SCADA Architecture With Mobile Remote Components

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WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon KimSCADA Architecture with Mobile Remote ComponentsTai-hoon KimMultimedia Engineering Department,Hannam University133 Ojeong-dong, Daeduk-gu, Daejeon,Koreataihoonn@hnu.krAbstract: - With the advent of new technologies, the demand of connecting IT systems to the Internet is increasing. Thisis also the case for Control systems specifically SCADA (Supervisory Control and Data Acquisition) systems.Traditional SCADA systems are connected only in a limited private network. Because SCADA is considered a criticalinfrastructure, some operators hold back on connecting it to the Internet. Connection SCADA systems to the internet canalso provide a lot of advantages in terms of control, data viewing and generation. Along with these advantages, aresecurity issues regarding web SCADA, operators are pushed to connect SCADA systems through the Internet. Becauseof this, many issues regarding security surfaced. Mobility is also in demand in many IT systems. In this paper, thearchitecture of SCADA in the web with remote sensors is discussed. We believe that having mobile components canimprove the performance and it can provide larger operational coverage for SCADA systems.Key-Words: - SCADA, Mobility, Remote Components, Control Systems1 IntroductionThe motivation of this paper is the mobilityproblems is current SCADA systems. With the aid ofthe mobile IP Technology, we propose thisarchitecture for SCADA systems. On the next partsof this paper, we discuss the related technologies, theSCADA system, its parts and functionality, the webSCADA architecture, and the proposed architectureand its functions.SCADA is a system that collects data from varioussensors at a factory, plant or in other remotelocations and then sends this data to a centralcomputer which then manages and controls the data.SCADA and other Control Systems have been soimportant since it control most of our commodities.Conventional SCADA communications has beenPoint-to-Multipoint serial communications overlease line or private radio systems. With the adventof Internet Protocol (IP), IP Technology has seenincreasing use in SCADA communications. Theconnectivity of can give SCADA more scale whichenables it to provide access to real-time data display,alarming, trending, and reporting from remoteequipment.ISSN: 1991-87632 Related TechnologiesIn this section, the related technologies are discussed.Related Technologies for this study includes theLocation Based Service (LBS), Mobile Ad HocNetwork (MANET), Mobile IP and 4G MobileSystem.611Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon Kimas noted in ISO/IEC 19762-5 [10] and ISO/IEC24730-1 [11].2.1 Location Based Service (LBS)In today’s age of significant telecommunicationscompetition, a mobile network operatorcontinuously seeks new and innovative ways tocreate differentiation and increase profits. One of thebest ways to do accomplish this is through thedelivery of highly personalized services. One of themost powerful ways to personalize mobile servicesis based on location. We will discuss Location BasedServices (LBS), but we will first discuss the basis ofLBS - location technology. The components ofLocation Based Service can be found in the nextfigure.A location-based service is able to providetargeted spatial information to mobile workers andconsumers. These include utility locationinformation, personal or asset tracking, conciergeand route-guidance information, to name just a fewof the possible LBS. The technologies andapplications of LBS will play an ever increasinglyimportant role in the modern, mobile,always-connected society.2.2 Mobile Ad Hoc Network (MANET)An LBS (location-based service) is anentertainment and information service, accessiblewith mobile devices through the mobile network andutilizing the ability to make use of the geographicalposition of the mobile device [6] [7] [8]. LocationBased services can be used in a variety of contexts,such as work, health, personal life, etc. [9].MANETs are a kind of wireless ad hoc networksthat usually has a routable networking environmenton top of a link layer ad hoc network. They are also atype of mesh network, but many mesh networks arenot mobile or not wireless. Many academic papersevaluate protocols and abilities assuming varyingdegrees of mobility within a bounded space, usuallywith all nodes within a few hops of each other andusually with nodes sending data at a constant rate.Location Based services include services toidentify a location of a person or object, such asdiscovering the nearest banking cash machine or thewhereabouts of a friend or employee. LBS servicesinclude parcel tracking and vehicle trackingservices.Different protocols are then evaluated based onthe packet drop rate, the overhead introduced by therouting protocol, and other measures. A mobile adhoc network (MANET), sometimes called a mobilemesh network, is a self-configuring network ofmobile devices connected