Program4 Engineering: Automation & Information Glossary

A B C D E F G H I J K L M N O P R S T U V W X

Item	From	Definition	Wag's Definition
AC	Alternating Current	Electrical power format in which the polarity of the supply (and therefore the current flow) reverses at a defined frequency. Virtually all utility power world-wide is AC. In the US, standard household current is 120VAC, 60 Hz.	Opposite of Ducey.
ACK	ACKnowldege	Confirmation signal that a signal or message (usually an alarm) was received.	Sound Bill the Cat makes when coughing up a hairball.
AD	Administrative Domain	Group of hosts, routers, and networks operated and managed by a single organization.	Those annoying parts of TV, Radio, and Web pages.
ADP	Active Display Page	Web page written in HTML contained in an Active Display Server on an Intranet.	very deep swimming hole exclamation
ANSI	American National Standards Institute	Organization composed of corporate, government, and other members that coordinates standards-related activities, approves U.S. national standards, and develops positions for the US in international standards organizations. ANSI is a member of the IEC and the ISO.	Impatient. Fidgety
API	Application Programming Interface.	Specification of function-call conventions that defines an interface to a service.	Wot a bloke is on payday.
ASCII	American Standard Code for Information Interchange. American Standard Code for Information Interchange.	Standard 8-bit code for character representation (7 bits plus parity). Commonly used to refer to text or string data.	Any four-year-old.
ATM	Asynchronous Transfer Mode.	International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells.	Where the green stuff comes from.
AUI	Attachment Unit Interface	Interface between an MAU (Media Attachment Unit) and a NIC (Network Card). The term AUI can also refer to the port to which an AUI cable might attach.	What you get when you fall down.
BCD	Binary Coded Decimal	A numbering format for representing decimal numbers with each digit represented by four bits. Six possible combinations are not used. 12-bit BCD is limited to 0-999, 16-bit to 0-9999.
BOOTP	Bootstrap Protocol	Protocol used by a network node to determine the IP address of its Ethernet interfaces, in order to affect network booting.	I'm not going there.
bpp	Bits Per Pixel	Used to specify digital image color palletes. The more bpp, the higher the number of colors that are possible.	Or there either!
BTU	British Thermal Unit	Standard measure of heat output or cooling capacity.
BTW	By The Way…	Short-hand phrase used in chat sessions and e-mail conversations.	British Thermal Whatchacallit
CAD	Computer Aided Drafting	Program used to design and produce engineering drawings and technical illustrations in 2D or 3D. The term "CAD/CAM" only applies when the result is used to drive numerically-controlled machine tools.	An unprincipled, ungentlemanly man.
CAN	Controller Area Network	"A multi-master broadcast serial bus system for networking ""intelligent"" devices as well as sensors and actuators within a system or sub-system originally designed for use in vehicles. "	1) The head, or in Britian, the loo. 2) To fire or lay off an employee.
CD-R	Compact Disc wRite	CD media that can be written to once per sector, but not erased or overwritten.
CD-ROM	Compact Disc Read-Only Memory	Read-Only CD media.
CD-RW	Compact Disc-Read/Write.	CD media that can be written to multiple times.
CGI	Common Gateway Interface	Set of rules describing how a Web server communicates with another application and vice versa. Any application can be a CGI program if it handles input and output according to the CGI standard.
CIP	Clean In Place	Automated electro-mechanical system that washes process equipment using hot water and solutions without requiring that the equipment be disassembled.
COM	Com Object Model	Microsoft's framework for developing and supporting program component objects. Provides the underlying services of interface negotiation, life cycle management (determining when an object can be removed from a system), licensing, and event services (putting one object into service as the result of an event that has happened to another object).
CRC	Cyclic Redundancy Check	Error-checking technique in which the recipient calculates a remainder by dividing received data by a prime binary divisor and compares the calculated remainder to a value stored in the message by the sending node.
CSV	Comma Separated Variable	Commonly used bare-bones text file format used for import from and import to spreadsheets and SQL databases where all data is in the form of ASCII text in random-length fields, separated by commas.	the drug stores found in most malls
dB	decibels	Unit used to express relative difference in power or intensity, usually between two acoustic or electric signals, equal to ten times the common logarithm of the ratio of the two levels.
DC	Direct Current	Electrical power format in which the polarity, and therefore the current flow, is constant. Solid state devices run on DC power.	Where W hangs out.
DCE	Data Circuit-terminating Equipment	Devices and connections that comprise the network or host end of the user-to-network or host interface. The DCE provides the clocking signal used to synchronize data transmission between DCE and DTE devices. Modems and interface cards are examples of DCE	Not a sure thing.
DCOM	Distributed Component Object Model.	Protocol that enables software components to communicate directly over a network. Developed by Microsoft and previously called Network OLE, DCOM is designed for use across multiple network transports, including Internet protocols such as HTTP.	What comes before de storm.
DCS	Distributed Control System	Mainframe or Mini-Computer based process control system, characterized by large I/O count and configuration using standard device definitions and templates.
DDE	Dynamic Data Exchange	An interprocess communication (IPC) protocol that uses shared memory as a common exchange area to move data between applications on a single machine.
DEC	Digital Equipment Corporation	One-time rival to IBM, DEC produced mainframe and minicomputers, notably the PDP and VAX lines, and was developer of the Alpha microprocessor and Alpha Server. Since its purchase by Compaq, it has all but disappeared as a brand name.	What you hit if anyone yells, "Incoming!"
DHCP	Dynamic Host Configuration Protocol.	A mechanism or server for allocating IP addresses dynamically so that addresses can be reused when hosts no longer need them.
DIN	Deutsche Industrie Norm	The German national standards organization.	Noise.
DIN connector	DIN	1) Multipin connector used in some Macintosh and IBM PC-compatible computers, and on some network processor panels. 2) Often used to refer to any (usually round) multipin connector.	The plug on your teenager's electric guitar.
