1. 1 March 2011
VISI
IR
INST LATIO & STA
TALL ON ART-U
UP
GUIIDE V
V.1
Electrical a Compute Engineering Department
and er g t
Spanish Un niversity for D
Distance Educ
cation-UNED
Authors: Mohamed T Tawfik
Sergio Mar rtín
Charo Gil
Pablo Losaada
Alberto Pessquera
Elio Sancristobal
Gabriel Díaaz
Juan Peire
Manuel Castro
This w
work has been sponsored by the Span nish Science and Innovation Ministry through the project
e
TIN22008-06083-C
C01/TSI “s-Labs – Open s
services integ
gration for d
distributed, r
reusable and secure remote and
virtu laboratories”
ual

2. Summary
In December 2010, the Electrical and Computer Engineering Department of Spanish University for
Distance Education (UNED) [1] installed a Virtual Instrument Systems in Reality (VISIR) [2]. VISIR is a
remote laboratory for undergraduate electric and electronic circuits practice. It allows a student to
wire a real circuit remotely and get results from real instruments on their PC screen. The purpose of
UNED is to apply it, the second semester of this academic year 2010-2011, on the practice of the
undergraduate engineering grades. On the other hand, to work on its development and integration
with other outstanding learning technologies and research areas in which the department is currently
researching to improve and enrich distance education. For instance, learning management system
(LMS), fingerprints, mobiles, remote laboratories, web services, etc. UNED aims to be an active
member in the VISIR community by sharing its lab resources and experiments with the rest of the
community to enhance the experimentation skills in the electric and electronic engineering fields.
Furthermore, it aims to bring out satisfactory results with respect to the practice as well as the
research areas directed to the enhancement of the distance education quality level.
This work reflects the acquired experience during the set up and the installation process of VISIR
at UNED. The guide contains all the stages of the installation and the necessary configurations
required for the VISIR start-up, correct usage and administration. This work aims to be a reference for
any university interested in setting up a VISIR and to be a one more contribution from UNED to its
community.

3. Table of Contents
1. INTRODUCTION ..................................................................................................................................... 6
2. HARDWARE DESCRIPTION ................................................................................................................. 7
2.1. PXI-Platform ........................................................................................................................................................................................ 8
2.2. Relay Switching Matrix .................................................................................................................................................................. 9
2.2.1. Component List ........................................................................................................................ 14
2.2.2. Max lists ................................................................................................................................... 17
3. SOFTWARE DESCRIPTION AND OPERATION CYCLE ................................................................. 18
3.1. Web Interface .................................................................................................................................................................................. 19
3.2. Experiment Client .......................................................................................................................................................................... 19
3.3. Measurement Server .................................................................................................................................................................... 22
3.4. Equipment Server .......................................................................................................................................................................... 23
4. INSTALLATION .................................................................................................................................... 26
4.1. LabVIEW ............................................................................................................................................................................................ 28
4.2. NI Device Drivers ........................................................................................................................................................................... 28
4.3. Relay Switching Matrix Driver ................................................................................................................................................. 29
4.4. Component List ............................................................................................................................................................................... 29
4.5. Equipment Server Software ...................................................................................................................................................... 30
4.6. Measurement Server .................................................................................................................................................................... 31
4.7. Web Server ....................................................................................................................................................................................... 33
4.7.1. Text_WIKI Package ................................................................................................................. 33
4.7.2. Smarty ....................................................................................................................................... 34
4.8. Web Interface .................................................................................................................................................................................. 34
4.8.1. Database.................................................................................................................................... 35
4.8.2. HTTPS ...................................................................................................................................... 35
4.8.3. Config.php ................................................................................................................................ 38
4.9. Experiment Client .......................................................................................................................................................................... 40
4.9.1. Config.xml ................................................................................................................................ 40
4.9.2. Library.xml ............................................................................................................................... 40
4.10. Getting Started ................................................................................................................................................................................ 41
5. CONCLUSION AND FUTURE WORK ................................................................................................ 42
REFERENCES ............................................................................................................................................... 43

4. Glossary
API Application Programming Interface
DPST Double pole, single throw
GND Ground
GPIB General Purpose Interface Bus
HTML Hypertext Markup Language
I2C Inter-Integrated Circuit
IC socket Integrated circuit socket
IEEE Institute of Electrical and Electronics Engineers
IP Internet Protocol
IVI Interchangeable Virtual Instruments
LabVIEW Laboratory Virtual Instrumentation Engineering Workbench
LMS Learning management system
LXI LAN Extensions for Instrumentation
NI National Instruments
PXI PCI Extensions for Instrumentation
SOAP Simple Object Access Protocol
SSL Secure Socket Layer
TCP Transmission Control Protocol
TLS Transport Layer Security
USB Universal Serial Bus
VISA Virtual Instrument Software Architecture
VISIR Virtual Instrument Systems In Reality
[3]

