7 OPC UA ObjectTypes ToC Previous Next

7.3 ObjectTypes generated based on IODDs ToC Previous Next

7.3.9 Mapping of ProcessDataCollection and ProcessDataRefCollection ToC Previous Next

The ProcessDataCollection gives an interpretation of the input and / or output process data.

For each entry of the collection (IODD ProcessData) having an IODD ProcessDataOut of type ProcessDataItemT, for each IODD ProcessDataOut, a new sub-variable of the OPC UA Variable ProcessDataOutput is created, having the BrowseName composed of the ProcessData id and the ProcessDataItem id (“<ProcessData id> <ProcessDataItem id>”). If the ProcessData has a Condition, the Variable becomes optional, otherwise mandatory. In order to add a sub-variable to the ProcessDataOutput Variable defined on the IOLinkDeviceType, the ProcessDataOutput Variable needs to be overridden on the new created IODD-based subtype.
For each entry of the collection (IODD ProcessData) having a ProcessDataIn of type ProcessDataItemT, for each ProcessDataIn, a new sub-variable of ProcessDataInput is created, having the BrowseName composed of the ProcessData id and the ProcessDataItem id (“<ProcessData id> <ProcessDataItem id>”). If the ProcessData has a Condition, the Variable becomes optional, otherwise mandatory. In order to add a sub-variable to the ProcessDataInput Variable defined on the IOLinkDeviceType, the ProcessDataInput Variable needs to be overridden on the new created IODD-based subtype.

In both cases the DisplayName shall be the Name element of the ProcessDataItem. Localization should be considered. The DataType is chosen for the Datatype element or DatatypeRef element according to section 12.

The ProcessDataRefCollection can provide additional characteristics for the created Variables, like unitCode and displayFormat. Note that the optional ProcessDataRefCollection and its child elements are not supported by IODD Specification Version 1.0.1.

If the ProcessDataRef contains a unitCode the Variable shall have the Property EngineeringUnits as mandatory. The value shall be as defined in the ProcessDataRef (see Annex C).

If the ProcessDataRef contains a displayFormat the Variable shall have the Property DisplayFormat (see 13.6) as mandatory. The value shall be as defined in the ProcessDataRef.

In Figure 19 an example is shown on how to map an IODD ProcessDataCollection.

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Figure 19 – Example on how to map IODD ProcessDataCollection

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