Baldauf, R

Kleines, H

Kravtsov, P

Mikirtychiants, S M

Nekipelov, M

Rathmann, F

Sarkadi, J

Seyfarth, H

Vasilev, A

Zwoll, K

CERN Document Server

THE SLOW CONTROL SYSTEM OF THE ATOMIC BEAM SOURCE ATANKE/COSY –AN INDUSTRIAL APPROACH BASED ON WINCC AND S7 PLCSH. Kleines, J. Sarkadi, K. Zwoll, R. Baldauf, ZEL, FZJ, Jülich, GermanyF. Rathmann, H. Seyfarth, M. Mikirtytchiants, M. Nekipelov, IKP, FZJ, Jülich, GermanyA.Vassiliev, P. Kravtsov, PNPI, St. PetersburgAbstractFor the ANKE experiment at the medium-energy ringCOSY at Forschungszentrum Jülich, an Atomic BeamSource (ABS) is under development, which produces apolarized atomic beam (H or D atoms).  The necessaryfront-end equipment for the slow control system consistsof more than 100 components, including a variety ofvacuum pumps, vacuum gauges, RF generators, valves,leak detectors, temperature sensors, stepping motorcontrollers, PID controllers, flow controllers, etc. fromdifferent vendors. The slow control system should supportthe routine operation of the ABS as well as experimentaltests of the ABS itself.Safety reasons and economic considerations lead to thedecision to use mainly industrial equipment for the slowcontrol system. The Siemens product WinCC – runningon a PC under WinNT - has been selected as the core ofthe SCADA application. The interlock system has beenimplemented on the base of Siemens S7 PLCs.  In order tounify the interfacing to the control computer, all front-endequipment is connected via PROFIBUS DP. Proprietaryserial protocols are translated via dedicated gateways.1 INTRODUCTIONThe COSY Atomic Beam Source (ABS)[1] atForschungszentrum Juelich (FZJ) follows similaroperation principles as the existing HERMES ABS atDESY[2]. It has been finished to the extent necessary forfirst test measurements, e.g. the sextupole magnet systemis not yet installed. With regard to control, it is a mediumsized system with about 150 process signals and about 15serial interfaces to more complex devices, at the moment.Many aspects of its final layout are still open, but it isanticipated, that the system will have twice as muchcomponents, eventually.Control systems for accelerators or physics experimentsare dominated by “home-made” systems. But PLCs andother industrial equipment are increasingly being used.Especially at CERN there is a strong movement towardglobal industrial control solutions[3],[4].  Mainmotivations are:- low prices induced by mass market,- robustness- long term availability and support from manufacturer- powerful development toolsAlso at FZJ, the existing control technology is primarilybased on homemade systems, e.g. VME systems with aproprietary RT kernel are used in the front end, orSCADA (Supervisory Control and Data Acquisition)applications were developed from scratch as OSF/Motifbased programs[5]. Industrial automation technology isused only very reluctantly[6]. The above mentionedreasons require, that future large control systems shouldbe based on industrial automation equipment, mainly. Sothe medium sized ABS was selected to evaluate theconsequent use of industrial control technology.Figure 1: ABS schematic overview2 ABS OPERATIONThe COSY ABS produces a polarised atomic beam (Hor D atoms), which will interact with the protons of theaccelerator. A dissociator inside a vacuum vesselproduces a hydrogen plasma discharge, in which hydrogenmolecules are dissociating. Two RF transition units areused to polarise the atomic beam, which will feed astorage cell. Additional diagnostic systems for intensitymeasurements (intensity device), measurement of thedegree of dissociation (α-device) are temporarily includedin the ABS. Interaction of the ABS with COSY control,water cooling, leak detection and the complex movementof the storage cell are still not finalised. According to theschematic view in Fig. 1 the following major buildingblocks of the ABS are already implemented:Vacuum system: A differential pumping systemconsists of seven turbomolecular pumps, three diaphragmpumps and two cryo pumps. Valves can control severalDisssociatorCoolPakMagnetsRF unitsMagnetsRF unitsInternational Conference on Accelerator and Large Experimental Physics Control Systems359International Conference  Accel rator and L rge Experim ntal Physics Control Systems, 1999, Trieste, Italybypasses between the four stages of the vacuum vessel.Pressures are monitored by 8 vacuum gauges attached tothree MKS 146 C control units. Also temperatures aremonitored.Dissociator: The dissociator includes an industrial RFgenerator from Hüttinger for the plasma discharge as wellas flow controllers for the O2 and H2 gas supply. Thedissociator nozzle is cooled via a heat bridge to a coldhead (Leybold CoolPak). Two heaters, which arecontrolled by individual PID loops, are responsible for