General Industry Glossary of Terms


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A/D Converter (Also A/D or ADC)

Short for analog-to-digital converter. Converts real-world analog signals into a digital format that can be processed by a computer.

Abnormal Failure

Abnormal Failure: An artificially induced failure of a component, usually as a result of "abnormals" testing for regulatory agency safety compliance.

Absolute Move

1) A move to a specified absolute position relative to a fixed zero position as a reference point.
2) Contrasted with incremental move

Absolute Position

1) Position referenced to a fixed zero position.
2) Contrasted with incremental position

Absolute Pressure

Gage pressure plus atmospheric pressure.

Absolute Pressure Transducer

A transducer that has an internal reference chamber sealed at or close to 0 psia (full vacuum) and normally provides increasing output voltage for increases in pressure.

Absolute Zero

Temperature at which thermal energy is at a minimum. Defined as 0 Kelvin, calculated to be -273.15 ?C or -459.67?F.

AC Linearity

A dynamic measurement of how well an A/D performs. In an ideal A/D converter, a pure sine wave on the analog input appears at the digital output as a pure (sampled) sine wave. In the real world, however, spurious signals due to nonlinear distortion witin the A/D appear in the digital output. These anomalies are usually combinations of harmonics of the fundamental and intermodulation products, produced when the fundamental and its harmonics beat with the sampled frequency.


The first derivative of velocity with respect to time. Units expressed in "g".


A transducer which converts mechanical motion into an electrical signal that is proportional to the acceleration value of the motion.

Access Protocol

A transducer which converts mechanical motion into an electrical signal that is proportional to the acceleration value of the motion.


The combined error of nonlinearity, repeatability, and hysteresis expressed as a percent of full scale output.

Acquisition Time

A defined set of procedures that function as an interface between a user and a network and enable the user to employ the services of that network.


in a closed-loop control system, that part of the final control element that translates the control signal into action by the control device.


An identification (number, name, or label) that uniquely identifies a computer register, memory location, or storage device.

Adjustable Speed

The concept of varying the speed of a motor, either manually or automatically. The desired operating speed (set speed) is relatively constant regardless of load.


Automated Instrument Manager


a set of rules specifying a sequence of actions taken to solve a problem.

Ampere (amp)

A unit used to define the rate of flow of electricity (current) in a circuit.


Automated mapping/facilities maintenance; see also FM/AM


A device which draws power from a source other than the input signal and which produces as an output an enlarged reproduction of the essential features of its input.

Analog Circuit

1) A circuit in which the signal can vary continuously between specified limits.
2) A circuit that provides a continuous function.

Analog Input Module

An I/O module that contains circuits that convert analog dc input signals to digital values that can be manipulated by the processor. By implication, these analog inputs are usually direct (i.e., a data table value directly reflects the analog signal value).

Analog Output Module

An I/O module that contains circuits that output an analog dc signal proportional to a digital value transferred to the module from the processor. By implication, these analog outputs are usually direct (i.e., a data table value directly controls the analog signal value).

Analog signal

any form of data transmission where the pneumatic, mechanical, or electrical energy signal is varied in direct proportion to the intensity of the physical quantity, property, or condition represented.


Unit of measure for the wavelength of light (10A = 1nm).


American National Standards Institute: The institute that co-ordinates the development of standards and guidelines used in the United States. ANSI is the only United States representative to the international Standards Organization.


Application Platform is the part of the Systems Management Services (SMS) infrastructure that provides an environment for management application development, debugging, and execution.


Application Program Interface: The interface between the applications software and the application platform.

Application software

a program that performs a service specific or solves a particular problem to an end user??s needs.


a structured set of protocols implementing the functions of the system.

Artificial intelligence

The concept that computers can be programmed to assume capabilities such as learning, reasoning, adaptation and self-correction.


Automated Storage and Retrieval Systems.


the American Standard Code for Information Interchange is a binary character code used to represent a character in a computer. It consists of 128 seven-bit codes for upper and lower case letters, numbers, punctuation, and special communication control characters.


A program that translates symbolic source code (written in assembly language) into machine instructions (in machine code) by replacing symbolic operation codes with binary operation codes, and symbolic addresses with absolute or relocatable addresses.


A relationship between entities or data elements in a logical data model.

Asynchronous computer

a computer providing operations that are not timed by a master clock. The signal to start an operation is provided by the completion of some operation.

Asynchronous Scanning

A scanning arrangement where two scans (I/O and user program) operate independently of each other with no synchronization, so that any relative timing between the two scans is totally random.


Asynchronous transfer mode; a communications standard


A means of characterizing data on a display device (e.g. intensifying, blinking).


In an SLC controller, the process of transferring contents of the memory module to the processor memory at power up.


1) The conversion to and implementation of procedures, processes or equipment by automated means.
2) Industrial open or closed-loop control system in which manual operation of controls is replaced by servo operation.

Axial Load

A load applied along or parallel to and concentric with the primary axis.


Any movable part of a machine or system that requires controlled motion. Several axes of motion can be combined in a coordinated multiaxis system.

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a wiring board, usually constructed as a printed circuit, used to provide the required connections between logic, memory and I/O modules.


range (usually Hertz) over which a system operates.

Bar coding

an automatic identification technology that encodes data in a printed pattern of varying-width bars and spaces, in accordance with pre-determined rules.

Base Speed

Base speed is the manufacturer's nameplate rating where the motor will develop rated power at rated load and voltage. With dc drives, it is commonly the point where full armature voltage is applied with full-rated field excitation. With ac systems, it is commonly the point where 60Hz is applied to the induction motor.


Beginner's All-Purpose Symbolic Instruction Code, a simple programming language widely used for personal computers.

Batch manufacturing

the technique of manufacturing parts or finished goods in groups, lots, or batches in which each part or finished good in the batch is identical.

Batch processing

is the method adopted when the required product volumes do not allow continuous production of one product on particular machines.

Batch production

refers to the lot size of identical parts produced in a factory. Batch production is the method adopted when the required product volumes are not adequate to permit continuous production of one product on dedicated machines.


A unit of data transmission speed equal to the number of bits (or signal events) per second; 300 baud = 300 bits per second.

Baud rate

a measure of the signalling speed in a digital communication system.


A fixed point of reference or a standard for comparison, used to achieve excellence within the manufacturing firm; an outstanding example, appropriate for use as a model.


An improvement process in which a company or organization compares its performance against best-in-class companies or organizations, determines how those companies or organizations achieved their performance levels, and uses the information to improve its own performance. The subjects that can be benchmarked include strategies, products/programs/services, operations, processes and procedures.

Bill of material

A listing of all the subassemblies, parts, and raw materials that go into a parent assembly.


Refers to base 2 numbering system, in which the only allowable digits are 0 and 1. Pertaining to a condition that has only two possible values or states.

Binary code

A representation of information using a sequence of zeros and ones. The basis for calculations in all digital computers


Acronym for basic input/output system. The commands used to tell a CPU how it will communicate with the rest of the computer.


A digit in binary notation, e.g., 0 or 1.

