Question

How have communication systems changed over the past 35 years?

What is the most common form of communications systems found in modern SCADA systems? Why?

Answer 1

The communication has always been the crucial part of mankind's social life. The means of communication are changed according to the people's living conditions and all other such circumstances. Throughout history, the technology has had a huge impact on the means of communication. In the past, smoke was used as a means of communication from one mountain to another. Needless to say that only a few simple messages could be sent and received with this primitive method of smoke signals. Carrier pigeon was another means of communication to send messages further away. The pigeons were trained for this two way communication method of letter carrying. The letter, which was replaced with fax and e-mail consecutively, is used as a common means of communication as well. People need to send their messages further and faster as the world population has increased and started to be globalized. This period has been influenced by the methods of communication. Today, we use telephones, mobiles, text messages, e-mail, and internet chat programs as oral and literal ways of communication. The inventors and producers are aiming to develop faster, cheaper, smaller-sized, multi-tasking gadgets for communication. The communication technology has been changing to match our needs. However, the means of communication also shapes our life styles. Mobiles have been the most important things to carry after the identity card, the keys and the wallet.

Communications Network Options

The data can be transmitted through a variety of different communications platforms such as: Ethernet - A system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information Telephone Line - A system that utilizes electrical signals in order to transmit data over a distance using a single pair of copper (traditionally) wires. Optical Fiber Line- Similar to the traditional copper telephone lines, but differs by utilizing optical fibers made of glass or plastic and uses light to transmit the data, with is faster and has less losses as compared to copper wires. Radio/Wireless - A system that uses radio transmitters and receivers to send data over short distances. Typically requires line of sight for best application.

Cellular - Based on the cellular phone technology to transmit data, regardless of distance, but dependent on cellular signal coverage. Satellite - Similar to the cellular phone platform, but utilizing satellites instead of ground-based cellular towers. Wi-Fi - A technology increasing in popularity that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed internet connections. Earlier generation Wi-Fi systems can be notoriously insecure; Wireless Equivalent Privacy [WEP] is relatively easy to compromise, so care must be taken when selecting Wi-Fi equipment to ensure that it supports robust security. WPA2 is present in almost all currently available equipment, and its use should be mandated. Microwave – A system for providing long-range connectivity between two sites, utilizing either inexpensive public frequencies or FCC-licensed spectrum. Some microwave units are an extension of Wi-Fi – but for long range (20+ miles), others use proprietary protocols. To meet security and performance specifications, it is important to consider the endpoint of each connection. Point-to-point connections (such as Ethernet, Fiber, and Microwave) typically terminate at a central system management facility. Cellular systems may provide an Internet connection requiring additional security, and phone-line systems must be protected against security breaches through the standard land-line, twisted-pair copper wire network.

It is also important to consider the privacy offered by a solution; wireless solutions in particular need to pay attention to the possibility of a nearby device eavesdropping on an otherwise secure conversation. This can have profound implications if private data such as passwords are included in the gathered data. Finally, it is important to remember that these technologies are not mutually exclusive. A site can readily use a combination of Wi-Fi and Ethernet locally, and transmit the entirety of the site’s data to a central point through fiber, microwave or other longer-range technology. All of these communications methods fall under either hardwire or wireless category. Hardwire communication options include dedicated hardwire (i.e. Ethernet cable), fiber optic (i.e. light pipe), telephone wire (i.e. copper pair), or coaxial cable. Options for wireless data transmission include but are not limited to include satellite, radio, cellular, and Wi-Fi. Current industry trends suggest that wireless communication systems will continue to gain a larger market sector of the SCADA communication platforms, especially for large distributed networks such as water distribution systems where there is a need for a vast coverage area, perhaps in remote locations not readily accessible to existing hardwires. The same industry trends indicate that Ethernet is becoming the preferred communications standard for local area SCADAs, such as a water treatment plant.

If a system-wide SCADA, then consideration must be given to the size and terrain of the distribution system. For example, wireless may be a less expensive option, but the communications system would require adequate line of sight between the radio transmitters/receivers. Local availability of infrastructure and its proximity to the system feature that will require a SCADA sensor is also relevant. For example, if an there is an existing telephone line to a particular site where a sensor needs to be installed, then that telephone line may be the best option. Growth of the community could affect the SCADA system performance and future expandability as well as the ability to upgrade the system easily and budget for the system. Some of the more significant advantages and disadvantages are summarized in Table 1. Most modern SCADA systems use a variety of communication options within one system to meet their needs. Typically, there is not a one size fits all solution and SCADA communications should be tailor made to fit a utility’s needs.

If a system-wide SCADA, then consideration must be given to the size and terrain of the distribution system. For example, wireless may be a less expensive option, but the communications system would require adequate line of sight between the radio transmitters/receivers. Local availability of infrastructure and its proximity to the system feature that will require a SCADA sensor is also relevant. For example, if an there is an existing telephone line to a particular site where a sensor needs to be installed, then that telephone line may be the best option. Growth of the community could affect the SCADA system performance and future expandability as well as the ability to upgrade the system easily and budget for the system. Some of the more significant advantages and disadvantages are summarized in Table 1. Most modern SCADA systems use a variety of communication options within one system to meet their needs. Typically, there is not a one size fits all solution and SCADA communications should be tailor made to fit a utility’s needs.

Security should be considered on three levels:

· Perimeter Security, limiting access to systems and network equipment from

unauthorized sources.

· Interior Security, requiring at the very least a login to access important infrastructure.

· Transport Security, ensuring that it is difficult to illicitly access a network segment in

an attempt to gain control.

Additionally, a cohesive security plan requires the following components:

· Authentication, answering the question “who are you?” This is typically handled with a

login requirement (user’s name and password), although more secure systems are

possible. Ideally, a system should be compatible with a centralized login security system,

preventing the need to visit each device in order to revoke authorization whenever

personnel changes.

Authorization, answering the question “what are you allowed to do?” This dove-tails

with authentication. Again, an ideal system will centralize this authority permitting rapid

revocation of authorization in the event of personnel changes or a security breach.

· Accounting, answering the question “who did what?” In essence, this is an audit-trail,

allowing you to see which user performed what operation, and when they did it. This can

be an essential element of understanding an incident after it occurs, or catching it as it

begins.