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The step after the functional architecture definition in the system engineering process is the physical architecture definition. Indeed, a system is composed by several components, linked each to others. In order to model components and links, we will find in this step new arKItect object types, component and physical interface, and new arKItect link type, physical relation. We will have two levels of physical interfaces, external and internal. Indeed, there are, on the one hand, physical relations between the system and its environment, and on the other hand, physical relations in the system, between its components. Physical relations we are talking about are modelling the flows we defined in the functional architecture but with a physical approach. To illustrate, in the functional architecture, we defined a flow called "220 V supply" between the system and an enabling system. This flow will be model in the physical architecture by a physical relation supported by a physical interface (as an electrical cable for example).

We will now see how to define the physical architecture. As we are progressing in the system engineering process, we change our current working view and will use the view  "4.0. Define physical architecture".


Create components and physical relations

Create external physical relations

Interface between Enabling systems and system

In the functional architecture, we defined functional relations between enabling systems and system. We will now model this flows using physical relations. Arriving in the working view "4.0. Define physical architecture", we find the system and enabling systems. We will place physical interfaces between them and draw physical relations. Let's consider an example. Between the enabling system "Office" and our system "LapTop", we defined in the functional architecture a flow called "220 V Electricity". So there is a physical relation between these two objects. Things to do to model it are :


Names given to physical relations are not important, this links are drawn only to link objects graphically. Furthermore, physical relations are bidirectional flows, meaning they have neither producer nor consumer.

First step is to create the physical interface "Electrical cable". Using the palette, drag-and-drop an object of type physical interface in the diagram and choose the name "Electrical cable".


We will now have to link the physical interfaces with concerned objects drawing physical relations. An object physically linked with an other are, as we said, linked by physical interfaces (cables, ducts...). Sometimes, the object connector is really important so we have to model this connector. In arKItect, we use the type link area to model such connectors. In our example, connectors will be:

  • "Electrical wall plug" for the Office side
  • "Supplying port" for the LapTop side

To create those link areas, you can enter the parent object ("Office" and "LapTop") and create link areas there, or drag-and-drop from the palette a link area object directly on it. We now create a link area in "Office" we call "Electrical wall plug" and an other in our system "Laptop" we call "Supplying port".

We are now able to show the physical connection between the "LapTop" and the "Office" supported by an "Electrical cable" connected between the Office "Electrical wall plug" and the LapTop "Supplying port". On this purpose, we will draw physical relations between the physical interface "Electrical cable" and link areas we created. To draw such links, use the link button
and select the two objects two link, here the link areas. Using the expand feature, you are able to see them in them parents and so to draw the link.


As you probably noticed, we are not talking about producers and consumers. Physical relations are a special kind a flows we call bidirectional. That means the flow is going in both direction between objects. It's pertinent in this case because we can say that the LapTop is physically linked to the Office as we can say the Office is physically linked to the LapTop.



Interface between Enabling systems

As we modeled functional relations between several external elements, we will model the physical relations between the same elements. In our example, we draw a flow "220 V supply" between the "Office" and the "LapTop". We also defined a flow "220 V" between "Office" and "Screen". So we will also model a physical interface we will call "Electrical cable 2" between those two enabling systems. As for the precedent we model, we will link it to link areas we create in connected elements. So we will create a link area called "Electrical wall plug 2" in the enabling system "Office" and another called "Screen supplying port" in the enabling system "Screen". We finally create physical relations flows between each of this link areas and the physical interface "Electrical cable 2".


Create components and internal physical relations.

Create components

We will now define components of our system "LapTop". components are modeling the components of the system. In our example, we will define two components, "Mainboard" and "Network card". To create components, go in the system (double-clicking on it) and use the palette to drag and drop an new component object. Give it the wanted name. The system now contains all created link areas ("Supplying port" in our example) and all created components "Mainboard" and "Network card" in our case.


Create physical relations between components and external elements

Some internal components (components) will be connected directly with external elements. To illustrate, we will create an ethernet relation between the "Rooter" and the "Network card". On this purpose, we will create a physical interface out of the system called "Ethernet cable". Then, we create two link areas, "Rooter ethernet port" in the "Rooter" and "LapTop ethernet port" in the component "Network card". We finally draw physical relations between the two link areas and the created physical interface.


Create internal physical relations

We also have to model the internal physical relations. Using same way, we create physical interfaces (inside the system this time); link areas in concerned components and connect link areas with the physical interface.

In our example, we will connect the "Network card" and the "Mainboard". We will use a "PCI interface" to connect them, with a "Female PCI slot" link area in the "Mainboard" and a "Male PCI slot" in the "Network card".



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