introduction to scicoslab-scicos

8/16/2019 Introduction to ScicosLab-Scicos

1/33

Introduction to ScicosLab\Scicos

Lombardi Lorenzo

September 1, 2011

This document is an abstract of my thesis in Electronic Engineering at the ni!ersity of"lorence at the Laboratory of ltrasound and #$T% $isclosure of this document is permitted free as long

as the authorship &ill be recognized and its use reser!ed only for educational and research purposes %

1


2/33

IndexIntroduction to ScicosLab\Scicos %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%1

'remise%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%(

1%1ScicosLab%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%)

1%2 Introduction to ScicosLab*Scicos%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%)1%2%1 +dd ne& bloc to Scicos%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%1-

1%( .ibliography%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%((

2


3/33

'remiseThe operating system on &hich &ere carried out the e/amples in the

document is indo&s ' S'( on &hich &ere installed !ersions )%)b- of

ScicosLab and !ersion 1%%1 of Eria Enterprise, code3named 45iacomo4, &ith

the ScicosLab 'ac 6%( % $ifferent 7Ses and * or later !ersions of the soft&aremay bring to significantly differ result &ith &hat follo&s, ho&e!er I hope that

the tutorial &ill be useful the same%

(


4/33

1%1 ScicosLab

ScicosLab is an 7pen Source soft&are pacage &hose de!elopment is carried

out by the 8ET+L+1 group enclosing some researchers belonging to I#9I+2 and

E#':( based on !ersion ) of Scilab and containing &ithin it an important toolbo/called Scicos%

Scilab is a soft&are for numerical computation that includes, &ithin libraries,

hundreds of useful features for different uses; from the mathematical calculation to the

simulation of control systems% It also offers the opportunity to design the personal

functions in :, : you can still

change the &orboo &ithout ha!ing to restart the program ?

7pen ScicosLab% To place the &oring directory to the desired folder,

type the command

cd>4'ath folder4?@

The Auotes that enclose the path of the folder used to a!oid problems

related to the presence of any spaces in the path

>es%; :;\$ocuments and Settings\folder?

To start Scicos, in the top bar, under 4+pplication4 menu, select

4Scicos4 >or run the command BScicos >?@B 3ithout AuotesC 3 In ScicosLab?

This &ill open a ne& &indo&% In this &indo&, in the top menu, go on

the 4'alette4 menu and select 4pal tree4; a third &indo& &ill appear &ith

!arious e/pandable folders containing all blocs >4palette4? usable in Scicos%

7pen the

menu 4sources4 and position itself on the bloc 45E#DS94

"ig% 1%1; 5E#DS9% bloc

1 8EThodes, +lgorithmes et Logiciels pour lB +utomatiAue, http;**&&&3

rocA%inria%fr*metalau*2 Istitut #ational de 9echerche en InformatiAue et en +utomatiAue, http;**&&&%inria%fr*

( Ecole #ationale des 'onts es des :haussFes, http;**&&&%enpc%fr*english*intDinde/%htm

)


5/33

>scrolling the mouse o!er the !arious blocs present in the menu the

name of the bloc are displayed?

$rag the 45E#DS94 bloc into the &indo& of Scicos !ia a single

clic of the left mouse button on it, hold it until it is positioned in the desired position%

Gou can mo!e a bloc already present on the plan &ith the same

system, or by right3clicing the mouse on the bloc and select 48o!e4%

5o to the menu 4Sins4 and place the bloc 4cscope4 &ith the same system

described for the bloc 45E#DS94%

'lace the mouse on the output arro& of the bloc 5E#DS9, clic

&ith the left mouse button and hold it do&n, dra& a line from this bloc the

entrance to the bloc :scope

"ig% 1%2; :S:7'E bloc%

'lace the mouse on the output arro& of the bloc 5E#DS9, clic

&ith the left mouse button and hold it do&n, dra& a line from this bloc the

entrance to the bloc :scope

"ig% 1%(; Simple e/ample of connection bet&een blocs%

#o&, on the top bar of the Scicos &indo&, go to 4Simulate4 menu and

select 49un4% This &ill open a fourth &indo& named 4ScicosLab 5raphic4 and

&hat &ill not be e/actly the sAuare &a!e that &e e/pected;


6/33

"ig% 1%); 5raph of the bloc : S:7'E resulting from the diagram of "ig% (%

The sa&tooth displayed an 4edge effect4 arising from the manner in

&hich the scope combines t&o samples by default% The mechanism is Ba littleB

complicated to e/plain and is not one of the ob=ecti!es of this introduction, but

rather to see ho& to sol!e this problem%

:lose the graph &indo& and, returning on Scicos, drag the bloc

diagram 4:L7:HDc4 from the 4Sources4 menu;