5. Figure Index
Figure 1. Common traditional instruments in an undergraduate ............................................................... 7
Figure 2. Relay switching matrix ................................................................................................................. 9
Figure 3. Component Board ...................................................................................................................... 10
Figure 4. Two leads components connected to DPST relays .................................................................... 10
Figure 5. Internal connection of a resistance connected to relay one and to the nodes (B, C) ................ 11
Figure 6. Internal connection of instruments with the nodes of the matrix ............................................... 12
Figure 7. A graph with 5 nodes and 10 branches ...................................................................................... 13
Figure 8. A circuit of 5 nodes and 3 components ...................................................................................... 13
Figure 9. Numbering single and dual pole relays on the component board ............................................. 14
Figure 10. Components installed in the component board ........................................................................ 15
Figure 11. Internal connection of the 6V power source using shortcut wires........................................... 15
Figure 12. Internal connection of the 6V power source using single pole relays ..................................... 16
Figure 13. Operational amplifier connection ............................................................................................ 16
Figure 14. Component list ......................................................................................................................... 17
Figure 15. A max list for an operational amplifier circuit ........................................................................ 17
Figure 16. An overview about how VISIR works ....................................................................................... 18
Figure 17. VISIR web interface ................................................................................................................. 19
Figure 18. Client selects available modules .............................................................................................. 20
Figure 19. Virtual workbench of VISIR ..................................................................................................... 20
Figure 20. Pull-down component list menu ............................................................................................... 21
Figure 21. Measurement server running ................................................................................................... 22
Figure 22. Equipment server software running ......................................................................................... 23
Figure 23. The role of IVI in the frontal panel and the platform selection ............................................... 24
Figure 24. Overall operation process of VISIR ......................................................................................... 25
Figure 25. VISIR connected at UNED ....................................................................................................... 26
Figure 26. Connection of the DMM and the oscilloscope ......................................................................... 27
Figure 27. Connection of the DC power supply and the function generator ............................................ 27
Figure 28. Instruments defined in the Measurement & Automation Explorer .......................................... 28
Figure 29. Relay switching matrix defined in the Measurement & Automation Explorer ........................ 29
Figure 30. EquipmentServer.ini file .......................................................................................................... 30
Figure 31. Create wiki page ...................................................................................................................... 41
[4]

6. Table Index
Table 1. The role of each component of the NI PXI-platform……………………………………………………………..…....8
Table 2. Board label and I2C address scheme……………………………….…….…………………………………………………13
Table 3. The VISIR oscilloscope capabilities.………………………..………………………………………….……………………24
[5]

7. 1. INTRODUCTION
The Signal Processing Department (ASB) at Bleking Institute of Technology (BTH) in Sweden together
with National Instruments in USA (as a supplier of instruments) and Axiom EduTECH in Sweden (as a
supplier of education, technical software, and engineering services for noise and vibration analysis) have
launched the Virtual Instrument Systems in Reality (VISIR) Project in the end of 2006. It is an open source
remote laboratory project, financially supported by BTH and the Swedish Governmental Agency for
Innovation Systems (VINNOVA).
In December 2010, the Electric and Computer Engineering Department of UNED installed a VISIR with
the aid and guidance of the project founder Ingvar Gustavsson, together with the two engineers, Johan
Zackrisson and Kristian Nilsson, from Bleking Institute of Technology (BTH). This guide is an installation
reference from the Department. It includes the gained experience during the installation. The guide consists
of four main chapters. The first chapter (Hardware Description) describes the VISIR hardware components
types, models and their suitable connection. The second chapter (Software Description and Operation
Cycle) explains the VISIR operation cycle and the software role of each part during the operation and its
source building. The third chapter (Installation) shows the VISIR installation step by step process at UNED
and all the configurations needed to get it to run. The Fourth and the last chapter (Conclusion and Future
works) discusses the main parts on which a future work could be realized , on the one hand, for the VISIR
development and integration, and on the other hand to Develop the available remote lab technology and
enhance distance education.
Most of the compiled information in this guide is retrieved from documents released by the project
founders through the project webpages [2] [3], all these documents are freely accessible. This guide
provides complementary information to that is found in the project web pages. Accordingly, before
installing a VISIR, the resources of the project web pages should be considered first.
[6]

8. 2. HARD
DWARE DESCRIP
PTION
The common traditiona instrumen in an u
T n al nts undergraduat engineeri
te ing laborato for elec
ory ctric and
elect
tronic circui Figure 1, are: a po
its, ower supply a function generator, a digital m
y, n , multi-meter (DMM);
brea
adboard and an oscillosco
ope.
Figure 1. Common traditional instrument in an underg
ts graduate
engineerin laboratory f electric and electronic cir
ng for d rcuits
In VISIR, the instrume are repla
n ese ents aced with an equipment platform, w
n which is suite for remot control
ed te
1
such as PXI (PC eXtension for Instrum
h CI ns mentation) [4], LXI (LA eXtensio for Instru
AN ons umentation) 2 [5] and
3
IEEEE-488or GPI (General Purpose Int
IB terface Bus) [6]. The current VISIR is based on PXI. In ad
R o ddition, a
relay switching matrix is connected to the PXI eq
y quipment plaatform. The matrix con nnects the diigital pxi
instr
rument cards to the comp
s ponents inst talled inside the matrix. By this way it possible to design an wire a
y, nd
real electronic c
circuit remot tely thanks t this matri In this part, all the V
to ix. VISIR hardw ware compon nents are
goin to be desc
ng cribed, illustr
rating the funnction of eac of them.
ch
1.
1 PXI (PCI eXtensions for In nstrumentation) is a rugged PC- -based platform for measureme and automati systems. Wi PXI, you
ent ion ith
can select t modules (ins
the struments) from a large number of vendors and easily integrat them into a si
r d te ingle PXI system PXI uses
m.
PCI-based t technology and an industry stan ndard governed b the PXI Syst
by tems Alliance (P
PXISA) to ensur standards com
re mpliance and
system interroperability.
2.
2 LXI is the power of Ethern and the Web applied to Te & Measurem
net est ment offering you new possibilit in test syste
u ties ems – local,
remote, disttributed, time-aw ware. LXI is the current and fut
e ture standard for Test & Measur
r rement. It's seen the fastest ram
n mp-up of any
communica ations standard in the history of t test industry and products fro leading test a measuremen companies.
n the om and nt
3.
3 GPIB or IEEE-488 is a sho ort-range digital communications bus specificatio It was create for use with automated test e
s on. ed a equipment in
the late 1960s, and is still in use for that pur
n rpose. It was cre
eated as HP-IB (HHewlett-Packard Interface Bus).
d .
[7]

