Glossary of Terms
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A/D – Analog-to-digital
A/D Channel List Start – Signal used to start the A/D acquisition of channels in the channel list. The triggering edge of this signal (falling edge) enables the ADC Conversion Start signals.
A/D Conversion – The process of converting a single analog input to a digital value.
A/D Conversion Start – Signal used to start the conversion process of an analog input to a digital value. The source of this signal can be either an internal ADC synchronous clock or an external asynchronous signal. This signal causes the stepping in the Channel List.
AC (Alternating Current) – Electric current that varies in amplitude and direction. The usual waveform of ac is a sine wave, but can be triangular, or square.
Accelerometer – A device that measures proper acceleration. Proper acceleration measured by an accelerometer is not necessarily the coordinate acceleration, instead is the acceleration associated with the phenomenon of weight experienced by any test mass at rest in the frame of reference of the accelerometer device. Simply put, it will measure acceleration forces, that may be static (constant force of gravity) or dynamic (moving or vibrating the accelerometer).
Accuracy – A measure of the degree to which a data acquisition system is able to accurately detect and record the exact values of physical phenomena. It is usually expressed as a percentage of the full scale value of the measured phenomenon, and is a measure of how closely the acquired value matches the actual value of the phenomenon being measured. Accuracy is typically expressed as either absolute accuracy or relative accuracy. Absolute accuracy is the difference between the acquired value and the actual value of the phenomenon being measured, while relative accuracy is the difference between the acquired value and the full-scale value of the phenomenon being measured.
ADC (Analog-to-Digital Converter) – (a.k.a. simply an “A/D”) An electrical circuit that converts analog voltage into a binary number. A/D converters perform the measurements in all data acquisition systems; converts a continuous quantity to a discrete time digital representation. It may also provide an isolated measurement. The reverse operation is called a DAC (digital to analog converter). The electronic device converts an analog input (voltage or current) to a digital number proportional to the magnitude of the analog signal.
Aerospace – The process of gathering data from sensors, instruments, and other sources from aircraft and spacecraft. This data is then used to analyze and monitor the performance and status of aircraft and spacecraft. Aerospace data acquisition systems typically use sensors and instruments to measure and collect data about temperature, pressure, speed, acceleration, engine performance, and other parameters. Data is then processed and analyzed to provide insights into the performance of the aircraft or spacecraft.
Alias – A false lower frequency image of a high-frequency component that appears in sampled data acquired at too low a sampling rate.
Alumel – A brand name for a magnetic nickel alloy containing small amounts of manganese, aluminum, and silicon. Used in thermocouples and thermocouple extension wire.
Ampere (A) – SI unit of electric current.
Amplifier – A device for increasing the power of a signal by taking power from a power supply and controlling the output to match the input signal shape but with a larger amplitude.
Amplitude – The size or magnitude of a signal.
Analog Domain – The range of physical signals that are measured and/or manipulated by a data acquisition system. These signals can include electrical, mechanical, environmental, and/or chemical signals. The analog domain is the range of raw signals that are measured before they are converted to digital form, and is typically measured in terms of voltage, current, and/or temperature. The analog domain is used to capture and record real-world signals, then process, analyze, and store them for further use.
Analog Input – An analog input is an infinitely variable signal. In most data acquisition systems this signal is connected to an input amplifier and then to an A/D converter.
Analog Output – A waveform or control signal generated as a continuous function of the measured parameter.
Analog Trigger – A trigger that occurs at a user-selected point on an incoming analog signal. Triggering can be set to occur at a specific level on either an increasing or a decreasing signal (positive or negative slope).
Angle – In data acquisition, an angle is an angular measurement of a particular object or event in relation to an origin or reference point. Angles are typically measured in degrees, radians, or gradians, and can describe the direction of a line, the orientation of a plane, or the position of a point in space. In data acquisition, angles are used to measure the orientation of a device or object relative to a reference point, such as the direction of movement or the orientation of a sensor.
Answer Delay – If a connected e.bloxx/q.bloxx module or extension module does not communicate with the e.series/q.series controller, the e.bloxx/q.bloxx module will indicate an error in the measurement system. Here the answer delay of the modules can be defined before and error will be indicated.
Anti-Aliasing Filter – A type of filter that is used before a signal sampler that restricts the bandwidth of a signal to satisfy the sampling theorem. These are commonly used at the input of a digital signal processing system. A low pass filter that allows the desired low frequency component of the input waveform through, but stops the higher frequency components that can lead to aliasing errors (See Alias).
Argument – An Input parameter to a program.
ARINC 429 – An avionics interface protocol which is the standard communications link in virtually all modern commercial aircraft.
ASCII – The American Standard Code for Information Interchange is a character-encoding scheme that is originally based on the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text. ASCII includes definitions for 128 characters: 33 are non-printing that affect how text is spaced and processed, the other 95 are printable characters (including space).
Assembler – A program that translates assembly language instructions into machine language instructions.
Assembly Language – A machine oriented language in which mnemonics are used to represent each machine language instruction for a particular CPU.
ASTM – American Society for Testing and Materials.
Asynchronous – (1) Hardware – A property of an event that occurs at an arbitrary time, without synchronization to a reference clock. (2) Software – A property of a function that begins an operation and returns prior to the completion or termination of the operation.
Automotive – The process of collecting, storing, and analyzing data related to the performance of a vehicle. It involves the use of various sensors, such as accelerometers, gyroscopes, and pressure sensors, to record and measure various elements of a vehicle’s performance. Automotive data acquisition can be used to track a vehicle’s performance over time, diagnose problems, and develop vehicle-specific solutions to improve performance. It is also used to compare different vehicles and identify areas of improvement.
Average Filter – With this function an arithmetic averaging over several measured values is carried out. Thus the measurement rate is decreased, but the resolution is considerably increased. The number of averaging samples can be entered. This number determines how many measured values are used to calculate one averaged value.
B-Type Thermocouple – Platinum-rhodium thermocouple with a temperature range of 600 to >1700 °C.
Backbone – The primary-level of a hierarchical computer net-work connected to lower-level nodes in the hierarchy.
Background Acquisition – Background Data Acquisition refers to data that is acquired while another program or processing routine is running in the foreground without apparent interruption
Background Noise – Interfering signals that can cause disturbance affecting a signal that may distort the intended signal.
Backplane – A backplane is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbone to connect several printed circuit boards together to make up a complete computer system.
Band-Pass Filter – Is a device that passes frequencies with a certain range and rejects frequencies outside than range. AN RLC (resistor-inductor-capacitor) circuit is an example of electronic band-pass filter. The combination of a low-pass and high-pass filter can create a band-pass filter.
Band-Reject Filter – Also known as a notch filter, is a type of filter that allows most frequencies to pass through, except for a specific frequency band that is attenuated, or rejected. This type of filter is commonly used in data acquisition systems to reduce interference from unwanted signals that lie within the frequency range of interest. Band-reject filters can be used to reject wide or narrow frequency bands, depending on the application.
Base Address – A memory address that serves as the starting ad-dress for programmable registers. All other addresses are located by adding to the base address.
Batch process – Any process on which operations are carried out on a limited number of articles, as opposed to continuous process.
Baud – Is synonymous to symbols per second per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes. A baud rate, by definition, means the number of times a signal in a communications channel changes state or varies. A 2400 baud rate means that the channel can change states up to 2400 times per second.
Bessel – A filter commonly used in data acquisition systems to reduce signal ringing. They are a type of low-pass filter which allow low-frequency signals to pass through while blocking or attenuating high-frequency signals. Bessel filters have a sharper roll-off than other low-pass filters, such as Butterworth filters, which makes them well-suited for applications that require a steep roll-off band.
Bipolar – A signal range that includes both positive and negative values (for example, -5 V to +5 V).
Bit – The basic unit of information storage, a single binary digit that is either 0 or 1. Bit – One binary digit (either 0 or 1).
Block Mode – A high-speed data transfer in which the address of the data is sent followed by a specified number of back-to-back data words.
Bridge Factor – This indicates how many active strain gages are in the Wheatstone bridge. At quarter bridge applications, usually there is only one strain gage in the bridge, so the factor is 1. Therefore the factor is 2 when using 2 active gages.
