Industrial Control Using Wireless Networks - Report Example

Running Header: Industrial Control Using Wireless Networks Student’s Name: Instructor’s Name: Course Code & Name: Date of Submission: Industrial Control Using Wireless Network Table of Content Table of Content 2 Abstract 3 Introduction 4 PLCs, SCADA and DCS System 5 Bluetooth 7 Wireless LANS 7 Paging system 10 Limitations of Wireless Network 10 Conclusion 11 References 13 Abstract In the current technological world, the control networks have been advanced to such a level that they are able to merge with the corporate network in order to enable the control engineers to control and monitor systems from outside of the control system network. These kinds of network also speed up decision making process since they can also be designed to obtain data, access it and even process. In the current technology, there is continuous need to replace the cables and other wired networks. Instead there is need for deployment and utilization of wireless networks. However, the wireless network to be used should be able to meet the reliability needs of the current wired systems and be able to process and serve in real time. Applicability and convenience of the wireless networks for the purpose of the industrial control is what majorly matters for its applicability in real-time control. The main advantage of the wireless technology over the wired one is that it offers various numbers of possible services and applications which may lead to industrial fields. The IP base control for instance, can be used for control over the wireless networks and together with the internet would offer a very powerful remote control. Although wires may limit the main properties of applications, they still offer a better guarantee to the industrial control requirements in terms of reliable link and speed in real time communication. The design of the wireless system faces the challenges such as constrainable energy capacity, bandwidth limitation, processing power and memory limitations. Introduction The major purpose of the Wireless Network in industry is providing of the features that would be able to benefit local area network technologies like the Ethernet (Goldsmith 2005 pp 36). The wireless networks do not have the cabling limitations. Mediums like the infrared light and the radio frequencies are used instead. Currently, new technologies like Bluetooth and WLAN are available which uses about 2.4 gigahertz of the frequency transmission band. The transmission over the wireless medium would be based on two modifications based on spectrum method that are being standardized by the IEEE and also used in Bluetooth and WLAN. Two methods are used in this case. The first method is known as Fast Frequency Hopping Spectrum that does support the data rates of up to about 2 mega bytes per second. The method is also used with the devices that use Bluetooth. The other method used is the Direct Sequence Spread Spectrum which is able to support the data rates of up to 11 megabytes per second. Certainly, there are many advantages of replacing cables by wireless medium. Most significant of all is the reduction in the installation time, installation of areas that are difficult to wire, cost saving, flexibility and mobility. The major setback of the wireless network is they may be unreliable since these kinds of networks may be caused by reflection of the multipath effects and the crucial interference with other types of devices that may be using the same high frequency. Another major concern on these kinds of device is power. Normally, not everywhere will you find power supply to for the wireless network terminals. Back up powers like battery may not be attractive in the sense that the benefit of the wireless would be lost the moment replacement of the battery is necessary. The factory and the industrial environments do pose a major challenge for the wireless communication. The reliability in the industrial performance is only possible whenever the wireless protocols that are used by the devices do account for the operational obstacles that are associated with the hostile radio environments. A successful wireless network for the industrial control must meet the IEEE standard that have been defined under wireless Ethernet standard IEEE 801.11 and the more recently 802.11b and a. These standards define the over the air interface which is between wireless clients or between the base station and the wireless client. Basically, these guidelines do optimize short range and high speed communications. (Cirronet 2002, p 69). Industrial control systems in general encompasses several types of control systems that includes programmable logic controllers (PLC), distributed control system (DCS) and the supervisory control and data acquisition system(SCADA). This report looks into this systems and how other wireless configurations can be tailored to fit timely industrial control. PLCs, SCADA and DCS System The SCADA systems are involved in areas that are highly distributed therefore being used to control geographically dispersed assert which are scattered over thousands of kilometers (Bertocco et al 2007, pp 3). SCADA have a data acquisition that is centralized and the control is very critical to the system operation. Monitoring and controlling of field sites using SCADA is via long distance communications networks both wireless and wired. A wireless network in these cases includes use of satellites. Using the centralized monitoring and evaluation, SCADA systems are able to monitor and control the field sites over a very long communication networks that may include monitoring and processing status data. Using the information that has been received from the remote stations, the operator-driven or the automated supervisory commands may be pushed to the remote station control devices that are commonly referred to as field devices. These field devices would then be used to control the devices in the remote field using programmed commands. The DCS systems on the other hand are used to control the industrial process like the automotive production, food and chemical plants, waste treatment and water treatment plants, oil refineries plants and electrical power generation (Willig & Kubisch 2002 