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National Instruments SCXI-1520 User Manual

National Instruments SCXI-1520 User Manual

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SCXI-1520 User Manual
SCXI-1520 User Manual
May 2009
372583E-01

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Summary of Contents for National Instruments SCXI-1520

  • Page 1 SCXI SCXI-1520 User Manual SCXI-1520 User Manual May 2009 372583E-01...
  • Page 2 Thailand 662 278 6777, Turkey 90 212 279 3031, United Kingdom 44 (0) 1635 523545 For further support information, refer to the Technical Support Information Document. To comment on National Instruments documentation, refer to the National Instruments Web site at and enter the info code ni.com/info...

  • Page 3: Important Information

    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 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, AO <3..0>. » The » symbol leads you through nested menu items and dialog box options to a final action.

  • Page 5: Table Of Contents

    Installing Application Software, NI-DAQ, and the E/M Series DAQ Device ....1-5 Installing the SCXI-1520 Module into the SCXI Chassis.......1-5 Connecting the SCXI-1520 in an SCXI Chassis to an E/M Series DAQ Device for Multiplexed Scanning ............1-5 Connecting the SCXI-1520 in a PXI/SCXI Combination Chassis to an E/M Series DAQ Device for Multiplexed Scanning ........1-5...
  • Page 6 Contents Chapter 3 Configuring and Testing SCXI-1520 Software-Configurable Settings..............3-1 Common Software-Configurable Settings ............3-1 Bridge Configuration ................ 3-1 Excitation Level................3-2 Filter Bandwidth ................3-2 Gain/Input Range................3-3 Null Potentiometers ................3-4 Shunt Calibration Switches .............. 3-4 Modes of Operation ................3-5 Simultaneous Sample and Hold............
  • Page 7 Measurement Studio (Visual Basic, .NET, and C#)........5-14 Programmable NI-DAQmx Properties..........5-16 Developing Your Application in Traditional NI-DAQ (Legacy) ........5-18 Traditional NI-DAQ (Legacy) in LabVIEW...........5-19 Typical Program Flow ..............5-20 Configuring the SCXI-1520 Settings Using Traditional NI-DAQ (Legacy) in LabVIEW ..................5-22 © National Instruments Corporation SCXI-1520 User Manual...
  • Page 8 Traditional NI-DAQ (Legacy) CVI Examples..........5-36 Traditional NI-DAQ (Legacy) Measurement Studio Examples ..... 5-36 Calibrating the Strain System..................5-37 Calibrating the SCXI-1520 ................5-37 Internal Calibration Procedure............5-37 Internal Calibration Using LabVIEW..........5-37 Internal Calibration Using a C-Based ADE ........5-38 External Calibration................
  • Page 9 Figure 4-14. Full-Bridge Type III Measuring Axial and Rejecting Bending Strain...............4-17 Figure 4-15. Full-Bridge Type III Circuit Diagram ...........4-17 Figure 4-16. Block Diagram of SCXI-1314/SCXI-1520 Combination .....4-19 Figure 4-17. Signal During Simultaneous Sample-and-Hold Sampling....4-29 Figure 5-1. Typical Program Flowchart..............5-3 Figure 5-2.
  • Page 10 Contents Figure 5-4. Using the AI Parameter VI to Set Up the SCXI-1520 ......5-24 Figure 5-5. Offset Null and Shunt Calibration Flowchart ........5-30 Figure C-1. Removing the SCXI-1520..............C-2 Tables Table 1-1. Accessories Available for the SCXI-1520 ..........1-2 Table 2-1.

  • Page 11: About The Scxi-1520

    You can configure all settings on a per channel basis in software. The SCXI-1520 is configured using Measurement & Automation Explorer (MAX) or through NI-DAQmx property nodes. With the SCXI-1520 and the accessory SCXI-1314 terminal block, you can do the following: •...

  • Page 12: Table 1-1. Accessories Available For The Scxi-1520

    Table 1-1. Accessories Available for the SCXI-1520 Accessory Description † SCXI-1314 Screw terminal block—Mounts on the front of the SCXI-1520 module. It includes connections and sockets for two shunt calibration resistors and a quarter-bridge completion resistor per channel. †† SCXI-1314T RJ-50 terminal block—Mounts on the front of the SCXI-1520 module.

  • Page 13: National Instruments Documentation

    There are no quarter-bridge completion resistors in the SCXI-1310 or TBX-96. If you are connecting a quarter-bridge sensor to an SCXI-1520 using an SCXI-1310 or TBX-96, you must place an external resistor between the pins that correspond to PX– and SX+ on the terminals. Refer to Chapter 2, Connecting Signals, for more information.
  • Page 14 DAQ device, and application hints. • Software documentation—You may have both application software and NI-DAQ software documentation. National Instruments (NI) application software includes LabVIEW, LabWindows/CVI, and Measurement Studio. After you set up the hardware system, use either your application software documentation or the NI-DAQ documentation to help you write your application.

  • Page 15: Installing Application Software, Ni-Daq, And The E/M Series Daq Device

    Refer to the DAQ Getting Started Guide packaged with the NI-DAQ software to install your application software, NI-DAQ driver software, and the DAQ device to which you will connect the SCXI-1520. NI-DAQ 7.0 or later is required to configure and program the SCXI-1520 module. If you do not have NI-DAQ 7.0 or later, you can either contact a NI sales...

  • Page 16: Verifying The Scxi-1520 Installation In Software

    Chapter 1 About the SCXI-1520 Verifying the SCXI-1520 Installation in Software Refer to the SCXI Quick Start Guide for information on verifying the SCXI installation. Installing SCXI Using NI-DAQmx in Software Refer to the SCXI Quick Start Guide for information on installing modules using NI-DAQmx in software.

  • Page 17: Troubleshooting The Self-Test Verification

    Chapter 1 About the SCXI-1520 After verifying and self-testing the installation, the SCXI system should operate properly with your ADE software. If the test did not complete successfully, refer to Chapter 3, Configuring and Testing, for troubleshooting steps. Troubleshooting the Self-Test Verification If the Self-Test Verification did not verify the chassis configuration, complete the steps in this section to troubleshoot the SCXI configuration.

  • Page 18: Troubleshooting In Traditional Ni-Daq (Legacy)

    Chapter 1 About the SCXI-1520 If the cabled module is not listed in the correct slot, complete the following troubleshooting steps: If the cabled module is not listed in the correct slot and the slot is empty, click the drop-down listbox next to the correct slot and select the cabled module.
  • Page 19 If the module is installed in the correct slot, power off the chassis, remove the module as specified in Appendix C, Removing SCXI-1520, and verify that no connector pins are bent on the rear signal connector. Reinstall the module as described in the Installing the...

