TCABR Data Aquisition System Update
A.N. Fagundes
, W.P. de Sa y
, and A.L.Dantas z
Instituteof Physis,UniversityofS~aoPaulo
R.Mat~ao,Trav R,187|CEP05508-900, S~aoPaulo,Brazil
Reeivedon3July,2001
Wedesribereent proposed updatesfor TCAqs[1 ℄, the TCABRdataaquisition system. Stable
and inregularuse,it shallbeenrihedinnewfutureforbetter performane. Reentaquisitions
widentheTCAqsapabilities inhardwareand software,inluding newVMEstationsandspeial
GPIBardsthatwillallowforthereationofloalinstrumentationnetwork.
I Introdution
TCAqs may be roughly divided in devies neessary
fordataaquisition;deviesontrolandoperationand
devies for data analysis. Aquisition and ontrol
de-viesstayinexperimentalroomandarebasedprimarily
uponVME[2℄instrumentationstandard.Personal
om-puters with hardware ation are also used. System is
shownin Fig. 1. Datainspetionandanalysisismade
in ontrolroombytheuseofPC-likeomputersusing
software,eitherfreelyavailableororiginallyinludedin
theomputerswhentheywerebought.
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DAT Tape
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Figure1. Computationaldeviesfordatafollowingand
sup-portofTCAqs. Computersinovalareloatedin
experimen-talroom, onnetedby optialbertoontrol room. The
upperline suggests that, in its nal version, TCAqs will
haveontrolledaessthrougharewall. Dataandpubli
servieswillbeavailableinaserverbeforetherewall.
The development of software has been done in a
slow pae, for it ats on elements onneted in a
lo-al network, inluding the omputer in experimental
roomthathousesthetriggerboardthatrestheentire
TCABRplasmashot. Thisposessafetyissues,thathas
been solved in the safest way: The loal network has
onlyoneuser,thetehniianinhargeofTCABRdaily
tasks,whenthemahine isin sientioperation.
II Present apabilities.
TCAqsisbasedupontheVME[2℄withoneratewhih
has21slotsavailable. Table1desribesavailable
mod-ules.
TCAqs ontrol ation is limited to prodution of
lightpulsesforringtheinterveningproessesthat
on-stitutesthetokamakationandproperreording
inter-val. Severalsideations,likesoundandlightwarnings
thatpreedestokamakshotsaredonemanuallybythe
operator, inluding theneessary ationof powerline
reservationthatfeedsmaintransformerfortoroidal
ur-rent. As for data aquisition, 18 ADCs modules are
available,ofwhihabout10areinusepermanent,
gen-eratingaround1:3MB ofdata(ompressed)per shot,
originatedbyaround40souresofdiagnostis. Table2
summarizesobserveddiagnostis. Theoperational
rou-tine forprogrammingthe TCAqsinvolvesdiret
writ-ing of onguration les, that are onveyedto proper
hardwarehousingomputer.
TCABR inherited CAMAC systems, omprising
rates and ADCs from TBR [5℄, the former tokamak
atthePhysisInstitute. Theseresouresarenotinfull
useforthelakofhardwareandsoftwaresuport.
fagundesif.usp.br
y
piresif.usp.br
Qt Unit Fun STD Chan Mem Res Sp.Rate
(kb) (bits) (ksp/s)
1 Crate vme
2 Crate vme Upg
1 68060 Cont vme
2 68040 Cont vme Upg
3 Pulse gen trig vme 16
1 Pulse gen trig vme 16 Upg
18 ADC wfr vme 8 512 12 1300
9 ADC wfr vme 8 512 12 3000 Upg
4 Crate am Upg
2 ADC wfr am 2 64 10 2000 Upg
6 ADC wfr am 8 4 8 4000 Upg
2 ADC wfr am 4 8 10 2000 Upg
2 ADC wfr am 32 1 10 5 Upg
Table1. TCAqshardwarefordataaquisition. \Upg"standsforupgrading, meaningthat itistobeavailable ina
shortperiodoftime.
