Overview of ValueTypes and Units

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Tutorial
TRAIL: SysML: Simple model of an air conditioner with a refrigerant cycle and StateMachine driven by Activities in MagicDraw/Cameo
Section
UML keywords
InformationFlow
InformationFlow::conveyed
Signal
SysML keywords
ValueType
ValueType::unit
ItemFlow
ItemFlow::itemProperty
Block
Keywords
Slide kind
SysML Package Diagram
This Package Diagram shows an overview of some of the ValueTypes and Units used in the system:
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Additional Dependency relationships between ValueTypes and their Units on some SysML diagrams on this site are for educational illustration only (you don't need them in your own SysML models).

You can use ValueTypes not only to type value properties of Blocks, but also a conveyed Classifiers on SysML ItemFlows. However, sometimes it is better to choose a Block to encapsulate something that flows (as we'll see also in later slides):

Webel Best Practice: SysML: Whether you use a Block, ValueType, or Signal to represent something that flows (and can be applied to an ItemFlow) depends on what you want to achieve. If you want to indicate something structured with value properties with Units use a Block.

A Signal (packaged elsewhere) has been chosen to represent a digital TemperatureReading to distinguish it from physical quantities (mostly represented by ValueTypes), which is fine for InformationFlow-style ItemFlows with a conveyed Classifier, but not as well suited for finer-grained ItemFlows with an itemProperty:

SysML: Flows: If you use a Signal to type the itemProperty of an ItemFlow on a Connector, care must be take in how you create the Property or you might get an unwanted signal Reception on the owning context Block.
Up next
Overview of flowing quantities and Port types with flows
Notes
[CAVEAT, MODELLING]{INFORMATIVE} Additional Dependency relationships between ValueTypes and their Units on some SysML diagrams on this site are for educational illustration only (you don't need them in your own SysML models).
[MODELLING, OPTION, TIP]{INFORMATIVE} SysML: Whether you use a Block, ValueType, or Signal to represent something that flows (and can be applied to an ItemFlow) depends on what you want to achieve. If you want to indicate something structured with value properties with Units use a Block.
[MODELLING, OPTION, TIP]{INFORMATIVE} SysML: Flows: If you use a Signal to type the itemProperty of an ItemFlow on a Connector, care must be take in how you create the Property or you might get an unwanted signal Reception on the owning context Block.
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