Dedicated Systems
e-Magazine Q1 - 2003
| New articles
will be added to this Q1 e-Magazine until April 30 2003. Don't hesitate
to come back.
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| EDITORIAL |
Towards a new era
in publishing Dedicated Systems Magazine
Martin explains his new approach in publishing:
it is a concept bringing together paper, web and CD publishing.
By Martin Timmerman, Chief-Editor of Dedicated
Systems Magazine
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| SYSTEMS |
High availability systems: the ever-growing
HA stack.
As High Availability systems have
evolved, so has the equipment manufacturers' approach to product development.
With the development of more highly reliable and fault tolerant architectures,
equipment developers, whether in the communications, mil/aero or industrial
sectors, now see they can offer their customers HA architectures that
reduce operational expenditures and revenue loss due to service interruptions.
By building always-on applications around these HA architectures,
end customers are noticing significant reductions in total cost of
ownership. Under the shadow of the current economy, minimizing total
cost of ownership is a theme that resonates throughout the industry.
Traditionally, levels of HA were calculated based on the Mean Time
Between Interruptions data collected from the hardware components
in a system. This determined a number of "nines," or the percentage
of time per year that they system remains functional. Now, HA can
be defined by an integral suite of redundant hardware components and
specialized layers of software components, commonly known as the "HA
Stack.". By Tony Romero and Sean O'Brien,
sr. product manager and software engineering manager.
Performance Technologies.
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| Embedded OS |
FSMLabs RTLinux PSDD: Hard real-time with memory protection.
RTLinux was designed to run at the
highest possible speed with the lowest possible overhead. For most
of its existence as a product, RTLinux did not offer memory protection
for threads on the grounds that the overhead in terms of context switches
and requests for system services was unacceptable. The rapid increase
in speed and cache size of modern microprocessors, however, and requirements
of customers in aerospace and manufacturing test forced a re-evaluation.
After a significant design effort including several false starts,
RTLinux Process Space Development Domain (PSDD) was released in 2001.
The challenges were to make the system fit cleanly within the RTLinux
POSIX threads API, to minimize additional overhead, to prevent the
new system from interfering at all with the existing unprotected thread
system, and to produce a reliable and maintainable design.
PSDD
was initially aimed at FSMLabs customers in aerospace manufacturing
test. Several of these customers use test frameworks that mix-and-match
software simulations and control programs for physical components.
Since simulation codes are often very complex and come from multiple
suppliers, it is necessary to ensure that coding errors in any simulation
component cannot result in undetected changes to data or code of other
software - especially software controlling large and powerful physical
components. Memory protection is necessary but not in itself a complete
solution. PSDD tools include methods for incorporating Fortran and
C++ simulations in control loops, a secondary frame or slot
scheduler, full support for SMP, and protection against scheduling
overruns.
By Victor
Yodaiken & Michael Barabanov
FSMLabs
Inc.
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| TOOLS |
ProcessLogix
- SCADA for Process Productions
In present time not any SCADA-system represented in the market of
IT-technologies, can't "to be
praised" by dynamic self-configuring of System. In the article
is described the modern SCADA-system of the leading manufacturer of
means and systems for automation of technological processes of company
Honeywell - ProcessLogix Release 300.1. As was writed in the previous
article, ProcessLogix is a hybrid of hardware-software of the world-leaders
in the field of
automation - Honeywell and Rockwell Automation. ProcessLogix has a
high degree of reserved (controllers, servers, network low and high
level), high degree of fault tolerance, selfdiagnosis open
DataBase, client-server architecture. One from distinctive features
ProcessLogix from SCADA-systems, represented in the world market,
is dynamic self-configuration. In real-time configuring all System,
in particulary:
*Trends - set of any parameters in a trend (up to 8 parameters),
ranging of map, setup interval of registration.
*Database of parameters - for registration in
trends (for example, the parameter was circumscribed for registration
with an interval 1 minute - Standard History and it is necessary for
registering with an interval per 5 seconds.