Burst Mode – A high-speed data transfer in which the address of the data is sent followed by back-to-back data words while a physical signal is asserted.
Bus – The group of conductors that interconnect individual circuitry in a computer. Typically, a bus is the expansion vehicle to which I/O or other devices are connected. Examples of PC buses are the ISA and PCI buses.
Bus Master – A type of a plug-in board or controller with the ability to read and write devices on the computer bus, without using the host CPU.
Butterworth – a type of filter used in data acquisition systems to reduce aliasing error. It is a low-pass filter that has a maximally flat frequency response in the passband, meaning that it does not introduce any ripples or distortions in the signal. This makes it ideal for use in anti-aliasing filters, as it reduces the error caused by aliasing without introducing any additional distortion. Butterworth filters are classified by order, with higher order filters having a sharper roll-off and more attenuation in the stopband.
Byte – Eight related bits of data, an eight-bit binary number. Also used to denote the amount of memory required to store one byte of data. A byte may represent 256 unique numbers (typically from 0 to 255 in the decimal system)
Cache – High-speed processor memory that buffers commonly used instructions or data to increase processing throughput.
Calibration – The process of determining the relationship be-tween the output of a measurement device, and the input data, and comparing it against a measurement standard. In most cases, the term calibration also includes the process of adjusting the output of the measurement device to comply with the measurement standard.
CANopen – Is a communication protocol and device profile specification for embedded systems used in automation. CANopen implements the layers above and including the network layer. The standard consists of an addressing scheme, several small communication protocols, and an application layer defined by a device profile.
Capacitance – The amount of a stored (or separated) electrical charge for a given electrical potential, measured in farads (F).
Carrier Frequency – The transmission of a fixed frequency that has been changed or modified to carry data or information. The frequency is usually measured in Hertz (cycles per second).
CE – Conformite Europeene. A mark designating product’s compliance with all applicable European Union legal requirements.
Channel List – A variable length list of channels and their associated gains specifying which analog input channels to convert to digital values. In continuous A/D acquisition mode, the list wraps around to the first channel after it reaches the end. The channels need not be in any particular order.
Chebyshev – a filter used in data acquisition systems to help reduce noise in the signal being acquired. They are designed to have a steep roll-off in the passband, meaning that signals above the cut-off frequency are greatly attenuated. Chebyshev filters are designed to have a ripple in the passband, meaning that the gain of the filter in the passband is not constant over the entire range, but has some variation. This is in contrast to other types of filters such as Butterworth filters, which have a flat passband with no ripple. Chebyshev filters are designed to trade off a small amount of ripple in the passband for a steeper roll-off in the stopband.
Chromel – A 90% nickel alloy with about 10% chromium, used with Alumel in K-type thermocouples.
Circular Buffer – A circular buffer is available on a Gantner Instruments controller. When reading data from the buffer, always all data available in the buffer are fetched. With the maximum possible buffer size the transfer may take some time. Reduce the buffer size if only a few data shall be fetched.
CMRR – Common-Mode Rejection Ratio. A measure of an instrument’s ability to reject interference from a com-mon-mode signal, usually expressed in decibels (dB).
Code Generator – A software program, controlled from an intuitive user interface, that creates syntactically correct high-level source code in languages such as C or Basic.
Cold Junction Compensation (CJC) – Compensation for ambient temperature when a thermocouple is used in a data acquisition system; Thermocouples measure the temperature difference between two points, not absolute temperature. To measure a single temperature one of the junctions – normally the cold junction – is maintained at a known reference temperature and the other junction is at the temperature to be sensed.
Having a junction of known temperature, while useful for laboratory calibration, is not convenient for most measurement and control applications. Instead, they incorporate an artificial cold junction using a thermally sensitive device such as a thermistor or diode to measure the temperature of the input connections at the instrument, with special care being taken to minimize any temperature gradient between terminals. Hence, the voltage from a known cold junction can be simulated, and the appropriate correction applied. This is known as cold junction compensation.
Combustion Analysis – The process of collecting and analyzing data related to combustion processes, such as engine performance or fuel consumption. This data can be used to understand how engines are performing, diagnose problems, and improve engine efficiency. Data acquisition systems can be used to measure various physical and chemical properties of combustion processes, such as air-fuel ratios, exhaust gas temperatures, and emissions. The collected data can then be used to identify and quantify problems, compare performance of different engines, and optimize engine performance.
Common-Mode Range – The input range over which a circuit can handle a common-mode signal.
Common-Mode Signal – The mathematical average voltage, relative to the computer’s ground, of the signals from a differential input.
Common Mode Rejection Ratio – Abbreviated CMRR, is an important measure for strain gage amplifiers. A strain gage signal in a Wheatstone bridge is superimposed on a common mode voltage equal to half the excitation voltage. CMRR is a measure of how well the amplifier rejects common mode voltages.
Common Mode Signal/Voltage – A signal that appears equally, with respect to a local circuit common, on both lines of a 2-wire cable not connected to earth, sheild, or a local common. Typically, this is a an unwanted signal that needs to be rejected by the input signal. The common mode voltage is the average of the two signal voltages with respect to the local common.
Component Software – An application that contains one or more component objects that can freely interact with other component software. Examples include OLE enabled applications such as Microsoft Visual Basic and OLE Controls for virtual instrumentation in Component Works.
COM port – A serial device connectivity port on a PC, often RS-232.
Control – Control in data acquisition is the process of collecting data from various sources and using that data to make decisions or take actions. It involves both manual and automated processes to ensure that the data collected is accurate and up-to-date. Control in data acquisition is also used to monitor the performance of systems and equipment, and to identify any potential problems or issues. Control in data acquisition is important for a wide range of industries, from energy and manufacturing to healthcare and transportation.
Control Register(s) – Registers containing bits that initiate control signals for various onboard subsystems.
Conversion Time – The time elapsed, in an analog input or output system, from the moment a channel is interrogated (such as with a read instruction) to the moment that accurate data is available.
Counter/Timer – A circuit such as the Intel 8254 device that counts external pulses or clock pulses (timing).
Counters – In digital logic and computing, a counter is a device that stores and sometimes displays the number of times a particular event or process occurs, often in relationship to a clock signal. Counters can be implemented in various ways, useful for different applications. Counter circuits are digital in nature and count in natural binary.
Coupling – The manner in which a signal is connected from one location to another.
Crosstalk – An unwanted signal on one channel induced by signal activity on another nearby channel.
CSV – Stands for Comma Separated Values and is a type of data file format used to store tabular data. It is structured in a way that each line of the file represents a single record and each record consists of one or more fields, where the fields are separated by commas. This makes it a popular choice for data acquisition, as it is easy to read and store data in a CSV file.
Current – In data acquisition, current is a measure of an electrical current, usually in the form of volts, amperes, or milliamperes. Current is commonly used to measure the amount of electrical energy being transferred through a circuit or system. It is also used to measure the amount of current supplied to a device, such as a motor or other load. Current is measured in various ways, depending on the type of system and the type of device it is measuring.
Current Drive Capability – The amount of current a digital or analog output channel is capable of sourcing or sinking while still operating within voltage range specifications.
Current Sinking – The ability of a DAQ board to dissipate current for analog or digital output signals.
Current Sourcing – The ability of a DAQ board to supply current for analog or digital output signals.
Cutoff Frequency – Also known as corner frequency or break frequency, is a boundary in a system’s frequency response where energy flowing through a system begins to reduce rather than pass through.
D/A – Digital-to-analog
DAC – Digital-to-analog converter. An integrated circuit that converts a digital number into a corresponding analog voltage or current.
DAC Conversion Start – Signal used to start the conversion process of digital value to an analog output. The source of this signal can be either an internal DAC synchronous clock or an external asynchronous signal. This is a common signal fed to both DACs.
DAQ – An abbreviation for Data acquisition.
Dashboard – A dashboard in data acquisition is a tool that allows users to collect, store, and visualize data and analytics. It provides an overview of a system’s performance and provides real-time feedback and alerts. Dashboards are often used to monitor the health of a business, department, or process, and they enable users to spend less time gathering data and more time analyzing it. Dashboards usually contain graphical elements such as charts, graphs, and tables, and they can be customized to show specific key performance indicators (KPIs) that are relevant to the user.
