50 is an optional parameter.
A control value defi ned in SysML describes only two values, enable and disable
( Figure 4.51 ). SysML leaves it up to the modeler to extend the enumeration
type, for example, by the values suspend and resume (Figure 3.22).
FIGURE 4-49
Modeling trick for function trees.
act Confirm usage start
Confirm
usage start
FIGURE 4-50
Example for the control operator ?«continuous?».
act Show car usage data
Car movement
data
Determine car
usage data
Car movement data
Time
Car usage data
Show car
usage data
Car usage data
{stream}
End
usage
Updating
?«discrete?»
{rate1/minute}
Display
on/off
?«controlOperator?»
Enable/disable
display
?«overwrite?»
{upperbound1}
ControlValue
?«optional?»
ControlValue
{control}
261
4.8.3 Rate
4.8 The Activity Diagram
FIGURE 4-51
Example for control values.
bdd [package] UML4SysML [ControlValue]
?«enumeration?»
ControlValue
enable
disable
FIGURE 4-52
Example for using a rate.
act Determine car usage data (section)
Determine car
usage data
Updating
?«discrete?»
{rate1/minute}
Movement data
Car usage data
Time
Defi nition
A rate describes the frequency in which elements traverse an activity edge, or
flow in and out of a parameter.
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