Block diagram

An illustration in which essential units of any system are drawn in the form of blocks and their relationship(s) to each other are indicated by appropriate interconnecting lines. (2) In computer programming or business/manufacturing process flow(s), a graphical representation of data processing or workflow within a system.

Board (card)

1) A printed-circuit board.
2) A printed-circuit-board assembly ?? in the sense that the (printed-circuit) board is physically the main component of a printed-circuit-board assembly.


The natural limits of a process, defined as where the process begins and where the process ends.


LAN Uses frequency division multiplexing to divide a single physical channel into a number of smaller, independent frequency channels to be used to transfer different forms of information.


A conductor, usually composed of some element of carbon, serving to maintain an electrical connection between stationary and moving parts of a machine (i.e.,commutator of a dc motor). This brush is mounted in a spring-loaded holder and positioned tangent to the commutator segments against which it "brushes." Pairs of brushes are equally spaced around the circumference of the commutator.


1) In software terms, a register or group of registers used for temporary storage of data, to compensate for transmission rate differences between the transmitter and receiving device.
2) In hardware terms, an isolating circuit used to avoid the reaction of one circuit with another.


A programming process that takes a user keyboard command (source code) and converts it into hexadecimal format to generate an object code for program execution.


ability to change processors controlling a process (changeover) without affecting the process.


A high-speed pathway shared by signals from several components of a computer.

Bus Network

A network topology that uses a single communications link to connect three or more terminals. Also called a Multi-Drop Network.

Bus Topology

A link topology in which all stations are connected in parallel to a medium. These stations are capable of concurrently receiving a signal transmitted by any other station connected to the medium.


1) A fixed number of bits, often corresponding to a single character and processed as a unit.
2) A collection of eight bits capable of representing an alphanumeric or special character.

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C, C+, C++

a high-level language that can be used in application software.


Computer-Aided Design is the use of high-resolution graphics in a wide range of design activities, allowing quick evaluation and modification.


Computer-Aided Engineering is the analysis of a design for basic error-checking, or to optimize manufacturability.


the process of determining the capacity or scale graduations of a measuring instrument.


Computer-Aided Manufacturing is the use of computer technology to generate data to control part or all of a manufacturing process.


Controller area network


Computer-Aided Process Planning is a management framework for data that assists the functions of process planning in manufacturing.


Computer-Aided Software Engineering is the use of object-oriented programming and other techniques to streamline generation of programming code.


Compact-Disc, Read-Only Memory systems use digitized multimedia signals to recreate text, video, and graphics. A data-storage medium using the same physical format as audio compact discs. CD-ROM is popular for distribution of large databases, software, and especially multimedia applications.

Cell control

a manufacturing unit consisting of two or more workstations or machines and the materials, transport mechanisms and storage buffers that interconnect them.

Changeover time

The time required to modify a system or workstation, usually including both tear-down time for the existing condition and set-up time for the new condition. Typically associated with a switch to new product.


Computer-Integrated Manufacturing is the increased integration of business and manufacturing functions through application of information technology; the use of computers in all aspects of manufacturing, with integration of functions and control in a hierarchy of computer systems.


a communications path between two points.

Circuit Switching

A method of establishing a dedicated communications path between two or more locations through one or more switching nodes. Data is sent in a continuous stream; the data rate is constant; the delay is constant and limited to propagation times; and a dedicated end to end path remains in effect until the communication is terminated.

Circular interpolation

Coordination of two independent motion axes to produce an apparent circular motion. It's done through a series of straight line approximations via software algorithms.


a user's workstation in a client/server architecture. The client serves as a user interface processing time-consuming tasks to distribute the computing load from the server.

Client-Server Network

A network that uses a central computer (server) to store data that is accessed from other computers on the network (clients).

Client/server architecture

an approach to co-operative processing, where the functions of an application are shared between multiple computers on a network.


The term applied to the phenomenon which occurs when an output signal is limited in some way by the full range of an amplifier, ADC or other device. When this occurs, the signal is flattened at the peak values, the signal approaches the shape of a square wave, and high frequency components are introduced. Clipping may be hard, as is the case when the signal is strictly limited at some level; or it may be soft, in which case the clipping signal continues to follow the input at some reduced gain.


loop control -any system in which part of the output is fed back to the input to effect a regulatory action, and in which the controlled quantity is measured and compared with a standard representing the desired performance. Any deviation from the standard is fed back into the control system in such a sense as to reduce the deviation.

Closeness of Control

Total temperature variation from a desired set point of system. Expressed as "closeness of control" is ±2?C or a system bandwidth with 4?C, also referred to as amplitude of deviation.


Computer Numerical Control allows the control of motion in an accurate and programmable manner through use of a dedicated computer within a numerical control unit, with a capability of local data input such that machine tools are freed from the need for "hard-wired" controllers.

Coaxial cable

a physical network medium that offers large bandwidth and the ability to support high data rates with immunity to electrical interference and a low incidence of errors.


Common Business Oriented Language is a programming language commonly used for data processing.

Colour Code

The ANSI established colour code for thermocouple wires in the negative lead is always red. Colour Code for base metal thermocouples is yellow for Type K, black for Type J, purple for Type E and blue for Type T.


Component object model

Common Cause

Predictable normal random variation present in every process due to the combination of existing inputs.

Common Mode

The output form or type of control action used by a temperature controller to control temperature, i.e. on/off, time proportioning, PID.

Common Mode Rejection Ratio

The ability of an instrument to reject interference from a common voltage at its input terminals with relation to ground. Usually expressed in db (decibels).

Communication link

the mechanism for information transmission.


Sequential excitation of motor windings to maintain the relative phase angle between the rotor and stator magnetic fields, within specified limits, to control motor output. In brush dc motors, this function is accomplished by a mechanical commutator and carbon brushes; in brushless motors, it's done electronically using rotor position feedback.


the ability for two devices to communicate together of software to run on a particular hardware platform.

Compensating Alloys

Alloys used to connect thermocouples to Instrumentation. These alloys are selected to have similar thermal electric properties as the thermocouple alloys (however, only over a very limited temperature range).


An addition of specific materials or devices to counteract a known error.


A program that translates a high-level language program into a computer's machine code or some other low-level language.

Concurrent engineering

The restructuring of the engineering process so that the input of all concerned parties, including manufacturing, sales and even customers, are heard from during a project's conception.


The collective opinion of a group on the discussion of an issue until all agree or everyone is willing to accept the decision.

Continous process control

The use of transducers (sensors) to monitor a process and make automatic changes in operations through the design of appropriate feedback control loops; such devices historically have been mechanical or electromechanical, but now widely use computers and centralized control.

Continual Improvement

Refers to the philosophy whereby every system or process within the organization is subject to continual scrutiny and improvement. Continual improvement is the antithesis of the philosophy which says, "If it ain't broke, don't fix it." Continual improvement requires that "If it ain't broke, it can be made better."

Continuous-flow production

A process industry production method.

Control circuit

a circuit in a piece of equipment or an electrical circuit that carries the signal determining the control action, as distinct from the power used to energize the various components.

Control Mode

The output form or type of control action used by a temperature controller to control temperature, i.e., on/off, time proportioning, PID.