9. 2.1. PXI
I-Platform
m
The
T PXI plat tform consis of instrum
sts ment module cards, a co
e ontroller car and a cha
rd assis in whic all the
ch
1
card are suited All the pl
ds d. latform com
mponents are manufactur by National Instrum
e red ments (NI) [7]. For
ever componen there are a various m
ry nt, models depen
nding on its technical characteristic Table 1 i
cs. illustrates
the r of each component a its available model a UNED
role and at
Table 1. Th role of each component of the NI PXI-pla
he f atform
NI PXI-Ch
hassis NI
N PXI-Mod
dules NI-P Control
PXI ller
Fun
nction: It is the backbone of the PXI
s e Or NI PXI-Instruments, The modules card ds It is an e embedded PC, which is
em in which all instrument
syste that substitut the instrum
te ments. They ar re plugged int the NI PXI-Chassis. It
to
cards (NI PXI-mod
s dules) and NI plugged into t NI PXI-Cha
the assis. All of thes
se comes with standard featur such as
h res
PXI-controller are pl
lugged into. cards can be a
added and remov depending o
ved on an integrate CPU, hard dr
ed rive, RAM,
the demands. Ethernet, video, keyboa ard/mouse,
serial, USB Microsoft win
B, ndows etc.
All these ddevice drivers a already
are
installed. Hence, it elim
H minates the
need for an external PC. H
n However, it
could be repplaced with a PC
C.
• NI PXI-Chassis (N PXI-1031).
I NI • NI PXI-DC Power Supply ( PXI-4110).
C (NI • NI-PXI Controller (NI PX
C XI-8105).
Model
M
• NI PXI-Dig
gital Multi-meter (NI PXI -4072)
r ).
inst
talled at
UNNED: • NI PXI-Fun
nction Generator (NI PXI-5412).
r .
• NI PXI-Osc
cilloscope (NI PX
XI-5114).
1.
1 National Innstruments is a l
leader company for production of automated t
y test equipment a virtual instr
and rumentation soft
tware. Their
software prooducts include L
LabVIEW, LabW Windows/CVI, T
TestStand, etc. T
Their hardware p
products include VXI, VMEbus, PXI, GPIB,
I²C, and oth industrial aut
her tomation standar
rds.
[8]

10. 2.2. Rel Switch
lay hing Matri
ix
It is a stack o PCI/1041 sized boards [8] which act as a circ
t of s cuit-wiring ro
obot. It is m
manufactured in BTH.
d
It is designed for low freque
r ency analog e
electric and electronic ci
ircuit experi
iments and cconsists of in
nstrument
and component boards. Eac instrumen board (DM Oscillo
ch nt MM, oscope, Powe source an function g
er nd generator
Boar correspo
rd) onds to its NI PXI-Devi in the N PXI-Chas and con
N ice NI ssis nnected to it using eithe coaxial
er
cable or cords, Figure 2.
es
Figure 2. Re switching matrix
elay
Relay switch
R hing matrix can hold up to 16 com
p mponent boards. Each component board comp prises 10
sock for comp
kets ponents with two leads (
h (Each socket is connecte to a doubl
t ed le-pole singl
le-throw rela DPST)
ay
and two 20-pin IC sockets for complex circuit conn
f nections. Th relay sw
hus, witching matr can cont
rix tain up to
16×1 relays as maximum. Two leads component occupy on relay wh more leads compon
10 s . ts ne hile nents e.g.
amplifier, occup more relay Figure 3. Putting the switching m
py ys, . matrix into a closed case is not recom
e mmended
becaause it should be easy to swap comp
d ponents and r
rewire brancches. Howev it is very important t protect
ver, y to
the s
switching ma atrix from no
on-qualified persons.
d
1.
1 PC/104 is a common international embedde computer stan
ed ndard controlled by the PC/104 C
Consortium.
[9]

11. Figure 3. Component Bo
oard
According to the data s
A o sheet, the m
maximum car current of the relay is 2 A an the minim
rry y nd mum life
8
expe
ectancy is 3
3×10 operat tions (appro
oximately tw operation per secon continuously for fiv years).
wo ns nd ve
Figu 4 shows t leads co
ure two omponents co onnected to DPST relays inside the m
matrix.
Figure 4. T leads comp
Two ponents conne
ected to DPST r
relays
[10]

