1 What Does Scada Mean
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1 WHAT DOES SCADA MEAN? SCADA stands for Supervisory Control And Data Acquisition. The term SCADA usually refers to centralized systems which monitors and controls entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country). As such, it is a purely software package that is positioned on top of hardware to which it is interfaced, in general via Programmable Logic Controllers (PLCs), or other commercial hardware modules. 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 e.g., manufacturing, production, power generation, fabrication, and refining, and may run in continuous, batch, repetitive, or discrete modes. Infrastructure processes e.g., include water treatment and distribution, wastewater collection and treatment, oil and gas pipelines, electrical power transmission and distribution, Wind Farms, civil defence siren systems, and large communication systems. Facility processes e.g., buildings, airports, ships, and space stations. They monitor and control HVAC, access, and energy consumption.
How SCADA Systems Work A SCADA system performs four functions: 1. Data acquisition 2. Networked data communication 3. Data presentation 4. Control These functions are performed by these SCADA components: 1.Remote Terminal Units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays. Programmable Logic Controller (PLCs) used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs. 2. A Human-Machine Interface or HMI (Data Presentation) is the apparatus which presents process data to a human operator, and through this, the human operator monitors and controls the process. The term SCADA usually refers to centralized systems which monitors and controls entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country). 3. SCADA master units. These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs. A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to the process. 4. The communications network that connects the SCADA master unit to the RTUs in the field. Early SCADA networks communicated over radio, modem or dedicated serial lines. Today the trend is to put SCADA data on Ethernet.
SCADA architectures SCADA systems have evolved through 3 generations as follows: 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.
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.
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.
What to Look for in a SCADA RTU Your SCADA RTUs need to communicate with all your on-site equipment and survive under the harsh conditions of an industrial environment. Here’s a checklist of things you should expect from a quality RTU: 0 Sufficient capacity to support the equipment at your site … but not more capacity than you actually will use. At every site, you want an RTU that can support your expected growth over a reasonable period of time, but it’s simply wasteful to spend your budget on excess capacity that you won’t use. 0 Rugged construction and ability to withstand extremes of temperature and humidity. 0 Secure, redundant power supply. You need your SCADA system up and working 24/7, no excuses. Your RTU should support battery power and, ideally, two power inputs. 0 Redundant communication ports. Network connectivity is as important to SCADA operations as a power supply. A secondary serial port or internal modem will keep your RTU online even if the LAN fails. Plus, RTUs with multiple communication ports easily support a LAN migration strategy. 0 Nonvolatile memory (NVRAM) for storing software and/or firmware. NVRAM retains data even when power is lost. New firmware can be easily downloaded to NVRAM storage, often over LAN — so you can keep your RTUs’ capabilities up to date without excessive site visits. 0 Intelligent control. As I noted above, sophisticated SCADA remotes can control local systems by themselves according to programmed responses to sensor inputs. This isn’t necessary for every application, but it does come in handy for some users. 0 Real-time clock for accurate date/time stamping of reports. 0 Watchdog timer to ensure that the RTU restarts after a power failure. What to Look for in a SCADA Master Your SCADA master should display information in the most useful ways to human operators and intelligently regulated your managed systems. Here’s a checklist of SCADA master must-haves: 0 Flexible, programmable response to sensor inputs. Look for a system that provides easy tools for programming soft alarms (reports of complex events that
track combinations of sensor inputs and date/time statements) and soft controls (programmed control responses to sensor inputs).
0 24/7, automatic pager and email notification. There’s no need to pay personnel to watch a board 24 hours a day. If equipment needs human attention, the SCADA master can automatically page or email directly to repair technicians. 0 Detailed information display. You want a system that displays reports in plain English, with a complete description of what activity is happening and how you can manage it. 0 Nuisance alarm filtering. Nuisance alarms desensitize your staff to alarm reports, and they start to believe that all alarms are nonessential alarms. Eventually they stop responding even to critical alarms. Look for a SCADA master that includes tools to filter out nuisance alarms. 0 Expansion capability. A SCADA system is a long-term investment that will last for as long as 10 to 15 years. So you need to make sure it will support your future growth for up to 15 years. 0 Redundant, geodiverse backup. The best SCADA systems support multiple backup masters, in separate locations.. If the primary SCADA master fails, a second master on the network automatically takes over, with no interruption of monitoring and control functions. 0 Support for multiple protocols and equipment types. Early SCADA systems were built on closed, proprietary protocols. Single-vendor solutions aren’t a great idea — vendors sometimes drop support for their products or even just go out of business. Support for multiple open protocols safeguards your SCADA system against unplanned obsolescence.