DIP	Dual In-line Package	Common mounting method for integrated circuit chips and other components. Connections are made by two sets of "feet" protruding from opposite sides of the chip package. See "DIP Switch".	Many members of the IT department.
DLL	Dynamic Link Library.	A collection of small programs, any of which can be called when needed by a larger program that is running in the computer. DLL files that support specific device operation are known as device drivers.
DNA	Digital Network Architecture?	Network architecture developed by Digital Equipment Corporation. The products that embody DNA (including communications protocols) are collectively referred to as DECnet.	There is a Microsoft definition?
DNS	Domain Name System	System used in the Internet for translating names of network nodes into addresses.
DRAM	Dynamic Random-Access Memory	Solid state memory device that stores information in capacitors that must be periodically refreshed.	Ah, yes Laddie, just a wee one!
DSL	Digital Subscriber Line	Public network technology that delivers high bandwidth over conventional copper wiring at limited distances. There are four types of DSL: ADSL, HDSL, SDSL, and VDSL. All are provisioned via modem pairs, with one modem located at a central office and the other at the customer site.
DTE	Data Terminal Equipment.	Device at the user end of a user-network or user-host interface that serves as a data source, destination, or both. DTE connects to a data network through a DCE device (for example, a modem) and typically uses clocking signals generated by the DCE. DTE includes such devices as computers, protocol translators, and multiplexers.
EEPROM	Electrically Erasable Programmable Read-Only Memory	EPROM that can be erased using electrical signals applied to specific pins.
EIA	Electronic Industries Association	Group that specifies electrical transmission standards.
EISA	Extended Industry-Standard Architecture	32-bit bus interface used in PCs, PC-based servers, and some UNIX workstations and servers.
EMI	Electro-Magnetic Interference	Interference by electromagnetic signals that can cause reduced data integrity and increased error rates on transmission channels.	The guys that brought us the Fab Four.
EPROM	Erasable Programmable Read-Only Memory	Memory chips that can programmed but can be erased by some means and reprogrammed if needed.
ESD	ElectroStatic Discharge.	Discharge of stored static electricity. Can damage electronic equipment and corrumpt stored data, resulting in complete or intermittent failures.
FAQ	Frequently Asked Questions	Usually appears in the form of a "read-me" file in a variety of Internet forums.	Joe Friday's favorite.
FDDI	Fiber Distributed Data Interface	LAN standard, defined by ANSI X3T9.5, specifying a 100-Mbps token-passing network using fiber-optic cable, with transmission distances of up to 2 km.	Old fashioned. Drab.
FIFO	First-In, First-Out	A buffering scheme where the first item entering the buffer is the first item retrieved.	fido's brother
FTP	File Transfer Protocol.	Part of the TCP/IP protocol stack, used for transferring files between network nodes.
GB	GigaByte	"A measure of computer data storage capacity, approximately a billion bytes. A true gigabyte is 2 to the 30th power, or 1,073,741,824 in decimal notation. "	Three Austrailian brothers looking in the mirror.
GHz	GigaHertz	A unit of frequency equal to one thousand million hertz (1,000,000,000 Hz).
GIF	Graphic Interface Format	Graphic file format that uses non-lossy compression and can display static or animated images. Used in web pages to display graphic elements. Limited to 256 colors or shades of grey.	A popular brand of peanut butter.
GUI	Graphical User Interface	User environment that uses pictorial as well as textual representations of the input and output of applications or processes. Conventions such as buttons, icons, and windows are typical, and many actions are performed using a pointing device (such as a mouse).	What you get when your ice cream cone melts faster than you can eat it.
HDD	Hard Disk Drive	Standard storage medium in computers, usually not removable.
HMI	Human/Machine Interface	Computer or terminal that provides point of control interface between human operator and a machine or automated process. Can also refer to the software or application running on such an interface. Also known as OI (Operator Interface) and MM (Man/Machine Interface).
HTML	HyperText Markup Language.	Document formatting language that uses tags to indicate how a given part of a document should be interpreted by a viewing application, such as a Web browser.
HTTP	HyperText Transfer Protocol.	The protocol used by Web browsers and Web servers to transfer files, such as text and graphic files.
I/O	Input/Output.	In PLC and DCS systems, the hardware that provides interface between the controlling hardware and field instrumentation.
IEC	International Electrotechnical Commission	Industry group that writes and distributes standards for electrical products and components
IEEE	Institute of Electrical and Electronics Engineers.	Professional organization whose activities include the development of communications and network standards.	Carumba!
IEEE 802.3		IEEE LAN protocol that specifies an implementation of the physical layer and the MAC sublayer of the data link layer of what we know as Ethernet. Extensions to the IEEE 802.3 standard specify implementations for Fast Ethernet.
IMHO	"In My Humble Opinion."	Short-form phrase seen in e-mail messages, newsgroups, etc.
IP	Internet Protocol	Network layer protocol in the TCP/IP stack offering a connectionless internetwork service. IP provides features for addressing, type-of-service specification, fragmentation and reassembly, and security. See "IP Address".
IPX	Internetwork Packet Exchange.	NetWare network layer (Layer 3) protocol used for transferring data from servers to workstations.
IS	Information Systems	Sometimes used to describe the department that installs and maintains a company's computer hardware, network, and software systems. Also called "IT" for "Information Technology".
ISA	Industry-Standard Architecture.	A 16-bit bus used for Intel-based personal computers. Also used to refer to an expansion card that conforms to this bus format.
ISA	Instrument Society of America	ISA is an international, nonprofit, educational organization. The Society fosters advancement in the theory, design, manufacture, and use of instruments, computers, and systems for measurement and control.
ISDN	Integrated Services Digital Network.	Communication protocol, offered by telephone companies, that permits telephone networks to carry data, voice, and other source traffic.
ISO	International Organization for Standardization.	International organization that is responsible for a wide range of standards, including the ISO 9000 series of standards for quality management and quality assurance.