12. In relay swit
n tching matri each boa has a ce
ix, ard ertain number of relays controlling the interco
s g onnection
betw
ween the boa compone and the b
ard ents board. Howeever, there a common nodes propa
are agating with all the
hin
boar to conne them tog
rds ect gether, creati a node b
ing bus. These nnodes are diivided into two groups, the first
,
conttains the nod A-I and 0 (GND). While the s
des d second conta ains the nod X1-X6 and COM as seen in
des a s
figur 3.
re
Figure 5 expl
F lains the inte
ernal connec
ction of a commponent in the compon nent breadboa The com
ard. mponents
can be connecte only to t nodes of the first gr
ed the f roup depend
ding on the components distributio on the
on
commponent boar Figure 6 shows the internal co
rd. onnection of the instrum
f ments with the nodes in
t nside the
matr The grou terminal of the func
rix. und ls ction genera and the o
ator oscilloscope are hardwir to node 0 (GND).
e red
The function gen nerator outp can be co
put onnected to nnode A only While the oscilloscope channels a well as
y. e as
the D
DMM chann are dyna
nels amically con
nnected to an node depe
ny ending on th user circui design and they are
he it d
not llisted in the component list design. T Power s
The source conne
ectors (0, CO +6V, +20V, -20V, A
OM, AUX) are
connnected intern nally to the node 0 (GN and th nodes of the second group (CO
GND) he OM, X1, X2, X3, X4)
respe ectively, the depending on the com
en g mponent list design (see componen list), they are connect to the
t e nt ted
first group (by a shortcut wi as seen in figure 3 or by two rela switches i series) as the second g
ire n r ay in group are
not ssupported in the current software ver
n rsion.
Figure 5. Int
ternal connecti of a resista
ion ance connected to relay one a to the node (B, C)
d and es
[11]

13. Fig
gure 6. Internal connection of instruments with the nodes of the matrix
l f
[12]

14. The
T complex of the matrix depend on the nu
xity m ds umber of nodes it have e.g. from a matrix with N nodes
we c obtain N (N-1)/2 br
can N. ranches. How
wever, the c
current matri which hav 10 nodes (A-I, 0) is s
ix ve s sufficient
for undergraduat Engineeri practice. Figure 7 sho the num
u te ing ows mber of brancches (10) co
ould be obtai
ined from
a5n node circuit.
Figur 7. A graph w 5 nodes an 10 branches
re with nd s
For
F instance, if we conne a resistan (R1) to th nodes (A, B), a resista
ect nce he ance (R2) to the nodes (B C) and
B,
a res
sistance (R3) to the node (D, E) as s
) es shown in fig
gure 8, we wo
ould have to consider so facts suc as:
o ome ch
• The DDMM chann nels are dynnamic but th nodes ar not, so w can meas
he re we sure R1, R2, R3 and
,
R1+R To measu R2+R3 (
R2. ure (nodes B, E) we have to make a sho
), o ortcut betwe the node (C, D).
een es
The shhortcut is a single wire t connects two nodes and occupie one relay as seen in th relay 3
s that s es he
of the matrix of figure 3. If th user conn
e fi he nects R2 and R3 in serie the intern shortcut r
d es, nal relay will
be connnected autoomatically to combine th two nodes the user do
o he s, oesn’t have t draw it.
to
• The fu
function gene erator is con
nnected only to the node (A, 0), so to connect it to any oth node,
y es o her
we shhould have a shortcut bet tween the no A and the other node
ode e.
Figur 8. A circuit o 5 nodes and 3 components
re of d s
In the matrix, a matrix Controller (PI
n C IC18F4550) hosted on t source board commu
) the unicates with a board
h
conttroller (PIC1
16F767) on eeach board v a bus [8], so that, eac board has a label, whi correspo
via , ch ich onds to an
addrress, which w be need later for writing the component list file. Ta
will ded r e t able 2 shows each board label at
s d
UNE with its e
ED equivalent I2C address.
Tab 2. Board lab and I2C add
ble bel ddress scheme
Bo
oard Type Board Labe
el I2C Add
dress
Co
omponent board 1 1 COMP 1
Co
omponent board 2 2 COMP 2
Etc.
Os
scilloscope b
board 16 OSC 16
DM board
MM 17 DMM 17 7
Etc.
So
ource board 24 SRC 24
[13]

