Fredian, T.W.

Klare, K.A.

Manduchi, G.

Stillerman, J.A.

DSpace@MIT

PFC/JA-96-22MDSplus Data Acquisition SystemJ.A. Stillerman, T.W. Fredian, K.A. Klare1, G. Manduchi 2June 19961Los Alamos National Laboratory, Los Alamos, NM 87545.2 CNR, Padua, Italy.Submitted to Review of Scientific Instruments.This work was supported by the U. S. Department of Energy Contract No. DE-AC02-78ET51013. Reproduction, translation, publication, use and disposal, in whole or in partby or for the United States government is permitted.MDSplus Data Acquisition SystemJ.A. Stillerman, T.W. Fredian MIT Plasma Fusion Center; K.A.Klare Los Alamos National Lab; G. Manduchi CNR, Padua, Italy.MDSplus a tree based, distributed data acquisition system, wasdeveloped in collaboration with the ZTH Group at Los AlamosNational Lab and the RFX Group at CNR in Padua, Italy and iscurrently in use at MIT, RFX in Padua, TCV at EPFL in Lausanne,and KBSI in South Korea.MDSplus is made up of a set of X/motif based tools for dataacquisition and display, as well as diagnostic configuration andmanagement. It is based on a hierarchical experiment descriptionwhich completely describes the data acquisition and analysistasks and contains the results from these operations. Thesetools were designed to operate in a distributed, client/serverenvironment with multiple concurrent readers and writers to thedata store. While usually used over a Local Area Network, thesetools can be used over the Internet to provide access for remotediagnosticians and even machine operators. An interface to arelational database is provided for storage and management ofprocessed data. IDL1 is used as the primary data analysis andvisualization tool.IntroductionMDSplus provides a set of tools for performing data acquisitionand analysis for pulsed experiments. It is designed to keep allexperimental data, analysis results, experiment configuration andsetup information together in an organized fashion. The data foreach pulse of the experiment is stored in a hierarchical treestructure much like a file system. This experiment model, enablesthe users to organize very large data sets. Some of the MDSplusdocumentation is available on the Plasma Fusion Center WWW pagesat http://cmod2.pfc.mit . edu/mds/mdsplus .html.Data StorageAll of the information about each instance of the experiment, orpulse is stored in a hierarchical structure which is accessibleto the whole group of researchers. This comprehensive and openapproach both enables and encourages collaboration among thescientists. Since all of the information is stored in oneplace, it is easy to keep track of exactly what was done. Thehierarchy provides organization for all of these pieces ofinformation. This becomes critical as the number of data itemsgrows; the CMOD experiment currently has more than 30K nodes inits hierarchy.2 Since all of these items are stored in the sameway, one set of tools can be used to manipulate both setupinformation and results from the experiment.After data acquisition for a pulse is completed the tree for thatshot contains:Presented at 11t" Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 1* The setup information for Diagnostics* Calibration and geometry information* The setup information for Data Acquisition* The machine control settingso Task scheduling* The raw data from engineering systems and diagnostics* The processed dataPaths, Members and ChildrenMDSplus trees contain two types of nodes, 'children' and'members'. Children or branch nodes are used to define thestructure of the tree. These nodes can not contain any data.They are analogous to directory files in a computer file system.The second kind of nodes, called members, actually contain thedata. They are analogous to the files in a computer file system.These members, may also have members and children below them aswell as containing data.A node in a tree can be referred to by either an absolute orrelative path. Absolute paths begin with a tag referencefollowed by a series of branch specifiers. A typical absolutepath \cmod: :top. engineering. ohl: volt contains a tag \cmod::topfollowed by a list of branches separated by dots.engineering.ohl followed by a leaf reference delimited by acolon :volt. Relative paths are relative to some current defaultlocation. If the current default is \cmod::top.engineering.ohlthe above node could be referred to simply as volt and\cmod::top.engineering.oh2:volt could be referred to as.