Glossaire des termes
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).
ADC – An Analog to Digital Converter, is a device that 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.
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.
ASCII – The American Standard Code for Information Interchange is a chracter-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 processedd, the other 95 are printable characters (including space).
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.
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.
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.
Bit – The basic unit of information storage, a single binary digit that is either 0 or 1.
Bridge Factor – This indicates how many active strain gauges are in the Wheatstone bridge. At quarter bridge applications, usually there is only one strain gauge in the bridge, so the factor is 1. Therefore the factor is 2 when using 2 active gauges.
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.
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).
Circular Buffer – A circular buffer is available on a Gantner Instruments test 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.
Cold Junction Compensation (CJC) – 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.
Common Mode Rejection Ratio – Abbreviated CMRR, is an important measure for strain gauge amplifiers. A strain gauge 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.
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.
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.
Data Length – Indicates the set data format. 1 Byte = Boolean or 2 Bytes = Integer.
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.
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.
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.
EPROM – Erasable Programmable Read Only Memory, is a type of memory chip that retains its data when its power supply is switched off (non-volatile). Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light.
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.
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.
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).
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.
Floatingpoint – 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.
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 gauges. It provides the highest sensitivity, fewest error, produces highest output, and noise being a non-factor. A full bridge contains four strain gauges, 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 gauges in tension and two gauges 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.
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.
Gauge Factor – GF or strain factor of a strain gauge 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.
Half Bridge Circuit – A bridge circuit where only two strain gauges 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 gauges.
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.
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.
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.
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.
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 test controller (i.e. Q.gate or Q.pac) and I/O modules can achieve speeds up to 48 Mbps.
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.
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.
Macro – Is a set of rules that specifies how input sequences should be mapped to output sequences.
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.
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.
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.
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.
Precision – In channel configuration, determines the number of characters after the decimal point. The precision can amount from 0 to (field length – 2).
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.
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.
Quarter Bridge Circuit – This version of a bridge circuit only uses one strain gauge and three bridge completion resistors. This configuration has the smallest output with alot of noise potential.
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.
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.
RS-485 – Is a standard defining the electrical characteristics of drivers and receivers. 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.
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 lienarly proportional to the angular displacement of its input shaft.
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.
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 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.
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).
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.
Strain – Is detected using a strain gauge with dimensions of strain in μm/m, that means extension related to the grid length of the strain gauge. In practical use, the strain is in the range of ±2000 μm/m. A strain, which is too high could damage the material.
Strain Gauge – 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 gauge attachs 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.
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.
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.
System Synchronization Time – Defines in which intervals the system counters are synchronized.
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.
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.
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.
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 gauges applied to a rotating shaft or axle.
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.
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.
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.
Watchdog Timeout – Defines a security level if a digital/analog output of the connected e.bloxx/q.bloxx module are host controlled. If the test 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.