In a Concurrent Design activity design parameters are exchanged between the active domains that are together [developing an engineering model]Develop_EM]. These parameters are often (physical) parameters that describe or use quantities that have scales and units associated with them. The parameters are created based on a definition of a Parameter Type. The concepts of Measurement Units, Measurement Scales and Parameter Types, as well as additional concepts, are managed in Reference Data Libraries (RDLs).
To be able to create the definition of various Parameter Types, the measurement scales and measurement units that are needed to describe a variety of parameters have to be created first if not yet available. The CDP™ implementation contains an extensive set of definitions for Measurement Units, Measurement Scales and (QantityKind) Parameter Types. These definitions are given by the ECSS-E-TM-10-25 guideline that uses as a basis the International System of Quantities (ISQ) and the International System of Units as defined in ISO/IEC 80000. In addition measurement scales are explicitly defined, so that a fully self-described system is captured. Where needed this is extended with non-SI quantities, scales and units with explicit conversion relationships.1
These provide a large set of descriptions for SI base and SI derived units and quantities. They can be created and managed at the level of the CDP™. These items can also be created for the level of the activity, but these are then transferred to the CDP™ level. All new items that are created in the RDL can thus be viewed and used in other activities.
A top-level Site RDL
Provides generally used concepts such as generic ParameterTypes, SI QuantityKinds, MeasurementScales and MeasurementUnits. These are concepts that are used in almost any concurrent design EngineeringModel independent of the application domain.
A second-level Site RDL
Holds concepts like ParameterTypes, MeasurementScales, MeasurementUnits and Glossaries for a specific application domain or "family of studies", for example: Space Mission Development, System of Systems Development, Early Concept Development, Payload Instrument Development, Launch Vehicle Development.
A third-level Model RDL
Contains concepts similar to the second level, but now those that are particular to a specific EngineeringModel.
The top-level Site RDL of a data source is available from the installation of e.g. an OCDT PDS and OCDT WSP or a CDP™ Back-End and CDP™ Web Services as ECSS-E-TM-10-25 compliant data sources. All other RDLs, both second-level Site RDLs as well as Model RDLs have a relationship to this top-level RDL. Subsequent changes to this Site RDL can be made, e.g. creating additional items. The details are described in the separate topics of units, scales, and parameter types. These changes will be updated to and available in all the engineering models on that connected data source.
It is also possible to create any number of additional second-level Site RDLs, e.g. to create RDLs for specific types of projects. These are created essentially as branches from the top-level RDL; see below for a description of dependencies between RDLs and their use in engineering models.
Open the Site RDL Browser, navigate to the Directory ribbon tab and select the Reference Data Libraries icon to manage Site RDLs. This will open the browser that contains a list of all the Site RDLs available in the specified data source. The data source of the presented information of the Site RDL is displayed in the header area of the browser, as well as the first name and surname of the person.
A description of the available functionalities is given below. Next to these it is possible to use the generic functionality using the Search and Help icons. To make sure the latest data is shown in the browser, it is always possible to refresh it using the Refresh icon.
To create a new Site Directory RDL, select the Create a Site RDL icon or in the context menu select Create a Site RDL.
Provide a Name, Short Name, and choose a Required RDL for the Site Reference Data Library, and click Ok.
To edit a Site Directory RDL, select the Edit Site Reference Data Library icon or in the context menu select Edit.
Edit the Name and/or Short Name of the Site Reference Data Library, and click Ok.
To inspect a Site RDL, select the Inspect Site Reference Data Library icon or in the context menu select Inspect. In the Inspect modal dialog, all the details can be seen on the Basic tab. Additionally the status of the Site RDL is given by the check box for Deprecated, see the description of Delete below.
The Advanced tab provides information that may be useful mostly to CDP™ database administrators. Given are the UniqueID and the [Revision Number][Rev_Num].
To delete a Site RDL, select the Delete Site Reference Data Library icon or in the context menu select Deprecate. Items from the CDP™ are never completely deleted, but they are marked as Deprecated. This Deprecated status is an indication to users that it should not be used anymore.
To export a Site RDL, select the Export Site Reference Data Library icon or in the context menu select Export.
Next to the Site RDLs, following ECSS-E-TM-10-25 as the third level RDLs given above, for each CDP™ Activity, i.e. for each engineering model, a Model RDL is being created. Adaptations and extensions can be made to the RDL of the specific engineering model without the risk of compromising any other engineering models; see the section below however for dependencies between RDLs and engineering models.
The Reference Data of Measurement Units, Measurement Scales and Parameter Types in the RDL are defined at the level of the CDP™ or at the level of a specific engineering model. All new items that are created in a Site RDL can be viewed and used in other activities. This means that the RDL should be carefully managed. In managing the RDL, care has to be taken to create combinations of measurement units, measurement scales and parameter types that lead to meaningful definitions for parameters that are needed in the design work in the engineering models, and trying to avoid incorrect, ambiguous or duplicate definitions.
Editing entries in the RDL can have a large impact on not only the current activity, but also on all the other activities using it.
When a new Site RDL is created, a link is kept between the parent Site RDL(s) and the newly created Site RDL. When an engineering model is being created, an applicable Reference Data Library has to be selected for it from the Site RDLs.
It is advisable to avoid negatively affecting other CD activities and engineering model setups inadvertently by careful management of the measurement units, measurement scales and parameter types by a restricted group of users.
Last modified 1 year ago.