"ig% 1%; :L7:HDc bloc%

Then go on the bloc : and S:7'E, double clicing &ith the left

mouse button on it >7r by a single right clic and select the 47pen * Set4? to

change in the setup &indo& of the bloc that &ill open item 4 Accept herited

events4 from one to zero as sho&n in "ig% 1%%


7/33

"ig% 1%; Setting &indo& of bloc :S:7'E%

In this &ay on the top of the bloc :S:7'E appear a small red arro&;

8o!e the mouse on the output arro& of the bloc :L7:HDc and drag a line

>red? from here to the ne& red arro& input appeared abo!e the bloc :S:7'E;

"ig% 1%J; $iagram comprising the synchronization bloc :L7:H c%

To create segmented line, &hile you are tracing mae a single clic

&ith the mouse at the point &here you &ant to change direction%

+t this point, e/ecuting the command 4Simulate 3K run4 again, thegraph &ill sho& the sAuare &a!e desired;

J


8/33

"ig% 1%-; 5raph of the bloc : S:7'E resulting from the diagram of "ig% 1%J%

The bloc :L7:HDc force blocs connected to it to &or at the

freAuency set by him; double clicing &ith the left mouse button on this bloc

&ill open the &indo& for setting the options bloc :L7:HDc; the best &ay to

understand ho& it &ors is to do !arious tests and see &hat happens%

Try changing the 4'eriod4 by !arying it bet&een 0%001 and 1,

remembering that a greater freAuency of calculation does Not always mean

greater accuracy of simulation, but rather if it rises too high you ris

o!erloading the system &ith unnecessary calculations that in the best case do

not bring any benefit to the process of calculation and simulation%

Try also to replace the bloc 45E#DS94 &ith other blocs in the

4Soucres4 menu, for e/ample &ith the bloc 45E#SI#Df4 >to clear the bloc

45E#DS94 highlight it by clicing once &ith the right mouse button and

select B $elete 4;the cancellation of a bloc also results in the disappearance of

all the connections that this has &ith the other blocs in the chart?

-


9/33

"ig% 1%6; $iagram of "ig% 1%J &ith sine &a!e generator%

Lie the bloc 5E#DS9 >and many others?, the bloc 5E#SI#Df

allo&s you to set the desired properties >specifically amplitude, freAuency and

phase? opening the &indo& of setting the bloc properties by double clic of

the left mouse button on the bloc under consideration%

To set the duration of the simulation, in Scicos, on the menu

4Simulate 3K setup4 and change the 4"inal integration time4%

ith the 49ealtiming scaling4 option you can select the speed of the

simulation; 0 ma/imum speed permitted by the system in use, 0% graph

e!ol!es speed Doubled in respect to ho& &ould the real system simulated, 1

simulation e!ol!es in real time , 2 slo&ed by a factor of 0% and so on%

hile you are in a simulation, you can stop it using the 4Stop4

command in the menu bar at the top of the Scicos &indo&, you can then restart

the simulation from the stop point, restart from the origin or end it by the

4Simulate 3K run4 command%

To change the size of the a/es of the graph, open the settings &indo& of

the bloc :scope and edit the fields 4Gmin4, 4Gma/4 and 49efresh period4 that

indicates the length of the a/is of the graph; be careful that this does not

e/ceed the 4"inal integration time4 set in the parameters of the simulationC

To change the indications on the a/es instead, for e/ample to be able touse the chart created in a presentation or similar, clic the menu 4Edit 3K

"igures properties4 on the ScicosLab 5raphic &indo& ,and, in the &indo& of

options that &ill appear, change the 4Label4 field present in the 4Label

7ptions4 menu of the !arious tabs on the right under 47b=ect 'roperties4 menu

that appears &hen you select the 4+/es4 menu on the left% In this &ay is

possible to modify the instructions gi!en on the chart a/es, plus the title of the

graph itself contained in the field 4#ame of Scope >label M Id?%4 >see "ig% 1%?

This &ill be useful &hen &e &ill ha!e schemes &ith many graphics%

To sa!e a chart, the &indo& ScicosLab 5raphic, run the command

4Sa!e4 under the 4"ile4 menu in the top left, in this &ay >remembering to addthe e/tension 4%scg4 at the end of the name because this is not done

6


10/33

automatically by ScicosLab? you can sa!e the chart in format ScicosLab

5raphic so you can re3open later for further analysis >eg using the command

4Noom4, the t&o magnifiers present under the file menu, &hich allo& zoom in

on a specific section of the graph sho&n &ithin a rectangle that is created by

holding do&n the left mouse button and dragging &ithin the limits of the

graph?%To load a sa!ed chart, once opened a &indo& ScicosLab 5raphic, run

the command 4Edit 3K Erase figures4 and then 4"ile 3K Load4 loading the

desired graph% sing the 4"ile 3K E/port4 command you can sa!e graphics also

&ith other e/tensions >5I", .8', etc%?