ISO 9000		Set of international quality-management standards defined by ISO. The standards, which are not specific to any country, industry, or product, allow companies to demonstrate that they have specific processes in place to maintain an efficient quality system.
ISP	Internet Service Provider	Any company that provides Internet access to other companies and individuals.
IT	Information Technology	See "IS".
ITU	International Telecommunication Union.	An organization established by the United Nations, headquartered in Geneva, Switzerland which allows governments and the private sector to coordinate global telecom networks and services.
JPEG	Joint Photographics Expert Group	Graphic file format that is used to compress still images. Uses "lossy" compression but support high color resolutions (24 and 32 bpp).	what you hang a jay from…
KB	KiloByte	Roughly a thousand bytes (actually, 2 to the 10th power, or decimal 1,024 bytes).
LAN	Local-Area Network	High-speed, low-error data network covering a relatively small geographic area (up to a few thousand meters). LANs connect workstations, peripherals, terminals, and other devices in a single building or other geographically limited area.	What seasick sailors can't wait to get back to.
LCD	Liquid Crystal Display	Display device that uses liquid crystal sealed between two pieces of glass. Relies on reflected ambient light or backlighting to provide visibility.
LED	Light Emitting Diode.	Low-power, long-life semiconductor device that emits light when current passes through it. Most emit light at a single wavelength, and colors range from blue-violet to red to infrared.
LSD	Least Significant Digit	The lowest weighted digit in a numerical value. For instance for 12345, "5" is the LSD.	Timmy's favorite.
MAC address	Media Access Control address	Standardized data link layer address that is required for every port or device that connects to an Ethernet LAN. MAC addresses are 6 bytes long and are controlled by the IEEE. Also known as a hardware address, MAC-layer address, and physical address.	Location of the nearest Micky-D's.
MAP	Manufacturing Automation Protocol	Network architecture created by General Motors to meet the specific needs of the factory floor. MAP specifies a token-passing LAN similar to IEEE 802.4.	What your significant other never manages to fold back up.
MAU	Media Attachment Unit	Device used in Ethernet networks that provides the interface between the AUI port of a station and the common medium of the Ethernet. Sometimes called a "transceiver".	Nice place to vacation.
MB	MegaByte	As a measure of real and virtual memory, a megabyte is 2 to the 20th power byte, or 1,048,576 bytes in decimal notation, although when used to describe disk storage capacity and transmission rates, a megabyte is often 1,000,000 bytes in decimal notation.
MES	Manufacturing Execution System	A type of software that provides tools for tracking products through the manufacturing process, modeling or defining the process, maintaining a record of the process, performing document management and scheduling.
MIME	Multipurpose Internet Mail Extension	Standard for transmitting non-text data (or data that cannot be represented in plain ASCII code) in Internet mail, such as binary, foreign language text (such as Russian or Chinese), audio, or video data.	Those annoying guys in tights and pancake.
MMI	Man/Machine Interface	See HMI.
MPEG	Motion Picture Experts Group	A group that sets standards for compressing video (and audio). MPEG1 is a bit stream standard for compressed video and audio optimized to fit into a bandwidth of 1.5 Mbps. The popular MP3 (MPEG-1, audio layer-3) audio file is a part of these standards.
MSD	Most Significant Digit	The highest weighted digit in a numerical value. For instance for 12345, "1" is the MSD.
MTBF	Mean Time Between Failure.	A measure of how reliable a hardware product or component is, expressed as the average measured or expected number of hours between failures.	That soul group from the '70s. (MFSB)
NDIS	Network Driver Interface Specification	Microsoft specification for a generic, hardware- and protocol-independent device driver for NICs	N Dat, too.
NetBEUI	NetBIOS Extended User Interface.	Enhanced version of the NetBIOS protocol used by network operating systems such as LAN Manager, LAN Server, Windows for Workgroups, and Windows NT.	What happens if you don't look before you cast.
NetBIOS	Network Basic Input/Output System	API used by applications on an IBM LAN to request services from lower-level network processes. These services might include session establishment and termination, and information transfer.	the scoop on talking tv heads.
NIC	Network Interface Card.	PC expansion board that provides network communication capabilities to and from a computer system. Sometimes called a network adapter.	TV network your kids watch.
NOS	Network Operating System	Generic term used to refer to what are really distributed file systems. Examples are NetWare, Banyan VINES, Windows Networking.	What gets stuffed up during flu season.
NTSC	National Television Standards Committee	1) The organization that set the standard for Television broadcasting in the US. 2) Generally, that video standard or format. An NTSC TV image has 525 horizontal lines per frame. Every other line is skipped, therefore takes two screen scans to complete a frame. The complete frame is scanned every 1/30 second.
ODBC	Open DataBase Connectivity.	Standard application programming interface for accessing data in both relational and nonrelational database systems. Using this API, applications can access data stored in database systems on a variety of computers even if each database system uses a different data storage format and programming interface.	too much barney ruble.
OI	Operator Interface	See HMI.	Vey!
OOTB	Out-Of-The-Box.	Default configuration of the product when it is first installed.
PBX	Private Branch Exchange	Digital or analog telephone switchboard located on the subscriber premises and used to connect private and public telephone networks.	sandwich of peanut butter & the unknown
PC	Personal Computer	In general, any stand-alone computer, either desktop or portable. Common usage implies that the machine being referred to is based on the IBM/Intel architecture. Other types are typically referred to by their brand names, i.e. "Mac". See "PLC".
PCI	Peripheral Component Interconnect	Latest bus standard for expansion card connection in Intel PCs. Transmits 32 bits at a time in a 124-pin connection (the extra pins are for power supply and grounding) and 64 bits in a 188-pin connection in an expanded implementation.
