Remote Laboratories – Multiple Task Server
Lukáš Pawera
Petr Sládek
Department of Physics
Faculty of Education, Masaryk University
Poříčí 7, 603 00 Brno, Czech Republic
pawera@mail.muni.cz
Department of Physics, Department of Didactic Technology
Faculty of Education, Masaryk University
Poříčí 7, 603 00 Brno, Czech Republic
sladek@ped.muni.cz
Abstract - Remote laboratories, i.e., laboratory accessed via the
PC and the Internet, represent one of the unusual opportunities
of today's applications of Internet and computer technology.
Moreover, the rapid development of the computerized “remote”
activities in daily life requires training of the appropriate skills.
The goal of remote laboratories is not to replace the classic
experiment, but to provide an existing physical experiment to
someone who has no, for whatever reason, the possibility of
making a classic experiment in his own laboratory. The
important thing is that remote laboratory enable access to real
experiments and does not represent simulation, or modeled
physical phenomenon, or recording. In our paper we present new
possibility of the interface between several classic experiments
and one server created based on system ISES and software for
remote laboratory ISES Web Control.
Keywords - remote laboratory; web; multiple task
I.
INTRODUCTION
Today's computer technology offers great possibilities and
that is why it has built a permanent position in the education.
Moreover, its role is constantly expanding and reinforcing.
Remote laboratories, i.e., laboratory which access is mediated
via the PC and the Internet, represent one of the unusual
opportunities of today's applications of Internet and computer
technology. Their goal is not to replace the classic experiment,
but to provide an existing physical experiment to someone who
has no, for whatever reason, the possibility of making a classic
experiment in his own laboratory. The important thing is that
remote laboratory enable access to real experiments and does
not represent simulation, or modeled physical phenomenon, or
recording. Control of the experiment, measurement and data
recording are done remotely from our web page
http://ises.tym.cz/.
However, applications for these remote activities were
developed in a specialized server – client application when
necessary software is needed to operate measuring equipment
and to publish results on the Internet. Such software needs to
be installed on the remote computer and may need a license.
Therefore, students’ remote laboratories are very rare.
As a counterweight to the situation described above we
offer the possibility to use an ordinary web browser instead
specialized software on the client computer.
These laboratories certainly can not replace a classic
experiment, but in most cases can serve as a suitable alternative
[1].
II.
SYSTEM ISES AND ISES WEB CONTROL
SOFTWARE KIT
The system ISES [2] contain the computer interface card
PCI ADDA convertor-12 bits, a universal control board and a
set of sensors. The system offers the possibility of
simultaneous measuring and data displaying for 8 input
channels and process control via 2 analogue and 2 binary
output channels. The analogue outputs channels work as
programmable voltage sources. The ISES system is supplied
with a set of sensors - ammeter, voltmeter, thermometer,
simple position sensor, capacity-meter, ohmmeter, force meter,
anemometer, microphone, sonar, light gate, pH-meter,
conductivity meter, heart frequency meter, current booster,
repro, loudspeaker, relay, electromagnet valve for liquids and
others. The ISES modules are easily interchangeable, the
computer, provided with the automatic calibration,
automatically senses their presence and adjusted range.
The operation of remote laboratories appears to be a
complicated task. To the contrary the creation of websites has
become a routine matter. The ISES WEB Control software kit
[2] is software for supporting remote measurements and control
making it possible also for beginning WEB site authors to
integrate in their pages also elements for the support of remote
experiments. It includes 3 main components of Web server [2],
ImageServer [2] has the task transmit image from Webcam,
MeasureServer [2] is responsible for the management of the
hardware. These three components are further complemented
by a set of Java applets. The applets contain a lot of input
parameters so that also an advanced user may adapt such an
applet to his needs. Web interface for each experiment is
created by inserting an applet into normal html web pages and
their configurations. This creates a whole kit, which can be
widely modified and thus create even complex measuring
assembly controlled through a web interface. To control
experiments you need just a computer connected to the
Internet, web browser and installed Java support. When you
enter a Web address into browser, it loads a web page interface
with experiment, from which the user can measure and control
processes and where he can survey the experiment via the
webcam, when it is required by the nature of experiment. All
978-1-4577-1746-8/11/$26.00 ©2011 IEEE
21–23 September 2011, Piešťany, Slovakia
14th International Conference on Interactive Collaborative Learning (ICL2011) ̶ 11th International Conference Virtual University (vu'11)
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measurement data can be saved and exported for further
processing by simply clicking on the appropriate icon.
The basic prepared applets for remote laboratory allow
functions as:
•
display actual value of appropriate input channel
•
graphics dependency of variable on time
•
graph of interdependency of two or more variable
•
saving and loading of measured data
•
control of output cannel by scroll bar
•
generating of sinusoidal or another output signal
III.
