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NI PXI-4220 User Manual

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  • Page 1 (217) 352-9330 | Click HERE Find the National Instruments PXI-4220 at our website:...
  • Page 2 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...
  • Page 3 For further support information, refer to the Signal Conditioning Technical Support Information document. To comment on National Instruments documentation, refer to the National Instruments Web site at ni.com/info and enter the info code feedback. © 2003–2005 National Instruments Corporation. All rights reserved.
  • Page 4 Warranty The NI PXI-4220 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period.
  • Page 5 Conventions The following conventions are used in this manual: <> Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, DIO<3..0>. » The » symbol leads you through nested menu items and dialog box options to a final action.

  • Page 6: Table Of Contents

    Chapter 1 About the NI PXI-4220 What You Need to Get Started ..................1-2 National Instruments Documentation ................1-3 Installing the Application Software, NI-DAQ, and the DAQ Device ......1-3 Installing the NI PXI-4220 ....................1-4 LED Pattern Descriptions ....................1-4 Chapter 2 Connecting Signals Connecting Bridge Sensor Signals to the NI PXI-4220 ..........2-1...
  • Page 7 Contents Verifying the Signal ...................... 3-8 Verifying the Signal in NI-DAQmx Using a Task or Global Channel ... 3-8 Chapter 4 Theory of Operation Strain Gauge Theory...................... 4-1 Wheatstone Bridges ..................4-1 Strain Gauges ....................4-2 Acronyms, Formulas, and Variable Definitions ..........4-2 Software Scaling and Equations ..............
  • Page 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 LabVIEW ......5-14 Other Application Documentation and Material ............5-15 Calibrating the NI PXI-4220..................5-16 Calibrating the NI PXI-4220 ................5-16 Internal Calibration Procedure ............5-16...
  • Page 9 Glossary Index Figures Figure 2-1. NI PXI-4220 Front Label..............2-2 Figure 2-2. PXI-4220 Front Connector and General Circuit Diagram ....2-3 Figure 2-3. Socketed Resistor Locations ..............2-4 Figure 2-4. Quarter-Bridge I Circuit Diagram............2-5 Figure 2-5. Quarter-Bridge II Circuit Diagram ............2-6 Figure 2-6.
  • Page 10 Table 5-1. NI-DAQmx Properties ................5-4 Table 5-2. Programming a Task in LabVIEW............5-8 Table 5-3. Synchronizing the NI PXI-4220 Using LabVIEW........5-14 Table A-1. Maximum Sampling Rates ..............A-1 © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 11: About The Ni Pxi-4220

    This chapter provides an introduction to the NI PXI-4220 device and its installation. The NI PXI-4220 is part of the SC Series of data acquisition (DAQ) devices with integrated signal conditioning. The SC Series reduces measurement setup and configuration complexity by integrating signal conditioning and DAQ on the same product.

  • Page 12: What You Need To Get Started

    You can configure most settings on a per-channel basis through software. The NI PXI-4220 is configured using Measurement & Automation Explorer (MAX) or through function calls to NI-DAQmx. What You Need to Get Started To set up and use the NI PXI-4220, you need the following: ❑ Hardware –...

  • Page 13: National Instruments Documentation

    NI-DAQ 7.0 or later is required to configure and program the NI PXI-4220 device. If you do not have NI-DAQ 7.0 or later, you can either contact an NI sales representative to request it on a CD or download the it from ni.com...

  • Page 14: Installing The Ni Pxi-4220

    Refer to the DAQ Quick Start Guide to 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 normally green and blinks yellow for a minimum of 100 ms during the NI PXI-4220 configuration.

  • Page 15: Connecting Signals

    Refer to the Read Me First: Safety and Radio-Frequency Interference document Caution before removing equipment covers or connecting/disconnecting any signal wires. Figure 2-1 shows the NI PXI-4220 front label, including the location of the D-SUB connectors and PFI0/CAL SMB connector. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ...

  • Page 16: Figure 2-1. Ni Pxi-4220 Front Label

    Caution only. Voltages greater than ±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 signal wires are routed correctly. In the electrical connection diagram, each signal connection node is labeled with a pin number to indicate which pin carries the signal.

