National Instruments SC Express NI PXIe-4339 User Manual
8 ch, 24-bit, 25.6 ks/s universal bridge input module
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- User manual and specifications (36 pages) ,
- Calibration procedure (30 pages) ,
- Installation manual (20 pages)
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Summary of Contents for National Instruments SC Express NI PXIe-4339
- Page 1 SC Express NI PXIe-4339 User Manual 8 Ch, 24-bit, 25.6 kS/s Universal Bridge Input Module NI PXIe-4339 User Manual August 2015 376020C-01...
- Page 2 Tel: 866 ASK MYNI (275 6964) For further support information, refer to the NI Services appendix. To comment on National Instruments documentation, refer to the National Instruments website at ni.com/info and enter the Info Code feedback. © 2014–2015 National Instruments. All rights reserved.
- Page 3 National Instruments Corporation. National Instruments respects the intellectual property of others, and we ask our users to do the same. NI software is protected by copyright and other intellectual property laws. Where NI software may be used to reproduce software or other materials belonging to others, you may use NI software only to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction.
- Page 4 ™ The ExpressCard word mark and logos are owned by PCMCIA and any use of such marks by National Instruments is under license. The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft Corporation in the United States and other countries.
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Page 5: Table Of Contents
Alias-Free Bandwidth..................2-26 Filter Group Delay.................... 2-26 Supported Data Rates ....................2-27 Hardware-Timed Single Point Acquisitions............. 2-27 Hardware-Timed Single Point Acquisition Model........... 2-28 Maximum HWTSP Rate Analysis................2-28 2 kHz Control Loop Rate Calculation Example..........2-29 © National Instruments | v... - Page 6 Contents Timing and Triggering....................2-30 Sample Clock Timebase ................... 2-30 External Clock ....................2-30 Digital Triggering ..................... 2-30 Analog Triggering..................... 2-31 Triggering and Filter Delay ................2-33 Synchronization ......................2-34 Reference Clock Synchronization ..............2-34 TEDS ........................2-35 Configuring and Using TEDS in Software ............2-36 Accessory Auto-Detection ..................
- Page 7 Window Triggering ................2-33 Tables Table 2-1. Front Connector Signal Pin Assignments ..........2-21 Table 2-2. I/O Connector Signal Descriptions............2-22 Table 2-3. Wide Bandwidth Analog Output Nominal Gain ........2-24 Table 3-1. PXIe_DSTAR Line Descriptions ............3-2 © National Instruments | vii...
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Page 8: Getting Started
Specifications for step-by-step software and hardware installation instructions. Module Specifications Refer to the NI PXIe-4339 Specifications document for module specifications. Module Accessories Refer to for information about and a complete listing of supported ni.com/scexpress accessories. © National Instruments | 1-1... -
Page 9: Using The Module
The output of a Wheatstone bridge is measured between the middle nodes of the two voltage dividers. A physical phenomena, such as a change in strain or temperature applied © National Instruments | 2-1... -
Page 10: Connection Options To Correct For Resistance Errors
Chapter 2 Using the Module to a specimen, changes the resistance of the sensing elements in the Wheatstone bridge, resulting in a bridge output voltage that is proportional to the physical phenomena. The output voltage of the bridge scales with the excitation voltage. However, the ratio of the bridge output (V ) and the excitation voltage (V ) remains fixed over variations in excitation voltage, and it is this... -
Page 11: Shunt Calibration
This change is then measured and compared to the expected bridge output. The result can be used to correct gain errors in the entire measurement path or to simply verify general operation in the setup. © National Instruments | 2-3... -
Page 12: Strain Gage Sensor Configurations
Chapter 2 Using the Module Strain Gage Sensor Configurations This section describes the configurations and signal connection of various supported strain-gage configuration types. Quarter-Bridge Type I This section provides information for the quarter-bridge strain-gage configuration type I. The quarter-bridge type I measures either axial or bending strain. Figure 2-3 shows how to position a strain-gage resistor in an axial and bending configuration. -
Page 13: Figure 2-4. Quarter-Bridge I Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-5... -
Page 14: Quarter-Bridge Type Ii
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain ------------------------------- - GF 1 To compensate for lead resistance errors, use shunt calibration. Quarter-Bridge Type II This section provides information for the quarter-bridge strain-gage configuration type II. The quarter-bridge type II configuration measures either axial or bending strain. -
Page 15: Figure 2-6. Quarter-Bridge Ii Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-7... -
Page 16: Half-Bridge Type I
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain ------------------------------- - GF 1 Half-Bridge Type I This section provides information for the half-bridge strain-gage configuration type I. The half-bridge type I measures either axial or bending strain. -