PCM	Pulse Code Modulation	"1) In general, transmission of analog information in digital form through sampling and encoding the samples with a fixed number of bits. 2) Technique of encoding analog voice into a 64-kbit data stream by sampling with eight-bit resolution at a rate of 8000 times per second."
ping	Packet INternet Groper	Command-line command that sends ICMP (Internet Control Message Protocol) echo message and its reply. Often used in IP networks to test the reachability of a network device.	A popular brand of golf equipment.
PLC	Programmable Logic Controller	A specialized computer used for machine and process control that has no operator interface (keyboard, monitor, mouse), but has an Input/Output structure that connects to real-world devices such as switches, sensors, valves, motor starters, and actuators. Originally called a PC, for Programmable Controller. PLC was a registered trademark of the Allen-Bradley company, but was realeased by them for general us after IBM appropriated "PC" to mean Personal Computer, not Programmable Controller.
POP	Post Office Protocol	Protocol that client e-mail applications use to retrieve mail from a mail server.	One of the three Rice Krispies guys.
PPP	Point-to-Point Protocol.	Protocol that provides router-to-router and host-to-network connections over synchronous and asynchronous circuits.
PROM	Programmable Read-Only Memory	Solid state memory device that can be programmed using special equipment. PROMs can be programmed only once, but once programmed or "burned", retain their contents indefinitely.	I hope Carrie stays home!
RAID	Redundant Array of Inexpensive Drives	Multiple standard Hard Disk Drives in combination for improved speed and/or fault tolerance. In most configurations, the failure of one drive does not result in a loss of data.	Kills bugs dead.
RAM	Random Access Memory	Volitile solid-state memory device for holding data in binary format.
RAS	Remote Access Services	A feature built into Windows NT that enables users to log into an NT-based LAN using a modem, X.25 connection or WAN link.
RAS	Remote Access Server	A server that is dedicated to handling users that are not on a LAN but need remote access to it via dial-up connections.
RFI	Radio Frequency Interference	Radio frequencies that create noise that interferes with information being transmitted across unshielded copper cable.
RISC	Reduced Instruction Set Computer	A microprocessor designed to perform a smaller number of types of computer instruction so that it can operate at a higher speed.	That interminable board game where you try to take over the world.
RJ connector	Registered Jack connector	Standard connectors originally used to connect telephone lines. RJ connectors are now used for telephone connections and for 10BaseT and other types of network connections. RJ-45 is the standard 10Base-T Ethernet connector.
ROM	Read-Only Memory	Storage memory that can be read, but not written to.
RPC	Remote-Procedure Call	Procedure calls that are built or specified by clients and executed on servers, with the results returned over the network to the clients. The basis for client/server computing.
RTFM	Read The (ahem) Fabulous Manual.	"When all else fails, RTFM!"
SAP	Service Advertising Protocol	IPX protocol that provides a means of informing network clients, via routers and servers, of available network resources and services.
SAP	(Probably something in German. They aren't telling.)	Large German software company that sells and installs a software suite that manages financial, asset, and cost accounting, production operations and materials, personnel, plants, and archived documents. Commonly used to refer to an installed SAP application.
SCADA	Supervisory Control And Data Acquisition	A combination of software application and hardware for process control, that gathers data in real time from remote process equipment, and provides the means for overall control and monitoring of the process.
SECAM	Sequential Couleur avec Memoire	TV system used in France and countries of the former Soviet Union, and certain other countries. SECAM uses 625 scan lines per frame.
SGML	Standardized Generalized Markup Language	International standard for the definition of system-independent, device-independent methods of representing text in electronic form.
SIM	Service Improvement Module	Intellution's term for a software upgrade issued between published revisions to address one or more specific problems.
SIMM	Single In-line Memory Module	RAM memory package format commonly used in PCs, consisting of several memory chips mounted on a small circuit board, with contacts along one edge.
SMTP	Simple Mail Transfer Protocol	A TCP/IP protocol used in sending and receiving e-mail. Because it is limited in its ability to queue messages at the receiving end, it is usually only used for sending mail, and POP or IMAP (Internet Message Access Protocol) are used to retreive mail.
SNMP	Simple Network Management Protocol.	Network management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.
SQL	Structured Query Language	International standard language for defining and accessing relational databases.
SRAM	Static Random Access Memory	Type of RAM that retains its contents for as long as power is supplied. SRAM does not require constant refreshing, like DRAM.
STP	Shielded Twisted-Pair.	Two-pair wiring medium used in a variety of network implementations. STP cabling has a layer of shielded insulation to reduce EMI.
TCP	Transmission Control Protocol	Connection-oriented transport layer protocol that provides reliable full-duplex data transmission. TCP is part of the TCP/IP protocol stack.
TCP/IP	Transmission Control Protocol/Internet Protocol	Common name for the suite of protocols developed by the U.S. Department of Defence in the 1970s to support the construction of worldwide internetworks. TCP and IP are the two best-known protocols in the suite.
TDR	Time Domain Reflectometer	Device capable of sending signals through a network medium to check cable continuity and other attributes. TDRs are used to find physical layer network problems.
UART	Universal Asynchronous Receiver/Transmitter	Integrated circuit, attached to the parallel bus of a computer, used for serial communications.
UL	Underwriters Laboratories	Independent agency within the United States that tests product safety.
UNIX	(Reportedly a pun based on an earlier system named "Multics", it doesn't stand for anything.)	Operating system developed in 1969 at Bell Laboratories, and the first to be written in C. UNIX is an open source entitiy, meaning that the source code has been published, and deveopers can modify for their own purposes if they desire. UNIX has gone through several iterations since its inception. While originally intended for mainframe and mini-computers, variants or "flavors" such as LINUX have been developed for PC platforms. The "official" trademarked UNIX is now owned by the The Open Group, an industry standards organization, which certifies and brands UNIX implementations.
UPS	Uninterruptable Power Supply	UPS contains a battery and an AC inverter to supply AC power to a computer or other equipment for a limited time during a power outage.	Not to be confused with the guys in the brown trucks who bring you your computer when you but it by phone or mail order!