  • Page 20: Connecting Signals

    Connecting Signals This chapter describes how to connect Wheatstone bridge sensors to the SCXI-1520 in quarter-, half-, and full-bridge configurations and for remote sensing. It also provides the front and rear signal pin assignments of the module. Connecting Bridge Sensor Signals...

  • Page 21: Quarter-Bridge Type Ii

    Chapter 2 Connecting Signals SCXI-1520 Set Bridge Configuration to Transducer SCXI-1314 Quarter Bridge – (gauge) – You must connect Shunt the shunt calibration Cal A wires externally using the terminal block screw connections. Figure 2-1. Quarter-Bridge I Circuit Diagram The following symbols apply to the circuit diagram and equations: •...

  • Page 22: Figure 2-2. Quarter-Bridge Ii Circuit Diagram

    Typically it is either physically close to the specimen or mounted on the same type material at the same temperature, but is not under strain. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Quarter Bridge –...

  • Page 23: Half-Bridge Type I

    Half-Bridge Type I This section provides information for connecting the half-bridge strain-gauge configuration type I. Figure 2-3 shows the half-bridge type I circuit wiring diagram. Note S– is left unwired. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Half Bridge – (gauge) –...

  • Page 24: Half-Bridge Type Ii

    Half-Bridge Type II This section provides information for connecting the half-bridge strain-gauge configuration type II. Figure 2-4 shows the half-bridge type II circuit wiring diagram. Note S– is left unwired. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Half Bridge – (gauge) –...

  • Page 25: Full-Bridge Type I

    Chapter 2 Connecting Signals Full-Bridge Type I This section provides information for connecting the full-bridge strain-gauge configuration type I. Figure 2-5 shows the full-bridge type I circuit wiring diagram. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Full Bridge – –...

  • Page 26: Full-Bridge Type Ii

    Chapter 2 Connecting Signals Full-Bridge Type II This section provides information for connecting the full-bridge strain-gauge configuration type II. Figure 2-6 shows the full-bridge type II circuit wiring diagram. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Full Bridge – –v –...

  • Page 27: Full-Bridge Type Iii

    This section provides information for connecting the full-bridge strain-gauge configuration type I. The full-bridge type III only measures axial strain. Figure 2-7 shows the full-bridge type III circuit wiring diagram. SCXI-1520 Set Bridge Transducer SCXI-1314 Configuration to Full Bridge –...

  • Page 28: Remote Sense

    NI recommends using remote sense if your application requires the improved accuracy. Refer to Chapter 4, Theory of Operation, for more information about using remote sense. Wire the SCXI-1520 for remote sense as shown in Figure 2-8. Transducer SCXI-1314 SCXI-1520 Run Separate Wires...

  • Page 29: Pin Assignments

    Chapter 2 Connecting Signals Pin Assignments The pin assignments for the SCXI-1520 front signal connector are shown in Table 2-1. The front signal connector is a special 96-pin DIN C male connector through which you make all signal connections. The terminal assignments are as follows: •...

  • Page 30: Table 2-1. Front Signal Pin Assignments

    SCA4 SCA4 RSVD S5– RSVD RS5– RS5+ RSVD P5– RSVD SCA5 SCA5 SCB6 S6– SCB6 RS6– RS6+ SCB7 P6– SCB7 SCA6 SCA6 RSVD S7– RSVD RS7– RS7+ RSVD P7– RSVD SCA7 SCA7 © National Instruments Corporation 2-11 SCXI-1520 User Manual...
  • Page 31 E/M Series DAQ device. The rear signal connector is shown in Table 2-2. The rear signal connector allows the DAQ device to access all eight differential analog output signals from the SCXI-1520. The positive terminal of each analog output is named CHX+ and the negative terminal CHX–.

  • Page 32: Table 2-2. Rear Signal Pin Assignments

    In parallel output mode, channel 0 is selected at the output multiplexer and is connected to CH 0. The seven other channels are directly connected to CH 1 through CH 7, respectively, on the rear connector. © National Instruments Corporation 2-13 SCXI-1520 User Manual...

  • Page 33: Table 2-3. Scxi-1520 Communication Signals

    DAQ device is cabled to the SCXI-1520. The communication signals between the DAQ device and the SCXI system are listed in Table 2-3. If the DAQ device is connected to the SCXI-1520, these digital lines are unavailable for general-purpose digital I/O.
  • Page 34 Chapter 2 Connecting Signals Table 2-3. SCXI-1520 Communication Signals (Continued) NI-DAQmx Traditional NI-DAQ SCXI Device Signal (Legacy) Device Signal Name Name Signal Name Direction Description SLOT0SEL* P0.2 DIO2 Input Slot 0 select—this signal taps into the SCXIbus INTR* line to...

  • Page 35: Configuring And Testing

    Configuring and Testing This chapter discusses configuring the SCXI-1520 in MAX for use with either NI-DAQmx or Traditional NI-DAQ (Legacy), creating and testing a virtual channel, global channel, and/or task. SCXI-1520 Software-Configurable Settings This section describes how to set the bridge configuration, voltage...

  • Page 36: Excitation Level

    Filter bandwidth is a software-configurable setting that allows you to select a lowpass filter cutoff frequency. You can choose 10 Hz, 100 Hz, 1 kHz, 10 kHz, or filter-bypass mode. If your application requires other cutoff frequencies, refer to Chapter 4, Theory of Operation. SCXI-1520 User Manual ni.com...

  • Page 37: Gain/Input Range

    Operation. Otherwise, you should determine the appropriate gain using the input signal voltage range and the full-scale limits of the SCXI-1520 output signal. For common strain-gauge configurations where the Gauge Factor is 2.0, the maximum input signal (in microvolts) is: ×...

  • Page 38: Null Potentiometers

    Configuring and Testing If you are using a DAQ device that has a maximum analog input range of ±10 V and you have a maximum input to the SCXI-1520 of +12 mV, set the gain to the setting closest to...

  • Page 39: Modes Of Operation

    Chapter 3 Configuring and Testing Modes of Operation The SCXI-1520 can operate in multiplexed mode or parallel mode. Using NI-DAQmx, you can operate the SCXI-1520 in either multiplexed or parallel mode. In Traditional NI-DAQ (Legacy), only multiplexed mode is supported. Refer to the...