pp. 45). To effectively control a plant, the DCS are integrated via the control architecture that contains supervisory level that is able to oversee multiple and integrated subsystems which are responsible for controlling a localized process. The process and product control are basically achieved through use feed forward and feedback control loops with the main products and the process conditions being maintained around a desired set point automatically. In order to achieve the desired process and product tolerance, around a specific point, the PLCs are used and the derivative, integral and proportional settings of the PLC set in a way that they can provide desired tolerance and the rate of self correction during the process upsets. Therefore, DCS are extensively used in the industries and the distance of control is limited to the square area of the set industry. PLC on the other hand are solid state devices based which are computer based and are used throughout the DCS and SCADA systems and are mainly the primary components in the small control system configurations that are used to give the operational control of the discrete processes like the control in the power plants or in automobile assembly lines (Stouffer, Falco & Scarfone 2006, pp. 35) Bluetooth Bluetooth does refer to the short range radio technology which aims to simplify the communication between the electrical devices. Bluetooth is mainly used in the telecom market, but its application could be advanced to the level of industrial application in real time control of systems. The initial design for Bluetooth technology was not designed for real-time application. Instead it was designed to replace cables, ad hoc networks and be able to transmit voice and data. In the industrial control however the communication are typically short but would demand high level of security while giving very fast transfer (Stouffer, Falco & Scarfone 2006). Therefore, this would require the support that enhances quality service and the ability to deal with the external disturbances. Today, Bluetooth technology does have ARQ scheme, with the exception of the voice packets, which would make transfer of deterministic data difficult. However, upgrading the Bluetooth through implementation of industrial standards can enhance its usability in real-time considerations. The upgrade would bring into place a faster means of transmission technology though it would come with less reliability. Another issue that could improve the suitability of WLAN in the industrial application would be in the design of application of a predictive controller that is able to deal with delays that are varying or some control algorithm which are able to handle packet timeout or missing data.( Lucan 2006, pp. 2) Wireless LANS The wireless personal area network (WPAN) is used to interconnect small devices that are of relatively within small area (Simacek 2002 pp. 35). Use of WiFi, infrared and Bluetooth radio in sending small amount of data between laptops and mobile phones. However, this wireless technology is not advanced to the level that it can be used in industrial control. This form of network does not meet the IEEE 802.11 standards for the industrial control since it has very short time response and the amount of data that can be transmitted at the same time is minimal. However, in industrial set up where the rate of transmission and amount of data transmitted is not of concern, then Wireless PAN can be perfectly fit as the form of control. The wireless local area network WLAN is an advanced from WPAN. This network has the capability of linking more than two devices using a wireless distribution method and further be able to provide a connection through an access point to the internet. As a result, the user is given the freedom of moving around yet be connected to the network. This network does meet the IEEE 802.11 standards and can therefore be used for industrial control. However, according to Stouffer, Falco & Scarfone(2006, pp. 99), even though the wired equivalency policy and Wi-Fi protected access are enacted in the standard, security is still a problem in this network whenever more than two systems are communicating at the same time. The wireless mesh network (WMN) is a wireless communication network which is consists of radio nodes that are organized in a mesh topology. It can be seen a special form of wireless ad-hoc network. In terms of offering reliable communication in terms of timely communication, mesh network would be reliable (Bianch 2000, pp 86). Moreover, the network offers redundancy meaning that in industrial control, it would be able to follow up on whether a control signal is being obeyed. In addition, when one node fails to operate, the rest of the nodes would still offer communication either directly or through the intermediate nodes. Since the mesh network is more organized and configured, it is possible to deploy security measures in the network an offer a cost effective control over a large geographic area. In addition, an ad-hoc network is formed whenever the wireless devices do come in the range of communication of each other. The wireless metropolitan area network (WMAN) that connects local area networks wirelessly. In this case, whenever timely communication would be required for control over a wide area may be thousands of kilometers, and then this is the perfect network. The largest type of wireless network in this category is the Worldwide Interoperability for Microwave Access (WiMAX). However, timely control cannot be guaranteed in these kinds of systems since time is lost in interfacing the LAN networks. Moreover, it is prone to insecurity and loss of data. Broadband Wireless Access The broadband wireless access does provide a high rate of wireless communications that is between fixed points of access or via multiple terminals. Rappaport (2002, pp. 24) observes that the initial design of these types of systems was proposed for supporting video services that are interactive to homes. However, their application went on and shifted to that of giving fast data speed access via the internet. Today this wireless technology is able to provide a spectrum of up to 28 GHz for the local distribution systems. Since the system is able