Control system

a system to guide or manipulate various elements in order to achieve a prescribed result.


a device or program that operates automatically to regulate a controlled variable.


A measurement of the quantity of electrical charge, usually expressed as pico coulomb (10-12 coulombs).


The number of time intervals counted by the dual-slope A/D converter and displayed as the reading of the panel meter, before addition of the decimal point


the Central Processing Unit controls the operation of the computer system and executes the arithmetic and logic functions of a particular program.


In warehouse management, sending parts from receiving directly to shipping to be placed in outgoing orders. Crossdocking allows orders to be filled quickly and precludes parts from staying in a warehouse long enough to be counted as inventory.


Canadian Standards Association.

Cycle Time

The interval required to complete a task, or function, starting from the beginning of the first step until the completion of the last.

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Converter Short for digital-to-analog converter. This is a device that changes a digitally coded word into its equivalent quantized analog voltage or current. Just like the A/D device, there are very high-speed D/A's available, capable of converting at data rates up to 1 GHz.

Dark factory

A completely automated factory floor with no labour.


all information of computer operations directed by the detailed instructions of the program.

Data acquisition system

any instrument or computer that acquires data from sensors via amplifiers, multiplexers, and any necessary analog to digital converters.

Data collection

the act of bringing data from remote points to a central location, and its organization into understandable information.

Data element

A single, atomic piece of data that cannot be subdivided and still retain any meaning. The terms "data item" and "field" are often used synonymously with data element.

Data Management

The process by which the reliability, timeliness and accessibility of an organization??s data base is assured.

Data space

where data reside.

Data warehouse

A database for query and analysis, as opposed to a database for processing transactions. Separating the two functions improves flexibility and performance.


a collection of structured information.

dB (Decibel)

20 times the log to the base 10 of the ratio of two voltages. Every 20 dBs correspond to a voltage ratio of 10, every 10 dBs to a voltage ratio of 3.162. For instance, a CMR of 120 dB provides voltage noise rejection of 1,000,000/1. An NMR of 70 dB provides voltage noise rejection of 3,162/1.


Database Management Systems access data stored in a database and present multiple data views to end users and application programmers.


Direct current; an electric current flowing in one direction only and substantially constant in value.


Distributed COM


Distributed Control System is a real-time control system for continuous and batch process applications.


In process control, a range in which an input signal may be varied, without initiating a change in output signal.


A unit (dB) for measuring the relative strength of signal power. The number of decibels equals ten times the logarith (base 10) of the ration of the measured signal power to a reference power. One tenth of a bell.


support tools PC-, client-, or application server-based systems that use memory-based processing to perform rapid simulations using data drawn from business-transaction processing systems such as enterprise resources planning. The simulations optimize such things as production or distribution plans based on variously weighted goals, such as low cost or on-time delivery. Management then can decide which scenario best balances the many competing claims it must address when running a business.

Default value

The option taken by a computer in the event of the omission of a definite instruction or action.


Level of power supplied from the electric system during a specific period of time.

Demand management

see Forecasting.

Demand-side management (DSM)

Measures taken by a utility to influence the level or timing of a customer's energy demand. By optimizing the use of existing utility assets, DSM programs enable utilities to defer expenditures for adding new generating capacity.


Design and engineering practice


The systematic process of introducing an activity or process to all applicable areas of an organization.

Deterministic model

A mathematical model that, given a set of input data, produces a single output or a single set of outputs.

Development tools

The raw materials by which programmers create custom-built enterprise software.


The difference between an observation and a fixed value.

Device driver

Software that controls a computer peripheral, sometimes referred to as the interface software.


For an on/off controller, it refers to the temperature difference between the temperature at which the controller turns heat off and the temperature at which the heat is turned back on. It is expressed in degrees.

Digital Output

An output signal which represents the size of an input in the form of a series of discrete quantities.


A set of German standards recognized throughout the world. The 1/8 DIN standard for panel meters specifies an outer bezel dimension of 96 x 48 mm and a panel cutout of 92 x 45 mm.

Discrete event simulation

A technique often used by engineers in the design and modification of production systems, whereby models output statistical estimates of performance, using graphic animation to help create a greater understanding of system dynamics.

Discrete manufacturing

Production of distinct items such as automobiles and computers.

Discrete part manufacturing

a manufacturing process that produces discrete parts in comparatively small lots or batches of from one to perhaps 50,000.

Disk mirroring

data protection by duplication on disk drives.


The measured distance traveled by a point from its position at rest. Peak to peak displacement is the total measured movement of a vibrating point between its positive and negative extremes. Measurement units expressed as inches or millinches.

Distributed processing

the physical and/or logical connectivity of hardware, software, information, and load sharing.

Distributed system

a system consisting of a group of connected computers sharing software, information or load.

Distribution management

Systems that determine optimal quantities of each product to be made at each plant and to be distributed to each warehouse, such that manufacturing and distribution costs are minimized and customer demands are met.


The characteristic of a workforce which is a result of individual differences between its members. Specific differences may include: gender, workforce minorities, or individual disabilities. Workforce diversity is a major organizational strength when the knowledge, abilities and strengths of individual workers are recognized and respected.


see Document management system

Document management system

Allows users to store, search, and manipulate documents electronically and to maintain a library of text and images in a compact space. Most systems also provide a means for passing documents across a network.


periods where computers, equipment, or manufacturing systems are not available to perform work.


A common occurrence in time-proportional controllers. It refers to the difference in temperature between the set point and where the system temperature actually stabilizes due to the time-proportioning action of the controller.


Digital signal processing or digital signal processor.

Dual Element Sensor

A sensor assembly with two independent sensing elements.

Dynamic dispatching

in real time, as it occurs, status changes such as work computed, operational problem, priority changes, updates the entire factory floor automatically rescheduling ALL operations for ALL released jobs to reflect those changes.

Dynamic scheduling

Software that allows refinement of production schedules as conditions change. In a client/server configuration, the scheduler takes data from an MRP II system and runs multiple simulations to find the optimal scheduling solution.

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Electronic Data Interchange is a standard for automated exchange of business documents that allows purchasers and suppliers to exchange digital paperwork, such as purchase orders, invoices and other business documents, and to perform electronic funds transfers.


Engineering Document Management System.


Electrically Eraseable Programmable Read Only Memory.


Meeting agreed-upon requirements for supplier inputs and customer outputs.


Minimizing time and/or other resources spent on activities which do not add value.


Equipment identification system

Employee Involvement

A practice within an organization whereby employees regularly participate in making decisions on how their work is done, including making suggestions for improvement, planning, goal setting and monitoring performance.


A condition whereby employees have the authority to make decisions and take action on their own without prior approval.


a surrounding case that protects equipment from its environment, and protects personnel against contact with the enclosed equipment.


A feedback device that translates mechanical motion into electrical signals indicative of actuator position. Incremental and absolute encoders are common varieties; as the names imply, their output indicates incremental or absolute changes of position.


The process of putting information into digital format.

End user interface (EUI)

interface through which an application program provides information to people.


Something about which information is stored, either tangible or not, such as an employee or a part on the one hand, or an event or abstract concept on the other.


Enterprise Resource Planning is recognized as a logistical extension of MRP.


