⚙️Key Components

Servers

Used to store configuration for the ICS and saves process data in historians for later retrieval. The servers connect to business networks to allow remote operations, configuration, or information exchanges to improve productivity.

Human-Machine Interface (HMI)

The user interface in a manufacturing or process control system. It provides a graphics-based visualisation of an industrial control and monitoring system. Previously called an "MMI" (man-machine interface), an HMI typically resides on a computer that communicates with a specialized computer in the plant, such as a programmable automation controller (PAC), programmable logic controller (PLC) or remote terminal unit (RTU). The HMI generally comes in two forms: either a touch panel or a software-based application that is loaded on a personal computer, workstation, tablet, or smart phone.

The HMI provides the primary device that plant operators used to interact with and control the processes.

Examples of HMIs

• Workstations

• SCADA Server

• Emergency Management System

Engineering Workstations

A specialized type of HMI, typically interface with the servers to modify the database or controllers to ensure the critical process runs properly. As we gain an understanding of the similarities between IT and ICS architectures, we will have greater success mapping traditional cyber security issues into the ICS domain.

Field Controllers

The devices that consolidate inputs and outputs, taking the instructions from the operators to make changes in the field. Controllers can be programmed or updated in the field (remotely). These devices were designed as if they were in a “trusted” (the network map should show information about the trusted vs. un-trusted environments) environment. Therefore, when given a command, they obey or respond. Most do not authenticate to make sure they are receiving commands from a specific source.

Examples of Field Controllers:

• PLCs

• PAC

• RTU

• IED

Remote Terminal Unit (RTUs)

A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system or SCADA (supervisory control and data acquisition) system by transmitting telemetry data to a master system, and by using messages from the master supervisory system to control connected objects. As this interfacing involves the collection of telemetry data, the system is sometimes called a remote telemetry unit. One of the key characteristics of an RTU is that it relays information from a remote location over long distances to a centrally located host using/supporting a variety of communications mediums and ICS protocols.

RTU are capable of executing programs autonomously without having to involve the HMI or operator. This enables RTU to respond quickly to emergencies without operator input. For example, if the RTU program "sees" a high flow rate on one of the input flows, it can issue an output command to shut down a pump. In addition to converting analog or discrete measurements to digital information, RTU are also used as data concentrators and protocol converters. Typically, RTU are used by utilities and other industries that monitor and control geographically dispersed facilities.

Sectors Using RTUs

• Oil and gas – RTUs are used in offshore platforms, onshore oil wells, pipelines

• Refineries and chemical plants – RTUs are used in environmental monitoring systems (pollution, air quality, emissions monitoring), outdoor warning sirens

• Water and Wastewater – RTUs can be found in distribution systems, aqueducts, water resource management, collection systems

• Electric power – RTUs are used in transmission and distribution systems across the country

• Mine sites – RTUs are used in conveyor monitoring and control, mine water management, underground equipment monitoring, bore management, and material handling

• Transportation Systems – RTUs are used in air traffic control, railroads, and trucking

Intelligent Electronic Device (IED)

An Intelligent Electronic Device (IED) is a term used in the electric power industry to describe microprocessor-based controllers of power system equipment. It is used by the Energy sector to monitor and control electrical power devices such as circuit breakers, capacitors, and transformers. IED receive data from field sensors (I/O) and power equipment and can issue control commands. These commands include simple things such as tripping circuit breakers if they sense anomalies in voltage or current. They can also instruct system output to raise or lower voltage levels in order to maintain the desired level. Common types of IED include protective relaying devices, load tap changer controllers, circuit breaker controllers, capacitor bank switches, re-closer controllers, and voltage regulators.

Many owners/operators leave their IED with their “fresh out of the box” configurations. These default configurations, unfortunately, make it easier for those with ill intent to make changes to the operational parameters of the device. Furthermore, some owners opt to keep the extra communication programming ports active so they can view or make online changes from the shop or control room. Considering that modern IED are fully network aware, and in some cases, may have embedded services that facilitate remote administration, there is a valid concern for the cyber security of these devices.

The utilities which operated the power transmission stations were some of the first to use IED. This early use was not to comply with regulatory requirements, but to save money. The use of IED in this instance meant a highly paid technician would not have to drive to a potentially remote transmission station to retrieve data.

Programmable Logic Controllers

Programmable Logic Controllers (PLCs)

Programmable Automation Controller (PAC)

PAC is a term that is loosely used to describe any type of automation controller that incorporates higher-level instructions. The systems are used in ICS for machinery in a wide range of industries, including those involved in critical infrastructure. They provide a highly reliable, high-performance control platform for discrete logic control, motion control, and process control. There is no specific agreement between industry experts as to what differentiates a PAC from a PLC. In any case, defining exactly what constitutes a PAC is not as important as having users understand the types of applications for which each is best suited.

