TABLE OF CONTENTS This chapter addresses modeling the structure of systems in terms of their hierarchy and interconnection. It describes blocks the principle structural construct and the two types of diagrams used to represent structure the block definition diagram and the internal block diagram.
The block is the modular unit of structure in SysML that is used to define a type of system, system component, or item that flows through the system, as well as conceptual entities or logical abstractions. The block describes a set of uniquely identifiable instances that share the block's definition.
The block definition diagram is used to define block characteristics in terms of their structural and behavioral features, and the relationships between the blocks such as their hierarchical relationship. The internal block diagram is used to describe the internal structure of a block in terms of how its parts are interconnected.
Properties are the primary structural feature of blocks. Part properties describe the decomposition hierarchy of a block and provide a critical mechanism to define a part in the context of its whole. Value properties describe quantifiable physical, performance, and other characteristics of a block such as its weight or speed. Value properties are defined by value types that describe the valid range of values, along with its dimension (e.g., length) and its units (e.g., feet or meters). Value properties may be related using parametric constraints as discussed in Chapter 7.
Ports are structural features that describe the points at which a block interacts with other blocks and are used...
