wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

5-4 Industrial Communication Systems
5.2 application of Profiles
This section describes some examples for functional profiles as they are covered by different standards.
5.2.1 Function Blocks of IEC 61499
Distributed systems used for automation have been standardized in the IEC 61499 standard. This standard
describes an architecture for communication networks and processes that can be used for designing
system applications. Interoperability is a central concept that has to be achieved. The core component
in IEC 61499 is a Function Block, which is a module that has a certain function and provides the output
of this function based on its input to other components using an interface. This interface consists of
both Event Inputs/Outputs (I/Os) and Data I/Os. Internally, the Function Block executes an algorithm,
which processes input data and produces output data, but this algorithms is not visible from the outside.
Output data can be transferred to other Function Blocks and become input data for the other block.
Basic Function Blocks are the most elementary blocks; Composite Function Blocks can be composed
of multiple Basic Function Blocks. Using these Function Blocks, it is possible to design a system with a
high degree of modularity. IEC 61499 is intended to describe a generic modelling approach for control
applications that are distributed over multiple components and thus have to be built in a modular way.
Another aspect of modularity is the fact that information flow and control flow are separated by means
of Event I/O and Data I/O.
5.2.2 Functional Profiles in LON
LON was developed for building automation. It makes it possible to distribute the automation functions
in, for example, light control, sunblind control, heating, ventilation, and air conditioning all over the
buildings [2].
Figure 5.3 shows a simple example for a light control. It is possible to switch a lamp on and off from
two different switches. Both sensors (i.e., the switches) and the actuator have their own microcomputer
(Neuron-Chip). The function for the light control is distributed on these three microcomputers.
µC
Switch S2
Lamp actuator E1
µC
µC
Switch S1
LON
FIGURE 5.3
Example for a simple LON network.
© 2011 by Taylor and Francis Group, LLC