See also
* Industrial Control Systems
* Lonworks
* Modbus
* Telemetry
[edit] References
1. ^ Basic SCADA Animations
2. ^ Donald Wallace (2003-09-01). "How to put SCADA on the Internet". Control Engineering. http://www.controleng.com/article/CA321065.html. Retrieved 2008-05-30. (Note: Donald Wallace is COO of M2M Data Corporation, a SCADA vendor.)
3. ^ D. Maynor and R. Graham. "SCADA Security and Terrorism: We're Not Crying Wolf". http://www.blackhat.com/presentations/bh-federal-06/BH-Fed-06-Maynor-Graham-up.pdf.
4. ^ Robert Lemos (2006-07-26). "SCADA system makers pushed toward security". SecurityFocus. http://www.securityfocus.com/news/11402. Retrieved 2007-05-09.
5. ^ "S4 2008 Agenda". http://www.digitalbond.com/wp-content/uploads/2007/10/S4_2008_Agenda.pdf.
6. ^ "SCADA Security - Generic Electric Grid Malware Design". http://www.c4-security.com/SCADA%20Security%20-%20Generic%20Electric%20Grid%20Malware%20Design%20-%20SyScan08.pps.
7. ^ KEMA, Inc. (November 2006). Substation Communications: Enabler of Automation / An Assessment of Communications Technologies. UTC - United Telecom Council. p. 3–21.
[edit] External links
* UK SCADA security guidelines
* BBC NEWS | Technology | Spies 'infiltrate US power grid'
Thursday, July 15, 2010
Security issues
Security issues
The move from proprietary technologies to more standardized and open solutions together with the increased number of connections between SCADA systems and office networks and the Internet has made them more vulnerable to attacks - see references. Consequently, the security of SCADA-based systems has come into question as they are increasingly seen as extremely vulnerable to cyberwarfare/cyberterrorism attacks.[3][4]
In particular, security researchers are concerned about:
* the lack of concern about security and authentication in the design, deployment and operation of existing SCADA networks
* the belief that SCADA systems have the benefit of security through obscurity through the use of specialized protocols and proprietary interfaces
* the belief that SCADA networks are secure because they are physically secured
* the belief that SCADA networks are secure because they are disconnected from the Internet
SCADA systems are used to control and monitor physical processes, examples of which are transmission of electricity, transportation of gas and oil in pipelines, water distribution, traffic lights, and other systems used as the basis of modern society. The security of these SCADA systems is important because compromise or destruction of these systems would impact multiple areas of society far removed from the original compromise. For example, a blackout caused by a compromised electrical SCADA system would cause financial losses to all the customers that received electricity from that source. How security will affect legacy SCADA and new deployments remains to be seen.
There are two distinct threats to a modern SCADA system. First is the threat of unauthorized access to the control software, whether it be human access or changes induced intentionally or accidentally by virus infections and other software threats residing on the control host machine. Second is the threat of packet access to the network segments hosting SCADA devices. In many cases, there is rudimentary or no security on the actual packet control protocol, so anyone who can send packets to the SCADA device can control it. In many cases SCADA users assume that a VPN is sufficient protection and are unaware that physical access to SCADA-related network jacks and switches provides the ability to totally bypass all security on the control software and fully control those SCADA networks. These kinds of physical access attacks bypass firewall and VPN security and are best addressed by endpoint-to-endpoint authentication and authorization such as are commonly provided in the non-SCADA world by in-device SSL or other cryptographic techniques.
Many vendors of SCADA and control products have begun to address these risks in a basic sense by developing lines of specialized industrial firewall and VPN solutions for TCP/IP-based SCADA networks. Additionally, application whitelisting solutions are being implemented because of their ability to prevent malware and unauthorized application changes without the performance impacts of traditional antivirus scans[citation needed]. Also, the ISA Security Compliance Institute (ISCI) is emerging to formalize SCADA security testing starting as soon as 2009. ISCI is conceptually similar to private testing and certification that has been performed by vendors since 2007. Eventually, standards being defined by ISA99 WG4 will supersede the initial industry consortia efforts, but probably not before 2011 .
The increased interest in SCADA vulnerabilities has resulted in vulnerability researchers discovering vulnerabilities in commercial SCADA software and more general offensive SCADA techniques presented to the general security community.[5][6] In electric and gas utility SCADA systems, the vulnerability of the large installed base of wired and wireless serial communications links is addressed in some cases by applying bump-in-the-wire devices that employ authentication and Advanced Encryption Standard encryption rather than replacing all existing nodes.[7]
The move from proprietary technologies to more standardized and open solutions together with the increased number of connections between SCADA systems and office networks and the Internet has made them more vulnerable to attacks - see references. Consequently, the security of SCADA-based systems has come into question as they are increasingly seen as extremely vulnerable to cyberwarfare/cyberterrorism attacks.[3][4]
In particular, security researchers are concerned about:
* the lack of concern about security and authentication in the design, deployment and operation of existing SCADA networks
* the belief that SCADA systems have the benefit of security through obscurity through the use of specialized protocols and proprietary interfaces
* the belief that SCADA networks are secure because they are physically secured
* the belief that SCADA networks are secure because they are disconnected from the Internet
SCADA systems are used to control and monitor physical processes, examples of which are transmission of electricity, transportation of gas and oil in pipelines, water distribution, traffic lights, and other systems used as the basis of modern society. The security of these SCADA systems is important because compromise or destruction of these systems would impact multiple areas of society far removed from the original compromise. For example, a blackout caused by a compromised electrical SCADA system would cause financial losses to all the customers that received electricity from that source. How security will affect legacy SCADA and new deployments remains to be seen.
There are two distinct threats to a modern SCADA system. First is the threat of unauthorized access to the control software, whether it be human access or changes induced intentionally or accidentally by virus infections and other software threats residing on the control host machine. Second is the threat of packet access to the network segments hosting SCADA devices. In many cases, there is rudimentary or no security on the actual packet control protocol, so anyone who can send packets to the SCADA device can control it. In many cases SCADA users assume that a VPN is sufficient protection and are unaware that physical access to SCADA-related network jacks and switches provides the ability to totally bypass all security on the control software and fully control those SCADA networks. These kinds of physical access attacks bypass firewall and VPN security and are best addressed by endpoint-to-endpoint authentication and authorization such as are commonly provided in the non-SCADA world by in-device SSL or other cryptographic techniques.
Many vendors of SCADA and control products have begun to address these risks in a basic sense by developing lines of specialized industrial firewall and VPN solutions for TCP/IP-based SCADA networks. Additionally, application whitelisting solutions are being implemented because of their ability to prevent malware and unauthorized application changes without the performance impacts of traditional antivirus scans[citation needed]. Also, the ISA Security Compliance Institute (ISCI) is emerging to formalize SCADA security testing starting as soon as 2009. ISCI is conceptually similar to private testing and certification that has been performed by vendors since 2007. Eventually, standards being defined by ISA99 WG4 will supersede the initial industry consortia efforts, but probably not before 2011 .
The increased interest in SCADA vulnerabilities has resulted in vulnerability researchers discovering vulnerabilities in commercial SCADA software and more general offensive SCADA techniques presented to the general security community.[5][6] In electric and gas utility SCADA systems, the vulnerability of the large installed base of wired and wireless serial communications links is addressed in some cases by applying bump-in-the-wire devices that employ authentication and Advanced Encryption Standard encryption rather than replacing all existing nodes.[7]
Networked
Third generation: "Networked"
These are the current generation SCADA systems which use open system architecture rather than a vendor-controlled proprietary environment. The SCADA system utilizes open standards and protocols, thus distributing functionality across a WAN rather than a LAN. It is easier to connect third party peripheral devices like printers, disk drives, and tape drives due to the use of open architecture. WAN protocols such as Internet Protocol (IP) are used for communication between the master station and communications equipment. Due to the usage of standard protocols and the fact that many networked SCADA systems are accessible from the Internet, the systems are potentially vulnerable to remote cyber-attacks. On the other hand, the usage of standard protocols and security techniques means that standard security improvements are applicable to the SCADA systems, assuming they receive timely maintenance and updates.
[edit] Trends in SCADA
There is a trend for PLC and HMI/SCADA software to be more "mix-and-match". In the mid 1990s, the typical DAQ I/O manufacturer supplied equipment that communicated using proprietary protocols over a suitable-distance carrier like RS-485. End users who invested in a particular vendor's hardware solution often found themselves restricted to a limited choice of equipment when requirements changed (e.g. system expansions or performance improvement). To mitigate such problems, open communication protocols such as IEC IEC 60870-5-101 or 104, IEC 61850, DNP3 serial, and DNP3 LAN/WAN became increasingly popular among SCADA equipment manufacturers and solution providers alike. Open architecture SCADA systems enabled users to mix-and-match products from different vendors to develop solutions that were better than those that could be achieved when restricted to a single vendor's product offering.
