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Value types and Verb definitions

Value types are used to define the types (unit) of parameters and variables in the component and block definitions. Value types are defined in both ESL and SysML, but they differ in their representation.

ESL

The value types are defined using the define type statement. The variables may represent flows from the interaction basis, such as electrical energy and information, or properties (attributes) of components, such as length, weight, cost and reliability.

The verb definitions are defined using the define verb statement, which is used to define the actions that can be performed on the parameters and variables. The possible actions are restricted by these definitions.

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define type
  mechanical-energy-flow is a real with unit Nm
  electrical-energy-flow is a real with unit W
  liquid-material-flow is a real with unit L/s
  energy-potential is a real with unit Wh
  control-signal is a boolean
  distance is a real with unit m
  spatial-measure is a distance of at least 0.0 [m]
  efficiency is a real  of at least 0.0 and at most 1.0


define verb
  provide to
  convert into
  send to

SysML

The value types are defined in SysML using a DataType block. The DataType block allows for the definition of custom data types, which can be linked to the parameters and variables in the block definitions. Similar to the block definitions, the DataType block can be decomposed into subtypes. The subtypes are linked using the Generalization relationship, meaning that the subtypes are "a type of" the parent block.

SysML does not have a verb definition, but the actions are defined in the Activity Diagrams (without any specific syntax). These will be explained in Activity diagram.

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