JAOMAD Glossary H:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Intro
H—Means "Hand"(Manually Initiated) when used in first alpha character position of ISA instrument function tag, means "High" in succeeding position [see ANSI/ISA S5.1-1984 (R1992)]; also: Hydraulic signal.
H1—Hunk 1; ISA SP50 (Foundation Fieldbus) standard for communications between sensors, actuators, and control devices; generally lower speed and lower cost than H2 or HSE.
H1 Field Device—In FOUNDATION Fieldbus technology, fieldbus device connected directly to H1 fieldbus; typically valves and transmitters.
H1 Repeater—In FOUNDATION Fieldbus technology, active, bus-powered or non-bus-powered device used to extend range over which signals can be correctly transmitted and received for a given medium; maximum of four Repeaters and/or active Couplers can be used between any two devices on an H1 fieldbus network.
H2— Hunk 2; ISA SP50 (Foundation Fieldbus) standard for more sophisticated "data highway" level communications between controlling devices, operator interfaces, etc. of distributed process control systems; generally much higher speed and higher cost than H1; completed but replaced by High Speed Ethernet (HSE).
H/PC—Handheld Personal Computer; runs on compact operating system, Windows CE, which was created to enable new categories of business and personal devices; using Windows CE , these devices can communicate, exchange information, connect to Internet, and synchronize with Windows-based computers through user interface that looks and feels like familiar Microsoft Windows standard.
H/W—Hardware.
HACCP—Hazard Analysis at Critical Control Point, see definition.
Hacking—In computers, computer communication; fooling around with computing functions to learn new or different functions and techniques; due to misuse in the news media, term has come to mean by some, to cause unauthorized access to other computers over public networks, see Cracking.
Hacktivism—Act of hacking into website or computer system to communicate politically or socially motivated message, as opposed to causing malicious harm.
Hairline Register—In composition of screen displays and printing, register within ±1/2 row of dots.
HAL—In computer programming, Hardware Abstraction Layer, see definition; also: Heuristic/Algorithmic; computer in the film "2001," which takes over command of the spaceship; some find significant that each of the letters in H-A-L coincidentally precede the letters I-B-M.
Half Bridge—In strain gauges, such as in force or pressure sensors, only two of four legs of Wheatstone Bridge configuration are active in development of a signal.
Half Duplex Transmission—“One way at a time” communication; both devices can transmit and receive data, but only one at a time.
Halftone—In electronic publishing and screen displays, reproduction of continuous-tone images, through screening process, which converts image into dots of various sizes and equal spacing between centers (as with conventional printing); also called Amplitude Modulated (AM) screening.
HALT—Highly Accelerated Life Test; typically rapid ramp-soak cycling of electronic equipment between the extremes of its temperature rating while operating over 2-3 days to quickly identify failures that would otherwise take years to surface (remove “infant mortalities); intention is if unit can make it through burn-in, it can make it to end of it's life with no failures.
Hamming Distance (HD) – In digital communication, measure for how secure protocol is against misinterpretation of packet with errors as some different legal packet; for example, HD=4 tells us that at least 4 bits has to be wrong, and still match checksum calculations in order to be mistaken as another valid packet.
Hand Set—This term applies to timers that are set manually after each operation; operator turns set pointer to required time interval, and during timing, the timer motor drives pointer back to zero.
Handheld PC—Palmtop computer that weighs less than one pound and runs specialized versions of popular applications; Microsoft coined the term for its Windows CE operating system, which is an abbreviated version of Windows 95/98.
Handshaking—Exchange of predetermined signals between two devices to establish a connection; usually part of a communications protocol.
Hang—Computer freeze or lock-up; see ABEND.
HAP—Hazardous Air Pollutant(s); a consideration in EPA (U.S.) regulations.
Haptic Interface—Communicating with computer via some tactile method; haptic devices sense some form of finger, hand, head or body movement.
Hard Copy—Output in permanent (paper) form, usually through printer or chart recorder, as compared with disk or display terminal.
