Laeger, H

Martini, R

Ninin, P

Pfirsch, E

Sollander, P

CERN Document Server

ST/Div. Rep. OCR OutputGeneva, 25 October 1995Chicago, LISA, October 30-November 3, 1995International Conference on Accelerator and Large Experimental Physics Control SystemsPresented at ICALEPCS' 95the experience gained and the problems encountered as well as the evolution of the system.and the integration of the system in the existing control environment. An account is given ofthe interface tools for data management and data display, the data-acquisition mechanism,This paper gives a description of the data-logging system, including the database structure,year, after which they are automatically archived.one to fifteen minutes; data are kept online for periods varying between one month and oneinterruption. Currently, around one thousand measurements are logged at rates ranging fromOne of these requirements is the need for data—logging throughout the year without anysome particular features had to be implemented to meet specific requirements of the TCR.Hardware and some software are common to the SPS / LEP accelerator control system, thoughused for over two years by the Technical Control Room (TCR) and by equipment groups.A data logging system for the technical infrastructure of CERN was developed and has beenAbstractR. Martini, H. Laeger, P. Ninin, E. Pfirsch, P. SollanderData Logging for Technical Services at CERNCERN-ST-95-03 — . `mmmmmm““m”“’CERN LIBRARIES, GENEVACERN - ST DIVISIONEuropean Laboratory for Particle PhysicsL l, EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCHdata storage OCR OutputThe product was broken down into the following components:2.2 Product Componentscan be data-driven. The data logging application conforms to this policy.ity in an ORACLE reference database (known as STRefDB), so that control system applicationsThe TCR has a policy to hold all elements of the surveyed equipment under its responsibilworkstation to obtain data from the equipment were used in the data logging application.type of equipment being treated. The standard communication modules which allow users at ablies (PCAs) connected to the control network. Data is accessed differently depending on thement Control Assemblies (ECAs) connecting the equipment, linked to Process Control AssemThe measurements to be logged are all on the control network [2] which consists of EquipThe table structure defined for this project was used in the TCR logging system.is an ORACLE-based solution, implemented for storing key measurements for LEP operations.The design of the product was heavily influenced by the LEP logging system [l], which2.1 Design Constraintsproblems should be reported to TCR operators for remedial action.data should be logged without interruptionbe kept if requiredsummary data (averages, maximum and minimum values within a period of time) shouldlogged data should be available for display in graphical or in raw formadding new measurements should be possible by non-specialistslogging parameters should be changeable at any time by non-specialistsdata should be archivedmonths)data for different measurements should be kept online for different periods (days todifferent measurements should be logged at different frequencies (1 to 30 minutes)The TCR required the following basic functionality from the data-logging system:REQUIREMENTS, CONSTRAINTS, DESIGN CRITEREAwas undertaken to devise a solution that would share as many resources as possible [1].number of measurements relevant to the performance of the LEP accelerator. A gqllaborationThe start of this project coincided with a project in the SL control group to log a largethe existing control system.ments that required logging, a computer—based system was envisaged which could be linked toor to reduce cost, e. g. energy consumption. In order to respond to a growing number of measureto analyse the behaviour of equipment prior to malfunction, to help in optimizing performance,to trivial capses such as lack of paper or ink. Logged data was becoming increasingly necessaryrecorded on paper. These devices were expensive to maintain, and could be n0n—operational dueFor many years, a number of measurements, mainly electrical and iluid data, had been365 days a year, and takes corrective actions where needed.the Technical Control Room (TCR) monitors the state of this infrastructure 24 hours a day andsafety systems such as fire and gas detection. To ensure the smooth running of these servicesThese services include electricity supply, water supply, heating and ventilation, and personalof a medium—sized town, is required to run the accelerators as well as all other activities at CERN.A complex infrastructure 0f basic technical services, comparable to the industrial serviceslogging programs. OCR Outputhas been developed to handle data validation, program malfunction, or communication with themodification of logging parameters. These scripts are run by the data-logging specialist as no toolscripts has been developed in order to allow for the creation of a new logging group and for thefore not described in the STRetl)B, the previous facility cannot be applied. For these, a set ofFor