  • Page 40: Ni-Daqmx

    Strain and custom voltage with excitation are the most commonly used NI-DAQmx Task or NI-DAQmx Global Channel types with the SCXI-1520. Use the Custom Voltage with Excitation NI-DAQmx task or global channel when measuring load, force, torque, pressure, or other bridge-based sensors: •...

  • Page 41: Creating A Strain Global Channel Or Task

    • Modes of operation—configure only using chassis installation in software. Refer to Chapter 1, About the SCXI-1520, for more information on chassis installation. The default setting in NI-DAQmx is multiplexed. • Simultaneous sample-and-hold settings—configure only using your application.

  • Page 42: Creating A Custom Voltage With Excitation Global Channel Or Task

    <Ctrl> key while selecting channels. Enter the specific values for your application in the Settings tab. Context help information for each setting is provided on the right side of the screen. SCXI-1520 User Manual ni.com...

  • Page 43: Traditional Ni-Daq (Legacy)

    Gain/input signal range—configure gain using module properties. When you set the minimum and maximum range of the virtual channel, the driver selects the best gain. The default gain setting for Traditional NI-DAQ (Legacy) is 100. © National Instruments Corporation SCXI-1520 User Manual...

  • Page 44: Configuring Module Property Pages In Traditional Ni-Daq (Legacy)

    Traditional NI-DAQ (Legacy). Configuring Module Property Pages in Traditional NI-DAQ (Legacy) Right-click the SCXI-1520 module you want to configure and select Properties. Click General. If the module you are configuring is connected to an E Series DAQ device, select that device by using Connected to.

  • Page 45: Creating A Strain Virtual Channel

    Calibrating a Strain Virtual Channel To calibrate a strain virtual channel, complete the following steps: Right-click the virtual channel you want to calibrate and select Properties. Click Calibration. Select the Engineering Units from the drop-down menu. © National Instruments Corporation 3-11 SCXI-1520 User Manual...

  • Page 46: Verifying The Signal

    Traditional NI-DAQ (Legacy). Verifying the Signal in NI-DAQmx Using a Task or Global Channel You can verify the signals on the SCXI-1520 using NI-DAQmx by completing the following steps: Expand the list of tasks and virtual channels by clicking the + next to Data Neighborhood.

  • Page 47: Verifying The Signal In Traditional Ni-Daq (Legacy)

    Chapter 3 Configuring and Testing For more information on how to further configure the SCXI-1520, or how to use Note LabVIEW to configure the module and take measurements, refer to Chapter 4, Theory of Operation. Verifying the Signal in Traditional NI-DAQ (Legacy) This section discusses how to verify the signal in Traditional NI-DAQ (Legacy) using channel strings and virtual channels.

  • Page 48: Verifying The Signal Using Strain Virtual Channel

    Click the + next to NI-DAQmx Tasks to expand the list of tasks. Select the strain task you previously created. Click the Device tab. Select the Auto Zero Mode and Lowpass Filter Cutoff Frequency from the dropdown lists. Click the Calibration button and follow the onscreen instructions. SCXI-1520 User Manual 3-14 ni.com...

  • Page 49: Theory Of Operation

    R and R compose one voltage divider circuit, and R compose the second voltage divider circuit. The output of a Wheatstone bridge is measured between the middle nodes of the two voltage dividers. © National Instruments Corporation SCXI-1520 User Manual...

  • Page 50: Strain Gauges

    MAX or perform scaling in your software application. This document discusses all of the mechanical, electrical, and scaling considerations of each strain-gauge configuration type supported by NI. SCXI-1520 User Manual ni.com...

  • Page 51: Acronyms, Formulas, And Variable Definitions

    – (unstrained)   ------------------------------------------------------------------------------ -   © National Instruments Corporation SCXI-1520 User Manual...

  • Page 52: Software Scaling And Equations

    Figure 4-2 shows how to position a strain-gauge resistor in an axial and bending configurations. Figure 4-3 shows the quarter-bridge type I circuit wiring diagram. (+ ) (+ ) Axial Bending Figure 4-2. Quarter-Bridge Type I Measuring Axial and Bending Strain SCXI-1520 User Manual ni.com...

  • Page 53: Figure 4-3. Quarter-Bridge I Circuit Diagram

    4 – V   strain ε ( ) × ------------------------------- ------ -   GF 1 where is the nominal gauge resistance of the sensor. is the lead resistance. GF is the Gauge Factor. © National Instruments Corporation SCXI-1520 User Manual...

  • Page 54: Quarter-Bridge Type Ii

    II. The quarter-bridge type II measures either axial or bending strain. Figure 4-4 shows how to position a strain-gauge resistor in an axial and bending configurations. Figure 4-5 shows the quarter-bridge type II circuit wiring diagram. SCXI-1520 User Manual ni.com...

  • Page 55: Figure 4-4. Quarter-Bridge Type Ii Measuring Axial And Bending Strain

    Completion resistors provide half-bridge completion. • Compensates for temperature. Sensitivity at 1000 με is ∼ 0.5 mV • input. Note S– and QTR are left unwired. (+ ) – – Figure 4-5. Quarter-Bridge II Circuit Diagram © National Instruments Corporation SCXI-1520 User Manual...
  • Page 56 (∼ <10 ft), depending on the wire gauge. For example, 10 ft of 24-AWG copper wire has a lead resistance of 0.25 Ω. The nominal value of R is equal to R SCXI-1520 User Manual ni.com...

  • Page 57: Half-Bridge Type I

    Poisson’s ratio of the specimen material. Sensitivity at 1000 με is ∼ 0.65 mV • input. Note S– is left unwired. (+ ) – – (– Figure 4-7. Half-Bridge Type I Circuit Diagram © National Instruments Corporation SCXI-1520 User Manual...
  • Page 58 (∼ <10 ft), depending on the wire gauge. For example 10 ft of 24-AWG copper wire has a lead resistance of 0.25 Ω. The nominal values of R and R equal R SCXI-1520 User Manual 4-10 ni.com...

  • Page 59: Half-Bridge Type Ii

    • Compensates for temperature. Sensitivity at 1000 με is ∼ 1 mV • input. Note S– is left unwired. (+ ) – – (– ) Figure 4-9. Half-Bridge Type II Circuit Diagram © National Instruments Corporation 4-11 SCXI-1520 User Manual...
  • Page 60 (∼ <10 ft), depending on the wire gauge. For example 10 ft of 24-AWG copper wire has a lead resistance of 0.25 Ω. The nominal values of R and R equal R SCXI-1520 User Manual 4-12 ni.com...