Hard Disk, Hard Drive—In computers, platter-shaped disk(s) which rotate(s) very fast and which has greater storage capability and quicker access than floppy disk, usually sealed and non-removable; unlike floppy disks, disk and drive are inseparable, so proper term is Hard Drive; also: device that allows users to delete vast quantities of data with simple mnemonic commands.J
Hardware—Electrical, mechanical, and electromechanical equipment and parts associated with a system, as compared with Software, Firmware, Wetware and Vaporware; also: collective term for any computer-related object that can be kicked or battered, but will stop working when your favorite beverage is spilled on it.J
Hardware Abstraction Layer (HAL) —In computer programming, source code for development allows real-time extensions to the HAL conformed closely with standard interfaces of the host operating system; operations between real-time objects and processor are based on fixed time slice; translation layer in Windows NT that resides between kernel & I/O system and the hardware itself to be able to port NT to another platform by designing a new HAL layer for it (parts of the kernel may have to be optimized).
Hardware Key—Copy protection device supplied with software that plugs into a port (parallel, serial, USB, etc.) on a PC; its software sends code to that port, and key responds by reading out its serial number, which verifies its presence to program; designed to hinder software duplication, because each copy of program is tied to unique number, which is difficult to obtain, and key has to be programmed with that number; often called a “dongle”
HART—Highway Addressable Remote Transducer; open "smart" field instrumentation protocol developed by Rosemount® which has been adapted by several other companies, creating a "de facto" standard "fieldbus;" not considered a true fieldbus by some, it imposes Bell 202 FSK, 1200 bps digital signal on twisted pair of wires carrying 4-20mA input.
HASL—Hot Air Solder Level.
Hazard Analysis at Critical Control Point (HACCP) —Preventative control system based on food safety and widely applied in today's industry, especially with regard to quality; derived from engineering system, "failure mode and effect analysis" which looks at a product, all its components and manufacturing stages and asks what can go wrong; developed as food safety tool in 1960's by Pillsbury Company, United States Army Laboratories and NASA, its original purpose was to ensure that food for astronauts would be free from pathogens and toxins; Pillsbury presented it to American National Conference for Food Protection in 1971 and has since been modified and developed by the food industry.
Hazardous Classifications—NEC ratings for hazardous atmospheres:
Division 1—Continuous hazard (>1000hrs/yr), Zone 0 for gasses, Zone Z (10) for dusts; & Intermittent hazard (10-1000hrs/yr), Zone 1 for gasses, Zone Z (10) for dusts.
Division 2—Hazard under abnormal conditions (0.1-10hrs/yr); Zone 2 for gases, Zone Y (11) for dusts.
Class I—Areas in which flammable gases or vapors may be present in air in sufficient quantities to be explosive.
Group A—Atmospheres containing acetylene.
Group B—Atmospheres such as butadiene, ethylene oxide, propylene oxide, acrolein, or hydrogen (or gases, vapors equivalent in hazard).
Group C—Atmospheres such as cyclopropane, ethyl ether, ethylene, or gases, vapors equivalent in hazard.
Group D—Atmospheres such as acetone, alcohol, ammonia, benzene, benzol, butane, gasoline, hexane, lacquer solvent vapors, naptha, natural gas, propane, or gases, vapors equivalent in hazardous.
Class II—Areas made hazardous by presence of combustible dust.
Group E1—Atmospheres containing combustible metal dusts, regardless of resistivity.
Group E2—Atmospheres containing combustible dust of similarly hazardous characteristics having resistivity less than 100kW-cm.
Group E3—Atmospheres containing combustible electrically conductive dusts.
Group F1—Atmospheres containing combustible carbon black, charcoal, or coke dusts having more than 8% total volatile material.
Group F2—Atmospheres containing combustible dusts having an explosion hazard with resistivity <100W-cm & > 1x108W-cm.
Group G1—Atmospheres containing combustible dust having resistivity < 100kW-cm.
Group G2—Atmospheres containing combustible electrically nonconductive dusts.
Hazardous Location—Area where possibility of explosion and fire is created by presence of flammable gasses, vapors, dusts, fibers, or flyings.