measurements that are managed by services other than the TCR and which are thereand modification handler that a change has been requested.logging database is then updated with the logging group number in order to inform the creationlar way modifications to a logging group’s parameters can be made. A designated table on thechoosing measurements from the reference database on a form-based user-interface. In a simiand to set the logging parameters according to their needs. A logging group can be created byThis enables users of the data-logging system to specify the measurements to be logged3.2 Data Managementfor time slot management data, where x is the logging group identifier.used: Tx-LOG for logged data, Tx-TIME-SLOTS for time slot data, and Tx—TIME_MANmany sets of tables as there are logging groups. A strict naming structure of the tables islogged data, one for the time stamp, and one for the time slot management. There are asA set of tables is used to store data for a logging group; this consists of one table forat data correlation.time stamps and measurement values [1]. This strategy was adopted to facilitate future attemptsfor each group of measurements read, whose corresponding rows are updated sequentially withused, was that devised by the above group, i.e. the use of a set number of pre-filled time slotsysis done by the SL control group. The structure of the tables, as well as the storage methodAn ORACLE database was chosen as the repository for all logged data, following the anal3.1 Data Storage3 PRODUCT DESCRIPTIONon any X-terminal that can connect to the control network.programs, written in C and Pro*C run on an HP-UX workstation. The user interfaces may runThe database is currently running on a SUN SPARC 2000 station, the logging and archive2.4 Environmentlong.where they are presented according to the equipment systems and subsystems to which they benumber. This organization of data is transparent to the user selecting measurements for display,(logging period, retention time, start and end dates). Logging groups are identified by a uniqueLEP tunnel. All measurements within a logging group have, by definition, the same parameterslar measurements to be logged in a similar way, such as humidity from different regions of theData lcgging is bascd 0n thc concept of logging groups which cover a number of simi2.3 Conceptdata display.archivingdata accessdata mzmagcmcm(Fig. 3). OCR Outputthe data is written to the tile system, it will be written to the database once the latter is availableonce again by consulting the control tables. Should access to the database become impossible,will then determine which data elements to access and where the data will be stored; this is donement it will be accessing since data from different sources are read and interpreted differently. Itcontrol tables. Once a black box program has started, it must first determine what kind of equipIn order to determine how many logging black boxes to run, the server program reads the loggingFIGURE l: Checks on the logging server program FIGURE 2: Server checks on logging processespresent ProcessingOI llsquipl Pmcssscheck presence other- absentpresentOperererconnection fileabsenr men TCRcreate databasepresentconnection filedatabase connection filetest presence ot absent Idelete databaspresentil@——i kill Serverserver check file / presenttest presence ofabsent start logging ·presentprocessingSS"/BrOther I I I processesabsent |start loggingof loggingtest existencepemdOf Ioggmg ServeWarr sercheck presenceserver which then monitors their behaviour (Figs. 1 and 2). This server must always be running.instance of this program is run for each logging group. These programs are launched by a loggingused to read any type of equipment whose access method has previously been determined. Onefor storing them in the database. There exists only one program, the logging black box, which isThis component is responsible for obtaining the measurement values from their source, and3.3 Data Accesseach logging group. Any errors in the table manipulations are signalled and can be recovered.contains the parameters (physical address, conversion factor) relating to the measurements incontrol tables, one which holds the parameters relating to the logging groups, the other whichdata access programs can determine what to access and where to store the data. There are twotables in the logging database are updated with the logging parameters of the system so that thenumber of measurements to be logged, the logging frequency, and the retention period. Controlder to obtain the logging system parameters. The required table sizes are calculated using theging group according to the chosen parameters. The TCR reference database is accessed in orOne module of this component then builds or alters the logging tables required for a logthus permitting the data to be automatically restored should this be required. OCR Outputthe data. The name of the compressed tile contains the logging group code and the archive date,control tables. Archiving consists of exporting the table data to the Hle system and compressingdetermines the number of logging systems running and