to handle large amount of data, it is mature enough to be used for industrial control system that requires large amount of signals to be transmitted at the same time. However, the system design would need to emphasis on data security and speed of the interface. Paging system The paging systems are used to transmit short paging messages in a simultaneous manner from base stations or satellites that are tall (Andersson, 2002, pp. 6). By the use of torrential transmitters, these systems can be able to transmit within a localized geographic area like of the industrial set up. This kind of wireless network does not require any form of routing functions or location management because the paging message is broadcasted in the entire coverage area. In the industrial set up, this technology would best suit multiple control systems where the a signal is sent to control multiple systems at the same time and more specifically open loop control that works simultaneously. Many industrial set up have feed uses feedback control and the control does not happen at the same simultaneously. Paging systems can however be interfaced with other networks to enable timely industrial that offers more flexibilities. Limitations of Wireless Network Overall, the architecture of the wireless systems has the resources as the major limitations to the full enactment in the industrial control applications (Zhao 2011, pp. 58). For the design of such a system, the devices that would be needed would face the challenges such as constrainable energy capacity, bandwidth limitation, processing power and memory limitations. The hardware would require that the system support the processing module and the operation system, the network protocol, and also be able to handle the control and the data processing algorithms (Boqi 2007, pp. 8). For this reason, selecting the type of the microprocessor to use in this kind of design is very important. Ideal type of microprocessor would be that which has very large memory, consumes very low amount of power, energy efficient and has powerful computation capability. The kind of bandwidth that is handled by these networks would be required to be such that the data aggregation is of good technique and that is able to achieve the required amount of network capacity within the limited band width. Through aggregating of multiple packets into one packet it would be possible with reduced overhead for each packet. Similar information or data could be aggregated through use of certain functions like average, maxima, minima or suppression. Stouffer, Falco & Scarfone (2006 pp. 96) observes that the challenge of power consumption is a performance limiting factor for the wireless systems. Where different wireless systems are used, there would be the need for different power consumptions would be used. If one fails, then there is the risk of the entire or part of the system failing. Moreover, the wireless nodes do operate with small duty cycles that can be able to conserve power meaning they may remain to be inactive as long as possible. Again, varying battery power at the wireless terminals may result to the quality of the signal that is transmitted varying. Conclusion The wireless technology does offer a promising future in terms of industrial application in the industries. Presently, the technology has very wide application that offers significant advantages over the wired network systems. However, the technology is not fully considered mature enough for providing process and industrial control. The main constrains to this technology is the challenges that are posed once the systems have been implemented. In this report, we have looked on different network configuration networks and how they can be implemented to meet the demand of the industrial control. The reports have also looked onto the ways through which the networks may be implemented in order to meet the demand for industrial control. References Cirronet, 2002, ‘Wireless Communications for Industrial Application’, White paper, Vol. 1, no.1, pp. 68-73. Boqi, H, 2007, ‘Application of Industrial Wireless Technology in Zhenhai Refinery Ethylene Pipeline Project’, Honeywell Process Solutions, Vol. 1, no. 3, pp. 1-10. Lucan, V, Simacek, P, Seppala, J & Koivisto, H 2006, ‘Bluetooth and Wireless LAN Applicability for Real-time Control,’ Wireless networks and their Industrial control, Vol. 21, no. 6, pp. 1-65. Stouffer, K, Falco, J & Scarfone, K 2006, W ‘Recommendations of the National Institute of Standard and Technology,’ Guide to Industrial Control System(ICS) Security, Vol. 2, no. 2, pp. 96-120. Goldsmith, A 2005, Wireless Communications, Cambridge University Press, Cambridge. Bertocco, M, Gamba, G, Sona, A & Vitturi, S 2007, ‘ Performance Measurement of CSMA/CA-Based Wireless Sensor Networks for Industrial Applications’, IEEE Instrumentation and Measurement, Vol. 6, no. 4, pp.1-4. Stouffer, K, Falco, J & Scarfone, K 2006, Computer Security, , Gaithersbug. Zhao, G 2011, ‘Wireless Sensor Networks for Industrial Process Monitoring and Control: A Survey’, Network Protocols and Algorithms, Vol. 3, no. 1, pp. 46-63 . Simacek , P 2002 Real-time Control Using Wireless Local Area Network, University of Technology, Finland Simacek, P., Lucan, V., Seppala J & Koivisto, H. 2001 ‘Remote real-time control working over a wireless network.’ Cybernetic and Informatics, Vol. 7, no. 23, pp. 111-180. Andersson, M 2002, ‘Bluetooth for Industry’, The Industrial Ethernet Book Vol. 11, no. 1, pp. 5-11. Stouffer, K, Falco, J, Scarfone, K 2006, W ‘Recommendations of the National Institute of Standard and Technology,’ Guide to Industrial Control System(ICS) Security, Vol. 2, no. 2, pp. 96-120. Willig A & Kubisch, M 2002 ‘ Measurements of a wireless link in an industrial environment using an IEEE 802.11-compiant physical layer, IEEE Trans. On Ind. Electr. Vol. 49, no. 6, pp.1-44. Bianchi G 2000 ‘Performance analysis of the IEEE 802.11 Distributed Coordination Function’, IEEE Journal on Selected Areas in Communication. Vol. 18, no. 3, pp.1-44. Willig, A, Matheus, K.Wolisz: “Wireless Technology in Industrial Networks”, Proceeding of the IEEE, Vol. 93, no.5 pp. 120-150. Rappaport, T 2002 Wireless Communication: Principles and Practice, 2nd ed. Prentice Hall Read More