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

41-12 Industrial Communication Systems
development possible but fails for multi-vendor LonWorks systems. Because of this restriction, only
the before-mentioned multi-vendor system integration tools are regarded here.
LNS-based system integration tools support two different network installation scenarios. In
the engineered mode, the entire network is designed without commissioning any devices until the
design is complete, and in the ad-hoc mode, all network configuration information is immediately
loaded into the devices. Thus, the engineered mode is the only way to design a network without
having access to the physical devices, whereas the ad-hoc mode is only possible for onsite network
installations.
With the LNS database as backend, the different system integration tools offer specific user interfaces.
LonMaker follows a graphical block-oriented design that allows a drag-and-drop–based placement and
connection of functional blocks and devices. In contrast, NL220, Alex TE, and Network Integrator are
tree-view oriented and do not support graphical views of the logical network.
Despite different user interface representations, all mentioned tools widely support the same design
tasks. Typically, the proceeding starts with the definition of a domain and one or more subnets and
channels. Devices can be added to a channel in the next step. This involves the creation and instantiation
of LNS device templates for each device type based on their XIF files or per download of the devices’
self-description (in ad-hoc mode only). The device templates contain essential information for the LNS
database and system integration tools. They describe various device hardware criteria like transceiver
or processor type, communication settings, functional blocks, their interfaces, network variables, and
configuration properties.
Once a device has been added, its functional blocks can be used and connected via bindings with
other blocks. Functional blocks may need to be parameterized, which is possible either by directly setting
the configuration properties or via comfortable LNS plugins, delivered by the device manufacturers.
Furthermore, various other settings can be made, for example, adding routers and gateways or
setting up authentication.
Among all LNS-based system integration tools, NL Facilities deserves an exceptional position since
it mechanizes many repeated actions. The key elements are semiautomatic approaches based on solution
libraries for reuse. NL Facilities provides a graphical representation of the floor plan, where the
user just has to place devices into rooms and define interrelationships among devices. It fully hides the
technology from the user and thus makes it appropriate also for nonprofessionals. However, this procedure
works fine only for networks with many identical, predefined devices, whereas a high variability
restricts its applicability.
41.7 automatic Design Approaches
More advanced than NL Facilities are the automated design approaches from the AUTEG project [18].
The automatic design tools developed there are able to cope with the variety of all market available
devices from all manufacturers by using semantic device descriptions [19]. Industry spanning, multivendor
LonWorks-based building automation systems are generated automatically [20,21]. The design
process starts with a formal requirement specification, where functional and nonfunctional requirements
for the building automation system are gathered. All subsequent design tasks are done automatically,
including the generation of functional schematics for all rooms [22], the selection of appropriate
devices fulfilling the requirements, the evaluation of interoperability, the definition of bindings, parameterization,
and layout of the physical network. Evolutionary algorithms are used to obtain optimized
LonWorks systems according to multi-objectives such as costs, correctness, completeness, and interoperability
[23].
Also, quality-oriented aspects are incorporated here. By forecasting the resulting network load
already at the early design phase, bottlenecks and network overloads can be identified before the system
is built [24,25]. Modifications of the physical network and the parameterization are done to avoid these
problems.
© 2011 by Taylor and Francis Group, LLC