Data Acquisition – (1) The process of automatically collecting and measuring electrical signals from sensors, transducers, and test probes or fixtures and inputting them to a computer for processing; (2) Collecting and measuring the same kinds of electrical signals with A/D and/or DIO boards plugged into a PC, and possibly generating control signals with D/A and/or DIO boards in the same PC.
Data Analysis – The process of analyzing the collected data to gain insights and draw conclusions. This can involve both quantitative and qualitative analysis, and often requires the use of statistical techniques to identify patterns and trends in the data. Data analysis can help to identify correlations between different variables, uncovering relationships that would otherwise be difficult to spot. It can also help to identify outliers, or values that are significantly different from the rest of the data. In addition to helping with decision-making, data analysis can also be used to develop predictive models, which can be used to forecast future trends.
Data Length – Indicates the set data format. 1 Byte = Boolean or 2 Bytes = Integer.
Data Logger – A stand alone data acquisition device that acquires data and stores it in local memory from which it may then be downloaded to a computer for subsequent analysis and display.
Data Recorder – Another name for a data logger, though data recorders are typically higher performance and offer higher sample rates than a typical data logger.
Data Recording – The process of capturing and storing data in an organized manner for later retrieval and analysis. Data recording may involve capturing information from various sources such as sensors, cameras, audio and video recordings, and manual input from users. The data can then be stored in a database, file system, or other data storage system for later retrieval and analysis. Data recording is an essential part of data acquisition and is used in applications such as monitoring environmental conditions, tracking inventory, and analyzing customer behavior.
Data Storing – The process of collecting and storing data over a period of time in order to analyze specific trends or record the state of a system at different points in time. Data is typically collected from sensors, instruments, or other sources and can be stored in a variety of formats, such as text files, databases, or cloud data storage services. Data stored in this way can then be used to analyze trends, make predictions, or develop models and simulations.
Data Visualization – The practice of representing data in a visual format, such as charts, graphs, maps, and infographics. It helps to make data easier for the human brain to process and understand, allowing for quick decisions and insights to be made based on the data. Data visualization can be used for exploratory data analysis, to identify patterns and trends in data, to monitor the progress of a project or process, or to present the results of data analysis.
dB – Decibel. The unit for expressing a logarithmic measure of the ratio of two signal levels: dB=20log10 V1/V2, for signals in volts.
Digital Domain – The process of sampling signals that measure real-world physical conditions, such as temperature, pressure, sound, or light, and converting the resulting samples into digital numeric values that can be stored, analyzed, and manipulated. This process typically involves the use of an analog-to-digital converter (ADC) to convert the analog signal into a digital signal, which can then be further processed and analyzed.
Discrete events – Discrete events in data acquisition refer to a sensor output or measurement that can only take on a finite set of values, such as on/off, true/false, or 0/1. These types of measurements are often used to measure the state of a system, such as the position of a switch or the speed of an engine. Discrete events are typically measured with a counter input on a data acquisition system, and can be used to measure the frequency of an event or the total number of events that have occurred.
Displacement – Displacement in data acquisition refers to the process of measuring changes in a physical parameter, such as the displacement of a structure or the velocity of a fluid. Data acquisition systems are used to measure the displacement of a structure, object, or fluid, by sampling signals that measure the physical parameters of interest. This data can then be analyzed to track changes in the measured parameter over time, and can be used to detect any anomalies or abnormalities in the measured parameter.
Distance – Distance measurement in data acquisition is the process of measuring the distance between two points or from a point to an object. This is often done using optical sensors, laser rangefinders, or other devices. Distance measurement is used in data acquisition for a variety of applications, such as mapping, surveying, navigation, and robotics. It can also be used to measure the distance between two objects in 3D space, or to measure the distance between a point and an object.
DHCP – The Dynamic Host Configuration Protocol (DHCP) is an auto configuration protocol used on IP networks. Computers that are connected to IP networks must be configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a network administrator.
Differential Input – An analog input consisting of two terminals, both of which are isolated from computer ground, whose difference is measured.
DIO – Digital input/output.
DLL – Dynamic Link Library. A software module in Micro-soft Windows containing executable code and data that can be called or used by Windows applications or other DLLs. Functions and data in a DLL are loaded and linked at run time when they are referenced by a Windows application or other DLLs.
DMA – Direct memory access. A method by which data can be transferred to/from computer memory from/to a device or memory on the bus while the processor does something else. DMA is the fastest method of transferring data to/from computer memory.
DNL – Differential Non-linearity. A measure in LSB of the worst-case deviation of code widths from their ideal value of 1 LSB.
Drivers – Software that controls a specific hardware device, such as DAQ boards.
DSA – Dynamic Signal Acquisition. It is a type of data acquisition system that is designed to measure and acquire signals with varying levels of amplitude and frequency, such as those found in audio, vibration, and radar applications. DSA systems typically employ multiple signal-conditioning techniques, such as oversampling, noise-shaping, and signal-averaging, to ensure accurate and reliable measurements. They also employ proprietary algorithms and signal processing techniques to provide enhanced features, such as dynamic range and signal-to-noise ratio, which allow for higher precision and greater accuracy in signal acquisition and measurement.
DSP – Digital Signal Processor, is a specialized microprocessor with an optimized architecture for the fast operational needs of digital signal processing. The Gantner Instruments measurement modules use DSPs to process the measured data.
Dual-Ported Memory – Memory that can be simultaneously accessed by more than one controller or processor.
Dynamic Range – The ratio of the largest signal level a circuit can handle to the smallest signal level it can handle (usually taken to be the noise level), normally expressed in dB.
EEPROM – Electrically erasable programmable read-only memory. ROM that can be erased with an electrical signal and reprogrammed.
Electromagnetic Compatibility – Abbreviated EMC, refers to the ability of a piece of equipment to perform as intended while being installed in a electromagnetic environment. The equipment should be intolerable to interference within the environment and at the same time without introducing intolerable interference into the environment. Therefore, equipment that has both high immunity and low emissions is considered compatibile to other equipment in the local environment.
Electrostatic Induction – Electrostatic induction is a method to create or generate static electricity in a material by bringing an electrically charged object near it. This causes the electrical charges to be redistributed in the material, resulting in one side having an excess of either positive (+) or negative (−) charges.
Elliptic Filter – A type of filter used in data acquisition and other signal processing systems. It is a type of filter that has a maximally flat magnitude response in the passband and monotonically decreasing frequency response in the stopband. It offers high selectivity with moderate roll-off slopes, and is usually used in applications that require a high degree of rejection of unwanted frequencies. Elliptic filters also provide stopband ripple control and fast transition from passband to stopband, making them ideal for use in data acquisition systems.
Embedded Controller – A control device built into (embedded in) a host de-vice. Monitoring and control are handled by the same CPU as general system operation.
Encoder – A device that converts linear or rotary displacement into digital or pulse signals. The most popular type of encoder is the optical quadrature encoder, which uses a rotating disk with alternating opaque areas, a light source, and a photo detector to indicate a rotary position.
EPROM – Erasable programmable read-only memory. ROM that can be erased (usually by ultraviolet light exposure) and reprogrammed; is a type of memory chip that retains its data when its power supply is switched off (non-volatile).
ESD – Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. A buildup of static electricity can be caused by tribocharging or by electrostatic induction.
ESD Equipment – ESD-safe packaging protects products and equipment from electrostatic discharge (ESD), which can result in product damage or failure. Products like anti-static bubble wrap, conductive boxes, and ESD-safe tape ensure products are free of static electricity during shipping operations.
EtherCAT – Ethernet for Control Automation Technology, is an open high performance Ethernet-based fieldbus system. The goal was to apply Ethernet to automation applications that require short data update times with low communication jitter, all with low hardware costs.
Ethernet – Is a family of computer networking technologies for local area networks (LANs) first introduced in 1980. Systems that use Ethernet for communications divide a stream of data into individual packets called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted.
Events – Signals or interrupts generated by a device to notify another device of an asynchronous event. The contents of events are device-dependent.
Excitation Voltage – The nominal voltage required for excitation of a circuit. Excitation is the process of generating a magnetic field by means of an electric current.
External Trigger – A voltage pulse from an external source that triggers an event such as A/D conversion.