15. 2.2.1. Com
mponent Lis
st
The
T compone list descr
ent omponents a instrume 1 in the m
ribes all the installed co and ents matrix to ma them
ake
know to the so
wn oftware. The is only o compone list per s
ere one ent switching m
matrix. Next, some guideelines are
given to list instr
ruments and component in the com
d ts mponent list f
file.
 Befor listing a co
re omponent w have to co
we onsider a ver important remark. The are four dual pole
ry ere
relays in the comp
s ponent board that can be replaced b eight sing pole relay as shown in figure
d e by gle ys
9. The 10 dual pole relays a numbered 1, 2,3,5,7,
are d ,8,9,10,11 and 13 respe ectively. Wh if we
hile
replac four of the with 8 si
ce em ingle pole relays, they w be numbe
will ered (1-14) respectively.
r .
Figu 9. Number
ure ring single and dual pole rela on the comp
d ays ponent board
 The t leads components (R C, SHORT
two R, TCUT, L, etc are listed as the follow
c.) wing:
<Com
mponent typ
pe>_<board label>_<re
d elay numbe
er> <Node
e1>< Node2 <etc.>
2> <Value>
<
For instance, the components installed in the compo
n onent board of figure 10 will be described as
0
ollowing:
the fo
- R_2_1 I IH 10K : represents a resistor of 10K ohm installed on the relay 1 and
s ms
connected to the nodes (I, H) in th board 2.
s he
- SHORTCU UT_2_3 HG represents a shortcut installed on the relay 3 and connect to the
G: n ted
nodes (H, G) in the bo
oard 2.
- C_2_4 AB
A 10n: represents a capacitor of 10n far installed on the rela 4 and
: r rad d ay
connected to the nodes (A, B) in th board 2.
s he
If a c
component ddemands mo than one relay to be c
ore connected to the circuit, we separate the two
o , e
relay connection by the sig “:”. For example, “
y ns gn “R_1_1:8_10 E F 1
0 10k” means that, by
s
activating rely 1 on board 1 and rely 10 on board 8 a resistor with the va
0 alue of 10k oohms are
going to be conne
g ected betwee node E an F.
en nd
1.
1 The DMM a oscilloscope connections are fixed and are n listed in the c
and e e not component list.
[14]

16. Figure 10 Components installed in the component b
0. e board
 The fu
function gene erator is con
nnected to th node “A” internally th
he hrough the r
relay 1 on th source
he
board (board labe = 24) and its ground is hardwire to “0” th
d el d d ed hrough the reelay 5 on th source
he
board it can be lis as “VFG
d, sted GENA_24_5 A 0”1.
 The nnodes of the second gro (X 1-X6 and the n
e oup 6) node COM a not supp
are ported in the current
versio of the sof
on ftware and m not be used in the component list. The pow supply t
must wer terminals
(6V, +
+25V, -25V a COM) a connecte internally to the nodes (X1, X2, X3 and 0) respectively
and are ed s X
throug the relays (3, 4, 5 ad 2) on the so
gh s d ource board (board label= 24)1. The power supp could
e ply
be connnected to th nodes of t first grou (A-I) by e
he the up either one of the followi two ways:
f ing
 Shortcut w wires connec cting the (X
X1-X3) node to the nod of the f
es des first group (
(the node
COM is ha ardwired to the node 0). For exampl figure 11 explains the internal co
. le, onnection
of the 6V DC pow source which will be describ
V wer l bed in the componen list as
nt
“VDC+6V_ V_24_3 A”.
Figu 11. Internal connection of the 6V power source using s
ure l f r shortcut wires
1.
1 The describ matrix is the one connected a UNED.
bed at
[15]

17.  Single pole relays on componen board. Fo example, figure 12 e
n nt or explains the internal
e
connection of the 6V DC power s
n source, whic will be de
ch escribed in the compone board
t ent
as “VDC+66V_24_3:10_ A”.
0_5
Figure 12. Internal c
e connection of t 6V power source using sin pole relay
the ngle ys
 For co
omponents w more th two lead more rela are used and they ar mounted o the 20
with han ds, ays re on
pin IC sockets. Fo example, the operatio
C or onal amplifie shown in f
er figure 13 ha 8 connecto Pin 1
as ors.
and 5 are not connnected, thi operationa amplifier will be des
is al scribed in th component list as
he
“OP_44_10:4_11:4 4_13 NC B D G NC C F N uA741”
NC
Fig
gure 13. Operational amplifie connection
er
[16]

18. Figure 14 sho how a si
F ows imple compo
onent list cou look like
uld e.
Figure 1 Component list
14. t
2.2.2. Max lists
x
The
T max lists are lists that describe a safe circu that cou be create and preve hazardou circuits
s all uits uld ed ent us
from being activ
m vated. It is o
only possibl to activate circuits th are safe according to a defined max list.
le hat o
Each list lists a n
h number of so ources and c
components and it descri ibes also how they can b connected to other
w be d
listed sources or components if appropri relay sw
d r iate witches are cllosed The max list forma is:
at
<Com
mponent typ
pe>_<Serial number> <Node1>< Node2><e
l < etc.> <Va
alue>
The
T serial nu umber is a se elected value to name th instrumen and the c
e he nts components. There is no need to
. o
inclu the DMM set as volt
ude M tage meter a the oscill
and loscope in th max lists b
he because they are high im
y mpedance
and do not affect the circuit so much. Fi
t igure 15 sho the max list of an op
ows perational am
mplifier circu
uit.
Figure 15 A max list for an operation amplifier circuit
5. nal
[17]

