7.3.8 Mapping of StdVariableRef and StdRecordItemRef

The StdVariableRefs (standard variable references) reference to standardized information, that is already defined in the IOLinkDeviceType. In Table 21, an overview of the mapping is given.

The StdRecordItemRefs (standard record item references) reference to standardized information, that is already defined in the IOLinkDeviceType. In Table 22, an overview of the mapping is given.

In both cases, the following rule applies.

If there is an InstanceDeclaration on the IOLinkDeviceType:

If the StdVariableRef or StdRecordItemRef is not defining a Button and the InstanceDeclaration is a Variable, the InstanceDeclaration shall be overridden in the new created type and referenced from all Objects representing IODD Menus having such a reference. If a default value is defined, the OPC UA Server shall use this as Value of the Variable, if several different default values are defined, the first one defined in the IODD shall be used. Other characteristics defined on the StdVariableRef of StdRecordItemRef are ignored.

For VendorID and DeviceID there are two resp. three StdRecordItemRefs used. In the mapping, whenever an IODD Menu references at least one of them, the whole Variable (VendorID or DeviceID) is referenced.

If the StdVariableRef or StdRecordItemRef is defining a Button, the rules defined in 7.3.7 apply.

If there is no InstanceDeclaration on the IOLinkDeviceType defined, the same rules as for VariableRef and RecordItemRef defined in 7.3.6 and 7.3.7 apply.

Note that for V_SystemCommand the mapping described in this section applies, although there is a representation in the IOLinkDeviceType (SystemCommand Method), because the IODD provides useful new information about the supported system commands.