  • Page 61: Full-Bridge Type I

    • Compensates for lead resistance. Sensitivity at 1000 με is ∼ 2.0 mV • input. (– ) (+ ) – – (+ ) (– ) Figure 4-11. Full-Bridge Type I Circuit Diagram © National Instruments Corporation 4-13 SCXI-1520 User Manual...

  • Page 62: Full-Bridge Type Ii

    This section provides information for the full-bridge type II strain-gauge configuration. The full-bridge type II only measures bending strain. Figure 4-12 shows how to position strain-gauge resistors in a bending configuration. Figure 4-13 shows the full-bridge type II circuit wiring diagram. SCXI-1520 User Manual 4-14 ni.com...

  • Page 63: Figure 4-12. Full-Bridge Type Ii Rejecting Axial And Measuring Bending Strain

    The following symbols apply to the circuit diagram and equations: • is an active strain-gauge element measuring compressive Poisson effect (–νε). • is an active strain-gauge element measuring tensile Poisson effect (+νε). © National Instruments Corporation 4-15 SCXI-1520 User Manual...

  • Page 64: Full-Bridge Type Iii

    This section provides information for the full-bridge strain-gauge configuration type III. The full-bridge type III only measures axial strain. 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. SCXI-1520 User Manual 4-16 ni.com...

  • Page 65: Figure 4-14. Full-Bridge Type Iii Measuring Axial And Rejecting Bending Strain

    Figure 4-15. Full-Bridge Type III Circuit Diagram The following symbols apply to the circuit diagram and equations: • is an active strain-gauge element measuring compressive Poisson effect (–νε). • is an active strain-gauge element measuring tensile strain (+ε). © National Instruments Corporation 4-17 SCXI-1520 User Manual...

  • Page 66: Scxi-1520 Theory Of Operation

    SCXI-1314 terminal block unless the strain-gauge cable length is very short. The nominal values of R , and R equal R SCXI-1520 Theory of Operation This section includes a brief overview and a detailed discussion of the circuit features of the module. Refer to Figure 4-16 while reading this section.

  • Page 67: Figure 4-16. Block Diagram Of Scxi-1314/Scxi-1520 Combination

    Chapter 4 Theory of Operation Rear Signal Connector SCXIbus Connector Figure 4-16. Block Diagram of SCXI-1314/SCXI-1520 Combination © National Instruments Corporation 4-19 SCXI-1520 User Manual...
  • Page 68 The variable gain stage allows you to set the gain at many discrete settings between 1 and 50. These settings, along with the 1 or 20 setting of the instrumentation amplifier, permit the SCXI-1520 to have 49 gain settings between 1 and 1000.

  • Page 69: Bridge Configuration And Completion

    Theory of Operation eight channels for routing. The signal is routed to the E/M Series DAQ device channel 0 if the SCXI-1520 is the cabled module and/or to the SCXI backplane through the SCXIbus connector. If configured for parallel mode operation, the signals are routed through the rear signal connector to the digitizing DAQ device.

  • Page 70: Excitation

    Using the SCXI-1520. Excitation The SCXI-1520 provides DC excitation voltage for a Wheatstone bridge sensor. For half- and full-bridge applications, the excitation voltage is available at terminal block connections PX+ and PX–. For quarter-bridge applications, PX– is not used; instead, wire to terminals PX+ and QTRX.

  • Page 71: Remote Sense

    SCXI-1520, and Appendix B, Using SCXI Channel Strings with Traditional NI-DAQ (Legacy) 7.0 Later, for more information. Wire the SCXI-1520 for remote sense as shown in Figure 2-8, Remote-Sense Circuit Diagram. There are no configuration settings you need to change in the software.

  • Page 72: Gain

    If overall module gain is less than 20, the first stage is set to 1 and the appropriate second stage gain is applied. In normal operation of the SCXI-1520, you need not set the gain since NI-DAQ sets the gain based on the range of your virtual channel, task, or global channel, or the input limits set in LabVIEW.

  • Page 73: Filter Bandwidth And Cutoff Frequency

    SCXI-1520. Filter Bandwidth and Cutoff Frequency The SCXI-1520 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, or filter-bypass mode.

  • Page 74: Table 4-2. Control Codes For Coarse And Fine Offset Null Potentiometers

    NI-DAQmx and Traditional NI-DAQ (Legacy), refer to the Developing Your Application in NI-DAQmx section or the Developing Your Application in Traditional NI-DAQ (Legacy) section, respectively, of Chapter 5, Using the SCXI-1520. SCXI-1520 User Manual 4-26 ni.com...

  • Page 75: Shunt Calibration

    Chapter 5, Using the SCXI-1520. The SCXI-1520 has two independent shunt calibration circuits available for each channel at terminal sets SCAX and SCBX on the terminal block. Each shunt calibration circuit consists of a resistor in series with a switch. The SCXI-1520 shunt calibration switch is a long-life solid-state switch.

  • Page 76: Simultaneous Sample And Hold

    MIO DAQ devices to return synchronized samples of all channels with negligible skew time between channels. SS/H signal conditioning is performed on the SCXI-1520 with track-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 device.

  • Page 77: Figure 4-17. Signal During Simultaneous Sample-And-Hold Sampling

    SS/H if your application does not require simultaneous sampling and requires higher acquisition rates than are possible with SS/H enabled. Refer to the Developing Your Application in NI-DAQmx section of Chapter 5, Using the SCXI-1520, for more information about © National Instruments Corporation 4-29 SCXI-1520 User Manual...

  • Page 78: Maximum Simultaneous Sample And Hold Sample Rate Using Ni-Daqmx

    SS/H using NI-DAQmx in your application. Maximum Simultaneous Sample and Hold Sample Rate Using NI-DAQmx When using NI-DAQmx you can use the SCXI-1520 in multiplexed or parallel mode. Multiplexed Mode Use the following formula to calculate the maximum SS/H sample rate in...

  • Page 79: Table 4-3. Ni-Daqmx Values Used To Determine Maximum Sample Rate In Multiplexed Mode

    MIO (also minimum interchannel delay) TT is track time—the minimum time between the last AD conversion of the current scan and engaging the hold signal of SS/H channels of next scan © National Instruments Corporation 4-31 SCXI-1520 User Manual...

  • Page 80: Maximum Simultaneous Sample And Hold Using Traditional Ni-Daq (Legacy)

    50 μs for TT. ‡ SCXI Maximum Simultaneous Sample and Hold Using Traditional NI-DAQ (Legacy) When using Traditional NI-DAQ (Legacy), you can only use the SCXI-1520 in multiplexed mode. To use parallel mode, you must use NI-DAQmx. SCXI-1520 User Manual 4-32 ni.com...

