The final LHC dipole series test set-up will consist of 12 benches, organised in 6 clusters of two benches sharing the largest and most expensive devices. This sharing is made possible by a deliberate de-phasing of the tests among magnets, ensuring an optimum use of resources, such as cryogenics and power equipment, without limiting the total throughput. To orchestrate the measurements a Test Master is needed to organise the tests per cluster and a Resource Manager to centralise the booking of the resources

Coutinho-Ferreira, P M

Gorskaya, E A

Raimondo, A

Reymond, H

Rijllart, A

CERN Document Server

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCHEuropean Laboratory for Particle PhysicsORCHESTRATING THE MEASUREMENTSON TWELVE MAGNET TEST BENCHESA. Rijllart1, P. Coutinho-Ferreira1, E. Gorskaia2, A. Raimondo1 and H. Reymond1The final LHC dipole series test set-up will consist of 12 benches, organised in 6 clusters of two benchessharing the largest and most expensive devices. This sharing is made possible by a deliberate de-phasing ofthe tests among magnets, ensuring an optimum use of resources, such as cryogenics and powerequipment, without limiting the total throughput.To orchestrate the measurements a Test Master is needed to organise the tests per cluster and a ResourceManager to centralise the booking of the resources.1  CERN, Geneva, Switzerland2  JINR, Dubna, RussiaPresented at the Eighth European Particle Accelerator Conference (EPAC)3-7 June 2002 - La Villette, Paris, FranceGeneva, Large Hadron Collider ProjectAdministrative SecretariatLHC DivisionCERNCH - 1211 Geneva 23SwitzerlandLHC Project Report 575Abstract2 July 2002ORCHESTRATING THE MEASUREMENTSON TWELVE MAGNET TEST BENCHESA. Rijllart, P. Coutinho-Ferreira, A. Raimondo, H. Reymond, CERN, Geneva, SwitzerlandE. Gorskaia, JINR, Dubna, RussiaAbstractThe final LHC dipole series test set-up will consist of12 benches, organised in 6 clusters of two benchessharing the largest and most expensive devices. Thissharing is made possible by a deliberate de-phasing of thetests among magnets, ensuring an optimum use ofresources, such as cryogenics and power equipment,without limiting the total throughput.To orchestrate the measurements a Test Master isneeded to organise the tests per cluster and a ResourceManager to centralise the booking of the resources.1 INTRODUCTIONThe next large accelerator project at CERN is the LargeHadron Collider [1] (LHC), which is foreseen to beinstalled in the existing LEP tunnel, and scheduled to becommissioned in 2007. For this project 1200, 15 metrelong dipole magnets need to be tested at CERN in warmand cold conditions on dedicated test benches that areunder development.An important part of the test is the magnetic fieldmapping. Dedicated software has been developed toperform this measurement in the LHC magnets by meansof the rotating coil method [2].Rotating coils, mounted on a shaft driven by a motor,deliver signals proportional to the magnetic field and therotation speed. The coil signals are integrated by digitalintegrators, which are triggered by an angular encoder.The integrators, on a VME bus, are configured and read-out by a computer through a VME interface. Figure 1show a sketch of the measurement system.From the raw data the software computes the mainfield, the main field direction, the higher order harmonicsand the magnetic axis coordinates. To perform thesemeasurements the computer controls motors, powersupplies and measurement devices, and reads-out theacquired data. Finally, it analyses online the raw data andstores it for later offline treatment.The ratio of measurement time versus preparation timeallows a de-phasing of the tests without limiting the totalthroughput where the largest and most expensiveresources, such as cryogenics and power supplies, can beshared into clusters of two benches for a total of 6clusters.To orchestrate the measurements a Test Master (TM) isneeded to organise the tests per cluster and a ResourceManager (RM) to centralise the booking of the resources.Each TM drives two VME based measurement systemsthat interface to the magnet test electronics. The first is aturnkey industrial DAQ system for magnet power testsand the second is an in-house developed magneticmeasurement system based on industrially producedcomponents. The TM’s user interface has been designedto allow non-specialist operators to execute pre-definedtests.The control architecture is organised in two levels,where the TMs are at the bottom level, driving themeasurement for the clusters, and requesting the bookingof required equipment to the RM at the top level.2 THE CONTROL ARCHITECTUREWe propose a control architecture with two levels [3]:• the TM which drives the test for a cluster;• the RM that allocates common devices and centralresources.In next sections we describe our implementation of thisarchitecture in the LabVIEW“ environment.2.1 The Test MasterThe TM will be used to perform in an automatic way apredefined measurements cycle and should be a commoninterface for all the applications to be used in a clustersuch as power supply control, magnetic measurementsand energy loss measurements.The aim is to simplify the way to perform themeasurement allowing users with minimum experience toperform tests, and to minimise time and errors, during testdefinition.To do this, the TM displays a synoptic panel thatdescribes the cluster that