The !ariables in use can be e/plicitly inserted bet&een the blocsBs

parameters of the scheme or be indicated indirectly through :7#TET of the

schema%

+s an e/ample consider the follo&ing scheme, composed of the blocs

already seen 5E#SI#Df, 5E#DS9, :L7:HDc and :S:7'E, and by the bloc '97$:T in the menu 4#onDlinear4;

"ig% 1%10; $iagram &ith magnitudes indicated by conte/t%%

The result of the simulation, after ha!ing properly set the calculation

time of the bloc :L7:HDc, is sho&n in "ig% 1%11%

Should be noted that to start a simulation is necessary that all the inputs

of the blocs included in the diagram are connected to a!oid the uncertainty of

their !alue, &hile the same is not binding as regards the outputs%%

10


11/33

"ig% 1%11; 5raph of the .loc : S:7'E resulting from the diagram of "ig% 1;10%

LetBs go bac no& to the Scicos graphic &indo& and go to the menu

4$iagram 3K :onte/t4 accessible from the menu bar at the top of the Scicos

&indo&; &ill open a te/t &indo& in &hich to enter the parameters of interest%

In the present case &e insert the follo&ing;

a = 2f1 = 2b = 3f2 = 4

Tab% 1%1; :onte/t of the diagram of "ig% 1;10%

:lic 47H4 at the bottom and go bac on the Scicos 5raphic; open the

setting &indo& of the bloc 5E#SI#Df &ith a double clic of the left mouse

button and insert in the 48agnitude4 field the !alue 4a4 defined in the conte/t

and in the field 4"reAuency >9ad * s? 4, the !alue4 f1 4as seen in "ig% 1;12%

11


12/33

"ig% 1%12; Setting &indo& of bloc 5E#SI#Df%

In this &ay the amplitude of the sine &a!e is set to the !alue indicated

by the !ariable 4a4 in the conte/t and the freAuency at the !alue f1% Then open

the settings &indo& of the bloc 5E#DS9 and modified !alues 48inimum!alue4 and 48a/imum !alue4 respecti!ely 43b4 and 4< b4, then set the field

4'eriod >sec?4 to the !alue 41 * f2 4%

Try again simulation to see the effects of the changes made to the chart%

The use of the conte/t in this &ay may seem superfluous, but &hen you

ha!e comple/ patterns, composed of many blocs nested one inside each other

in &hich the same !ariable may be repeated &ithin se!eral blocs, or in &hich

the same mathematical e/pression is repeated in more than one parameter, the

conte/t allo& to change this !ariable or this e/pression =ust one time &ithout

ha!ing to go and search for each bloc &here this is used at the ris of losing

some and allo&ing you to change the scheme faster and speed up the processtuning of the simulation itself%

.ut &hat does it mean to ha!e 4more blocs nested inside each other4O

hen you ha!e Pery large patterns, it is often possible to di!ide them into

functional sections that perform specific purposes, in this case to simplify the

understanding of the &hole schema is useful to enclose these sections in special

blocs, called 4superblocs4, so that the o!erall schema is composed of

functional superblocs connected to one another%

To create a superbloc, clic &ith the left mouse button on the Scicos

diagram in a blan space and, &ithout releasing it, dra& a rectangle that

includes all the blocs you &ant to be included in the superbloc% "or e/ample,

going bac to the first scheme, highlight +ll blocs e/cluding the bloc

:L7:HDc >you can also enter this one in the superbloc, but for our purposes

is better to not include it? in order to ha!e the situation sho&n in "ig% 1;1(%

12


13/33

"ig% 1%1(; Qighlight of the blocs of the diagram of "ig% 1;10 to be included in the superbloc%

Then clic &ith the right mouse button and select the 49egion to

superbloc4% e &ill ha!e a scheme similar to that sho&n in "ig% 1%1)%

"ig% 1%1); $iagram of "ig% 1;10 enclosed in a superbloc%

To obtain a more orderly pattern you can delete the red lin that

connects the bloc :L7:HDc to the superbloc created >5o on it &ith themouse and clic the right button and then select the 4$elete4? to mo!e the

1(


14/33

bloc nearest and reconnect the t&o in a less segmented &ay, &ithout losing

any functionality% In fact, by re3e/ecuting the command 4Simulate 3K run4 the

graph obtained &ill be identical to that obtained pre!iously%

$ouble3clicing &ith the left mouse button on the superbloc, or by

right clicing on it and selecting the 47pen * set4, you can open a secondscheme Scicos comprising the blocs contained in the superbloc%

