Definitions

Term	Definition
ICS	Industrial Control Systems
HMI	Human Machine Interfaces provide a means for tool/machine operators to interact with their tools via a capacitive touch or push button display
IED	Providing an interconnect between two or more networks
DCS	Distributed Control Systems control production systems found in one location. A DCS is also commonly used in manufacturing, electric power generation, chemical manufacturing, oil refineries, and water and wastewater treatment
PLC	Programmable Logic Controllers, is a type of hardware used in both DCS and SCADA systems as a control component of an overall system
OT	Operational Technology variables include the hardware and software systems that monitor and control physical devices in the field. Devices that monitor the temperature in industrial environments are examples of OT devices
Control Server	Hosts the DCS or PLC supervisory control software and communicates with lower-level control devices
IED	Intelligent Electronic Devices are smart devices capable of acquiring data, communicating with other devices, and performing local processing and control
EGP	Exterior Gateway Protocol, a type of routing protocol used outside of a network for internetwork, not to be confused with the deprecated protocol by the same name
BGP	Border Gateway Protocol, a routing protocol used for large-scale, internetworking applications
RIP	Routing Information Protocol, a distance-vector routing protocol
OSPF	Open Shortest Path First, a link-state routing protocol
AS	Autonomous System, a value used by BGP to group routes

Communication Protocols

Devices and control modules in ICS systems relay information through communication protocols. There are several communication protocols used through various ICS environments. Most protocols are designed for specific purposes, such as process automation, building automation, power systems automation, and many more. The ICS protocols that are commonly found include:

Terms	Definitions
Process Field Bus (PROFIBUS)	PROFIBUS uses RTU to MTU, MTU to MTU, and RTU to RTU communications. There are two available variants: Profibus DP (decentralized peripherals), which is used to operate sensors and actuators through a central controller, and Profibus PA (process automation), which is used to monitor measuring equipment through a process control system
Distributed Network Protocol (DNP3)	This protocol has three layers operating at the data link, application, and transport layers. This protocol is widely used in electricity and water and wastewater treatment plants.
Modbus	There are two types of Modbus implementations: Serial Modbus – which uses the high-level data link control (HDLC) standard for data transmission, and Modbus-TCP – which uses the TCP/IP protocol stack to transmit data.
Open Platform Communication (OPC)	The OPC specification is based on technologies developed by Microsoft its operating system (OLE, COM, and DCOM)
Building Automation and Control Networks (BACnet)	This is a communication protocol that is designed to control heating, ventilating, and air-conditioning control (HVAC); lighting; building access; and fire detection
Common Industrial Protocol (CIP)	CIP is a set of services and messages for control, security, synchronization, configuration, information, and so forth. The ICP can be integrated into Ethernet networks and the internet. CIP has several adaptations providing intercommunication and integration for different types of networks
Ethernet for Control Automation Technology (EtherCAT)	An open-source communications protocol used to incorporate Ethernet into industrial environments. EtherCAT is used in automation applications with short updating cycles (≤ 100μs) and jitter ≤ 1μs.