URL	Universal Resource Locator	Standardized addressing scheme for accessing hypertext documents and other services using a browser. Sometimes referred to as a "web address", for example "http:\\www.program4.com".
UTP	Unshielded Twisted Pair	Four-pair wire medium commonly used in networking. Does not require the fixed spacing between connections. Termed "Category 1" through "Category 5".
VAC	Volts Alternating Current	Measurement of AC voltage or potential. Since AC voltage is constantly changing, the measurement is differential, or peak-to-peak.	what you sweep with
VAX	Virtual Address eXtension	A line of 32-bit mid-range server computers from the Digital Equipment Corporation (DEC).
VB	Visual Basic	Microsoft's object-oriented programming language/environment based on the BASIC language.
VBA	Visual Basic for Applications	A subset of Visual Basic included in Microsoft (and other's) software packages as the Macro language.
VMS	Virtual Memory System	Digital Equipment Corporation's (DEC) 32-bit operating system for its VAX computers, both introduced in 1979. Revised to run on the Alpha chip and renamed OpenVMS.
VPN	Virtual Private Network	Enables IP traffic to travel securely over a public TCP/IP network by encrypting all traffic from one network to another. A VPN uses "tunneling" to encrypt all information at the IP level.
WAN	Wide-Area Network	Data communications network that serves users across a broad geographic area and often uses transmission devices provided by common carriers.
WORM	Write Once Read Many	Any storage medium whose data can not be altered once written, but can be read any number of times. A CD-ROM is a WORM device.
WWW	World Wide Web	Large network of Internet servers providing hypertext and other services to terminals running client applications such as a browser. Also know as the Internet or simply "the Net".
XML	eXtensible Markup Language	Text markup language designed to enable the use of SGML on the World-Wide Web. XML allows you to define your own customized markup language.

# A B C D E F G H I J K L M N O P Q R S T U V W X

Item	Definition
100BaseFX	100-Mbps baseband Fast Ethernet specification using two strands of multimode fiber-optic cable per link. To guarantee proper signal timing, a 100BaseFX link cannot exceed 1312 feet (400 meters) in length.
100BaseT	100-Mbps baseband Fast Ethernet specification using UTP wiring.
10Base2	10-Mbps baseband Ethernet specification using 50-ohm thin coaxial cable. has a distance limit of 606.8 feet (185 meters) per segment
10Base5	10-Mbps baseband Ethernet specification using standard (thick) 50-ohm baseband coaxial cable. has a distance limit of 1640 feet (500 meters) per segment
10BaseT	10-Mbps baseband Ethernet specification using two pairs of twisted-pair cabling (Category 3, 4, or 5): one pair for transmitting data and the other for receiving data. Has a distance limit of approximately 328 feet (100 meters) per segment.
ActiveX	Microsoft's Windows-specific non-Java technique for writing applets.
address	Data structure or logical convention used to identify a unique entity, such as a particular process or network device
address mask	Bit combination used to describe which portion of an address refers to the network or subnet and which part refers to the host. Sometimes referred to simply as mask.
algorithm	Well-defined rule or process for arriving at a solution to a problem.
anonymous FTP	Allows a user to retrieve documents, files, programs, and other archived data from anywhere on the Internet without having to establish a userid and password.
applet	Small program, often used in the context of a Java-based program, that is compiled and embedded in an HTML page.
application	Program that performs a function directly for a user.
architecture	overall structure of a computer or communication system.
asynchronous	In general, having a lack of temoral concurrence, or happening at different times. In computing, signals or events that are not time-coordinated.
asynchronous transmission	Term describing digital signals that are transmitted without precise clocking. Such signals generally have different frequencies and phase relationships. Asynchronous transmissions usually encapsulate individual characters in control bits (called start and stop bits) that designate the beginning and end of each character.
attenuation	Loss of communication signal energy.
backbone	Part of a network that acts as the primary path for traffic that is most often sourced from, and destined for, other networks.
backplane	Physical connection between an interface processor or card and the data buses and the power distribution buses inside a chassis.
balun	Device used for matching impedance between a balanced and an unbalanced line, usually twisted-pair and coaxial cable.From BALanced, Unbalanced
bandwidth	Difference between the highest and lowest frequencies available for network signals. The term is also used to describe the rated throughput capacity of a given network medium or protocol.
baseband	Characteristic of a network technology where only one carrier frequency is used. Ethernet is an example of a baseband network. Also called narrowband.
baud	Unit of signaling speed equal to the number of discrete signal elements transmitted per second. Baud is synonymous with bits per second (bps) if each signal element represents exactly 1 bit.
binary	Numbering system characterized by ones and zeros (1 = on, 0 = off). In PLCs, often a reference to a boolean data type.
bit	Binary digit used in the binary numbering system. Can be 0 or 1.
BNC connector	Standard connector used to connect IEEE 802.3 10Base2 coaxial cable to an MAU.
bridge	Device that connects and passes packets between two network segments that use the same communications protocol. Bridges operate at the data link layer (Layer 2) of the OSI reference model.
broadband	1) Transmission system that multiplexes multiple independent signals onto one cable. 2) A coaxial cable on which analog signaling is used.
broadcast	Data packet that will be sent to all nodes on a network.
broadcast storm	Undesirable network event in which many broadcasts are sent simultaneously across all network segments. A broadcast storm uses substantial network bandwidth and, typically, causes network time-outs.
browser	GUI-based hypertext client application, such as Internet Explorer, Mosaic, and Netscape Navigator, used to access hypertext documents and other services located on innumerable remote servers throughout the WWW and Internet.
buffer	Storage area used for handling data in transit. Buffers are used in internetworking to compensate for differences in processing speed between network devices.
build	In programming, a specific instance of a compiled program. Subset of a Version.
bus	Common physical signal path composed of wires or other media across which signals can be sent from one part of a computer to another.
byte	Term used to refer to a series of consecutive binary digits that are operated upon as a unit (for example, an 8-bit byte).
byte reversal	Process of storing numeric data with the least-significant byte first. Used for integers and addresses on devices with Intel microprocessors.
caching	1) Form of replication in which information learned during a previous transaction is used to process later transactions. 2) Storage recently-used of information in a short-term memory area or disk file for rapid retrieval should it be needed again.
