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STANDARDS / GLOSSARIES / CONTROL SYSTEMS GLOSSARY
 
ADC Analogue to Digital Convertor
AI Artificial Intelligence
Algorithms Algorithms are routines to deal with particular situations; for example, a controller formula to correct an element in a continuous process.
Analogue Analogue devices are those which communicate via a small electric current. For example, food industry flow meters send a current of between 4mA to 20mA. The lowest value would represent no flow at all; the largest would indicate maximum flow.
ANN An abbreviation sometimes used for artificial neural networks.
ANSI American National Standards Institute.
APC Advanced Process Control. This includes continuous applications such as cracking towers and advanced batch control involving activities like blend ratio control or bleaching.
BMS Building Management System
CAD Computer Aided Design. This may allow designers to manipulate parts drawings and simulate processes.
CAM Computer Aided Manufacturing is a generic term for systems help manufacturing. They include CNC and process control.
CIM Computer Integrated Manufacturing is a term used to describe an operation which makes all or most of its information available through a fully integrated data management network. The object is to increase efficiency by integrating all the facility's data management systems.
Closed Systems See open systems. Closed systems are the opposite to open systems. In other words, they are proprietary.
CNC Computer Numerical Control allows machines to be operated from PLCs by means of a numerical code.
Console A console is the term for the actual screen and keyboard used in the work stations.
Controller A device which controls another machine in the process directly, usually being wired to it directly.
DAC Digital to Analogue Convertor
DCS A Distributed Control System is designed to have a series of decentralised control centres which have some degree of autonomy, but are still integrated into a whole system (except in an emergency shutdown). The centre has hierarchical control over the rest, but most control takes place away from the centre.
DDE Direct Digital Embedding.
Digital Digital devices transmit in bits, i.e. a series of binary numbers, to other parts of the system.
Discrete Process A process handling distinct, separate products. The usual example is an automotive factory product line, where each car is a distinct artefact. Discrete processes are in contradistinction to continuous processes handling liquids.
ERP Enterprise Resource Planning.
ESD Emergency Shut Down.
EWS Engineering Work Station
Expert Systems See Knowledge Based Systems (KBS).
Fault Tolerant Fault tolerant architecture allows the system to continue working even when part of the system fails. This is usually done by having multiple components running in parallel; when one part fails the redundant devices can take over, allowing engineers to repair the system without disrupting the process.
FCU Field Control Unit.
FDDI A Fibre Distributed Data Interface is a type of LAN.
FF Fieldbus Foundation.
Fieldbus Fieldbus is a generic term used to describe a common communications protocol for control systems and/or field instruments. Although some standard forms have been agreed for instruments, the DCS industry as a whole have so far no agreed fieldbus. Often, the Foundation Fieldbus is referred to simply as the Fieldbus.
Function Block Smart devices on a fieldbus are capable of operating independently. The microprocessors which store control software are the function blocks. They are particular to an application.
Fuzzy Logic Fuzzy logic is designed for situations where information is inexact and traditional digital on/off decisions are not possible. It divides data into vague categories such as "hot", "medium" and "cold".
Gas Chromatagraphs Gas chromatagraphs are used to analyse the make up of a gas at various points in the process. It has been suggested that neural networks might be used to replace their functions in some circumstances at much lower cost.
Genetic Algorithms (Gas) These are routines which are capable of self adaption. As with neural networks, they are based on an analogy with nature; in this case the best algorithms breed with each other to provide new variants in a "survival of the fittest". As yet this cutting edge technology is not widely used in process control.
GOT Graphic Operator Terminal. A kind of HMI.
Granule An information granule is a term used by some fuzzy logic experts to describe a fuzzy set of objects which can be seen as a unit in fuzzy logic calculations.
GUI The standard abbreviation for Graphic User Interface; this is an interface which uses graphics rather than characters to communicate.
GUS Global User Station
HMI Human Machine Interface. Sometimes these are called Man Machine Interface. See MMI.
HVAC Heating, Ventilation and Air Conditioning.
ICS An Information and Command Station is used by operators to control and monitor the plant's processes.
IEC International Electrotechnical Commission.
IFC International Fieldbus Consortium. An hybrid body formed from the IFG and the OFC in 1990. It voted to stop work after the FF was created in 1994.
IFG International Fieldbus Group
ILD Instrument Loop Diagram. A drawing showing the connections from the field device all the way through to the system terminations.
IMC Institute of Measurement and Control. InstMC.
Interchangability Interchangability is the ability, in an open system, to swap instruments on a network without losing functionality.
Interoperability Interoperability is the ability to plug instruments or other elements produced by more than one manufacturer into a fieldbus network and still have them able to communicate with each other and the control system(s). They may, however, have different levels of functionality.
I/O Module An Input/Output module, which usually contains several I/O points.
I/O point An Input/Output point, used as a connection point.
ISA Instrument Society of America.
ISP This is the standard abbreviation for the Interoperable Systems Project, which a number of companies are hoping will produce an international fieldbus. The main industry backers are Fisher-Rosemount, Yokogawa and Siemens.