Towards the late 1990s, the shift towards open communications continued with individual I/O manufacturers as well, who adopted open message structures such as Modbus RTU and Modbus ASCII (originally both developed by Modicon) over RS-485. By 2000, most I/O makers offered completely open interfacing such as Modbus TCP over Ethernet and IP.
The North American Electric Reliability Corporation (NERC) has specified that electrical system data should be time-tagged to the nearest millisecond. Electrical system SCADA systems provide this Sequence of events recorder function, using Radio clocks to synchronize the RTU or distributed RTU clocks.
SCADA systems are coming in line with standard networking technologies. Ethernet and TCP/IP based protocols are replacing the older proprietary standards. Although certain characteristics of frame-based network communication technology (determinism, synchronization, protocol selection, environment suitability) have restricted the adoption of Ethernet in a few specialized applications, the vast majority of markets have accepted Ethernet networks for HMI/SCADA.
With the emergence of software as a service in the broader software industry, a few vendors have begun offering application specific SCADA systems hosted on remote platforms over the Internet. This removes the need to install and commission systems at the end-user's facility and takes advantage of security features already available in Internet technology, VPNs and SSL. Some concerns include security,[2] Internet connection reliability, and latency.
SCADA systems are becoming increasingly ubiquitous. Thin clients, web portals, and web based products are gaining popularity with most major vendors. The increased convenience of end users viewing their processes remotely introduces security considerations. While these considerations are already considered solved in other sectors of Internet services, not all entities responsible for deploying SCADA systems have understood the changes in accessibility and threat scope implicit in connecting a system to the Internet.
These are the current generation SCADA systems which use open system architecture rather than a vendor-controlled proprietary environment. The SCADA system utilizes open standards and protocols, thus distributing functionality across a WAN rather than a LAN. It is easier to connect third party peripheral devices like printers, disk drives, and tape drives due to the use of open architecture. WAN protocols such as Internet Protocol (IP) are used for communication between the master station and communications equipment. Due to the usage of standard protocols and the fact that many networked SCADA systems are accessible from the Internet, the systems are potentially vulnerable to remote cyber-attacks. On the other hand, the usage of standard protocols and security techniques means that standard security improvements are applicable to the SCADA systems, assuming they receive timely maintenance and updates.
[edit] Trends in SCADA
There is a trend for PLC and HMI/SCADA software to be more "mix-and-match". In the mid 1990s, the typical DAQ I/O manufacturer supplied equipment that communicated using proprietary protocols over a suitable-distance carrier like RS-485. End users who invested in a particular vendor's hardware solution often found themselves restricted to a limited choice of equipment when requirements changed (e.g. system expansions or performance improvement). To mitigate such problems, open communication protocols such as IEC IEC 60870-5-101 or 104, IEC 61850, DNP3 serial, and DNP3 LAN/WAN became increasingly popular among SCADA equipment manufacturers and solution providers alike. Open architecture SCADA systems enabled users to mix-and-match products from different vendors to develop solutions that were better than those that could be achieved when restricted to a single vendor's product offering.
Towards the late 1990s, the shift towards open communications continued with individual I/O manufacturers as well, who adopted open message structures such as Modbus RTU and Modbus ASCII (originally both developed by Modicon) over RS-485. By 2000, most I/O makers offered completely open interfacing such as Modbus TCP over Ethernet and IP.
The North American Electric Reliability Corporation (NERC) has specified that electrical system data should be time-tagged to the nearest millisecond. Electrical system SCADA systems provide this Sequence of events recorder function, using Radio clocks to synchronize the RTU or distributed RTU clocks.
SCADA systems are coming in line with standard networking technologies. Ethernet and TCP/IP based protocols are replacing the older proprietary standards. Although certain characteristics of frame-based network communication technology (determinism, synchronization, protocol selection, environment suitability) have restricted the adoption of Ethernet in a few specialized applications, the vast majority of markets have accepted Ethernet networks for HMI/SCADA.
With the emergence of software as a service in the broader software industry, a few vendors have begun offering application specific SCADA systems hosted on remote platforms over the Internet. This removes the need to install and commission systems at the end-user's facility and takes advantage of security features already available in Internet technology, VPNs and SSL. Some concerns include security,[2] Internet connection reliability, and latency.
SCADA systems are becoming increasingly ubiquitous. Thin clients, web portals, and web based products are gaining popularity with most major vendors. The increased convenience of end users viewing their processes remotely introduces security considerations. While these considerations are already considered solved in other sectors of Internet services, not all entities responsible for deploying SCADA systems have understood the changes in accessibility and threat scope implicit in connecting a system to the Internet.
SCADA architectures
SCADA architectures
The United States Army's Training Manual 5-601 covers "SCADA Systems for C4ISR Facilities".
SCADA systems have evolved through 3 generations as follows:[citation needed]
[edit] First generation: "Monolithic"
In the first generation, computing was done by mainframe systems. Networks didn’t exist at the time SCADA was developed. Thus SCADA systems were independent systems with no connectivity to other systems. Wide Area Networks were later designed by RTU vendors to communicate with the RTU. The communication protocols used were often proprietary at that time. The first-generation SCADA system was redundant since a back-up mainframe system was connected at the bus level and was used in the event of failure of the primary mainframe system.
[edit] Second generation: "Distributed"
The processing was distributed across multiple stations which were connected through a LAN and they shared information in real time. Each station was responsible for a particular task thus making the size and cost of each station less than the one used in First Generation. The network protocols used were still mostly proprietary, which led to significant security problems for any SCADA system that received attention from a hacker. Since the protocols were proprietary, very few people beyond the developers and hackers knew enough to determine how secure a SCADA installation was. Since both parties had vested interests in keeping security issues quiet, the security of a SCADA installation was often badly overestimated, if it was considered at all.
The United States Army's Training Manual 5-601 covers "SCADA Systems for C4ISR Facilities".
SCADA systems have evolved through 3 generations as follows:[citation needed]
[edit] First generation: "Monolithic"
In the first generation, computing was done by mainframe systems. Networks didn’t exist at the time SCADA was developed. Thus SCADA systems were independent systems with no connectivity to other systems. Wide Area Networks were later designed by RTU vendors to communicate with the RTU. The communication protocols used were often proprietary at that time. The first-generation SCADA system was redundant since a back-up mainframe system was connected at the bus level and was used in the event of failure of the primary mainframe system.
[edit] Second generation: "Distributed"
The processing was distributed across multiple stations which were connected through a LAN and they shared information in real time. Each station was responsible for a particular task thus making the size and cost of each station less than the one used in First Generation. The network protocols used were still mostly proprietary, which led to significant security problems for any SCADA system that received attention from a hacker. Since the protocols were proprietary, very few people beyond the developers and hackers knew enough to determine how secure a SCADA installation was. Since both parties had vested interests in keeping security issues quiet, the security of a SCADA installation was often badly overestimated, if it was considered at all.
Communication infrastructure and methods
SCADA systems have traditionally used combinations of radio and direct serial or modem connections to meet communication requirements, although Ethernet and IP over SONET / SDH is also frequently used at large sites such as railways and power stations. The remote management or monitoring function of a SCADA system is often referred to as telemetry.
This has also come under threat with some customers wanting SCADA data to travel over their pre-established corporate networks or to share the network with other applications. The legacy of the early low-bandwidth protocols remains, though. SCADA protocols are designed to be very compact and many are designed to send information to the master station only when the master station polls the RTU. Typical legacy SCADA protocols include Modbus RTU, RP-570, Profibus and Conitel. These communication protocols are all SCADA-vendor specific but are widely adopted and used. Standard protocols are IEC 60870-5-101 or 104, IEC 61850 and DNP3. These communication protocols are standardized and recognized by all major SCADA vendors. Many of these protocols now contain extensions to operate over TCP/IP. It is good security engineering practice to avoid connecting SCADA systems to the Internet so the attack surface is reduced.
RTUs and other automatic controller devices were being developed before the advent of industry wide standards for interoperability. The result is that developers and their management created a multitude of control protocols. Among the larger vendors, there was also the incentive to create their own protocol to "lock in" their customer base. A list of automation protocols is being compiled here.
Recently, OLE for Process Control (OPC) has become a widely accepted solution for intercommunicating different hardware and software, allowing communication even between devices originally not intended to be part of an industrial network.
This has also come under threat with some customers wanting SCADA data to travel over their pre-established corporate networks or to share the network with other applications. The legacy of the early low-bandwidth protocols remains, though. SCADA protocols are designed to be very compact and many are designed to send information to the master station only when the master station polls the RTU. Typical legacy SCADA protocols include Modbus RTU, RP-570, Profibus and Conitel. These communication protocols are all SCADA-vendor specific but are widely adopted and used. Standard protocols are IEC 60870-5-101 or 104, IEC 61850 and DNP3. These communication protocols are standardized and recognized by all major SCADA vendors. Many of these protocols now contain extensions to operate over TCP/IP. It is good security engineering practice to avoid connecting SCADA systems to the Internet so the attack surface is reduced.
RTUs and other automatic controller devices were being developed before the advent of industry wide standards for interoperability. The result is that developers and their management created a multitude of control protocols. Among the larger vendors, there was also the incentive to create their own protocol to "lock in" their customer base. A list of automation protocols is being compiled here.
