Khomenko, B A

Manno, I

Michel, E

Raimondo, A

Reymond, H

Rijllart, A

Sheehan, M

Vacchetti, L

CERN Document Server

INTEGRATION OF CUSTOM SYSTEMS INTO INDUSTRIAL SYSTEMSFOR LHC COMPONENT TEST BENCHESA. Rijllart, B. Khomenko, I. Manno, E. Michel, A. Raimondo, H. Reymond, M. Sheehan, L.Vacchetti, CERN, Geneva, SwitzerlandAbstractThe LHC component acceptance test benches requireintegrated controls, data acquisition and measurementsystems. For this purpose CERN-built custom systemshave been integrated into industrial systems. Theapproach that we have used for the integration is based onthe usual tree structure, extended with a new feature toallow device sharing: the "tower" structure. Examples ofintegrated systems are given, one on a magneticmeasurement bench, the other on a superconductingstrands test bench. Related aspects of remote monitoringand control are covered.1 INTRODUCTIONA typical acceptance test bench of LHC componentsconsists of industrial systems as well as custom systems,which need to be integrated into the former. Industrialsystems have been used as much as possible [1,2], but forapplications where these were not available, customsystems have been developed. For example the LHCdipole magnets test bench is composed of two industrialsystems, one for Cryogenic Control, the other for QuenchRecording, and a custom built Magnetic MeasurementSystem (MMS) [3].An important characteristic of such a system is thatfrequent changes are necessary and new equipment has tobe integrated. For example the integration of a new typeof measurement is done by adding new specificequipment, but the new control software needs also toaccess an existing device already used by anotherapplication.A tree-structured architecture does not allow access onthe same control level. Existing solutions such as using alower level (hardware switches) or communicationthrough a higher level are not satisfactory because they areeither not flexible or have poor performance in timeresponse and reliability.  To meet our requirements of flexibility and goodtime response we have developed a new architecture,called "tower" in contrast to "tree", that allowscommunication at the same control level.In the following sections the general architecture isdescribed and some examples of integration with othersystems are given.2 GENERAL ARCHITECTURE2.1 Architecture OverviewIn a tower architecture (Fig. 1) we do not only havebranches but also cross links at the intermediate levelwhich reinforce the structure.Figure 1: The tower architecture.We define three levels:• The Front-End Level (FL), which is the low level,constituted by the peripheral devices like powersupplies, VME crates, motors etc, needs to becontrolled by a higher level. At this level, thedevices are not inter-communicants.• The Control Level (CL), which includes thecomputers and the software running on them, is theintermediate level. At this level, the system performsall kind of operations needed for the measurementsuch as controlling, reading out, storing andanalysing data coming from the FL. The computersare interconnected through Ethernet allowing the low-level equipment to be shared.• The Supervision Level (SL), connected throughEthernet to the CL, monitors processes and controlsthe status and the most important parameters of theCL. It logs all operations keeping track of the fulltest program.Using CL communication we can extend device controlto newly added applications keeping the advantage of thetree structured modularity. In this way industrial orcustom systems can not only be removed or substitutedInternational Conference on Accelerator and Large Experimental Physics Control Systems376International Conference  Accel rator and L rge Experim ntal Physics Control Systems, 1999, Trieste, Italywithout interfering with the other parts of the system, butcan also be added and given control over existing devices.To have a high modularity in hardware and in softwarewe have used industrial devices interconnected withstandard busses (VME, GPIB, RS232 and Ethernet) andwe have developed software written in LabVIEW¤.The final LHC magnets test setup will have amaximum of 12 benches with central supervision, whereeach set of two benches will share the most importantdevices. These devices are normally large and expensiveand, due to the nature of the test, they are not neededsimultaneously. An example of such a device is thepower supply used to feed the magnets.2.2 Power Supply SharingWe have implemented a multi-server system in which aset of clients has access to one particular server. Eachpower supply is physically connected to a server of theCL, but another computer (client) can use it.A computer of the CL which, for a particularmeasurement, requires a particular power supply, needs toreserve it and keeps control of it for the full time of themeasurement. To manage the power supply reservation,an access control system has been implemented. Once apower supply is reserved, it inhibits access from otherclients.The decision about access needs to be defined at theSL, where the overall system is monitored.2.3 The Monitor and the Access ControlThe Monitor is a process that runs at the SL. Itmonitors the different operations and access rights of thedifferent benches. This process acquires the informationthrough Ethernet by use of a UDP socket