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Chapter 3. Concept 30

The device manager node connects HA protocols with a set of data, which contains the most

important information about the device. The data is stored in a XML database. Special lookup

and control functions allow the HA system to be managed by changing entries in the database.

Thus, the device manager allows device handling without knowledge of their protocol codes and

types (HE or IT) as well as keeping track of the current state of each device.

The visualization node oﬀers visualization functions for graphical control over the HA system.

In addition, it provides a namespace service, which allows devices to be assigned to diﬀerent

namespaces. These namespaces can represent diﬀerent locations, such as buildings, ﬂoors and

rooms. As a result, devices can be divided in groups depending on their location. This is useful

for larger networks, as information becomes more readable and local devices can be ﬁltered.

The visualization node oﬀers abstracted device and location information, but nevertheless, it can

sometimes be useful to access other information, like protocol data, too. The higher software

layers do not hide all previous layers, so each nodes can always be accessed by their ROS topics.

Since ROS topics conceal receiver and sender, the internal structure is not directly visible from

the outside; the user will rather see a bunch of diﬀerent topics and can decide which degree of

abstraction he wants to use.

3.4. Device Management and Abstraction

The communication chain shown in Figure 3.1 converts raw binary data to a human readable

string format with namespaces, for example "0x000AA8" → "dormitory/table_light". It aims to:

• Create human readable topics and data structures to allow an easy and intuitive use of the

data.

• Hide information such as protocol timings, addresses of devices, etc. to relieve the IE from

unnecessary data.

• Accelerate the development of new software, since little to no foreknowledge is required on

communication details of HA systems.

The abstraction is mainly performed by the software, which consist of three parts. Figure 3.4

shows the diﬀerent abstraction stages for an example, where a remote control turns a light on.

The gateway receives the on-code "IT AA8A" and sends it to the gateway driver, where protocol

type and data are separated. The device manager then compares the data with its database and if

a matching entry exists, it delivers a detailed data structure to the visualization node. There it is

compared to a namespace database and if a match occurs, the full namespace with device name

and new device state is provided. Note, that the database of the visualization node contains no

device information. It consists of a list of namespaces with a list of device names. This simpliﬁes

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