by wireless links. [12]Figure 2 shows that when devices are in Ad Hocmode, it creates a wireless mesh network. Eachdevice in a MANET is free to move independently inany direction, and will therefore change its links toother devices frequently. Each must forward trafficunrelated to its own use, and therefore be a router.The primary challenge in building a MANET isequipping each device to continuously maintain theinformation required to properly route traffic. Suchnetworks may operate by themselves or may beconnected to the larger Internet.Figure 1. Components of LBSThis concept of location based systems is notcompliant with the standardized concept of real timelocating systems and related local services (RTLS),ISSN: 1991-8763A MANET is a collection of wireless mobile612Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon Kimnodes that are dynamically and arbitrarily located insuch a manner that the interconnections betweennodes are capable of changing on a continual basis.[16]challenging. The following attributes are importantissues related to mobile ad hoc networks, especiallyfor those security-sensitive applications: [16]The connections between network devices arewireless, and the communication medium isbroadcast. The wireless connection provides thenodes with freedom to move, so the mobile nodesmay come together as needed and form a network,not necessarily with any assistance from the cableconnections.- Availability ensures the survivability of networkservices despite denial of service attack.- Confidentiality ensures that certain information isnever disclosed to unauthorized entities.- Integrity guarantees that a message beingtransferred is never corrupted.MANETs do not have any fixed infrastructure. Itis only a collection of self-organized mobile nodes,which are connected through high-variable qualitylinks. Thus, the network topology is alwayschanging. Third, the membership is always changing.The mobile nodes are free to move anywhere, leaveat any time and new nodes can enter unexpected.There is no mechanism to administrate or managethe membership.Fourth, the execution environmentis insecure and unfriendly. Due to the lack of fixedinfrastructure and administration, there are increasedchances malicious nodes can mount attacks. Also,nodes may behave selfishly and result a degradationof the performance or even disable the functionality.[16]- Authentication enables a node to ensure theidentity of the peer node it is communicating with.- Non-repudiation ensures that the origin of amessage cannot deny having sent themessage.Because of the nature of ad hoc, it isextremely difficult to achieve the above securitygoals in mobile ad hoc networks. Threats thatmobile ad hoc networks have to face can beclassified into two levels: attacks on the basicmechanism and attacks on the securitymechanism. The vulnerability of the basicmechanism includes:- Nodes risk being captured and compromised.- Algorithms are assumed to be cooperative, butsome nodes may not respect the rules.- Routing mechanisms are more vulnerable.Vulnerability of the security mechanism includes:- The trusted server can fall under the control of amalicious party.- Public key can be maliciously replaced.- Some keys can be compromised.Figure 2. Mobile Ad Hoc Network. Laptops in AdHoc mode creates a wireless mesh network.MANETs may encounter security threats. MANETsare networks with no fixed infrastructure andnetwork functions are carried out by all availablenodes, which are highly mobile and have constrainedpower resources . Consequently, mobile ad hocnetwork has increased sensitivity to nodeIn MANET, all networking functions like routingand packet forwarding, are performed by the nodesthemselves in a self-organizing manner. For thisreason, such networks have increased vulnerabilityand securing a mobile ad hoc network is veryISSN: 1991-8763613Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon Kimmisbehavior. There are two sources of attacks relatedto node misbehavior in mobile ad hoc networks. Thefirst is external attacker, in which unauthenticatedattackers can replay old routing information or injectfalse routing information to partition the network orincrease the network load. The second is internalattack, which comes from the compromised nodesinside the network.[16]address every time it changed itslocation. However, this would lead to breaking alltransport and higher layer connections.The Mobile IP protocol allows the mobile node(MN) to move among various subnets withoutchanging its home address (HoA). This protocolmakes this movement absolutely transparent tohigher layers and packets destined to this node canrouted through the network regardless its currentlocation. The Mobile IP protocol is suitable forproviding mobility among subnets of the same kindof access media as well as across various accessmedia kinds.2.3 Mobile IP (IP mobility)The mobile IP protocol allows location-independentrouting of IP datagrams on . Each mobile node isidentified by its home address disregarding itscurrent location in . While away from its