  • Page 81: Table 4-5. Traditional Ni-Daq (Legacy) Values Used To Determine Maximum Sample Rate In Multiplexed Mode

    NI 6070E 1250000 30961 NI 6070E 1250000 9243 NI 6023E 200000 18640 NI 6023E 200000 5166 NI 6052E 333333 11047 NI 6052E 333333 2932 NI 6032E 100000 8324 NI 6032E 100000 2176 © National Instruments Corporation 4-33 SCXI-1520 User Manual...

  • Page 82: Modes Of Operation

    DAQ device. There are several possible scenarios for routing signals from the multiplexed modules to the DAQ device. If the scanned SCXI-1520 module is not directly cabled to the DAQ device, the module sends its signals through the SCXIbus to the cabled module.

  • Page 83: Theory Of Parallel Mode Operation

    Parallel mode is ideal for high speed acquisitions. In parallel mode, the eight conditioned analog output signals at the rear signal connector of the SCXI-1520, shown in Figure 4-16, are connected directly to the eight analog input channels on the DAQ device. When the SCXI-1520 operates in parallel mode, the DAQ device performs multiplexed scans of the SCXI-1520 parallel outputs.
  • Page 84 DAQ device. The T/H circuit of each channel is in hold mode during this time. This appears as glitches on the parallel outputs as the SCXI-1520 is sampled by the digitizing DAQ device. Due to these signal events, NI recommends that you not scan the SCXI-1520...

  • Page 85: Using The Scxi-1520

    Caution Electrostatic discharges (ESD) of 4 kV or greater may cause the SCXI-1520 to stop responding, resulting in a lost or erroneous reading. As a result, a software reset may be required to enhance immunity by restoring functionality in such a condition. A software reset can be accomplished by calling the DAQmx Reset Device function.

  • Page 86: Typical Program Flowchart

    Chapter 5 Using the SCXI-1520 Typical Program Flowchart Figure 5-1 shows a typical program flowchart for creating a task to configure channels, take a measurement, analyze the data, present the data, stop the measurement, and clear the task. SCXI-1520 User Manual...

  • Page 87: Figure 5-1. Typical Program Flowchart

    Chapter 5 Using the SCXI-1520 Create Task Using DAQ Assistant? Create a Task Programmatically Create Task in DAQ Assistant or MAX Create Strain or Custom Create Another Voltage with Excitation Channel Channel? Hardware Timing/Triggering? Further Configure Channels? Adjust Timing Settings...

  • Page 88: General Discussion Of Typical Flowchart

    Chapter 5 Using the SCXI-1520 General Discussion of Typical Flowchart The following sections briefly discuss some considerations for a few of the steps in Figure 5-1. These sections are meant to give an overview of some of the options and features available when programming with NI-DAQmx.

  • Page 89: Configuring Channel Properties

    Configuring Channel Properties All ADEs used to configure the SCXI-1520 access an underlying set of NI-DAQmx properties. Table 5-1 shows some of these properties. You can use Table 5-1 to determine what kind of properties you need to set to configure the module for your application.
  • Page 90 Chapter 5 Using the SCXI-1520 Table 5-1. NI-DAQmx Properties (Continued) Property Short Name Description Analog Input»General Properties» AI.Lowpass.CutoffFreq Specifies in hertz Filter»Analog Lowpass»Cutoff the frequency Frequency corresponding to the –3 dB cutoff of the filter. You can specify 10, 100, 1000, or 10000.

  • Page 91: Performing Offset Null Compensation

    ADE help file. Performing Offset Null Compensation The SCXI-1520 provides offset null compensation circuitry to adjust signal voltages to proper levels when the strain gauge or bridge sensor is at rest (unstrained). For most sensors, offset null compensation removes an initial voltage offset from the Wheatstone bridge.

  • Page 92: Performing Shunt Calibration

    Some custom scaling applications require the actual excitation voltage applied to the bridge instead of the nominal excitation voltage output by the SCXI-1520. You can scan the remote sense pins RSX+ and RSX– with the DAQmx physical channels to find the...

  • Page 93: Completing The Application

    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 configure the channels of the SCXI-1520. If you need more information or for further instructions, select Help»VI, Function, & How-To Help from the LabVIEW menu bar.
  • Page 94 Chapter 5 Using the SCXI-1520 Table 5-2. Programming a Task in LabVIEW (Continued) Flowchart Step VI or Program Step Create AI Strain Channel (AI Voltage by default, DAQmx Create Virtual Channel.vi (optional) to change to a strain gauge channel, click AI Voltage and select Analog Input»Strain»Strain Gage.)—This VI is optional if...

  • Page 95: Using A Daqmx Channel Property Node In Labview

    Clear Task DAQmx Clear Task.vi Using a DAQmx Channel Property Node in LabVIEW With the SCXI-1520, you must use property nodes to disable SS/H. Note You can use property nodes in LabVIEW to manually configure the channels. To create a LabVIEW property node, complete the following steps: Launch LabVIEW.

  • Page 96: Specifying Channel Strings In Ni-Daqmx

    SCXI-1520 channels. The input control/constant has a pull-down menu showing all available external channels. You can right-click the physical channel input, select I/O Name Filtering, and check Internal Channels. This allows you to select the SCXI-1520 excitation channels. The strings take one of the following forms: •...
  • Page 97 SCXI-1520 channel—for example SC1Mod1/_pPos0 SC1Mod1/_pNeg0 When you have a task containing SCXI-1520 channels, you can set the properties of the channels programmatically using the DAQmx Channel Property Node. Follow the general programming flowchart or open an example to build a basic strain virtual channel.

  • Page 98: Text Based Ades

    Figure 5-1. You can then use the appropriate function calls to modify the task. This example creates a new task and configures an NI-DAQmx strain channel on the SCXI-1520. You can use the same functions for Visual Basic .NET and C#.
  • Page 99 Chapter 5 Using the SCXI-1520 System.Double maxVal, AIStrainGageConfiguration strainGageConfiguration, AIExcitationSource excitationSource, System.Double excitationValue, System.Double gageFactor, System.Double initialBridgeVoltage, System.Double normalGageResist, System.Double poissonRatio, System.Double leadWireResist, AIStrainUnits units); To actually create and configure the channel, you would enter something resembling the following example code: Task myTask = new NationalInstruments.DAQmx.Task(“myTaskName”);...

