1 a logic positive, high, or 1.

A/D Analog to digital converter (see ADC).

abort the disruption of normal operation.

absolute pressure a pressure measured relative to zero pressure.

absorptive law a special case of Boolean algebra where A(A+B) becomes A.

absorption loss
when sound or vibration energy is lost in a transmitting or reflecting medium. This is the result of generation of other forms of energy such as heat.

AC (Alternating Current)
most commonly an electrical current and voltage that changes in a sinusoidal pattern as a function of time. It is also used for voltages and currents that are not steady (DC). Electrical power is normally distributed at 60Hz or 50Hz.

AC contactor
a contactor designed for AC power.

acceptance test
a test for evaluating a newly purchased system’s performance, capabilities, and conformity to specifications, before accepting, and paying the supplier.

accumulator
a temporary data register in a computer CPU.

accuracy
the difference between an ideal value and a physically realizable value.

acidity
a solution that has an excessive number of hydrogen atoms. Acids are normally corrosive.

acknowledgement (ACK)
a response that indicates that data has been transmitted correctly.

acoustic
another term for sound.

actuator
a device that when activated will result in a mechanical motion. For example a motor, a solenoid valve, etc.

ADC (Analog to Digital Converter)
a circuit that will convert an analog voltage to a digital value, also referred to as A/D.

ADCCP (Advanced Data Communications Procedure)
ANSI standard for synchronous communication links with primary and secondary functions.

address
a code (often a number) that specifies a location in a computers memory.

address register
a pointer to memory locations.

adsorption
the ability of a material or apparatus to adsorb energy.

agitator
causes fluids or gases to mix.

AI (Artificial Intelligence)
the use of computer software to mimic some of the cognitive human processes.

algorithms
a software procedure to solve a particular problem.

aliasing
in digital systems there are natural limits to resolution and time that can be exceeded, thus aliasing the data. For example. an event may happen too fast to be noticed, or a point may be too small to be displayed on a monitor.

alkaline
a solution that has an excess of HO pairs will be a base. This is the compliment to an acid.

alpha rays
ions that are emitted as the result of atomic fission or fusion.

alphanumeric
a sequence of characters that contains both numbers and letters.

ALU (Arithmetic Logic Unit)
a part of a computer that is dedicated to mathematical operations.

AM (Amplitude Modulation)
a fixed frequency carrier signal that is changed in amplitude to encode a change in a signal.

ambient
normal or current environmental conditions.

ambient noise
a sort of background noise that is difficult to isolate, and tends to be present throughout the volume of interest.

ambient temperature
the normal temperature of the design environment.

analog signal
a signal that has continuous values, typically voltage.

analysis
the process of review to measure some quality.

and
a Boolean operation that requires all arguments to be true before the result is true.

annealing
heating of metal to relieve internal stresses. In many cases this may soften the material.

annotation
a special note added to a design for explanatory purposes.

ANSI (American National Standards Institute)
a developer of standards, and a member of ISO.

APF (All Plastic Fiber cable)
fiber optic cable that is made of plastic, instead of glass.

API (Application Program Interface)
a set of functions, and procedures that describes how a program will use another service/library/program/etc.

application
the task which a tool is put to, This normally suggests some level of user or real world interaction.

application layer
the top layer in the OSI model that includes programs the user would run, such as a mail reader.

APT (Automatically Programmed Tools)
a language used for directing computer controlled machine tools.

arc
when the electric field strength exceeds the dielectric breakdown voltage, electrons will flow.

architecture
the general layout or design at a higher level.

armature
the central rotating portion of a DC motor or generator, or a moving part of a relay.

ARPA (Advanced Research Projects Agency)
now DARPA. Originally funded ARPANET.

ASCII (American Standard Code for Information Interchange)
a set of numerical codes that correspond to numbers, letters, special characters, and control codes.

aspirator
a device that moves materials with suction.

assembler
converts assembly language into machine code.

assembly language
a mnemonic set of commands that can be directly converted into commands for a CPU.

associative dimensioning
a method for linking dimension elements to elements in a drawing.

associative laws
Boolean algebra laws A+(B+C) = (A+B)+C or A(BC) = (AB)C

asynchronous
events that happen on an irregular basis, and are not predictable.

asynchronous communications (serial)
strings of characters (often ASCII) are broken down into a series of on/off bits. These are framed with start/stop bits, and parity checks for error detection, and then send out one character at a time. The use of start bits allows the characters to be sent out at irregular times.

attenuation
to decrease the magnitude of a signal.

attenuation
as the sound/vibration energy propagates, it will undergo losses. The losses are known as attenuation, and are often measured in dB. For general specifications, the attenuation may be tied to units of dB/ft.

attribute
a nongraphical feature of a part, such as color.

audible range
the range of frequencies that the human ear can normally detect from 16 to 20,000 Hz.

automated
a process that operates without human intervention.

automatic control
a feedback of a system state is compared to a desired value and the control value for the system is adjusted by electronics, mechanics and/or computer to compensate for differences.

auxiliary power
secondary power supplies for remote or isolated systems.

AWG (American Wire Gauge)
specifies conductor size. As the number gets larger, the conductors get smaller.

background
in multitasking systems, processes may be running in the background while the user is working in the foreground, giving the user the impression that they are the only user of the machine (except when the background job is computationally intensive).

background suppression
the ability of a sensing system to discriminate between the signal of interest, and background noise or signals.

backplane
a circuit board located at the back of a circuit board cabinet. The backplane has connectors that boards are plugged into as they are added.

backup
a redundant system to replace a system that has failed.

backward chaining
an expert system looks at the results and looks at the rules to see logically how to get there.

band pressure Level
when measuring the spectrum of a sound, it is generally done by looking at frequencies in a certain bandwidth. This bandwidth will have a certain pressure value that is an aggregate for whatever frequencies are in the bandwidth.

base
1. a substance that will have an excess of HO ions in solution form. This will react with an acid. 2. the base numbering system used. For example base 10 is decimal, base 2 is binary

baseband
a network strategy in which there is a single carrier frequency, that all connected machines must watch continually, and participate in each transaction.

BASIC
(Beginner’s All Purpose Symbolic Instruction Code)

batch processing
an outdated method involving running only one program on a computer at once, sequentially. The only practical use is for very intensive jobs on a supercomputer.

battery backup
a battery based power supply that keeps a computer (or only memory) on when the master power is off.

BAUD
The maximum number of bits that may be transmitted through a serial line in one second. This also includes some overhead bits.

BCC (Block Check Character)
a character that can check the validity of the data in a block.

BCD (Binary Coded Decimal)
numerical digits (0 to 9) are encoded using 4 bits. This allows two numerical digits to each byte.

beam
a wave of energy waves such as light or sound. A beam implies that it is not radiating in all directions, and covers an arc or cone of a few degrees.

bearing
a mechanical support between two moving surfaces. Common types are ball bearings (light weight) and roller bearings (heavy weight), journal bearings (rotating shafts).

beats
if two different sound frequencies are mixed, they will generate other frequencies. if a 1000Hz and 1001Hz sound are heard, a 1Hz (=1000

benchmark
a figure to compare with. If talking about computers, these are often some numbers that can be use to do relative rankings of speeds, etc. If talking about design, we can benchmark our products against our competitors to determine our weaknesses.