homenetwork, a mobile node is associated with a care-ofaddress which identifies its current location and itshome address is associated with the local endpoint ofa tunnel to its home agent.Mobile IP specifies how a mobile node registers withits home agent and how the home agent routesdatagrams to the mobile node through the tunnel[13].Mobile IPv6 is a version of Mobile IP - a networklayer IP standard used by electronic devices toexchange data across a packet switchedinternetwork. Mobile IPv6 allows an IPv6 node to bemobile—to arbitrarily change its location on an IPv6network—and still maintain existing connections[14].Figure 3. Mobile IPv6 ScenarioThere are 3 entities defined in MIPv6 – MobileNode (MN), Correspondent Node (CN) and HomeAgent (HA). There are also access routers (AR) –Previous Access Router (PAR) and Next AccessRouter (NAR). MN is a mobile workstation roamingamong different subnets. CN is a node thatcommunicates with the MN. HA is usually a routerin the home network of MN. When the MN leavesboarders of its home subnet, it notifies its HA. TheHA creates a mobile binding, which is an associationbetween the home IP address and current Care ofAddress (CoA) – a temporary IP addresstopologically correct in the visited subnet. After thatthere are two ways of delivering the data betweenMN and CN – bidirectional tunneling or route2.3.1 Mobile IPv6The MIPv6 (Mobile IPv6 protocol) is a layer 3protocol that allows mobile services users (mobilenodes) to stay reachable independently on the mobilenode’s movement in the IP environment. Without themobility support in IPv6 protocol, the trafficdestined to the mobile node could not be delivered asfar as the mobile node was situated out of its homenetwork. For keeping its connectivity in such casethe mobile node would need to acquire a new IPISSN: 1991-8763614Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon KimWeb, is started from 4G technologies. The followingevolution will based on 4G and completed its idea toform a real wireless world. Thus, 5G should make animportant difference and add more services andbenefit to the world over 4G. 5G should be moreintelligent technology that interconnects the entireworld without limits. [17]optimization.2.4 4G Mobile System4G mobile system is an all IP-based networksystem. Its features can be summarized with oneword—integration. The 4G systems are aboutseamlessly integrating different technologies andnetworks to satisfy increasing user demands.4G technologies shall combine different currentexisting and future wireless network technologieslike IPv6, OFDM, MC-CDMA, LAS-CDMA andNetwork-LMDS to ensure freedom of movementand seamless roam from one technology to another.These will provide multimedia applications to amobile user by different technologies through acontinuous and always best connection possible.[17]3. Supervisory ControlAcquisition SystemsThe 4G networks are integrated with one corenetwork and several radio access networks. A coreinterface is used for communication with the corenetwork and radio access networks, and a collectionof radio interfaces is used for communication withthe radio access networks and mobile users. Thiskind of integration combines multiple radio accessinterfaces into a single network to provide seamlessroaming/handoff and the best connected services.Supervisory Control and Data Acquisitionsystem is compose of collecting of the information,transferring it to the central site, carrying out anynecessary analysis and control and then displayingthat information on the operator screens. Therequired control actions are then passed back to theprocess. [1]. Typically SCADA systems include thefollowing components: [2]The difference between 3G and 4G is the datarates. 4G can support at least 100Mbps peak rates infull-mobility wide area coverage and 1Gbps inlow-mobility local area coverage. The speeds of 3Gcan be up to 2Mbps, which is much lower than thespeeds of 4G. But 4G standard will base onbroadband IP-based entirely applying packetswitching method of transmission with seamlesslyaccess convergence.1.Operating equipment such as pumps, valves,conveyors and substation breakers that can nts in the field or in a facility thatsense conditions such as pH, temperature,pressure, power level and flow rate.DataTelemetry is automatic transmission andmeasurement of data from remote sources by wire orradio or other means. It is also used to sendcommands, programs and receives monitoringinformation from these terminal locations. SCADAis the combination of telemetry and data acquisition.2. Local processors that communicate with the site’sinstruments and operating equipment. Thisincludes the Programmable Logic Controller(PLC), Remote Terminal Unit (RTU), IntelligentElectronic Device (IED) and Process AutomationController (PAC). A single local processor maybe responsible for dozens of inputs frominstruments and outputs to operating equipment.4G integrated all access technologies, servicesand applications can unlimitedly be run throughwireless backbone over wire-line backbone using