  • Page 100: Programmable Ni-Daqmx Properties

    All of the different ADEs that configure the SCXI-1520 access an underlying set of NI-DAQmx properties. Table 5-3 provides a list of some of the properties that configure the SCXI-1520. You can use this list to determine what kind of properties you need to set to configure the device for your application.
  • Page 101 Chapter 5 Using the SCXI-1520 Table 5-3. NI-DAQmx Properties (Continued) Property Short Name Description Analog Input»General Properties» AI.Bridge.ShuntCal.Select Specifies which Signal Conditioning»Bridge» calibration switch(es) to Shunt Cal»Shunt Cal Select enable. Analog Input»General Properties» AI.Excit.Src Specifies the source of Signal Conditioning»Excitation»...

  • Page 102: Developing Your Application In Traditional Ni-Daq (Legacy)

    7.0 or later of an NI ADE. This section describes how to configure and use Traditional NI-DAQ (Legacy) to control the SCXI-1520 in LabVIEW, LabWindows/CVI, Measurement Studio, and other text-based ADEs. These NI ADEs provide...

  • Page 103: Traditional Ni-Daq (Legacy) In Labview

    The strain virtual channel provides scaling for strain gauges, provides an easy interface for offset null compensation and shunt calibration, and allows you to select any name for the SCXI-1520 strain channel that you choose without additional code. When you use virtual channels, the maximum number of channels per E Series DAQ device is 512 in multichassis systems.

  • Page 104: Typical Program Flow

    Typical Program Flow After you have determined how you want to address the channels and whether you want to configure the SCXI-1520 in MAX or LabVIEW, you can design your application using a typical program flow such as the one shown in Figure 5-3.

  • Page 105: Figure 5-3. Typical Scxi-1520 Program Flow With

    SCXI Strain Null.vi Shunt Calibration Perform Shunt Procedure Calibration? Start Acquisition Take Measurements Continue Sampling? Scale, Analyze, and Display Clear Acquisition Error Handling Figure 5-3. Typical SCXI-1520 Program Flow with Traditional NI-DAQ (Legacy) © National Instruments Corporation 5-21 SCXI-1520 User Manual...

  • Page 106: Configuring The Scxi-1520 Settings Using Traditional Ni-Daq (Legacy) In Labview

    AI Parameter VI is only valid for the LabVIEW session and does not change the setting in MAX. You can use the AI Parameter VI to configure the SCXI-1520 settings shown in Table 5-4. Table 5-4. Settings for Configuring the SCXI-1520 Through the AI Parameter...
  • Page 107 SCXI Shunt B Boolean In (T/F) TRUE turns switch ON Enable Enabled FALSE turns switch OFF An example of using the AI Parameter VI to control an SCXI-1520 is shown in Figure 5-4. © National Instruments Corporation 5-23 SCXI-1520 User Manual...

  • Page 108: Performing Offset Null Compensation Using Traditional Ni-Daq (Legacy) In Labview

    Using the SCXI-1520 Above settings become active when this AI Start is executed. Figure 5-4. Using the AI Parameter VI to Set Up the SCXI-1520 Performing Offset Null Compensation Using Traditional NI-DAQ (Legacy) in LabVIEW The SCXI-1520 provides offset null compensation to adjust signal voltages to remove an initial signal voltage offset from the Wheatstone bridge sensor.
  • Page 109 Traditional NI-DAQ (Legacy), use the LabVIEW AI Parameter VI. An example of using the AI Parameter VI to control an SCXI-1520 is shown in Figure 5-4. For more information and example programs for setting the offset null...

  • Page 110: Performing Shunt Calibration Using Traditional Ni-Daq (Legacy) In Labview

    500 ms of data after the switches are closed since the filters in the SCXI-1520 are not fully stabilized until 500 ms have elapsed. You can find the AI Parameter VI in the function subpalette Data Acquisition»Analog Input»Advanced Analog Input.

  • Page 111: Configure, Start Acquisition, And Take Readings Using Traditional Ni-Daq (Legacy) In Labview

    NI-DAQ (Legacy) in LabVIEW After you have performed an offset null compensation, shunt calibration, and configured the SCXI-1520 settings for your application, you can use the intermediate analog input functions AI Config VI, AI Start VI, AI Read VI, and AI Clear VI to create your data acquisition application. You can find the intermediate data acquisition Traditional NI-DAQ (Legacy) functions in the function subpalettes Data Acquisition»Analog Input.

  • Page 112: Analyze And Display Using Traditional Ni-Daq (Legacy) In Labview

    You also can use the LabVIEW Help for more detailed information about how to use the analysis VIs. In LabVIEW, you also can easily display SCXI-1520 measurements with a variety of graphical waveform graphs, numeric slides, gauges, and other indicators.

  • Page 113: Low-Level Daq Functions

    Measurement Studio, you also can write advanced applications using the same low-level DAQ functions guidelines. Low-Level DAQ Functions If you are a new SCXI-1520 user, NI recommends that you use the NI-DAQmx API Notes rather than the Traditional NI-DAQ (Legacy) C API. NI-DAQmx is the second generation data acquisition driver optimized for ease of use and improved performance.

  • Page 114: Figure 5-5. Offset Null And Shunt Calibration Flowchart

    Chapter 5 Using the SCXI-1520 Analyze and display the data. Clear the acquisition. Reset Hardware Perform Configure Offset Null? Acquisition Settings Perform Offset Null Configure Compensation Module Settings Configure Perform Shunt Acquisition Settings Calibration? Configure Module Settings Acquire and Calculate...

  • Page 115: Configuring System Settings Using Traditional Ni-Daq (Legacy) C Api

    Using the SCXI-1520 Configuring System Settings Using Traditional NI-DAQ (Legacy) C API Start the configuration of the acquisition by ensuring that the SCXI-1520 module and SCXI chassis are in their default states, and that the driver software configuration matches the states the actual physical hardware configuration.

  • Page 116: Configuring Module Settings Using Traditional Ni-Daq (Legacy) C Api

    Chapter 5 Using the SCXI-1520 Table 5-5. Configuration Functions (Continued) Function Description Initializes multiplexing circuitry for a scanned data acquisition SCXI_SCAN_Setup operation. Initialization includes storing a table of the channel sequence and gain setting for each channel to be digitized (MIO and AI devices only).

  • Page 117: Table 5-6. Ni-Daq Functions Used To Configure Scxi-1520

    Chapter 5 Using the SCXI-1520 Table 5-6. NI-DAQ Functions Used to Configure SCXI-1520 Channel Significant Possible Setting NI-DAQ Function to Use Parameters Parameters Values Gain 1, 1.15, 1.3, 1.5, 1.8, SCXI_Set_Gain gain (gain setting) 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,...