The irregular red pentagon &ith in the number one represents the point

in &hich, &ithin the superbloc, enters the e/ternal control signal coming from

bloc :L7:HDc%

If the superbloc had more inputs, including of non3acti!ation type , &e

&ould ha!e had other pentagons >.lacs, for signals? &hile if the superbloc

had had some outputs &e &ould ha!e had some similar pentagonal blocs

indicating the outputs from the superbloc%

Gou can still add ne& inputs and outputs e!en &hen the superbloc has

already been created% To add an input to the superbloc, add the bloc 4I#Df4

a!ailable in the 4Sources4 menu

"ig% 1%1; I#Df bloc%

"or not changing too much our e/ample, open the setting &indo& of the

bloc '97$:T and change the field 4#umber of input or sign !ector4 from

4R1, 314 to 4R1@ 31@ 14 ; this adds an input to the multiplier bloc%

The operation that is performed on the inputs is a multiplication if the

input is mared &ith a 414 and a di!ision if 4314% The order in &hich the inputsappear outside the bloc are, from top to bottom, in the same order in &hich

they are listed in the input !ector from left to right%

In this &ay the pre!ious connections are unaffected, but due to the

different arrangement of the inputs on the side of the bloc '97$:T the

connection lines may no longer be straight%

To change the path of a connection mae a single clic o!er it &ith the

left mouse button; in the points &here the line changes direction appear some

&hite rectangles@ select them &ith the mouse pressing the left button and,

&ithout releasing it, is possible to mo!e the selected angle to the desired

position%

'lace the mouse on the tip of the bloc I#Df and dra& a line from this

to the ne& entrance to the bloc '97$:T% +dd to the diagram the bloc

47TDf4 a!ailable in the 4Sins4 menu

"ig% 1%1; 7TDf bloc%

'lace the mouse in the middle of the line =oining the bloc '97$:T

to the bloc :scope and, by double clicing &ith the left mouse button >or,

alternati!ely, by pressing the 4l4 >4Lin4? on the eyboard? to connect this line

1)


15/33

to the 7TDf bloc% The end result &ill be similar to that sho&n in "ig% 1%1J%

"ig% 1%1J; Inner !ie& of the superbloc of "ig% 1;1) &ith addition of inputs and outputs%

#o&, closing the Scicos 5raphic &indo& that encloses the blocs

&ithin the superbloc and returning bac to the main schema, the superbloc

&ill sho&, in addition to the acti!ation input, a signal input and an output, for

no& unused, as sho&n in "ig% 1%1-%

"ig% 1%1-; $iagram of "ig% 1;1) &ith input and output to the superbloc%

+dd in this scheme a bloc 4:7#STDm4 a!ailable in the menu

4Sources4 and another bloc '97$:T, then set the field 4:onstant4 of the bloc :7#STDm at t&o and connect it to the created input of the superbloc%

:onnect an e/tension from this ne& input to the input of the bloc '97$:T,

&hile the other input &ill carry the signal coming out of the superbloc% Then

add to the graph also the bloc 4:8S:7'E4 a!ailable in the menu 4Sins4,

&hich allo&s you to !ie& more than one graph on the same screen, and

acti!ate the input e!ent by setting to zero the !alue of the option 4+ccept

herited e!ents 0 * 1 4as done pre!iously for the bloc cscope%

.y default the bloc :8S:7'E accepts t&o inputs and then displays

t&o graphs; inside its settings &indo& you can still add ne& entries and then

display multiple graphs in one screen by setting appropriately these

parameters%

1


16/33

"ig% 1%16; Setting &indo& of the bloc : S:7'E >$efault settings?

To ha!e a greater number of inputs you ha!e to specify the type, for

each of them, in the parameter 4input port sizes4% +n 414, as &e shall see later,

corresponds to an input of real scalar type%

"or each input here declared must then be specified the size of the a/es of the

graph by the parameters 4Gmin !ector4, 4Gma/ !ector4 and 49efresh period4,

that ha!e the same meanings of the bloc :S:7'E%

9eturning to our e/ample, connect to the inputs of the bloc

:8S:7'E the output signal from the superbloc and that coming from bloc

'97$:T =ust added, as sho&n in "ig% 1%20%

"ig% 1%20; Scheme comprising the superbloc of "ig% 1%1)%

1


17/33

#o&, running the command 4Simulate 3K 9un4, &ill appear t&o screens

of ScicosLab 5raphic; one &ith a single graphic related to the bloc :scope

inside the superbloc and one &ith t&o charts relati!e to the bloc :8S:7'E

=ust entered%

+s for the bloc :scope, also for bloc :8S:7'E is possible to

change the labels displayed on the chart a/es through the settings in the menu4Edit 3K "igures properties4, &ith the difference that no& the menu 4+/es4

present in the area 47b=ects bro&ser 4at the left are t&o%

#ote that, apart from a scale factor related to the different settings of the

ma/imum !alues sho&n on the a/es, the graph produced from the bloc

:S:7'E and the first of the bloc :8S:7'E are identical because they are

related to the same signal%

hen you ha!e comple/ schemes is ad!isable to associate at the points

of e/it and entry of the superblocs some identification labels of the signals

that ha!e to be connected, to do this open the superbloc and position on the

I*7 blocs I#Df and 7TDf, and by changing the parameter 4bloc properties3K Identification4 associate a label to the bloc input >or output? to the

superbloc% In our e/ample &e can associate the tag 4in4 to the input bloc and

4out4 at the output bloc, and the t&o patterns so modified finally appear as in

"ig% 1%21 "ig% 1% 22%

"ig% 1%21; Inner !ie& of the Supercloc created &ith the addiction of input and output label%