19. 3. SOFT
TWARE D
DESCRIP
PTION AN OPER
ND RATION CYCLE
VISIR is an open source project, w
V e which offers a software distribution released un nder a GNU General
U
Publ License [
lic [10]. Thus, BBTH has assigned a web bpage [3] for its software developme and insta
r e ent allation to
allow other univ
w versities and organizations to study its source and cooper
d y e rate in its d
development All the
t.
softw source buildings, p
ware packets and i
information are available in this web
e bpage. This chapter desc
cribes the
VISI operation mechanism and the software fu
IR n m unctionality and of eac part and its source building
ch
regaardless to its version as it could be up
t pdated frequ
uently.
To
T get an ove erview of ho VISIR w
ow works, imagine that you have a PC c controlling y
your PXI insstruments
and a breadboar with all th required c
rd he components connected tthrough relay If you se comman to the
ys. end nds
relay to determ
ys mine which relay should be connec
d cted and whhich should not, you w build the desired
will e
circu If you se comman to the PX instrumen terminals to determin to which node they s
uit. end nds XI nts s ne should be
connnected, you w manage to see the results on your PC. The relay switc
will e e ching matrix acts as a ro
x obot who
receiives the com
mmands sen to the rela as well as the ones sent to the PXI instru
nt ays s e uments termi inals and
inter
rprets them t a physical wiring as sh
to l hown in figu 16. In view of that, t relay swi
ure the itching matri should
ix
have an interior connection between com
e b mponents, noodes and ins
struments. It receives the commands from the
e
PC ((through USB as shown in figure 16
B) n 6.
Figur 16. An overv
re view about how VISIR works
w s
Software func
ctionality an its source building are going to be discussed a
nd e e according to the whole o
o operation
hanism proc starting from the client login till receiving th results ba on the cli screen.
mech cess l he ack ient
[18]

20. 3.1. We Interfac
eb ce
It is the webp
t page of VISIR through w which user c access t the experi
can to iment client, it is written in PHP
, n
again MySQL and installe in the w
nst ed webserver as ssigned for VISIR. It h handles all t client lo
the og-in and
auth
hentication procedures ov HTTPS protocol. W
ver When a client logs in, it generates an experimen session
t n nt
cook with the client charac
kie cteristics (stu
udent, teach priority, IP address. etc.) and sto it in the database
her, ores
to be recalled by the measur
e y rement serve for authent
er tication purp
pose, Figure 17.
Figure 17. VISIR web inte
erface
3.2. Exp
periment C
Client
It is a packag integrated in the VISIR webpag and creat by Adob Flash. It represents t entire
t ge ge ted be the
laboratory work kbench (with all its instr
h ruments, commponents an breadboa simulated through a HTML
nd ard d) an
page as an emb
e bedded object. Client is free to cho
s oose the ins
strument mo odule with wwhich he is familiar
s
rega
ardless to its model or manufacturer as shown i figure 18. By this wa it is possible to use a virtual
m r in ay,
front panel dep
t picting one-
-instrument model to c control a d
different instrument moodel as long as the
g
perfo
formance of the real inst
trument is eq qual or bette than the p
er performance of the depi
e icted instrum
ment. The
avail
lable module are:
es
• Tradittional breadb
board.
• Defau PXI-instru
ult uments inter
rfaces of Nat
tional Instru
uments.
• Digita Multi-Met (Fluke 23
al ter 3).
• Functtion generato (HP 33120
or 0A).
• Oscill
loscope (Agi ilent 54622A
A).
• DC Po ower Supply (E3631A).
y
[19]

21. Av
vailable mod
dules Selected modules
d
Fig
gure 18. Client selects availa modules
t able
However, oth modules could be bu with Ad
H her uilt dobe Flash. AAfter choosi the prefe
ing erred modul client
les,
start to wire the circuit wit the mouse and with t available componen in that se
ts th the e nts ession, and a
adjust his
instr
ruments as if he was loc
f cated inside a real labor ratory. Figur 19 shows the virtual w
re workbench o VISIR
of
wher all the in
re nstruments teerminals and componen list are available to de
d nt esign the de
esired circuit All the
t.
time spent in des
e signing the c
circuit, the c
client is occu
upying his ow PC not th real instru
wn he uments. Use manual
er
docuumentations are available at the project website [2].
Figure 19. Virt
F tual workbench of VISIR
h
[20]

22. When the client clicks on the com
W mponents but tton as show in figur 20, a pul
wn re ll-down men of all
nu
avail
lable compo
onents is shoown. This m menu can be configured and modifie through t “library.xml” file
ed the
locat in the sa location of the “brea
ted ame adboard.swf file, in the experiment client packa within th VISIR
f” e t age he
webppage source (to be discu
ussed later in the installat
n tion chapter)
).
Fig
gure 20. Pull-d
down compone list menu
ent
When the cl
W lient gets hi circuit rea and clic on the (perform ex
is ady cks xperiment) button, the c
b client PC
(exp
periment clieent) starts t call the “
to “measureme server” (see the ne section) through ex
ent ext xperiment
protoocol. The ex
xperiment pr rotocol is an XML based protocol, w
n which use eeither XML Socket API or HTTP
S
requ
uests to trans
sport the req
quest data to the measur
o rement serve The expe
er. eriment proto
ocol transmi all the
its
instr
ruments adjuustment and configuratio and the circuit design through an XML messa For exa
on n n age. ample, an
expeeriment proto request sent by a 54 function generator c
ocol 411 n could look lik
ke:
nctiongenerat
<fun tor>
g_waveform value="sine" />
<fg "
<fg
g_amplidute value="1000 />
0.0"
<fg
g_frequency value="1000 />
0.0"
<fg
g_offset value="0.0" />
<fg
g_startphase value="0.0" />
e
<fg
g_triggermod value="co
de ontinous" />
<fg
g_triggersource value="immmediate" //>
<fg
g_burstcount value="0" />
t /
<fg
g_dutycycle vvalue="0.5" /
/>
<fg
g_userdefineedwave lengt th="20" enco
oding="BASE
E64">ABCD12
234ABCD1234ABCD</fg
g_userdefined
dwave>
</functiongenerator>.
[21]

