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Chapter 4

Theory of Operation

NI PXI-4220 User Manual

4-26

ni.com

Offset Null Compensation

The NI PXI-4220 provides offset null compensation to adjust signal 
voltages to proper levels when the strain gauge or bridge sensor is at rest 
(unstrained). For most sensors offset null compensation is used to remove 
an initial voltage offset from the Wheatstone bridge. Many strain gauge 
signal conditioning devices use a manually adjusted multiturn screw 
potentiometer for offset null compensation. In the NI PXI-4220, offset 
null compensation is performed electronically using software-controlled 
electronic potentiometers. 

Two offset null compensation potentiometers are used, one for coarse 
adjustments and the other for fine adjustments. The sum of the 
two potentiometer signals is added to the analog input path to adjust the 
signal voltage to remove the offset, which nulls the strain-gauge channel. 
The voltage input to the potentiometers is a voltage proportional to the 
excitation voltage setting. Therefore, if the excitation voltage changes by 
a small amount due to changes such as temperature and sensor loading, 
the correction signal produced by the potentiometers changes by the same 
amount and the offset null compensation is maintained.

The offset null compensation potentiometers are controlled digitally using 
control codes. The control codes of the potentiometers are set in software 
using integer values. The coarse potentiometer ranges from 0 to 127 and the 
fine potentiometer from 0 to 4,095. The span of correction (the voltage 
nulling range) for each potentiometer depends on the channel gain setting. 
Table 4-2 summarizes the nulling range and scale of the control codes.

In most cases, you do not explicitly set the offset null compensation 
potentiometers, but instead allow the NI-DAQmx driver software to 
automatically adjust them for you. This can be done in MAX.

Table 4-2.  

Control Codes for Coarse and Fine Null Potentiometers

Offset Null 

Compensation 

Potentiometer

Range 

(Integer Values)

Mid-Scale

Module Channel 

Gain Settings

Approximate 

Correction Span 

at Analog Input

Coarse

0 to 127

62

≥

20

V

EX

/10

<20

2 

×

 

V

EX

Fine

0 to 4095

2047

≥

20

V

EX

/364

<20

V

EX

/18

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Содержание PXI-4220

Страница 1: ...erutilized and idle equipment along with credit for buybacks and trade ins Custom engineering so your equipment works exactly as you specify Critical and expedited services Leasing Rentals Demos In st...

Страница 2: ...PXI NI PXI 4220 User Manual NI PXI 4220 User Manual May 2005 373530B 01 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 3: ...ia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210 311 210 Russia 7 095 783 68 51 Singapore 1800...

Страница 4: ...isuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not...

Страница 5: ...cautions to avoid electrical shock When symbol is marked on a product it denotes a component that may be hot Touching this component may result in bodily injury bold Bold text denotes items that you m...

Страница 6: ...9 Full Bridge Type II 2 10 Full Bridge Type III 2 11 Remote Sense 2 12 Chapter 3 Configuring and Testing Verifying and Self Testing Using Device Test Panels 3 1 NI PXI 4220 Software Configurable Sett...

Страница 7: ...e I 4 12 Full Bridge Type II 4 14 Full Bridge Type III 4 16 NI PXI 4220 Theory of Operation 4 18 Bridge Configuration and Completion 4 21 Excitation 4 21 Remote Sense 4 22 Gain Input Range 4 24 Filter...

Страница 8: ...oping an Application Using LabVIEW 5 8 Using a DAQmx Channel Property Node in LabVIEW 5 10 Synchronization and Triggering 5 12 Synchronizing the NI PXI 4220 5 12 Synchronizing the NI PXI 4220 Using La...

Страница 9: ...idge Type I Measuring Axial and Bending Strain 4 8 Figure 4 7 Half Bridge Type I Circuit Diagram 4 9 Figure 4 8 Half Bridge Type II Rejecting Axial and Measuring Bending Strain 4 10 Figure 4 9 Half Br...