"ig% 1%22; $iagram of "ig% 1;20 after addition of labels of input and output from the superbloc %

1J


18/33


19/33

Tae, from the menu Sources t&o bloc :7#STDm and the bloc

:L7:HDc, then, from the menu Sin, for a change, the bloc +""I:QDm,

then from the menu Linear, tae the bloc S88+TI7# and from the menu

7thers the cited bloc :.L7:H)%

$ouble clic &ith the left mouse button on the blocs :7#STDm and

in the settings &indo& that &ill open set the !alue of the field 4:onstant4respecti!ely to ten and si/%

7pen the settings &indo& of the bloc bloc S88+TI7# and

change the !alue of the 4#umber of input of sign !ector >of 1, 31?4 from 4R1@

314 to 4R1@ 14 ; this field indicates the operation that must be performed to the

corresponding input; 4 14 indicates that the input should be added to the other

and 4314 &hich must be subtracted% +dding other 414 or 4314 you can add more

inputs to the bloc% The order in &hich they &ill appear in the graphical

interface of the bloc is the same, top to bottom, of ho& they are defined here

from left to right%

If the number of inputs are considerable and the input arro&s result too

close, you can Change the size of the block >as of any other bloc? by clicing&ith the right mouse button on it and selecting 4.loc 'roperties 3 K 9esize 4%

Lea!ing aside momentarily blocing :.L7:H), &e conclude the

description of the scheme saying that blocing +""I:QDm simply ser!es to

display the numeric !alue of the input recei!ed; for proof that &e are going to

do the default settings are fine, ho&e!er the ad!ice is al&ays to do se!eral

attempts &ith !arious options to see the effects and ho& they &or

independently; the practice teaches better than a thousand &ords% In place of

this bloc &e could use the bloc :scope already seen, and as it is a static

system &e could ha!e omitted the bloc :L7:HDc, ho&e!er &e mo!e for&ard

&ith &hat positioned and realize the scheme of "ig% 1%2)%

"ig% 1%2); .loc :.L7:H) e!aluation scheme%

#o& &e ha!e to enter the code in the bloc :.L7:H); to mae it open

its settings &indo&, &hich &ill appear as in "ig% 1%2

16


20/33

"ig% 1%2; Setting &indo& of bloc :.L7:H)%

The 4Simulation function4 indicates the name of the function that the

bloc &ill perform; the suggestion is to set the same name of the computational

function choice, in this case, such as 4SAuare4%

The 4Imput port sizes4 indicates the number and the size of the bloc

inputs; the message 41, 14 indicates that &e ha!e an input scalar type >1 1?%

"or e/ample, if &e &anted t&o inputs of the same type &e &ould ha!e tochange this !oice by &riting 4R1, 1, 1, 14

The field 4Imput port type4 indicates the type of input to the bloc; the

number 1 indicates, as already seen, a real input% e shall see later ho& the

data types are associated &ith these numbers in Scicos, for no& lea!e it so%

The items 47utput port size4 and 47utput port type4 indicate the same

things respecti!ely of the items 4input port type4 and 4input port size4, but

related to the outputs%

The items 4Input e!ent port sizes4 and 4output e!ent port sizes4 indicate

the number and type of inputs and outputs of e!ents to the bloc >the 4red

arro&s4?% In our case &e do not need them so &e can lea!e these fields blan%

The item 4Initial continuous state4 indicates, for blocs that contain aninternal state, the !alue that this must ha!e at the beginning of the simulation%

20


21/33

The item refers to the case of a continuos time type function, for blocs

containing discrete time type functions &e &ill use the field 4Initial discrete

state4%

The meaning of the rest of the items on the menu, along &ith all the

others, is a!ailable by clicing on the 4Qelp4 button at the bottom left of the

setting &indo&% The 4Qelp4 menu is a!ailable for almost all the blocs in thesame &ay; by selecting the Qelp button at the bottom of the setting &indo&%

:ontinuing &ith our e/ample, then, the only change that &e mae to the

default settings is to set the title of the function in 4SAuare4% >9eplace, in the

field 4Simulation function4 of "ig% 2), the name 4toto4 &ith 4SAuare4?%

SubseAuently it &ill open a &indo& titled 4: function4 containing the basic

template of the computational function of Scicos, appearing as sho&n in Tab%

1%2%

#include

void Square(scicos_block block!in" fla$% / ini" / if (fla == 4$ % / ou"&u" co'&u"a"ion / else if(fla == 1$ %