Hazardous Waste—Under Resource Conservation and Recovery Act (U.S.), any solid, liquid, gas, or combination of wastes which, because of its chemical, physical, or infectious characteristics, may pose hazard when managed improperly.
HAZOP—HAZard & OPerability studies.
HAZWOPER—HAZardous Waste OPerations and Emergency Response.
HBT-IC—Heterojunction Bipolar Transducer – Integrated Circuit; have low base imput impedance s are less effected by noise components than FETs.
HCF—(Hart Communication Foundation); formed in 1993 as an independent, non profit organization specifically to carry on work of HART user group to provide overall coordination and support for application of HART technology.
HCFC—HydroChloroFluoroCarbon, a consideration in EPA (U.S.) regulations; any of several substances used as alternatives to CFCs, but also thought to cause depletion of Earth's protective ozone layer.
HCI—Human-Computer Interface
HCM—Human Capital Management.
HCS—Hybrid Control System; see definition.
HD—Harmonization Document, relating to international standards; also: High Density, such as with memory disks; also: High Definition, such as higher number of scan lines on cathode ray tube; also: Hard Drive or Hard Disk, used as memory media in computers; also: Hamming Distance, a measure of protocol integrity, see definition.
HDC—Highly Distributed Control.
HDCD—High Definition Compatible Digital; for video data.
HDCD-ROM—High Density Compact Disk Read Only Memory; for digital data storage.
HDL—Hardware Description Language.
HDLC—High-level Data Link Control; international standard communication bit-oriented protocol defined by CCITT for ISO, and used in Open Systems Interconnection (OSI).
HDR—High Data Rate; usually in context of digitizing video information.
HDTV—High Definition TeleVision; has pixel resolution of 1920x1080.
HDVD—High Definition Volumetric Display; enables one to take images directly from PC screen through special device, projecting them in 3-D onto thin air like a holographic image.
HDX—Half DupleX; mode of communication in which two directional data will flow only one direction at a time (2-wire).
He/Ne—Helium-Neon red laser.
Head End—Passive component in broadband transmission network that translates one range of frequencies (transmit) to different frequency band (receive); allows devices on single cable network to send and receive signals without interference.
Head Loss—Loss of pressure in flow system measured using a length parameter, such as "inches of water," or "inches of mercury;" presumed condition of some managers in a crisis J.
Head Margin—In typographical composition of screen displays and printing, unused space above first line on a page.
Head Mounted Display (HMD)—Display system built and worn like goggles that gives illusion of floating monitor in front of user's face; critical component of body-worn computer (wearable computer); single-eye units are used to display hands-free instructional material, and dual-eye, or stereoscopic, units are used for virtual reality applications; can be used while touring plant to make modifications or adjustments to process.
Head Pressure—Pressure in terms of the height of fluid.
Header—In digital transmission, control information added to beginning of a message; contains destination address, source address, and message number.
Headline, "Head"—In typographical composition of screen displays and printing, display type, usually at top of screen or document to identify topic.
Heartbeat—Signal Quality Error (SQE) in CSMA/CD communication media access method, test between transceiver/MAU and DTE to ensure collision detection circuit in the transceiver/MAU is working.
Heat—Thermal energy, expressed in units of calories or BTUs.
Heat Sink—In thermodynamics, body which can absorb thermal energy; in mechanical design, finned piece of metal used to dissipate heat from components mounted on it.
Heat Transfer—Process of thermal energy flowing from body of low energy; means of transfer include: conduction where two bodies contact, convection where the two bodies contact different phases (such as solid and gas), and radiation where the bodies emit infrared radiation.
Help—computer feature that assists in generating more questions; when used correctly, users navigate through series of Help screens to end up where they started, without learning anything.J
Hertz (Hz)—Unit of frequency defined as one cycle per second.
Heuristic—Describes learning, discovery, or problem-solving approach based upon commonsense rules (rules of thumb) as well as trial and error, as compared with comprehensive theory found in algorithms, using mathematically provable procedures; heuristic programs are characterized by being self-learning, which get better through experience, arriving at a good result if not always best result; often used in expert systems.
HEX—HEXadecimal; refers to base 16 number system using characters 0 through 9 and A through F to represent values; often used in machine language programs.