Страница 10: ...ignal Timing B 8 Figure B 11 AI SAMPLE CLK TIMEBASE Signal Timing B 9 Figure B 12 AI HOLD COMPLETE Signal Timing B 10 Figure C 1 Injector Ejector Handle Position Before Device Removal C 2 Tables Table...

Страница 11: ...he NI DAQmx DAQ Assistant specifically the Strain Gage Calibration wizard to easily perform offset null compensation and shunt calibration The NI PXI 4220 is a two channel module for interfacing to Wh...

Страница 12: ...up and use the NI PXI 4220 you need the following Hardware NI PXI 4220 device PXI chassis Sensors as required by your application Software NI DAQ 7 0 or later One of the following LabVIEW Measurement...

Страница 13: ...includes LabVIEW Measurement Studio and LabWindows CVI After you set up the hardware system use either your application software documentation or the NI DAQmx documentation to help you write your appl...

Страница 14: ...unpack install and configure the NI PXI 4220 in a PXI chassis LED Pattern Descriptions The following LEDs on the NI PXI 4220 front panel confirm the system is functioning properly The ACCESS LED is no...

Страница 15: ...s well as full bridge sensors such as load force torque and pressure sensors It also discusses connecting leads for remote sensing Refer to Chapter 4 Theory of Operation for a discussion of strain gau...

Страница 16: ...han 10 V can damage the device Figure 2 2 shows the pin signal assignments for each of the NI PXI 4220 D SUB connectors Refer to Figure 2 2 when constructing D SUB connection leads to ensure the signa...

Страница 17: ...ompletion Pin 2 P0 Pin 3 RS0 Pin 6 S0 Pin 1 S0 Pin 7 P0 Pin 5 SCCOM Pin 4 QTR Shunt Cal A SCB0 Shunt Cal B Shunt Cal A Quarter Bridge Completion Pin 8 RS0 Pin 9 QTR Shunt Cal B A B R1 R2 Vex 2 Vex 2 C...

Страница 18: ...it wiring diagram Refer to the Quarter Bridge Type I section of Chapter 4 Theory of Operation for more information Note If you have a two wire strain gauge element connect the active element leads to...

Страница 19: ...This configuration uses the Shunt Cal A switch for shunt calibration Note The value of the quarter bridge completion resistor dummy resistor must equal the nominal resistance of the strain gauge NI re...

Страница 20: ...ridge completion resistors R3 is the quarter bridge temperature sensing element dummy gauge R4 is the active element measuring tensile strain VEX is the excitation voltage RL is the lead resistance VC...

Страница 21: ...Bridge Type I Circuit Diagram The following symbols apply to the circuit diagram and equations R1 and R2 are half bridge completion resistors R3 is an active element measuring compression from Poisson...

Страница 22: ...e Type II Circuit Diagram The following symbols apply to the circuit diagram and equations R1 and R2 are half bridge completion resistors R3 is an active element measuring compressive strain R4 is an...

Страница 23: ...gram The following symbols apply to the circuit diagram and equations R1 is an active element measuring compressive strain R2 is an active element measuring tensile strain R3 is an active element meas...

Страница 24: ...symbols apply to the circuit diagram and equations R1 is an active element measuring compressive Poisson effect R2 is an active element measuring tensile Poisson effect R3 is an active element measur...

Страница 25: ...Type III Circuit Diagram The following symbols apply to the circuit diagram and equations R1 is an active element measuring compressive Poisson effect R2 is an active element measuring tensile strain...

Страница 26: ...and equations R1 R2 R3 and R4 are the transducer bridge elements VCH is the measured voltage VEX is the excitation voltage RL is the lead resistance VRSENSE is the measured bridge excitation Note Rem...

Страница 27: ...nals properly The test panels allow you to measure the signal connected to the NI PXI 4220 directly as well as configure some of the properties of your measurement To open the NI PXI 4220 device test...