*Reports - select the necessary period, level and reports is selected.
*Displays - in the editor displays HMI is draw the mnemonic scheme
and saved in the necessary directory. This display automatically occurs
in the list of displays HMI. *Events - nothing to configure! Everything,
that hits in alarm and message, is registered automatically. Operations
of an operator - modification settings and coefficients of the PID-instruction,
modification of the user, emergency condition of a system (absence
of connection with controllers, shutdown and reboot of servers) -
all is registered by system automatically!
This some properties of a system, which gives advantage of use in
process productions, such as oil processing. Don't to compile the
project for to add mnemonic scheme or to change a configuration of
a trend or to add new trend, to change parameters of automatic formed
of the report or to change of set-up of a System.
By Roman
Krutskikh, Control System Engineer, Bachelor of Engineering and
Technologies,
JSC "NizhnevartovskASUneft"
ProcessLogix
Inc.
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| CASES |
A flow control approach
and interleaving method for Real-Time application in high-speed
network.
Nowadays, many multimedia and real time applications are more and
more greedy in
term of bandwidth and require a technology which meets this need.
In this respect, the
Asynchronous Transfer Mode ATM is widely used as a transfer technique
for such applications [Djemal 2000]. It consists of a connected
oriented network, where data is carried in a short fixed-length
packet of 53 octets, called cell. This technology was initially
designed to permit simultaneous carrying of various services all
supported equivalently without any knowledge of its cell content,
i.e. without discriminating some cells against others. Among all
the services, variable bit rate in multimedia environment and especially
digital video communication should contribute as an important fraction
of the overall traffic. Due to the nature of the compression technique,
the MPEG-2 sequence is inherently variable asynchronous, stochastic
and non stationary. In order to provide an agreed quality of service,
the network interface must be able to ensure minimal congestion
conditions and to optimize the bandwidth allocation according to
the need of the real time constraints.
On the other hand, the residential audio visual applications such
as TV broadcasting, and Video On
Demand (VOD) will works on the basis of high speed network techniques.
These video applications will widely use the motion picture expert
group (MPEG) compression standards to save network resources. These
video compression algorithms are mostly based on efficient DCT and
block oriented techniques DCT, H.261 (video codec for audiovisual
services at Px64 Kbps), ISO JPEG (Joint Picture Expert Group) and
ISO MPEG-1 (Moving Picture Expert Group) [Schaphorst 96]. Unfortunately,
they have been designed to support specific services and applications,
and they can not interoperate or run without restriction over based
ATM network. For instance, the H.261 scheme was initially designed
to operate over a pecific digital networks like Narrowband-ISDN
with a low rate about Px64Kbit/s to carry on teleconferencing applications
where motion is naturally more limited. In the same way, JPEG algorithm
only emphasizes images and do not apply any inter-coding algorithms
to take into account temporal redundancy of moving picture sequences.
For this application, processing delay was not a major concern for
both H.261 and JPEG-1 [ISO/IEC DIS 2-1172 93].
Until now, few works have considered to allow a new higher quality
video coding over the B-ISDN network related to the application
which is a delay sensitive [Mehaoua 96,Seckin 2000]. Consequently,
an important effort should be devoted to inter-operate a heterogeneous
standard like MPEG-2 [ISO/IEC 13818-2 96] and ATM network to benefit
from this environment for real time applications with agreed quality
of service [Frater 99]. In fact, the transport of Picture compressed
video applications over ATM network introduces several issues that
must be considered in order to ensure a high end-to-end quality.
This includes the choice of adaptation layer packets for the network
side, the traffic management mechanism, the cell mapping algorithm,
and Interleaving and recovery schemes.
By
By Belgacem Bouallegue, Ridha Djemal, Hattab Guesmi, Rached Tourki from
Laboratoire Microélectronique (Tunisia) and Jean -Philippe Diguet from
Laboratoire Lester (France).
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