Bernoulli’s principle
a higher fluid flow rate will result in a lower pressure.

beta ratio
a ratio of pipe diameter to orifice diameter.

beta rays
electrons are emitted from a fission or fusion reaction.

beta site
a software tester who is actually using the software for practical applications, while looking for bugs. After this stage, software will be released commercially.

big
endian

binary
a base 2 numbering system with the digits 0 and 1.

binary
specifies a number system that has 2 digits, or two states.

binary number
a collection of binary values that allows numbers to be constructed. A binary number is base 2, whereas normal numbering systems are base 10.

BIOS (Basic Input Output System)
a set of basic system calls for accessing hardware, or software services in a computer. This is typically a level lower than the operating system.

bit
a single binary digit. Typically the symbols 0 and 1 are used to represent the bit value.

bit/nibble/byte/word
binary numbers use a 2 value number system (as opposed to the decimal 0

BITNET (Because It’s Time NET)
An academic network that has been merged with CSNET.

blackboard
a computer architecture when different computers share a common memory area (each has its own private area) for sharing/passing information.

blast furnace
a furnace that generates high temperatures by blowing air into the combustion.

bleed nozzle
a valve or nozzle for releasing pressure from a system.

block
a group of bytes or words.

block diagram
a symbolic diagram that illustrates a system layout and connection. This can be used for analysis, planning and/or programming.

block diagrams
a special diagram for illustrating a control system design.

BOC (Bell Operating Company)
there are a total of 7 regional telephone companies in the U.S.A.

boiler
a device that will boil water into steam by burning fuel.

BOM (Bills Of Materials)
list of materials needed in the production of parts, assemblies, etc.

Boolean
a system of numbers based on logic, instead of real numbers. There are many similarities to normal mathematics and algebra, but a separate set of operators, axioms, etc. are used.

bottom
up design

bounce
switch contacts may not make absolute contact when switching. They make and break contact a few times as they are coming into contact.

Bourdon tube
a pressure tube that converts pressure to displacement.

BPS (Bits Per Second)
the total number of bits that can be passed between a sender and listener in one second. This is also known as the BAUD rate.

branch
a command in a program that can cause it to start running elsewhere.

bread board
a term used to describe a temporary electronic mounting board. This is used to prototype a circuit before doing final construction. The main purpose is to verify the basic design.

breadth first search
an AI search technique that examines all possible decisions before making the next move.

breakaway torque
the start

breakdown torque
the maximum torque that an AC motor can produce at the rated voltage and frequency.

bridge
1. an arrangement of (typically 4) balanced resistors used for measurement. 2. A network device that connects two different networks, and sorts out packets to pass across.

broad
band noise

broadband networks
multiple frequencies are used with multiplexing to increase the transmission rates in networks.

broadcast
a network term that describes a general broadcast that should be delivered to all clients on a network. For example this is how Ethernet sends all of its packets.

brush
a sliding electrical conductor that conducts power to/from a rotor.

BSC (Binary Synchronous Communication)
a byte oriented synchronous communication protocol developed by IBM.

BSD (Berkeley Software Distribution)
one of the major versions of UNIX.

buffer
a temporary area in which data is stored on its way from one place to another. Used for communication bottlenecks and asynchronous connections.

bugs
hardware or software problems that prevent desired components operation.

burner
a term often used for a device that programs EPROMs, PALs, etc. or a bad cook.

bus
a computer has buses (collections of conductors) to move data, addresses, and control signals between components. For example to get a memory value, the address value provided the binary memory address, the control bus instructs all the devices to read/write, and to examine the address. If the address is valid for one part of the computer, it will put a value on the data bus that the CPU can then read.

byte
an 8 bit binary number. The most common unit for modern computers.

CAA (Computer Aided Analysis)
allows the user to input the definition of a part and calculate the performance variables.

cable
a communication wire with electrical and mechanical shielding for harsh environments.

CAD (Computer Aided Design)
is the creation and optimization of the design itself using the computer as a productivity tool. Components of CAD include computer graphics, a user interface, and geometric modeling.

CAD (Computer Aided Drafting)
is one component of CAD which allows the user to input engineering drawings on the computer screen and print them out to a plotter or other device.

CADD (Computer Aided Design Drafting)
the earliest forms of CAD systems were simple electronic versions of manual drafting, and thus are called CADD.

CAE (Computer Aided Engineering)
the use of computers to assist in engineering. One example is the use of Finite Element Analysis (FEA) to verify the strength of a design.

CAM (Computer Aided Manufacturing)
a family of methods that involves computer supported manufacturing on the factory floor.

capacitance
referring to the ability of a device to store energy. This is used for electrical capacitors, thermal masses, gas cylinders, etc.

capacitor
a device for storing energy or mass.

capacity
the ability to absorb something else.

carrier
a high/low frequency signal that is used to transmit another signal.

carry flag
an indication when a mathematical operator has gone past the limitations of the hardware/software.

cascade
a method for connecting devices to increase their range, or connecting things so that they operate in sequence. This is also called chaining.

cassette
a holder for audio and data tapes.

Celsius
a temperature scale the uses 0 as the freezing point of water and 100 as the boiling point.

centrifugal force
the force on an orbiting object the would cause it to accelerate outwards.

centripetal force
the force that must be applied to an orbiting object so that it will not fly outwards.

channel
an independent signal pathway.

character
a single byte, that when displayed is some recognizable form, such as a letter in the alphabet, or a punctuation mark.

checksum
when many bytes of data are transmitted, a checksum can be used to check the validity of the data. It is commonly the numerical sum of all of the bytes transmitted.

chip
a loose term for an integrated circuit.

chromatography
gases or liquids can be analyzed by how far their constituent parts can migrate through a porous material.

CIM (Computer Integrated Manufacturing)
computers can be used at a higher level to track and guide products as they move through the facility. CIM may or may not include CAD/CAM.

CL (Cutter Location)
an APT program is converted into a set of x

clear
a signal or operation to reset data and status values.

client
server

clipping
the automatic cutting of lines that project outside the viewing area on a computer screen.

clock
a signal from a digital oscillator. This is used to make all of the devices in a digital system work synchronously.

clock speed
the rate at which a computers main time clock works at. The CPU instruction speed is usually some multiple or fraction of this number, but true program execution speeds are loosely related at best.

closed loop
a system that measures system performance and trims the operation. This is also known as feedback. If there is no feedback the system is called open loop.