Field Length – The field length determines, with how many positions a value will be output or displayed when measuring (1 to 8). For a precision > 0 the field length is the number of characters before plus after the decimal point plus one (for the decimal point).
FIFO – First-In First-Out Memory Buffer. The first data stored is the first data sent to the acceptor.
Filter – A device that allows certain parts of a signal to pass through while blocking others. In data acquisition systems, the most common type of filter used is a low pass, anti-aliasing filter.
Firewall – A device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. A firewall installed on the PC running Gantner software must allow access to Q.gate, Q.pac, and other controllers.
Fixed-Point – A format for processing or storing numbers as digital integers.
Floating point – In computing, this describes a method of representing real numbers in a way that can support a wide range of values. The term floating point refers to the fact that the radix point (decimal point or binary point) can float, that it can be placed anywhere relative to the significant digits of the number; A format for processing or storing numbers in scientific notation (digits multiplied by a power of 10).
FFT – Fast Fourier Transform (FFT) is an algorithm used for data acquisition (DAQ) in order to analyze and measure signals from plug-in devices. It is a way of breaking down a signal into its individual frequencies and amplitudes, allowing for more accurate analysis and understanding of the signal. FFT is often used in fields such as engineering, medicine, finance and physics, and is a very powerful tool for analyzing and understanding complex signals.
FPGA – Is a field-programmable gate array, an integrated circuit designed to be configured by the customer or designer after manufacturing. They contain programmable logic components called logic blocks and a hierarchy of reconfigurable interconnects that allow the blocks to be wired together.
FTP – File Transfer Protocol, is a standard network protocol used to transfer files from one host to another over a TCP based network such as the internet. Use this method to upload web pages and other documents from a personal machine to a public web hosting server.
Full Bridge Circuits – Not often used compared to a half bridge or quarter bridge circuit, but is the optimal configuration for strain gages. It provides the highest sensitivity, fewest error, produces highest output, and noise being a non-factor. A full bridge contains four strain gages, all mounted on the test member (two on top to measure tension and two on the bottom to measure compression). As the test member deflects, two gages in tension and two gages in compression have a change of resistance, causing the bridge to unbalance and produces a output proportional to the displacement.
Full Duplex – FDX, sometimes called a double-duplex system, allows communication in both directions, unlike half duplex, allows this to happen simultaneously. Land line telephone networks is an example of a full duplex since they allow both callers to speak and listen at the same time.
Function – A set of software instructions executed by a single line of code that may have input and/or output parameters, that returns a value when executed.
Gain – The factor by which a signal is amplified, sometimes expressed in dB.
Gain Accuracy – A measure of deviation of the gain of an amplifier from the ideal gain.
Galvanic Isolation – Is the principle that all functional sections of an electrical system are isolated from each other. This is done to prevent the movement of charge carrying particles from one section to another. This design aspect is ideal when two or more electric circuits must communicate but have their grounds have different potentials. An increase in safety is also achieved because accidental current that could pass through a person’s body to the ground is prevented. Information between sections can still be transferred in other ways such as capacitance, induction, electromagnetic waves, and other mechanical ways.
Gage Factor – GF or strain factor of a strain gage is the ratio of relative change in electrical resistance to the mechanical strain, which is the relative change in length.
GND (Ground) – The electrical ground (aka earth). Is the reference point in an electrical circuit from which other voltages are measured or is a common return path for electric current, a direct physical connection to the Earth. In powered equipment, exposed metal parts are connected to ground to prevent contact with dangerous voltage if electrical insulation fails.
GPIB – General Purpose Interface Bus. Also known as IEEE-488, the GPIB was originally developed by Hewlett Packard and called the HPIB.
GPS – Global Positioning System. A series of satellites is used to provide accurate location and velocity information to both ground based and land based devices. A powerful and often ignored benefit in data acquisition applications is the ability of a GPS system to generate extremely accurate timing information. One microsecond accuracy is available with inexpensive units and much tighter specifications are available from some vendors.
Ground – In terms of data acquisition systems, a ground is typically where system current is returned. In single ended systems the negative terminal of the sensor is typically connected to ground.
Ground Loop – Many measurements are made between an input signal and ground. However, ground is not an absolute reference point and current flowing in wires between various ground connections can cause the potential at different “ground” points in the system to be at different potentials. These differences then manifest themselves as errors in the measurement.
GUI – Graphical User Interface. An intuitive, easy-to-use means of communicating information to and from a computer program by means of graphical screen displays. GUIs can resemble the front panels of instruments or other objects associated with a computer program.
Half Bridge Circuit – A bridge circuit where only two strain gages are used on a test member compared to the four used in a full bridge. Two discrete resistor create the bridge. This configuration is typically used due to physical constraints and obstacles not allowing the use of four strain gages.
Half Duplex – HDX, is a system that provides communication in both directions, but only one direction at a time (not simultaneously). Once a party begins receiving a signal, it must wait for the transmitter to stop transmitting, before replying.
Hall Effect Sensor – Is a transducer that varies its output voltage in response to a magnetic field. They are used for proximity switching, positioning, speed detection, and current sensing applications. Hall sensors are normally used to time the speed of wheels and shafts.
Handler – A device driver that is installed as part of the operating system of the computer.
Hardware – The physical components of a computer system, such as the circuit boards, plug-in boards, chassis, enclosures, peripherals, cables, and so on.
High-Pass Filter – Is an electronic filter that passes high frequency signals but attenuates signals with frequencies lower than the cutoff frequency. They are used to block DC from circuitry sensitive to non-zero average voltages or RF devices.
Hz – The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic signal.
I/O – Input/Output. The transfer of data to/from a computer system involving communications channels, operator interface devices, and/or data acquisition and control interfaces.
ICP® (piezoelectric vibration sensor) – A simple yet powerful 2-wire interface developed by PCB Piezo Electronics® to facilitate connection of Piezo Crystal based vibration sensors to data acquisition systems. Also referred to as IEPE.
IEPE/ICP Sensor – An Integrated electronic piezoelectric sensor/accelerometer is a class of accelerometer that incorporates an electronic amplifier that uses a single two-pole coaxial connector for both power input and signal output. This device is also known as an Integrated Circuit Piezoelectric. The main advantages of an IEPE are small size, light weight, robustness, and low cabling cost.
IIR – Infinite Impulse Response, is a property of signal processing systems. Digital IIR filters, the output feedback is immediately apparent in the equations defining the output. Unlike a FIR filter, they have the feedback and are known as recursive digital filters and have a better frequency reponse at the same order.
IMD – Intermodulation Distortion. The ratio, in dB, of the total rms signal level of harmonic sum and difference distortion products, to the overall rms signal level. The test signal is two sine waves added together.
INL – Integral Non-linearity. A measure in LSB of the worst-case deviation from the ideal A/D or D/A transfer characteristic of the analog I/O circuitry.
Input Bias Current – The current that flows into the inputs of a circuit.
Input Impedance – The measured resistance and capacitance between the input terminals of a circuit.
Input Offset Current – The difference in the input bias currents of the two inputs of an instrumentation amplifier.
Instrumentation Amplifier – A circuit whose output voltage with respect to ground is proportional to the difference between the voltages at its two inputs.
Integral Control – A control action that eliminates the steady-state offset inherent in proportional control.
Integrating ADC – An ADC whose output code represents the average value of the input voltage over a given time interval.
Interpreter – A software utility that executes source code from a high-level language such as Basic, C, or Pascal, by reading one line at a time and executing the specified operation.
Interrupt – A computer signal indicating that the CPU should suspend its current task to service a designated activity.
IOT – The internet of things, or IoT, is a system of interrelated computing devices, mechanical and digital machines, objects, animals or people that are provided with unique identifiers (UIDs) and the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction.
IPC – Inter-process Communication. Protocol by which processes can pass messages. Messages can be either blocks of data and information packets, or instructions and requests for process to perform actions. A process can send messages to itself, other processes on the same machine, or processes located anywhere on the network.
Isolation – Isolation in data acquisition is the separation of one signal from another to prevent unintentional interaction between them. This is typically done by using an isolation amplifier which amplifies the signal without introducing ground loops or other errors. Isolation amplifiers can also be used to reduce the effects of common mode voltages, which can interfere with or even damage data acquisition equipment.