The standard for local communications networks developed jointly by Digital Equipment Corp., Xerox, and Intel. Ethernet baseband coaxial cable transmits data at speeds up to 10 megabits per second. Ethernet is used as the underlying transport vehicle by several upper-level protocols, including TCP/IP.

Expert system

software that applies knowledge and reasoning techniques that involve rules and heuristics to solve problems normally requiring the abilities of human experts.

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A three- or four- sided polygon element that represents a piece of a 3D polygonal mesh model. Triangular facets are used in STL files.


A person knowledgeable in process improvement, problem solving and group dynamics who assists teams and team leaders by serving as coach, communicator, coordinator, promoter and teacher as needed.

Fault tolerance

the ability to execute tasks regardless of the failure of strategic components.


The return of part of the output of a machine, process, or system to the computer as input for another phase, especially for self-correction or control purposes.


fiber distributed data interface; a communications standard for networks


A method that "precompensates" a control loop for known errors due to motor, drive, or load characteristics to improve response. It depends only on the command, not the measured error.


See Free-Form Fabrication.

Fiber optics

a data transmission medium using light conducted through glass or plastic fibers. A fiber-optic cable has cores capable of conducting modulated light signals by internal reflection.


The predetermined section of a record that contains a specific portion of information.


a standard for digital communications between field devices and their control systems. Devices include flow, temperature, and pressure sensors and actuators of valves and motors.


facilities information management

Finite scheduling

Scheduling software that takes into account that manufacturing resources-such as production capacity-are finite. Other constraints might include personnel, regulatory pressures, or materials, as in traditional MRP II.

Flexible automation

The ability to switch quickly from one product to another by shortening setup times.

Flexible manufacturing system

integrates combinations of various types of capital equipment, primarily in metal-cutting applications. A system is flexible if it is capable of processing a number of different work-pieces simultaneously and automatically, with the machines in the system carrying out the system??s operation in any sequence.

Flow Rate

Actual speed or velocity of fluid movement


automated mapping and facilities management


Flexible Machine Centre is usually an automated system comprising CNC machines, with robots loading and unloading parts conveyed into and through the system.


See Flexible manufacturing system.


Systems that predict levels of weekly or monthly product activity over a time horizon, typically two years. General availability of PCs and user-friendly application programs mean forecasting can be done by educated generalists, particularly those with the best understanding of the factors impacting demand.


FORmula TRANslation is a procedure-oriented programming language used to solve engineering, mathematical and scientific problems.

Free-Form Fabrication

Another (perhaps more descriptive) name for Rapid Prototyping.


The number of recurrences of a periodic phenomenon in a unit of time, usually electronically specified in hertz (Hz)??i.e., one cycle per second equals one hertz.

Front end

Shorthand term for the operator interface or application-specific aspects of a program.

Function (1)

The characteristic actions, operations, or kind of work a person or thing is supposed to perform, e.g., the engineering function or the material-handling function. (2) The operation called for in a computer software instruction.

Fuzzy logic

a method used to model linguistic expressions that have non-binary truth values. It has been used with PID algorithms in process control, especially where process relationships are non-linear.

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The force of acceleration due to gravity equal to 32.1739 ft/sec2 or 386 in./sec2.


A measuring device or measuring instrument.


The ratio of the magnitude of the output signal with respect to that of the input signal.

Gain error

The "gain" of an analog input or output is the scale factor that provides the nominal conversion relationship. Typically, this is the slope of the line when analog voltage or current is plotted versus the corresponding digital values. Gain error is the deviation of the scale factor or slope of the line from the ideal or nominal gain value. Gain error is expressed in percent of the input or output value.


1) A logic element that blocks or passes a signal, depending on the status of specified input signals.
2) The control element of an SCR or of some other solid-state devices.


a special node that interfaces two or more dissimilar networks, providing protocol translation between the networks.

Group technology

a coding and classification system used in CAD for combining similar, often-used parts into families. This allows them to be retrieved, processed, and eventually fabricated, in an efficient, economical batch mode.


a type of software designed to raise the productivity of people working in groups and thought to have application in both engineering and production functions.


a Graphical User Interface is characterized by using windows, icons and menus.

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Hand shaking

contact among or between CPUs for identification.


An interface procedure that is based on status/data signals that assure orderly data transfer as opposed to asynchronous exchange.


the physical, manufactured components of a computer system, such as the circuit boards, CRT, keyboard, and chassis.

Harmonic distortion

Continuous distortion of the normal sine wave, occurring at frequencies between 60 Hz and 3 kHz.


Describes an approach based on common sense rules and trial and error, rather than on comprehensive theory.

High-level language

A problem-oriented programming language in which each instruction may be equivalent to several machine-code instructions.


Human-machine interface


1) A central controlling computer in a network system.
2) Any device on a network system that provides a controlling function to another device on the network.
3) Any intelligent device for which another device is providing a communication interface to a network.

Host computer

the primary computer in a multi-processor network that issues commands, accesses the most important data, and is the most versatile processing element in the system.

Hot swap

exchange of components during operation.


Hyper text markup language


An interactive on-line documentation technique that allows users to select ?? typically via a mouse click ?? certain words or phrases to immediately link to information related to the selected item.


1) The effect of residual magnetism whereby the magnetization of a ferrous substance lags the magnetizing force because of molecular friction.
2) The property of magnetic material that causes the magnetic induction for a given magnetizing force to depend upon the previous conditions of magnetization.
3) A form of nonlinearity in which the response of a circuit to a particular set of input conditions depends not only on the instantaneous values of those conditions, but also on the immediate past of the input and output signals.

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Stands for "Input/Output," in automation, a term encompassing all physical connection points between a control system and the sensors and actuators of the "real world."


Initial Graphics Exchange Specification. IGES is an industry standard format for exchanging CAD data between systems.

Image processing

Techniques for filtering, storing, and retrieving images, as well as for processing pictorial information by computer.


An object implemented by some relational database software that controls the order in which a table is accessed or stored.


An electronic unit that converts high-level commands from a host computer, PLC, or operator panel into step and direction pulses needed by a stepping motor driver.


An identified measure of a process.

Information System

The information system manages the scope, validity, reliability, selection and maintenance of quality and performance data and information. The system also provides comparative information and benchmarks. The data and information is then used to monitor and improve the integrated systems.

Input signal

A signal applied to a device, element, or system.


the term for any item of electrical or electronic equipment designed to carry out a specific function or set of functions. A device for measuring the value of an observable attribute. The instrument may also control the value.


systems of instruments used to observe and control a physical object or process.

Integrated circuit

A small, complete circuit of interconnected semiconductor devices such as transistors, capacitors, and resistors printed in a single silicon chip.


a shared boundary between two pieces of equipment. Hardware and associated software needed to enable one device to communicate with another.


A device that prevents a machine from initiating an operation until a condition or set of conditions is fulfilled.


The ability of computers on a network to share application software.

Intrinsically Safe

An instrument which will not produce any spark or thermal effects under normal or abnormal conditions that will ignite a specified gas mixture.

Inventory management

the systematic determination of items and quantities to be ordered; the co-ordination of order release and order due dates; changes in the required quantities; and the rescheduling of planned orders.