Страница 28: ...n and Completion Bridge configuration is a software configurable setting that allows you to connect quarter half or full bridge sensors configurations Refer to Chapter 4 Theory of Operation for more i...

Страница 29: ...should determine the appropriate gain using the input signal voltage range and the full scale limits of the NI PXI 4220 signal conditioning output signal Offset Null Compensation Potentiometers Coars...

Страница 30: ...ations that might require SS H include vibration measurements and phase difference measurements You can disable this setting through your application if you require scan rates beyond the maximum allow...

Страница 31: ...NI DAQmx Task or NI DAQmx Global Channel and functions in your application The default bridge configuration for NI DAQmx is full bridge Voltage Excitation set either through NI DAQmx Task or NI DAQmx...

Страница 32: ...NI DAQmx Task or NI DAQmx Global Channel and click Next 4 Select Analog Input and then select Strain 5 If you are creating a task keep the Create New Local Channels selected and select the channels to...

Страница 33: ...Reset Data to reset the values to default Click Calibrate to calibrate the strain channel s When you have completed calibrating the strain channel s click Finish Note For offset null compensation and...

Страница 34: ...the auto zero mode and lowpass filter cutoff frequency 10 If you are applying custom scaling select Create New from the Custom Scaling drop down and follow the wizard instructions 11 If you are creati...

Страница 35: ...11 Click the Start button 12 After you have completed verifying the channels click the Stop button You have now verified the NI PXI 4220 configuration and signal connection Note For more information a...

Страница 36: ...agram Figure 4 1 Basic Wheatstone Bridge Circuit Diagram The Wheatstone bridge is the electrical equivalent of two parallel voltage divider circuits R1 and R2 compose one voltage divider circuit and R...

Страница 37: ...upported strain gauge configuration types measure axial strain bending strain or both While you can use some similar configuration types to measure torsional strain NI software scaling does not suppor...

Страница 38: ...ge VEX is the excitation voltage Vr is the voltage ratio that is used in the voltage to strain conversion equations and is defined by the following equation Software Scaling and Equations Once you hav...

Страница 39: ...Type I Measuring Axial and Bending Strain A quarter bridge type I has the following characteristics A single active strain gauge element is mounted in the principle direction of axial or bending stra...

Страница 40: ...n STC number that corresponds to the thermal expansion coefficient of the material under test STC gauges have a temperature sensitivity that counteracts the thermal expansion coefficient of the test s...

Страница 41: ...gram Figure 4 4 Quarter Bridge Type II Measuring Axial and Bending Strain A quarter bridge type II has the following characteristics One active strain gauge element and one passive temperature sensing...

Страница 42: ...in VEX is the excitation voltage RL is the lead resistance VCH is the voltage measured To convert voltage readings to strain units use the following equation where Rg is the nominal gauge resistance R...

Страница 43: ...d resistance of 0 25 Half Bridge Type I This section provides information about the half bridge strain gauge configuration type I The half bridge type I measures either axial or bending strain Figure...

Страница 44: ...element measuring compression from Poisson effect R4 is the active strain gauge element measuring tensile strain VEX is the excitation voltage RL is the lead resistance VCH is the voltage measured To...

Страница 45: ...f the wiring if shunt calibration is performed or if lead length is very short 10 ft depending on the wire gauge For example 10 ft of 24 AWG copper wire has a lead resistance of 0 25 Half Bridge Type...

Страница 46: ...rain gauge element measuring compressive strain R4 is the active strain gauge element measuring tensile strain VEX is the excitation voltage RL is the lead resistance VCH is the voltage measured To co...

Страница 47: ...ot directly short SCA pin 4 or SCCOM pin 5 inside your connector unless the strain gauge leads are short and have minimal lead resistance You can neglect lead resistance RL of the wiring if shunt cali...

Страница 48: ...emperature variation Compensates for lead resistance Sensitivity at 1000 is 2 0 mVout VEX input Figure 4 11 Full Bridge Type I Circuit Diagram The following symbols apply to the circuit diagram and eq...