HF—Latent Heat of Fusion.
HGED—High-Gain Emissive Display; flat LCD-like panel containing color phosphors similar to those of CRTs, but modified to operate at extremely low voltage (under 100), activated by matrix grid instead of beam-steered, high voltage electron gun; unlike LCDs, matrix needs no transistors to address pixels, phosphors are instead excited by electrons guided to grid by patented process by Telegren, Inc.; less than one tenth of LCD cost and no viewing angle restrictions; has brightness, color palette, resolution, refresh rates needed for high-definition video, without concern of X-ray emissions of near-field viewing.
HIDS—Host Intrusion Detection Sensor; see definition.
Hierarchical—Approach used in many technologies, including process control, machine vision, system networks, databases, sequence of video screen views, and planning, where actions, scope of work, etc. is arranged in hierarchies that establish priorities and appropriate routings.
High Level Language—Problem oriented programming language in which each instruction may be equivalent to several machine code instructions.
High Pass Filter—In digital signal processing (DSP), filter that attenuates low frequencies and passes high frequencies.
High-level Data Link Control—(HCLD) international standard communication protocol defined by ISO.
High Speed Ethernet (HSE)—In FOUNDATION Fieldbus technology, Fieldbus Foundation's backbone network running at 100 Mbit/second.
HiNIL—High Noise Immunity Logic.
HiPPI High Performance Parallel Interface; ANSI-standard high-speed communications channel that uses a 32-bit or 64-bit cable and transmits at 100 or 200 Mbytes/sec; used as point-to-point supercomputer channel or, with crosspoint switch, as high-speed LAN.
HIPPS—High Integrity Pressure Protection System.
HIS—Human resources Information System, computer database of manpower scheduling used in EIS: also: HDL (Hardware Description Language) Interactive Simulation.
HIST—Host Interoperability Support Test; see definition.
Histogram—Bar graph to show frequency distribution of various characteristics in statistical analysis (in SPC).
Historical Data—In process control, operating data saved within specific device, equipment or system; see Archival.
Hit—Internet term for successful access to file on Web page.
HJBT—HetroJunction Bipolar Transistor.
H/L—High/Low; alarm thresholds.
HMD—Head Mounted Display; see definition.
HMI—Human Machine Interface, see definition.
Hold Station—Usually circuit card(s) with capacitive elements to hold electrical charges representing values calculated by controllers, until some multiplexing operation sends those signals to the field; output signal conditioning circuitry may still be called this by some.
Holding Time—Length of time communication channel is in use for each transmission.
Home Page—First HTML page users generally see upon reaching Internet World Wide Web site of individual or corporation.
Honeypot—Internet-attached server that acts as decoy for cyber security, luring in potential hackers in order to study their activities and monitor how they are able to break into a system; designed to mimic systems that an intruder would like to break into but limit the intruder from having access to an entire network.
HOOPS—Hierarchical Object-Oriented Picture System; emerging standard in 3D graphics.
Horsepower—Unit of ability to do work; equivalent to movement of 33,000 pounds moving through one foot in one minute.
Host (Computer)—In process control, primary or controlling computer in multiple part system, providing primary services such as computation, database access, special programs, generating commands, or programming languages; in some earlier DCSs the system was configured by programming the host, then downloaded over the network to each controller file; the term "host" implies that the computer is required for the complete performance of the system; see Guest.
Host (System)—Term used in context of control system that supports a FOUNDATION Fieldbus network.
Host Interoperability Support Test (HIST)—Procedures that shows host system made by controls manufacturers incorporating features defined by Fieldbus Foundation is in fact capable of supporting interoperability, including: device tag assignment, device address assignment, configuration of link master devices, block tag configuration, block instantiation, standard blocks, enhanced blocks, custom blocks, function block linkage configuration, alert configuration, alert handling, trend configuration, trend handling, device description services, device description method execution, device description menu handling, device description edit displays handling and capabilities files; host can be HMI, DCS, PC, recorder, alarm display panel, or system with combination of functionality.