IOBASE-T Ethernet

A version of Ethernet that operates over twisted-pair wire at a speed of 10 Mb/s. IOBASE-T networks with more than two terminals must use an Ethernet hub and a star topology.


Industry Standard Architecture (PC-AT Bus) or Instrument Society of America.


International Standards Organization.

Island of automation

A stand-alone pocket of automation, such as a robot, CAD/CAM system or CNC machine, that is not connected into a cohesive system.


The reduction of the capacity of a system to respond to an external force by use of resilient isolating materials.

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Principally a programming language, but it has been designed by Sun Microsystems to function as a complete computer operating system. The purpose of the language has been twofold: to create a single standard that will run on a variety of competing computer systems, and to solve vexing computer security problems introduced by the widespread reliance on computer networks, which are vulnerable to malicious programs like viruses.


Just-in-Time is an approach to manufacturing where each operation is closely synchronized with subsequent operations.


To generate motion (continuous or incremental) whenever an operator-activated switch is closed.


The basic unit of thermal energy.

Jump instruction

An instruction that causes the processor to deviate from executing instructions in order, by jumping to another place in the program.


A short conductor with which you can connect 2 points.


The point in a thermocouple where the two dissimilar metals are joined.

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This is the Japanese word for improvement. Kaizen implies more than improvement in basic production processes. Kaizen represents a philosophy whereby an organization, and the individuals within it, undertake continual improvements of all aspects of organizational life.


The Japanese methodology for achieving JIT, often involving the use of "kanbans," or cards, to indicate parts status.

Kelvin Symbol K.

The unit of absolute or thermodynamic temperature scale based upon the Celsius scale with 100 units between the ice point and boiling point of water. 0?C = 273.15K (there is no degree (?) symbol used with the Kelvin scale).

Key Performance Indicators

Measurement(s) which determine if the critical success factor was successfully achieved.


Devices that allow only selected pairs of mating connectors to be plugged into each other.

Kilowatt (kw)

Equivalent to 1000 watts.

Kilowatt Hour (kwh)

1000 watthours. Kilovolt amperes (kva): 1000 volt amps.

Kinetic energy

The energy of motion of a moving body.


Kraftwerk kennzeichen system

Knowledge - based system

software that uses artificial intelligence techniques and a base of information about a specialized activity to control systems or operations.


Kilovolt amperes (1000-volt amps).

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Ladder logic

symbolic representation illustrates schematically the functions of a control circuit. The power lines form the sides of a ladder-like structure, with the program elements arranged to form the rungs.


1) A time delay between the output of a signal and the response of the instrument to which the signal is sent.
2) A time relationship between two waveforms where a fixed reference point on one wave occurs after the same point of the reference wave.


Local Area Network. A network that takes advantage of the proximity of computers to offer relatively efficient, higher-speed communications than long-haul or wide-area networks.


Link Access Protocol.


Light-Emitting Diodes are solid-state devices that radiate in the visible region. They are used in alphanumeric displays and as indicator or wiring lights.

Life Cycle

The minimum number of pressure cycles the transducer can endure and still remain within a specified tolerance.

Limit switch

an electromechanical device positioned to be actuated when a certain motion limit occurs, thereby deactivating the actuator causing the motion.

Limits of Error

A tolerance band for the thermal electric response of thermocouple wire expressed in degrees or percentage defined by ANSI specification MC-96.1 (1975).


said of any device or motion where the effect is exactly proportional to the cause.

Linear load

A predictable nonprocess energy load that has a profile that changes with time and condition.

Linear programming

A management technique applied to problems in which a linear function of a number of variables is subject to a number of constraints in the form of linear inequalities. Developed as a technique for planning the diversified activities of the U.S. Air Force, the process generates several different plans, requiring a criterion for deciding which plan is best and how to find it. Mathematically, linear programming is the analysis of problems in which a linear function of a number of variables is to be maximized or minimized when those variables are subject to a number of restraints in the form of linear inequalities.


The maximum deviation of the calibration curve from a straight line between zero and full scale, expressed as a percent of full scale output and measured on increasing measured only.

Load cell

a transducer for the measurement of force or weight. Action is based on strain gages mounted within the cell on a force beam.

Loop bandwith

Maximum rate at which a control loop can respond to a change in a control parameter. It's indicative of loop performance and is expressed in Hertz (Hz).

Loop Resistance

The total resistance of a thermocouple circuit caused by the resistance of the thermocouple wire. Usually used in reference to analog pyrometers which have typical loop resistance requirements of 10 ohms.


Directing signals back toward the transmitting terminal at some point along the communications path. Used as a method of troubleshooting.

LS-TTL Compatible

For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5 V which can source 20 µA, and a logic 0 is obtained for inputs of 0 to 0.8 V which can sink 400 µA. For digital output signals, a logic 1 is represented by 2.4 to 5.5 V with a current source capability of at least 400 µA; and a logic 0 is represented by 0 to 0.6 V with a current sink capability of at least 16 MA. "LS" stands for low-power Schottky.

LS-TTL Unit Load

A load with LS-TTL voltage levels, which will draw 20 µA for a logic 1 and -400 µA for a logic 0.

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Machine vision

1) A computer perception of a visually based sensory output used to produce a concise description of an image.
2) Devices used for optical non-contact sensing to receive and interpret automatically an image of a real scene in order to obtain information or to control a process.


A kind of computer shorthand that reduces many commands to one, making it easy to activate frequently-used functions.

Magnetic contactor

A device used to open or close.


products manufactured to specific customer order configuration and delivery time specifications.


products manufactured for finished-goods storage before a customer order arrives.

Management by Fact

A key focus of total quality management. Means all employees manage the work they do by collecting objective data and making decisions based on this information.

Manual Reset (Adjustment)

The adjustment on a proportioning controller which shifts the proportioning band in relationship to the set point to eliminate droop or offset errors.

Manual Reset (Switch)

The switch in a limit controller that manually resets the controller after the limit has been exceeded.


Manufacturing Automation Protocol is a specification for a suite of communication standards developed initially by General Motors and based on the OSI reference model.

Mass Flow Rate

Volumetric flowrate times density, i.e. pounds per hour or kilograms per minute.

Materials handling

the process, which includes mechanical handling, of transporting and positioning raw materials, semi-finished and finished products in connection with industrial operations, by conveyors, cranes, trucks, hopper feeds, and other equipment.

Maximum Operating Temperature

The maximum temperature at which an instrument or sensor can be safely operated.


Manufacturing Execution Systems are plant-floor management systems that allow downloading recipes and work schedules, and uploading production results, thereby bridging the gap between business and plant-floor or process control systems.


One thousandth of an amp, 10-3 amps, symbol mA.


Unit of electromotive force. It is the difference in potential required to make a current of 1 millampere flow through a resistance of 1 ohm; one thousandth of a volt, symbol mV.


Management Information Systems are computerized networks used in effectively structuring critical information in a form usable for identification of inefficiencies.


the recreation of an event or object in a controlled environment in order to predict results from that event or object.


a MODulator-DEModulator converts data to a form compatible for sending and receiving on transmission facilities.