  • Page 17: Figure 2-2. Pxi-4220 Front Connector And General Circuit Diagram

    SCB0 Signal– (S–) Shunt Calibration Switches Figure 2-2. PXI-4220 Front Connector and General Circuit Diagram Note Refer to Figure 2-3 for quarter-bridge and shunt cal completion resistor locations. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 18: Quarter-Bridge Type I

    Chapter 2 Connecting Signals Figure 2-3 shows the location of the socketed NI PXI-4220 resistors. 1 R4 (Shunt Cal B CH 0) 4 R2 (Quarter-Bridge Completion CH1) 2 R1 (Shunt Cal A CH 0) 5 R6 (Shunt Cal B CH 1)

  • Page 19: Figure 2-4. Quarter-Bridge I Circuit Diagram

    The value of the quarter-bridge completion resistor (dummy resistor) must equal the nominal resistance of the strain gauge. NI recommends using a 0.1% precision resistor. If a less precise resistor is used, offset null compensation calibration is not as accurate.

  • Page 20: Quarter-Bridge Type Ii

    I. For more information, refer to the Quarter-Bridge Type II Half-Bridge Type I sections of Chapter 4, Theory of Operation. NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 21: Half-Bridge Type I

    • is the lead resistance. • is the voltage measured. • is shunt calibration resistor A. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 22: Half-Bridge Type Ii

    (+ε). • is the excitation voltage. • is the lead resistance. • is the voltage measured. • is shunt calibration resistor A. NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 23: Full-Bridge Type I

    • is the lead resistance. • is the measured voltage. • is shunt calibration resistor A. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 24: Full-Bridge Type Ii

    • is the excitation voltage. • is the lead resistance. • is the measured voltage. • is shunt calibration resistor A. NI PXI-4220 User Manual 2-10 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 25: Full-Bridge Type Iii

    • is the lead resistance. • is the measured voltage. • is shunt calibration resistor A. © National Instruments Corporation 2-11 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 26: Remote Sense

    Chapter 2 Connecting Signals Remote Sense For remote sensing, wire the NI PXI-4220 for remote sense as shown in Figure 2-11. Refer to the Remote Sense section of Chapter 4, Theory of Operation, for more information about remote sensing. Using remote sense...

  • Page 27: Configuring And Testing

    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 panels when in MAX,...

  • Page 28: Ni Pxi-4220 Software-Configurable Settings

    MAX to programmatically perform offset null compensation and shunt calibration. It also describes how to perform configuration of these settings for the NI PXI-4220 in NI-DAQmx. For more information about the relationship between the...

  • Page 29: Filter

    Gain/input range refers to the signal conditioning gain and digitizer input range, software-configurable settings that allow you to choose the appropriate amplification to fully utilize the range of the NI PXI-4220 DAQ circuitry. In most applications, NI-DAQ sets the gain for you determined by the input range.

  • Page 30: Shunt Calibration Switches

    Configurable Settings in MAX Note If you are not using an NI ADE, or if you are using an NI ADE prior to version 7.0 or an unlicensed copy of an NI ADE, additional dialog boxes from the NI License Manager appear allowing you to create a task or global channel in unlicensed mode.

  • Page 31: Ni-Daqmx

    Strain and custom voltage with excitation are the most commonly used NI-DAQmx Task or NI-DAQmx Global Channel types with the NI PXI-4220. Use the Custom Voltage with Excitation NI-DAQmx Task or Global Channel when measuring load, force, torque, pressure or other bridge-based sensors.

  • Page 32: Creating A Strain Global Channel Or Task

    This leaves the shunt calibration resistor disconnected from the circuit. For more information about how to further configure the NI PXI-4220, or how to use Note LabVIEW to configure the device and take measurements, refer to Chapter 5,...

  • Page 33: Creating A Custom Voltage With Excitation Global Channel Or Task

    Configuring and Testing Note For most NI PXI-4220 applications, you should set the autozero mode to None. Autozero is not useful for relative transducers such as strain gauges. Autozero performs a software compensation for offset voltage from the signal conditioning and DAQ circuitry, not the transducer, and is therefore not as accurate as hardware offset null compensation.

  • Page 34: Verifying The Signal

    Verifying the Signal in NI-DAQmx Using a Task or Global Channel You can verify the signals on the NI PXI-4220 using NI-DAQmx by completing the following steps: Click the + next to Data Neighborhood.
  • Page 35 You have now verified the NI PXI-4220 configuration and signal connection. Note For more information about how to further configure the NI PXI-4220, or how to use LabVIEW to configure the module and take measurements, refer to Chapter 5, Developing Your Application.

