资源描述：
《毕业设计（论文）：【毕业设计英文翻译】可编程控制器的数据库系统》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、DatabaseSystemsforProgrammableLogicControllersABSTRACTInthispaper,weidentifythedatabaseissuesassociatedwithprogrammablelogiccontrollers(PLC),special-purposecomputersusedinscientificandindustrialapplications,e.g.infactoriesinmanufacturingenvironments.Wepr
2、oposeasaPLCdatabasesystemasingle-user,real-time,scalablemain-memory-onlyrelationaldatabasesystemwithatwo-levelarchitecturehavinghistoricaldatamodelingandmanipulationcapabilities,andqueryprocessingtechniquesincorporatingtime-and/orerror-constrainedqueryev
3、aluation.Werevisetheladderlogiclanguage,themostcommonPLClanguage,toincorporatedatamanipulationlanguageinstructions.WeaddaseparatetimecomponentintothePLCprocessorscantimetohandledatabaseupdates,backup,integrityenforcementanddataarchivalissues.1.Introducti
4、onAprogrammablelogiccontroller(PLC)isaspecial-purposecomputerusedwithinreal-timescientificcomputingsystems,andindustrialcontrolsystems,say,theautomatedcontrolofafactory'smachinery-therunningexampleusedinthispaper.ThispaperisapositionpaperthatproposesaPLC
5、databasesystemanddiscussesitsfeatures.Indoingso,wetouchbaseswithanumberofbasicdatabasetopics,and,thus,frequentlyrefertootherworkfordetails.PLCsaremostlyusedinmanufacturingenvironments-hence,thechoiceofourrunningexample.However,PLCsarealsousedinscientific
6、applicationsforsignaldatagatheringandpreliminarydataprocessing.Thus,wethinkthatforsomescientificapplications,aPLCdatabasemayalsoserveasalocal/transientpartofalargerscientificdatabase.Withtherapidadvancesincomputerhardwareandfallingmemoryprices,inrecentye
7、ars,thecapabilitiesofthenewPLCsinthemarketplacehavebeenincreasingdramatically.ThispaperisapositionpaperthatarguesthataPLCsoftwarecannowcontainadatabasesystemtogreatlyincreaseitsfunctionality.WeproposethearchitectureinFigure1asthearchitectureofanenvironme
8、ntwherereal-timedatagathering(frommultiplesensors)andreal-timedatamanipulationtakesplace.WenowlisttheadvantagesofhavingadatabasesystemdirectlyinsideaPLC.(1)DataModelingTechniques:Theinputandoutputbuffersrepresentaratheruno