Motion Control

the application of moving parts in industrial settings including sequencing, speed control, point-to-point control, and incremental motion. Control options include timers and counters, chip-level and board-level computers, PLCs, and pneumatic sequencers.

Motion profile

The velocity versus time (or position) relationship of the move made by a motion axis.


Materials Requirements Planning.


Manufacturing Resource Planning is a software tool which enables a manufacturer to plan, allocate and track material and financial resources for a production process.

Machine language

Binary instructions to a computer that it can execute directly, without translation.


A technique which allows different input (or output) signals to use the same lines at different times, controlled by an external signal. Multiplexing is used to save on wiring and I/O ports.


an I/O device that routes data from several sources to a common destination.

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Numerical Control is a technique of operating machine tools or similar equipment in which motion is generated in response to numerically ordered commands generated by CAD systems, punched tapes, or other communication media.


A standard from the National Electrical Manufacturers Association, which defines enclosures with protection against dirt, dust, splashes by non-corrosive liquids, and salt spray.


A standard from the National Electrical Manufacturers Association, which defines enclosures intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water.


A standard from the National Electrical Manufacturers Association, which defines explosion-proof enclosures for use in locations classified as Class I, Groups A, B, C or D, as specified in the National Electrical Code.

NEMA-Size Case

An older US case standard for panel meters, which requires a panel cutout of 3.93 x 1.69 inches.


1) Any system of computers and peripherals.
2) In an electrical or hydraulic circuit, any combination of circuit elements.


A terminal on a data communications network.


An unwanted electrical interference on the signal wires.

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Optical Character Recognition is the machine recognition of characters by light-sensing methods.


an Original Equipment Manufacturer provides final systems made from assemblies and subassemblies from other manufacturers.


The difference in temperature between the set point and the actual process temperature. Also, referred to as droop.


operator interface; the hardware and software that shows an operator the state of a process


Object linking and embedding

On/off Controller

A controller whose action is fully on or fully off.


Object Oriented Programming


OLE for process control


OPC data access


OPC data exchange

Open Circuit

The lack of electrical contact in any part of the measuring circuit. An open circuit is usually characterized by rapid large jumps in displayed potential, followed by an off-scale reading.

Open systems

an approach to computing that allows the interconnectability of systems based on compliance with established standards.

Operating system

a structured set of system programs that controls the activities of a computer system by managing memory, tasks and communications.

Operator interface

a physical link between the human operator and a computer system, typically consisting of a graphical representation.


A process of orchestrating the efforts of all components toward achievement of the stated aim so everyone gains.


The electrical signal measured at the output terminals which is produced by an applied input to a transducer.


Things and information which are the end result of an activity (product, reports, services, information, etc.)


A system response where the output or result exceeds the desired value.

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The establishment of a long term relationship between two parties characterized by teamwork and mutual trust, allowing both parties to focus on the needs of a mutual customer or client/constituent. Partners share risks as well as benefits. Partnering arrangements can be with labor, management, employees, suppliers, government and educational institutions.


a Personal Computer.


Process control system

pH Junctions

The Junction of a reference electrode or combination electrode is a permeable membrane through which the fill solution escapes (called the liquid junction).


Proportional, integral, derivative. A three mode control action where the controller has time proportioning, integral (auto reset) and derivative rate action.


Stands for "Programmable Logic Controller", a microprocessor-based system used for controlling industrial machinery. These typically accept plug-in Input/Output modules for making connection to sensors and actuators. Most PLCs are programmed using a visual programming technique called "Relay Ladder Logic", developed in the 1960s.


Plant numbering system


The ability to use and migrate software across different platforms.


1) A variable resistor often used to control a circuit.
2) A balancing bridge used to measure voltage.

Power Supply

A separate unit or part of a circuit that supplies power to the rest of the circuit or to a system.

Primary Axis

The axis along which the transducer is designed to be loaded; normally its geometric centerline.


An opportunity for improvement or undesirable condition, often manifested by symptoms, created by root causes which must be systematically identified and eliminated to control the problem.


Step-by-step tasks which are necessary to meet standards; a method or manner of proceeding. How to meet standards.


A systematic and defined method of doing something. A process generally involves a number of steps or operations.

Process control

Automatic monitoring and control of a process by an instrument or system configured or programmed to respond appropriately to process feedback.

Process Management Systems

The process management system is the system of processes that are designed and delivered to support the quality integrated system.

Process simulation

Use of a mathematical model by a computer program to implement different process design scenarios with real-time feedback.

Production control

Systematic planning, co-ordination and direction of all manufacturing activities to ensure that products are made on-time, of adequate quality, and at reasonable cost.


An agreed set of rules to allow data to be transferred among systems.

Prototype tooling

Molds, dies, and other devices used to produce prototypes; sometimes referred to as soft tooling.

Proximity switch

A device that senses the presence or absence of an object without physical contact and that in response closes or opens circuit contacts.

Pulse-width modulation

A switch-mode control method used in amplifiers and drivers to control motor voltage and current to obtain higher efficiency than linear control. PWM refers to variable on/off times (or width) of the voltage pulses applied to the transistors.

Push button

A master switch having a manually operable plunger or button for actuating the switch.

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A technique that separates signal channels by 90? (electrical) in feedback devices. It is used with encoders and resolvers to detect direction of motion.

Quality Assessment

The operational techniques and activities used to evaluate the quality of processes, practices, programs, products and service.

Quality circle

A small group of people who normally work as a unit and meet frequently for the purpose of uncovering and solving problems with the quality of the items produced, process capability or process control.

Quality Control

The operational techniques and activities used to ensure that quality standards are met.

Quality Values

The principles and beliefs that guide an organization and its people toward the accomplishment of its vision, mission and quality goals.


A coding scheme that uses four different voltage levels to represent information, used over the local loop with basic ISDN.

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Random Access Memory is the portion of memory with the capability to both read and write information.

Rapid prototyping

A series of approaches to obtaining an initial or prototype of a part or assembly quickly. See, for example, stereolithography.

Real time

The current time or moment when a process or event is occurring.

Real-time system

Use of precise timing in controlling an event typically consisting of multiple changing variables.

Recovery Time

The length of time which it takes a transducer to return to normal after applying a proof pressure.


Duplication to enhance reliability.


An electromechanical device for remote or automatic control that is actuated by variation in conditions of an electric current. The relay operates other devices in the same or a different circuit.

Relay Ladder Logic

This programming language expresses a program as a series of "coils" and "contacts", simulating the operation of electromechanical relays. The resultant program is the equivalent of a boolean equation, which is executed continuously in a combinatorial manner. The advantage of this language is the familiarity many electricians have with the simple operation of relays. Disadvantages include the complexity of large, cross-connected programs, and the difficulty of expressing such non-binary functions as motion control and analog I/O. An alternative technique now being widely used is State Language control.


1) Customers have requirements or needs. If organizations are listening to customers, they will clearly identify customer requirements. The challenge for organizations is to translate these requirements into precise product/service specification.
2) Laws, statutes, rules, procedures, policies, specification, objectives, goals, operating directives, performance standards, etc.


