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National Instruments Module SCXI-1125 User's Manual

1. Figure 2 4 Connecting a Ground Referenced AC Coupled Signal 2 4 ni com Chapter 2 Connecting Signals The value of the bias resistor should be between 100 kQ and 1 MQ An added DC offset voltage results due to input bias current flowing through the bias resistor For example with a 1 MQ bias resistor and the specified maximum input bias current of 1 nA you have a maximum added input offset voltage of 1 mV in addition to the initial offset voltage Since only the AC signal is of interest when AC coupling you can choose to remove the DC offset in software by using a simple highpass filter UN Caution Pins A2 A4 A8 C2 C4 C6 and C8 on the front signal connector are not isolated and do not have the same protection circuitry as the positive and negative analog input pairs discussed in the Floating Signal section Hooking up external signals to these pins can damage the SCXI 1125 module Pin Assignments The front signal connector is a special 32 pin DIN C male front connector used for connecting analog input signals including the CJC to the analog circuitry of the SCXI 1125 This connection allows access to the eight differential analog input signals The positive terminal is Alx and the negative terminal AIx A missing pin exists between two consecutive input channels to meet the UL spacing requirements for high voltage signals CJ TEMP is the signal connection used by the cold junction channel on the SCXI 1125 T
2. National Instruments Corporation 3 1 SCXI 1125 User Manual Chapter 3 Configuring and Testing Connecting the SCXI 1125 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCXI Quick Start Guide to install the cable adapter and connect the SCXI modules to the DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1125 module s Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCXI Quick Start Guide to connect the SCXI modules to the DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1125 module s Configurable Settings in MAX 3 Note Ifyou are not using an NI ADE using an NI ADE prior to version 7 0 or are using 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 These messages continue to appear until you install version 7 0 or later of an NI ADE This section describes where users can access each software configurable setting for modification in MAX The location of the settings varies depending on the version of NI DAQ you use Refer to either the NI DAQmx section or the Traditional NI DAQ Legacy section You also can refer to the DAQ Getting St
3. National Instruments Corporation 5 5 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 es No Create Task Using DAQ Assistant y Create Task in DAQ Assistant or MAX Create Another Channel Y Create a Task Programmatically Create Channel Application Specific Hardware Further Configure Channels Configure Channels Timing Triggering Adjust Timing Settings Start Measurement Read Measurement A Process Data Graphical Display Tools y Analyze Data Display Data No Yes Clear Task Continue Sampling Stop Measurement Figure 5 1 Typical Program Flowchart SCXI 1125 User Manual 5 6 ni com Chapter 5 Using the SCXI 1125 General Discussion of Typical Flowchart The following sections discuss briefly considerations for a few of the steps in Figure 5 1 These sections give an overview of some of the options and features available when programming with NI DAQmx Creating a Task Using DAQ Assistant or Programmatically When creating an application first you must decide whether to create the appropriate task using the DAQ Assistant or programmatically in the ADE Developing your application using DAQ Assistant gives you the ability to configure most settings such as measurement type selection of channels excitation voltage signal input limits
4. eee ee eeeeseeeeceeeeeeenseteeeeseeaees 5 29 Traditional NI DAQ Legacy CVI Examples 00 eee cee ec eeeeeeeeeeeereeeeaee 5 29 Traditional NI DAQ Legacy Measurement Studio Examples 0 00 5 29 Calibration eo 22st naciiciu osease saa EE elena en Saintes stein Aad anaes 5 30 Calibration Procedures siiis iscissi aiaa a aro asi 5 30 One Point Offset Calibration eee eseeseceeeeseeneeeseteeenseesees 5 31 Two Point Gain and Offset Calibration eee eeeeseeeeeereeees 5 32 National Instruments Corporation vij SCXI 1125 User Manual Contents Appendix A Specifications Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later Appendix C Removing the SCXI 1125 Appendix D Common Questions Glossary Index Figures Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 4 1 Figure 5 1 Figure 5 2 Figure 5 3 Figure 5 4 Figure A 1 Figure C 1 SCXI 1125 User Manual Connecting a Ground Referenced Signal 0 eee eeeeseeeeeeeereeees Connecting a Floating Signal eee ceceseeeeceeceeeeseeeseeeeeseeaeees Connecting a Floating AC Coupled Signal 0 eeeeeeeeeeeeeees Connecting a Ground Referenced AC Coupled Signal SCXI 1125 Block Diagram eee eee eeeeseceeeeeeseeeseeneeeseeneeeaeeseenaes Typical Program Flowchart 0 cescescesceceseceseeeeeeeseeeeeeceeersaeeeaeeues LabVIEW Channel Property Node with Lowpass Frequency Set at 10 kHz on Channel SC1