Recently, OLE for Process Control (OPC) has become a widely accepted solution for intercommunicating different hardware and software, allowing communication even between devices originally not intended to be part of an industrial network.
Operational philosophy
Operational philosophy
For some installations, the costs that would result from the control system failing are extremely high. Possibly even lives could be lost. Hardware for some SCADA systems is ruggedized to withstand temperature, vibration, and voltage extremes, but in most critical installations reliability is enhanced by having redundant hardware and communications channels, up to the point of having multiple fully equipped control centres. A failing part can be quickly identified and its functionality automatically taken over by backup hardware. A failed part can often be replaced without interrupting the process. The reliability of such systems can be calculated statistically and is stated as the mean time to failure, which is a variant of mean time between failures. The calculated mean time to failure of such high reliability systems can be on the order of centuries.
For some installations, the costs that would result from the control system failing are extremely high. Possibly even lives could be lost. Hardware for some SCADA systems is ruggedized to withstand temperature, vibration, and voltage extremes, but in most critical installations reliability is enhanced by having redundant hardware and communications channels, up to the point of having multiple fully equipped control centres. A failing part can be quickly identified and its functionality automatically taken over by backup hardware. A failed part can often be replaced without interrupting the process. The reliability of such systems can be calculated statistically and is stated as the mean time to failure, which is a variant of mean time between failures. The calculated mean time to failure of such high reliability systems can be on the order of centuries.
Remote Terminal Unit (RTU)
The RTU connects to physical equipment. Typically, an RTU converts the electrical signals from the equipment to digital values such as the open/closed status from a switch or a valve, or measurements such as pressure, flow, voltage or current. By converting and sending these electrical signals out to equipment the RTU can control equipment, such as opening or closing a switch or a valve, or setting the speed of a pump.
[edit] Supervisory Station
The term "Supervisory Station" refers to the servers and software responsible for communicating with the field equipment (RTUs, PLCs, etc), and then to the HMI software running on workstations in the control room, or elsewhere. In smaller SCADA systems, the master station may be composed of a single PC. In larger SCADA systems, the master station may include multiple servers, distributed software applications, and disaster recovery sites. To increase the integrity of the system the multiple servers will often be configured in a dual-redundant or hot-standby formation providing continuous control and monitoring in the event of a server failure.
[edit] Supervisory Station
The term "Supervisory Station" refers to the servers and software responsible for communicating with the field equipment (RTUs, PLCs, etc), and then to the HMI software running on workstations in the control room, or elsewhere. In smaller SCADA systems, the master station may be composed of a single PC. In larger SCADA systems, the master station may include multiple servers, distributed software applications, and disaster recovery sites. To increase the integrity of the system the multiple servers will often be configured in a dual-redundant or hot-standby formation providing continuous control and monitoring in the event of a server failure.
Hardware solutions
SCADA solutions often have Distributed Control System (DCS) components. Use of "smart" RTUs or PLCs, which are capable of autonomously executing simple logic processes without involving the master computer, is increasing. A functional block programming language, IEC 61131-3 (Ladder Logic), is frequently used to create programs which run on these RTUs and PLCs. Unlike a procedural language such as the C programming language or FORTRAN, IEC 61131-3 has minimal training requirements by virtue of resembling historic physical control arrays. This allows SCADA system engineers to perform both the design and implementation of a program to be executed on an RTU or PLC. A Programmable automation controller (PAC) is a compact controller that combines the features and capabilities of a PC-based control system with that of a typical PLC. PACs are deployed in SCADA systems to provide RTU and PLC functions. In many electrical substation SCADA applications, "distributed RTUs" use information processors or station computers to communicate with protective relays, PACS, and other devices for I/O, and communicate with the SCADA master in lieu of a traditional RTU.
Since about 1998, virtually all major PLC manufacturers have offered integrated HMI/SCADA systems, many of them using open and non-proprietary communications protocols. Numerous specialized third-party HMI/SCADA packages, offering built-in compatibility with most major PLCs, have also entered the market, allowing mechanical engineers, electrical engineers and technicians to configure HMIs themselves, without the need for a custom-made program written by a software developer.
Since about 1998, virtually all major PLC manufacturers have offered integrated HMI/SCADA systems, many of them using open and non-proprietary communications protocols. Numerous specialized third-party HMI/SCADA packages, offering built-in compatibility with most major PLCs, have also entered the market, allowing mechanical engineers, electrical engineers and technicians to configure HMIs themselves, without the need for a custom-made program written by a software developer.
Human Machine Interface
Human Machine Interface
Typical Basic SCADA Animations [1]
A Human-Machine Interface or HMI is the apparatus which presents process data to a human operator, and through which the human operator controls the process.
An HMI is usually linked to the SCADA system's databases and software programs, to provide trending, diagnostic data, and management information such as scheduled maintenance procedures, logistic information, detailed schematics for a particular sensor or machine, and expert-system troubleshooting guides.
The HMI system usually presents the information to the operating personnel graphically, in the form of a mimic diagram. This means that the operator can see a schematic representation of the plant being controlled. For example, a picture of a pump connected to a pipe can show the operator that the pump is running and how much fluid it is pumping through the pipe at the moment. The operator can then switch the pump off. The HMI software will show the flow rate of the fluid in the pipe decrease in real time. Mimic diagrams may consist of line graphics and schematic symbols to represent process elements, or may consist of digital photographs of the process equipment overlain with animated symbols.
The HMI package for the SCADA system typically includes a drawing program that the operators or system maintenance personnel use to change the way these points are represented in the interface. These representations can be as simple as an on-screen traffic light, which represents the state of an actual traffic light in the field, or as complex as a multi-projector display representing the position of all of the elevators in a skyscraper or all of the trains on a railway.
An important part of most SCADA implementations is alarm handling. The system monitors whether certain alarm conditions are satisfied, to determine when an alarm event has occurred. Once an alarm event has been detected, one or more actions are taken (such as the activation of one or more alarm indicators, and perhaps the generation of email or text messages so that management or remote SCADA operators are informed). In many cases, a SCADA operator may have to acknowledge the alarm event; this may deactivate some alarm indicators, whereas other indicators remain active until the alarm conditions are cleared. Alarm conditions can be explicit - for example, an alarm point is a digital status point that has either the value NORMAL or ALARM that is calculated by a formula based on the values in other analogue and digital points - or implicit: the SCADA system might automatically monitor whether the value in an analogue point lies outside high and low limit values associated with that point. Examples of alarm indicators include a siren, a pop-up box on a screen, or a coloured or flashing area on a screen (that might act in a similar way to the "fuel tank empty" light in a car); in each case, the role of the alarm indicator is to draw the operator's attention to the part of the system 'in alarm' so that appropriate action can be taken. In designing SCADA systems, care is needed in coping with a cascade of alarm events occurring in a short time, otherwise the underlying cause (which might not be the earliest event detected) may get lost in the noise. Unfortunately, when used as a noun, the word 'alarm' is used rather loosely in the industry; thus, depending on context it might mean an alarm point, an alarm indicator, or an alarm event.
Typical Basic SCADA Animations [1]
A Human-Machine Interface or HMI is the apparatus which presents process data to a human operator, and through which the human operator controls the process.
An HMI is usually linked to the SCADA system's databases and software programs, to provide trending, diagnostic data, and management information such as scheduled maintenance procedures, logistic information, detailed schematics for a particular sensor or machine, and expert-system troubleshooting guides.
The HMI system usually presents the information to the operating personnel graphically, in the form of a mimic diagram. This means that the operator can see a schematic representation of the plant being controlled. For example, a picture of a pump connected to a pipe can show the operator that the pump is running and how much fluid it is pumping through the pipe at the moment. The operator can then switch the pump off. The HMI software will show the flow rate of the fluid in the pipe decrease in real time. Mimic diagrams may consist of line graphics and schematic symbols to represent process elements, or may consist of digital photographs of the process equipment overlain with animated symbols.
The HMI package for the SCADA system typically includes a drawing program that the operators or system maintenance personnel use to change the way these points are represented in the interface. These representations can be as simple as an on-screen traffic light, which represents the state of an actual traffic light in the field, or as complex as a multi-projector display representing the position of all of the elevators in a skyscraper or all of the trains on a railway.
An important part of most SCADA implementations is alarm handling. The system monitors whether certain alarm conditions are satisfied, to determine when an alarm event has occurred. Once an alarm event has been detected, one or more actions are taken (such as the activation of one or more alarm indicators, and perhaps the generation of email or text messages so that management or remote SCADA operators are informed). In many cases, a SCADA operator may have to acknowledge the alarm event; this may deactivate some alarm indicators, whereas other indicators remain active until the alarm conditions are cleared. Alarm conditions can be explicit - for example, an alarm point is a digital status point that has either the value NORMAL or ALARM that is calculated by a formula based on the values in other analogue and digital points - or implicit: the SCADA system might automatically monitor whether the value in an analogue point lies outside high and low limit values associated with that point. Examples of alarm indicators include a siren, a pop-up box on a screen, or a coloured or flashing area on a screen (that might act in a similar way to the "fuel tank empty" light in a car); in each case, the role of the alarm indicator is to draw the operator's attention to the part of the system 'in alarm' so that appropriate action can be taken. In designing SCADA systems, care is needed in coping with a cascade of alarm events occurring in a short time, otherwise the underlying cause (which might not be the earliest event detected) may get lost in the noise. Unfortunately, when used as a noun, the word 'alarm' is used rather loosely in the industry; thus, depending on context it might mean an alarm point, an alarm indicator, or an alarm event.
