Parametric Diagrams

Parametric Diagrams (par) = used to express information about system’s constraints. Recall that a constraint block = special kind of block that encapsulates constraint expression; equation or inequality. This enables the following abilities:

– Specify assertions of valid system values (thereby detecting exceptional conditions)

– Provides inputs and outputs for engineering analysis and simulation during system design


Constraint expressions are applied to blocks (bdd) by binding each variable to a value property (constraintparameter). A parametricdiagram can display these constraint expressions and value properties. These are similar to IBD in that it is a complementary view of the blocks (bdd).




In example above, the Figure 9.3 is a parametric diagram that represents a constraint block. It only shows the constraint properties and bindings that form the internal structure. Figure 9.4 is a parametric diagram that represents a block (non constraint). This shows the bindings between block value properties and the constraint properties.


In parametricdiagrams, the constraint property is displayed as a round-angle rectangle. The header is in this format:

<constraint name> : <type>


Constraint Parameter = variable that appears in constraint expression. (Displayed by the small square attached to the boundary on the inside). The format is the same in BDD and PAR:

<parameter name> : <type> [<multiplicity>]


Value Properties = usage of value type in the context of an owning block. In a BDD thi sis displayed as a string in the values compartment of the owning block. In a PAR, this is in a rectangle with solid boundary. The format of the name in the rectangle follows such:

<value name> : <type> [<multiplicity>] = <default value>

These values could be nested deeply within a block. In a PAR diagram, this can be displayed in one of two ways:

– Dot notation = on Figure 9.4 the orderedOrbitRadius value property

– Nesting notation = on Figure 9.4 the


Binding Connectors = special connector representing an equality relationship between two elements attached at either end, of which one of the two ends must be a constraint parameter. There is no reference of direction These connectors only appear in parametric diagrams. All the connectors in Figure 9.3 and 9.4 use binding connectors.