Host Intrusion Detection Sensor (HIDS)—Cyber security software that loads on host computer system; identifies attacks using signatures or behavior analysis and attempts to prevent the attack and is generally an active defense that combines attack identification and response.
Hot Backup—Backing up database that is in active use as in controller which turned on and tracks inputs, outputs, control actions, sequence steps, etc. so that switch-over is essentially transparent to process; see Hot-standby; compare Cold Backup, Warm Backup.
Hot Junction—That thermocouple junction used to measure an unknown temperature (measuring junction) for comparison to a known.
Hot-standby—In distributed control systems, usually means duplicate (redundant) device such as controller, which carries identical information and can be functionally switched into replacement service with essentially no interruption of those functions; see Hot Backup; compare Warm Backup, Cold Backup.
Hot-swapping—Ability to remove and replace electronics board or device without removing power from equipment in which it resides; also: hardware & software protocol defined by PCMCIA whereby PC cards can be removed and inserted into sockets without powering-down or rebooting PC.
HP—Horsepower.
HPC— High-Performance Computing; also: Handheld PC, see definition.
HPC™—High Performance Controller; microcontroller chip by National Semiconductor.
HPGL—Hewlett Packard Graphic Language.
HPI—Human Process Interface; also: Hydrocarbon Processing Industry.
HP-IB—Hewlett-Packard Interface Bus; IEEE488 standard; parallel, multiport, 300Kbs to 1Mbs, 15-28 stations on up to 50 feet; originally developed by Hewlett-Packard for laboratory instrumentation and later called GPIP.
HPLC—High Pressure Liquid Chromatography.
HP-UX—Hewlett-Packard UniX; version of UNIX software standard initially developed by Hewlett Packard and now are Open Group UNIX 95 branded products; see UNIX.
HPV—High Performance Vane.
HRF—Hazard Reduction Factor; inverse of PFD, which are chances of control system failure in energized mode.
HS—Hand Station to provide direct process control signal to final element; also: Hydraulic Supply.
HSB—Hot StandBy; see definition.
HSE—High Speed Ethernet, see definition; also: Health, Safety & Environment requirements of plant.
HSE Field Device—In FOUNDATION Fieldbus technology, fieldbus device connected directly to High Speed Ethernet (HSE) fieldbus; typically HSE Linking Devices, HSE Field Devices running Function Blocks (FBs), and Host Computers.
HSE Linking Device—In FOUNDATION Fieldbus technology, device used to interconnect H1 fieldbus Segments to High Speed Ethernet (HSE) to create a larger network.
HSE Switch—In FOUNDATION Fieldbus technology, standard Ethernet equipment used to interconnect multiple High Speed Ethernet (HSE) devices such as HSE Linking Devices and HSE Field Devices to form a larger HSE network.
HSI—Human System Interface.
HSLN—High Speed Local Network.
HSM—Hierarchial Storage Management; digital memory and data backup system.
HSV—Hue, Saturation, Value (or brilliance, or luminance); color space used in some graphic programs for screen displays.
HSWA—Hazardous and Solid Waste Amendments; 1984 amendments to Resource Conservation and Recovery Act (U.S.) establishing land disposal and underground storage tank regulations for hazardous materials.
HTE—High Temperature Elongation.
HTG—Hydrostatic Tank Gauging.
HTL—High Threshold Logic.
HTML—HyperText Markup Language; basic computer authoring programming & content language for internet/intranet/extranet web sites; standard of World Wide Web Consortium (W3C) that is an ASCII file that describes page layout to publish documents using both text and two dimensional graphics.
HTTP—HyperText Transport Protocol; Hypertext Transfer Protocol; Internet computer communication encoding standard which is platform-neutral for exchange of multimedia documents across Web; digital communication protocol responsible for transport of communication between server and browser; usually HTTP is based on technical internet protocol (IP).
Hub—In digital communications, wiring concentrator called dumb hub; passive hubs extend network to longer distances, using connection of several star topologies, sending all messages to all stations, thereby improving where stations can be located; active hubs act as repeaters, sometimes called multiport repeaters, either amplifying the signals (noise & all) or regenerate signals (replicate signals without the noise); compare Smart Hub.