5. Verifying the Signal Using Channel Strings The format of the channel string is as follows obx scy mdz channel where obx is the onboard E Series DAQ device channel with x representing a particular channel where the multiplexed channels are sent This value is 0 for E Series DAQ device channel 0 in a single chassis system In a multichassis or remote chassis system the E Series DAQ device channel x corresponds to chassis number n 1 where E Series DAQ device channel x is used for scanning the nth chassis in the system scy is the SCXI chassis ID where y is the number you chose when configuring the chassis mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right starting with 1 channel is the channel that is sampled from module z Use the format obx scy mdz n to verify the signal where n is a single input channel National Instruments Corporation 3 7 SCXI 1125 User Manual Chapter 3 Configuring and Testing Complete the following steps to use channel strings in verifying the signal Expand Devices and Interfaces Expand Traditional NI DAQ Devices Right click the appropriate E Series DAQ device Click Test Panels Enter the channel string Enter the input limits Select the Data Mode Select the Y Scale Mode CO ON a et as D Refer to the LabVIEW Measurements Manual for more information and for
6. electromechanical compliance electromagnetic interference G 4 ni com F filtering FSR gain gain accuracy gain error GND T O in input bias current input impedance National Instruments Corporation G 5 Glossary A type of signal conditioning that allows you to remove unwanted signal components from the signal you are trying to measure full scale range The factor by which a signal is amplified sometimes expressed in decibels A measure of deviation of the gain of an amplifier from the ideal gain See gain accuracy ground hertz input output The transfer of data to from a computer system involving communications channels operator interface devices and or data acquisition and control interfaces inch The current that flows into the inputs of a circuit The measured resistance and capacitance between the input terminals of a circuit SCXI 1125 User Manual Glossary isolation isothermal L linearization M TEMP max min MIO multiplex SCXI 1125 User Manual A type of signal conditioning in which you isolate the transducer signals from the computer for safety purposes Isolating the signals protects you and your computer from large voltage spikes and makes sure the measurements from the DAQ device are not affected by differences in ground potentials Maintenance of constant temperature across an area Isothermal construction of terminal blocks increases thermocouple
7. gt ActiveChans bAT Lowpass CutoffFreq 4 5C1Mod1 ai0 Figure 5 2 LabVIEW Channel Property Node with Lowpass Frequency Set at 10 kHz on Channel SC1Mod1 ai0 9 To add another property to the property node right click an existing property and left click Add Element To change the new property left click it and select the property you wish to define B Note Refer to the LabVIEW Help for information about property nodes and specific NI DAQmx properties Specifying Channel Strings in NI DAQmx SCXI 1125 User Manual Use the channel input of DAQmx Create Channel to specify the SCXI 1125 channels The input control constant has a pull down menu showing all available external channels The strings take one of the following forms e single device identifier channel number for example SC1Mod1 ch0 e multiple noncontinuous channels for example SC1Mod1 ch0 SC1Mod1 ch4 e multiple continuous channels for example SC1Mod1 ch0 4 channels 0 through 4 e cold junction channel Sc1Mod1 _cjtemp When you have a task containing SCXI 1125 channels you can set the properties of the channels programmatically using the DAQmx Channel Property Node 5 12 ni com Chapter 5 Using the SCXI 1125 Follow the general programming flowchart or open an example to build a basic virtual channel You can use property nodes in LabVIEW to control configure and customize the NI DAQm x task and SCXI 1125 To create a LabVIEW pr
8. either 0 or 1 Bayonet Neill Concelman A type of coaxial connector used in situations requiring shielded cable for signal connections and or controlled impedance applications G 2 ni com CE CH channel chassis CJ TEMP CJC CLK CMRR code width cold junction compensation common mode voltage cutoff frequency D A D A D GND National Instruments Corporation G 3 Glossary Celsius Conformit Europ enne The European emissions control standard The CE mark certifies that a product complies to relevant CE regulations CE is a common standard for all countries in the EU European Union channel Pin or wire lead to which you apply or from which you read an analog or digital signal Analog signals can be single ended or differential For digital signals channels group to form ports Ports usually consist of either four or eight digital channels The enclosure that houses powers and controls SCXI modules cold junction temperature sensor signal cold junction compensation clock input signal common mode rejection ratio A measure of the capability of an instrument to reject a signal that is common to both input leads The smallest detectable change in an input voltage of a DAQ device A method of compensating for inaccuracies in thermocouple circuits Voltage that appears on both inputs of a differential amplifier The frequency at which the filter attenuates the input 3 dB or half of i