SCADA schematic
SCADA schematic overview-s.svg
Data acquisition begins at the RTU or PLC level and includes meter readings and equipment status reports that are communicated to SCADA as required. Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal RTU (PLC) controls. Data may also be fed to a Historian, often built on a commodity Database Management System, to allow trending and other analytical auditing.
SCADA systems typically implement a distributed database, commonly referred to as a tag database, which contains data elements called tags or points. A point represents a single input or output value monitored or controlled by the system. Points can be either "hard" or "soft". A hard point represents an actual input or output within the system, while a soft point results from logic and math operations applied to other points. (Most implementations conceptually remove the distinction by making every property a "soft" point expression, which may, in the simplest case, equal a single hard point.) Points are normally stored as value-timestamp pairs: a value, and the timestamp when it was recorded or calculated. A series of value-timestamp pairs gives the history of that point. It's also common to store additional metadata with tags, such as the path to a field device or PLC register, design time comments, and alarm information.
Data acquisition begins at the RTU or PLC level and includes meter readings and equipment status reports that are communicated to SCADA as required. Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal RTU (PLC) controls. Data may also be fed to a Historian, often built on a commodity Database Management System, to allow trending and other analytical auditing.
SCADA systems typically implement a distributed database, commonly referred to as a tag database, which contains data elements called tags or points. A point represents a single input or output value monitored or controlled by the system. Points can be either "hard" or "soft". A hard point represents an actual input or output within the system, while a soft point results from logic and math operations applied to other points. (Most implementations conceptually remove the distinction by making every property a "soft" point expression, which may, in the simplest case, equal a single hard point.) Points are normally stored as value-timestamp pairs: a value, and the timestamp when it was recorded or calculated. A series of value-timestamp pairs gives the history of that point. It's also common to store additional metadata with tags, such as the path to a field device or PLC register, design time comments, and alarm information.
Systems concepts
The term SCADA usually refers to centralized systems which monitor and control entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country). Most control actions are performed automatically by Remote Terminal Units ("RTUs") or by programmable logic controllers ("PLCs"). Host control functions are usually restricted to basic overriding or supervisory level intervention. For example, a PLC may control the flow of cooling water through part of an industrial process, but the SCADA system may allow operators to change the set points for the flow, and enable alarm conditions, such as loss of flow and high temperature, to be displayed and recorded. The feedback control loop passes through the RTU or PLC, while the SCADA system monitors the overall performance of the loop.
Supervision vs. control
Supervision vs. control
There is, in several industries, considerable confusion over the differences between SCADA systems and distributed control systems (DCS). Generally speaking, a SCADA system usually refers to a system that coordinates, but does not control processes in real time. The discussion on real-time control is muddied somewhat by newer telecommunications technology, enabling reliable, low latency, high speed communications over wide areas. Most differences between SCADA and DCS are culturally determined and can usually be ignored. As communication infrastructures with higher capacity become available, the difference between SCADA and DCS will fade.
There is, in several industries, considerable confusion over the differences between SCADA systems and distributed control systems (DCS). Generally speaking, a SCADA system usually refers to a system that coordinates, but does not control processes in real time. The discussion on real-time control is muddied somewhat by newer telecommunications technology, enabling reliable, low latency, high speed communications over wide areas. Most differences between SCADA and DCS are culturally determined and can usually be ignored. As communication infrastructures with higher capacity become available, the difference between SCADA and DCS will fade.
Common system components
A SCADA System usually consists of the following subsystems:
* A Human-Machine Interface or HMI is the apparatus which presents process data to a human operator, and through this, the human operator monitors and controls the process.
* A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to the process.
* Remote Terminal Units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system.
* Programmable Logic Controller (PLCs) used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs.
* Communication infrastructure connecting the supervisory system to the Remote Terminal Units.
* A Human-Machine Interface or HMI is the apparatus which presents process data to a human operator, and through this, the human operator monitors and controls the process.
* A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to the process.
* Remote Terminal Units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system.
* Programmable Logic Controller (PLCs) used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs.
* Communication infrastructure connecting the supervisory system to the Remote Terminal Units.
SCADA stands
SCADA stands for supervisory control and data acquisition. It generally refers to an industrial control system: a computer system monitoring and controlling a process. The process can be industrial, infrastructure or facility-based as described below:
* Industrial processes include those of manufacturing, production, power generation, fabrication, and refining, and may run in continuous, batch, repetitive, or discrete modes.
* Infrastructure processes may be public or private, and include water treatment and distribution, wastewater collection and treatment, oil and gas pipelines, electrical power transmission and distribution, Wind Farms, civil defense siren systems, and large communication systems.
* Facility processes occur both in public facilities and private ones, including buildings, airports, ships, and space stations. They monitor and control HVAC, access, and energy consumption.
* Industrial processes include those of manufacturing, production, power generation, fabrication, and refining, and may run in continuous, batch, repetitive, or discrete modes.
* Infrastructure processes may be public or private, and include water treatment and distribution, wastewater collection and treatment, oil and gas pipelines, electrical power transmission and distribution, Wind Farms, civil defense siren systems, and large communication systems.
* Facility processes occur both in public facilities and private ones, including buildings, airports, ships, and space stations. They monitor and control HVAC, access, and energy consumption.
Telemetry Software
More Info Catalog
Server Control (DDE)
The NBT Dynamic Data Exchange (DDE) Server Control Software provides the link between your NBT telemetry hardware and the Windows DDE environment and extends the reach of traditional SCADA systems.
SM800 Series PLC
Programmer: Used for configuring and documenting the SM800 Series Programmable Logic Controller online or offline
Visual Graphics Add-On: Designed to eliminate the tedious repetition of programming through the use of function block diagrams. Simply drag and drop the function blocks and draw connection lines.
SR900 Series Configuration
Provides the ability to set all of the SR900 Series Spread Spectrum Wireless Radio parameters and operating modes.
It allows the creation and editing of the Master, Slave or Repeater station configuration files.
Real-Time Monitoring Software (HMI)
Powerful, flexible SCADA, data acquisition and real time telemetry control software package that comes with the DDE server, automated configuration, and point capabilities unmatched by competitors.
Real-Time Report Generating for Excel
Daily, monthly, yearly summary data reports including totals, average, minimum, and maximum are reported at intervals
Historical Database Reporter for Access
Moves time tagged field data into a powerful Microsoft Access Database for analysis and reporting
CSV to Excel Converter Utility
Converts CSV files of events and historical data into an Excel workbook
Server Control (DDE)
The NBT Dynamic Data Exchange (DDE) Server Control Software provides the link between your NBT telemetry hardware and the Windows DDE environment and extends the reach of traditional SCADA systems.
SM800 Series PLC
Programmer: Used for configuring and documenting the SM800 Series Programmable Logic Controller online or offline
Visual Graphics Add-On: Designed to eliminate the tedious repetition of programming through the use of function block diagrams. Simply drag and drop the function blocks and draw connection lines.
SR900 Series Configuration
Provides the ability to set all of the SR900 Series Spread Spectrum Wireless Radio parameters and operating modes.
It allows the creation and editing of the Master, Slave or Repeater station configuration files.
Real-Time Monitoring Software (HMI)
Powerful, flexible SCADA, data acquisition and real time telemetry control software package that comes with the DDE server, automated configuration, and point capabilities unmatched by competitors.
Real-Time Report Generating for Excel
Daily, monthly, yearly summary data reports including totals, average, minimum, and maximum are reported at intervals
Historical Database Reporter for Access
Moves time tagged field data into a powerful Microsoft Access Database for analysis and reporting
CSV to Excel Converter Utility
Converts CSV files of events and historical data into an Excel workbook
Telemetry Hardware Equipment
More Info Catalog
Dependable, long-lasting, cost-effective; that's how customers describe NBT telemetry, SCADA and data acquisition equipment. Whether it is a landfill, remediation, water and wastewater or other industrial application, NBT telemetry equipment will give you years of accurate remote process control.