  • Page 118: Performing Offset Null Compensation Using Traditional Ni-Daq (Legacy) C Api

    Chapter 5 Using the SCXI-1520 Table 5-6. NI-DAQ Functions Used to Configure SCXI-1520 (Continued) Channel Significant Possible Setting NI-DAQ Function to Use Parameters Parameters Values Bridge 4—Quarter bridge SCXI_Configure_Connection Configuration 5—Half bridge connectionType (type of sensor 6—Full bridge connected to the...

  • Page 119: Performing Acquisition Using Traditional Ni-Daq (Legacy) C Api

    After acquiring raw voltage data from the acquisition functions, most applications require adjustment by device calibration constants for accuracy, scaling measured voltage, analysis, and graphical display. The SCXI-1520 has stored software calibration constants loaded on the module EEPROM that are used to achieve the absolute accuracy specifications.

  • Page 120: Other Application Documentation And Material

    Chapter 5 Using the SCXI-1520 After you have adjusted the measurement by the appropriate calibration constants using , you can use a function from the NI SCXI_Scale conversion library to convert a voltage or voltage buffer from convert.h a strain gauge to units of strain. NI-ADEs also provide many powerful analysis functions to perform digital filtering, harmonic analysis, averaging, and complex mathematics on measurements.

  • Page 121: Calibrating The Strain System

    Calibrating the SCXI-1520 The SCXI-1520 is shipped with a calibration certificate and is calibrated at the factory to the specifications described in Appendix A, Specifications. Calibration constants are stored inside the calibration EEPROM and provide software correction values your application development software uses to correct the measurements for offset errors in the module.

  • Page 122: Internal Calibration Using Labview

    Select internal calibration (0) as the operation you are going to perform. The SCXI-1520 takes a few seconds to perform the calibration. After completion, the module has new calibration constants stored for all gain settings. You must repeat the procedure to calibrate other channels in the module.

  • Page 123: Calibrating The System

    Chapter 5 Using the SCXI-1520 Calibrating the System You should perform offset null compensation or shunt calibration on transducers in the system to improve accuracy. This is considered system, or end-to-end, calibration. Offset Null Compensation Performing an offset null compensation removes offset in the measurement system.
  • Page 124 Specifications This appendix lists the specifications for the SCXI-1520 modules. These specifications are typical at 25 °C unless otherwise noted. Analog Input Number of channels ....... 8 Voltage gain settings......X1 to X1000 with the following gain settings: 1; 1.15; 1.3; 1.5;...

  • Page 125: Appendix A Specifications

    Appendix A Specifications SCXI-1520 User Manual ni.com...
  • Page 126 Appendix A Specifications © National Instruments Corporation SCXI-1520 User Manual...
  • Page 127 Bandwidth, filter bypassed .....–3 dB at 20 kHz Simultaneous Sample and Hold Acquisition time Settle to 0.012%.......7 μs Settle to 0.003%.......10 μs Settle to 0.0015%......50 μs Hold mode settling time ......1 μs typ Interchannel skew ........200 ns typ SCXI-1520 User Manual ni.com...
  • Page 128 ..........29 mA Short-circuit protection ......Yes Regulation ..........No load to 120 Ω load With remote sense......±0.003% Without remote sense...... ±0.08% Temperature drift ........±0.005%/°C, ±30 μV/°C max © National Instruments Corporation SCXI-1520 User Manual...

  • Page 129: Power Consumption

    Shunt calibration resistors are in the SCXI-1314 terminal block and are socketed. Resistors shipped with the SCXI-1314 are 100 kΩ RN-55 style (standard 1/8 W size). The tolerance is ±0.1% and the temperature coefficient is 10 ppm/°C max. SCXI-1520 User Manual ni.com...
  • Page 130 Environmental Operating temperature......0 to 50 °C Storage temperature ....... –20 to 70 °C Humidity ..........10 to 90% RH, noncondensing Maximum altitude ........2,000 m Pollution Degree (indoor use only) ..2 © National Instruments Corporation SCXI-1520 User Manual...

  • Page 131: Electromagnetic Compatibility

    Refer to the product Declaration of Conformity (DoC) for additional regulatory compliance information. To obtain product certifications and the DoC for this product, visit , search by model ni.com/certification number or product line, and click the appropriate link in the Certification column. SCXI-1520 User Manual ni.com...
  • Page 132 Waste Electrical and Electronic Equipment (WEEE) At the end of the life cycle, all products must be sent to a WEEE recycling EU Customers center. For more information about WEEE recycling centers and National Instruments WEEE initiatives, visit ni.com/environment/weee National Instruments...

  • Page 133: Traditional Ni-Daq (Legacy) 7.0

    The slots in a chassis are numbered from left to right starting with 1. © National Instruments Corporation SCXI-1520 User Manual...

  • Page 134: Appendix B Using Scxi Channel Strings With Traditional Ni-Daq (Legacy)

    E Series DAQ device to be automatically set to fit the input limits parameter. When this specifier is omitted, the default gain on the DAQ device, usually the lowest gain, is used, but the SCXI-1520 gain is adjusted to fit the input limits. NI recommends using the specifier.
  • Page 135 The measured amplifier offset is for the entire signal path including the SCXI module and the E Series DAQ device. To read the grounded amplifier on the SCXI-1520 use the standard SCXI string syntax in the channels array with...
  • Page 136 Refer to the Calibrating the Strain System section of Chapter 5, Using the SCXI-1520, for more information about how to use SCXI Calibrate VI with the SCXI-1520. SCXI-1520 User Manual ni.com...

  • Page 137: Removing The Scxi-1520

    Power off the chassis. Do not remove the SCXI-1520 module from a chassis that is powered on. If the SCXI-1520 is the module cabled to the E/M Series DAQ device, disconnect the cable. © National Instruments Corporation SCXI-1520 User Manual...

  • Page 138: Appendix C Removing The

    Rotate the thumbscrews that secure the SCXI-1520 to the chassis counterclockwise until they are loose, but do not completely remove the thumbscrews. Remove the SCXI-1520 by pulling steadily on both thumbscrews until the module slides completely out. ｮ 1 Cable...
  • Page 139 Common Questions This appendix lists common questions related to the use of the SCXI-1520. Which version of NI-DAQ works with the SCXI-1520, and how do I get the most current version of NI-DAQ? You must have NI-DAQ 7.0 or later. Visit the NI Web site at ni.com...

