| 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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