  • Page 36: Theory Of Operation

    Wheatstone bridge. The Wheatstone bridge configuration is used to measure the small variations in resistance that the sensing elements produce corresponding to physical changes in the specimen. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 37: Strain Gauges

    While you can use some similar configuration types to measure torsional strain, NI software scaling does not support these configuration types. It is possible to use NI products to measure torsional strain, but to properly scale these configuration types you must create a custom scale in MAX or perform scaling in your software application.

  • Page 38: Software Scaling And Equations

    Finally, there are voltage to strain conversion functions included in LabVIEW and NI-DAQmx. In LabVIEW, the conversion function, , is in the Functions»All Convert Strain Gauge Reading.vi Functions»NI Measurements»Data Acquisition»Signal Conditioning...

  • Page 39: Quarter-Bridge Type I

    The following symbols apply to the circuit diagram and equations: • and R are half-bridge completion resistors. • is the quarter-bridge completion resistor (dummy resistor). NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 40 GF 1 The value of the quarter-bridge completion resistor (dummy resistor) must equal the nominal resistance of the strain gauge. NI recommends using a 0.1% precision resistor. If a less precise resistor is used, offset null compensation calibration is not as accurate.

  • Page 41: Quarter-Bridge Type Ii

    NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 42: Figure 4-5. Quarter-Bridge Type Ii Circuit Diagram

    The dummy gauge temperature must closely track the temperature of the active gauge. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 43: Half-Bridge Type I

    (perpendicular) to the principal axis of strain. • Completion resistors provide half-bridge completion. • Sensitive to both axial and bending strain. • Compensates for specimen temperature variation. NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 44: Figure 4-7. Half-Bridge Type I Circuit Diagram

    To simulate the effect on strain of applying a shunt resistor across R use the following equation: – ε ------------------------------------------------------------- ν ) 2U ν 1 GF 1 – – © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 45: Half-Bridge Type Ii

    (top), and the other is mounted in the direction of bending strain on the opposite side (bottom). • Completion resistors provide half bridge completion. NI PXI-4220 User Manual 4-10 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 46: Figure 4-9. Half-Bridge Type Ii Circuit Diagram

    To simulate the effect on strain of applying a shunt resistor across R use the following equation: – ε ---------- © National Instruments Corporation 4-11 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 47: Full-Bridge Type I

    (+ ) (– ) (+ ) (– ) Bending Axial Figure 4-10. Full-Bridge Type I Rejecting Axial and Measuring Bending Strain NI PXI-4220 User Manual 4-12 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 48: Figure 4-11. Full-Bridge Type I Circuit Diagram

    (+ε). • is the excitation voltage. • is the lead resistance. • is the measured voltage. © National Instruments Corporation 4-13 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 49: Full-Bridge Type Ii

    Figure 4-13 shows the full-bridge type II circuit wiring diagram. (+ ) (– (– ) Bending Axial Figure 4-12. Full-Bridge Type II Rejecting Axial and Measuring Bending Strain NI PXI-4220 User Manual 4-14 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 50 (+ε). • is the excitation voltage. • is the lead resistance. • is the measured voltage. © National Instruments Corporation 4-15 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 51: Full-Bridge Type Iii

    Figure 4-14 shows how to position strain-gauge resistors in an axial configuration. Figure 4-15 shows the full-bridge type III circuit wiring diagram. NI PXI-4220 User Manual 4-16 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 52: Figure 4-14. Full-Bridge Type Iii Measuring Axial And Rejecting Bending Strain

    Poisson effect (–νε). • is an active strain-gauge element measuring tensile strain (+ε). © National Instruments Corporation 4-17 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 53: Ni Pxi-4220 Theory Of Operation

    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. NI PXI-4220 Theory of Operation This section provides information about the circuit features of the module.

  • Page 54: Figure 4-16. Block Diagram Of The Ni Pxi-4220

    Chapter 4 Theory of Operation Figure 4-16. Block Diagram of the NI PXI-4220 © National Instruments Corporation 4-19 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 55 1 or 20 gain setting of the instrumentation amplifier, permit the NI PXI-4220 to have 49 gain settings between 1 and 1,000. By default the NI PXI-4220 T/H circuitry is enabled to allow SS/H, which allows you to acquire synchronized measurements from both channels.