IPaddress. But 5G will bring us perfect real worldwireless or called “WWWW: World Wide WirelessWeb”. The idea of WWWW, World Wide WirelessISSN: 1991-8763And3. Short range communications between the local615Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon Kimprocessors and the instruments and operatingequipment. These relatively short cables orwireless connections carry analog and discretesignals using electrical characteristics such asvoltage and current, or using other establishedindustrial communications protocols.equipment. Programmable logic controllers or PLC'sare still the most widely used control systems inindustry. As need to monitor and control moredevices in the plant grew, the PLCs were distributedand the systems became more intelligent and smallerin size. PLCs(Programmable logic controllers) andDCS (distributed control systems) are used as shownin Figure 4.4. Host computers that act as the central point ofmonitoring and control. The host computer iswhere a human operator can supervise theprocess; receive alarms, review data and exercisecontrol.3.2 The Human Machine InterfaceSupervisory Control and Data Acquisition Systemsusually have Distributed Control Systemcomponents. PLCs or RTUs are also commonlyused; they are capable of autonomously executingsimple logic processes without a master computercontrolling it. A functional block programminglanguage,5. Long range communications between the localprocessorsandhostcomputers.Thiscommunication typically covers miles usingmethods such as leased phone lines, satellite,microwave, frame relay and cellular packet data.IEC 61131-3, is frequently used to createprograms which run on these PLCs and RTUs. Thisallows SCADA system engineers to perform boththe design and implementation of a program to beexecuted on an RTU or PLC. From 1998, major PLCmanufacturers have offered integrated HMI/SCADAsystems, many use open and non-proprietarycommunications protocols.3.1 SCADA Traditional SetupThe function of SCADA is collecting of theinformation, transferring it back to the central site,carrying out any necessary analysis and control andthen displaying that information on a number ofoperator screens. Systems automatically control theactions and control the process of automation.Many third-party HMI/SCADA packages,offering built-in compatibility with most majorPLCs, have also entered the market, allowingmechanical engineers, electrical engineers andtechnicians to configure HMIs themselves.The goal of human-machine interactionengineering is to produce a user interface whichmakes it easy, efficient, and enjoyable to operate amachine in the way which produces the desiredresult. This generally means that the operator needsto provide minimal input to achieve the desiredoutput, and also that the machine minimizesundesired outputs to the human.Figure 4. Common SCADA Installation utilizingPLC, Sensors and master station connected using afieldbus.Conventionally, relay logic was used to controlproduction and plant systems. With the discovery ofthe CPU and other electronic devices, manufacturersincorporated digital electronics into relay logicISSN: 1991-8763Ever since the increased use of personalcomputers and the relative decline in societal616Issue 8, Volume 5, August 2010

WSEAS TRANSACTIONS on SYSTEMS and CONTROLTai-Hoon Kimcontrols where the individual can interface with theSCADA system. HMI's are an easy way tostandardize the facilitation of monitoring multipleRTU's or PLC's (programmable logic controllers).Usually RTU's or PLC's will run a pre programmedprocess, but monitoring each of them individuallycan be difficult, usually because they are spread outover the system. Because RTU's and PLC'shistorically had no standardized method to displayor present data to an operator, the SCADA systemcommunicates with PLC's throughout the systemnetwork and processes information that is easilydisseminated by the HMI. HMI's can also be linkedto a database, which can use data gathered fromPLC's or RTU's to provide graphs on trends, logisticinfo, schematics for a specific sensor or machine oreven make troubleshooting guides accessible. In thelast decade, practically all SCADA systems includean integrated HMI and PLC device making itextremely easy to run and monitor a SCADAsystem.awareness of heavy machinery, the term userinterface has taken on overtones of the (graphical)user interface, while industrial control panel andmachinery control design discussions morecommonly refer to human-machine interfaces.Figure 5. An Example of a SCADA HumanMachine InterfaceThe design of a user interface affects the amountof effort the user must expend to provide input forthe system and to i

Key-Words: - SCADA, Mobility, Remote Components, Control Systems 1 Introduction SCADA is a system that collects data from various sensors at a factory, plant or in other remote locations and then sends this data to a central computer which then manages and controls the data. SCADA and other Control Systems have been so important since it .

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