NEW APPROACH
The purpose of this study is to build a set of remote
experiments that can be controlled from a remote computer via
ordinary web browser and create a user-friendly web
environment that enables remote control of these tasks. In
addition, the project aims to prepare the students how to
incorporate computer activities in daily life.
Instead of one complicated experiment design we chose
several simpler thematically linked experiments forming one
larger unit. Design of experiments must fulfill several
important aspects. The control must be simple and intuitive; the
experiment has to work repeatedly and must be operational
without external intervention. Therefore, not every experiment
is suitable to be implemented as a remote control experiment.
This is another reason why we chose experiments with
semiconductors devices as pilot theme. The proposed
measuring kit includes minimum mechanical moving parts, and
thus it increases the reliability of the experiments. Remote
laboratory is accessible through a Web interface. User can from
his computer keyboard directly control the existing real
experiment and watch it via webcam. The experiments will
also include the relevant instructions to the theory of individual
experiments.
We chose an innovative approach in developing a remote
laboratory, where multiple experiments based on the widely
spread ISES computer assisted system are driven by only one
server. The amount of analogue inputs on the ADDA card
directly offered the possibility to use one server for multiple
experiments. This idea has not yet been practically
implemented.
ADDA PCI1202 card contains 32 SE or 16 dif. analog
inputs, 2 analog outputs, 16 digital inputs and outputs.
Sampling frequency is 110KS./s. These are the parameters that
are interesting in terms of usability. ISES modules are
connecting via the Control board. There is a physically
limitation of number of input analogue measuring channels up
to 4 input modules of the system ISES, and another 4 analog
inputs with a range of 0-5V.
One of an objective is better usability of an ADDA card.
Hence, there is no other option than exclude the Control Board
from the path of signal and make available additional channels
on the output connector of the measuring card. For added
versatility, the input channels are configured to differential
mode (ISES default is single ended). Range 0-5 V remained the
same. This intervention has resulted in the possibility of
simultaneous measurement of 16 input channels; up from
previous 4 ISES modules + 4 SE 0-5V inputs. Using the
measuring modules in this new configuration without a Control
board is still possible. But it could be also use modules of other
school system like Leybold or Vernier. But most interesting is
the use of proper measurement converters designed specifically
for a particular experiment.
Existing remote experiments built on the platform ISES
Web Control always use one remote server for one experiment
with a single version of the web interface. With the new
possibility of input channels, we offer the ability to run
multiple experiments simultaneously on a single server. If it is
properly chose configuration of the experiment is also possible
to use multiple versions of a web interface for each experiment.
Each modified version of web interface could be focused on
other issues. The experiment will become easier to use.
The theme of new online experiments with semiconductor
devices was chosen for several reasons. First, there is an effort
to move closer with a contemporary theme to large amount of
students, who could benefit from experiments in their study.
Second, an acquisition of a remote laboratory is not a cheap, so
there is an intention to create a set of experiments at the lowest
possible cost. Instead of one complicated experiment design we
chose several simpler thematically linked experiments forming
one larger unit. Design of experiments must fulfill several
important aspects. The control must be simple and intuitive; the
experiment has to work repeatedly and must be operational
without external intervention. Therefore, not every experiment
is suitable to be implemented as a remote control experiment.
This is another reason why we chose experiments with
semiconductors devices as pilot theme. The new,
semiconductor devices oriented set of experiments with
enables to measure basic characteristics of some semiconductor
devices.
The proposed measuring kit includes minimum mechanical
moving parts, and thus it increases the reliability of the
experiments. Remote laboratory is accessible through a Web
interface. User can from his computer keyboard directly
control the existing real experiment and watch via webcam.
The experiments will also include the relevant instructions to
the theory of individual experiments.
The limitation of this solution is that only one user can
carry out experiments at the same time.
IV.
TECHNICAL DESCRIPTION
ADDA card used for new remote lab with semiconductor
devices is PCI1202 (ISES Pro PCI). Card contains analog
inputs with 12 bit resolution. It is set to differential mode, so it
is able to connect 16 analog signal channels with 0-5V range,
sampling rate is 110kS./s. The function of the Control Panel,
i.e. the identification of laboratory measurement modules
through the WIN ISES software is not anyway supported by
the software for remote experiments ISES Web Control. To
measure the characteristics of semiconductor devices we use
978-1-4577-1746-8/11/$26.00 ©2011 IEEE
21–23 September 2011, Piešťany, Slovakia
14th International Conference on Interactive Collaborative Learning (ICL2011) ̶ 11th International Conference Virtual University (vu'11)
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voltmeter and ammeter. We could use ISES modules - ISES
voltmeter or ammeter has optional 4 ranges, but they cannot be
remotely switched, only manually, what is unusable for remote
experiments. It is need power supply - two analog outputs
could be used after amplify as a remote power supply or
remote generator of analog signal. For switching some parts in
measuring circuit is used relay controlled from digital output
from PCI1202 card.