Isolation Voltage – The voltage that an isolated circuit can normally withstand, usually specified from input to input and/ or from any input to the amplifier output, or to the computer bus.
k – Kilo, the standard metric prefix for 1,000, or 103, used with units of measure such as volts, Hertz and meters.
K (computer) – Kilo, the prefix for 1,024, or 210, used with byte in quantifying data or computer memory.
kbytes/s – A unit for data transfer that means 1,000 or 103 bytes/s.
LabVIEW™ – A popular data acquisition programming language developed by National Instruments®
LAN – Local Area Network, is a computer network that interconnects computers in a limited area such as a home, school, laboratory, or office. Compared to WANs (wide area networks), LANs usually have higher data-transfer rates, smaller geographic areas, and don’t require leased commuication lines.
LIN – LIN (Local Interconnect Network) The need for a cheap serial network arose as the technologies and the facilities implemented in the car grew, while the CAN bus was too expensive to implement for every component in the car. European car manufacturers started using different serial communication technologies, which led to compatibility problems.
In the late 1990s, the LIN Consortium was founded by five automakers (BMW, Volkswagen Group, Audi Group, Volvo Cars, Mercedes-Benz), with the technologies supplied (networking and hardware expertise) from Volcano Automotive Group and Motorola. The first fully implemented version of the new LIN specification (LIN version 1.3) was published in November 2002. In September 2003, version 2.0 was introduced to expand capabilities and make provisions for additional diagnostics features. LIN may be used also over the vehicle’s battery power-line with a special LIN over DC powerline (DC-LIN) transceiver.
LIN over DC powerline (DC-LIN) is being standardized as ISO/AWI 17987-8.
CAN in Automation has been appointed by the ISO Technical Management Board (MTB) as the Registration Authority for the LIN Supplier ID standardized in the ISO 17987 series.
Linearity – The adherence of device response to the equation R = KS, where R =response, S = stimulus, and K = a constant.
Load Cell – A transducer which converts force into a measurable electrical output. It is commonly used in data acquisition systems to measure weight, force, or pressure. Load cells are typically constructed with strain gauges, which are bonded to a surface and measure the strain caused by a force. The strain gauges generate an electrical signal which can then be interpreted by a data acquisition system to determine the magnitude of the force being applied.
LocalBus – Is a computer bus that connects directly, the CPU to one or more slots of the expansion bus. This method avoids bottlenecking created by the expansion bus, creating a much faster throughput. The LocalBus (RS485) between a Gantner Instruments controller (i.e. Q.gate or Q.pac) and I/O modules can achieve speeds up to 48 Mbps.
Logger – See Data Logger.
Low-Pass Filter – Is an electronic filter that passes low frequency signals but attenuates signals with frequencies higher than the cutoff frequency. Low-pass filters provide a smoother form of a signal, removing the short-term fluctuations and leaving the longer-term trend.
LSB – Least significant bit. In terms of data acquisition and measurement systems, the LSB is the smallest change in input that can be detected by the system’s A/D converter.
LVDT – Linear Variable Differential Transformer, is a type of electrical transformer that is used for measuring linear/transitional displacement. The LVDT has three solenoidal coils placed end-to-end around a tube. The center coil is the primary, and the two outer coils are the secondaries. A cylindrical ferromagnetic core, attached to the object whose position is to be measured, slides along the axis of the tube.
LXI – Designed as the Successor to GPIB, LXI is a standard developed by the LXI Consortium, and is an abbreviation for LAN extensions for Instrumentation. More information can be found at the LXI Standard Website.
M – (1) mega, the standard metric prefix for 1 million or 106, when used with units of measure such as volts and Hertz; (2) mega, the prefix for 1,048,576, or 220, when used with byte to quantify data or computer memory.
Macro – Is a set of rules that specifies how input sequences should be mapped to output sequences.
Mbytes/s – A unit for data transfer that means 1 million or 106 bytes/s.
Microphone – A device used to acquire sound data. It works by converting sound waves into electrical signals, which can then be processed, analyzed, and stored for further use. The microphone itself can vary in size and type, depending on the application and the amount of sound being recorded. Microphones are commonly used in recording studios, sound systems, and for scientific data acquisition.
MMI – Man-Machine Interface, also Human-Machine Interface(HMI): The means by which an operator interacts with an industrial automation system; often a GUI.
Modbus – A defacto standard communications protocol used in a wide variety of Industrial Control and DAQ (data acquisition) systems industrial control and monitoring equipment. Modbus was developed by Modicon in 1979 as a means to facilitate communication in their programmable controller products.
Modular DAQ – Modular data acquisition is a type of data acquisition system that uses modular components, such as modules and controllers, to measure and collect data. The modular components are usually connected to a computer or a central processing unit, which can be used to process the data and present it in a useful format. Modular data acquisition systems offer flexibility, as they can be customized to meet the specific needs of an application. Modular data acquisition systems are often used in industrial processes, research projects, and other applications where high accuracy and large amounts of data need to be collected and analyzed.
Monitoring – The process of collecting and analyzing data from various sources in order to assess the performance and health of a system or process. This process includes monitoring the current status of systems or processes and collecting data on any changes or anomalies in order to identify potential problems or opportunities. Data acquisition monitoring can be used to improve efficiency and accuracy, identify system weaknesses, and monitor the performance of a system over time.
MOSFET – The Metal-Oxide-Semiconductor Field-Effect Transistor is a transistor used for amplifying or switching electronic signals. The MOSFET is the most common transistor in both digital and analog circuits.
MTBF – Is an abberviation for a measure known as Mean Time Between Failures is the average duration between two failures. It serves as measure for the reliability of devices and systems. MTBF is the time, measured in hours, which one the producer declares as an average time, before a failure first time will appear at a product. At a MTBF-declaration of 100,000 hours, on average a
failure will appear after 11.4 years.
Multiplexer – Also known as a MUX, is a device that selects one of several analog or digital input signals and forwards the selected input in a single line. Multiplexers are mainly used to increase the amount of data that can be sent over the network within a certain amount of time and bandwidth. A multiplexer is also known as a data selector.
For long term monitoring that involves many channels (100+) at a slow rate, the Q.bloxx M108 multiplexer can be used with an A102 to support the connection of 8 channels. Up to 3 x M108’s can operate with 1 x A102.
Multitasking – A property of an operating system in which several processes can be run simultaneously.
Mux – Multiplexer. A switching device with multiple inputs that sequentially connects each of its inputs to its output, typically at high speeds, in order to measure several signals with a single analog input channel. Most data acquisition systems utilize multplexers to allow a single A/D converter to measure or monitor multiple inputs.
Noise – An undesirable electrical signal. Noise comes from external sources such as the AC power line, motors, generators, transformers, fluorescent lights, soldering irons, CRT displays, computers, electrical storms, welders, radio transmitters, and internal sources such as semiconductors, resistors, and capacitors.
Nonvolatile Memory – Computer memory that can retain the stored information even when the module is not powered. Examples are read only memory and flash memory. These forms are typically used as secondary storage or long term storage.
Number of Measurements for Block Transfer – Is the size of the data blocks, transmitted from FPGA to CPU. The internal cycle is lower or equal to 1 kHz. Therefore the block size has to be chosen properly, so that this rate is not exceeded.
NVH – Noise, Vibration, and Harshness (NVH) testing is a data acquisition technique used to measure and analyze the noise, vibration, and harshness characteristics of a product or system. It involves the use of specialized equipment, such as force transducers and accelerometers, to measure the input and output signals from a system, as well as a data acquisition system to collect and analyze the data. The resulting data can be used to identify and address any issues with the system’s performance, such as excessive vibration or noise levels.
PAC – See Programmable Automation Controller.
Paging – A technique used for extending the address range of a device to point into a larger address space.
PCI – Peripheral Component Interconnect. A high-performance expansion bus architecture originally developed by Intel to replace ISA and EISA. It offers a theoretical maximum transfer rate of 132 Mbytes/s. More information can be found at the PCI-SIG Website
PID Control – A three-term control mechanism combining proportional, integral, and derivative control actions. Also see proportional control and integral control.