A PAC is geared more toward complex automation system architectures composed of a number of PC-based software applications, including HMI functions, asset management, historian, advanced process control (APC), and others. A PAC is also generally a better fit for applications with extensive process control requirements, as PACs are better able to handle analog I/O and related control functions. A PAC tends to provide greater flexibility in programming, larger memory capacity, better interoperability, and more features and functions in general.

PAC provide a more open architecture and modular design to facilitate communication and interoperability with other devices, networks, and enterprise systems. They can be easily used for communicating, monitoring, and control across various networks and devices because they employ standard protocols and network technologies, such as Ethernet, Open Platform Communication (OPC), and Structured Query Language (SQL.)

PACs also offer a single platform that operates in multiple domains, such as motion control, communication, sequential control and process control. Moreover, the modular design of a PAC simplifies system expansion and makes adding and removing sensors and other devices easy, often eliminating the need to disconnect wiring. Their modular design makes it easy to add and effectively monitor and control thousands of I/O points, a task beyond the reach of most PLC.

Field Devices

The instruments and sensors that measure process parameters and the actuators that control the process. This is the interface between the ICS and the physical process, be it the mixing of chemicals, the management of trains, or measuring of pressures in a gas pipeline.

This is the point in the system where information is collected about the process, modifications are made, and the process is controlled. The sensors or measuring instruments are often referred to as input devices because they "input" data into the ICS. In contrast, switches, valves, and other types of actuators that control the process are called output devices. This input and output information is often referred to as I/O.

Examples of Field Devices

• Meters

• Sensors

• Valves

• Switches

Field Device Inputs

Signals generated by discrete and analog field devices are converted to digital format in a networked environment. The digital signals extend the network to the instrument, and consequently, the process.

Sensors, or transmitters, collect data, or input, and are built into control instruments. The sensor may monitor one input point or measure over 100,000 points, such as within large refineries or utility front-end processors. The sensors convert physical parameters, such as temperature, pressure, level, flow, motor speed, valve state, or breaker position to electrical signals. The input device allows the operator to communicate and transmit instructions and data to computers for transmission, processing, display, or storage.

Signals generated by discrete and analog field devices are converted to digital format in a networked environment. The digital signals extend the network to the instrument, and consequently, the process.

Sensors are commonly described by their type: discrete, analog, and digital.

Discrete Sensors

Discrete input sensors support binary events including alarms and states. For example, the tank is full, the door is closed, the pressure is too high, or the pump is turned on.

Analog Sensors

Analog input sensors (transmitters) measure continuous processes such as flow, level, or pressures within a range; 0-100%, empty to full, 0 to 100 mph. Typically, they transmit this information to field controllers using an analog signal such as a 4 to 20-mA.

Digital Sensors

Digital input sensors are similar to both discrete and analog instruments in that they measure continuous processes (such as flows) and support binary events. However, instead of using an analog loop signal or clean contacts, digital sensors use a digitally encoded ICS communications protocol format (representing an equivalent to 1s and 0s) signal to relay the data.

Field Device Outputs

Discrete Outputs

Like their input counterpart, discrete output devices are also binary appliances. For instance, the field controller issues a signal to an output device, such as a circuit breaker, to open or close a breaker. Discrete output devices can communicate directly with discrete input devices. Furthermore, they can make control decisions and are programmable like a field controller.

Analog Outputs

The analog output transmits analog signals (voltage or current) that operate controls. Analog outputs are predominantly used to control actuators, valves, and motors in industrial environments. In this case, the field controller will send a varying electrical signal that can open or close the valve as needed.

Digital Outputs

A digital output allows you to control a voltage with a computer. If the computer instructs the output to be high, the output will produce a voltage (generally about 5 or 3.3 volts). If the computer instructs the output to be low, it is connected to ground and produces no voltage. As a result, they can communicate more quickly and reliably, thus enabling their use in environments that are more critical, covering a wider range of applications. Examples include: alarms, control relays, fans, lights, horns, valves, switches, motor starters, etc.

Safety Systems

Safety systems provide protection to the process, physical equipment, or people from harmful situations that may arise during operations. It is a counter action critical in industrial operations in the case of a process goes beyond allowable control parameters.

While this would result in a loss of productivity, it would spare the equipment and people harm. Safety systems are traditionally, designed to be separated from the control systems they protect. However, they frequently share some communications, field devices, alarms, etc.