-. oh2:volt.Data typesIn addition to a wide selection of primitive data types (byte,word, long, float, double, complex, etc...) MDSplus supportscomplex types to store commonly used combinations of items.* Signal - used to associate independent axes with arrays. Theyconsist of result data, raw data and one or more descriptionsof axes. Subscripting can be done on either the independentparameters or the array indices.* Units - can be associated with any node in the hierarchy, orwith any term of a complex data item. For example, adigitizer channel would have Volts, Counts, and Secondsassociated with its' processed, raw, and first dimensionparts.* Range - composed of a start, and end, and an increment. Theyare used in the descriptions of clocks. Multi-frequencyclocks are described by ranges in which the terms are arrays.* Dispatch - stores a description of when a task should beperformed and which server should perform it.* Task - stores a description of something to be done. Forexample, a task could say to perform an ABM operation on adigitizer or to SUBMIT a particular batch job.Presented at 11th Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 2* Action - used to describe automatic data acquisition andanalysis activities. They are made up of a dispatch and atask.* Expressions - Any node in a tree, or any term in the abovecomplex types can contain an expression instead of a primitivedata object. These expressions are evaluated by the built-inexpression evaluator when the node is referenced. This is thesame expression evaluator, called TDI, which is described inthe Data Analysis section of this paper.Trees and SubtreesA tree can be made up of a set of subtrees which are each storedin their own set of files. When a hierarchy is opened all ofits subtrees are automatically opened, making it appear as oneintegrated tree.The individual subtrees can also be accessed independently fromthe rest of the hierarchy. This means that one does not have torestore an entire 80 Mbyte shot from the data archive system inorder to look at one or two traces. Using this subtreemechanism, write (or read) access to a subset of the tree can berestricted to an authorized group of users.Editing vs. TraversingEach node in the tree has three kinds of information associatedwith it. There are a set of read-only attributes including itsname, any tag names associated with it, and its location in thehierarchy; a set of fixed length read-write attributes such asowner, date written, data type, data length, location in datafile; and, if there is data associated with the node, a variablelength record which contains the actual data. When a tree isaccessed it can be opened in two ways. Normally, it is opened'not for edit' which gives read-only access to the structure ofthe tree and read-write access to the data. In order to makestructural changes to the tree, adding or removing nodes,renaming nodes, etc... the tree must be opened for 'edit' . In thenormal mode, multiple concurrent readers and writers from allcomputers in the cluster are supported. Only one user can edit atree at a time. For this reason 'editing' changes, as opposed to'value' changes are normally done off line.Two tools are provided for viewing and manipulating the trees.The TRAVERSER is an XWindows / Motif based application forbrowsing the hierarchy. TCL, or Tree Command Language, is acommand interpreter with commands like 'directory', 'setdefault', 'put', 'show data' etc... See Figure 1 for a typicalTRAVERSER screen.Presented at ll Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 3F.... E....... C s . -om zH pFile 4: dii Data Customize Help-.:TOP ..SADMINWEDGE...* ELECTRONS ...] ENGINEERING9 CRYO ... iZ POWERSYSTEM.# :FIZZDETECT:TESTBUS DIAG...CAMAC isplay Data* :CLOSE SHOT ...# :DIG FREG Display Nci*JUL 'g Ile "- Modify Data j# : J221 STARTMHZ CLOCK: TSTART Setup DeviceALTERNATOR ... Do ActionBUSHV ... Toggle OniOffa BUSLV ... ............A12_1 ... _2pen: DDECODER. :Close14 :INCAA1.. L8212_ . Quit:1- 3 : ... L.... 2 ....... ... ...... _ _Figure 1 TraverserFrom within the TRAVERSER, when 'modify data' is selected a datamodifier appropriate to the data type of the node is displayed.Figure 2 shows a typical data modifier screen for a nodecontaining a simple expression.r~ On!Off M~ Panmt \BTORTags: - - TI CT.Expression Units: tesakMAGHARDWARE:TRAQ_3:T2812 06:INPUT 7.1*1. 