A position transducer that uses magnetic coupling to measure absolute shaft position during one revolution.


Repeated work required when a process fails or standards are missed.


The study of the design and use of robots, particularly for their use in manufacturing and related processes.


Read Only Memory is memory used for system functions without the capability of being rewritten.


A device that operates at the Network Layer of the OSI model (Layer 3) to connect networks of different architecture by resolving the addressing differences between the networks.


Rapid Prototyping


Remote transmission request

Rule-based system

A functional system in which knowledge is stored in the form of simple if-then or condition-action rules.

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Supervisory Control and Data Acquisition is typically accomplished in industrial settings by means of microcomputers.


To examine data from process sensors for use in calculations. A single sweep of PLC applications program operation. The scan operates the program logic based on I/O status, and then updates the status of inputs and outputs.

Scan time

The time to completely execute a PLC program once, including I/O update. Semiconductor any of a class of solids having higher resistivity than a conductor, but lower resistivity than an insulator. Important semiconductors are silicon, germanium, lead sulphide, selenium, silicon carbide and gallium arsenide. Semiconductor materials are the basis of all integrated circuits.


A transducer whose input is a physical phenomenon and whose output is a quantitative measure of the phenomenon.

Sequence control

The control of a series of machine movements, with the completion of one movement initiating the next. The extent of movements is typically not specified by numerical input data.

Servo mechanism

An automatic, closed-loop motion control system that uses feedback to control a desired output such as position, velocity, or acceleration.


A power-driven mechanism that supplements a primary control operated by a comparatively feeble force (as in a servo mechanism).

Signal conditioning

To make a signal compatible or intelligible to a given device, by processing its form or mode.


Short message service


Statistical Process Control is a quality control method focusing on continuous monitoring of the process rather than the inspection of finished products, with the intent to achieve control of the process and eliminate defective product.


Statistical Quality Control applies statistical techniques to the observed characteristics of a process.


Structured Query Language is a format for accessing data within a relational database management system.


A rule or measure by which a finished product will be measured. A rule established to create a yardstick for measuring or guiding quantity, quality, value, etc. A vehicle for communication.

State Languages

State languages are used primarily for expressing sequences of operations in the real world. Typically, these languages divide a program into a series of "states," or steps - the program executes wholly in one step until some transition event occurs which causes the program to move to a new step. As such, it represents a reasonable way to express the operation of machinery, which itself must transit through a series of mechanical states as it operates. Practical state languages used for automation must allow multitasking, whereby multiple threads of steps may be in operation at once.


A form of rapid prototyping involving the building of solid plastic objects from a CAD file by projecting a laser-generated beam of ultraviolet radiation onto the surface of a vat of photosensitive resin.


A strategy is a series of planned and sequenced tasks, which together allow for achievement of the critical success factor. Strategies must be clearly stated, observable and measurable.

Supervisory control

The use of computers to accomplish operator interface, data acquisition, process monitoring, and some degree of production control.


A device for making, braking, or changing the connections in an electric circuit. In controller practice, a switch is considered to be a device operated by other than magnetic means.

Synchronize a state

Ensuring frequencies of two systems are equal.


A set of well-defined and well-designed processes for meeting the organization??s quality and performance requirements.

Systems integration

The ability of computers, instrumentation and equipment to share data or applications with other components in the same or other functional areas.

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An electromagnetic feedback transducer providing an analog voltage signal proportional to rotational speed.


Timer/Counter Access Terminal.


Transmission Control Protocol/Internet Protocol. A transport layer protocol and a network layer protocol developed by the Department of Defense. This is a commonly used combination for communication within networks and across internetworks.


Any operator interface used to communicate with a computer from a remote location.


A load connected to the end of a transmission line. To avoid signal reflections, it must match the characteristic impedance of the line.

Thread speed

A fixed usually adjustable low speed supplied to provide a convenient method of loading and threading machines. May also be called a preset speed.


The rate at which equipment processes or transmits data.

Thumb-wheel switch

A multi-position rotary switch with a sprocket that is stepped forward or backward by using a finger or thumb to rotate it.

TNS field

Transaction field. A 16-bit field that indicates which message transaction is taking place.


To switch alternately between 2 possible selections.

Toggle switch

A lever-action 2-position switch that snaps into either position.


1) A transmission from the present bus master that grants bus mastership to a station. Mastership is required for a station to originate communication.
2) The logical right to initiate communication.


An instrument used to perform a task or to display collected data. For example; graphs, charts, diagrams, questionnaires, etc.


A turning or twisting force that tends to produce rotation.

Total Quality Management

A systematic customer focused approach to continuous performance improvement. A philosophy and set of guiding principles which represent the foundation for continuously improving the organization through employee involvement. The application of quantitative methods and human resources to improve the materials and services supplied to and by an organization and all the processes within the organization and the degree to which the needs of the customer are met. The integration of fundamental management techniques, existing improvement efforts, and technical tools, under a disciplined approach to focus on continuous improvement.

Touch screen

A CRT screen with which an operator can interact by touching icons displayed on the screen, rather than through a keyboard or mouse


A device that converts signals from one physical form to another.


A momentary deviation in an electrical or mechanical system.

Turn-around time

The time it takes a communication module to receive, interpret, act upon, and reply to an incoming message.

Turnkey system

An application satisfied completely by delivering and installing a system that is ready to operate.

Twinaxial cable

A transmission line made up of a twisted pair of insulated conductors centered inside and insolated from a conductive shield.

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Universal Asynchronous Receiver/Transmitter. An interface device for serial/parallel conversion, buffering, and adding check bits.


Underwriters Laboratories, Inc. An independent laboratory that establishes standards for commercial and industrial products.

Unattended system (bar code)

A bar-code scanner/decoder combination that is triggered, or activated by an external source such as a computer, a programmable controller, or a switch operated automatically by some machine motion.


That condition which exists in a rotor when vibratory force or motion is imparted to its bearings as a result of centrifugal forces.

Unbalance Tolerance

The unbalance tolerance with respect to a radial plane (measuring plane or correction plane) is that amount of unbalance which is specified as the maximum below which the state of unbalance is considered acceptable.

Underflow bit

A bit that is set to indicate that the result of an operation is less than the minimum value that can be contained in a register.

Ungrounded Junction

A form of construction of a thermocouple probe where the hot or measuring junction is fully enclosed by and insulated from the sheath material.

Uni-directional I/O module

An I/O module whose communication with the scanner or processor is uni-directional and therefore uses only an input image area or an output image area.


(bar code) Universal Product Code. A standard bar code type for retail packaging in the United States.

Update time

1) For analog inputs, the time between updates to the memory in the analog module of the digital value representing the analog input signal.
2) For analog outputs, the time from the digital value being received at the analog module to when the analog output signal corresponds to that digital value.


In a manufacturing system, the passing of plant-floor information, such as production results, upward through the CIM hierarchy.

Upper nibble

The four most-significant bits of a byte.


An Uninterruptible Power Supply is used to ameliorate the effects of poor electrical power quality, including voltage anomalies, high-frequency noise, or ground loops. A UPS is especially applicable where power outages of over a half-second duration are possible.


