Up to this point, we've studied relatively simple devices, each fitting neatly into a physical device. But often, you can add value to your physical device, if you divide it into multiple logical devices. A simple example may be our sensor. It senses two different things: ambient light and motion. These two things are independent of each other and could be modeled as individual sensors logically. But running them on different Raspberry Pi would be more expensive and would only make sense if the actual sensors were separated by some distance. For that reason, it is more cost efficient to implement them into one single unit. They share the same Raspberry Pi, operating system, and network connection.
Dividing a device into multiple logical devices permits you to do things you normally would not do with a single device: you can manage and operate them...