Image Processing Reference
In-Depth Information
controllers are programmed with the Echelon's Neuron C language, which is a derivative of ANSI
C. Other controllers such as LC are programmed with standard ANSI C. The basic element of
Neuron C is the network variable (NV), which can be propagated over the network. For instance,
SNVT_temp represents temperature in degree Celsius; SNVT stands for Standard NV Type. Network
nodes communicate with each other by exchanging NVs. Another way to communicate between
nodes is by using explicit messages. he Neuron C programs are used to schedule application events
and to react to incoming data packets (receiving NV) from the network interface. Depending on
the network media and the network transceivers, a variety of network topologies are possible with
LonWorks nodes, to include bus, ring, star, and free topology.
As the interoperability on all seven OSI layers does not guarantee interworkable products, the
LonMark organization [] has published interoperability guidelines for nodes that use the LonTalk
protocol. A number of task groups within LonMark define functional profiles (subset of all the possi-
ble protocol features) for analog input, analog output, temperature sensor, etc. he task groups focus
on various types of applications such as home/utility, HVAC, lighting, etc.
LonBuilder and NodeBuilder are development and integration tools offered by Echelon. Both tools
allow writing Neuron C programs, to compile and link them and download the final application into
the target node hardware. NodeBuilder supports debugging of one node at the time. LonBuilder,
which supports simultaneous debugging of multiple nodes, has a built-in protocol analyzer and a
network binder to create communication relationships between network nodes. he Echelon's LNS
(network operating system) provides tools that allow one to install, monitor, control, manage, and
maintain control devices, and to transparently perform these services over any IP-based network,
including the Internet.
1.6 Concluding Remarks
This chapter has presented an overview of trends for networking of embedded systems, their design,
and selected application domain-specific network technologies. The networked embedded systems
appear in a variety of application domains to mention automotive, train, aircraft, office building,
and industrial automation. With the exception of building automation, the systems discussed in this
chaptertendtobeconinedtoarelativelysmallareacoveredandlimitednumberofnodes,asincase
of an industrial process, an automobile, or a truck. In the building automation controls, the networked
embedded systems may take on truly large proportions in terms of area covered and number of nodes.
For instance, in a LonTalk network, the total number of addressable nodes in a domain can reach
; up to
domains can be addressed.
The wireless sensor/actuator networks, as well as wireless-wireline hybrid networks, have started
evolving from the concept to actual implementations, and are poised to have a major impact on
industrial, home, and building automation—at least in these application domains, for a start.
The networked embedded systems pose a multitude of challenges in their design, particularly for
safety-critical applications, deployment, and maintenance. The majority of the development envi-
ronments and tools for specific networking technologies do not have firm foundations in computer
science, software engineering models, and practices making the development process labor-intensive,
error-prone, and expensive.
References
. R. Zurawski, he industrial communication systems,
Proceedings of the IEEE
, ():-, .
. J.-D. Decotignie, P. Dallemagne, and A. El-Hoiydi, Architectures for the interconnection of wire-
less and wireline fieldbusses,
Proceedings of the th IFAC Conference on Fieldbus Systems and Their
Applications (FET )
,Nancy,France,.
