Glossary

A

accumulator - a computer circuit or register that receives, totals and stores weighing data.

accuracy - precision in weight measurement, as expressed in terms of the percentage of error between measured weight and actual weight. 

analog to digital (A/D) - Conversion of analog voltage levels to digital values, e.g. a load cell sends analog data through an A/D converter to an indicator that reads digital values

ambient conditions - the physical conditions of the medium around the load cell, including humidity, pressure and temperature.

ampere - one unit of electrical current intensity.  It is measured as 6.24 x 1018 electrons passing a point in one second. Can be abbreviated as amp.

analog - data represented by a continuous wave of values instead of discrete steps

approved - designation of equipment that has been deemed acceptable by an authority with jurisdiction over the area in which the equipment will be used.

American Standard Code for Information Interchange (ASCII) - Seven-bit plus parity code established by the American National Standards Institute (ANSI) to achieve compatibility between data services. Pronounced "askee".

automatic zero maintenance (AZM) - electronic feature that compensates to provide "true zero" on a digital scale under varying minor conditions, like indicator or load cell drift or debris on a scale platform

average piece weight (APW) - the total weight of It is used by counting scales to determine number of pieces according to weight total. 

B

baud rate - the rate at which information is transferred in a communication channel. In the serial port context, "9600 baud" means that the serial port is capable of transferring a maximum of 9,600 bits per second.

bi-directional - the flow of data in either direction on a wire between pieces of equipment where both can receive and transmit data.

bit - The smallest unit of information in a binary system, consisting of a “0” or a “1” (abbreviation of Binary Digit).

board of governors - the body of officials from the National Conference on Weights and Measures that sets National Type Evaluation Program (NTEP) policy and has final say in disputes.

C

calibration - the process of checking for accuracy and errors in measurement by comparing load cell output against standard test loads, specifically, calibration weights

calibration error - the difference between the weight shown on the display, and the item's true mass as measured by a calibrated instrument.

cantilever beam - A beam-type load cell with load-sensing elements mounted on the inside perimeter of a machined-out center.

capacity - the maximum weight amount that a scale or load cell can weigh accurately

CC (NTEP Certificate of Conformance) - Certification by the National Type Evaluation Program that a weighing device meets all applicable requirements of Handbook 44.

checkweigher - a scale used to verify predetermined weight within prescribed limits.

class III scales - class of scales used in commercial weighing that are not otherwise specified. These include grain test scales, retail precious metals and semiprecious gem weighing, animal scales, postal scales, and scales used to determine laundry charges.

class IIIL scales - vehicle, axle-load, livestock, railway track scales, crane and hopper (other than grain hopper) scales.

compensation - the use of supplementary devices, materials or processes to minimize known sources of error.

compression - a force applied to a strain gauge that compresses the gauge wires and increases their cross-sectional area, thereby decreasing gauge resistance. 

concentrated load capacity (CLC) - maximum load, as prescribed by the manufacturer, that can be placed anywhere on the platform of a vehicle, axle-load or livestock scale using the prescribed test pattern (an area at least 4 feet long and as wide as the scale platform).

cornerload - an instrument's ability to deliver the reliable and consistent weight readings for a given object on the corners of the weighing pan.

cornerload error - variations in weight measurements when an object is moved to corner positions on the weighing pan.

count - the smallest weight increment displayed.

creep - change in load cell output occurring with time, while under load, and with all environmental conditions and other variables remaining constant. Creep is usually measured with Rated Load applied and expressed as a percent of Rated Output over a specific period of time.

creep recovery - change in no-load output occurring with time, after removal of a load which has been applied for a specific period of time; usually measured over a specified time period immediately following removal of rated load and expressed as a percent of rated output.

D

dead load - the fixed force of load-supporting structures of the scale, the value of which needs to be permanently balanced or cancelled out in the weight or measuring system.

digit - the smallest increment of weight an indicator can resolve.

digital - a system where data is represented by discrete signals rather than continuous waves of variable (analog) values.

digital averaging - the feature of a digital indicator that allows it to compensate for erratic readings by taking several readings and averaging them together before sending the signal to the display. 

digital filtering - electronic stabilization of the indicator's readout when compensating for moving weights, like animals. Digital filtering changes how sensitive a scale is to variations in movement. The more digital filtering applied, the more accurate display reading, but a longer settling time is required.

division - the smallest increment indicated (displayed) by a scale. The amount of divisions a scale has can be determined by dividing its capacity by its readability (the smallest increment a scale can display. For example, a 2,000 gram capacity scale with increments of .1 grams would have the following number of divisions: 2,000/.1 = 20,000 divisions. The more divisions a scale has, the better the quality of its weighing sensor, the more precise the scale is.

drift - continuous upward or downward change in weight shown on the digital display. This could be due to temperature, static electricity or RFI (radio frequency interference).

