Working with functional models

When you design a system or product, you identify all the functions it should perform and equate each to a functional block. This process creates a functional decomposition of the system or product. Often, your starting point for creating the functional model is performing a high-level analysis of the requirements. A combination of requirements and precedents typically help you define the functions.

When the functional model is complete, you can allocate functional requirements to functions, ensuring that all functional requirements are appropriately allocated.

The following example shows the functional model of a light system.

(Diagram: light system functional model example — not reproduced)

In this example, Consume minimum energy, Deliver power, and the other blocks represent generic functions. These functions typically cannot or should not be represented by items in the product structure.

After you create the functional blocks, you link the functional model blocks with functional connections. You allocate functional requirements to functions, ensuring all functional requirements are allocated.

You then create the logical model and connect the elements with logical connections, pins, and ports. The following example shows the logical model of the light system. The logical blocks are implemented by equivalent physical parts in the physical structure. Each functional connection has interfaces (or ports), each of which may be an input, an output, or bidirectional.

(Diagram: light system logical model example — not reproduced)