Страница 49: ...and the shunt calibration pins SCA pin 4 and SCCOM pin 5 Do not directly short SCA pin 4 or SCCOM pin 5 inside your connector unless the strain gauge leads are short and have minimal lead resistance F...

Страница 50: ...ture variation Compensates for the aggregate effect on the principle strain measurement due to the Poisson s ratio of the specimen material Compensates for lead resistance Sensitivity at 1000 is 1 3 m...

Страница 51: ...er corresponding to the material type of the test specimen As shown in Figure 2 9 Full Bridge Type II Circuit Diagram for greatest calibration accuracy use separate wires between the bridge and the sh...

Страница 52: ...one side of the strain specimen top the other on the opposite side bottom Compensates for specimen temperature variation Rejects bending strain Compensates for the aggregate effect on the principle s...

Страница 53: ...and R1 and R3 are positioned transverse to the beam axis and on opposite sides of the beam The nominal values of R1 R2 R3 and R4 equal Rg Gauges need not have an STC number corresponding to the materi...

Страница 54: ...e EEPROM EEPROM ADC FIFO A D Converter AI Control IRQ DMA NI PGA Analog Mode Multiplexer Voltage Reference Calibration DACs Control Address Data PXI Connector RTSI Data Cal MUX Temperature Sensor Sign...

Страница 55: ...m both channels You cannot enable or disable SS H on a per channel basis Disabling SS H results in higher maximum sample rates Disabling SS H introduces a small offset voltage You can compensate for t...

Страница 56: ...ected to QTR SCBX pin 9 as shown in Figure 2 4 Quarter Bridge I Circuit Diagram Make sure that the value of the precision quarter bridge completion resistor exactly matches the nominal gauge resistanc...

Страница 57: ...o chassis ground Note Chassis ground is at the same potential as earth ground when the PXI chassis is plugged into a standard 3 prong AC outlet If pin PX pin 7 is connected to earth ground the excitat...

Страница 58: ...e set RL to zero in the MAX configuration of the channel and in your application equations for measured strain If you leave the remote sense pin unconnected internal 1 k resistors provide feedback to...

Страница 59: ...the gain of the first stage is set to 20 so that the noise and offset drift of later stages is small in comparison to this stage The instrumentation amplifier stage uses operational amplifiers with ve...

Страница 60: ...20 provides two filtering stages with an overall response of a four pole Butterworth filter You can control the cutoff frequency of the filter through software You can choose 10 Hz 100 Hz 1 kHz 10 kHz...

Страница 61: ...ltage changes by a small amount due to changes such as temperature and sensor loading the correction signal produced by the potentiometers changes by the same amount and the offset null compensation i...

Страница 62: ...r is then multiplied by each future measurement to obtain highly accurate measurements that are adjusted for any gain errors or discrepancies in the nominal gauge factor Refer to the Configurable Sett...

Страница 63: ...hronized samples of all channels with negligible skew time between channels SS H signal conditioning is performed on the NI PXI 4220 with T H circuitry The outputs of the T H amplifiers follow their i...

Страница 64: ...r most applications By default the NI PXI 4220 has SS H enabled You should only disable SS H if your application does not require simultaneous Hold Line Convert Clock 1 2 3 CH0 CH1 1 HoldTime 2 Max Mi...

Страница 65: ...is preferable because it rejects not only common mode voltages and ground loop induced errors but also the noise picked up in the environment to a certain degree Common Mode Rejection Ratio The abili...

Страница 66: ...cations such as internal hardware timing or multiple point acquisitions equivalent time sampling and seamless changing of the sampling rate The NI PXI 4220 uses the PXI trigger bus to easily synchroni...

Страница 67: ...en timing signal Any timing signal can use the PFI0 pin as an input and multiple timing signals can simultaneously use the same PFI This flexible routing scheme reduces the need to change physical con...