Universal synchronous/asynchronous receiver/transmitter. A UART with the added capability for synchronous data communication.

Utility software

A program or routine, such as an editor or debugger, designed to perform a particular function of general usefulness.

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Valid Requirements

Procedures, specifications, plans or policies which meet the needs of the customer(s) and are current, realistic, understandable, measurable, achievable and compatible with other requirements. When conformed to, valid requirements yield quality.

Value Added

Activities or work essential to ensure a product or service meets the needs of the customer.

Value engineering

a total approach to design that achieves improved performance and quality by stressing simplicity and integration of design and manufacturing techniques.


Principles or qualities which are worthwhile and govern the operation of total quality management.


a Value-Added Reseller.


A factor that can be altered, measured, or controlled.

Variable data

Numerical information that can be changed during application operation. It includes timer and counter accumulated values, thumbwheel settings, and arithmetic results.


Periodic or sporadic changes or deviations within a process.


A two-electrode semiconductor device with a voltage-dependant non-linear resistance that drops markedly as the applied voltage is increased. It is used to suppress transient voltage surges.


Visual basic for applications


Video Display Terminal.


A quantity that denotes both magnitude and direction. Vectors are commonly represented by a line segment with an arrow; the length represents the magnitude; the orientation in space and the placement of the arrow at one end of the line represents the direction.

Vector quantity

A quantity that denotes both magnitude and direction in relation to a given frame of reference. Examples of quantities that are vectors are displacement, velocity, force, and magnetic intensity.


A vector quantity that denotes both magnitude (e.g., speed) and direction in relation to a given frame of reference.

Velocity loop

A feedback control loop in which the controlled parameter is motor velocity. Usually uses a tachometer for a feedback device.


Variable-Frequency Drive.


Video Graphics Adapter. A video adapter introduced in 1987. The VGA duplicates all video modes of the EGA (Enhanced Graphics Adapter) and provides several additional modes.

VRC Vertical redundancy check. An error-checking method that adds a check or parity bit to each character in a message so the number of 1 bits, including the parity bit, in each character is odd (odd parity) or even (even parity).



The logical or conceptual view of something, which implies some sort of mapping function to get from conceptual to physical.

Vision systems

employ video cameras for inspection, verification, measurement, code reading and other purposes. Vision systems employ sophisticated pattern-recognition software to analyze the images they capture and compare it against defined patterns.

Voice recognition systems

Devices which are either portable and fixed station which use human speech as data input and translate it into machine recognizable codes or commands.

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Wait before transmitting positive ACKnowledgment. In binary synchronous communications, this DLE sequence is sent by a receiving station to indicate that it is temporarily not ready to receive.


Wide-area network

Warehouse management systems

Software that integrates activities performed mechanically and by humans with an information system to effectively manage warehouse business processes and direct warehouse activities.

Watchdog timer

A timer that monitors a cyclical process and is cleared at the conclusion of each cycle. If the watchdog runs past its programmed time period, it will cause a fault.


The distance traveled by light (or other radiation) while completing one complete sine-wave cycle. It is expressed in nanometers (nm). Each color has a specific wavelength.

Weighted value

The numerical value assigned to any single bit as a function of its position in a word.


A temporary, usually rectangular, bounded area on a CRT display that includes particular entities for entry, modification, or deletion.


A trough, with hinged or removable covers; for housing and protecting electric wires and cables and in which conductors are laid in place after the wireway has been installed as a complete system. A wireway may be made of either sheet metal or of a flame-retardant nonmetallic material.


A grouping or a number of bits in a sequence that is treated as a unit.

Word length

The number of bits in a word. In a programmable controller, unless stated otherwise, a word has 16 data bits.


The magnitude of a force times the distance through which that force is applied. (work = force x distance)

Work area

A portion of the data table reserved for specific processor functions.


1) A powerful stand-alone computer of the sort used in applications requiring considerable calculating or graphics capability.
2) A combination of input, output, and computing hardware that can be used for work by an individual.
3) A microcomputer or terminal connected to a network.

Wrap around

In a display, when data is moved in one direction through the display, or a cursor is moved though the data, as the data displayed or the cursor position reaches one extreme end, it jumps to the other extreme end so that the movement can continue.


To load data into somewhere (memory, an output, another station).

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The axis of motion that is always horizontal and parallel to the work holding surface.

x-y matrix

A group of rows and columns. The x-axis is the horizontal row, and the y-axis is the vertical column. An x-y matrix is the reference framework for two-dimensional structures, such as mathematical tables, display screens, digitizer tablets, dot matrix printers and 2-D graphics images.

x-y-z matrix

A three-dimensional structure. The x and y axes represent the first two dimensions; the z axis, the third dimension. In a graphic image, the x and y denote width and height; the z denotes depth.


Extensible markup


Transmitter. A device that sends data.


An asynchronous communication protocol for the receiving station to control the flow of data from the transmitting station. When the receiving station cannot continue to receive any more data, as when its buffer is full, it transmits an XOFF (DC3) control character that tells the sender to stop. When the receiving station is again able to process more data, it transmits an XON (DC1) control character that tells the sender to resume transmission. This protocol is also referred to as software handshaking.

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See x-y matrix.


Angular rotation about the vertical axis, typically the Z-axis for X-Y-Z.

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The third dimension in a graphics image. The width is the x-axis and the height is the y-axis.

ZCL instruction

Zone-control last-state instruction. A user-programmed fence for ZCL zones.

ZCL zones

Assigned program areas that may control the same outputs through separate rungs, at different times. Each ZCL zone is bound and controlled by ZCL instructions. If all ZCL zones are disabled, the outputs in the zones would remain in their most recent controlled state.

Zener diode

A diode that, above a certain reverse voltage (the zener value), has a sudden rise in current. The voltage across the diode remains essentially constant for any further increase in reverse current, up to the allowable dissipation rating.

Zero Adjustments

Used when 'setting up' a transducer to adjust the output signal to zero when zero load/pressure is applied.

Zero Balance

The output signal of the transducer with rated excitation and with no-load applied, usually expressed as a percent of rated output.

Zero Offset

1) The difference expressed in degrees between true zero and an indication given by a measuring instrument.
2) See Zero Suppression

Zero Point

The electrical zero point where zero millivolts would be displayed. Used in conjunction with the slope control to provide a narrower range calibration.

Zero Power Resistance

The resistance of a thermistor or RTD element with no power being dissipated.

Zero Return

The difference in zero balance measured immediately before rated load application of specified duration and measured after removal of the load, and when the output has stabilized.

Zero Suppression

The span of an indicator or chart recorder may be offset from zero (zero suppressed) such that neither limit of the span will be zero. For example, a temperature recorder which records a 100? span from 400? to 500? is said to have 400? zero suppression.

Zero Voltage Switching

The making or breaking of circuit timed such that the transition occurs when the voltage wave form crosses zero voltage; typically only found in solid state switching devices.

ZIF connector

Zero-REPLACEion-Force connector. A connector for which male and female contacts do not initially touch each other while the connector halves are being engaged. Instead, the halves are physically positioned together, and then a turn of an actuating cam arrangement mates all the contacts at once.