PID Controller – A Proportional – Integral – Derivative Controller is a generic control loop feedback used in industrial control systems. A PID is the most common feedback controller. A PID controller calculates and error value as the difference between the measured process variable and a desired setpoint. The controller tries to minimize the error by adjusting the process control inputs. The controller calculates the proportional, the integral, and derivative values. The weighted sum of these three is used to adjust the process to eliminate the error between the process variable and desired setpoint.
Piezoelectric Sensor – A device that uses the piezoelectric effect to measure pressure, acceleration, strain, or force by converting it to an electrical charge. These sensors are used to ensure quality in a process control. These electromechanical systems react to compression but have zero deflection, a very rugged sensor that is also insensitive to electromagnetic fields and raditaion. The downside is that piezoelectric sensor can not be used for static measurements.
Pipeline – A high-performance processor structure in which the completion of an instruction is broken into its elements so that several elements can be processed simultaneously from different instructions.
PLC – See Programmable Logic Controller.
Plug and Play ISA – A specification prepared by Microsoft, Intel, and other PC-related companies intended to create PCs with plug-in boards that can be fully configured in software, without jumpers or switches on the boards.
Port – A communications connection on a computer or a remote controller.
Post-triggering – The technique used on a DAQ board to acquire a programmed number of samples after trigger conditions are met.
Potentiometer – Also known as a pot, in electronics is a three-terminal resistor with a sliding contact that forms an adjustable voltage dividier. If only two of the terminals are used, one end and the wiper it acts as a variable resistor. It is used for measuring electric potential (voltage). They are also commonly used to control electrical devices (i.e. volume control on a radio). They can also be used as a position transducer (i.e. joystick). Most importantly, we can use a potentiometer as an instrument for measuring potential (voltage) in a circuit; An electrical device of which the resistance can be manually adjusted; used for adjustment of electrical circuits and as a transducer for linear or rotary position.
Pre-triggering – The technique used on a DAQ board to keep a continuous buffer filled with data, so that when the trigger conditions are met, the sample includes the data leading up to the trigger condition.
Precision – In channel configuration, determines the number of characters after the decimal point. The precision can amount from 0 to (field length – 2).
Pressure – In data acquisition, pressure is the measure of the force applied to a surface per unit area. It is often measured in units of pounds per square inch (psi) or kilopascals (kPa). Pressure can be a useful parameter to measure in many applications, such as measuring the pressure of an object in a liquid or measuring the pressure of a gas or liquid flowing through a pipe. Pressure readings can be used to determine the flow rate of a gas or liquid, or to measure the amount of force generated by a motor or other device. Pressure readings can also be used to determine the temperature of a gas or liquid.
Pressure Transducers – Millivolt Output: This is the most economical version. The output is directly proportional to the pressure transducer input power (voltage excitation). The output will change if the excitation changes, therefore it is important to use regulated power supplies. Since the mV signal is very low, the transducer itself should not be placed physically in a noisy environment. Voltage Output: These type of sensors use an integrated signal conditioning, providing the increased output level, typically 0-5 VDC or 0-10 VDC. Therefore unregulated power supplies are sufficient and these sensors are much less susceptible to electrical noise. A better alternative for industrial and harsh environments. 4-20 mA Output: These transmitters take advantage of the 4-20 mA signal, which is least susceptible to electrical noise that comes from electrical wire. This alternative is best used when the signals needs to be transmitted long distances (i.e. 1000 ft or more).
Profibus – Process Field Bus, is a standard for field bus communication in automation technology. It is not an openly published and royalty-free protocol. Specifically, Profibus DP (Decentralized Peripherals) is used to operate sensors and actuators via a centralized controller in production automation applications.
Programmable Automation Controller – Also commonly referred to as a PAC, these are stand-alone controllers that perform a function similar to a Programmable Logic Controller, but are programmed in standard programming languages (e.g. C or Visual Basic) rather that the Ladder Logic programming language used by most PLCs.
Programmable Logic Controller – Also commonly referred to as a PLC, these are highly reliable special-purpose computer used in industrial monitoring and control applications. PLCs typically have proprietary programming and net-working protocols, and special-purpose digital and analog I/O ports.
Programmed I/O – The standard method a CPU uses to access an I/O device– each byte of data is read or written by the CPU.
Propagation Delay – The amount of time required for a signal to pass through a circuit.
Proportional Control – A control action with an output that is to be proportional to the deviation of the controlled variable from a desired set point.
Protocol – The exact sequence of bits, characters and control codes used to transfer data between computers and peripherals through a communications channel, such as the GPIB.
PWM – Pulse-Width Modulation, is a commonly used technique for controlling power to inertial electrical devices, made by modern electronic power switches. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast pace. The longer the switch is on compared to the off periods, the higher the power supplied to the load is. PWM can be used to control the amount of power delivered to a load without incurring the losses that would result from linear power delivery by resistive means.
PXI – A modular instrumentation platform used for building test equipment and automation systems promoted by the PXI Systems Alliance (PXISA) and is an a abbreviation that stands for PCI extensions for Instrumentation.
OLE – Object Linking and Embedding. A set of system services, developed by Microsoft, that provides a means for applications to interact by linking and embedding document objects. Based on the underlying Component Object Model, OLE is object-enabling system software. Through OLE Automation, an application can dynamically identify and use the services of other applications, to build powerful solutions using packaged software. OLE also makes it possible to create compound documents consisting of multiple sources of information from different applications.
Operating System – Base-level software that controls a computer, runs programs, interacts with users, and communicates with installed hardware or peripheral devices.
Optical Isolation – The technique of using an optoelectrical transmitter and receiver to transfer data without electrical continuity to eliminate high-potential differences and transients.
Oscilloscope – An electronic instrument used for measuring and displaying signals in the form of a waveform. In data acquisition, oscilloscopes are used to measure and display physical signals such as voltage, current, and temperature. Oscilloscopes are used to analyze electrical signals, identify signal distortion and noise, and study the behavior of circuits. They are also used to measure frequency, phase, and other parameters of a signal. Oscilloscopes are a useful tool for debugging circuits, testing components, and measuring electrical signals.
Output Settling Time – The amount of time required for the analog output voltage to reach its final value within specified limits.
Output Slew Rate – The maximum rate of change of analog output voltage from one level to another.
Overhead – The amount of computer processing resources, such as time and/or memory, required to accomplish a task.
Overload – An overload occurs when the voltage of an incoming signal is higher than the voltage range the sensor or data acquisition device is designed to handle. This can damage the device, or cause inaccurate readings. To reduce the risk of overload, many data acquisition systems include protection circuits which will disconnect the sensor or device from the signal if it becomes overloaded.
Quadrature Encoder – A device used to measure rotation. The most popular type of encoder is the optical quadrature encoder, which uses a rotating disk with alternating opaque areas, a light source, and a photo detector. Each time the photo detector crosses the light (or dark) a signal is generated. These signals are then turned into rotational information by a quadrature encoder input devices.
Quantization Error – The inherent uncertainty in digitizing an analog value due to the finite resolution of the conversion process.
Quarter Bridge Circuit – This version of a bridge circuit only uses one strain gage and three bridge completion resistors. This configuration has the smallest output with alot of noise potential.
Real Time – A property of an event or system in which data is processed as it is acquired instead of being accumulated and processed at a later time.
Relative Accuracy – A measure in LSB of the accuracy of an ADC. It includes all non-linearity and quantization errors. It does not include offset and gain errors of the circuitry feeding the ADC.
Repeatability – Also known as test-retest reliability is the variation in measurements taken by a single person or instrument on the same item and under the same conditions. A measurement may be said to be repeatable when this variation is smaller than some agreed limit.
Resolution – The smallest signal increment that can be detected by a measurement system. Resolution can be ex-pressed in bits, in proportions, or in percent of full scale. For example, a system has 12-bit resolution, one part in 4,096 resolution, and 0.0244 percent of full scale.
Resource Locking – A technique whereby a device is signaled not to use its local memory while the memory is in use from the bus.
Ribbon Cable – A flat cable in which the conductors are side by side.
RJ45 – RJ45 is a type of connector commonly used for Ethernet networking. It looks similar to a telephone jack, but is slightly wider. Since Ethernet cables have an RJ45 connector on each end, Ethernet cables are sometimes also called RJ45 cables.