Available NBT Telemetry Components:
Low Cost Telemetry Equipment for Input/Output Transmission
SM300 Series - Master MTUs and Slave RTUs
Programmable Logic Controllers
SM800 Series - PLC, logging, remote monitoring, control,
and communication capabilities
License-Free, Spread Spectrum Wireless Radios
SR900 Series - Reliable, cost-effective interface for any point-to-
point and/or point-to-multipoint serial equipment operation
TSR900 Series - Same features as the SR900 plus built-in input
output capabilities
Licensed Telemetry Wireless Radios
JSLM - FCC licensed analog telemetry radio
T-SR96 - FCC licensed, refarming-compliant radio modem that
comes in both VHF and UHF frequency bands
Leased Line and Wireless Modems
XMOD15 - 1200 baud analog modem used to interface virtually any
serial RS232 communications to leased line or radio
Telemetry Equipment Accessories
SM800 Expansion Modules
SM800 Display and Entry Module
Antennas
Cables and Connectors
Surge Protection
Cavity Filters
Dependable, long-lasting, cost-effective; that's how customers describe NBT telemetry, SCADA and data acquisition equipment. Whether it is a landfill, remediation, water and wastewater or other industrial application, NBT telemetry equipment will give you years of accurate remote process control.
Available NBT Telemetry Components:
Low Cost Telemetry Equipment for Input/Output Transmission
SM300 Series - Master MTUs and Slave RTUs
Programmable Logic Controllers
SM800 Series - PLC, logging, remote monitoring, control,
and communication capabilities
License-Free, Spread Spectrum Wireless Radios
SR900 Series - Reliable, cost-effective interface for any point-to-
point and/or point-to-multipoint serial equipment operation
TSR900 Series - Same features as the SR900 plus built-in input
output capabilities
Licensed Telemetry Wireless Radios
JSLM - FCC licensed analog telemetry radio
T-SR96 - FCC licensed, refarming-compliant radio modem that
comes in both VHF and UHF frequency bands
Leased Line and Wireless Modems
XMOD15 - 1200 baud analog modem used to interface virtually any
serial RS232 communications to leased line or radio
Telemetry Equipment Accessories
SM800 Expansion Modules
SM800 Display and Entry Module
Antennas
Cables and Connectors
Surge Protection
Cavity Filters
Monday, July 5, 2010
Purchasing Principles
1. Use open standards architecture, i.e. Modbus protocol.
2. Purchase from a reputable, established manufacturer.
3. Equipment must integrate well with existing and future equipment.
4. Equipment must be supportable and well documented.
5. Equipment and system overall must be reliable.
6. Equipment must be easy to use and not cause disruptions to the every day business operation.
7. Equipment must be non-proprietary, proven technology.
EPG equipment uses the open architecture Modbus protocol, is well documented, and will integrate into any existing system. For over 20 years we have been manufacturing dependable, cost-effective process control solutions for thousands of industry professionals. If you have any questions or would like to talk to a Data Acquisition, SCADA or Telemetry hardware specialist, please give us a call at 800-443-7426. We look forward to partnering with you.
2. Purchase from a reputable, established manufacturer.
3. Equipment must integrate well with existing and future equipment.
4. Equipment must be supportable and well documented.
5. Equipment and system overall must be reliable.
6. Equipment must be easy to use and not cause disruptions to the every day business operation.
7. Equipment must be non-proprietary, proven technology.
EPG equipment uses the open architecture Modbus protocol, is well documented, and will integrate into any existing system. For over 20 years we have been manufacturing dependable, cost-effective process control solutions for thousands of industry professionals. If you have any questions or would like to talk to a Data Acquisition, SCADA or Telemetry hardware specialist, please give us a call at 800-443-7426. We look forward to partnering with you.
Protocol-Encoding/Decoding
1. Will the future system use existing protocol? (If new purchase, do not use proprietary protocol! You will reduce your options for integrating future equipment. If possible, use the Modbus protocol.)
2. Is there complete documentation?
3. What existing equipment do you need to connect to?
4. Do you need a multi-vendor software application to communicate with a variety of manufacturer's equipment?
5. Consider the security issues: What type of protection/safeguards will be needed and used to keep out hacking, tampering, sabotage and other unauthorized use.
(Master Control Station)
1. Do you need the master station to control local input/output and back up operations?
2. How many sites and stations does your application require?
3. Will the remote station collect data independent from the master station?
2. Is there complete documentation?
3. What existing equipment do you need to connect to?
4. Do you need a multi-vendor software application to communicate with a variety of manufacturer's equipment?
5. Consider the security issues: What type of protection/safeguards will be needed and used to keep out hacking, tampering, sabotage and other unauthorized use.
(Master Control Station)
1. Do you need the master station to control local input/output and back up operations?
2. How many sites and stations does your application require?
3. Will the remote station collect data independent from the master station?
Future System Needs
(Telemetry/Communication Path)
1. Where will the control center be located?
2. What is the distance you need to span between sites?
3. Will additional sites be added in the future?
4. What obstacles are between the control center and each present and future site, if known?
5. What topology and transmission mode is best suited for your application?
6. What transmission media is available? (May be different for each site.)
7. What are your maintenance/service needs? Will you assign your own maintenance personnel or contract out?
8. How much is in the budget to spend?
1. Where will the control center be located?
2. What is the distance you need to span between sites?
3. Will additional sites be added in the future?
4. What obstacles are between the control center and each present and future site, if known?
5. What topology and transmission mode is best suited for your application?
6. What transmission media is available? (May be different for each site.)
7. What are your maintenance/service needs? Will you assign your own maintenance personnel or contract out?
8. How much is in the budget to spend?
IN REVIEW
IN REVIEW
SCADA systems of today are an excellent means for operators of process control sites to save time and money. But from the hundreds of SCADA system providers to choose from, one poor decision may lead you down the path to countless frustrations, inefficiencies and unnecessary expenses. We at EPG Companies Inc. have prepared this pre-system assessment to help prepare the way for you to purchase a SCADA system that will give you years of cost-effective and dependable process control while leaving you open for tomorrows expansions and options. In closing consider the following:
QUESTIONS TO CONSIDER
The ROI (return on investment) and benefits produced by a properly engineered PLC SCADA system will far outweigh your initial investment if the right equipment is chosen and installed correctly. To help facilitate a suitable and beneficial choice, consider answering the following:
Existing Equipment
1. How many sites do you have in operation?
2. What type of equipment is presently in place at all sites? (pumps, valves, monitors, etc.)
3. What type of equipment will be installed in the future? (upgrades, additions, new sites, etc.)
4. What type of telemetry, data acquisition or SCADA system is presently installed? (proprietary, outdated, basic telemetry, etc.)
5. What type of telemetry network or communication path is presently in place?
Topology: Point-to-Point, Point-to-Multipoint, Multipoint-to-Multipoint
Transmission Mode: Hardwire, Telephone, Fiber Optics, Radio/Microwave
6. What type of protocol is being used and will it integrate well with future equipment?
7. What type of software is being used with the present system? Does it come with complete documentation and support? Is it likely to be supported in the future?
8. How many data-dependent users are on the present system?
9. How well would you rate the performance standards of your present system? Is it reliable?
10. What equipment can/will continue to be used? (field equipment, present SCADA components, software, etc.)
11. Can the present equipment and/or upgrades integrate well and communicate with the new equipment?
12. What type of maintenance or service arrangement is presently in place? How will it change with new equipment?
13. What are your present costs for inspection, maintenance and repair? How can it be changed to be cost-effective? How will it change with a new SCADA or data acquisition system?
14. If changes are made to the present system, will outside vendors (telephone company, satellite links, etc.) service change and what are those changes? (new transmission modes, service charges, etc.)
SCADA systems of today are an excellent means for operators of process control sites to save time and money. But from the hundreds of SCADA system providers to choose from, one poor decision may lead you down the path to countless frustrations, inefficiencies and unnecessary expenses. We at EPG Companies Inc. have prepared this pre-system assessment to help prepare the way for you to purchase a SCADA system that will give you years of cost-effective and dependable process control while leaving you open for tomorrows expansions and options. In closing consider the following:
QUESTIONS TO CONSIDER
The ROI (return on investment) and benefits produced by a properly engineered PLC SCADA system will far outweigh your initial investment if the right equipment is chosen and installed correctly. To help facilitate a suitable and beneficial choice, consider answering the following:
Existing Equipment
1. How many sites do you have in operation?
2. What type of equipment is presently in place at all sites? (pumps, valves, monitors, etc.)
3. What type of equipment will be installed in the future? (upgrades, additions, new sites, etc.)
4. What type of telemetry, data acquisition or SCADA system is presently installed? (proprietary, outdated, basic telemetry, etc.)
5. What type of telemetry network or communication path is presently in place?
Topology: Point-to-Point, Point-to-Multipoint, Multipoint-to-Multipoint
Transmission Mode: Hardwire, Telephone, Fiber Optics, Radio/Microwave
6. What type of protocol is being used and will it integrate well with future equipment?
7. What type of software is being used with the present system? Does it come with complete documentation and support? Is it likely to be supported in the future?
8. How many data-dependent users are on the present system?
9. How well would you rate the performance standards of your present system? Is it reliable?
10. What equipment can/will continue to be used? (field equipment, present SCADA components, software, etc.)
11. Can the present equipment and/or upgrades integrate well and communicate with the new equipment?
12. What type of maintenance or service arrangement is presently in place? How will it change with new equipment?
13. What are your present costs for inspection, maintenance and repair? How can it be changed to be cost-effective? How will it change with a new SCADA or data acquisition system?