9. meaning channels can be in any order and occur multiple times in a single scan When performing multiple scans the list pointer of the module automatically wraps around and starts scanning with the first channel in the scan list Operating in Parallel Mode You can configure the SCXI 1125 to operate in parallel mode as described in Chapter 1 About the SCXI 1125 In parallel mode all eight analog output channels on the SCXI 1125 are connected to eight analog input channels on the E M Series DAQ device The CJC channel is not accessible Every SCXI 1125 configured for parallel mode must have a E M Series DAQ device directly cabled to it National Instruments Corporation 4 3 SCXI 1125 User Manual Chapter 4 Theory of Operation Theory of Parallel Hardware Operation In parallel mode the CHO signal on the rear signal connector is configured as the output of the SCXI 1125 analog input channel 0 The rear signal connector carries each of the analog outputs of the SCXI 1125 to the connected DAQ device You can use an SCXI 1180 feedthrough connector to make each of the outputs available at the front of the chassis which is useful for cascading these signals to other modules for additional signal conditioning purposes Parallel mode allows you to bypass scanning and you are not limited by the settling time required by the multiplexer of SCXI 1125 You can scan the channels more accurately at a faster rate depending on which E M Series DAQ d
10. s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of 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 Trademarks National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com legal for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies Members of the National Instruments Alliance Partner Program are business entities independent from National Instruments and have no agency partnership or joint venture relationship with National
11. 1125 module and SCXI chassis are in their default states and that the driver software configuration matches the states the actual physical hardware configuration After setting the hardware and software to the defaults of the module s you can configure any module settings that vary from the default configuration settings You also should configure the acquisition parameters using the functions in Table 5 7 For additional information such as the function prototypes parameters and usage instructions for each function refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ National Instruments Corporation 5 21 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Table 5 7 Configuration Functions Function Description SCXI_Reset Resets the hardware such as the specified module to its default state You also can use SCXI_Reset to reset the SCXI chassis Slot 0 scanning circuitry or reset the entire chassis The SCXI 1125 default conditions are e Gain set at 1000 0 e 4Hz lowpass filter SCXI_Load_Config Loads the SCXI chassis configuration information you established in MAX Sets the software states of the chassis and the modules present to their default states This function makes no changes to the hardware state of the SCXI chassis or modules It is possible to programmatically change the configuration you established in MAX using the
12. 5 Using the SCXI 1125 Text Based ADEs You can use text based ADEs such as LabWindows CVI Measurement Studio Visual Basic NET and C to create code for using the SCXI 1125 LabWindows CVI LabWindows CVI works with the DAQ Assistant in MAX to generate code for a task You can then use the appropriate function call to modify the task To create a configurable channel or task in LabWindows CVI complete the following steps 1 Launch LabWindows CVI 2 Open a new or existing project 3 From the menu bar select Tools Create Edit DAQmx Tasks 4 Choose Create New Task In MAX or Create New Task In Project to load the DAQ Assistant 5 Configure the NI DAQmx task following the instructions in the Creating a Voltage Global Channel or Task section 6 The DAQ Assistant creates the code for the task based on the parameters you define in MAX and the device defaults To change a property of the channel programmatically use the DAQmxSetChanAttribute function 3 Note Refer to the NI LabWindows CVI Help for more information on creating NI DAQmx tasks in LabWindows CVI and NI DAQmx property information Measurement Studio Visual Basic NET and C SCXI 1125 User Manual When creating a task in Visual Basic NET and C follow the general programming flow in 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 channel on the SCXI 112511251125