/ endin /

else if (fla == )$ %

Tab% 1%2; .asic structure of a Scicos bloc computational function in :%

The Scicos blocs defined &ith a computational function in : are based

on the same basic structure through &hich you can access all the information of

the bloc under e/amination; inputs, outputs, parameters and internal states%

This structure is defined in the file 4scicosDbloc)%h4 and this e/plain

&hy &e need to include this header in all of the computational function &ritten

in :%

$uring the simulation, the computational function is called &ith a flag

&hich corresponds to the tas to be e/ecuted% 7n the first e/ecution thefunction is called &ith flag ) that performs the procedures of initialization of

!ariables of the bloc >of the input, state and output? and then proceed &ith the

flag 1 &hich corresponds to the computation of outputs based on the !alues

of inputs and of the state%

In case &e ha!e also state !ariables, subseAuently to the flag 1, the

computational function &ill acti!ate the function corresponding to the flag 2

in &hich are updated state !ariables defined &ithin the bloc%

hen the simulation ends, or in case of an error that reAuires abortion

of the simulation, the last flag to be called is the that addresses the procedures

for releasing the internal memory for any !ariable declared in the initialization

phase%

Is possible to acti!ate also other flags related to other tass for specific

21


22/33

operation, but for this e/ample they does not interest us and since they are

referred to ad!anced functionality their e/planation is left to more specific

tutorial%

To realize the function that calculate the sAuare root of the imput the

computational function must be modified as sho&n in Tab% 1%(%

#include #include


23/33

initialize t&o pointers to double type !ariables that represent the input

and the output of our bloc, &ith &hich are associated by the macros

45et9ealIn'ort'trs >bloc, 1?4 and 45et9eal7ut'ort'trs >bloc, 1?4%

In Tab% 1%) there are some of the most commonly used macros to define

the inputs and outputs for the most common simple cases;

acro re"urn escri&"ion

*e",n-or"-"rs(block!5$

void +e"urns a &oin"er "o "hein&u" &or" 656 s&ecified.

*e"+eal,n-or"-"rs(block! 5$

double +e"urns a &oin"er "o "hereal &ar" of "he in&u" &or"656 s&ecified

*e",'a,n-or"-"rs(bl

ock! 5$

double +e"urns a &oin"er "o "he

i'ainar7 &ar" of "he in&u"&or" 656 s&ecified

*e"in"8,n-or"-"rs(block! 5$

char +e"urns a &oin"er "o "hecharac"er "7&ed in "hein&u" &or" 656 s&ecified


shor" +e"urns a &oin"er "o "heda"a "7&e shor" on "hein&u" &or" 656 s&ecified


lon +e"urns a &oin"er "o "heda"a "7&e lon &resen" on"he in&u" &or" 656

s&ecified

*e"uin"8,n-or"-"rs(block! 5$

unsinedchar

+e"urns a &oin"er "o "heda"a "7&e unsined char&resen" on "he in&u" &or"656 s&ecified

*e"uin"19,n-or"-"rs(block! 5$

unsinedshor"

+e"urns a &oin"er "o "heda"a "7&e unsined shor"&resen" on "he in&u" &or"656 s&ecified

*e"uin"32,n-or"-"rs(

block! 5$

unsined

lon

+e"urns a &oin"er "o "he

da"a "7&e unsined lon&resen" on "he in&u" &or"656 s&ecified

*e"u"-or"-"rs(block! 5$

void +e"urns a &oin"er "o "heou"&u" &or" 656 s&ecified

*e"+ealu"-or"-"rs(block! 5$

double +e"urns a &oin"er "o "hereal &ar" of "he ou"&u"&or" 656 s&ecified

*e",'au"-or"-"rs(block! 5$

double +e"urns a &oin"er "o "hei'ainar7 &ar" of "heou"&u" &or" 656 s&ecified

*e"in"8u"-or"-"rs(block! 5$

char +e"urns a &oin"er "o "hecharac"er &resen" on "he

2(


24/33

ou"&u" &or" 656 s&ecified


shor" +e"urns a &oin"er "o "heda"a "7&e shor" &resen" on"he ou"&u" &or" 656s&ecified


lon +e"urns a &oin"er "o "heda"a "7&e lon &resen" on"he ou"&u" &or" 656s&ecified

*e"uin"8u"-or"-"rs(block! 5$

unsinedchar

+e"urns a &oin"er "o "heda"a "7&e unsined char&resen" on "he ou"&u" &or"656 s&ecified


unsinedshor"

+e"urns a &oin"er "o "heda"a "7&e unsined shor"&resen" on "he ou"&u" &or"656 s&ecified


unsinedlon

+e"urns a &oin"er "o "heda"a "7&e unsined lon&resen" on "he ou"&u" &or"656 s&ecified

Tab% 1%); List of the most used macros to define inputs and outputs computational function &ritten in :%