1.367* (.761 1 .66):k Appy Reset CancelFigure 2 Expression ModifierPresented at i1t1 Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 4Data AcquisitionThe MDSplus data acquisition cycle is driven by the actiondescriptions stored in the experiment model. These actions tellthe dispatcher what tasks should be done by which servers and inwhat order. After the cycle completes, a complete record of whatwas done is stored back into the model along with the data fromthe experiment.MDSplus currently supports more than 60 different dataacquisition device types. New diagnostics composed of these canbe added to the experiment model in just a few minutes using theTRAVERSER.Adding support for new types of data acquisition hardware usuallytakes only one or two days of effort depending on how complicatedthe device is. One routine needs to be written for eachoperation the device will support, and a setup form needs to beassembled. Stubs for the routines are generated automatically bythe GEN DEVICE utility. A typical ADC requires INIT, TRIGGER,and STORE operations. The user interface can usually beimplemented without any code, using the special widget setdeveloped for this purpose and a graphical GUI builder.Dispatcher/ServerThe tasks which make up the data acquisition cycle are managed bythe DISPATCHER. This application is an interpreter with a set ofverbs for constructing pulse files, collecting together actions,and overseeing their execution by SERVER processes. It isimplemented using the generic MDSDCL interpreter. DECNET is usedfor all inter-process communications.Actions in the tree are scheduled by a phase and sequence number.An installation specific state machine causes the DISPATCHER toexecute each phase of the shot cycle in turn. 2 A typical shotcycle might look like:" INIT" copy model to pulse, and open it." extract all actions from pulse into dispatch table." dispatch all initialization operations, and wait forcompletion" PULSE* fire high speed timing system* STORE* dispatch all store operations* dispatch all analysis operations* dispatch 'close' to all serversTraverser for Device SetupThe TRAVERSER, described above, is used to add diagnostics to thehierarchy and to configure existing devices. The setup form fora typical CAMAC module can be seen in Figure 3.Presented at 11 Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 511 - - s mW* I. ..*. . 1 1 -CAMAC name: PComment:Mode: Burst.Frequency Trigger1 MHz500 KHz1 MHz ..1int Action V r Store ctonO Apply! Reseti CancelFigure 3 Programable Clock SetupIDL for Custom Data Acquisition and ControlCustom interfaces to the experiment model are implemented in IDL.The user of a diagnostic may wish to specify their settings in adifferent way than they are stored in the experiment model. Itis very easy, using the IDL widget and MDSplus interfaces, toput together a screen tailored to the task at hand. These rangefrom fairly simple screens where the user sets their digitizingparameters (start time, rate, number of samples) to PCS which isused for plasma shaping and parameter control.Data AnalysisAll of the interfaces to data in MDSplus are based on anexpression evaluator called TDI. TDI expressions can be used inuser analysis programs in C, FORTRAN, or IDL, interactiveanalysis and display programs like the SCOPE and are used toimplement various aspects of device and shot cycle support.Programming InterfaceThe IDL and compiled language interfaces to MDSplus data consistof four routines.1. MDS$OPEN , experiment-name, shot-number2. MDS$CLOSE [, experiment-name, shot-number]3. MDS$VALUE, expression [, arguments]4. MDS$PUT, node, expression [, arguments]Given these four a user has complete read and write access to anMDSplus data store. The optional arguments to MDS$VALUE andMDS$PUT are values to be substituted into the expression when itis written to the tree. For example, given an array of datacalled values one could put an expression containing it in a nodecalled temperature as follows:Presented at 11 kt Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 6MDS$PUT, 'TEMPERATURE', '$*1.76+1E4', valuesOne argument is substituted