  • Page 56: Bridge Configuration And Completion

    The quarter-bridge completion resistor is socketed for easy replacement. The quarter-bridge completion resistor for AI 0 is located on the NI PXI-4220 at reference designator R5, and the completion resistor for AI 1 is located at R2.

  • Page 57: Remote Sense

    DC offset in the excitation and compensates for changes in lead resistance caused by temperature variation in the lead wires. Note NI recommends connecting the remote sense pins directly to the sensor to obtain optimum excitation voltage regulation and measurement accuracy. NI PXI-4220 User Manual 4-22 ni.com...
  • Page 58 Theory of Operation The NI PXI-4220 excitation output circuits set the output voltage by monitoring the remote sense pins. Hence, the NI PXI-4220 corrects for a voltage (I × R) drop in the excitation leads between the module and the bridge, even if lead resistance changes with temperature.

  • Page 59: Gain/Input Range

    Theory of Operation Gain/Input Range In normal NI PXI-4220 operation you do not need to set the gain. NI-DAQmx automatically sets the appropriate gain based on the range of your task or global channel, or the input limits set in LabVIEW.

  • Page 60: Filter

    For example, because the NI PXI-4220 DAQ circuitry has a maximum analog input range of ±10 V and you have set the maximum input to the NI PXI-4220 to be +12 mV, set the gain to the setting closest to 10 V...

  • Page 61: Offset Null Compensation

    Theory of Operation 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.

  • Page 62: Shunt Calibration

    SCA (pin 4), QTR/SCB (pin 9), and SCCOM (pin 5) on the D-SUB connectors. Each shunt calibration circuit consists of a resistor in series with a switch. The NI PXI-4220 shunt calibration switch is a long-life solid-state switch. The electronic switch is galvanically isolated from ground;...

  • Page 63: Simultaneous Sample And Hold

    T/H circuitry. The outputs of the T/H amplifiers follow their inputs, also called tracking the inputs, until they receive a hold signal from the DAQ circuitry. Both channels on the NI PXI-4220 hold their signal at the same time. Multiple NI PXI-4220 devices can be synchronized, allowing you to simultaneously sample channels on multiple modules.

  • Page 64: Figure 4-17. Signal During Simultaneous Sample And Hold Sampling

    It is possible to enable and disable SS/H programmatically in NI-DAQmx, although NI recommends that you leave SS/H enabled for 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 ©...

  • Page 65: Maximum Acquisition Rate

    50 or 60 Hz powerline noise. The minimum NI PXI-4220 CMRR is 85 dB at gains ≥20. This results in 0.006% of the CMV introduced as error on the measured signal.

  • Page 66: Effective Cmr

    Timing and Control Functional Overview The NI PXI-4220 is similar to the NI E Series DAQ device architecture in many ways. This architecture uses the NI data acquisition system timing controller (DAQ-STC) for time-related functions. The DAQ-STC consists of two timing groups that control AI and general-purpose counter/timer functions.

  • Page 67: Programmable Function Inputs

    (SI2) counter TC. Programmable Function Inputs PFI0 is connected to the front SMB connector of the NI PXI-4220. Software can select PFI0 as the external source for a given timing signal. Any timing signal can use the PFI0 pin as an input, and multiple timing signals can simultaneously use the same PFI.

  • Page 68: Device And Pxi Clocks

    A/D conversions, digital-to-analog converter (DAC) updates, or general-purpose signals at the I/O connector. The NI PXI-4220 can use either its internal 20 MHz master timebase or an external timebase received over the PXI trigger bus on the PXI clock line.

  • Page 69: Figure 4-19. Ni Pxi-4220 Pxi Trigger Bus Signal Connection

    PXI Trigger<7> Switch Master Timebase Figure 4-19. NI PXI-4220 PXI Trigger Bus Signal Connection Table 4-4 provides more information about each of the timing signals available on the PXI trigger bus. For more detailed timing signal information, refer to Appendix B, Timing Signal Information.