Rotor Balancer – A tool used in data acquisition to measure the unbalance of a rotating object, such as a rotor. It uses sensors to measure the vibration caused by the unbalance and then uses software to calculate the amount of unbalance and its location. The data is then used to adjust the rotor so that it is balanced, thus reducing the vibration and improving the performance of the system.
RPM – Revolutions per minute, is a measure of the rotational speed of an object. In data acquisition, RPM is often used to measure the speed of a motor or other rotating object. RPM is typically measured using a tachometer or a rotary encoder, which measure the number of rotations per minute of the object in question. RPM can also be measured using a combination of other sensors such as a speed sensor or a proximity sensor, which measure the speed of the object in relation to a reference point. RPM is an important parameter to measure when collecting data from rotating machinery, as it can provide insight into the performance of the machinery and help diagnose any potential issues.
RMS – The Root Mean Square also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is useful when variates are positive and negative. The RMS can be calculated for a series of values or a varying function. The value is a square root of the mean of the squares.
RS-232 – Recommended Standard 232 is a standard for serial communication. It is commonly used in computer serial ports. It is used to connect a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment). The standard defines the electrical characteristics and timing of signals, the meaning of signals, and the physical size and pin out of the connectors; in most AV devices, you’ll find it is connected via a standard 9-pin Dsub connector. Though a common data connectivity in the AV world, RS-232 does not transfer audio or visual signals, but is used to transmit control data between devices.
RS-485 – RS-485, also known as TIA-485(-A), EIA-485, is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems. Electrical signaling is balanced, and multipoint systems are supported; Digital communications networks implementing the RS-485 standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multi-drop configuration. These characteristics make such networks useful in industrial environments and similar applications.
RTD – Resistance thermometers, also called resistance temperature detectors or resistive thermal devices (RTDs), are temperature sensors that exploit the predictable change in electrical resistance of some materials with changing temperature, i.e. Pt100 and Pt1000; A metallic probe that measures temperature based upon its coefficient of resistivity.
RVDT – Rotary Variable Differential Transformer, is a type of electrical transformer used for measuring angular displacement. It is an electromechanical transducer that provides a variable alternating current (AC) output voltage that is linearly proportional to the angular displacement of its input shaft.
S/H – Sample-and-Hold. A circuit that acquires and stores an analog voltage on a capacitor for a short period of time.
S/s – Samples per second. Used to express the rate at which a data acquisition system samples an analog signal.
Sample Rate – Also referred to as the synchronization rate, defines how many data points the Q.brixx system will transfer to the host system. A higher sample rate means more data needs to be transferred via Ethernet.
SE – Single-Ended. A term used to describe an analog input that is measured with respect to a common ground.
Self-Calibrating – DAQ board that calibrates its own A/D and D/A circuits without external reference source.
Sensor – A device that responds to a physical stimulus (heat, light, sound, pressure, motion, flow, and so on), and produces a corresponding electrical signal.
Shock – In data acquisition, shock refers to an abrupt, sudden change in the value of a measured physical phenomenon, such as voltage, current, temperature, or pressure. It is typically caused by an external mechanical force, such as vibration or impact, and is often used to measure the severity of an event for analysis or testing purposes.
Shunt Resistor – A low resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current. Shunts allow meters to produce accurate readings in a much wider range. A shunt resistor is used to measure AC or DC electrical currents by the voltage drop the currents create across the resistance. By inserting a current shunt into a circuit whose current you want to measure, you can find the current by measuring the voltage drop across the shunt. Then knowing the resistance of the current shunt you can calculate the current using Ohm’s Law (I = V / R).
Signal Conditioner – A device used in data acquisition systems to interface with sensors. It modifies the output signal from the sensor to make it suitable for processing by a data acquisition system. Typical signal conditioning operations include amplification, filtering, linearization, isolation, and conversion from analog to digital. Signal conditioners are essential for ensuring accuracy and reliability in data acquisition systems.
Signal Conditioning – In electronics, signal conditioning is the manipulation of an analog signal in such a way that it meets the requirements of the next stage for further processing. In an analog-to-digital converter application, signal conditioning includes voltage or current limiting and anti-aliasing filtering.
Signal Source – Any device that produces a signal that can be used to measure a physical quantity. Common signal sources in data acquisition include sensors, signal generators, and transducers. The signal produced by the source is then converted into a digital signal and used as input for a data acquisition system.
Signal to Noise Ratio – Abbreviated as SNR or S/N, is a measure that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to signal noise. A ratio higher than 1:1 indicates more signal than noise.
Sinking Output (NPN) – Outputs that sink or pull current through the load. The typicaly load is the 24 VDC source. The modules with a sinking output require the load to be energized by a current. The current flows from the 24 VDC source to the load, through the NPN switch, to the 0 VDC line.
Sliding Filter – The Intelligent Sensor Modules: ISM 101, ISM 103, and ISM 108 also have the possibility of a sliding average filter. This filter calculates the average value between 2 following measured values. For an ISM 111 and ISM 112, a low pass and sliding filter can be used together. A measured value will first be processed by the low pass filter and then an average filter will be used.
SNR – Signal-to-Noise Ratio. The ratio of the overall rms signal level to the rms noise level, expressed in dB.
SNTP – Simple Network Time Protocol (SNTP) is a protocol for synchronizing the clocks of computer systems over packet switched, variable-latency data networks. It is a simpler and less accurate version of the Network Time Protocol (NTP).
Software Trigger – A programmed event that triggers an event such as data acquisition.
Sourcing Output (PNP) – Outputs that source or push current through the load. The common connection to the load is 0 VDC, this means sourcing outputs require the load to be energized by a current that flows from 24 VDC through the PNP switch, through the load to the 0 VDC line.
SPDT – Single-Pole Double Throw. A property of a switch in which one terminal can be connected to one of two other terminals.
SSH – Simultaneous Sampling and Hold. A property of a system in which each input or output channel is digitized or updated at the same instant.
Static Electricity – A stationary electric charge, typically produced by friction, causes sparks or crackling or attracts dust or hair.
Static Induction – See Electrostatic Induction.
Storage – The process of storing data that has been collected from sensors and other sources. This data can be stored in various formats, such as files, databases, or cloud-based storage systems, and can be used for analysis and reporting. Storage also plays an important role in data security, as it allows for data to be backed up and secured in case of any unforeseen events. Additionally, data storage systems can be used to monitor data trends over time, allowing for the identification of patterns and anomalies that can be used to improve data acquisition processes.
Strain – Is detected using a strain gage with dimensions of strain in μm/m, that means extension related to the grid length of the strain gage. In practical use, the strain is in the range of ±2000 μm/m. A strain, which is too high could damage the material.
Strain Gage – A device that is used to measure the strain of an object. The most common type consists of an insulating flexible backing that contains a metallic foil pattern. The gage attaches to the object using the proper adhesive. The metallic foil deforms as the object deforms causing an electrical resistance to change. This resistance change is measured using a Wheatstone bridge; A sensor whose resistance is a function of the applied force.
Subnet – A shortcut for subnetwork, is a logically visible, distinctly addressed part of a single Internet Protocol network. Subnetting breaks a network into smaller realms that may use existing address space more efficiently and when physically separated, may prevent excessive rates of Ethernet packet collision in a larger network.
Subroutine – A set of software instructions executed by a single line of code that may have input and/or output parameters.
Successive-Approximation ADC – An ADC that sequentially compares a series of binary-weighted values with an analog input to produce an output digital word in n steps, where n is the bit resolution of the ADC.
Sync. Sample Frequency – If you are using several modules on various interfaces (UARTs), which operate at different measuring rates, then this parameter can ensure that those values transferred over the UART with a slow measuring rate are synchronized to the time points which a measurement is also present that has been acquired with a fast measuring rate.
Synchronous – A property of a function that begins an operation and returns only when the operation is complete.
System Noise – A measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded.
System Synchronization Time – Defines in which intervals the system counters are synchronized.
Talker – A device on the General Purpose Interface Bus (GPIB) that sends data to the Listener on the GPIB.