Страница 68: ...vice programmed to receive this timebase signal This clock source whether local or from the PXI trigger bus is used directly by the device as the primary frequency source The default configuration use...

Страница 69: ...the timing signals available on the PXI trigger bus For more detailed timing signal information refer to Appendix B Timing Signal Information PXI Bus Connector Switch RTSI Switch PXI Trigger 7 PXI Tr...

Страница 70: ...creates the reference point between the pretrigger samples and the posttrigger samples Input Input Output AI SAMP CLK Input Output This clock controls the time interval between samples Each time the...

Страница 71: ...configure and use NI DAQmx to control the NI PXI 4220 in LabVIEW LabVIEW provides greater flexibility and access to more settings than MAX but you can use LabVIEW in conjunction with MAX to quickly cr...

Страница 72: ...Task Using DAQ Assistant No Yes No Yes Configure Channels Further Configure Channels Start Measurement Read Measurement Clear Task Continue Sampling Stop Measurement Yes No Perform Offset Null Compen...

Страница 73: ...or that requires complex scaling or when many properties differ between channels in the same task If you are using an ADE other than an NI ADE or if you want to explicitly create and configure a task...

Страница 74: ...requested sample rate You also can select advanced features such as clock settings that specify an external clock source internal routing of the clock source or select the active edge of the clock si...

Страница 75: ...o place the shunt calibration resistor across one arm of the bridge Analog Input General Properties Signal Conditioning Excitation Value AI Excit Val Specifies the amount of excitation in volts Analog...

Страница 76: ...performed during Analog Input General Properties Signal Conditioning Bridge Initial Bridge Voltage AI Bridge InitialVoltage Specifies in volts the output voltage of the bridge in the unloaded conditio...

Страница 77: ...ting for information about shunt calibration when in MAX To manually perform shunt calibration refer to the Shunt Calibration section of Chapter 4 Theory of Operation Acquiring Analyzing and Presentin...

Страница 78: ...cation Using LabVIEW This section describes in more detail the steps shown in the typical program flowchart in Figure 5 1 such as how to create a task in LabVIEW and how to configure the channels of t...

Страница 79: ...nfigured the channels in your task using the DAQ Assistant Any channel modifications made with a channel property node are not saved in the task in the DAQ Assistant they are only available for the pr...

Страница 80: ...yze Data Some examples of data analysis include filtering scaling harmonic analysis or level checking Some data analysis tools are located on the Functions Signal Analysis subpalette and on the Functi...

Страница 81: ...nge To and select Write Read or Default Value 8 After you have added the property to the property node right click the terminal to change the attributes of the property add a control constant or indic...

Страница 82: ...master NI PXI 4220 exports the shared timing signals through the PXI bus to the slave devices Each NI PXI 4220 contains a DAQ STC chip and is capable of generating a hardware sample clock based on it...

Страница 83: ...Task Create Slave Channels Set Slave to Use Timebase from Master Start Slave Measurement s Start Master Measurement Configure Master Channel Continue Sampling Yes No Clear Master Task Clear Slave Task...

Страница 84: ...ge by default To change to a strain gauge channel click AI Voltage and select Analog Input Strain Strain Gage Configure Master Channels Use a DAQmx Channel Property Node Refer to the Using a DAQmx Cha...

Страница 85: ...se Src and MasterTimebase Rate to the values retrieved from the master task in the Get Master Timebase Source and Rate from Master Task step Configure Slave Triggering DAQmx Trigger vi Start Digital E...

Страница 86: ...high precision reference voltage NI driver software disconnects the channel inputs from the front signal connector and reconnects the inputs to ground or to an onboard reference when performing an in...

Страница 87: ...rating the System You should perform offset null compensation or shunt calibration on transducers in your system to improve accuracy This is considered system or end to end calibration Offset Null Com...

