Constraint Block Definition Diagram (BDD)

 

The constraint BDD is similar to the BDD. Rather than composition or classification, the constraint BDD shows the ConstraintDefinitions (constraint expression) used to constrain the subject entity (component) of your system. The constraint block will include the constraint expression (an expression that must evaluate to either true or false and is most likely an equation or inequality used to constrain value properties of blocks) and the independent and dependent variables that constitute the constraint parameters. Constraint parameters receive their values from the value properties they are bound to or being constrained by. The constraint BDD does not convey which constraint parameters and value properties are bound to one another. This is expressed in the associated Parametric diagram.

 

The constraint block definition diagram (BDD) is available for entities in the Component class (as well as any other subclasses of ImplementationUnit), Function class (as well as other subclasses of ProcessingUnit), Item class (as well as other subclasses of InformationUnit), Link class (as well as other subclasses of ConnectingUnit), Package (and subclasses).

 

 

The BDD uses a structured layout with specific movement rules for each node.

Toolbox Properties Tab

In addition to the classic diagram options, the Constraint BDD settings include:

• Levels - controls the initial number of levels to show on the diagram. Individual nodes can then be expanded or collapsed, as desired.
• Use Orthogonal Lines - controls whether orthogonal lines or direct lines are used to connect nodes on the diagram.
• Show Role Names - controls whether the part role for the node is shown on the diagram.
• Show Relationship Labels - controls whether the relationship names are shown on the diagram.

 Toolbox

The constructs and key entities tabs allow you to quickly develop your block definition, while the All entities Tab enables you to relate your blocks to the remainder of your system definition.

 

Constructs

• New Constraint Definition - drop onto any diagram node to create a new block (component) inherited from the node (included in)
• Constraint Definitions - drop onto any diagram node to relate an existing block (component) inherited from the node (included in)
• New Parameter - drop onto a constraint node to create a new connection to an entity whose parameter will be used
• Parameters - drop onto any diagram to relate an existing entity whose parameter will be used

Utilities

• Image - drop onto the diagram to insert a new picture
• Note - drop onto the diagram to insert a new note (descriptive text in a note icon)
• Shapes - drop onto the diagram to insert a new shape (a rectangle, rounded rectangle, circle, or ellipse with text, if desired)

 Key Entities

• Component - drop an existing Component on the diagram as either a constrained entity or entity where a parameter is used
• ConstraintDefinition - drop an existing constraint definition on the diagram
• Function - drop an existing Function on the diagram as either a constrained entity or entity where a parameter is used
• Item - drop an existing Item on the diagram as either a constrained entity or entity where a parameter is used 
• Link -drop an existing Link on the diagram as either a constrained entity or entity where a parameter is used
• Mitigation Activity - drop a MitigationActivity that lessens the effects of a bad result on the diagram
• Product -drop an existing Product on the diagram as either a constrained entity or entity where a parameter is used
• ProgramActivity -drop an existing ProgramActivity on the diagram as either a constrained entity or entity where a parameter is used
• TestItem -drop an existing TestItem on the diagram as either a constrained entity or entity where a parameter is used
• VerificationActivity -drop an existing VerificationActivity on the diagram as either a constrained entity or entity where a parameter is used

All Entities - all classes and entities in the system model, allowing you to drag any entity on top of a diagram node to establish relationships with the balance of your system model

Context Menu Commands

• Rename

• Renumber

• Set Attribute

• Remove

• Delete

• Hide

• Edit Constraint Definitions

• Edit Parameters

• Sort Block

• Expand Nodes

• Collapse Nodes

• Arrange

• • Bring To Front

  • Bring Forward

  • Send Backward

  • Send To Back

• Open Entity

• Submenu listing entities

• Select Matching Nodes

• Layout Selections

 

Tips and Tricks

To communicate the full technical depth of the block structure, block definition diagrams classically include far more content per node than other diagrams. Make liberal use of the ability to specify different icon templates for each node, using more complete templates where operations/values/ports are desired and lesser templates where they are not. Not only does this tighten the diagram, it helps focus attention on the critical aspects you are seeking to emphasize.