23. Web
W services prescribe XML based m
X messages co
onveyed by I Internet protocols such as SOAP to b sent to
a be
the “measureme server”. TCP/IP on p 2324 d
“ ent port does the con nnection curr rently. Henc Experime client
ce, ent
(web server) co
b ould run on a separate machine. T XML b
n e The based protoc describe what sett
col es tings and
func
ctions each instrument type can perform, independent of hardware manufacture that’s w
f er, why, it is
poss
sible to selec an instrum
ct ment simulat module i
ted independently on the ma anufacturer, also it is po
ossible to
creat new modu of instru
te ules uments that d not exist in the curren set.
do nt
3.3. Measuremen Server
nt
It is a softwar program written for M
t re w Microsoft W
Windows in C
C++ using M Microsoft Vissual C++. It receives
t
the m
measuremen requests fr
nt rom the expperiment clie each req
ent, quest is sent in a separat TCP sessi
te ion, thus,
conn and disc
nect connect are required for every reque made to t server. T requests/
r est the The /responses sh
hould not
exce 64 KB in size. Figure 21 shows a running me
eed n e easurement server on a M
Microsoft wiindows systeem.
Figure 21. Mea
F asurement server running
The
T role of th measurem server c be define in four ma steps.
he ment can ed ain
1) Authhentication: At each req quest, it verifies that the client is a v
valid user by validating t client
y the
cook generate by the web server agai the data
kie, ed b inst abase.
2) Validdation: It ac as a virtu instructor it compare the receiv circuit da with the max lists
cts ual r; es ved ata
before sending i to be exec
it cuted on the real instrum
e ments, to avvoid any dammage to inst truments.
The max lists ar created b the admin
re by nistrator (tea
acher) to de efine the per
rmitted valu of the
ues
circu componen and instr
uit nts ruments. Thi lets him to be the only responsible for any dam
is o y e mage.
3) Time e-sharing: It can handle requests fro 16 simul
e om ltaneous clie with less than a seco (1/16
ents s ond
second is the ma aximum time for each re
e equest) by qu ueuing all simmultaneous rrequests and perform
d
them sequentiall with regar to priority reservation etc.
m ly rd y, n,
4) Cont trol: After v
validating an queuing th requests, it starts to h
nd he handle them either direc using
m ctly
GPIB module or sending them sequ
B uentially ove TCP/IP through the port 5001 to the
er e
“equuipment serv ver” (see the next section). In the se
e econd case t measurem
the ment server acts as a
gatewway and co ould serve more than one equipm ment server. As it com mmunicates with the
equippment
[22]

24. 3.4. Equ
uipment S
Server
It is a stand-
t -alone equip
pment contro
oller, handli low-leve instrumen interfaces and hostin all the
ing el nt s ng
instr
rument hard dware togeth with the relay swit
her e tching matr rix. It is div
vided into t three parts, the PXI
platf
form, the rel switchin matrix an the PC th handles t commun
lay ng nd hat the nication amo them wi server
ong ith
softw installe in it. The server softw is writte in LabVIE Figure 2 And all th instrumen drivers
ware ed ware en EW, 22. he nt
insta
alled in the L
LabVIEW are IVI (Interch
e hangeable VVirtual Instru
uments) com mpliant [11].
Figu 22. Equipm server soft
ure ment ftware running
The
T equipmen server rec
nt ceives a validdated sequen
ntial experim protoco requests fr
ment ol rom the measurement
serve in separat TCP sessions over TC
er te TCP/IP throu the port 5001 and ex
ugh xecutes it th
hrough the c
connected
instr
ruments. Aft that, the results retur back to th client scre with the same sequence. The re
ter rn he een e esults are
repreesented in fo of measu
orm urements on the virtual i
n instruments..
Most of undergraduate electronic la
M e aboratories o all the un
of niversities a
around the world have common
w
equipment (osc cilloscopes, Function g generators, multi-meters DC pow supplies and brea
s, wer s, adboards)
ardless of th
rega heir model and manuf facturer type. The curr rent VISIR supports P PXI, however, other
univ
versities wou like to u another platform (L
uld use LXI, GPIB, etc.). To en nable interch
hangeability between
workkbenches an different grid nodes (
nd g (different un
niversities), V
VISIR recom mmends fun nctions and a
attributes
defin by the I Foundat
ned IVI tion [11] to be used to describe the base class capabilities and class e
e s extension
capa
abilities of th lab hardw
he ware.
Accordingly, it should b possible to create a standardize approach which is easy to ado Base
A be ed h, opt.
capaabilities are t functions of an instru
the s ument class that are commmon to most of the instruments avaailable in
the class. For ex
c xample, for a oscillosco the base capabilities mean edge triggering o
an ope s only. Other t
triggering
methhods are def fined as extension capab
bilities. The f
functions su
upported by t VISIR oscilloscope are listed
the
in ta 3.
able
[23]