14. If changes are made to the present system, will outside vendors (telephone company, satellite links, etc.) service change and what are those changes? (new transmission modes, service charges, etc.)
Benefits
Benefits:
* PLC-based equipment is usually more reliable and can run without direction from the master control.
* Operators can see real-time system trouble.
* The number of customer complaints/inquiries can be drastically reduced, for example: incoming calls concerning low pressure or poor water quality in water systems.
* PLC SCADA systems save time and money.
* Wear and tear on equipment can be reduced by continuously monitoring levels.
* The number of man-hours for troubleshooting and/or maintenance can be drastically reduced.
* Labor costs can be reduced through automatic report generating.
* Operating costs can be reduced and greater ROI (return on investment) can be achieved by using a PLC-based SCADA system compared to a proprietary system.
* Compliance with local, state & federal agencies is met easier.
* Expensive service calls by repair technicians can be eliminated.
* Local system integrators and electrical distributors can provide the needed support.
* NBT PLC-based SCADA systems use open architecture, non-proprietary products and protocol. Price lists are published to eliminate "hostage", discriminatory price fixing.
You may be able to think of some additional benefits that would be applicable to your own site. Begin by answering the following questions:
1. What could a PLC SCADA system do for your site?
2. What type of operation would it perform at the master/remote site?
3. What are some benefits you would like to receive by having a PLC SCADA system installed at your site?
4. What aspect of SCADA systems do you need more information on? Organize your thoughts for future reference and then give us a call if you need more help.
* PLC-based equipment is usually more reliable and can run without direction from the master control.
* Operators can see real-time system trouble.
* The number of customer complaints/inquiries can be drastically reduced, for example: incoming calls concerning low pressure or poor water quality in water systems.
* PLC SCADA systems save time and money.
* Wear and tear on equipment can be reduced by continuously monitoring levels.
* The number of man-hours for troubleshooting and/or maintenance can be drastically reduced.
* Labor costs can be reduced through automatic report generating.
* Operating costs can be reduced and greater ROI (return on investment) can be achieved by using a PLC-based SCADA system compared to a proprietary system.
* Compliance with local, state & federal agencies is met easier.
* Expensive service calls by repair technicians can be eliminated.
* Local system integrators and electrical distributors can provide the needed support.
* NBT PLC-based SCADA systems use open architecture, non-proprietary products and protocol. Price lists are published to eliminate "hostage", discriminatory price fixing.
You may be able to think of some additional benefits that would be applicable to your own site. Begin by answering the following questions:
1. What could a PLC SCADA system do for your site?
2. What type of operation would it perform at the master/remote site?
3. What are some benefits you would like to receive by having a PLC SCADA system installed at your site?
4. What aspect of SCADA systems do you need more information on? Organize your thoughts for future reference and then give us a call if you need more help.
FEATURES
FEATURES & BENEFITS
Now lets look at some of the features and benefits you'll receive from a properly engineered PLC-based SCADA system.
Features:
* PLCs have no moving parts. They are extremely robust and reliable.
* If communication with the MTU is lost, a PLC-based RTU can operate alone through "intelligent" programming.
* PLC programs are easy to understand and easy to use and can be completely documented with simple and extensive descriptions, technical programming and support manuals.
* PLCs are modular and can provide room for future expansion and growth.
* Programming for security sensors can be integrated into PLCs providing security and monitoring of door switches, heat and motion detectors. The SCADA system can then automatically notify as prescribed.
* No waiting period to replace electrical components. The SCADA system can be designed to use components that any local or national electrical distributor supplies.
* Standard built in diagnostics can continuously monitor and display all status and fault information in easy to understand text.
* The HMI (Human Machine Interface) software can provide extensive, on-screen documentation including operators manual, wiring diagrams, programs, etc.
* PLC-based SCADA systems can automatically gather and report data necessary to comply with local, state and federal regulations in formats that integrate well will Microsoft Excel, Access and Word.
* Data collected can be stored in the PLC and also in the MTU’s database providing a more robust reporting system.
* The SCADA system can keep managers and operators informed 24 hours a day through automatic email, paging and dial-up call features.
* Future upgrades and/or new installations of pumps, monitoring systems, level and flow sensors etc., can be easily integrated into the system.
* Multiple user features can easily be integrated into the SCADA system through web-based technology.
Now lets look at some of the features and benefits you'll receive from a properly engineered PLC-based SCADA system.
Features:
* PLCs have no moving parts. They are extremely robust and reliable.
* If communication with the MTU is lost, a PLC-based RTU can operate alone through "intelligent" programming.
* PLC programs are easy to understand and easy to use and can be completely documented with simple and extensive descriptions, technical programming and support manuals.
* PLCs are modular and can provide room for future expansion and growth.
* Programming for security sensors can be integrated into PLCs providing security and monitoring of door switches, heat and motion detectors. The SCADA system can then automatically notify as prescribed.
* No waiting period to replace electrical components. The SCADA system can be designed to use components that any local or national electrical distributor supplies.
* Standard built in diagnostics can continuously monitor and display all status and fault information in easy to understand text.
* The HMI (Human Machine Interface) software can provide extensive, on-screen documentation including operators manual, wiring diagrams, programs, etc.
* PLC-based SCADA systems can automatically gather and report data necessary to comply with local, state and federal regulations in formats that integrate well will Microsoft Excel, Access and Word.
* Data collected can be stored in the PLC and also in the MTU’s database providing a more robust reporting system.
* The SCADA system can keep managers and operators informed 24 hours a day through automatic email, paging and dial-up call features.
* Future upgrades and/or new installations of pumps, monitoring systems, level and flow sensors etc., can be easily integrated into the system.
* Multiple user features can easily be integrated into the SCADA system through web-based technology.
SCADA Software
A typical SCADA system provides a Human Machine Interface (HMI) allowing the operator to visualize all the functions as the system is operating. The operator can also use the HMI to change set points, view critical condition alerts and warnings, and analyze, archive or present data trends. Since the advent of Windows NT, the HMI software can be installed on PC hardware as a reliable representation of the real system at work.
Common HMI software packages include Cimplicity (GE-Fanuc), RSView (Rockwell Automation), IFIX (Intellution) and InTouch (Wonderware). Most of these software packages use standard data manipulation/presentation tools for reporting and archiving data and integrate well with Microsoft Excel, Access and Word.
Web-based technology is widely being accepted as well. Data collected by the SCADA system is sent to web servers that dynamically generate HTML pages. These pages are then sent to a LAN system at the operator’s site or published to the Internet.
THE MICROPROCESSOR OPTION
Now that you have a basic understanding of the SCADA system components, you may want to consider utilizing a microprocessor (MP) and/or a PLC-based SCADA system over a basic RTU or a proprietary system for the following reasons:
MPs, like MTUs, can continuously collect, process and store data, operating independently from the MTU through "intelligent" programming. In addition, by utilizing the EPG 2551 microprocessor-based level meter (pictured), you can have a robust SCADA system with both a master and a local display that automatically gathers, processes, and reports data necessary to comply with local, state and federal regulations in formats that integrate well will Microsoft Excel, Access and Word.
MPs can provide security and monitoring of door switches, heat and motion detectors. Managers/operators can be informed 24 hours a day through automatic email, paging and dial-up call features. Multiple users can easily be added and if open architecture protocol is used, future equipment can easily be integrated. Since MPs have no moving parts, they are extremely reliable and can be designed to be repairable with components that any local electrical distributor supplies.
MP-based SCADA system can reduce the number of man-hours needed for on-site visual inspections, adjustments, data collection and logging. Continually monitoring and troubleshooting potential problems increases equipment life, reduces service calls, reduces customer complaints and increases system efficiency. Simply put, open-architecture, MP-based SCADA systems are an excellent means for process control facilities to save time and money.
Common HMI software packages include Cimplicity (GE-Fanuc), RSView (Rockwell Automation), IFIX (Intellution) and InTouch (Wonderware). Most of these software packages use standard data manipulation/presentation tools for reporting and archiving data and integrate well with Microsoft Excel, Access and Word.
Web-based technology is widely being accepted as well. Data collected by the SCADA system is sent to web servers that dynamically generate HTML pages. These pages are then sent to a LAN system at the operator’s site or published to the Internet.
THE MICROPROCESSOR OPTION
Now that you have a basic understanding of the SCADA system components, you may want to consider utilizing a microprocessor (MP) and/or a PLC-based SCADA system over a basic RTU or a proprietary system for the following reasons:
MPs, like MTUs, can continuously collect, process and store data, operating independently from the MTU through "intelligent" programming. In addition, by utilizing the EPG 2551 microprocessor-based level meter (pictured), you can have a robust SCADA system with both a master and a local display that automatically gathers, processes, and reports data necessary to comply with local, state and federal regulations in formats that integrate well will Microsoft Excel, Access and Word.
