Academic Open Internet Journal ISSN 1311-4360
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Volume 23, 2008
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TESTING TOOL SET FOR SPACE
Dichko
Bachvarov*, Bojan Kirov**, Georgi Stanev***,
Rumyana
Krasteva*, Ani Boneva* , Veselin Georchev*
*CLMI-BAS,
Acad. G. Bonchev Str., Bl. 1, veso@clmi.bas.bg
**STIL-BAS,
Acad. G. Bonchev Str., Bl. 3, bkirov@space.bas.bg
***SRI-BAS,
Acad. G. Bonchev Str., Bl. 3, gstanev@space.bas.bg
Abstract: This paper presents an hardware and software
tool for testing of the electrical and communication parameters of monitoring
device units, purposed for working on the board of Russian segment of International
Space Station (ISS).
These devices, incorporated in project “Obstanovka”, will make measurements of
the electromagnetic fields and plasma-wave processes
occurring in the ISS near-surface zone (NSZ). The tool integrates hardware and software components for testing of
the functionality of the Bulgarian devices DP (designed in SRI-BAS) and LP
(designed in STIL-BAS), included into the project
Keywords:
space plasma
research, scientific device unit,
project “Obstanovka”, RS422, functional testers
1. INTRODUCTION
1.1.
Project
“Obstanovka”
The monitoring of
the plasma- wave processes is based on the physical idea, supposing that the plasma
(including plasma in the outer space of ISS) is a dynamic medium [2]. The project
“Obstanovka” has to create a databank of knowledges for electromagnetic fields and plasma-wave processes, being occurred in the near-surface zone (NSZ) on ISS.
Fig.1.
Location of the Bulgarian measuring blocks outside of ISS
Next task of the
project is the discovering the influences
over plasma components under the near-Earth space (NES) (including influences having artificial causes). On Fig. 1 is
shown the Russian segment of ISS and
the work location of the scientific instruments. There are two
containers, denotes as CWD1 and CWD2, for mounting of different measure blocks
(scientific instruments). In each one of the containers are mounted two
Bulgarian instruments-named LP-1, LP-2 (of type LP), DP-1 and DP-2 (of type
DP), as and set of other instruments. Each of the scientific instruments
measures different plasma-parameters. Fig.2 shows the connections between
different devices forming two local networks (by one of each of the
containers), [5].
Fig. 2. Connections between
scientific instruments.
Each of the local networks
includes a set of measurement devices and Data acquisition control unit (DACU), connected by RS422 bus (DACU is connected to each of devices
from its group via a separate RS422 bus and uses a separate port for
communication with this device. Some of the devices use a different type
interface communication, but LP and DP use RS422) [1].
It is defined inherent
logical communication protocol, unified for all of the devices communicating on
RS422. This protocole determinates the transactions on the bus and data
presentation.
As is shown on Fig.2, DACU1 and DACU2 are connected into high level LAN,
including these devices, Hub, BSTM (Block of Storage of Telemetry Information) and on the board
of ISS computer.
1.2
Scientific experiments (with LP and DP devices)
With the Bulgarian instrument
units, LP and DP, included into the project “Obstanovka”, have to be doing
following scientific experiments:
Ø
LP is intended for measurement variations of the
conductivity of plasma using “Langmiur probe” method. The instrument has
ability for controlling of the connected to it probe potential and measurement
of the incoming current (from the near space plasma), calculating important
plasma characteristics [3].
Ø
DP is intended for measurement of the voltage
potential variations of surface of ISS toward the near Space (in long time
interval), using special spherical probe, connected to the device.
Each of the devices collects
of data, saves and sends it to the DACU. DACU integrates the received
information and transmits it to a base computer, resident on the ISS board (by
Ethernet bus).
2.
MAIN FEATURES OF TESTING TOOL SET
The tool set includes
hardware and software components.