JIT Just In Time. A manufacturing process that produces products just in time to meet orders, not for stock.
KBS A Knowledge Based System is a system which attempts to use a database to solve problems by inference. These are sometimes called expert systems.
LAN Local Area Networks are used to link up computers. The best known protocol for LANs is Ethernet.
LonWorks Local Operating Networks is another fieldbus, used by about 2,000 companies. The chips are made by Toshiba and Motorola for the German Echelon. They are then sold onto to various manufacturers.
Loop Each DCS controls a number of loops. These consist of a measurement device, a controller and a valve. Each loop is composed of devices to control the flow of liquid at a particular point.
Master Modules The master is set over the "slave" module, i.e. is able to control it. These are sometimes called "parent" modules.
MCS Management Command System. A kind of HMI.
MES Management Execution System. By monitoring labour resources, process history and machine usage & failures, a MES will help various features such as preventive maintenance, employee time & attendance, quantity maintenance and operator data.
MIS Management Information System
MMI Man-Machine Interface. Also known as Human Machine Interface (HMI).
Migration When manufacturers produce new products they usually provide a migration path whereby their existing clients can upgrade their systems without total replacement. Rival manufacturers also provide migration paths away from the systems of others' in order to gain market share.
MRPII Manufacturing Resource Planning 2.
Multitasking The ability of a computer to handle more than two programmes at the same time.
MTU Master Telemetry Unit
NC Numerical Controller
Neural Network A neural network is a computer network designed to function in a similar way to natural neural structures such as a human brain.
OCS Open Control System. This term is sometimes used to emphasise the lack of proprietary architecture. ABB include the term in their DCS brandname, Advant OCS.
OEM Original Equipment Manufacturer.
OFC Open Fieldbus Consortium.
OIS Operator Interface Station. A kind of HMI.
OLE Object Linking and Embedding, Microsoft's greatest contribution to industrial control, allows operators to link the same object in several different applications.
OPC OLE for process control.
Open Systems Open systems are customarily defined as those systems that can be supplied by hardware components from multiple vendors, and whose software can be operated from different platforms. They are opposite to closed or proprietary systems.
OS An OS is an abbreviation for an Operating System which is the basic computer system which makes all computers function.
PC Personal Computer
PFD Process Flow Diagram
PID PID stands for proportional, integral, derivative. Proportional means changing a variable in proportion to its difference from the set-point. Integral rectifies any small difference in the variable and the set-point. Derivative reduces the other oscillations.
P & ID Process and Instrumentation Diagram
PIMS Process Information Management System
PLC A Programmable Logic Controller is a controller which stores instructions to command a device, such as a valve, to which it is connected to start up, operate and shut down.
PNET The Danish fieldbus. The Profibus organisation is seeking to integrate this in the common Profibus PA protocol.
Process Variable An aspect of the processed product which changes during processing, e.g. temperature. Some variables can be measured, but in some processes some variables can only be judged by dead reckoning.
Profibus The German fieldbus, not to be confused with the common European fieldbus Profibus PA.
Profibus PA This is the name agreed on a common European Fieldbus for process automation, still disputed by mainly American companies. Its main pusher in the industry is Siemens.
Protocol A set of rules to govern system-to-system use. For example, a protocol might specify communication method, transmission rate, data format or error check method.
Redundancy This is the capacity to switch from primary equipment to standby equipment automatically without affecting the process under control.
RIO Bus Remote Input/Output bus. This is a communication bus used to connect a field control unit with remote I/O points or nodes.
RTU Remote Terminal Unit
Safety PLC A PLC specifically designed to be reliable through the device of redundancy. It could be used either for safety reasons or to minimise the commercial impact of a serious failure.
SCADA Supervisory Control And Data Acquisition software.
Set-point A desired level for a process variable. The systems seeks to correct the variable when it deviates from this standard.
SFC Sequence Function Chart. An IEC1131-1 programming/configuration language.
Single Window Single window refers to the ability to provide multiple displays via a single terminal.
Slave Modules Slave modules are distributed modules that report back to a central master. Despite the name, they have their own processing ability. Another name for them is "child" modules.
SLC Soft Logic Control.
Smart Device A device with intelligence, i.e. capable of monitoring itself.
Soft Logic A PC operating system used for soft control. It allows a PC to replace a PLC.
SPC Statistical Process Control.
Structured Text An IEC1131-1 programming/configuration language.
Tag This is a number given to individual DCS control units so that the system can identify them.
TMR In safety PLCs, Triple Modular Redundancy is the provision of three micro processors instead of one in situations where continuing functioning has to be ensured.
Trunkwire A trunkwire will be possible for a series of digital devices. Such a series will be able to use a single wire, rather than the multiplicity of wires used on analogue devices which all require separate wiring.
Web Inspection In the paper industry cameras are inserted to monitor the sheet for visual defects.
World FIP The fieldbus adopted in France. FIP stands for factory instrument protocol. The Profibus organisation is seeking to integrate this with the common European Profibus PA protocol.
 
 
 
   
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