Page 17: Figure 2-8. Half-Bridge Type I Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: (strained) V (unstrained) – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-9... -
Page 18: Half-Bridge Type Ii
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain -------------------------------------------------------------- - 2V 1 GF 1 – – Half-Bridge Type II This section provides information for the half-bridge strain-gage configuration type II. The half-bridge type II only measures bending strain. -
Page 19: Figure 2-10. Half-Bridge Type Ii Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-11... -
Page 20: Full-Bridge Type I
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain ( ----------- - Full-Bridge Type I This section provides information for the full-bridge strain-gage configuration type I. The full-bridge type I only measures bending strain. Figure 2-11 shows how to position strain-gage resistors in a bending configuration. -
Page 21: Figure 2-12. Full-Bridge Type I Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-13... -
Page 22: Full-Bridge Type Ii
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain ( -------- Full-Bridge Type II This section provides information for the full-bridge type II strain-gage configuration. The full-bridge type II only measures bending strain. Figure 2-13 shows how to position strain-gage resistors in a bending configuration. -
Page 23: Figure 2-14. Full-Bridge Type Ii Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-15... -
Page 24: Full-Bridge Type Iii
Chapter 2 Using the Module To convert module readings to strain use the following equation: – strain ------------------------- - GF 1 Full-Bridge Type III This section provides information for the full-bridge strain-gage configuration type III. The full-bridge type III only measures axial strain. -
Page 25: Figure 2-16. Full-Bridge Type Iii Circuit Diagram
—Offset compensated ratiometric bridge output defined by the following equation: V strained unstrained – ---------------------------------------------------------------------------------- - The ratio of the bridge output voltage and the excitation voltage is done Note internally on the NI PXIe-4339. © National Instruments | 2-17... -
Page 26: Force, Pressure, And Torque Sensor Configurations
Chapter 2 Using the Module To convert module readings to strain use the following equation: 2 – V strain ----------------------------------------------------------- - GF V 1 – – Force, Pressure, and Torque Sensor Configurations The NI PXIe-4339 can be used with force sensors (such as load cells), pressure sensors, or torque sensors that have the following characteristics: •... - Page 27 The two-point linear conversion uses the following equations: physical physical – -------------------------------------------------------------- electrical electrical – b = physical - m × electrical physical reading = m × V © National Instruments | 2-19...
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Page 28: Shielding And Grounding Considerations
Chapter 2 Using the Module If offset nulling (bridge balancing) is used to compensate for offset, then the zero point of the sensor can be assumed to output exactly 0 V/V, simplifying these equations: physical --------------------------- - electrical physical reading = m × V When the calibration certificate of the sensor provides a table of more than two calibration points or a polynomial expression, table or polynomial scaling can produce more accurate results by compensating for non-linearity in the response of the sensor. -
Page 29: Table 2-1. Front Connector Signal Pin Assignments
Column B Column C Channel AIGND Column AIGND AIGND AIGND DGND Channel AOGND AO0+ AO1+ AO4+ AO2+ AO3+ AO5+ AO6+ AO7+ AIGND AIGND AIGND PFI0 RSVD DGND RSVD Channel RSVD is reserved RSVD RSVD RSVD © National Instruments | 2-21... -
Page 30: I/O Connector Signal Descriptions
Chapter 2 Using the Module I/O Connector Signal Descriptions Table 2-2 describes the signals found on the I/O connector. Table 2-2. I/O Connector Signal Descriptions Signal Names Direction Description AIGND — Analog Input Ground AOGND — Analog Output Ground AI<0..7>+, AI<0..7>- Input Analog Input Channels 0 to 7—AI+ and AI- are the positive and negative inputs of the... -
Page 31: Ni Pxie-4339 Block Diagram
ADC input. The ADC then performs a ratiometric measurement of the input signal versus the reference signal to determine the actual deflection of the bridge or sensor. In voltage mode, the ADC voltage reference is fed by a stable 2.5 V voltage source. © National Instruments | 2-23... -
Page 32: Wide Bandwidth Analog Output
Chapter 2 Using the Module The NI PXIe-4339 supports half-, quarter-, and full-bridge measurements. Half-bridge completion and shunt calibration switches are provided on the NI PXIe-4339. Quarter-bridge completion and shunt calibration resistors are provided on the TB-4339/B/C terminal blocks. AO+ is a single-ended, current-limited, external-voltage-fault protected copy of the front end gain stage. -
Page 33: Nyquist Frequency And Nyquist Bandwidth
Lowpass filtering to eliminate components above the Nyquist frequency either before or during the digitization process can guarantee that the digitized data set is free of aliased components. The NI PXIe-4339 modules employ both digital and analog lowpass filters to achieve this protection. © National Instruments | 2-25... -
Page 34: Passband