mechanism.UDP sockets do not need a permanent connectionbetween the processes: in this way, the CL can also run ifthe Monitor is not running or if there is no networkcommunication with the SL.The Access Control is also defined at the SL and theinformation of which client can control which device issent to each station of the CL through TCP sockets. Withthe use of this type of socket, we make sure that the CLcomputer is informed of the new settings.3 MOLE MAGNETIC MEASUREMENTSYSTEMAn example of integration is the Mole [4]. Its namewas chosen because of its small size and of its ability tomove a probe through a 15 metres LHC dipole magnet,for magnetic field quality measurement at roomtemperature.The Mole, a fully industrial turnkey system, includesan axial and rotating movement system driving ameasurement probe, a camera for the skew determination,and a local controller. This system has been integratedinto the CERN MMS using predefined specifications ofcommunication protocols and interfaces.The MMS consists of two parts: one is themeasurement electronics and the read-out system,including the display and analysis software; the other isthe axial and rotating movement system, including thesoftware control.Using the predefined communication protocol, theMMS has easily been integrated into the Mole, replacinga custom built part (Fig. 2). From the point of view ofsoftware, we have implemented a high level driver formoving the Mole, translating the generic commands tothose of the Mole, thus giving to the MMS full controlof the Mole.Figure 2: The Mole system.The Mole can be driven in remote mode by the MMSor by an application that emulates the local controller. Inthis way it is possible to remotely set the most importanthardware and software parameters.4 SUPERCONDUCTING STRAND TESTBENCHESAn example of a modular system is the measurementand control system of the Superconducting Strand testbenches (SStb). Seven small test benches connected toGPIB instruments and occupying in total 40 metres inlength needed to be controlled both from a central controlroom and locally.The large number of instruments, the important bustraffic they would generate and the large distance to becovered excluded the use of a single GPIB bus. On theother hand, to have one computer with a GPIB interfaceper test bench would have been a too costly solution.Therefore, we decided to use one GPIB/RS-232 converterper test bench. The seven serial lines, covering thedistance through current-loop transformers, connect eachset of instruments to a few central workstations in thecontrol room (Fig. 3). Local control is obtained with anX-terminal installed near a test bench and using one ofthe central workstations to access the instruments.377This system is flexible, because there is no directcorrelation between the number of workstations and thenumber of test stations. In addition, any screen can beassigned to the control of any test station, and everyscreen can display the summary information about thestate of the other stations.The connection of the GPIB/RS-232 converters toUnix workstations running LabVIEW¤ applicationsrequested the development of a driver. This was achievedin the form of a generic GPIB driver, implemented inLabVIEW¤ using RS-232 calls. Such a driver acceptsstandard GPIB commands and produces either GPIB callsor their equivalent in RS-232, depending on a softwareswitch. This makes the type of interface completelytransparent to the calling program. When using RS-232with a transmission rate of 38400 baud, the data transferspeed is only 15% slower than using the GPIB standard.Figure 3: The SStb connection.This driver is now being extended to include remotecalls over TCP/IP using the server system, which isdescribed in section 2.2. This will allow remotecomputers to access GPIB instruments that are physicallyconnected through GPIB or GPIB/RS-232 to the controlroom workstations.The access control principles and supervision describedin section 2.3 can be used for the SStb system withoutmodification.5 CONCLUSIONSIndustrial systems have the advantage of being readilyavailable and cost effective.Furthermore, the choice of widely used standardsprovides a simple integration of custom systems intoindustrial systems.However, changes in the measurement requirementsneed frequent extensions and adaptation. This can beachieved through the flexibility of the tower architecturewe have described that allows easy device sharing inaddition to the modularity of the tree structure.The Mole magnetic measurement system and theSuperconducting Strand test benches are examples ofusing this approach.REFERENCES[1] M. Rabany, Interfacing industrial process controlsystems to LEP/LHC , ICALEPCS 91, Japan,November 1991.[2] R.J. Lauckner, Integration of Industrial Equipmentand Distributed Control Systems into the ControlInfrastructure at CERN , ICALEPCS 97, China,November 1997.[3] J. Billan, 15 m long Twin Rotating Coils for coldmagnetic measurements of LHC dipoles , MT-16,U.S.A, October 1999.[4] L. Bottura, A Mole for warm magnetic and opticalmeasurements of LHC dipoles , MT-16, U.S.A,October 1999.378

Integration of Custom Systems into Industrial Systems for LHC Component Test Benches

Integration of Custom Systems into Industrial Systems for LHC Component Test Benches

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