  • Page 70: Table 4-4. Pxi Trigger Bus Timing Signals

    AI SAMPLE CLK Input This timebase provides the Input Input TIMEBASE master clock from which the sample clocks are derived. © National Instruments Corporation 4-35 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 71: Developing Your Application

    Developing Your Application in NI-DAQmx Note If you are not using an NI ADE, or if you are using an NI ADE prior to version 7.0 or an unlicensed copy of an NI ADE, additional dialog boxes from the NI License Manager appear allowing you to create a task or global channel using the DAQ Assistant in unlicensed mode.

  • Page 72: Figure 5-1. Typical Program Flowchart

    Calibration? Graphical Shunt Calibration Display Tools Operation Continue Sampling? Start Measurement Read Measurement Stop Measurement Clear Task Figure 5-1. Typical Program Flowchart NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 73: General Discussion Of Typical Flow Chart

    If you are using an ADE other than an NI ADE, or if you want to explicitly create and configure a task for a certain type of acquisition, you can programmatically create the task from your ADE using function or VI calls.

  • Page 74: Adjusting Timing And Triggering

    Configuring Channel Properties All of the different ADEs used to configure the NI PXI-4220 access an underlying set of NI-DAQmx properties. Table 5-1 lists of the properties that configure the NI PXI-4220. You can use this list to determine what kind of properties you need to set to configure the device for your application.
  • Page 75 Chapter 5 Developing Your Application Table 5-1. NI-DAQmx Properties (Continued) Property Short Name Description Analog Input» Enables the lowpass AI.Lowpass.Enable General Properties»Filter» filter of the channel. Analog Lowpass»Enable Analog Input» Specifies in hertz the AI.Lowpass.CutoffFreq General Properties»Filter» frequency corresponding Analog Lowpass»...

  • Page 76: Perform Offset Null Compensation

    Sample and Hold Enable device. This is not a complete list of NI-DAQmx properties and does not include every Note property you may need to configure your application. It is a representative sample of important properties to configure for strain and Wheatstone bridge measurements. For a complete list of NI-DAQmx properties and more information about NI-DAQmx properties, refer to your ADE Help.

  • Page 77: Perform Shunt Calibration

    Some custom scaling applications require the actual excitation voltage applied to the bridge instead of the nominal excitation voltage output by the NI PXI-4220. You can scan the remote sense pins RSX+ (pin 3) and RSX– (pin 8) with the DAQmx physical channels Dev X /_pPos X to find the actual excitation voltage.

  • Page 78: Completing The Application

    NI ADEs provide easy to use tools for graphical display, such as charts, graphs, slide controls, and gauge indicators. NI ADEs have tools that allow you to easily save the data to files such as spreadsheets for easy viewing, ASCII files for universality, or binary files for smaller file sizes.
  • Page 79 Perform Offset Null Use the DAQmx Perform Bridge Offset Nulling Calibration VI Compensation found at Functions»All Functions»NI Measurements» DAQmx - Data Acquisition»DAQmx Advanced»DAQmx Calibration. You can also perform offset null compensation when you create and configure your channels using the DAQ Assistant.

  • Page 80: Using A Daqmx Channel Property Node In Labview

    Clear Task DAQmx Clear Task.vi Using a DAQmx Channel Property Node in LabVIEW With the NI PXI-4220 you must use property nodes to disable SS/H. Note You can use property nodes in LabVIEW to manually configure your channels. To create a LabVIEW property node, complete the following steps: Launch LabVIEW.

  • Page 81: Figure 5-2. Labview Channel Property Node With Filtering Enabled At

    Refer to the LabVIEW Help for information about property nodes and specific Note NI-DAQmx properties. © National Instruments Corporation 5-11 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 82: Synchronization And Triggering

    The NI PXI-4220 that generates the start trigger and the timebase for all of the synchronized devices is called the master. The master NI PXI-4220 exports the shared timing signals through the PXI bus to the slave devices.

  • Page 83: Figure 5-3. General Synchronizing Flowchart

    Configure Slave Channel Continue Sampling? More Slave Tasks? Clear Master Task, Clear Slave Task Figure 5-3. General Synchronizing Flowchart © National Instruments Corporation 5-13 NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

  • Page 84: Synchronizing The Ni Pxi-4220 Using Labview

    This section describes in more detail the steps shown in the general synchronizing flowchart in Figure 5-3. For more information about synchronizing the NI PXI-4220 using LabVIEW or for further instructions, select Help»VI, Function, & How-To Help from the LabVIEW menu bar.

