Example¶

The following is a partial example of an electric coffee maker.

A customer wants to make a cup of hot coffee. The team’s concept is an electric coffee maker that uses a drip method. Figure 1 shows the flow diagram of the system architecture. The team chose not to design an insulated coffee cup (S700).

Figure 1 System Architecture Flow Diagram

The following tables summarize interactions among the subsystems.

Table 1. UI (User Interface) Subsystem Interface (S100)

No.	Source Subsystem (from) and Inputs (Interface)	Destination Subsystem (to) and Outputs (Interface)	Notes
1	1. A user selects the amount of coffee to be made.
2	2. A user selects Start.		Pre-Condition: The amount of coffee to be made must be selected.
3		7. Send the amount of coffee to be made to the S300 Controller.
4		8. Send the start command to the S300 Controller.

Table 2. Power Supply Subsystem Interface (S200)

No.	Source Subsystem (from) and Inputs (Interface)	Destination Subsystem (to) and Outputs (Interface)	Notes
1	3. Electricity from a wall power outlet.		110V AC
2		9. Power for the controller (S300), the water heater (S400), and the dripper pump (S500).	low voltage DC

Table 3. Controller Subsystem Interface (S300)

No.	Source Subsystem (from) and Inputs (Interface)	Destination Subsystem (to) and Outputs (Interface)	Notes
1	7. The amount of coffee to be made from the S100 User Interface subsystem.		110V AC
2	8. The start command from the S100 User Interface subsystem.
3	9. Power from the S200 Power Supply.
4		10. Send power for heating water to the S400 Heater & Tank subsystem.
5	11. Water temperature from the S400 Heater & Tank subsystem.
6		12. Power for running a pump to the S500 Pump subsystem.	The pump must not be started when the water is cold.