their data retention periods by reading theregularly to the tile system. This is done for each logging group by the archive program, whichSince data is kept online for rapid access for typically one to two months, it is archived3.4 ArchivingFIGURE 3; Data access and storage moduleSupcmsorsystemavailability flagloggingerror set database _ wm: to mesend mail todatabasewrite t0erroravailability flagtest database108 file measarementerror I write to error V¤·l¤€ f¤\’set emucommandissue readwait setabsentbulfcr filepI'¢S€I\l I pyoggggbuffer filetest presence offor read commandbuild data structuresoksystemfailureic errcr exit with¢¤’0f I riaigzghdetailsmeasurementread DB forbeen improved, better treatment of data access errors is overdue. Moreover, with the advent of OCR Outputadaptation of the data access modules. Though diagnostics on the logging processes has steadilyquence is constantly evolving, for example, new requests for logging different data sources meanThe product has been of significant use to many different services at CERN and as a conseit is envisaged to create two independent set—ups.that the use of one single facility for SL and TCR does not permit optimization for both parties;Original design weaknesses are gradually being corrected. Our experience leads us to concludethe logging programs and to an optimization of the tiles used for error reporting and archiving.ber of measurements to be logged led to changes in the conliguration of the machine runninging correctly. The expansion of the application to cover more than the originally planned numfor each logging group; these can then be analysed to determine whether equipment is functionmay not always be possible. Errors in obtaining data are now logged themselves in a separate Hlecess to the measurements, which are distributed over a wide area across a number of networks,These can sometimes be overlooked and cause problems that are not immediately detected. Aclead to incompatibilities or may imply a modification of some part of the logging application.standard tools, either provided commercially or made in-house. Each new release of a tool maydatabase, or the database server itself, must be correctly handled. The product uses a number ofAccessing a remote database requires that the unavailability of the machine running theenced during the evolution of the product over the past two years.The logging programs are generally reliable, though certain problems have been experi4 PERFORMANCE, PROBLEMS, PERSPECTIVESX-Window emulator if used on PCs and Macintoshes.This program uses the X-Window protocol for data display and thus must be run on anprocessed accordingly.ferring to the data requested. If the file is found it is restored to the database and the request isShould the data required for display not be available online, the archive is searched for a tile reX-Windows programming. The graph displayed can be updated with new data if so requested.built on top of the Xplore package, allowing the use of XRT Motif widgets without the need forwith the appropriate display parameters. The display program uses in-house graph templatesOnce the required measurements have been selected, the graphical display program is calledinformation on which the menus are built is obtained once again from the logging control tables.ing names with which he is familiar rather than the table and column names themselves. Themenu-driven user-interface which guides the user by presenting the available measurements ussurements, the other for handling the graphical display. The data selection part consists of aThe data display module is divided into two parts, one for managing the selection of meamodule was developed to satisfy these goals.lecting the measurements for display, and also lack functionality such as zooming, a speciticHowever, since such tools do not present a sufticiently well-tailored interface to the user for seinterfaces with the database, e. g. EXCEL can be used to retrieve data and display it graphically.Once the data is stored on the ORACLE tables, it is publicly accessible by any tool that3.5 Data DisplayIn addition, the archive program also updates summary tables for groups that require them.process of being determined.water which it discards into the local rivers. For other data, the archive retention policy is in theCERN has a legal obligation to keep a 10 year record of the pH and temperature of theinfrastructure at CERN, to appear in Proc. 1CALEPCS’95.[3] P. Ninin etal., The Technical Data Sewer for the control of 100 000 points of the technicalpp. 170-172.LEP accelerators in Proc. ICALEPCS’93, Nucl. Instrum. Methods Phys. Res. A352 (1994)[2] P Lienard, Evolution of the SPS and LEP communication control network for the SPS andMethods Phys. Res. A352 (1994) pp. 296-299.lll R. Billen et al., LEP Accelerator logging system using on—line database, Nucl. Instrum.Referenceslogging will be made and this will of course have a signiticant impact on the product.new control software [3] in the technical services domain, a move towards more event-driven

Data logging for technical services at CERN

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