosticsType VariableType having the SubscriptionId as BrowseName.
SubscriptionDiagnosticsTypeThis complex VariableType is used for diagnostic information. Its data variables reflect its DataType.
SessionDiagnosticsArrayTypeThis complex VariableType is used for diagnostic information. For each entry of the array instances of this type will provide a Variable of the SessionDiagnosticsVariableTypeVariableType, having the SessionDiagnostics as BrowseName. Those Variables will also be referenced by the SessionDiagnostics.
SessionDiagnosticsVariableTypeThis complex VariableType is used for diagnostic information. Its data variables reflect its DataType.
SessionSecurityDiagnosticsArrayTypeThis complex VariableType is used for diagnostic information. For each entry of the array instances of this type will provide a Variable of the SessionSecurityDiagnosticsType VariableType, having the SessionSecurityDiagnostics as BrowseName. Those Variables will also be referenced by the SessionDiagnostics Objects.. Since this information is security related, it should not be made accessible to all users, but only to authorised users.
SessionSecurityDiagnosticsTypeThis complex VariableType is used for diagnostic information. Its data variables reflect its DataType. Since this information is security-related, it should not be made accessible to all users, but only to authorised users.