25. Tab 3. The VISI oscilloscope capabilities
ble IR e
Grou Name
up Description
D n
Base Capabili ities of the IviS Scope
speciification. TThis group includes the
p
IviSco
opeBase
capabbility to acq
quire wavefforms using edge
triggeering.
Extennsion: IviScope with the abilit to ty
IviScopeWWaveformMeas calcu ulate wavefo orm measur rements, su as
uch
rise t
time or frequency.
Extennsion: IviScope with the abilit to ty
modi ify the be ehavior of the trigg gering
I
IviScopeTrigger Modi ifier
subsyystem in th absence of an expe
he ected
triggeer.
Extennsion: IviScope with the autom matic
IviScopeAuto- Setup
configuration ab bility.
The
T goal of th IVI Foundation is to support 95 p
he percent of th instrumen in a partic
he nts cular class. T VISA
The
(Virt
tual Instrum
ment System Architecture standard [12] is accep
e) pted too but the instrum
t ment function should
ns
be th
hose defined by the IVI standard. Fi
d igure 23 exp
plains the fle
exibility (pro
ovided by IV of selecti of the
VI) ion
front panel and the platform
tal d m.
Figure 23. The role of IVI in the frontal panel a the platform selection
and m
After understanding the software f
A function of each part s
sequentially, we can su
, ummarize th whole
he
oper
ration proces as shown in figure 24.
ss .
[24]

26. Figure 24. Overall operation process of VISIR
u l o
[25]

27. 4. INSTA
ALLATIO
ON
Before startin with the installation an overvi
B ng e n, iew on the connection is given. A mentione in the
As ed
prev
vious chapter the web se
r, erver, the meeasurement server and th equipmen server sof
he nt ftware, each could be
runnning on a sepparate comp puter and the can comm
ey municate wit each other by TCP po
th r orts. At UNE all of
ED
these servers are running on the same m
e e n machine (NI PXI-Contro
I oller), however, they sti communic with
ill cate
each other throu TCP por The hard
h ugh rts. dware compponents shou be conne
uld ected properl before sta
ly arting the
insta
allation. All the matrix cards should be connecte properly t their corre
c ed to esponding in
nstruments in the PXI
n
platf
form. The co omponents a distribute on the co
are ed omponent bo oard. The mmatrix is conn
nected to an external
n
(12 V) dc power source and to the controller through a USB cab A PC scr
V r h ble. reen, a keybo
oard and a m
mouse are
connnected to the controller. Figure 25 s
e show the VISIR connect tion at UNE Windows XP is the o
ED. s operating
syste of the co
em ontroller.
Figure 25. VIS connected at UNED
SIR
To
T understan the instrum
nd ment connec ctions, figure 26 and 27 explain the internal con
e nnection bettween the
PXI- -Instruments and the vi
s irtual board After chec
d. cking all th connectio
he ons, software installation can be
e n
start Coming up next, the step by step installation process.
ted. e p n
[26]

28. Figure 26 Connection o the DMM an the oscillosc
6. of nd cope
Figu 27. Connec
ure ction of the DC power supply and the functi generator
C y ion
[27]

29. 4.1. Lab
bVIEW
LabVIEW is the platform with which the equipm server s
L m h ment software is d
developed. It must be ins
t stalled on
the machine tha runs the equipment se
m at erver softwa The equi
are. ipment server software that include a relay
es
switc
ching matrix version 4 is compatible with LabVIEW v
4.1 version 8.6 or higher. LabVIEW l license is
purc
chased from N
National Ins
struments [13]. LabVIEW 2010 is the version ins
W stalled curre
ently at UNE
ED.
4.2. NI D
Device Dr
rivers
All
A the NI PX XI-Instruments (DMM, Oscilloscop DC Powe Supply an Function Generator) mounted
pe, er nd
in th PXI chassis and described in t equipme server software mu be define in the L
he the ent ust ed LabVIEW
platfform. The N device driv comes w the Lab
NI vers with bVIEW licen however it is recomm
nse, r mended to install the
lates NI device driver versi from the National in
st ion e nstruments w
webpage to mmake sure th it contain all the
hat ns
1
funcction files (.v files) nee
vi eded to run the equipm
ment server s
software. Ni device driv
i vers version released
n
Aug 2010 [14 is the vers
gust 4] sion currently at UNED.
T check the installed devices in the LabVIE platform go to star menu P
To e EW m, rt Programs National
Instr
rumentsMMeasurement & Automati Explorer In Devices and Interfa
ion r. s faces, if you click the dro
op-Down
men beside the PXI chass all the i
nu e sis, installed instruments wi appear w their rel
ill with lated slot nuumber as
show in figure 28.
wn
Figu 28. Instruments defined in the Measurem & Automa
ure n ment ation Explorer
1.
1 The “.vi” files for each inst
trument are requ
uested to execute the equipment server. They are found inside th “inst.lib” and the “vi.lib”
e e he d
folders, both folders are fou within the La
h und abVIEW installaation folder.
[28]