Страница 88: ...ngs X1 to X1000 with the following gain settings 1 1 15 1 3 1 5 1 8 2 2 2 2 4 2 7 3 1 3 6 4 2 5 6 6 5 7 5 8 7 10 11 5 13 15 18 20 22 24 27 31 36 42 56 65 75 87 100 115 130 150 180 200 220 240 270 310...

Страница 89: ...V 180 0 mV 42 0 1 75 100 10 0 0300 5 00 265 V 100 0 mV 100 0 1 50 50 5 0 0 0300 5 00 155 V 50 0 mV 200 0 1 50 25 2 5 0 0300 5 00 103 V 18 0 mV 420 0 1 50 10 1 0 0 0300 5 00 69 V 10 0 mV 1000 0 1 50 10...

Страница 90: ...missing codes 16 bits guaranteed Calibration Recommended warm up time 15 minutes External calibration interval 1 year Onboard calibration reference Level 5 000 V 1 mV actual value stored in EEPROM Tem...

Страница 91: ...Hz filter 40 Vpp Noise RTI gain 200 0 1 to 10 Hz 1 5 Vpp Spot noise RTI gain 200 1000 Hz 16nV Filter Characteristics Lowpass filter type 4 pole Butterworth 24 dB octave rolloff Lowpass filter settings...

Страница 92: ...resolution 80 000 microstrain null compensation range 4 microstrain resolution for quarter bridge GF 2 0 Excitation Type Constant voltage Settings 0 0 to 10 0 V in 1 024 equally spaced increments Erro...

Страница 93: ...rt and stop trigger gate clock Source PFI0 TRIG1 front SMB connector PXI_Trig 0 5 PXI_Star PXI trigger bus 1 Half bridge completion is performed inside the module and configured under software control...

Страница 94: ...le transfer demand transfer Configuration memory size 512 words Bus interface Master slave Power requirements 1 A at 5 VDC 5 Physical Dimensions not including connectors 16 0 10 0 2 0 cm 6 3 3 9 0 79...

Страница 95: ...C 61010 1 EN 61010 1 UL 61010 1 CAN CSA C22 2 No 61010 1 Note For UL and other safety certifications refer to the product label or visit ni com certification search by model number or product line and...

Страница 96: ...afety 73 23 EEC Electromagnetic Compatibility Directive EMC 89 336 EEC Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain t...

Страница 97: ...he device I O connector for applications requiring alternative wiring As an input each PFI signal can be individually configured for edge or level detection and polarity selection You can use the pola...

Страница 98: ...typical posttriggered sequence Figure B 1 Typical Posttriggered Sequence Pretriggered DAQ allows you to view data that is acquired before the trigger of interest in addition to data acquired after th...

Страница 99: ...triggered acquisitions Refer to Figures B 1 and B 2 for the relationship of AI START TRIG to the sequence As an output AI START TRIG reflects the action that initiates a sequence even if the acquisiti...

Страница 100: ...scan counter SC indicates the minimum number of scans before AI REF TRIG is recognized After the SC decrements to zero it is loaded with the number of posttrigger scans to acquire while the acquisitio...

Страница 101: ...ernally triggered AI CONV CLK As an output AI SAMP CLK reflects the actual start pulse that initiates a scan even if the starts are externally triggered by another PFI PXI_Trig 0 5 or PXI_Star You hav...

Страница 102: ...hen the onboard SI2 counter reaches zero If you select an external AI CONV CLK the first external pulse after AI SAMP CLK generates a conversion Separate the AI SAMP CLK pulses by at least one scan pe...

Страница 103: ...e as an output on PXI_Trig 0 5 Refer to Figures B 1 and B 2 for the relationship of AI CONV CLK to the sequence As an input AI CONV CLK is configured in edge detection mode You can configure the polar...

Страница 104: ...gated by either the hardware AI PAUSE TRIG signal or the software command register gate AI PAUSE TRIG Signal PFI0 PXI_Trig 0 5 or PXI_Star can externally input the AI PAUSE TRIG signal which is not av...