Diagnosti Soure Num.Points Timeinterval
(1000) (ms)
VertialCurrent 2 50 100
PlasmaCurrent 1 50 100
LoopVoltage 1 50 100
OHTurrent 1 50 100
Sineoil 1 50 100
HorizontalPosition 1 50 100
X-Ray 3 50 100
SoftX-Ray 2 50 100
B
T
1 50 100
B
Z
1 50 100
H
12 50 100
MirnovCoil 1 50 100
FluxCoil 1 50 100
Diamagnetioil 1 50 100
Bolometer 1 50 100
LangmuirProbes 4 50 100
Interferometer 6 60 100
CommandVoltage 1 50 100
GasPuÆngVoltage 1 50 100
ECE 1 50 100
Table2. Normallyreordedsignalsin TCABRinjuneof2001
III Upgrading
The TCAqswill experimentasigniantexpansionin
the near future. Two more VME stations, with
Mo-torola68040CPUbasedontrollersareexpetedto
ar-rive in few weeks, together with 9 moreADCs of the
erator. Oneof themwillsupplyregistrationmeansfor
about 100 Mirnov and the other is to be installed in
ontrol room for software development, removing the
present day safety risks of tampering with the rate
usedforringthemahine.
boards will allow for the reation of a
instrumenta-tion network in experimental room, overlooked by a
omputer and a smooth link with TCAqs. Among
other andidate devies that may be present, like
os-illosopes, voltages meters. et. all CAMAC
instru-mentationresoureswillrenderavailable.
IV Data ompression
Daily use has determined that signals are to be
sam-pled with intervals of 4s in a extension of 50000
points,overing200msoftime. 12-bitresolutionADCs
produe numbersin theintervalfrom 0to 4096(2 12
).
Eah point demands twobytes for expression.
There-fore,eahsoureofdiagnostisgenerates100kbofdata
pershot. A single ADC astheones presentlyused in
TCAqs, may produe 0:8Mb of useful data (4Mb if
used with full memoryapaity). 5Mb ofdata are
tobekeptasthetotalinformationaquiredintheshot.
Obviouslythisnumberisexpetedtogrowasdierents
souresofsignalsareaggregatedintothedata
aquisi-tionsystem.
Forsakeofreduingtransmissionerrors,inrease
ef-ienyin storageand providefasteraesstime,data
has to be ompressed in order to obtain more easily
manageablevolumes. Unfortunately,dataompression
is notawell dened issue withpresribed reipesand
isstrongly dependent upon thekindofinformation at
hand. The theme is studied in several books, two of
whiharewrittenbyK.Saywood[10℄andM.Nelsonand
J.P.Gailly [8℄. In Data Compression, twomain
dire-tions are generally pursued: lossy methods and
loss-less methods. The former produing usually the best
results in ompression, at the sarie of information
onretrieval. Lossymethodswerenotonsidered. From
availablemethodsonlylosslessoneswerehosenforthe
TCAqs. Thatmeansthatinformationrestorestoits
en-tiretyafter deompressionwithnodierenesbetween
thereonstrutedlesandtheoriginal.
ThebookbyM.NelsonandJ.P.Gaillydesribes
sev-eral ompressionmethods making omparisonsamong
dierent methods a easy task. But in our study also
otherpromisingpublished methodsweretried.
The methods hosen were: Humann,
Adpta-tive Humann (AdHu), Arithmeti (Arith),
Statis-tial Modelling (ArithN), Lempel-Ziv-Welh method
(lzw15M)andDynami MarkovChain(dm)(as
pub-lished in[9℄. Atest set ofdatawasprepared,madeof
27lesasobtainedfromTCAqsAnalog-to-Digital
on-verterdevies, plusa le ontaining expressed with
100000 gures. Test set had size 5:34Mb,
ompara-ble the present TCAqs load. To ompare results we
adopted the Compression Index dened aording to
[7℄,as
CI =
1
Compressed size
100 (1)
The worse ompression method would produe a le
ompressed with size equal to the original size and a
CI =0%.Onotherhand,anidealompressionsheme
wouldhaveale withompressedsizeofzerosizeand
CI =100%. Resultsaresummarizedin table3.
All methods onsideredredue originalles to less
the half of the size and would be of signiative
im-provementin datamanagement. Thebest method
ap-pliableorrespondsto statisalmodelling, in whih a
ompressedsizeof1;02 Mbwasobtained,orresponding
to 81% ofdata ompressionin 103seonds. Time has
to beonsidered, asideCI. So,the ditionary method
baseduponLempel-Ziv-Welh(usuallyknownasLZW)
washosen. Aleof1:2Mbfortheoriginal5:34Mbwas
produed in 47swith a CI =77%. This means that
les produed by data aquisition devies had around
one-fth of their original size on the average,without
nolossesinontents.