  • Page 85: Other Application Documentation And Material

    • LabVIEW Example Programs, available by selecting Open» Examples from the opening screen. Most of the examples applicable to the NI PXI-4220 are located in Hardware Input and Output» DAQmx»Analog Measurements and Hardware Input and Output»DAQmx»Synchronization»Multi-Device. Note The example program , located Acq Strain Samples (with Calibration).vi...

  • Page 86: Calibrating The Ni Pxi-4220

    System calibration removes the offset and gain errors, two sources of potential measurement errors. Calibrating the NI PXI-4220 The NI PXI-4220 is shipped with a calibration certificate and is calibrated at the factory to the specifications described in Appendix A, Specifications. Calibration constants are stored on the NI PXI-4220.

  • Page 87: External Device Calibration

    Note To maintain the accuracy specifications in Appendix A, Specifications, NI recommends performing an internal calibration at an ambient temperature within ±1 °C of the acquisition temperature. External Device Calibration NI recommends you perform an external calibration once a year. At the time of publication, there is currently no external calibration procedure document available for the NI PXI-4220.

  • Page 88: Appendix A Specifications

    Specifications This appendix lists the specifications for the NI PXI-4220 device. These specifications are typical at 25 °C unless otherwise noted. All specifications are with SS/H enabled unless otherwise noted. Analog Input Number of input channels ...... 2 Voltage gain settings......X1 to X1000 with the following gain settings: 1;...
  • Page 89 Appendix A Specifications NI PXI-4220 Accuracy Information Absolute Accuracy Noise + Quantization Temperature Drift µ Offset Absolute Nominal % of Reading Maximum Single Gain Drift Drift Accuracy at µ µ Range Gain 1 Year Offset ( Averaged (%/°C) /°C) Full Scale ±10.0 V...
  • Page 90 Pre-calibration errors Pre-calibration gain error ....±18,900 ppm max Signal conditioning component only....... ±1% max The pre-calibration errors apply only for users doing register-level programming. NI-DAQmx users do not see the pre-calibration errors. © National Instruments Corporation NI PXI-4220 User Manual...
  • Page 91 NMR, 10 Hz filter.........–62 dB at 60Hz typ Stability Recommended warm-up time....15 min Gain drift (with self-calibration at temperature) ..±40 ppm/°C max Gain drift (without self-calibration) ..±45 ppm/°C max NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 92 Without remote sense...... ±0.30% Temperature drift ........±0.005%/°C, ±30 µV/°C max Noise, DC to 10 kHz ......200 µV © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 93 Half-bridge completion is performed inside the module and configured under software control. The quarter-bridge completion resistor is located near the front of the PXI-4220 and is socketed. Resistors shipped with the PXI-4220 are 350 Ω (installed) and 120 Ω (in bag with kit) RN-55 style (standard 1/4 W size). The tolerance is ±0.1% and the temperature coefficient is 10 ppm/°C max.
  • Page 94 ±10 V of each other. Maximum working voltage refers to the signal voltage plus the common mode voltage. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 95 Humidity ..........10 to 90% RH, noncondensing Maximum altitude........2,000 m Pollution Degree (indoor use only)........2 Safety The PXI-4220 is designed to meet the requirements of the following standards of safety for electrical equipment for measurement, control, and laboratory use: • IEC 61010-1, EN 61010-1 •...
  • Page 96 Appendix A Specifications CE Compliance The PXI-4220 meets the essential requirements of applicable European Directives, as amended for CE marking, as follows: Low-Voltage Directive (safety) ..... 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.
  • Page 97 Connecting Timing Signals Caution Exceeding the maximum input voltage ratings listed in Appendix A, Specifications, can damage the device and the computer. NI is not liable for any damage resulting from such signal connections. Programmable Function Input Connections You can externally control seven internal timing signals from PFI0 and the PXI trigger bus pins.