How SCADA Systems Work A SCADA system performs four functions: 1. Data acquisition 2. Networked data communication 3. Data presentation 4. Control These functions are performed by these SCADA components: 1.Remote Terminal Units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays. Programmable Logic Controller (PLCs) used as field devices because they are more economical, versatile, flexible, and configurable than special-purpose RTUs. 2. A Human-Machine Interface or HMI (Data Presentation) is the apparatus which presents process data to a human operator, and through this, the human operator monitors and controls the process. The term SCADA usually refers to centralized systems which monitors and controls entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country). 3. SCADA master units. These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs. A supervisory (computer) system, gathering (acquiring) data on the process and sending commands (control) to the process. 4. The communications network that connects the SCADA master unit to the RTUs in the field. Early SCADA networks communicated over radio, modem or dedicated serial lines. Today the trend is to put SCADA data on Ethernet.
SCADA architectures SCADA systems have evolved through 3 generations as follows: 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.
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.
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.
What to Look for in a SCADA RTU Your SCADA RTUs need to communicate with all your on-site equipment and survive under the harsh conditions of an industrial environment. Here’s a checklist of things you should expect from a quality RTU: 0 Sufficient capacity to support the equipment at your site … but not more capacity than you actually will use. At every site, you want an RTU that can support your expected growth over a reasonable period of time, but it’s simply wasteful to spend your budget on excess capacity that you won’t use. 0 Rugged construction and ability to withstand extremes of temperature and humidity. 0 Secure, redundant power supply. You need your SCADA system up and working 24/7, no excuses. Your RTU should support battery power and, ideally, two power inputs. 0 Redundant communication ports. Network connectivity is as important to SCADA operations as a power supply. A secondary serial port or internal modem will keep your RTU online even if the LAN fails. Plus, RTUs with multiple communication ports easily support a LAN migration strategy. 0 Nonvolatile memory (NVRAM) for storing software and/or firmware. NVRAM retains data even when power is lost. New firmware can be easily downloaded to NVRAM storage, often over LAN — so you can keep your RTUs’ capabilities up to date without excessive site visits. 0 Intelligent control. As I noted above, sophisticated SCADA remotes can control local systems by themselves according to programmed responses to sensor inputs. This isn’t necessary for every application, but it does come in handy for some users. 0 Real-time clock for accurate date/time stamping of reports. 0 Watchdog timer to ensure that the RTU restarts after a power failure. What to Look for in a SCADA Master Your SCADA master should display information in the most useful ways to human operators and intelligently regulated your managed systems. Here’s a checklist of SCADA master must-haves: 0 Flexible, programmable response to sensor inputs. Look for a system that provides easy tools for programming soft alarms (reports of complex events that
track combinations of sensor inputs and date/time statements) and soft controls (programmed control responses to sensor inputs).
0 24/7, automatic pager and email notification. There’s no need to pay personnel to watch a board 24 hours a day. If equipment needs human attention, the SCADA master can automatically page or email directly to repair technicians. 0 Detailed information display. You want a system that displays reports in plain English, with a complete description of what activity is happening and how you can manage it. 0 Nuisance alarm filtering. Nuisance alarms desensitize your staff to alarm reports, and they start to believe that all alarms are nonessential alarms. Eventually they stop responding even to critical alarms. Look for a SCADA master that includes tools to filter out nuisance alarms. 0 Expansion capability. A SCADA system is a long-term investment that will last for as long as 10 to 15 years. So you need to make sure it will support your future growth for up to 15 years. 0 Redundant, geodiverse backup. The best SCADA systems support multiple backup masters, in separate locations.. If the primary SCADA master fails, a second master on the network automatically takes over, with no interruption of monitoring and control functions. 0 Support for multiple protocols and equipment types. Early SCADA systems were built on closed, proprietary protocols. Single-vendor solutions aren’t a great idea — vendors sometimes drop support for their products or even just go out of business. Support for multiple open protocols safeguards your SCADA system against unplanned obsolescence.