To clarify the relationship bet&een the data type and the name of the

macro, as &ell as the interpretation of the data types used in ScicosLab, &e can

refer to Tab% 1% that associates each data type e/pressed in the Scilab language

the corresponding : data type as &ell as the number &ith &hich this isrepresented in the declaration of the inputs and outputs in the Scicos blocs%

Scilab : Scicos block

real double 1

co'&le5 double 2

in"32 lon 3

in"19 shor" 4

in"8 char )

uin"32 unsined lon 9

uin"19 unsined shor" ;

uin"8 unsined char 8

Tab% 1%; 8atches bet&een !ariables in Scilab language and : language%

#o& it should be clear &hy in the items 4Imput port type4 and 47utput

port type4 in the settings &indo& of the bloc :.L7:H) &e placed the

number 1; >"ig%1%2)? in this &ay the inputs to our bloc &ill be defined as

49eal 4, that correspond to the double type in :%

:ontinuing &ith the analysis of the code, in the body of the 4SAuare4function &e meets a flo& control based on the s&itch statement; &e ha!e

2)


25/33

already described the meaning of the acti!ation flags in a computational

function in Scicos, in these fields &e are going to &rite the code &hich in each

case &ill be gradually carried out by the function%

In our case the initialization =ust reset the output >flag )?, &hile for the

computation of the outputs >flag 1? arises in the output !alue of the sAuare

root of the inputs calculated &ith the sArt >? function%The use of a !ector for to access at the output port >as for the input? in

this case represents a refinement more conceptual than practical; ha!ing an

output of scalar type &e could also assign the output !ia the pointer to the

name of the same;

out sArt>in?@

In the generic case in &hich &e ha!e a !ector type output, ho&e!er,

because the name of a !ector represents a pointer to the first element of the

!ector itself, to access the !arious elements of the !ector &e should direct them

in the same manner as &e do &ith !ectors, as done abo!e%

Il flag risulta !uoto in Auanto per la funzione SAuare non occorre

eseguire alcuna operazione specifica al termine della simulazione%

The flag is blan because the function SAuare do not reAuire any

specific action at the end of the simulation% +fter checing the !alidity of the

computational function by the usage of the bloc :.L7:H), to add a ne&

bloc to Scicos is necessary to &rite the interfacing function of the bloc%

The interfacing function, as mentioned, is &ritten in Scilab language

and unfortunately there arenBt many tutorials on ho& to proceed; I do not deny

that many of the statements herein ha!e been identified by trial and therefore

may be sub=ect to error, in &hich case I as forgi!eness in ad!ance, hoping that

they are eAually useful%

Qo&e!er, as for the computational function, also the interfacing

function is based on a basic template structure to be edited from time to time

depending on the bloc; for my e/perience, the seleton of a basic interfacing

function is reported in Tab% 1% >already adapted to our function SAuare?

func"ion 05!7!"7&=Square(ob!ar1!ar2$5=07=0"7&=0

selec" obcase &lo" "hen s"andard_dra(ar1$case e"in&u"s "hen 05!7!"7&=s"andard_in&u"s(ar1$case e"ou"&u"s "hen 05!7!"7&=s"andard_ou"&u"s(ar1$case e"oriin "hen 05!7=s"andard_oriin(ar1$

case se" "hen

5=ar1

case define "hen

2


26/33


27/33

indicates that the interfacin! function created is referred to a Scicos

bloc &hose model is defined by the function 4scicosDmodel >?4 >as it &as

necessary to insert the directi!e 4#include 4

at the beginning of the computational function?

The line

%odelsi% = list ()Square), *$

indicates that the name of the co%putational function called by the

bloc >SI8ulation function? is 4SAuare4 and is &ritten in :, then the bloc &ill

be lined to a file 4SAuare%c4%

+s mentioned, the co%putational function can be &ritten in different

languages; for e/ample, if &e had &ritten a co%putational function in Scilab

language &e &ould ha!e to &rite this line as 4model%sim list >4 SAuare 4, ?4

The ro&s

%odelin = ["]

%odelout = ["]

%odelbloc+type = c

indicate that our bloc &ill ha!e only one input >If &e had t&o &e

should ha!e &ritten 4model%in R1@ 14? and a single output >same as for the

inputs? and that, again, the co%putational function is &ritten in :%

The line

%odeldep'ut = [- t- f]

ser!es to indicate to the interfacin! function the beha!ior of

computational function !ia t&o .oolean !ariables; deptDu >the first parameter?