Category 1 cabling	One of five grades of UTP cabling. used for telephone communications and is not suitable for transmitting data. Also known as "CAT-1".
Category 2 cabling	One of five grades of UTP cabling. capable of transmitting data at speeds up to 4 Mbps. Also known as "CAT-2".
Category 3 cabling	One of five grades of UTP cabling. used in 10BaseT networks and can transmit data at speeds up to 10 Mbps. Also known as "CAT-3".
Category 4 cabling	One of five grades of UTP cabling. used in Token Ring networks and can transmit data at speeds up to 16 Mbps. Also known as "CAT-4".
Category 5 cabling	One of five grades of UTP cabling. can transmit data at speeds up to 100 Mbps. Also known as "CAT-5".
checksum	Method for checking the integrity of transmitted data. A checksum is an integer value computed from a sequence of octets taken through a series of arithmetic operations. The value is recomputed at the receiving end and compared for verification.
circuit	Path between two or more points.
client	Node or software program (front-end device) that requests services from a server.
client/server computing	Term used to describe distributed computing (processing) network systems in which transaction responsibilities are divided into two parts: client (front end) and server (back end). Both terms (client and server) can be applied to software programs or actual computing devices.
coaxial cable	Cable consisting of a hollow outer cylindrical conductor that surrounds a single inner wire conductor. Two types of coaxial cable are currently used in LANs: 50-ohm cable, which is used for digital signaling, and 75-ohm cable, which is used for analog signaling and high-speed digital signaling.
codec	Integrated circuit device that typically uses pulse code modulation to transform analog signals into a digital bit stream and digital signals back into analog signals. From coder-decoder
collision	In Ethernet, the result of two nodes transmitting simultaneously. The frames from each device impact and are damaged when they meet on the physical media.
collision domain	In Ethernet, the network area within which frames that have collided are propagated. Repeaters and hubs propagate collisions; LAN switches, bridges and routers do not.
companding	Contraction derived from the opposite processes of compression and expansion. Part of the PCM process whereby analog signal values are logically rounded to discrete scale-step values on a nonlinear scale. The decimal step number is then coded in its binary equivalent prior to transmission. The process is reversed at the receiving terminal using the same nonlinear scale.
component	In object-oriented programming and distributed object technology, a component is a reusable program building block that can be combined with other components in the same or other computers in a distributed network to form an application.
compression	The running of a data set through an algorithm that reduces the space required to store or the bandwidth required to transmit the data set.
concatenate	The process of joining two pieces of string data together by adding one to the end of the other.
concentrator	See "hub".
connectionless	Term used to describe data transfer without the existence of a virtual circuit.
connection-oriented	Term used to describe data transfer that requires the establishment of a virtual circuit.
contention	Access method in which network devices compete for permission to access the physical medium.
ControlNet	Allen-Bradley's high-speed communications network for remote I/O and peer-to-peer communications.
cookie	Piece of information sent by a Web server to a Web browser that the browser is expected to save and send back to the Web server whenever the browser makes additional requests of the Web server.
cross talk	Interfering energy transferred from one circuit to another.
Cyberspace	Term coined by William Gibson in his fantasy novel Neuromancer to describe the "world" of computers and the society that gathers around them. Often used to refer to the Internet, the World Wide Web, or some combination thereof.
database	A collection of data that is organized into one or more tables, so that its contents can easily be accessed, managed, and updated.
database object	Piece of information that is stored in a database.
DB connector	Type of connector used to connect serial and parallel cables to a data bus. DB connector names are in the format DB-x, where x represents the number of wires within the connector. Each line is connected to a pin on the connector, but in many cases, not all pins are assigned a function. From Data Bus connector
decimal	Base 10 numbering system. Uses arabic numerals 0-9. Decimal refers to whole numbers. Fractional numbers (those containing a decimal point) are referred to as "floating point".
decryption	Reverse application of an encryption algorithm to encrypted data, thereby restoring that data to its original, unencrypted state.
demodulation	Process of returning a modulated signal to its original form. Modems perform demodulation by taking an analog signal and returning it to its original (digital) form.
demultiplexing	Separating of multiple input streams that were multiplexed into a common physical signal back into multiple output streams.
DeviceNet	A flexible, open, low-level network that provides connections between simple industrial devices (such as sensors and actuators) and higher-level devices (such as PLC controllers and computers).
dial-up line	Communications circuit that is established by a switched-circuit connection using the telephone company network.
DIP Switch	Small set of two-position switches contained in a DIP-mount component that can be monunted on a circuit board. Commonly used to set options or configure a piece of hardware.
domain	In the Internet, a portion of the naming hierarchy tree that refers to general groupings of networks based on organization-type or geography.
dot address	Refers to the common notation for IP addresses in the form n.n.n.n where neach number n represents, in decimal, 1 byte of the 4-byte IP address.
drop	Point on a multipoint channel where a connection to a networked device is made.
encoder	Device that modifies information into the required transmission format.
encryption	Application of a specific algorithm to data so as to alter the appearance of the data making it incomprehensible to those who are not authorized to see the information.
enterprise network	Large and diverse network connecting most major points in a company or other organization. Differs from a WAN in that it is privately owned and maintained.
Ethernet	Baseband LAN specification invented by Xerox Corporation and developed jointly by Xerox, Intel, and Digital Equipment Corporation. Ethernet networks use CSMA/CD and run over a variety of cable types at 10 Mbps. Ethernet is similar to the IEEE 802.3 series of standards.