The hardware components
include passive and active electronic blocks, User station based on PC,
interface cables and other devices (it is possible to add and second PC for
communication control) allowing test of the system in realistic conditions.
The software components are
divided in to three groups:
Ø
test programs built in to the instrument units,
activated from User station;
Ø
test and simulation programs built in to User station;
Ø
test programs built in
secondary PC used during the communication test time.
Test configuration schemas
for DP and LP experiments are shown on fig. 3 and fig.4.
The test scenario includes
follow steps:
Ø
Communication tests – tests for communication protocol
and traffic conditions performance;
Ø
Connection tests – tests of connectivity between the
device units and DACU.
Ø
Functional test
- test of correct functioning of measure subsystems of the devices;
Ø
Simulation test – test based on simulation sequences,
generated by User station;
2.1.
Features of functional tests Testing tool
The Testing tool software is
designed as packet based on Tcl scripts in PC and library of C functions,
running in to the instrument units. It is realized as instrumental and graphic
user interface (API).
The graphic interface supports active menus
(built in to the help menu). This approach allows the user selection of the
concrete test program together with help information connected to it. There are
specific test procedures for each of two instruments units – LP and DP. It is
included additional test procedure, allowing full simulation of the “flight”
work mode of the tested instrument units.
Each of the tests generates
result documentation (saved in its inherent directory), having abilities for
graphic and text visualization.
A special electronic block
(CMB) is designed to work as converter between RS422 and RS232, with ability to
support the communication protocol between the instrument units and operation
station (PC). This block includes additionally a power supply (for instrument
unit) and signal generators used in the test mode time. The set of the user
station and CMB simulates external DACU communication and space plasma
parameters generation.
2.1.1. DP test configuration
DP test configuration is shown
on fig. 3 and includes primary module (DP-PM), connected to spherical probe and
secondary module (DP-SM) working as processing unit. Control and Measuring
Block (CMB) generates simulation voltage signals, under program control, to the
probe. CMB makes translation of interface protocol between RS422 and RS232
(used by DP-SM and operation station (PC)). The PC controls all test events,
generates control sequences and records the test results, using unified
communication protocol.
DP-SM is intelligent device,
processing all analog signals, received from DP-PM and supporting logical and
physical interface to PC. It measures voltage levels by 16 bits ADC, converts
the results and writes corresponded records after filtration in to his local
data base. In current test configuration DP-SM works as slave device and PC
works as master device.
Fig.3. DP test configuration
2.1.2. LP test configuration
LP device is designed for
measurements of plasma parameters, based on “Langmiur probe” methodology. It includes
circuits for voltage control and current measuriment,
data saving and communication with DACU (using unified logical protocol on
RS422 bus).
Fig.4. LP test configuration
LP test configuration
includes primary module (PM), connected to Cylindrical probe and secondary
module (SM), working as processing unit.
SM controls the voltage level
on the probe executing commands receiving from PC on RS422 bus (trough
RS232/RS422 converter built in to CMB). On the probe is generating corresponded
current reading by 16 bits ADC from SM device. After filtration and conversion of the measures, the
last are recording in to a local data
base on SM.
In current test configuration
LP works as slave device and PC works as master device. PC controls all test action
processing. It uses unified interface protocol, saves and visualizes the test
results.
2.2.
Features of Testing tool for communication test
On the fig.5 is shown the
test schema of the communication tests (the units DP and LP).
The communication tests includes tests of the bus transactions, the control of
the data stream and the protocol time conditions. Because the communication bus
is RS422, there are two one - direction differential lines connecting the
instrument unit to DACU. The control of the logical level of these lines,
during the test time, is the first task of the communications testing tool [4].
The second task is the data
control of the transmitted block during the different communication sessions.
The special device (Monitor) supports additional channel to an
external computer (Laptop). By this way
is possible to monitor of data traffic line. Using additional control line, the
Laptop can select current monitored line. Laptop software controls the monitor
work and tests transfer block validity.