thetemperature stabilisation of cold head and nozzle.Intensity device: For absolute intensity measurementsa calibration system for a reference pressure wasimplemented that includes a vacuum pump, two flowcontrollers, ten valves and a manual operation panel. [7]α-device: This diagnostic instrument measures thedegree of dissociation. Equipment includes a chopper anda quadrupole mass spectrometer. [8]The control system had to be continuously modifiedduring the development process. The main building blocksof the future development phases will be:Hyperfine transition units: rf units being underdevelopment at the University of Erlangen have to beinstalled into the source. They will produce the desiredpolarisaton of hydrogen and deuterium atoms.Water cooling: Separate water cooling systems haveto be installed for the cryo pumps, turbo pumps, RFgenerator and the dissociator. This includes leak detectors,valves as well as sensors for pressure, temperature andflow.Storage cell: The storage cell temperature has to becontrolled. The storage cell should probably be retractablefrom the COSY beam orbit in order to facilitate tuning ofCOSY for other experiments. This may even requiremovement of ANKE detectors.Still many aspects of safety related interlocks andconnection to the COSY control system are open.3 MAJOR BUILDING BLOCKS OF THESLOW CONTROL SYSTEN3.1 Basic Design issuesThe ABS is an appropriate candidate for the consequentapplication of industrial control technology, because it hassafety relevant aspects requiring the application of robustindustrial PLC technology for the basic interlocks. Withregard to control it is a typical slow control system withmoderate timing and data throughput requirements. Sincethe expected number of process I/Os was in the order of afew hundreds, it seemed to be sufficient to base thecontrol system on a single PC, but this should beextendable. Additional boundary conditions were manpower restrictions, requiring powerful development tools.Since the specification for the ABS was still evolving andsubsystems should be tested individually, a high degree offlexibility was required from the development tools.Basic design decisions are related to front end PLC andI/O systems, the communication technology and thetoolkit for the SCADA system . These three basic buildingblocks determine flexibility, extendability and scalabilityof the system, as well as development productivity and theoverall economics. The following sections introduce andmotivate our selections.3.2 PROFIBUSPROFIBUS, being a national German (DIN 19245) andan European (EN 50170) standard, has become the mostwidely accepted modern fieldbus technology inEurope[9]. It is expected to take a similar role on theworld market, since the IEC standardisation efforts for acommon international fieldbus failed recently. A majorreason for its success is the technological and functionalscalability based on a common core.  Now, a wide rangeof PLCs as well as low cost process I/Os is available froma variety of manufacturers which enable easy interfacing.Most of the installed PROFIBUS equipment follows theprofile DP (decentral periphery), which has been designedfor the optimised connection of simple, low cost I/O in atime critical environment. Basically, a DP systemtransparently maps process I/Os to a dual ported RAM inthe host system. So PROFIBUS DP is now used by ZELas the common, integral path from controlling computersto industrial equipment in the front end[10]. ZEL tries touse commercial PROFIBUS equipment whereverpossible, but some existing gaps had to be filled by owndevelopments, e.g. PROFIBUS controller forCompactPCI, or PROFIBUS driver and configurationsoftware under Linux and LynxOS[11]. For the ABS onlycommercial components were used. The only exception isthe serial gateway introduced in subsection 3.5.3.3 S7 PLCs   S7 PLCs are the newest product line from Siemens.Siemens has been selected, because it is the dominatingmanufacturer of industrial automation equipment on theEuropean market. Additionally, the S7 series comes withpowerful development and diagnostic tools.  A big varietyof modules is available, also complex function modules(position controllers, PID controllers, etc.). PROFIBUS isthe well supported natural method of externalconnectivity.  