Fast Ethernet	Any of a number of 100-Mbps Ethernet specifications. Fast Ethernet offers a speed increase ten times that of the 10BaseT Ethernet specification, while preserving such qualities as frame format, MAC mechanisms, and MTU. Such similarities allow the use of existing 10BaseT applications and network management tools on Fast Ethernet networks. Based on an extension to the IEEE 802.3 specification.
fiber-optic cable	Physical medium capable of conducting modulated light transmission. Compared with other transmission media, fiber-optic cable is more expensive, but is not susceptible to electromagnetic interference, and is capable of higher data rates.
field	1) In database parlance, an individual piece of data contained in a record. 2) In general, the plant floor, installation site, or real world.
Fieldbus	Generically, any network intended to allow communication between industrial devices in automation or process control. DeviceNet, ControNet, Modbus, etc. are all technically fieldbuses. "Foundation Fieldbus" is a specific open implementation specified and promoted by the non-profit Fieldbus Foundation.
firewall	Router or access server, or several routers or access servers, designated as a buffer between any connected public networks and a private network. A firewall router uses access lists and other methods to ensure the security of the private network.
firmware	Software instructions set permanently or semipermanently in ROM
flash memory	Nonvolatile storage that can be electrically erased and reprogrammed so that software images can be stored, booted, and rewritten as necessary.
flat file	A file containing records that have no structured interrelationship, or text that has no formatting information.
floating point	A data type capable of holding fractional values.
full duplex	Capability for simultaneous data transmission between a sending station and a receiving station.
gateway	In the IP community, an older term referring to a routing device. Today, the term router is used to describe nodes that perform this function, and gateway refers to a special-purpose device that performs an application layer conversion of information from one protocol stack to another.
half duplex	Capability for data transmission in only one direction at a time between a sending station and a receiving station.
handshake	Sequence of messages exchanged between two or more network devices to ensure transmission synchronization.
header	1) Control information placed before data when encapsulating that data for network transmission. 2) Routing information that appears at the top or beginning of an email or other message.
hertz	Measure of frequency. Abbreviated Hz. Synonymous with cycles per second.
hexidecimal	Base 16 numbering system. Uses arabic numerals 0-9, plus letters A-F. Each digit represents four bits, of which there are 16 possible combinations. Hexadecimal numbers have either and 0x prefix or an h suffix.
hierarchical addressing	Scheme of addressing that uses a logical hierarchy to determine location. For example, IP addresses consist of network numbers, subnet numbers, and host numbers, which IP routing algorithms use to route the packet to the appropriate location.
hop	Passage of a data packet between two network nodes (for example, between two routers).
hop count	Routing metric used to measure the distance between a source and a destination.
host	Computer system on a network. Similar to node, except that host usually implies a computer system, whereas node generally applies to any networked system, including access servers and routers. 2) Sometimes synonymous with Server.
host name	Name given to a machine.
hub	In Ethernet and IEEE 802.3, an Ethernet multiport repeater, sometimes called a concentrator.
hyperlink	Pointer within a hypertext document that points (links) to another document, which may or may not also be a hypertext document.
hypertext	Electronically-stored text that allows direct access to other texts by way of encoded links. Hypertext documents can be created using HTML, and often integrate images, sound, and other media that are commonly viewed using a browser.
infrared	Electromagnetic waves whose frequency range is above that of microwaves, but below that of the visible spectrum.
integer	A whole number. In a computer or PLC, the range of an integer is determined by the number of bits in the storage word. The range of a standard 16-bit integer is -32,768 to 32,767 (signed) or 0 to 65,536 (unsigned).
interface	Connection between two systems or devices.
Internet protocol	Any protocol that is part of the TCP/IP protocol stack.
internetwork	Collection of networks interconnected by routers and other devices that functions (generally) as a single network. Sometimes called an internet, which is not to be confused with the Internet.
IP address	32-bit address assigned to hosts using TCP/IP. An IP address is written as 4 three-digit (or less) numbers separated by periods (dotted decimal format). Each address consists of a network number, an optional subnetwork number, and a host number. The network and subnetwork numbers together are used for routing, while the host number is used to address an individual host within the network or subnetwork. Also called an Internet address.
jabber	Error condition in which a network device continually transmits random, meaningless data onto the network.
Java	Object-oriented programming language developed at Sun Microsystems to solve a number of problems in modern programming practice. The Java language is used extensively on World-Wide Web, particularly for applets.
jitter	Analog communication line distortion caused by the variation of a signal from its reference timing positions.
jumper	Electrical switch consisting of a number of pins and a connector that can be attached to the pins in a variety of different ways. Different circuits are created by attaching the connector to different pins.
Kermit	Popular file-transfer and terminal-emulation program
lossy	1) Characteristic of a network that is prone to lose packets when it becomes highly loaded. 2) Compression method that results in data loss. Non-lossy compression results in no data loss.
modem	Device that converts digital and analog signals. At the source, a modem converts digital signals to a form suitable for transmission over analog communication facilities. At the destination, the analog signals are returned to their digital form. Modems allow data to be transmitted over voice-grade telephone lines. From Modulator-Demodulator
multiplexing	Scheme that allows multiple logical signals to be transmitted simultaneously across a single physical channel.
mux	Combines multiple signals for transmission over a single line. The signals are demultiplexed, or separated, at the receiving end. From Multiplexing Device.
name resolution	Generally, the process of associating a name with a network location.
name server	Server connected to a network that resolves network names into network addresses.