TCP/IP – The Internet Protocol Suite, is the set of communication protocols used for the Internet and other similar networks. TCP is the Transmission Control Protocol and IP is the Internet Protocol, which were the first networking protocols defined in this standard. The protocol suite has four abstraction layers, each with its own protocols: link layer, internet layer, transport layer, and application layer; The Internet Protocol (IP) for the low-level service of taking data and packaging of components, and Transmission Control Protocol (TCP) for high-reliability data transmissions.
TEDS – Transducer Electronic Data Sheet, is a standardized method of storing transducer identification, calibration, correction data, and any manufacturer related information. A TEDS sensor provides an interface that maintains the analog signal (voltage, current, impedance, bridge, etc.) and adds a digital interface to transmit the TEDS information. There are two types, a Class 1 and Class 2 TEDS sensor.
- Class 1 TEDS Sensor: The digital signal is shared with the analog signal on the same lines and multiplexed based on the biasing of the sensor. The sensor incorporates the EEPROM and the circuitry for switching (usually a resistor and a diode).
- Class 2 TEDS Sensor: The TEDS EEPROM and analog signal use different lines to transfer data therefore no switching is required.
Temperature – Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. It is measured with a thermometer and is usually expressed in terms of degrees on the Celsius, Fahrenheit, or Kelvin scales. Temperature is a measure of the average kinetic energy of the particles in an object, and is determined by the amount of heat energy transferred from one object to another.
THD – Total harmonic distortion. The ratio of the total rms signal due to harmonic distortion to the overall rms signal, in dB or percent.
THD+N – Signal-to -THD Plus Noise. The ratio in decibels of the overall rms signal to the rms signal of harmonic distortion plus noise introduced.
Thermistor – A semiconductor sensor that exhibits a repeatable change in electrical resistance as a function of temperature. Most thermistors exhibit a negative temperature coefficient.
Thermocouple – A device that consists of two different conductors, usually a metal alloy that produce a voltage, proportional to a temperature difference, between either end of the two conductors. They are widely used as a type of temperature sensor for measurement and control. They are relatively inexpensive, interchangeable, and supplied with standard connectors. Incomparison, they are self powered and require no form of excitation. The downside is accuracy and system errors of less than one degree C is difficult to achieve; A common type of temperature sensor used to convert thermal potential difference to electrical potential difference. More information on thermocouples can be found at the NIST ITS-90 Thermocouple Data-base.
Throughput Rate – The data, measured in bytes/s, for a given continuous operation.
Torque Sensor – Also known as a torque transducer or torquemeter, is a device that is used to measure and record the torque on a rotating system such as engine, transmission, etc. Static torque is relatively easy to measure while dynamic torque can be more difficult (Requires transfer of some effect, electric or magnetic, from the shaft being measured to a static system). These sensors use strain gages applied to a rotating shaft or axle.
Transducer – A device that responds to a physical stimulus (heat, light, sound, pressure, motion, flow, and so on), and produces a corresponding electrical signal.
Transfer Rate – The rate, measured in bytes/s, at which data is moved from source to destination after software initialization and set up operations; the maximum rate at which the hardware can operate.
Tribocharging – Tribocharging is a contact electrification process that enables buildup of static electricity due to touching or rubbing of surfaces in specific combinations of two dissimilar materials.
TTL – is an acronym for Transistor-Transistor Logic. It relies on circuits built from bipolar transistors to achieve switching and maintain logic states. Both the amplifying function and the logic gating function are carried out through transistors, thus the name transistor-transistor logic.
Standard TTL circuits operate with a 5-volt power supply. A TTL input signal is defined as “low” when between 0 V and 0.8 V with respect to the ground terminal, and “high” when between 2 V and VCC (5 V), and if a voltage signal ranging between 0.8 V and 2.0 V is sent into the input of a TTL gate, there is no certain response from the gate and therefore it is considered “uncertain” (precise logic levels vary slightly between sub-types and by temperature). TTL outputs are typically restricted to narrower limits of between 0.0 V and 0.4 V for a “low” and between 2.4 V and VCC for a “high”, providing at least 0.4 V of noise immunity.
UART – (Universal Asynchronous Receiver/Transmitter) Is a piece of hardware that translates data between parallel and serial forms. They are typically part of an integrated circuit for communications between computers and external devices. Data and transmission of such data are configured by external means outside of the actual UART.
Unipolar – A signal range that is always positive (for example, 0 to +10 V).
UPS – Uninterruptible Power Supply (or source). Designed to maintain electrical power to electronic devices in the event of utility power failure.
USB – Universal Serial Bus, is an industry standard developed in the mid 90s that defines cables, connectors, and commuications protocols used in a bus for connection, communication, and power supply between computers and other electronic devices. USB was designed to standardize the connection of computer peripherals, to provide communication and supply of power. Developed as a serial communications standard to replace Serial and Parallel devices.
V – The unit symbol for Volt
Vibration – Data acquisition involving vibration is the process of measuring and analyzing the vibrational characteristics of a system or object. Vibration is typically measured with accelerometers, which measure the acceleration of a physical object in a given direction. The data is then used to analyze the object’s vibration, assess the integrity of the system or object, and diagnose potential issues. This data can be used to identify potential problems with the system or object before they become catastrophic.
Virtual Variable – With virtual variables you can carry out computations, evaluate trigger conditions or carry out assessments. The variables can be outputs like measurements or linked to other variables, measurements, or digital I/Os.
Volatile Memory – Memory that requires power to maintain the stored information. An example is RAM (random access memory), also known as temporary memory. When the power is shut down, the information is lost.
Volt – The unit of measure for electrical potential difference across a conductor.
Voltage – The value of electrical potential difference across a conductor expressed in volts.
Voltage-to-Frequency Converter – A device that converts analog input voltage into a sequence of digital pulses at a frequency proportion-al to the analog input voltage.
WAN – Wide Area Network. A wide area network is typically made up of two or more Local area Networks, or LANs.
Watchdog Timeout – Defines a security level if a digital/analog output of the connected e.bloxx/q.bloxx module are host controlled. If the controller does not communicate with the e.bloxx/q.bloxx module any more the analog/digital output of the module will return to a default value after the defined value. The default value is 5 seconds and can be adjusted in the range of 0-2100 seconds.
Web portal – A web portal is a specially designed website that brings information from diverse sources, like emails, online forums and search engines, together in a uniform way. Usually, each information source gets its dedicated area on the page for displaying information (a portlet); often, the user can configure which ones to display. Variants of portals include mashups and intranet “dashboards” for executives and managers. The extent to which content is displayed in a “uniform way” may depend on the intended user and the intended purpose, as well as the diversity of the content. Very often design emphasis is on a certain “metaphor” for configuring and customizing the presentation of the content (e.g., a dashboard or map) and the chosen implementation framework or code libraries. In addition, the role of the user in an organization may determine which content can be added to the portal or deleted from the portal configuration.
A portal may use a search engine’s application programming interface (API) to permit users to search intranet content as opposed to extranet content by restricting which domains may be searched. Apart from this common search engines feature, web portals may offer other services such as e-mail, news, stock quotes, information from databases and even entertainment content. Portals provide a way for enterprises and organizations to provide a consistent “look and feel” with access control and procedures for multiple applications and databases, which otherwise would have been different web entities at various URLs. The features available may be restricted by whether access is by an authorized and authenticated user (employee, member) or an anonymous website visitor.
Weight – Weight is a measurement of the amount of force applied to an object. Weight is typically measured in newtons (N), kilograms (kg), or pounds (lb).
Wheatstone Bridge – A network of four resistors that allows a data acquisition system to measure very small changes in the resistance of sensors such as strain gages, load cells, and similar measurement devices which change resistance in response to some external stimulus.
Wi-Fi – Wireless-Fidelity. Wi-Fi is a brand of high-frequency wireless local area network (WLAN) licensed by the Wi-Fi Alliance trade group, and is based on the IEEE 802.11 specifications.
x-axis – The horizontal axis on a graph perpendicular to the y-axis on a graph
y-axis – The vertical axis perpendicular to the x-axis on a graph
z-axis – The third axis in a three-dimensional coordinate graph perpendicular to the plane defined by the x and y axes.
Zero-Overhead Looping – The ability of a high-performance processor to re – peat instructions without requiring time to branch to the beginning of the instructions.