E

electrical noise - outside sources of currents or voltages that interfere with expected electrical quantities. Sources may include lightning, radio transmitters, welding equipment,  or electrical switching equipment.

environmentally protected - referring to load cells that are protected from normal environmental factors both indoor and outdoor. They should not be submersed or washed down.

excitation - the electrical current applied to the input terminals of the load cell.

excitation trim - method of adjusting the excitation voltage to each individual load cell in order to match load cell outputs in a multicell system. 

explosion proof enclosure - an enclosure that is capable of withstanding an explosion of any gas or vapor. It is also safeguarded against the ignition of the gas surrounding the enclosure. 

F

filtering cutout sensitivity - specifies the amount of consecutive readings that must fall outside the filter threshold before filtering is suspended. 

filtering threshold - a set limit in display divisions; filtering is suspended when a certain number of readings fall outside this limit.

flexures - thin steel or plastic plates that restrict scale movement and reduce friction.

full duplex - simultaneous bi-directional data transmission.

G

gated power supply - power supplied to device only when signal magnitude is within its specified limits.

grads - the number of full-scale graduations.

H

half duplex - bi-directional data transmission that is not simultaneous.

handbook 44 - (Complete title: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices); a comprehensive set of requirements for weighing scales to be used in commerce. It is developed and updated by the National Conference on Weights and Measures (NCWM). 

handshaking - the exchange of signals between two devices for data exchange.

hazardous location - a location where the presence of flammable gases or vapors, flammable liquids, combustible dust or fibers may present a fire or explosion risk.

hermetically sealed - load cells with a welded cover to protect the strain gauge cavity. Some load cells may have an extra protective layer at the cable entry. These load cells are protected against harsh chemical or washdown environments.

hysteresis - the maximum difference between output readings for the same load. 

I

ingress protection (IP) rating - a rating system that defines the progressive levels of protection a product or electrical enclosure can provide against the ingress of solid objects and liquids. It consists of the letters IP followed by two digits, the first indicating a level of intrusion protection, and the second indicating a level of moisture protection. 

initial zero range - the amount of applied weight, calculated as a percentage of max capacity, that will automatically zero when the indicator is powered on. 

instability - the displayed number shows a string of random variations, rather than a steady progression.

interface - a device, circuit or cable that allows communication between two units.

International Organization of Legal Metrology (OIML) - Treaty organization that recommends technical requirements for weighing and measuring equipment before it can be sold or distributed.

intrinsic safety barrier - a network that is designed to limit the voltage and current to the protected circuit in a hazardous location.

intrinsically safe circuit - a circuit that has demonstrated in testing that it will not ignite a mixture of flammable or combustible material in the air, whether by a spark or thermal effect.

J

junction box - an enclosure that joins different cable or wiring. It contains terminals for connecting enclosed conductors.

L

light emitting diode (LED) - a semiconductor light source that emits visible light when voltage is applied.

linearity - the ability of a scale to deliver identical sensitivity throughout its weighing capacity.

linearity calibration - a method of minimizing discrepancy between the actual and displayed weights throughout a scale's weighing range. It uses calibration points at bottom, mid, and top range.

linearity test - a test that measures a scale's ability to have identical sensitivity throughout its weighing range.

liquid crystal display (LCD) - a flat electronic display that uses two transparent electrodes to apply a current through a thin layer of liquid crystal, which causes the crystal to transmit visible polarized light.

live load - any load that is placed on the scale platform and is currently being measured.

load - a weight or force that is applied to the load cell.

load cell - a device, usually made of metal, which produces an electrical output signal that is proportional to the weight or force applied to it. Different load cells are ideal for different applications. Types of load cells include platform, beam, S-beam, compression and tension.

M

manual zero range - the amount of applied weight, as a percentage of max capacity, at which point the indicator will allow the user to manually zero the weight. (Anything above this weight will be tared).

minimum dead load - a requirement that the dead load applied to each cell must be greater than or equal to the minimum dead load specified by the load cell manufacturer. In NTEP load cells, the minimum dead load is specified.

minimum weight - the minimum piece weight required in counting mode. Usually used in reference to counting scales.

motion detection - a circuit in an indicator that senses when the displayed weight data is unstable. When instability is detected functions like data output, auto-zero, auto-tare or zero tracking may be inhibited.

N

National Conference on Weights and Measures (NCWM) - an association of state and local officials, consisting of both federal and industry representatives that adopt uniform laws and regulations (e.g., NIST Handbook 44).

National Electrical Manufacturers Association (NEMA) - an association of electrical equipment manufacturers that develops standards for the electrical manufacturing industry.

National Institute for Standards and Technology (NIST) - an agency of the federal government to which all precision measurements may be traced.