Hue—In video screen displays and printing, main attribute of given color which distinguishes it from other colors.
Human Machine Interface (HMI)—Has become the most popular of the many terms referring to method of displaying machine & process status, alarms, messages, and diagnostics, often graphical display on a personal computer, providing operator feedback.
HURD—To be foundation of whole GNU system; built on top of Mach 3.0 kernel, a free message-passing kernel developed by Carnegie Mellon University (CMU); Mach's virtual memory management and message-passing facilities are extensively used by the Hurd; GNU C Library will provide UNIX system call interface, and will call the Hurd for needed services it can't provide itself; one goal is to establish a framework for shared development and maintenance; The Hurd is like GNU Emacs in that it will allow a broad range of users to create and share useful projects without knowing much about the internal workings of the system -- projects that might never have been attempted without freely available source, a well-designed interface, and a multi-server-based design; see GNU, EMACS.
HV—Latent of Vaporization.
HVAC—Heating, Ventilating, & Air Conditioning; also: High Voltage Alternating Current; also: High Volume Air Conditioning.
HVDC—High-Voltage Direct Current.
HVLC—High Volume, Low Concentration, usually in reference to pollutant measurement for EPA (U.S.) regulations.
HWT—Hot Water Temperature.
Hybrid Control System (HCS)—Originally meant control system which includes both "classic" distributed control (DCS) and programmable control (PLC) components connected onto same network for processes or operations that need benefits of each system; now considered process control system that is much more than merely “PLC with PC,” but with characteristics of “traditional” Distributed Control System (DCS); generally uses relatively open technology of TCP/IP communications network between peer-to-peer controllers and a PC workstation, but with sophisticated process control strategies and operating graphics created through easy familiar object-oriented configuration tools, system-wide diagnostics, system-wide alarm handling techniques, etc.; actual definition muddied by various supplier marketing efforts to define their system, so depends upon who you ask: some define them by the industries served (see Hybrid Industries), some by the ability to have both discrete and analog functions, some by the ability to to perform flexible sequencing functions for batch control, and some by the architecture of the system itself as a PLC-like system with very strong DCS characteristics, providing the benefits of both without the disadvantages of either, designed as above; some now beginning to use the term Programmable Automation Controller (PAC) for the function.
Hybrid Industries—Defined by ARC Advisory Group as those which are strongly batch-related, such as food & beverage, pharmaceutical, and specialty chemicals.
Hybrid System—Phone system that combines many features of Key phone system and PBX (private branch exchange) phone system; not every incoming line appears on every phone, as in most Key systems, but the hybrid system can accommodate both Key and PBX phones; see Key System.
Hydrophillic—Water receptive.
Hydrophobic—Water repellent.
Hygrometer—Instrument used for determining relative humidity.
Hypercard—Programming environment which organizes information into what appears functionally to the user as stacks of index cards; theses stacks can then be manipulated and resorted to create new applications.
Hyperlink—In networked computers, path between two documents which allows user to point-and-click on specific words in one document on screen to move to some other document, wherever it physically is located.
Hypermedia—Hypertext function expanded so that documents contain links not only to other pieces of text, but also to other forms of media—sounds, images, and video; images themselves can be selected to link to sounds or documents, etc.
Hypertext—Basically same as regular digital communication text - it can be stored, read, searched, or edited - but is also has connections (links) within that text to other documents, for example while viewing word or phrase in one document, user can access and retrieve any other document using that word or phrase.
Hysteresis, Switching—Principle associated with sensors, such that operate point is not at same level as release point; in solid state sensors, it is accomplished electrically; in mechanical switches, it results from storing of potential energy before transition occurs; also known as differential, and is usually expressed as percentage of operate point (e.g. 3-15%).
Hysteresis—Difference in signal when point to be measured is first approached with increasing values, and then with decreasing values usually expressed in percent of full scale during any one calibration cycle; lagging in response of a unit of a system behind an increase or a decrease in strength of a signal; property of physical systems that do not instantly follow the forces applied to them but react slowly, or do not return completely to their original state.
Hz—Hertz; a unit of frequency equal to one cycle per second.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Intro