for each '$' found in the expression.TDI transparently operates on arrays as well as scalars, and doesautomatic conversion to compatible data types. It includescontrol structures, function declarations, assignment operatorsand hundreds of built-in operations.See http://cmod2.pfc.mit.edu/help/@mdsplus/tdishr for a completedescription of its' functionalityDWSCOPEThe DWSCOPE is an XWindows-motif based data display application.Each DWSCOPE can display up to sixty-four traces in four columns.These panels can be updated automatically during the shot cyclewhen new data becomes available. For each panel the userspecifies expressions for the X and Y axes and various displayparameters. These DWSCOPE panels can be cut and pasted betweenDWSCOPEs. Figure 4 shows a simple DWSCOPE display. The mouse isused to zoom, pan, and point in the display.File Pointer Mode Print CustomizeUpdates Autoscale H00- ----- - Setup data sourceCori - .................... .. .. . .. . .. . .. . ....... AutoscaleAutoscale Yv -ur- 6-- 25 Autoscale All -Autoscale All VAll same scalev Z Centroid S6O11 All same X scaleAll same X scale (auto Y)-. . . All same Y scale -0;5 Reset scalesL T o1il".Reset all scalesRefresh09 -- ---- 9 PrintPoint < Zoom " Pan , Copy UpdatesI6112O25 AppIfFigure 4 DWSCOPE DisplayPresented at 11 Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 7IDL (Research Systems Inc.)IDL is a commercial data analysis and visualization package.MDSplus provides the interface to data described above and an SQLinterface to get and put records to RDB relational databases.It has become the standard tool for data analysis and displayapplications in MDSplus.IDL procedures are invoked from batch jobs during the shot cycleto automatically process raw experiment data and store analyzeddata back into the tree. Figure 5 displays a typical automaticanalysis routine. IDL's automatic vector arithmetic makes the computation of poh easyto express.;procedure to calculate oh powerpro poh, shot,poh,t;open the analysis tree, get efit datamds$open, 'analysis' , shotli = mds$value (' \efit aeqdsk:ali')majr = mds$value ('\efit aeqdsk:rmagx')ip = mds$value ('\efit aeqdsk:pasmat')psibry - mds$value('\efit ssibry')t=mds$value ('dim of (\efit-geqdsk:pcurrt, 2)')vs =6.283*deriv (T,psibry) ;surface voltage1 = 6.283*majr*li*l.e-9 ;plasma inductancevi - 1*deriv(t,ip) ;inductive voltagevres = vs - vi ;resistive voltagepoh - ip*vres;put results back into tree and close filemds$put, '\analysis: :top.results:poh' ,$'buildsignal($,*,$)',poh,tmds$closereturnendFigure 5 Sample data analysis routineWLOGBOOK is an IDL application for accessing the electroniclogbook implemented in RDB . It also provides a general interfaceto tables in relational databases. Each site augments thetables which make up the logbook part of the database with tableswhich are relevant to their particular needs.IDL is used to implement many site specific applications havingto do with the data system. At CMOD, it is used for everythingfrom playing the automatic audio announcements during the shotcycle to controlling the main plasma parameters for the machine.ConclusionMDSplus is currently in use at fusion sites in the US, Italy,Switzerland, and South Korea. Over its five years of operation,it has evolved with the available computer technology and theneeds of its users. It has proven itself an effective tool fordata acquisition, analysis and management. This system could nothave been developed without the help and encouragement of theresearch groups at the collaborators sites.IDL is a registered trademark or Research Systems Inc.T. Fredian, J. Stillerman, M. Greewald, Data AcquisitionSystem For Alcator CMOD, This conference.Presented at 11t" Topical Conference on High-Temperature PlasmaDiagnostics, May 12-16 1996Page 8S. Horne, M. Greenwald, I. Hutchinson, S. Wolfe,G. Tinios, T. Fredian, J. Stillerman, Performance of theC-Mod Shape Control System, Proceedings of the IEEE 15 tSymposium on Fusion Engineering, 782-785 (1993)Oracle RDB registered trademark of Oracle CorporationPresented at 11th Topical Conference on High-TemperaturePlasma Diagnostics, May 12-16 1996 Page 9

MDS plus data acquisition system

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MDS plus data acquisition system

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