CMOS (Complimentary Metal Oxide Semi
conductor)

CNC (Computer Numerical Control)
machine tools are equipped with a control computer, and will perform a task. The most popular is milling.

coalescing
a process for filtering liquids suspended in air. The liquid condenses on glass fibers.

coax
see coaxial cable.

coaxial cable
a central wire contains a signal conductor, and an outer shield provides noise immunity. This configuration is limited by its coaxial geometry, but it provides very high noise immunity.

cogging
a machine steps through motions in a jerking manner. The result may be low frequency vibration.

coil
wire wound into a coil (tightly packed helix) used to create electromagnetic attraction. Used in relays, motors, solenoids, etc. These are also used alone as inductors.

collisions
when more than one network client tries to send a packet at any one time, they will collide. Both of the packets will be corrupted, and as a result special algorithms and hardware are used to abort the write, wait for a random time, and retry the transmission. Collisions are a good measure of network overuse.

colorimetry
a method for identifying chemicals using their colors.

combustion
a burning process generating heat and light when certain chemicals are added.

command
a computer term for a function that has an immediate effect, such as listing the files in a directory.

communication
the transfer of data between computing systems.

commutative laws
Booleans algebra laws A+B = B+A and AB=BA.

compare
a computer program element that examines one or more variables, determines equality/inequality, and then performs some action, sometimes a branch.

compatibility
a measure of the similarity of a design to a standard. This is often expressed as a percentage for software. Anything less than 100% is not desirable.

compiler
a tool to change a high level language such as C into assembler.

compliment
to take the logical negative. TRUE becomes false and vice versa.

component
an interchangeable part of a larger system. Components can be used to cut down manufacturing and maintenance difficulties.

compressor
a device that will decrease the volume of a gas

computer
a device constructed about a central instruction processor. In general the computer can be reconfigured (software/firmware/hardware) to perform alternate tasks.

Computer Graphics
is the use of the computer to draw pictures using an input device to specify geometry and other attributes and an output device to display a picture. It allows engineers to communicate with the computer through geometry.

concentric
a shared center between two or more objects.

concurrent
two or more activities occur at the same time, but are not necessarily the same.

concurrent engineering
all phases of the products life are considered during design, and not later during design review stages.

condenser
a system component that will convert steam to water. Typically used in power generators.

conduction
the transfer of energy through some medium.

configuration
a numbers of multifunction components can be connected in a variety of configurations.

connection
a network term for communication that involves first establishing a connection, second data transmission, and third closing the connection. Connectionless networking does not require connection.

constant
a number with a value that should not vary.

constraints
are performance variables with limits. Constraints are used to specify when a design is feasible. If constraints are not met, the design is not feasible.

contact
1. metal pieces that when touched will allow current to pass, when separated will stop the flow of current. 2. in PLCs contacts are two vertical lines that represent an input, or internal memory location.

contactor
a high current relay.

continuous Noise
a noise that is ongoing, and present. This differentiates from instantaneous, or intermittent noise sources.

continuous Spectrum
a noise has a set of components that are evenly distributed on a spectral graph.

control relay
a relay that does not control any external devices directly. It is used like a variable in a high level programming language.

control variable
a system parameter that we can set to change the system operation.

controls
a system that is attached to a process. Its purpose is to direct the process to some set value.

convection
the transfer of heat energy to liquid or gas that is moving past the surface of an object.

core memory
an outdated term describing memory made using small torii that could be polarized magnetically to store data bits. The term lives on when describing some concepts, for example a ‚”core dump’ in UNIX. Believe it or not this has not been used for decades but still appears in many new textbooks.

coriolis force
a force that tends to cause spinning in moving frames of reference. Consider the direction of the water swirl down a drain pipe, it changes from the north to the south of the earth.

correction factor
a formal version of the ‚”fudge factor ‘. Typically a value used to multiply or add another value to account for hard to quantify values. This is the friend of the factor of safety.

counter
a system to count events. This can be either software or hardware.

cps (characters per second)
This can be a good measure of printing or data transmission speed, but it is not commonly used.

CPU (Central Processing Unit)
the main computer element that examines machine code instructions and executes results.

CRC (Cyclic Redundancy Check)
used to check transmitted blocks of data for validity.

criteria
are performance variables used to measure the quality of a design. Criteria are usually defined in terms of degree

crosstalk
signals in one conductor induce signals in other conductors, possibly creating false signals.

CRT (Cathode Ray Tubes)
are the display device of choice today. A CRT consists of a phosphor

crucible
1. a vessel for holding high temperature materials 2.

CSA (Canadian Standards Association)
an association that develops standards and does some product testing.

CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
a protocol that causes computers to use the same communication line by waiting for turns. This is used in networks such as Ethernet.

CSNET (Computer+Science NETwork)
a large network that was merged with BITNET.

CTS (Clear To Send)
used to prevent collisions in asynchronous serial communications.

current loop
communications that use a full electronic loop to reduce the effects of induced noise. RS

current rating
this is typically the maximum current that a designer should expect from a system, or the maximum current that an input will draw. Although some devices will continue to work outside rated values, not all will, and thus this limit should be observed in a robust system. Note: exceeding these limits is unsafe, and should be done only under proper engineering conditions.

current sink
a device that allow current to flow through to ground when activated.

current source
a device that provides current from another source when activated.

cursors
are movable trackers on a computer screen which indicate the currently addressed screen position, or the focus of user input. The cursor is usually represented by an arrow, a flashing character or cross

customer requirements
the qualitative and quantitative minimums and maximums specified by a customer. These drive the product design process.

cycle
one period of a periodic function.

cylinder
a piston will be driven in a cylinder for a variety of purposes. The cylinder guides the piston, and provides a seal between the front and rear of the piston.

DARPA (Defense Advanced Research Projects Agency)

data acquisition
refers to the automated collection of information collected from a process or system.

data highway
a term for a communication bus between two separated computers, or peripherals. This term is mainly used for PLC’s.

data link layer
an OSI model layer

data logger
a dedicated system for data acquisition.

data register
stores data values temporarily in a CPU.

database
a software program that stores and recalls data in an organized way.

DC (Direct Current)
a current that flows only in one direction. The alternative is AC.

DCA (Defense Communications Agency)
developed DDN.

DCD (Data Carrier Detect)
used as a handshake in asynchronous communication.

DCE (Data Communications Equipment)
A term used when describing unintelligent serial communications clients. An example of this equipment is a modem. The complement to this is DTE.

DCE (Distributed Computing Environment)
applications can be distributed over a number of computers because of the use of standards interfaces, functions, and procedures.

DDN (Defense Data Network)
a group of DoD networks, including MILNET.

dead band
a region for a device when it no longer operates.

dead time
a delay between an event occurring and the resulting action.

debounce
a switch may not make sudden and complete contact as it is closes, circuitry can be added to

debug
after a program has been written it undergoes a testing stage called debugging that involves trying to locate and eliminate logic and other errors.

decision support
the use of on

DECnet (Digital Equipment Corporation net)
a proprietary network architecture developed by DEC. decrement

dedicated computer
a computer with only one task.

default
a standard condition.

demorgan’s laws
Boolean laws great for simplifying equations ~(AB) = ~A + ~B, or ~(A+B) = ~A~B.

density
a mass per unit volume.

depth first search
an artificial intelligence technique that follows a single line of reasoning first.

derivative control
a control technique that uses changes in the system of setpoint to drive the system. This control approach gives fast response to change.

design
creation of a new part/product based on perceived needs. Design implies a few steps that are ill defined, but generally include, rough conceptual design, detailed design, analysis, redesign, and testing.

design capture
the process of formally describing a design, either through drafted drawings, schematic drawings, etc.

design cycle
the steps of the design. The use of the word cycle implies that it never ends, although we must at some point decide to release a design.

design Variables
are the parameters in the design that describe the part. Design variables usually include geometric dimensions, material type, tolerances, and engineering notes.

detector
a device to determine when a certain condition has been met.

device driver
controls a hardware device with a piece of modular software.