Chapter 2 Using the Module The NI PXIe-4339 modules include an oversampled architecture and sharp digital filters with cut-off frequencies that track the sampling rate. Thus, the filter automatically adjusts to follow the Nyquist frequency. Although the digital filter eliminates almost all out-of-band components, it is still susceptible to aliases from certain narrow frequency bands located at frequencies far above the sampling rate. -
Page 35: Supported Data Rates
1.90976 ms 3.8043 ms ----------------------- - 25600 S/s If a 10 V range is used, total delay is 3.8043 ms + 6.1 μs = 3.8104 ms. Refer to the NI PXIe-4339 Specifications for more information. © National Instruments | 2-27... -
Page 36: Hardware-Timed Single Point Acquisition Model
Chapter 2 Using the Module Checking document for more information. To access this document, go to ni.com/info enter the Info Code daqhwtsp Hardware-Timed Single Point Acquisition Model The HWTSP data path is optimized for low-latency applications and is different than that which is used in buffered acquisition model (default). -
Page 37: Khz Control Loop Rate Calculation Example
Using Equation 2-1 and the Transfer Time from the sample system described in this section, you can determine that an application time of 480 μs is required to close a 2 kHz control loop. Application Time ≤ 500 µs - Transfer Time © National Instruments | 2-29... -
Page 38: Timing And Triggering
Chapter 2 Using the Module Application Time ≤ 500 µs - 20 µs Application Time ≤ 480 µs Any application taking more than 480 μs will fail to close the 2 kHz control loop. When analyzing the bandwidth of the system, you must consider the group delay of all the components of the system. -
Page 39: Analog Triggering
This jitter usually has no effect on data processing, and you can decrease this jitter by sampling at a higher rate. You can use several analog triggering modes with the NI PXIe-4339 modules, for instance analog edge, analog edge with hysteresis, and window triggering. © National Instruments | 2-31... -
Page 40: Figure 2-23. Analog Level Trigger On Rising Slope
Chapter 2 Using the Module Analog Edge Triggering For analog edge triggering, configure the module to detect a certain signal level and slope, either rising or falling. Figure 2-23 shows an example of rising edge analog triggering. The analog comparison becomes true when the signal starts below Level and then crosses above Level. Figure 2-23. -
Page 41: Triggering And Filter Delay
In all cases, the NI PXIe-4339 interprets triggers based on where they occur in time. The hardware automatically compensates for its group delay such that data from this module will line up closely in time with the occurrence of the trigger event. However, the group delay affects how © National Instruments | 2-33... -
Page 42: Synchronization
Chapter 2 Using the Module long it takes to receive data when starting an acquisition. Since linear phase FIR filters are used in the digital filtering, it is necessary to wait for the filter group delay to elapse after sending a sync pulse before the start trigger can be correctly handled in time. -
Page 43: Teds
This information is accessible in Measurement & Automation Explorer (MAX), VIs in LabVIEW, or by calling the equivalent function calls in a text-based ADE. For more information about TEDS plug and play sensors, refer to ni.com/pnp © National Instruments | 2-35... -
Page 44: Configuring And Using Teds In Software
Chapter 2 Using the Module Configuring and Using TEDS in Software To manually configure TEDS in MAX, right-click the NI PXIe-4339 module within the Configuration tree. Then select Configure TEDS from the pop-up menu. To programmatically configure TEDS, call the DAQmx Configure TEDS VI. Accessory Auto-Detection SC Express modules automatically detect compatible accessories or terminal blocks. -
Page 45: Sc Express Considerations
Triggers may be passed from one module to another, allowing precisely timed responses to asynchronous external events that are being monitored or controlled. Triggers can be used to synchronize the operation of several different PXI peripheral modules. © National Instruments | 3-1... -
Page 46: Pxi_Star Trigger
Chapter 3 SC Express Considerations In a PXI chassis with more than eight slots, the PXI trigger lines may be divided into multiple independent buses. Refer to the documentation for your chassis for details. PXI_STAR Trigger In a PXI Express system, the Star Trigger bus implements a dedicated trigger line between the system timing slot and the other peripheral slots. -
Page 47: Offset Nulling (Bridge Balancing)
The NI PXIe-4339 does not have any internal hardware nulling circuitry, however, its input range is sufficiently wide so that the inputs will not saturate even with a relatively large initial bridge offset. © National Instruments | A-1... -
Page 48: Ni Services
NI Services National Instruments provides global services and support as part of our commitment to your success. Take advantage of product services in addition to training and certification programs that meet your needs during each phase of the application life cycle; from planning and development through deployment and ongoing maintenance. - Page 49 Appendix B NI Services • Training and Certification—The NI training and certification program is the most effective way to increase application development proficiency and productivity. Visit for more information. ni.com/training – The Skills Guide assists you in identifying the proficiency requirements of your current application and gives you options for obtaining those skills consistent with your time and budget constraints and personal learning preferences.
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