MPs can provide security and monitoring of door switches, heat and motion detectors. Managers/operators can be informed 24 hours a day through automatic email, paging and dial-up call features. Multiple users can easily be added and if open architecture protocol is used, future equipment can easily be integrated. Since MPs have no moving parts, they are extremely reliable and can be designed to be repairable with components that any local electrical distributor supplies.
MP-based SCADA system can reduce the number of man-hours needed for on-site visual inspections, adjustments, data collection and logging. Continually monitoring and troubleshooting potential problems increases equipment life, reduces service calls, reduces customer complaints and increases system efficiency. Simply put, open-architecture, MP-based SCADA systems are an excellent means for process control facilities to save time and money.
Communication Equipment
The way the SCADA system network (topology) is set up can vary with each system but there must be uninterrupted, bidirectional communication between the MTU and the RTU for a SCADA or Data Acquisition system to function properly. This can be accomplished in various ways, i.e. private wire lines, buried cable, telephone, radios, modems, microwave dishes, satellites, or other atmospheric means, and many times, systems employ more than one means of communicating to the remote site. This may include dial-up or dedicated voice grade telephone lines, DSL (Digital Subscriber Line), Integrated Service Digital Network (ISDN), cable, fiber optics, WiFi, or other broadband services.
There are many options to consider when selecting the appropriate communication equipment and can include either a public and/or private medium. Public medium is a communication service that the customer pays for on a monthly or per time or volume use. Private mediums are owned, licensed, operated and serviced by the user. If you choose to use a private medium, consider the staffing requirements necessary to support the technical and maintenance aspects of the system.
Private Media Types:
Private Wire
Sometimes it makes sense to string or bury your own cable between sites to provide continuous communication. This type of media usually is limited to low bandwidth modems.
Wireless
(Spread Spectrum Radio)
This media type is license-free and available to the public in the 900 MHz and 5.8GHz bands. The higher the frequency used in the system, the more "line of sight" it becomes. Some Spread Spectrum radio units have the ability to span distances by re-strengthening signals for the next radio in line, acting like a repeater for other units in the network. Spread Spectrum radio modems generally have built in error correction, encryption and other features that make them a reliable, secure and long-lasting solution for network communication.
(Microwave Radio)
Microwave radio transmits at high frequencies through parabolic dishes mounted on towers or on top of buildings. This media uses point-to-point, line-of-sight technology and communications may become interrupted at times due to misalignment and/or atmospheric conditions.
(VHF/UHF Radio)
Good for up to 30 miles, VHF/UHF radio is an electromagnetic transmission with frequencies of 175MHz-450MGz-900MHz received by special antennas. A license from the FCC must be obtained and coverage is limited to special geographical boundaries.
Public Media Types:
(Telephone Company)
There are different services that your local telephone company can provide including: Switched Lines, Private Leased Lines, Digital Data Service, Cellular and PCS/CDPD.
* Switched Lines: Public Switch Telephone Network (PSTN) and Generally Switched Telephone network (GSTN) are dial-up voice and data transmission networks furnished by your local telephone company.
* Private Leased Lines: Private Leased Lines (PLL) are permanently connected 24 hours a day between two or more locations and used for analog (continuously varying signal) data transmission.
* Digital Data Service: Digital Data Service (DDS) is a private leased line with a special bandwidth used to transfer data at a higher speed and lower error rate. This service is applicable for computer-to-computer links.
* Cellular: This service is equivalent to Switched Line services over landlines.
* PCS/CDPD: This service is provided by cellular companies on a monthly fee or traffic volume basis and is used when continuous communication is needed.
Other Media Types:
(WiFi-SMR)
Sometimes it makes sense to use the infrastructure of another company. WiFi equipment utilizes broadband with high data rates and is used in a "time-share" basis to communicate between sites of the system. This media type generally requires advanced protocols like TCP/IP and network type connections.
(Satellite-Geosychronous/LEO)
Geosynchronous satellite's orbits are synchronous with the earth's orbit and remain in the same position with respect to the earth. These satellites use high frequency transmissions received by parabolic dish antennas. Low Earth Orbit (LEO) satellites hand off signals to other satellites for continuous coverage and latency times are less than geosynchronous satellites due to the lower orbit.
There are many options to consider when selecting the appropriate communication equipment and can include either a public and/or private medium. Public medium is a communication service that the customer pays for on a monthly or per time or volume use. Private mediums are owned, licensed, operated and serviced by the user. If you choose to use a private medium, consider the staffing requirements necessary to support the technical and maintenance aspects of the system.
Private Media Types:
Private Wire
Sometimes it makes sense to string or bury your own cable between sites to provide continuous communication. This type of media usually is limited to low bandwidth modems.
Wireless
(Spread Spectrum Radio)
This media type is license-free and available to the public in the 900 MHz and 5.8GHz bands. The higher the frequency used in the system, the more "line of sight" it becomes. Some Spread Spectrum radio units have the ability to span distances by re-strengthening signals for the next radio in line, acting like a repeater for other units in the network. Spread Spectrum radio modems generally have built in error correction, encryption and other features that make them a reliable, secure and long-lasting solution for network communication.
(Microwave Radio)
Microwave radio transmits at high frequencies through parabolic dishes mounted on towers or on top of buildings. This media uses point-to-point, line-of-sight technology and communications may become interrupted at times due to misalignment and/or atmospheric conditions.
(VHF/UHF Radio)
Good for up to 30 miles, VHF/UHF radio is an electromagnetic transmission with frequencies of 175MHz-450MGz-900MHz received by special antennas. A license from the FCC must be obtained and coverage is limited to special geographical boundaries.
Public Media Types:
(Telephone Company)
There are different services that your local telephone company can provide including: Switched Lines, Private Leased Lines, Digital Data Service, Cellular and PCS/CDPD.
* Switched Lines: Public Switch Telephone Network (PSTN) and Generally Switched Telephone network (GSTN) are dial-up voice and data transmission networks furnished by your local telephone company.
* Private Leased Lines: Private Leased Lines (PLL) are permanently connected 24 hours a day between two or more locations and used for analog (continuously varying signal) data transmission.
* Digital Data Service: Digital Data Service (DDS) is a private leased line with a special bandwidth used to transfer data at a higher speed and lower error rate. This service is applicable for computer-to-computer links.
* Cellular: This service is equivalent to Switched Line services over landlines.
* PCS/CDPD: This service is provided by cellular companies on a monthly fee or traffic volume basis and is used when continuous communication is needed.
Other Media Types:
(WiFi-SMR)
Sometimes it makes sense to use the infrastructure of another company. WiFi equipment utilizes broadband with high data rates and is used in a "time-share" basis to communicate between sites of the system. This media type generally requires advanced protocols like TCP/IP and network type connections.
(Satellite-Geosychronous/LEO)
Geosynchronous satellite's orbits are synchronous with the earth's orbit and remain in the same position with respect to the earth. These satellites use high frequency transmissions received by parabolic dish antennas. Low Earth Orbit (LEO) satellites hand off signals to other satellites for continuous coverage and latency times are less than geosynchronous satellites due to the lower orbit.
Remote Terminal Unit (RTU)
Remote Terminal Unit (RTU)
The Remote Terminal Unit is usually defined as a communication satellite within the SCADA system and is located at the remote site. The RTU gathers data from field devices (pumps, valves, alarms, etc.) in memory until the MTU initiates a send command. Some RTUs are designed with microcomputers and programmable logic controllers (PLCs) that can perform functions at the remote site without any direction from the MTU. In addition, PLCs can be modular and expandable for the purpose of monitoring and controlling additional field devices. Within the RTU is the central processing unit (CPU) that receives a data stream from the protocol that the communication equipment uses. The protocol can be open like Modbus, Transmission Control Protocol and Internet Protocol (TCP/IP) or a proprietary closed protocol. When the RTU sees its node address embedded in the protocol, data is interpreted and the CPU directs the specified action to take.
During the sixties, many manufacturers developed RTUs with communicative functions that performed a few specific tasks such as monitor and control digital and analog field devices. These all-in-one RTUs needed constant communication with the MTU in order to operate. A wide variety of programming languages were used that were not well known or supported. In the eighties the first micro PLCs were introduced as the first Open Architecture technology which has evolved and gained acceptance as todays preferred alternative to closed, proprietary systems.
Some manufacturers, like EPGs SCADA division NBT, now make Remote Access PLCs (RAPLC) specifically designed for SCADA and Data Acquisition applications. With NBTs PLC system, you can:
* Perform control
* Check site conditions
* Re-program anytime from anywhere
* Have any alarm or event trigger a call to your personal computer
This can all be done from a single, master site and the system can control one or multiple sites. Both industry representatives and customers welcome these smart PLCs because they provide remote programmable functionality while retaining the communications capability of an RTU.