and depDt%

If the !ariable depDu >W t? is set to true the bloc is al&ays acti!e, ie the

outputs depend also from the time >hich does not mean they necessarily ha!e

to changeC? hile the !ariable depDt, if true, indicates that the bloc It has at

least one output &hose !alue depend only on the input !alues >&ithout

depending from internal states or parameters?%

The line

!r'i = [txt = [ Square ]&& xstrin!b (ori! ("$, .ri!inal (#$, txt, s/ ("$,

s/ (#$, fill $&]

represent the graphical aspect of the bloc; the te/t and the position of

the same, the size of the font etc %%%

The line

exprs = list ($

2J


28/33

contains an array of strings representing the default !alues displayed in

the &indo& setting of the bloc in the fields used for to set the parameters of

the bloc; our bloc has no parameter to initialize so the list is empty%

The line

x = standard'define ([# #], %odel, exprs, !r'i$

create through a standard function of Scilab the real bloc defining the

size and lining the directi!es gi!en in the !arious cases pre!iously setted >the

parameters in the field 4model%4 defined in the case BdefineB, the &indo&

setting defined in case BsetB, the graphical interface of the 4grDi4 etc%? for the

bloc to be fully functional%

7nce our co%putational function has been tested and created its

interfacin! function, is necessary to sa!e them for compiling and lining them

in Scilab%

To do it open notepad and copy the code of the co%putational function,

sa!ing it as a : file in a default folder >or create a ne& dedicated folder? and do

the same for the interfacin! function sa!ing it as a 4%sci4 file >4SAuare%sci4?%

Then open Scilab and set the &or directory in the folder &here you sa!ed the

file abo!e >using the 4:hange directory4 command using the button sho&ing

the yello& folder in the toolbar belo& the Scilab menu, bet&een the &ords 4

'references 4and4 :ontrol 4, or by the command4 cd >BpathB? 4?

7nce you positioned the &oring directory in the right folder you must

compile and lin the co%putational function by typing the follo&ing command;

libn=ilib'for'lin+()Square), )Squareo), [], )c), )0a+elib)$&

This command reAuire fi!e parameters; the first, 4SAuare4, indicates the

name of the function to be lined in Scilab, the second, 4SAuare%o4, the name of

the ob=ect that &ill be created by the compiling process of our source code, the

third is a list of e/ternal libraries needed to create the ob=ect >none in this case,

thatBs &hy the list is empty?, the fourth indicates that the code to be lined is

&ritten in : language and the fifth is the name of the default maefile%

7nce the command is e/ecuted, in the default folder &ill be created

se!en ne& files, including a 4loader%sce4 file; this ha!e to be e/ecuted in Scilab

by typing

exec loadersce&

and, after, compile the interfacing function by typing

exec Squaresci&

2-


29/33

"ig% 1%2; :ompilation and linage of computational and interfacing function in ScicosLab * Scicos%

#o& open Scicos and select the 4+dd ne& bloc4 option a!ailable

under the 4Edit4 menu as in "ig% 1%2J%

"ig% 1%2J; 'ath to add a ne& bloc to Scicos%

26


30/33

In the &indo& that &ill appear >see "ig% 1%2-? insert 4SAuare4

and type 474

"ig% 1%2-;Selection of the name of the ne& bloc that ha!e to be added io the scheme

If e!erything is done correctly &e &ill see in the scheme this our ne&

bloc, &hich &ill appear as in "ig% 1%26%

(0


31/33

"ig% 1%26; The ne& bloc created placed in Scicos%

To test the ne& bloc created &ith the ne& interfacing function &e =ust

ha!e to create a test scheme; the result should be identical to that obtained &ith

the :.L7:H) containing the co%putational function pre!iously tested%

"ig% 1%(0; Scicos scheme containing the ne& bloc created%

If during our &or on Scicos, &e needed to get bac in ScicosLab to

change the &oring directory, or perform calculations, &e can do it &ithoutclosing the Scicos &indo& using the 4+cti!ate ScicosLab indo&4 command

(1


32/33

located under the 4Tools4 menu@ once you finished the &or on ScicosLab you

can return on Scicos typing 4Scicos >?@4 or !ia the menu 4+pplications4 of

ScicosLab >or, more simply, clicing again on the &indo& Scicos?

(2


33/33

1%( .ibliography

R1 TQESIS, Ing Lorenzo Lombardi, )1%ple%enta/ione di al!orit%i di

controllo della traiettoria e di co%unica/ione per un robot a controllo re%oto e

relative verifiche speri%entali4, ltrasound and #$T labs, uni!ersity of "lorence, Italy, 2011%

R2 Stephen L% :ampbell, Xean3'hilippe :hancelier, and 9amine #iouhah

)0odelin! and Si%ulation in Scilab2Scicos with Scicos3ab **) , second

edition, Springer%

R( 'hil Schmidt, )4reatin! a 4 5unction 6loc+ in Scicos) , tutorial online,

http;**&&&%scicos%org*Scicos:.locTutorial%pdf

R) Scicos Team, )4onstructin! new bloc+s in Scicos) , tutorial online,

http;**&&&%scicos%org*"ormationDscicosDmarsD200-%pdf

introduction to scicoslab-scicos

Documents