PLC periphery can be transparentlyextended by ET200 type of distributed I/Os. The S7 seriesis scalable, but we are using only 315-2 CPUs.3.4 WinCCMain functions of the ABS SCADA software are• Monitoring (visualisation of the process state andhistory)360• Operator control (set parameters, switch on and offsubsystems or operations, acknowledge alarms)• Archiving of process variables and alarms• Communication with the process periphery andsupervisory computers (e.g. ANKE DAQ)Because of our man power restrictions, our mainrequirement was the availablity of powerful developmenttools for the SCADA software in order to increasedevelopment productivity. Additionally we required ahigh degree of flexibility, because we expected frequentchanges of the system during the development and testphase. A natural support for S7 PLCs and PROFIBUS DPwould be favourable.So it was clear that the classical development from thescratch (e.g. using Qt and pure C++) was no seriouschoice. Also “Lab automation” tools like LabView werenot considered, because they typically have no internaldatabase or predefined alarm system and have a quiteobscure graphical programming environment. EPICs wasfelt to be too big and the binding to VxWorks wasconsidered as a major disadvantage. Support forPROFIBUS DP was expected to be insufficient. As aconsequence we decided to acquire an industrial windowsbased package from the market, like e.g. Wonderware’sInTouch. The Siemens product WinCC was selectedbecause of support, long term availabilty and the naturalintegration of PROFIBUS DP and of several proprietrayprotocols for accessing Siemens PLCs. Main componentsof WinCC are• Graphical editor: Process pictures can be drawncomfortably and the attributes of graphical objectscan be connected to process variables transparently• Database: WinCC integrates SYBASE for the storageof process values and alarmes.• Alarm system• Variety of channel DLLs to support a lot of industrialnetworks and PLC typesWinCC is a PC based system that runs only underWindows NT/98 and offers most of the “open” interfaces(ODBC, OPC, DDE, OLE,...) found in a Microsoftenvironment. It can be structured as a client/server-system, but the server functionality can not be distributed.3.5 Serial GatewayAs a spin off from an industrial project, a DP slave wasdeveloped, that is equipped with 8 serial channels,supporting RS232 and RS485. As usual, the controllercore is implemented as an intelligent subsystem accordingto Fig. 2, with a central address/data/control busconnecting the CPU MC68340FE16, 512 KByteFlashEPROM, 256 KByte of static RAM and the protocolchip SPC4.An embedded application software on the MC68340implements those parts of the serial protocols for Pfeiffervacuum pumps and MKS 146C control devices forvacuum gauges, that are required by the ABS application.So the system serves as a gateway between these serialprotocols and PROFIBUS DP. Via this gateway, theprocess control computer can directly access pressures,status, set points or rotation speeds in the DP image, thusoffloading protocol handling and polling operations to thegateway.Figure 2: Block diagram of the serial gateway4 CONTROL SYSTEM ARCHITECTUREAccording to Fig. 3, there is one central controlcomputer, a PC running Windows NT with WinCC. Soprocess database and operator interface are on thismachine. All process I/O is connected via PROFIBUSDP. Temporarily, some “laboratory type equipment” isattached via GPIB. For the connection to ANKE DAQ, asimple protocol based on XDR and UDP has beenimplemented, that allows the transparent access to internalWinCC tags via Ethernet. Thus ANKE DAQ candownload setups to the ABS and continuously read backits status for inclusion in the data stream. The sameprotocol is used by a physics workstation for experimentaltests of the ABS itself.Process equipment includes three S7-300 PLCs, one forthe vacuum system, one for the intensity device and onefor chopper control, cold head temperature stabilisationand for the hyperfine transition units. A fourth PLC isunder preparation for leak detection and water cooling.A RF generator manufactured by Hüttinger as well astwo serial gateways are directly attached to PROFIBUSDP. Temperature stabilisation of the dissociator nozzle isdone in software by a WinCC script, at the moment. Thenecessary process I/O is done via ET200S distributed I/O.Also an ET200L system is directly attached toPROFIBUS DP, which controls a wire monitor for beamprofile analysis.Because the ABS is continuously changing during thedevelopment and many aspects of its final slow controlstructure are still open, the control software is stillevolving and can be considered as a prototype. Operatorinterface includes editing of most parameters, commandbuttons for vacuum and dissociator control as well astextual or graphical display of all relevant process values.----cut here by editor due to space restrictions!!!!Communication ControllerRAMPROFIBUSMAU68340 ProcessorFlashEPROM 8 *RS232 /RS485SPC4361

The Slow Control System of the Atomic Beam Source at ANKE/COSY: An Industrial Approach Based on WinCC and S7 PLCs

The Slow Control System of the Atomic Beam Source at ANKE/COSY: An Industrial Approach Based on WinCC and S7 PLCs

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