  • Page 98 AI START TRIG AI REF TRIG AI SAMP CLK AI CONV CLK Scan Counter Figure B-2. Typical Pretriggered Sequence NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 99 Figure B-3. AI START TRIG Input Signal Timing = 50 to 100 ns Figure B-4. AI START TRIG Output Signal Timing © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 100 Figures B-5 and B-6 show the input and output timing requirements for AI REF TRIG. Rising-Edge Polarity Falling-Edge Polarity = 10 ns minimum Figure B-5. AI REF TRIG Input Signal Timing NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 101 This output is set to high-impedance at startup. Figures B-7 and B-8 show the input and output timing requirements for AI SAMP CLK. © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 102 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 period. NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 103 AI CONV CLK. Rising-Edge Polarity Falling-Edge Polarity = 10 ns minimum Figure B-9. AI CONV CLK Input Signal Timing © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 104 Separate the AI CONV CLK pulses by at least one conversion period. The NI PXI-4220 sample interval counter generates AI CONV CLK unless you select an external source. The AI SAMP CLK signal starts the counter, which counts down and reloads itself until the scan finishes.
  • Page 105 AI SAMPLE CLK TIMEBASE. = 50 ns minimum = 23 ns minimum Figure B-11. AI SAMPLE CLK TIMEBASE Signal Timing © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 106 Figure B-12 shows the timing for AI HOLD COMPLETE. The polarity of AI HOLD COMPLETE is not software selectable when Note programmed using NI-DAQmx. It is a positive polarity pulse. AI CONV CLK AI HOLD COMPLETE = 50 to 100 ns = 400 to 500 ns Figure B-12.
  • Page 107 Slide the device completely out. The next time you restart the computer the NI PXI-4220 will have a red circle with a white X inside it next to the device in MAX.
  • Page 108 MAX: Expand Devices and Interfaces to display the list 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.
  • Page 109 This appendix lists common questions related to the use of the NI PXI-4220. Which version of NI-DAQ works with the NI PXI-4220 and how do I get the most current version of NI-DAQ? You must have NI-DAQ 7.0 or later and use NI-DAQmx. Visit ni.com...
  • Page 110 NI PXI-4220. If I am powering my bridge-based transducers with an external voltage source, what 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 NI PXI-4220.
  • Page 111 © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 112 Celsius CalDAC calibration DAC NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 113 DAQ operation DAQ-STC data acquisition system timing controller chip © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 114 NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 115 © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 116 R = KS, where R = response, S = stimulus, and K = a constant least significant bit Measurement & Automation Explorer—NI software for configuring devices and channels. maximum working the highest voltage with respect to ground that should be applied to an input...
  • Page 117 National Instruments NI-DAQ NI driver software for DAQ hardware NI-DAQmx the latest NI-DAQ driver with new VIs, functions, and development tools for controlling measurement devices noise an undesirable electrical signal—noise comes from external sources such as the AC power line, motors, generators, transformers, fluorescent lights,...
  • Page 118 NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 119 Glossary See referenced single-ended configuration. RTSI bus real-time system integration bus—the NI timing bus that connects DAQ devices directly, for precise synchronization of functions seconds samples samples per second—used to express the rate at which a DAQ device samples an analog signal...
  • Page 120 WFTRIG waveform generation trigger signal NI PXI-4220 User Manual G-10 ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 121 DAQ timing connections, B-2 excitation level, 3-2 filter bandwidth, 3-3 gain, 3-3, 4-24 null potentiometers, 3-3 conventions used in the manual, iv © National Instruments Corporation NI PXI-4220 User Manual Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...
  • Page 122 Index filters Measurement & Automation Explorer (MAX) bandwidth configuration, 3-3 removing NI PXI-4220, C-2 questions about, D-1 measurements full-bridge configuration I, 2-9, 4-12 calibrating PXI-4220, 5-16 full-bridge configuration II, 2-10, 4-14 strain gauge connections full-bridge configuration III, 2-11, 4-16 full-bridge configuration I, 2-9, 4-12...
  • Page 123 Index operation of PXI-4220. See theory of regulatory compliance specifications, A-9 operation remote sense, 2-12 removing NI PXI-4220 from Measurement & Automation Explorer (MAX), C-2 PFIs (programmable function inputs) from PXI chassis, C-1 timing connections, B-1 RTSI clocks, 4-33 posttriggered data acquisition...
  • Page 124 4-19 TRIG2 signal, B-4 excitation, 4-21 See also PFI1/TRIG2 signal null compensation, 4-26 troubleshooting, questions and answers, D-1 shunt calibration, 4-27 NI PXI-4220 User Manual ni.com Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com...

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