Image Processing Reference
In-Depth Information
Continuous process manufacturing unit
predominantly analog
Discrete manufacturing unit predominantly
discrete
Device count per unit
1,000
Installation cost/device cost
Unit physical size (m)
1,000
10
100
1
100
10
1,000
Units per plant
Field device cost ($)
100
100
10
1
10
1
0.1
Device density (in unit)
Time: slow (s)
0.01
0.1
1
10
100
0.001
0.01
0.1
1
10
10
1
1
0.1
0.1
0.01
Time: control loop (s)
0.1
Devices per plant
10,000
1
10
0.01
10
1,000
Time: fast/subunit (s)
Production cycle length (h)
0.001
100
Unit startup time (min)
FIGURE .
Process attributes.
27.3.1 Diverse Requirements
As highlighted in the previous section, the target industry and application can pose quite differing
requirements on the choice of communication technology, as well as impose quite rigid restric-
tions on the embedded design. The requirements can be grouped into nonfunctional requirements
that stem primarily from the target environment, and functional requirements given by the target
application.
The environmental conditions of the target industry have a major impact on the boundary condi-
tions of the embedded design and choice of communication technology. For example, factors such
as heat, moisture, and vibration influence the packaging of the device, which in turn imposes addi-
tional requirements on the power consumption, as well as restrictions on the antenna design and
power supply solution. If the device shall be used in hazardous environments, special consideration
must be taken throughout the design process.
The application requirements more or less dictate the duty cycle of the WSN, which has a huge
impact on choice of technology and a direct influence on the low-power design and required response
time. In addition to the autonomous operation of the device, the human-machine interaction can
pose additional requirements on external interfaces that influence both the communication solution
as well as the packaging of the device.
27.3.2 Choosing Communication Technology
A clear view of the requirements helps eliminate obvious communication solutions. However, it is
common that one needs to make a trade-off in the end to be able to address the main requirements
that are driving the application.