Voltmeter and ammeter with remote setting of range we
could easy make from high accuracy instrumentation amplifier,
the AD620 that requires only one external resistor to set gains
of 1 to 10,000. To remote set relevant resistor we use the
digital outputs of ADDA card. Digital signal from the card via
relay can connect resistor to amplifier to get required gain. To
measure voltage of both polarities it is need to set offset to 2.5
Volts via reference voltage. So, with zero potential on
measuring terminal is 2.5 Volts on the output of amplifier
connected to differential inputs of A/D. It is because the range
of AD converter is set 0 - 5V that is why we must adjust
signals to be able to measure negative voltage on the same
range with positive voltage. To measure higher voltage then is
range of AD converter we can use active or passive voltage
divider. To measuring current in circuit it is use the measuring
voltage drop on the known resistor, whose value can by
changed by digital output and the relay.
Remote measuring circuit to measure parameters of
semiconductor devices is the same as in classical laboratory,
but reading variables and controlling of parameters in the
circuit is via a web interface. From the above, we can use in
our laboratory up to 16 voltmeters or ammeters. It is
impossible to use all of them in one circuit, so we make a
several circuits to use the measuring card more effectively then
in remote experiment created ever before. Each experiment has
own web interface, but each measuring circuit can have more
web interfaces. For example, the simple circuit with diode can
be used for measuring I-V characteristic of different diodes, but
the same circuit can be used in other web interface for
demonstrate of diode rectifier. The block diagram of remote
experiment “measuring I-V characteristic of the diode” is in
Fig. 1.
Figure 1. Block diagram
characteristic of the diode.
of
remote
experiment
“measuring
I-V
V.
REMOTE LAB – EXPERIMENTS WITH SEMICONDUCTOR
DEVICES
Remote laboratory with semiconductor devices is the next
in the series of remote laboratory in the Department of Physics,
Faculty of Education Masaryk University in Brno, Czech
Republic. This new task enlarges the existing remote tasks like
Meteorological station, Natural and driven oscillation and
Measuring on Photovoltaic Cell (see www.ises.tym.cz [3]).
After completion it will allow measuring the basic parameters
of semiconductor devices and will be demonstrate some
application of it. The main themes are PN junction and diode,
Transistor, Thyristor, Solar cell, Integrated circuits. It is used a
new approach, so emphasis is build a more simple experiments,
what should be a more usable for users, especial for students.
Operation and access in the workplace is 24 hours a day, which
is one of the advantages of remote-controlled experiments. If it
is suitable, the lecturer can present some device characteristics
directly during the lesson.
The Web page representing the I-V characteristic of the
diode is in Fig. 2. It can be seen that students can observe via
web camera the “live” response of both voltmeter and
ammeter. To be more convincing that it is real experiment we
use the classic analog apparatus in our experiment (attention to
the used range). Students can export the measured data for the
further treatment. Moreover we add the necessary theoretical
support on the webpage.
Figure 2. Web interface of remote measuring I-V characteristic of the diode
978-1-4577-1746-8/11/$26.00 ©2011 IEEE
21–23 September 2011, Piešťany, Slovakia
14th International Conference on Interactive Collaborative Learning (ICL2011) ̶ 11th International Conference Virtual University (vu'11)
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VI.
SUMMARY
The on-line laboratories respond to current trends in
increasing the number of students, while reducing contact
teaching. Remote laboratories also reflect the contemporary
trends of incorporation of the computerized activities in
everyday life.
The new multiple task solution for the construction of the
remote laboratory is more demanding, on the other hand it
leads to cost savings and to better usage of existing hardware of
remote laboratory. The main idea presented by this new
solution is the modification of a very universal school
measuring system ISES to application of remote laboratories.
The new set of experiments with semiconductor devices
primarily serves to students of physics and technical education
at Faculty of Education, Masaryk University; however it is
open to public. In such a way we increase the number of
students performing practical tasks. Students have the
opportunity to repeat and to use an experiment for longer time
compared to experiment in classical school’s laboratory.
Together with learning support, which is the part of the website
of remote laboratory, students can fix the theoretical
knowledge acquired during theoretical training. The laboratory
gives the more attractive view on semiconductors.
Website for all experiments run at our remote laboratory at
Department of Physics at Faculty of Education, Masaryk
University Brno is located at http://ises.tym.cz/.
ACKNOWLEDGEMENT
This work was supported by Project 2730/2011 of the
Czech University Development Fund (FRVŠ).
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[2]
[3]
SLÁDEK, P., PAWERA,L., VÁLEK, J.: Remote laboratory – new
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Science 12 (2011), 164-167, Elsevier ISSN 1877-0428 .
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laboratoře v Brně na PdF MU. Dostupné z WWW: <http://ises.tym.cz/>.
978-1-4577-1746-8/11/$26.00 ©2011 IEEE
21–23 September 2011, Piešťany, Slovakia
14th International Conference on Interactive Collaborative Learning (ICL2011) ̶ 11th International Conference Virtual University (vu'11)
Page 476