DFA (Design For Assembly)
a method that guides product design/redesign to ease assembly times and difficulties.

DFT (Design for Testability)
a set of design axioms that generally calls for the reduction of test steps, with the greatest coverage for failure modes in each test step.

diagnostic
a system or set of procedures that may be followed to identify where systems may have failed. These are most often done for mission critical systems, or industrial machines where the user may not have the technical capability to evaluate the system.

diaphragm
used to separate two materials, while allowing pressure to be transmitted.

differential
refers to a relative difference between two values. Also used to describe a calculus derivative operator.

differential amplifier
an amplifier that will subtract two or more input voltages.

diffuse field
multiple reflections result in a uniform and high sound pressure level.

digital
a system based on binary on

diode
a semiconductor device that will allow current to flow in one direction.

DIP switches
small banks of switches designed to have the same footprint as an integrated circuit.

distributed
suggests that computer programs are split into parts or functions and run on different computers

distributed system
a system can be split into parts. Typical components split are mechanical, computer, sensors, software, etc.

DLE (Data Link Escape)
An RS

DMA (Direct Memory Access)
used as a method of transferring memory in and out of a computer without slowing down the CPU.

DNS (Domain Name System)
an internet method for name and address tracking.

documentation
one or more documents that instruct in the use, installation, setup, maintenance, troubleshooting, etc. for software or machinery. A poor design supported by good documentation can often be more useful than a good design unsupported by poor documentation.

domain
the basic name for a small or large network.

doppler shift
as objects move relative to each other, a frequency generated by one will be perceived at another frequency by the other.

DOS (Disk Operating System)
the portion of an operating system that handles basic I/O operations. The most common example is Microsoft MS

dotted decimal notation
the method for addressing computers on the internet with IP numbers such as ‚Äò129.100.100.13′.

double pole
a double pole switch will allow connection between two contacts. These are useful when making motor reversers. see also single pole.

double precision
a real number is represented with 8 bytes (single precision is 4) to give more precision for calculations.

double throw
a switch or relay that has two sets of contacts.

download
to retrieve a program from a server or higher level computer.

downtime
a system is removed from production for a given amount of downtime.

drag
a force that is the result of a motion of an object in a viscous fluid.

drop
a term describing a short connection to peripheral I/O.

drum sequencer
a drum has raised/lowered sections and as it rotates it opens/closes contacts and will give sequential operation.

dry contact
an isolated output, often a relay switched output.

DSP (Digital Signal Processor)
a medium complexity micro-controller that has a build in floating point unit. These are very common in devices such as modems.

DSR (Data Set Ready)
used as a data handshake in asynchronous communications.

DTE (Data Terminal Equipment)
a serial communication line used in RS

DTR (Data Terminal Ready)
used as a data handshake in asynchronous communications to indicate a listener is ready to receive data.

dump
a large block of memory is moved at once (as a sort of system snapshot).

duplex
serial communication that is in both directions between computers at the same time.

dynamic braking
a motor is used as a brake by connecting the windings to resistors. In effect the motor becomes a generator, and the resistors dissipate the energy as heat.

dynamic variable
a variable with a value that is constantly changing.

dyne
a unit of force

echo
a reflected sound wave.

eddy currents
small currents that circulate in metals as currents flow in nearby conductors. Generally unwanted.

EEPROM
Electrically Erasable Programmable Read Only Memory.These chips can be erased and programmed while in use with a computer, and store memory that is not sensitive to power.

effective sound pressure
the RMS pressure value gives the effective sound value for fluctuating pressure values. This value is some fraction of the peak pressure value.

EIA (Electronic Industries Association)
A common industry standards group focusing on electrical standards.

electro
optic isolator

electromagnetic
a broad range term refering to magnetic waves. This goes from low frequency signals such as AM radio, up to very high frequency waves such as light and X

electrostatic
devices that used trapped charge to apply forces and caused distribution. An example is droplets of paint that have been electrically charged can be caused to disperse evenly over a surface that is oppositely charged.

electrostatics discharge
a sudden release of static electric charge (in non-grounded systems). This can lead to uncomfortable electrical shocks, or destruction of circuitry.

EMI (ElectroMagnetic Interference)
transient magnetic fields cause noise in other systems.

emulsify
to mix two materials that would not normally mix. for example an emulsifier can cause oil and water to mix.

enable
a digital signal that allows a device to work.

encoding
a conversion between different data forms.

energize
to apply power to a circuit or component.

energy
the result of work. This concept underlies all of engineering. Energy is shaped, directed and focused to perform tasks.

engineering work stations
are self contained computer graphics systems with a local CPU which can be networked to larger computers if necessary. The engineering work station is capable of performing engineering synthesis, analysis, and optimization operations locally.

EOH (End of Header)
A code in a message header that marks the end of the header block.

EOT (End Of Transmission)
an ASCII code to indicate the end of a communications.

EPROM (ELECTRICALLY Programmable Read Only Memory)
A program can be written to this memory using a special programmer, and erased with ultraviolet light. After a program is written, it does not require power for storage.

error signal
a control signal that is the difference between a desired and actual position.

ESD
see electrostatic discharge.

esters
a chemical that was formed by a reaction between alcohol and an acid.

ETX (End Of Text)
a marker to indicate the end of a text block in data transmission.

even parity
a checksum bit used to verify data in other bits of a byte.

execution
when a computer is under the control of a program, the program is said to be executing.

expansion principle
when heat is applied a liquid will expand.

fail safe
a design concept where system failure will bring the system to an idle or safe state.

Faraday’s electromagnetic induction law
if a conductor moves through a magnetic field a current will be induced. The angle between the motion and the magnetic field needs to be 90 deg for maximum current.

Fahrenheit
a temperature system that has 180 degrees between the freezing and boiling point of water.

fatal error
an error so significant that a software/hardware cannot continue to operate in a reliable manner.

fault
a small error that may be recoverable, or may result in a fatal error.

FCS (Frame Check Sequence)
data check flag for communications.

FDDI (Fiber Distributed Data Interface)
a fiber optic token ring network scheme in which the control tokens are counter rotating.

FDX (Full Duplex)
all characters that are transmitted are reflected back to the sender.

FEA (Finite Element Analysis)
is a numerical technique in which the analysis of a complex part is subdivided into the analysis of small simple subdivisions.

feedback
a common engineering term for a system that examines the output of a system and uses is to tune the system. Common forms are negative feedback to make systems stable, and positive feedback to make systems unstable.

fetch
when the CPU gets a data value from memory.

fiber optics
data can be transmitted by switching light on/off, and transmitting the signal through an optical fiber. This is becoming the method of choice for most long distance data lines because of the low losses and immunity to EMI.