NetWare	Popular distributed NOS developed by Novell. Provides transparent remote file access and numerous other distributed network services.
network	Collection of computers, printers, routers, switches, and other devices that are able to communicate with each other over some transmission medium.
node	Endpoint of a network connection or a junction common to two or more lines in a network. Nodes can be processors, controllers, or workstations. Nodes, which vary in routing and other functional capabilities, can be interconnected by links, and serve as control points in the network. Node is sometimes used generically to refer to any entity that can access a network, and is frequently used interchangeably with device.
null modem	Small box or cable used to join computing devices directly, rather than over a network
octal	Base 8 numbering system. Uses arabic numerals 0-7. Each digit is represented by three bits, of which there are 8 possible combinations. Early PLCs used octal numbering exclusively.
open architecture	Architecture with which third-party developers can legally develop products and for which public domain specifications exist.
packet	Logical grouping of information that includes a header containing control information and (usually) user data. Packets are most often used to refer to network layer units of data.
packet switch	WAN device that routes packets along the most efficient path and allows a communications channel to be shared by multiple connections.
packet switching	Networking method in which nodes share bandwidth with each other by sending packets.
parity check	Process for checking the integrity of a character. A parity check involves appending a bit that makes the total number of binary 1 digits in a character or word (excluding the parity bit) either odd (for odd parity) or even (for even parity).
path name	Full name of a DOS, Mac OS, or UNIX file or directory, including all directory and subdirectory names. Consecutive names in a path name are typically separated by a backslash (\) for DOS, a colon (:) for Mac OS, and a forward slash (/) for UNIX.
peer-to-peer computing	Calls for each network device to run both client and server portions of an application. Also describes communication between implementations of the same OSI reference model layer in two different network devices.
policy	Any defined rule that determines the use of resources within the network. A policy can be based on a user, device, subnetwork, network, or application.
polling	Access method in which a primary network device inquires, in an orderly fashion, whether secondaries have data to transmit. The inquiry occurs in the form of a message to each secondary that gives the secondary the right to transmit.
port	"1) Interface plug or socket on a computer device. 2) To rewrite software or microcode so that it will run on a different hardware platform or in a different software environment than that for which it was originally designed. "
protocol	Formal description of a set of rules and conventions that govern how devices on a network exchange information
proxy server	Intermediary program that acts as both a server and a client for the purpose of making requests on behalf of other clients. Requests are serviced internally or by passing them on, possibly after translation, to other servers. A proxy interprets, and, if necessary, rewrites a request message before forwarding it.
query	Message used to inquire about the value of some variable or set of variables.
queue	Generally, an ordered list of elements waiting to be processed.
record	In database parlance, set of related fields that describe a particular entity.
recovery	Way that a system or device resumes operation after overcoming a hardware or software problem.
redundancy	Duplication of devices or connections so that, in the event of a failure, the redundant devices, services, or connections can perform the work of those that failed
register	A word of memory.
relational database	A collection of data items organized as a set of formally-described tables from which data can be accessed or reassembled in many different ways without having to reorganize the database tables.
relay	OSI terminology for a device that connects two or more networks or network systems. A data link layer (Layer 2) relay is a bridge; a network layer (Layer 3) relay is a router.
router	Network layer device that determines the optimal path along which network traffic should be forwarded. Occasionally called a gateway (although this definition of gateway is becoming increasingly outdated).
routing table	Table stored in a router or some other internetworking device that keeps track of routes to particular network destinations and, in some cases, metrics associated with those routes.
RS-232	Popular communications interface that supports unbalanced circuits at signal speeds of up to 64 kbps. Also known as EIA/TIA-232.
RS-422	Essentially, a faster (up to 2 Mbps) balanced version of RS-232 capable of longer cable runs.
run-time	Period when an application or machine is actually being processed or is processing. As opposed to being in development or program mode. Functions or properties may only available in run-time.
segment	Section of a network that is bounded by bridges, routers, or switches.
serial transmission	Method of data transmission in which the bits of a data character are transmitted sequentially over a single channel.
server	Node or software program that provides services to clients.
session	Related set of communications transactions between two or more network devices.
shielded cable	Cable that has a layer of shielded insulation to reduce EMI.
signal-to-noise	The difference in amplitude between a baseband signal and the noise in a portion of the spectrum. Abbreviated as S/N (also SNR).
socket	Software structure operating as a communications end point within a network device.
spam	Term used to describe unsolicited e-mail or newsgroup posts, often in the form of commercial announcements.
spoofing	"1) Scheme used by routers to cause a host to treat an interface as if it were up and supporting a session in order to convince that host that the session still exists. 2) The act of a packet illegally claiming to be from an address from which it was not actually sent. Spoofing is designed to foil network security mechanisms such as filters and access lists. "
spooler	Application that manages requests or jobs submitted to it for execution. Spoolers process the submitted requests in an orderly fashion from a queue. A print spooler is a common example of a spooler.
star topology	LAN topology in which end points on a network are connected to a common central switch by point-to-point links.
string	A group of text characters. Generally any text, as opposed to numerical, data.
subnet address	Portion of an IP address that is specified as the subnetwork by the subnet mask.
subnet mask	32-bit address mask used in IP to indicate the bits of an IP address that are being used for the subnet address.
subnetwork	Networks arbitrarily segmented by a network administrator in order to provide a multilevel, hierarchical routing structure while shielding the subnetwork from the addressing complexity of attached networks. Sometimes called a subnet.
switch	Network device that filters, forwards, and floods frames based on the destination address of each frame.
Synchronous	In general, having identical period and phase or happening in the same time period. In computing, implies a time-coordinated set of signals or activities.
synchronous transmission	Term describing digital signals that are transmitted with precise clocking. Such signals have the same frequency, with individual characters encapsulated in control bits (called start bits and stop bits) that designate the beginning and end of each character.
tag	1) In networking, identification information, including a number plus other information. 2) In SCADA systems, an element of the real-time database, including the tagname, description, tag type, etc. 3) In PLC programming, it is sometimes synonymous with "symbol".
tagname	In SCADA systems, the unique identifying string of a database tag or element.
Telnet	Standard terminal emulation protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system.
terminal	Simple device at which data can be entered or retrieved from a network. A "dumb terminal" may have a monitor and a keyboard, but no processor or local disk drive.
terminal emulation	Network application in which a computer runs software that makes it appear to a remote