Страница 105: ...e source for AI SAMPLE CLK TIMEBASE in level detection mode Configure the polarity selection for the pin for either active high or active low The maximum allowed frequency is 20 MHz with a minimum pul...

Страница 106: ...ing edge can clock external analog input multiplexers indicating when the input signal has been sampled and can be removed This signal has a 400 to 500 ns pulse width and is software enabled Figure B...

Страница 107: ...ollowing steps while referring to Figure C 1 1 Power off the PXI chassis Do not remove the NI PXI 4220 device from a chassis that is powered on 2 Rotate the mounting screws that secure the NI PXI 4220...

Страница 108: ...t of installed devices and interfaces The NI PXI 4220 should have a red circle with a white X inside it next to the device to indicate it has been physically removed from the chassis 2 Right click the...

Страница 109: ...do I control the gain excitation voltage filter setting bridge configuration potentiometer settings and shunt calibration switches from LabVIEW The gain of each NI PXI 4220 channel is automatically se...

Страница 110: ...voltage setting should I set on the NI PXI 4220 Even with an external voltage source for the transducers internal excitation voltage is still used by the offset null compensation circuitry inside the...

Страница 111: ...giga 109 Symbols percent positive of or plus negative of or minus per degree ohm A A amperes A D analog to digital AC alternating current ADC analog to digital converter an electronic device often an...

Страница 112: ...ignal range that includes both positive and negative values for example 5 to 5 V breakdown voltage the voltage high enough to cause breakdown of optical isolation semiconductors or dielectric material...

Страница 113: ...nstrumentation amplifier inputs with respect to amplifier ground counter timer a circuit that counts external pulses or clock pulses timing CTR counter D D A digital to analog DAC digital to analog co...

Страница 114: ...y on the bus while the processor does something else DMA is the fastest method of transferring data to from computer memory DNL differential nonlinearity a measure in least significant bit of the wors...

Страница 115: ...om the ideal gain grounded measurement system See referenced single ended configuration H h hour Hz hertz the number of scans read or updates written per second I I O input output the transfer of data...

Страница 116: ...CLK K k kilo the standard metric prefix for 1 000 or 103 used with units of measure such as volts hertz and meters kS 1 000 samples L LabVIEW Laboratory Virtual Instrument Engineering Workbench a pro...

Страница 117: ...g measurement devices 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...

Страница 118: ...gle ended configuration RSE all measurements are made with respect to a common reference measurement system or ground also called a grounded measurement system relative accuracy a measure in LSB of th...

Страница 119: ...up For example one pulse from the scan clock produces one scan which acquires one new sample from every analog input channel in the group scan clock the clock controlling the time interval between sca...

Страница 120: ...lts VCC positive supply voltage VDC volts direct current VI virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic sta...

Страница 121: ...tions D 1 configuration settings excitation level 3 2 filter bandwidth 3 3 gain 3 3 4 24 null potentiometers 3 3 conventions used in the manual iv CONVERT signal See also PFI2 CONVERT signal DAQ timin...

Страница 122: ...pattern descriptions 1 4 M Measurement Automation Explorer MAX removing NI PXI 4220 C 2 measurements calibrating PXI 4220 5 16 strain gauge connections full bridge configuration I 2 9 4 12 full bridg...

Страница 123: ...4 27 Q quarter bridge configuration I 2 4 4 4 quarter bridge configuration II 2 6 4 6 questions and answers D 1 R regulatory compliance specifications A 9 remote sense 2 12 removing NI PXI 4220 from M...

Страница 124: ...of operation block diagram 4 19 excitation 4 21 null compensation 4 26 shunt calibration 4 27 timing connections DAQ timing connections AIGATE signal B 8 CONVERT signal B 7 SCANCLK signal B 10 SISOUR...

Страница 125: ...uipment Have surplus equipment taking up shelf space We ll give it a new home Learn more Visit us at artisantg com for more info on price quotes drivers technical specifications manuals and documentat...

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