  • Page 140: Table D-1. Digital Signals On The Scxi-1520

    Appendix D Common Questions If the SCXI-1520 module is not cabled directly to a E/M Series DAQ device, can I measure conditioned signals for channels 0 through 7 at the rear connector, for example using a scope, DMM, or custom acquisition system? NI does not support or recommend this usage.
  • Page 141 In LabVIEW, can I use a VI to change my SCXI-1520 configuration settings? Yes. You can use the AI Parameter VI to change all the SCXI-1520 configuration settings. You also can change the configuration settings in NI-DAQmx using NI-DAQmx Tasks. Refer to Chapter 5, Using the SCXI-1520, for more information.
  • Page 142 Appendix D Common Questions Can I use the SCXI-1520 with a version of NI-DAQ that works under the Macintosh Operating System (Mac OS)? No, as of NI-DAQ 6.6.1. Check the release notes of later versions of NI-DAQ at for updates.
  • Page 143 What should I take into consideration when I take measurements from sensors with external excitation? Set the SCXI-1520 internal excitation to the closest value to match the external excitation level. If you want to perform offset null compensation, you must set the excitation level to a value other than zero.
  • Page 144 PFI 0. Verify that your E/M Series DAQ device supports analog triggering. For more information about analog triggering with the SCXI-1520, refer to the Analog Hardware Triggering using SCXI and using the info code KnowledgeBase by going to ni.com/info...
  • Page 145 Numbers/Symbols percent positive of, or plus – negative of, or minus ± plus or minus < less than > greater than ° degree ε strain ε simulated strain υ Poisson’s ratio © National Instruments Corporation SCXI-1520 User Manual...
  • Page 146 AI SAMP HOLD TRIG. AI SAMP CLK HOLD TRIG. amplifier amplification A type of signal conditioning that improves accuracy in the resulting digitized signal by increasing signal amplitude relative to noise. ANSI American National Standards Institute SCXI-1520 User Manual ni.com...
  • Page 147 Common-Mode Rejection Ratio—A measure of the ability of a differential amplifier to reject interference from a common-mode signal, usually expressed in decibels (dB). common-mode voltage. common-mode noise Noise that appears on both inputs of a differential amplifier. © National Instruments Corporation SCXI-1520 User Manual...
  • Page 148 = 20log V1/V2, for signals in volts. Direct Current device A plug-in data acquisition board, module, card, or pad that can contain multiple channels and conversion devices. SCXI-1520 User Manual ni.com...
  • Page 149 Supplying a voltage or current source to energize an active sensor or circuit. EXTCLK external clock signal external trigger A voltage pulse from an external source that causes a DAQ operation to begin. EXTSTROBE* CLK. © National Instruments Corporation SCXI-1520 User Manual...
  • Page 150 The time it takes for a sample-and-hold circuit to switch from sampling settling time mode to hold mode and settle within a given percentage at the true hold value. hold step The difference in the true hold value and the measured hold value in a sample-and-hold circuit. SCXI-1520 User Manual ni.com...
  • Page 151 The largest difference in hold mode settling time between two sample-and-hold circuits on the same module. intermodule skew The largest difference in hold mode settling time between two sample-and-hold circuits on different modules. © National Instruments Corporation SCXI-1520 User Manual...
  • Page 152 MIO device Refers to the multifunction I/O E/M Series DAQ devices that have MIO or 60XX in their names. MISO Master-In-Slave-Out signal MOSI Master-Out-Slave-In signal multiplex To route one of many input signals to a single output. SCXI-1520 User Manual ni.com...
  • Page 153 The provision in strain-gauge signal conditioning hardware to remove the compensation unwanted offset voltage present at the output of a strain-gauge bridge when no strain is applied. overvoltage protection Maximum voltage that does not cause hardware damage. © National Instruments Corporation SCXI-1520 User Manual...
  • Page 154 The bridge completion resistor in series with the active strain gauge in a completion resistor quarter-bridge configuration; the quarter-bridge completion resistor must have the same nominal resistance value as the strain gauge. SCXI-1520 User Manual G-10 ni.com...
  • Page 155 RTSI bus Real-Time System Integration bus—The NI timing bus that connects an E/M Series DAQ device directly, by means of connectors on top of the devices, for precise synchronization of functions. seconds samples © National Instruments Corporation G-11 SCXI-1520 User Manual...
  • Page 156 SER DAT IN and SER DAT OUT lines. SER DAT IN serial data input signal SER DAT OUT serial data output signal settling time The amount of time required for a voltage to reach its final value within specified accuracy limits. SCXI-1520 User Manual G-12 ni.com...
  • Page 157 Synchronization pulse for scanning (only used with modules featuring simultaneous sample and hold). system noise A measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded. © National Instruments Corporation G-13 SCXI-1520 User Manual...
  • Page 158 A source that supplies the voltage needed by a sensor for its proper operation.     --------- - --------- - –     STRAINED UNSTRAINED volts, root mean square SCXI-1520 User Manual G-14 ni.com...
  • Page 159 The highest voltage with respect to ground that should be applied to an input terminal during normal use, normally well under the breakdown voltage for safety margin. Includes both the signal and common-mode voltages. © National Instruments Corporation G-15 SCXI-1520 User Manual...
  • Page 160 A-1 excitation level, 3-2 analog triggering, D-6 filter bandwidth, 3-2, 4-25 gain, 3-3, 4-24 null potentiometers, 3-4 connecting SCXI-1520 to DAQ device. See block diagram, 4-19 DAQ devices bridge completion specifications, A-6 conventions used in the manual, iv bridge configuration...
  • Page 161 DAQ device for remote sense, 2-9 multiplexed scanning multiplexed mode operation in PXI combination chassis, 1-5 connecting to SCXI-1520 for DAQ device in SCXI chassis, 1-5 in PXI combination, 1-5 into SCXI chassis, 1-5 in SCXI chassis, 1-5...
  • Page 162 SCXI chassis questions about, D-4 connecting SCXI-1520 to DAQ device, 1-5 removing SCXI-1520, C-1 SCXI-1200, D-2 operation of SCXI-1520. See theory of SCXI-1310 connector and shell assembly, 1-3 operation SCXI-1314 terminal block, 1-2, D-5 SCXI-1314T terminal block, 1-2, D-6 SCXI-1520...
  • Page 163 II, 2-7, 4-14 full-bridge configuration III, 2-8, 4-16 verifying and self-testing the configuration half-bridge configuration I, 2-4, 4-9 troubleshooting, 1-7, D-1 half-bridge configuration II, 2-5, 4-11 quarter-bridge configuration I, 2-1, 4-4 quarter-bridge configuration II, 2-2, 4-6 SCXI-1520 User Manual ni.com...

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