is being controlled. In thisdiagram, the lines represent the communication betweenTM and the low-level programs that are located indifferent computers. The colour of these lines describesthe communication status. The boxes that can be seenFigure 1: The magnetic field mapping system.represent the programs status and indicate in whichcomputer they are installed.TM has several operating modes to configure theexecution of measurements in a cluster.The first mode (install mode) is used to select thecomputers of the cluster that we want to control. In thismode, TM gets also the names of the configuration filespresent in the remote computers, which will be used tocreate the test files in the next mode (define test mode).These tests are in fact a list of commands written in a textfile replacing the same operations that the user would doin the low-level programs, which operate the hardwareand make the data acquisition.In one test, the TM sends several command files, usingFTP, to the program that performs the measurement andto the programs that make the low frequency and highfrequency data acquisitions. These two types of programsare located in different computers.To define a new test or to modify existing tests, the TMoffers a specific editor that proposes a list of predefinedcommands. After creating the necessary tests, the user canbuild a sequence with these tests in the build sequencemode. Finally, in the run sequence mode the user canlaunch a sequence of tests. Figure 2 shows the runsequence mode cluster synoptic.During a sequence execution the status of eachmeasurement is shown and a log is being kept. For eachtest in the sequence, the TM configures and runs severalapplications in parallel (magnetic field mapping,temperature data acquisition, etc.) and communicates withthe RM for status information and resource allocation.The information coming from the remote programslaunched by TM is obtained through a UDP socket. Thistype of communication doesn’t need to have TM workingnor a network, because it doesn’t verify if the are beingreceived.2.2 The Resource ManagerThe RM monitors the activity of TMs and the totalpower consumption. It shows the status of each test benchand handles the resource allocation on request of theTMs. It can refuse the use of a power supply if the totalpower consumption exceeds the limit.The aim of the RM is to give an overview of allongoing tests to the operators to help making decisionsabout the program in case it has to be changed dependingon individual magnet test results. Normally a magnet willfollow a standard program, but depending on resultsobtained during the test it may be necessary to shorten orextend the program. Such a change can influence theprogram on other clusters because of the common limitedresources of cryogenics and electrical power.2.3 Systems InteractionsWhen a measurement requires a particular powersupply, the TM needs to reserve it and keeps control of itfor the full time of the measurement. It is the RM thattakes care of power supply reservation. The TM asks theRM if the needed device is available through a query on aUDP socket. The TM continues to send queries to the RMuntil an answer has been received.Through another UDP socket the RM sends the answerallowing or not the measurement. With the reservationeach TM gives an estimate of the total booking time thatis updated during the measurement.The measurement can start once the power supply isavailable. At the end, the TM sends to the RM theinformation to deallocate the device through a system asbefore. If the power supply cannot be used the RM givesan estimate of how much is the waiting time. Then theTM allows the user to take a decision to wait or to changethe test sequence. Figure 3 shows the control architecture.The RM acquires the information through Ethernet byuse of a UDP socket mechanism.The use of UDP sockets is preferred over TCP becauseit does not need a permanent connection between theprocesses: this way, the TM can also run if the RM is notFigure 3: The control architecture.Figure 2: The run sequence mode synopticrunning or if there is no network communication with theRM. Only when needed, the communication takes placewith a sort of simulation of TCP connection given that forevery command sent the receipt is expected. During themeasurement each bench sends status and usageinformation to the RM, which shows to a supervisor userthe full installation.3 CONCLUSIONSFor the LHC project 1200, 15 metre long dipolemagnets need to be tested at CERN in warm and coldconditions on 12 dedicated test benches. The resourcesare shared in cluster of two benches, because of adeliberate de-phasing of the tests between magnets. Thismakes an optimum use of the resources, such ascryogenics and power equipment, without limiting the testthroughput.All measurement operations within a cluster can becontrolled by measurement scheduler software called TestMaster. The necessity of overall supervision software toshare the total available electrical power is provided bythe realisation of a Resource Manager.4 REFERENCES[1] The LHC Study Group, The LHC Conceptual DesignReport, CERN/AC/95-05(LHC)[2] L. Walckiers et al., "The Harmonic Coil Method",proc. of CAS, CERN 92-05, 1992[3] A. Raimondo et al., "The Test Master", Note CERNIAS-LS-00-003

Orchestrating the measurements on twelve magnet test benches

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