National Type Evaluation Program (NTEP) - a program coordinated by the National Conference On Weights & Measures, NIST, state-level weights and measures officials, and the private sector, to determine conformance of weighing equipment with H-44 provisions.

negative display - the extent of the range an indicator can display a negative value before showing an error code.

negative value - the tared value displayed as a negative number after an item is removed from the scale.

noise filter - an electronic filtering system that compensates for general variations that may affect the scale.

nominal load capacity - the designed normal maximum load cell capacity, as specified, on which output load cell sensitivity is based. 

O

Office of Weights and Measures (OWM) - Office of Weights and Measures at NIST.

ohm - the unit of electrical resistance. The resistance through which a current of one ampere will flow when one volt is applied.

OIML (International Organization of Legal Metrology) - Treaty organization that recommends technical requirements for weighing and measuring equipment before it can be sold or distributed.

original equipment manufacturer (OEM) - a company that makes products from components bought from an original manufacturer or several other manufacturers.

output - the electric signal produced by a load cell. 

overload range - weight allowance that is out of the set calibrated range. Adds tolerance to the calibrated max. capacity without having to recalibrate. For example, if your scale has a max. capacity of 1,000 lbs with a division of 1 and you set the overload range to 60, you can add a 1,060 lb load to the scale without it displaying an error code. 

overload rating, safe - the maximum load that can be applied to the scale without a permanent effect on its performance characteristics. Overload is expressed as a percent of rated capacity.

overload rating, ultimate - the maximum load that can be applied to the scale before causing structural failure. Overload is expressed as a percent of rated capacity.

P

parity - used in error checking, whereby the data of a given character receives an extra bit to establish either an even or odd number of bits.

port - the point or physical terminal at which electrical data signals may be introduced to or extracted from a circuit, device, or system.

R

radio frequency interference (RFI) - external radio frequency energy large enough to that it might affect the operation of electrical components of the scale.

random-access memory (RAM) - data stored in the computer's memory that can be accessed in any order, also known as a read/write memory.

readability - smallest division an indicator can display.

read-only memory (ROM) - data or instructions that are permanently stored in the computer's memory for use by the machine or reference for the user. The stored information cannot be removed or added to by the user.

repeatability -  the ability of a scale or load cell to give consistent performance or results under repeated loadings in identical conditions.

RS-232 - a method of data communication used to transfer data between digital devices. Voltage-based.

RS-422 - a method of data communication that uses balanced or differential signaling. It is unidirectional/non-reversible.

RS-485 - a method of data communication that is effective over long distances and in electrically noisy environments. It may utilize multiple receivers. Ideal for industrial environments.

S

scale - a device consisting of, at a minimum, a load cell, indicator, and usually a platform, that is used for weighing, comparing or counting an object or material.

serial transmission - sequential transmission of data and information on a single channel.

shear beam - a bending beam load cell, in which the strain gauges are mounted on a spring element that compresses under a load and recovers when the load is removed. 

shift test - a test intended to verify the accuracy of a scale or the proper function of the load cells using off-center loading.

signal - the actual output of the load cell, where the analog signal is converted to digital. 

span - often used interchangeably with range, is the difference between the highest and lowest values.

stabilization period - the time it takes the scale to give an accurate weight within tolerable parameters.

standstill range - indicates how far over or under the actual weight a scale can fluctuate before being determined stable.

standstill time - the time required for a scale to be considered stable (also see stabilization time)

strain gauge - a device that detects the amount of strain a force produces on the load cell. It consists of embedded wires that compress or stretch, changing their resistance. Several strain gauges make up a load cell.

T

tare - the allowance or reduction from gross weight of the weight of an empty container or vehicle in order to return the scale to zero for additional object or material weighing.

tolerance - the amount of error that is allowed in a displayed value. It is usually expressed as a percent of actual weight value, plus or minus so many units of measurement.

trim - fine tuning of load cell outputs in a multicell system.

U

unit - the designated measurement unit that is to be represented. For example, ounce, kilogram, gram, lb, etc.

V

volt - a unit of voltage or electrical potential difference

voltage - the electrical potential difference between two points that form a closed circuit through which a current may flow.

W

watertight - an enclosure that is designed and constructed to prevent the intrusion of water under specified test conditions.

weatherproof - referring to an enclosure that is designed and constructed so that the exposure to specified weather conditions will not interfere with the normal operation of the equipment contained within. 

weight - the amount of gravitational pull by which an object is attracted toward the center of the earth.

Z

zero balance - the output signal of the load cell with no load applied.

zero function - a feature of the indicator that allows it to display a zero value for taring weight by pressing the tare key.

zero return - the difference in the stabilized zero balance before load application and after removal of the load.

zero stability - the degree to which the load cell maintains its zero balance with all else constant. 

zero tracking range - a subset to manual zero range; the ability to manually zero a scale within a set division even without a stabilized weight on the display.

zero tracking time - a subset to zero tracking range; the time it takes for a scale to fall within the zero tracking range tolerance and still allow manual zeroing. 

Reference: scalesu.com