The Remote Terminal Unit is usually defined as a communication satellite within the SCADA system and is located at the remote site. The RTU gathers data from field devices (pumps, valves, alarms, etc.) in memory until the MTU initiates a send command. Some RTUs are designed with microcomputers and programmable logic controllers (PLCs) that can perform functions at the remote site without any direction from the MTU. In addition, PLCs can be modular and expandable for the purpose of monitoring and controlling additional field devices. Within the RTU is the central processing unit (CPU) that receives a data stream from the protocol that the communication equipment uses. The protocol can be open like Modbus, Transmission Control Protocol and Internet Protocol (TCP/IP) or a proprietary closed protocol. When the RTU sees its node address embedded in the protocol, data is interpreted and the CPU directs the specified action to take.
During the sixties, many manufacturers developed RTUs with communicative functions that performed a few specific tasks such as monitor and control digital and analog field devices. These all-in-one RTUs needed constant communication with the MTU in order to operate. A wide variety of programming languages were used that were not well known or supported. In the eighties the first micro PLCs were introduced as the first Open Architecture technology which has evolved and gained acceptance as todays preferred alternative to closed, proprietary systems.
Some manufacturers, like EPGs SCADA division NBT, now make Remote Access PLCs (RAPLC) specifically designed for SCADA and Data Acquisition applications. With NBTs PLC system, you can:
* Perform control
* Check site conditions
* Re-program anytime from anywhere
* Have any alarm or event trigger a call to your personal computer
This can all be done from a single, master site and the system can control one or multiple sites. Both industry representatives and customers welcome these smart PLCs because they provide remote programmable functionality while retaining the communications capability of an RTU.
SYSTEM COMPONENTS -MTU
SCADA systems typically have four major elements:
1. Master Terminal Unit (MTU)
2. Remote Terminal Unit (RTU)
3. Communication Equipment
4. SCADA Software
1. Master Terminal Unit (MTU)
The Master Terminal Unit is usually defined as the master or heart of a SCADA system and is located at the operators central control facility. The MTU initiates virtually all communication with remote sites and interfaces with an operator. Data from remote field devices (pumps, valves, alarms, etc.) is sent to the MTU to be processed, stored and/or sent to other systems. For example, the MTU may send the data to the operators display console, store the information, and then send an operators initiate command to a field pumps RTU.
1. Master Terminal Unit (MTU)
2. Remote Terminal Unit (RTU)
3. Communication Equipment
4. SCADA Software
1. Master Terminal Unit (MTU)
The Master Terminal Unit is usually defined as the master or heart of a SCADA system and is located at the operators central control facility. The MTU initiates virtually all communication with remote sites and interfaces with an operator. Data from remote field devices (pumps, valves, alarms, etc.) is sent to the MTU to be processed, stored and/or sent to other systems. For example, the MTU may send the data to the operators display console, store the information, and then send an operators initiate command to a field pumps RTU.
A BRIEF HISTORY
The development of SCADA can be traced back to the early 1900s with the advent of telemetry. Telemetry involves the transmission and collection of data obtained by sensing real-time conditions. The monitoring of remote conditions became possible with the convergence of electricity, telegraph, telephone, and wireless communication technology. Throughout the last century, more industries, such as gas, electric, and water utilities, used telemetry systems to monitor processes at remote sites.
SCADA began in the early sixties as an electronic system operating as Input/Output (I/O) signal transmissions between a master station and a Remote Terminal Unit (RTU) station. The master station would receive the I/O transmissions from the RTU through a telemetry network and then store the data on mainframe computers.
In the early seventies, DCS (Distributed Control Systems) were developed. The ISAS5.1 standard defines a distributed control system as a system that while being functionally integrated consists of subsystems, which may be physically separate and remotely located from one another. Large manufacturers and process facilities utilized DCS primarily because they required large amounts of analog control.
Further development enabled Distributed Control Systems to use Programmable Logic Controllers (PLC), which being more intelligent than RTUs, have the ability to control sites without taking direction from a master.
In the late nineties, the differences between SCADA and DCS blurred. SCADA systems had DCS capabilities. DCS had SCADA capabilities. Systems were customized based on certain control features built in by designers. Now with the Internet being utilized more as a communication tool, control functions that were once old telemetry systems are becoming more advanced, interconnected and accessible. Automated software products are being developed to exploit the inter-connectivity of the Internet and certain portals can connect to a SCADA system and download information or control a process.
Good SCADA systems today not only control processes but are also used for measuring, forecasting, billing, analyzing and planning. Todays SCADA system must meet a whole new level of control automation, interfacing with yesterdays obsolete equipment yet flexible enough to adapt to tomorrows changes.
Whether you need a new system or are upgrading an older one, it is important to know the system components before you decide on who to talk with and what equipment you will need for your particular application.
SCADA began in the early sixties as an electronic system operating as Input/Output (I/O) signal transmissions between a master station and a Remote Terminal Unit (RTU) station. The master station would receive the I/O transmissions from the RTU through a telemetry network and then store the data on mainframe computers.
In the early seventies, DCS (Distributed Control Systems) were developed. The ISAS5.1 standard defines a distributed control system as a system that while being functionally integrated consists of subsystems, which may be physically separate and remotely located from one another. Large manufacturers and process facilities utilized DCS primarily because they required large amounts of analog control.
Further development enabled Distributed Control Systems to use Programmable Logic Controllers (PLC), which being more intelligent than RTUs, have the ability to control sites without taking direction from a master.
In the late nineties, the differences between SCADA and DCS blurred. SCADA systems had DCS capabilities. DCS had SCADA capabilities. Systems were customized based on certain control features built in by designers. Now with the Internet being utilized more as a communication tool, control functions that were once old telemetry systems are becoming more advanced, interconnected and accessible. Automated software products are being developed to exploit the inter-connectivity of the Internet and certain portals can connect to a SCADA system and download information or control a process.
Good SCADA systems today not only control processes but are also used for measuring, forecasting, billing, analyzing and planning. Todays SCADA system must meet a whole new level of control automation, interfacing with yesterdays obsolete equipment yet flexible enough to adapt to tomorrows changes.
Whether you need a new system or are upgrading an older one, it is important to know the system components before you decide on who to talk with and what equipment you will need for your particular application.
Marketing
Sales People and/or Flashy Marketing:
Good sales and marketing strategies are meant to produce top-of-mind, foot-in-the-door results. They may lure you or pressure you rather than equip you in making a sound decision based on all factors that affect optimum system performance.
These and other costly mistakes can be avoided through knowing, understanding, and carefully assessing your particular needs. For some, that may mean skimming through this article and then focusing on Table A and B below. For others, with little or no SCADA knowledge, you should read and become familiar with the background information provided below.
We at EPG Companies Inc. have prepared this Pre SCADA System Assessment to help equip you in determining what SCADA or Data Acquisition system is right for you. If you have any questions or comments after reviewing this assessment, please call us at 800-443-7426 and ask for a SCADA or Data Acquisition specialist. We have served the industry for over 20 years manufacturing systems that save time and money, are easy to use, and give years of dependable process control.
Good sales and marketing strategies are meant to produce top-of-mind, foot-in-the-door results. They may lure you or pressure you rather than equip you in making a sound decision based on all factors that affect optimum system performance.
These and other costly mistakes can be avoided through knowing, understanding, and carefully assessing your particular needs. For some, that may mean skimming through this article and then focusing on Table A and B below. For others, with little or no SCADA knowledge, you should read and become familiar with the background information provided below.
We at EPG Companies Inc. have prepared this Pre SCADA System Assessment to help equip you in determining what SCADA or Data Acquisition system is right for you. If you have any questions or comments after reviewing this assessment, please call us at 800-443-7426 and ask for a SCADA or Data Acquisition specialist. We have served the industry for over 20 years manufacturing systems that save time and money, are easy to use, and give years of dependable process control.
Experience
Years of Experience:
Be careful. There are a host of reputable SCADA providers with years of experience and knowledgeable expertise that have designed systems that are too broad, expensive and/or do not work. Many companies use this line as if it sets them apart from all the rest. Experience and knowledge is important but only as a starting point when determining what vendor is right for you.
Be careful. There are a host of reputable SCADA providers with years of experience and knowledgeable expertise that have designed systems that are too broad, expensive and/or do not work. Many companies use this line as if it sets them apart from all the rest. Experience and knowledge is important but only as a starting point when determining what vendor is right for you.
Customized Equipment
Excessively Complex or Customized Equipment:
Many operators are wowed by system specialists demonstrating all the capabilities of their SCADA system. After installation, the system is too complex for them to understand, operate and support. What you will have is a very expensive system running at minimum while the operator continues to work the old habits. The only recourse is to purchase expensive training and/or service contracts, which do not always guarantee prompt and professional service. Some SCADA systems have been shut down for months while waiting for a single source of technical support to arrive. Keep it simple wherever possible.
Many operators are wowed by system specialists demonstrating all the capabilities of their SCADA system. After installation, the system is too complex for them to understand, operate and support. What you will have is a very expensive system running at minimum while the operator continues to work the old habits. The only recourse is to purchase expensive training and/or service contracts, which do not always guarantee prompt and professional service. Some SCADA systems have been shut down for months while waiting for a single source of technical support to arrive. Keep it simple wherever possible.
Subscribe to:
Posts (Atom)