Althoughwith good perspetives,weworkedupon
theodefornetuningitforourspeiuse. The
orig-inalodebyMr.M.Nelsonwasdonewithawidehorizon
in mindaiming theompressionof writtentext, being
appliable to a universe of 256 haraters, for
opera-tional systems of 16 and 32 bits. In TCAqs ase, we
dealwith dierentOSsbut allof thembasedupon32
bitandonly12possibledierentbitsmayour. With
this boundary onditions, the ode for LZW method
was modied to aept only 32 bits OSs, The nal
produtisashorterode,runningfasterandshallpose
no problems as long as ADCs with resolution less or
equal 16 (meaning systems able to resolve 1 part in
2 16
=64;536)areused. Thedrawbakisthat wehave
auniquewayofompression,insteadofaknown
stan-dard, making harderinformation exhange among
re-searhenters. An attenuantfator is that ode
om-pilesinopensoftwareode,withwidelyavailableGCC
ompiler and will be freely available | as also is the
ase with data aquired | from TCABR laboratory
omputers.
Method R.File CI Time
(b) (%) (s)
AdHu 1885495 65 18
Arith 1914252 64 25
ArithN 1017800 81 103
lzw15M 1206563 77 16
dm 1345600 75 121
Human 1948709 64 47
Table 3. Results of ompression aordding dierent
tehniques. The same set of data was applied to
ev-ery method, involvina a seleted olletion of atual
datafromTCABR29souresofdiagnostispluswith
100kgures,summingup5.34Mb. "R.File"standsfor
ResultingFile and\CI" standsfor Compression Index
Read board address
Request permission
for
reading and writing
Read byte
Write byte
Returns
for new action
11110000 (=0xf0)
10011011(=0x9b)
External actions
Figure 2. Board PDL-IO-16C has a simple programming
yle. We requestpermission from operational system for
reading/writing onthe boardaddress. Abyteis formedof
bits, eah one assuming only \1" or \0" values that will
lose or keep open orresponding relay in assoiate relay
board. Intheexample,therst,2 nd
,4 th
,5 th
and8 th
relays
would be atuated whenwe write 0x9bonboard address.
Reading ationis done by negating byteread: theanswer
of0xf0impliesthattherstfourrelays(fromrighttoleft)
areatuated.
V Use of relay board
Development of open software ontrolled hardware is
in progress. Initially, it is foreseen the operation of a
boardabletoonveyaword(twobytes)totheexternal
world. This board links to another one, through
op-tial deoupling, whixh has eight independent relays.
The internal board is identied PLD-IO-16C; the
ex-ternal board, PD-INTF8, both made by the brazilian
ompany PRODELS[6℄. The internal board has two
input andoutput independent ports, with8bits eah.
In order to aess the ports, two bytes are neessary,
although only one is in use. The board base address
maybeonguredthroughadipswithnamedSW1in
forbothreadingandwritingbytheuseofaontrolbit.
Theboard hasasimpleprogrammingyle, asshown
in Fig. 2. All software was developed in Clanguage,
with GCC ompiler, using funtions ioperm, inb and
outbunderlinuxoperationalsystem.
Thiswillmakepossibletoputunderautomati
on-trolsomeofthe ationsneessaryto retheTCABR,
inludingpowerlinereserveandwarninglights,asmay
help in operatingtransientation in the side ontrols
andsafetysystems,likedetetingunexpetedlive
pres-ene in forbidden areasorunmet onditions for
toko-makshot.
VI Conlusions
Stableanddependable, havingalready reordedafew
thousandsshots,theTCAqsisabouttohavea
signi-antinreaseof potentiality, beoming morepowerfull
andversatile. Addinginomplexity,thenewhardware
willinreaseeitherdiretly theapaityofobservation
and registry of physial phenomena; asindiretly,
al-lowingforthe reationof adediatedinstrumentation
network aroundtheTCABR. Softwareforbetter
om-pressionandalsoforhardwareationunderopensoure
software has been developed and is still in progress,
pursuingahigher levelof automatism in asafer
envi-ronmentforoperatingTCABR.
Referenes
[1℄ A.N.Fagundes,W.P.deS,P.M.S.A.Coelho,Fusion
En-gineering andDesign,48,213(2000).
[2℄ http://www.vita.om
[3℄ http://www.miroware.om
[4℄ http://www.tx.se
[5℄ A.Fagundes,Rev.Fis.Apl.Instrum.8,42(1993).
[6℄ www.prodels.om.br
[7℄ K.Loudon, Mastering Algorithms with C, O'Reilly &
assoiates, In.1999
[8℄ M.Nelson,J.L.GaillyTheDataCompressionBook.2 nd
Ed.M&TBooks,1996
[9℄ T.L.Yu,Dr.Dobbsjournal (243)1996.
[10℄ K.SayoodIntrodution to DataCompression, 2 nd
Ed.