Because the communication lines are galvanic
isolated from the monitor hardware, their observation hasn’t electrical
influence with them. This feature allows the test to be processed as with user
simulator station, so and with original DACU, connected to the instrument unit.
Fig. 5. Communications test
2.3.
Features of Testing tool for “connections test”
In the area of Space
applications is very importantly to control of the connections between
different communication lines. Some problems can occur because the
instrument units and DACU have independent power supply modules but they use
common interface ground. When the scientific units and DACU have “different”
grounds, it makes possible influences of the signals.
Other serious problem is a
big number of wires (and connectors) used. For example, the instrument LP uses
27 connections for different signals.
Ø
For a control of the connections, the tool uses such
device, as is shown on fig.5. This device has indicators of correct connections
of the bus lines and right bus levels.
Ø
The “Monitor” has an external power supply independent
of the bus power supply. So it has ability to observe on communication line
states at any time. This feature could be used for testing of the instrument line
standalone (without connection to DACU or simulator system).
Ø
Each of Control Measurement Block’s (CMB) has
indicators for correct consumed energy from tested unit. Other indicators are
used for showing of states of communication line. These indicators give the
user objective information of the state of communications and connections
during test time.
3.
CONCLUSION
The Testing tool set is a mix
of hardware and software solutions. It is a part of Control Testing Equipment
for Technological and Flight Control Procedures (CTETFCP) of LP and DP in the
project “Obstanovka”.
The Testing tool set is used
as for functional testing, so and for DACU functioning simulation. It is useful
and in the case of “Complex test”, including test of all devices working as
complex.
This approach is useful for
building of test configuration for different complex scientific devices working
in real-time.
References:
[1]. Batchvarov D., B. Kirov, A. Boneva, R. Krasteva, S. Klimov, K. Georgieva, Software Package for Primary Processing of
Telemetric Information, Tenth Jubilee National Conference wich
International Participation Dedicated to the 70th Anniversary of
Acad. Dimitar Mishev, Contemporary Problems of Solar-Terrestrial Influences,
Proc. ISBN 954-91424-1-8, Editor: Acad. Dr. Stoycho Panchev, 6. Session “Space
Instrumentation and Technologies”-SIT, pp. 202-205, STIL-BAS, Sofia, (20-21
November 2003).
[2]. Georgieva Katya, Boian
Kirov, Dimitar Atanassov, Ani Boneva, Impact
of magnetic clouds on the middle atmosphere and geomagnetic disturbances,
Journal of Atmospheric and Solar-Terrestrial Physics, ISSN: 1364-6826,
(Editors-in-Chief: T. Killeen, J. Plane), Elsevier Ltd, Volume 67, Issues 1-2 ,
January 2005, Pages 163-176, DOI information: 10.1016/j.jastp.2004.07.025,
http://authors.elsevier.com/sd/article/S1364682604001865
[3]. Kirov B.,
Batchvarov D., Boneva A., Krasteva R., Georgieva K., Klimov S., A Remote Upgrading of the Special Software
for the Langmuir Probe Aboard the International Space Station, 11th
International Scientific Conference “Solar-Terrestrial Influences”, Sofia,
Bulgaria, Proceedings of the Eleventh Intrnational Scientific Conference
(Edited by S. Panchev), ISBN 954-91424-1-9, Solar-Terrestrial Influences
Laboratory "Acad. D. Mishev" - BAS, (24-25 November 2005), pp.
185-188.
[4]. Kirov, B.;
Batchvarov , D.; Boneva, A.; Krasteva, R.; Georgieva, K.; Klimov, S.; Dachev,
T., A Remote Upgrading of a Space-Borne
Instrument, 36th COSPAR Scientific Assembly. Held 16 - 23 July 2006, in
[5]. http://arc.iki.rssi.ru/obstanovka/publications.htm
Technical College - Bourgas,
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