FIFO (First In First Out)
items are pushed on a stack. The items can then be pulled back off last first.

file
a concept of a serial sequence of bytes that the computer can store information in, normally on the disk. This is a ubiquitous concept, but file is also used by Allen Bradley to describe an array of data.

filter
a device that will selectively pass matter or energy.

firmware
software stored on ROM (or equivalent).

flag
a single binary bit that indicates that an event has/has not happened.

flag
a single bit variable that is true or not. The concept is that if a flag is set, then some event has happened, or completed, and the flag should trigger some other event.

flame
an email, or net news item that is overtly critical of another user, or an opinion. These are common because of the ad

flange
a thick junction for joining two pipes.

floating point
uses integer math to represent real numbers.

flow chart
a schematic diagram for representing program flow. This can be used during design of software, or afterwards to explain its operation.

flow meter
a device for measuring the flow rate of fluid.

flow rate
the volume of fluid moving through an area in a fixed unit of time.

fluorescence
incoming UV light or X

force
a PLC output or input value can be set on artificially to test programs or hardware. This method is not suggested.

format
1. a physical and/or data structure that makes data re-readable, 2. the process of putting a structure on a disk or other media.

forward chaining
an expert system approach to examine a set of facts and reason about the probable outcome.

fragmentation
the splitting of an network data packet into smaller fragments to ease transmission.

frame buffers
store the raster image in memory locations for each pixel. The number of colors or shades of gray for each pixel is determined by the number of bits of information for each pixel in the frame buffer.

free field
a sound field where none of the sound energy is reflected.

frequency
the number of cycles per second for a sinusoidally oscillating vibration/sound.

friction
the force resulting from the mechanical contact between two masses.

FSK (Frequency Shift Keying)
uses two different frequencies, shifting back and forth to transmit bits serially.

FTP (File Transfer Protocol)
a popular internet protocol for moving files between computers.

fudge factor
a number that is used to multiply or add to other values to make the experimental and theoretical values agree.

full duplex
a two way serial communication channel can carry information both ways, and each character that is sent is reflected back to the sender for verification.

fuse
a device that will destruct when excessive current flows. It is used to protect the electrical device, humans, and other devices when abnormally high currents are drawn. Note: fuses are essential devices and should never be bypassed, or replaced with fuses having higher current rating.

gamma rays
high energy electromagnetic waves resulting from atomic fission or fusion.

gate
1. a circuit that performs on of the Boolean algebra function (i.e., and, or, not, etc.) 2. a connection between a runner and a part, this can be seen on most injection molded parts as a small bump where the material entered the main mold cavity.

gateway
translates and routes packets between dissimilar networks.

Geiger
Mueller tube

global optimum
the absolute best solution to a problem. When found mathematically, the maximum or minimum cost/utility has been obtained.

gpm (gallons per minute)
a flow rate.

grafcet
a method for programming PLCs that is based on Petri nets. This is now known as SFCs and is part of the IEC 1131

gray code
a modified binary code used for noisy environments. It is devised to only have one bit change at any time. Errors then become extremely obvious when counting up or down.

ground
a buried conductor that acts to pull system neutral voltage values to a safe and common level. All electrical equipment should be connected to ground for safety purposes.

GUI (Graphical User Interface)
the user interacts with a program through a graphical display, often using a mouse.

half cell
a probe that will generate a voltage proportional to the hydrogen content in a solution.

half duplex
see HDX

handshake
electrical lines used to establish and control communications.

hard copy
a paper based printout.

hardware
a mechanical or electrical system. The ‘functionality’ is ‚’frozen’ in hardware, and often difficult to change.

HDLC (High
level Data Link Control)

HDX (Half Duplex)
a two way serial connection between two computer. Unlike FDX, characters that are sent are not reflected back to the sender.

head
pressure in a liquid that is the result of gravity.

hermetic seal
an airtight seal.

hertz
a measure of frequency in cycles per second. The unit is Hz.

hex
see hexadecimal.

hexadecimal
a base 16 number system where the digits are 0 to 9 then A to F, to give a total of 16 digits. This is commonly used when providing numbers to computers.

high
another term used to describe a Boolean true, logical positive, or one.

high level language
a language that uses very powerful commands to increase programming productivity.

horsepower
a unit for measuring power

host
a networked (fully functional) computer.

hot backup
a system on

hydraulic
1. a study of water 2. systems that use fluids to transmit power.

hydrocarbon
a class of molecules that contain carbon and hydrogen. Examples are propane, octane.

hysteresis
a sticking or lagging phenomenon that occurs in many systems. For example, in magnetic systems this is a small amount of magnetic re-polarization in a reversing field, and in friction this is an effect based on coulomb friction that reverses sticking force.

Hz
see hertz

I/O (Input/Output)
a term describing anything that goes into or out of a computer.

IAB (internet Activities Board)
the developer of internet standards.

IC (Integrated Circuit)
a microscopic circuit placed on a thin wafer of semiconductor.

IEC (International Electrical Commission)

IEEE (Institute of Electrical and Electronics Engineers)

IEEE802
a set of standards for LANs and MANs.

IGES (Initial Graphics Exchange Specification)
a standard for moving data between various CAD systems. In particular the format can handle basic geometric entities, such as NURBS, but it is expected to be replaced by PDES/STEP in the near future.

impact instrument
measurements are made based by striking an object. This generally creates an impulse function.

impedance
In electrical systems this is both reactive and real resistance combined. This also applies to power transmission and flows in other types of systems.

impulse Noise
a short duration, high intensity noise. This type of noise is often associated with explosions.

increment
increase a numeric value.

inductance
current flowing through a coil will store energy in a magnetic field.

inductive heating
a metal part is placed inside a coil. A high frequency AC signal is passed through the coil and the resulting magnetic field melts the metal.

inertia
a property where stored energy will keep something in motion unless there is energy added or released.

inference
to make a decision using indirect logic. For example if you are wearing shoes, we can infer that you had to put them on. Deduction is the complementary concept.

inference engine
the part of an expert system that processes rules and facts using forward or backward chaining.

infrared
light that has a frequency below the visible spectrum.

instruction set
a list of all of the commands that available in a programmable system. This could be a list of PLC programming mnemonics, or a list of all of the commands in BASIC.

instrument
a device that will read values from external sensors or probes, and might make control decision.

integral control
a control method that looks at the system error over a long period of time. These controllers are relatively immune to noise and reduce the steady state error, but the do not respond quickly.

integrate
to combine two components with clearly separable functions to obtain a new single component capable of more complex functions.

intelligence
systems will often be able to do simple reasoning or adapt. This can mimic some aspects of human intelligence. These techniques are known as artificial intelligence.

intelligent device
a device that contains some ability to control itself. This reduces the number of tasks that a main computer must perform. This is a form of distributed system.

interface
a connection between a computer and another electrical device, or the real world.

interlock
a device that will inhibit system operation until certain conditions are met. These are often required for safety on industrial equipment to protect workers.

interlock
a flag that ensures that concurrent streams of execution do not conflict, or that they cooperate.

intermittent noise
when sounds change level fluctuate significantly over a measurement time period.

interpreter
programs that are not converted to machine language, but slowly examined one instruction at a time as they are executed.

interrupt
a computer mechanism for temporarily stopping a program, and running another.

inverter
a logic gate that will reverse logic levels from TRUE to/from FALSE.

ion
an atom, molecule or subatomic particle that has a positive or negative charge.

IOR (Inclusive OR)
a normal OR that will be true when any of the inputs are true in any combinations. also see Exclusive OR (EOR).

IP (internet Protocol)
the network layer (OSI model) definitions that allow internet use.

IP datagram
a standard unit of information on the internet.

ISDN (Integrated Services Digital Network)
a combined protocol to carry voice, data and video over 56KB lines.

ISO (International Standards Organization)
a group that develops international standards in a wide variety of areas.

isolation
electrically isolated systems have no direct connection between two halves of the isolating device. Sound isolation uses barriers to physically separate rooms.

isolation transformer
a transformer for isolating AC systems to reduce electrical noise.

jog
a mode where a motor will be advanced while a button is held, but not latched on. It is often used for clearing jams, and loading new material.

jump
a forced branch in a program

jumper
a short wire, or connector to make a permanent setting of hardware parameters.

k, K
specifies magnitudes. 1K = 1024, 1k = 1000 for computers, otherwise 1K = 1k = 1000. Note

Karnaugh maps
a method of graphically simplifying logic.

Kelvin
temperature units that place 0 degrees at absolute zero. The magnitude of one degree is the same as the Celsius scale.

keying
small tabs, prongs, or fillers are used to stop connectors from mating when they are improperly oriented.

KiloBaud, KBaud, KB, Baud
a transmission rate for serial communications (e.g. RS

kinematics/kinetics
is the measure of motion and forces of an object. This analysis is used to measure the performance of objects under load and/or in motion.

label
a name associated with some point in a program to be used by branch instructions.

ladder diagram
a form of circuit diagram normally used for electrical control systems.

ladder logic
a programming language for PLCs that has been developed to look like relay diagrams from the preceding technology of relay based controls.

laminar flow
all of the particles of a fluid or gas are traveling in parallel. The complement to this is turbulent flow.

LAN (Local Area Network)
a network that is typically less than 1km in distance. Transmission rates tend to be high, and costs tend to be low.

latch
an element that can have a certain input or output lock in. In PLCs these can hold an output on after an initial pulse, such as a stop button.

LCD (Liquid Crystal Display)
a fluid between two sheets of light can be polarized to block light. These are commonly used in low power displays, but they require backlighting.

leakage current
a small amount of current that will be present when a device is off.

LED (Light Emitting Diode)
a semiconductor light that is based on a diode.

LIFO (Last In First Out)
similar to FIFO, but the last item pushed onto the stack is the first pulled off.

limit switch
a mechanical switch actuated by motion in a process.

line printer
an old printer style that prints single lines of text. Most people will be familiar with dot matrix style of line printers.

linear
describes a mathematical characteristic of a system where the differential equations are simple linear equations with coefficients.

little
endian

load
In electrical system a load is an output that draws current and consumes power. In mechanical systems it is a mass, or a device that consumes power, such as a turbine.

load cell
a device for measuring large forces.

logic
1. the ability to make decisions based on given values. 2. digital circuitry.

loop
part of a program that is executed repeatedly, or a cable that connects back to itself.

low
a logic negative, or zero.

LRC (Linear Redundancy Check)
a block check character

LSB (Least Significant Bit)
This is the bit with the smallest value in a binary number. for example if the number 10 is converted to binary the result is 1010. The most significant bit is on the left side, with a value of 8, and the least significant bit is on the right with a value of 1

LSD (Least Significant Digit)
This is the least significant digit in a number, found on the right side of a number when written out. For example, in the number $1,234,567 the digit 7 is the least significant.

LSI (Large Scale Integration)
an integrated circuit that contains thousands of elements.

LVDT (Linear Variable Differential Transformer)
a device that can detect linear displacement of a central sliding core in the transformer.

machine language
CPU instructions in numerical form.

macro
a set of commands grouped for convenience.

magnetic field
a field near flowing electrons that will induce other electrons nearby to flow in the opposite direction.

MAN (Metropolitan Area Network)
a network designed for municipal scale connections.

manifold
1. a connectors that splits the flow of fluid or gas. These are used commonly in hydraulic and pneumatic systems. 2. a description for a geometry that does not have any infinitely small points or lines of contact or separation. Most solid modelers deal only with manifold geometry.

mask
one binary word (or byte, etc) is used to block out, or add in digits to another binary number.

mass flow rate
instead of measuring flow in terms of volume per unit of time we use mass per unit time.

mass spectrometer
an instrument that identifies materials and relative proportions at the atomic level. This is done by observing their deflection as passed through a magnetic field.

master/slave
a control scheme where one computer will control one or more slaves. This scheme is used in interfaces such as GPIB, but is increasingly being replaced with peer

mathematical models
of an object or system predict the performance variable values based upon certain input conditions. Mathematical models are used during analysis and optimization procedures.

matrix
an array of numbers

MB MByte, KB, KByte
a unit of memory commonly used for computers. 1 KiloByte = 1 KByte = 1 KB = 1024 bytes. 1 MegaByte = 1 MByte = 1MB = 1024*1024 bytes.

MCR (Master Control Relay)
a relay that will shut down all power to a system.

memory
binary numbers are often stored in memory for fast recall by computers. Inexpensive memory can be purchased in a wide variety of configurations, and is often directly connected to the CPU.

memory
memory stores binary (0,1) patterns that a computer can read or write as program or data. Various types of memories can only be read, some memories lose their contents when power is off. RAM (Random Access Memory)

menu
a multiple choice method of selecting program options.

message
a short sequence of data passed between processes.

microbar
a pressure unit (1 dyne per sq. cm)

microphone
an audio transducer (sensor) used for sound measurements.

microprocessor
the central control chip in a computer. This chip will execute program instructions to direct the computer.

MILNET (MILitary NETwork)
began as part of ARPANET.

MMI (Man Machine Interface)
a user interface terminal.

mnemonic
a few characters that describe an operation. These allow a user to write programs in an intuitive manner, and have them easily converted to CPU instructions.

MODEM (MOdulator/DEModulator)
a device for bidirectional serial communications over phone lines, etc.

module
a part o a larger system that can be interchanged with others.

monitor
an operation mode where the computer can be watched in detail from step to step. This can also refer to a computer screen.

motion detect flow meter
a fluid flow induces measurement.

MRP (Material Requirements Planning)
a method for matching material required by jobs, to the equipment available in the factory.

MSD (Most Significant Digit)
the largest valued digit in a number (eg. 6 is the MSD in 63422). This is often used for binary numbers.

MTBF (Mean Time Between Failure)
the average time (hours usually) between the last repair of a product, and the next expected failure.

MTTR (Mean Time To Repair)
The average time that a device will out of use after failure before it is repaired. This is related to the MTBF.

multicast
a broadcast to some, but not necessarily all, hosts on a network.

multiplexing
a way to efficiently use transmission media by having many signals run through one conductor, or one signal split to run through multiple conductors and rejoined at the receiving end.

multiprocessor
a computer or system that uses more than one computer. Normally this term means a single computer with more than one CPU. This scheme can be used to increase processing speed, or increase reliability.

multivibrator
a digital oscillator producing square or rectangular waveforms.

NAMUR
A European standards organization.

NAND (Not AND)
a Boolean AND operation with the result inverted.

narrowband
uses a small data transmission rate to reduce spectral requirements.

NC
see normally opened/closed

NC (Numerical Control)
a method for controlling machine tools, such as mills, using simple programs.

negative logic
a 0 is a high voltage, and 1 is a low voltage. In Boolean terms it is a duality.

NEMA (National Electrical Manufacturers Association)
this group publishes numerous standards for electrical equipment.

nephelometry
a technique for determining the amount of solids suspended in water using light.

nesting
a term that describes loops

network
a connection of typically more than two computers so that data, email, messages, resources and files may be shared.

NFS (Network File System)
a protocol developed by Sun Microsystems to allow dissimilar computers to share files. The effect is that the various mounted remote disk drives act as a single local disk.

NIC (Network Interface Card)
a computer card that allows a computer to communicate on a network, such as ethernet.

NIST (National Institute of Standards and Technology)
formerly NBS.

NO
see normally open

node
one computer connected to a network.

noise
1. electrical noise is generated mainly by magnetic fields (also electric fields) that induce currents and voltages in other conductors, thereby decreasing the signals present. 2. a sound of high intensity that can be perceived by the human ear.

non
fatal error

non-positive displacement pump
a pump that does not displace a fixed volume of fluid or gas.

non-retentive
when power is lost values will be set back to 0.

NOR (Not OR)
a Boolean function OR that has the results negated.

normally opened/closed
refers to switch types. when in their normal states (not actuated) the normally open (NO) switch will not conduct current. When not actuated the normally closed (NC) switch will conduct current.

NOT
a Boolean function that inverts values. A 1 will become a 0, and a 0 will become a 1.

NOVRAM (NOn Volatile Random Access Memory)
memory that does not lose its contents when turned off.

NPN
a bipolar junction transistor type. When referring to switching, these can be used to sink current to ground.

NPSM
American national standard straight pipe thread for mechanical parts.

NPT
American national standard taper pipe thread.

NSF (National Science Foundation)
a large funder of science projects in USA.

NSFNET (National Science Foundation NETwork)
funded a large network(s) in USA, including a high speed backbone, and connection to a number of super computers.

NTSC (National Television Standards Committee)
a Red

null modem
a cable that connects two RS

OCR (Optical Character Recognition)
Images of text are scanned in, and the computer will try to interpret it, much as a human who is reading a page would. These systems are not perfect, and often rely on spell checkers, and other tricks to achieve reliabilities up to 99%

octal
a base 8 numbering system that uses the digits 0 to 7.

Octave
a doubling of frequency

odd parity
a bit is set during communication to indicate when the data should have an odd number of bits.

OEM (Original Equipment Manufacturer)
a term for a manufacturer that builds equipment for consumers, but uses major components from other manufacturers.

off
line

offset
a value is shifted away or towards some target value.

on
line

one
shot

opcode (operation code)
a single computer instruction. Typically followed by one or more operands.

open
system

open collector
this refers to using transistors for current sourcing or sicking.

open loop
a system that does monitor the result. open loop control systems are common when the process is well behaved.

operand
an operation has an argument (operand) with the mnemonic command.

operating system
software that existing on a computer to allow a user to load/execute/develop their own programs, to interact with peripherals, etc. Good examples of this is UNIX, MS

optimization
occurs after synthesis and after a satisfactory design is created. The design is optimized by iteratively proposing a design and using calculated design criteria to propose a better design.

optoisolators
devices that use a light emitter to control a photoswitch. The effect is that inputs and outputs are electrically separate, but connected. These are of particular interest when an interface between very noisy environments are required.

OR
the Boolean OR function.

orifice
a small hole. Typically this is places in a fluid/gas flow to create a pressure difference and slow the flow. It will increase the flow resistance in the system.

oscillator
a device that produces a sinusoidal output.

oscilloscope
a device that can read and display voltages as a function for time.

OSHA (Occupational safety and Health Act)
these direct what is safe in industrial and commercial operations.

OSI (Open System Interconnect)
an international standards program to promote computer connectivity, regardless of computer type, or manufacturer.

overflow
the result of a mathematical operation passes by the numerical limitations of the hardware logic, or algorithm.

overshoot
the inertia of a controlled system will cause it to pass a target value and then return.

parallel communication
bits are passed in parallel conductors, thus increasing the transmission rates dramatically.

parallel design process
evaluates all aspects of the design simultaneously in each iteration. The design itself is sent to all analysis modules including manufacturability, and engineering analysis modules; redesign decisions are based on all results at once.

parallel programs
theoretically, these computer programs do more than one thing simultaneously.

parity
a parity bit is often added to bytes for error detection purposes. The two typical parity methods are even and odd. Even parity bits are set when an even number of bits are present in the transmitted data (often 1 byte = 8 bits).

particle velocity
the instantaneous velocity of a single molecule.

Pascal
a basic unit of pressure

Pascal’s law
any force applied to a fluid will be transmitted through the fluid and act on all enclosing surfaces.

PCB (Printed Circuit Board)
alternate layers of insulating materials, with wire layout patterns are built up

peak
to

peak level
the maximum pressure level for a cyclic variation

peer
to

performance variables
are parameters which define the operation of the part. Performance variables are used by the designer to measure whether the part will perform satisfactorily.

period
the time for a repeating pattern to go from beginning to end.

peripheral
devices added to computers for additional I/O.

permanent magnet
a magnet that retains a magnetic field when the original magnetizing force is removed.

petri
net

pH
a scale for determining is a solution is an acid or a base. 0

photocell
a device that will convert photons to electrical energy.

photoconductive cell
a device that has a resistance that will change as the number of incident photons changes.

photoelectric cell
a device that will convert photons to electrical energy.

photon
a single unit of light. Light is electromagnetic energy emitted as an electron orbit decays.

physical layer
an OSI network model layer.

PID (Proportional Integral Derivative)
a linear feedback control scheme that has gained popularity because of its relative simplicity.

piezoelectric
a material (crystals/ceramics) that will generate a charge when a force is applied. A common transducer material.

ping
an internet utility that makes a simple connection to a remote machine to see if it is reachable, and if it is operating.

pink noise
noise that has the same amount of energy for each octave.

piston
it will move inside a cylinder to convert a pressure to a mechanical motion or vice versa.

pitch
a perceptual term for describing frequency. Low pitch means low frequency, high pitch means a higher frequency.

pitot tube
a tube that is placed in a flow stream to measure flow pressure.

pixels
are picture elements in a digitally generated and displayed picture. A pixel is the smallest addressable dot on the display device.

PLA (Programmable Logic Array)
an integrated circuit that can be programmed to perform different logic functions.

plane sound wave
the sound wave lies on a plane, not on a sphere.

PLC (Programmable Logic Controller)
A rugged computer designs for control on the factory floor.

pneumatics
a technique for control and actuation that uses air or gases.

PNP
a bipolar junction transistor type. When referring to switching, these can be used to source current from a voltage source.

poise
a unit of dynamic viscosity.

polling
various inputs are checked in sequence for waiting inputs.

port
1. an undedicated connector that peripherals may be connected to. 2. a definable connection number for a machine, or a predefined value.

positive displacement pump
a pump that displaces a fixed volume of fluid.

positive logic
the normal method for logic implementation where 1 is a high voltage, and 0 is a low voltage.

potentiometer
displacement or rotation is measured by a change in resistance.

potting
a process where an area is filled with a material to seal it. An example is a sensor that is filled with epoxy to protect it from humidity.

power level
the power of a sound, relative to a reference level

power rating
this is generally the maximum power that a device can supply, or that it will require. Never exceed these values, as they may result in damaged equipment, fires, etc.

power supply
a device that converts power to a usable form. A typical type uses 115Vac and outputs a DC voltage to be used by circuitry.

PPP (Point
to

presentation layer
an OSI network model layer.

pressure
a force that is distributed over some area. This can be applied to solids and gases.

pressure based flow meter
uses difference in fluid pressures to measure speeds.

pressure switch
activated above/below a preset pressure level.

prioritized control
control operations are chosen on the basic of priorities.

procedural language
a computer language where instructions happen one after the other in a clear sequence.

process
a purposeful set of steps for some purpose. In engineering a process is often a machine, but not necessarily.

processor
a loose term for the CPU.

program
a sequential set of computer instructions designed to perform some task.

programmable controller
another name for a PLC, it can also refer to a dedicated controller that uses a custom programming language.

protocol
conventions for communication to ensure compatibility between separated computers.

proximity sensor
a sensor that will detect the presence of a mass nearby without contact. These use a variety of physical techniques including capacitance and inductance.

pull
up resistor

pulse
a brief change in a digital signal.

purge bubbling
a test to determine the pressure needed to force a gas into a liquid.

PVC
poly vinyl chloride

pyrometer
a device for measuring temperature

quality
a measure of how well a product meets its specifications. Keep in mind that a product that exceeds its specifications may not be higher quality.

R/W (Read/Write)
A digital line that is used to indicate if data on a bus is to be written to, or read from memory.

rack
a housing for holding electronics modules/cards.

rack fault
cards in racks often have error indicator lights that turn on when a fault has occurred. This allows fast replacement.

radiation
the transfer of energy or small particles (e.g., neutrons) directly through space.

radiation pyrometry
a technique for measuring temperature by detecting radiated heat.

radix
the base value of a numbering system. For example the radix of binary is 2.

RAID (Redundant Array of Inexpensive Disks)
a method for robust disk storage that would allow removal of any disk drive without the interruption of service, or loss of data.

RAM (Random Access Memory)
Computer memory that can be read from, and written to. This memory is the main memory type in computers. The most common types are volatile

random
scan devices

random noise
there are no periodic waveforms, frequency and magnitude vary randomly.

Rankine
A temperature system that uses absolute 0 as the base, and the scale is the same as the Fahrenheit scale.

raster devices
process pictures in parallel line scans. The picture is created by determining parts of the scene on each scan line and painting the picture in scan

rated
this will be used with other terms to indicate suggested target/maximum/minimum values for successful and safe operation.

Read/Write (R/W)
a digital device that can store and retrieve data, such as RAM.

reagent
an chemical used in one or more chemical reactions. these are often used for identifying other chemicals.

real
time

reciprocating
an oscillating linear motion.

redundancy
1. added data for checking accuracy. 2. extra system components or mechanisms added to decrease the chance of total system failure.

regenerative braking
the motor windings are reverse, and in effect return power to the power source. This is highly efficient when done properly.

register
a high speed storage area that can typically store a binary word for fast calculation. Registers are often part of the CPU.

regulator
a device to maintain power output conditions (such as voltage) regardless of the load.

relay
an electrical switch that comes in may different forms. The switch is activated by a magnetic coil that causes the switch to open or close.

relay
a magnetic coil driven switch. The input goes to a coil. When power is applied, the coil generates a magnetic field, and pulls a metal contact, overcoming a spring, and making contact with a terminal. The contact and terminal are separately wired to provide an output that is isolated from the input.

reliability
the probability of failure of a device.

relief valve
designed to open when a pressure is exceeded. In a hydraulic system this will dump fluid back in the reservoir and keep the system pressure constant.

repeatability
the ability of a system to return to the same value time after time. This can be measured with a standard deviation.

repeater
added into networks to boost signals, or reduce noise problems. In effect one can be added to the end of one wire, and by repeating the signals into another network, the second network wire has a full strength signal.

reset
a signal to computers that restarts the processor.

resistance
this is a measurable resistance to energy or mass transfer.

resistance heating
heat is generated by passing a current through a resistive material.

resolution
the smallest division or feature size in a system.

resonant frequency
the frequency at which the material will have the greatest response to an applied vibration or signal. This will often be the most likely frequency of self destruction.

response time
the time required for a system to respond to a directed change.

return
at the end of a subroutine, or interrupt, the program execution will return to where it branched.

reverberation
when a sound wave hits a surface, part is reflected, and part is absorbed. The reflected part will add to the general (reverberant) sound levels in the room.

Reynolds number
a dimensionless flow value based on fluid density and viscosity, flow rate and pipe diameter.

RF (Radio Frequency)
the frequency at which a magnetic field oscillates when it is used to transmit a signal. Normally this range is from about 1MHz up to the GHz.

RFI (Radio Frequency Interference)
radio and other changing magnetic fields can generate unwanted currents (and voltages) in wires. The resulting currents and voltages can interfere with the normal operation of an electrical device. Filters are often used to block these signals.

RGB (Red Green Blue)
three additive colors that can be used to simulate the other colors of the spectrum.

ripple voltage
when an AC voltage is converted to DC it is passed through diodes that rectify it, and then through capacitors that smooth it out. A small ripple still remains.

RISC (Reduced Instruction Set Computer)
the more standard computer chips were CISC (Complete Instruction Set Computers) but these had architecture problems that limited speed. To overcome this the total number of instructions were reduced, allowing RISC computers to execute faster, but at the cost of larger programs.

robustness
the ability of a system to deal with and recover from unexpected input conditions.

ROM (Read Only Memory)
Programs and data are permanently written.

ROM (Read Only Memory)
a permanent form of computer memory with contents that cannot be overwritten. All computers contain some ROM to store the basic operating system

rotameter
for measuring flow rate with a plug inside a tapered tube.

router
as network packets travel through a network, a router will direct them towards their destinations using algorithms.

RPC (Remote Procedure Call)
a connection to a specific port on a remote computer will request that a specific program be run. Typical examples are ping, mail, etc.

RS
232C

RS
422

RS
485

RTC (Real
Time Clock)

RTD (Resistance Temperature Detector)
as temperature is changed the resistance of many materials will also change. We can measure the resistance to determine the temperature.

RTS (Request To Send)
A data handshaking line that is used to indicate when a signal is ready for transmission, and clearance is requested.

rung
one level of logic in a ladder logic program or ladder diagram.