13. Clear Task vi Using a DAQmx Channel Property Node in LabVIEW You can use property nodes in LabVIEW to manually configure the channels To create a LabVIEW property node complete the following steps 1 Launch LabVIEW 2 Create the property node in a new VI or in an existing VI 3 Open the block diagram view 4 From the Functions toolbox select Measurement I O DAQnmx Data Acquisition and select DAQmx Channel Property Node 5 Use the ActiveChans box to specify exactly what channel s you want to configure If you want to configure several channels with different properties separate the lists of properties with another ActiveChans box and assign the appropriate channel to each list of properties ay Note If you do not use Active Channels the properties are set on all of the channels in the task 6 Right click ActiveChans and select Add Element Left click the new ActiveChans box Navigate through the menus and select the property you wish to define National Instruments Corporation 5 11 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 7 Change the property to read or write to either get the property or write a new value Right click the property go to Change To and select Write Read or Default Value 8 After you have added the property to the property node right click the terminal to change the attributes of the property add a control constant or indicator R t DAQmx Channel A
14. GND 7 RSVD means no pin 1 SCXI 1125 User Manual 2 6 ni com Chapter 2 Connecting Signals Temperature Sensor Connection Pin C4 on the front signal connector is used to connect to a terminal block temperature sensor The temperature sensor channel is not isolated and is referenced to the chassis ground The connection is overvoltage protected to 25 VDC with power on and 15 VDC with power off Rear Signal Connector The rear signal connector is a 50 pin male ribbon cable connector used for analog signal connectivity and communication between the SCXI 1125 and the connected DAQ device The rear signal connector allows the DAQ device to access all eight differential analog output signals from the SCXI 1125 The positive terminal of each analog output is CH x and the negative terminal CH x Grounding signals AI GND and OUT REF provide reference signals needed in the various analog referencing modes on the E M Series DAQ device In multiplexed mode the CH 0 signal pair is used for sending all eight channels of the SCXI 1125 and other analog signals from other modules to the connected E M Series DAQ device If the module is directly connected to the E M Series DAQ device the other analog channels of the E M Series DAQ device are still unavailable for general purpose analog input because they are still connected to the amplifier outputs of the SCXI 1125 in multiplexed mode The communication signals between the DAQ device
15. NI ADE using an NI ADE prior to version 7 0 or are using 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 These messages continue to appear until you install version 7 0 or later of an NI ADE This section describes how to configure and use Traditional NI DAQ Legacy to control the SCXI 1125 in LabVIEW LabWindows CVI Measurement Studio and other text based ADEs These NI ADEs provide greater flexibility and access to more settings than MAX but you can use ADEs in conjunction with MAX to quickly create a customized application National Instruments Corporation 5 15 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Traditional NI DAQ Legacy in LabVIEW LabVIEW is a graphical programming environment for test and measurement application development with built in easy to use tools for data acquisition analysis and display You can use functional graphical blocks called subVIs to easily create a custom application that fully utilizes the SCXI 1125 programmable functionality Traditional NI DAQ Legacy provides several standard data acquisition subVIs as well as subVIs specifically for use with the SCXI 1125 For applications using Traditional NI DAQ Legacy in LabVIEW there are two typical methods of addressing SCXI 1125 channels virtual channels specifically virtual channels and SCXI channel strings Depending o
16. SCXI_Set_Config function SCXI_SCAN_Setup Initializes multiplexing circuitry for a scanned data acquisition operation Initialization includes storing a table of the channel sequence and gain setting for each channel to be digitized MIO and AI devices only You cannot repeat channels or use nonsequential channels when using the SCXI_SCAN_Setup function SCXI_MuxCtr_Setup Programs the E Series DAQ device with the correct number of channels multiplexed per scan This number must match the total number of channels programmed in SCXI_SCAN_Setup ky Note NI strongly recommends monitoring the built in error status of each NI DAQ function The NI DAQ C API provides the NIDAQErrorHandler function which ensures that a specified NI DAQ function executed properly and assists in handling error messages and reporting Configure Module Settings Using Traditional NI DAQ Legacy C API After configuring the hardware for acquisition you must load the various channel attributes such as filter gain and excitation appropriate for your application explicitly using the NI DAQ function calls shown in Table 5 8 For more information regarding each setting refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ SCXI 1125 User Manual 5 22 ni com Chapter 5 Using the SCXI 1125 Table 5 8 NI DAQ Functions Used to Configure SCXI 1125 Channe
17. and the SCXI system are SER DAT IN SER DAT OUT DAQ D A SLOT 0 SEL SER CLK and AI HOLD COMP AI HOLD The digital ground D GND on pins 24 and 33 provides a separate ground reference for the communication signals SER DAT IN SER DAT OUT DAQ D A SLOT 0 SEL and SER CLK are the communication lines for programming the SCXI 1125 The AI HOLD COMP AI HOLD and SYNC signals are the signals necessary for multiplexed mode scanning If the E M Series DAQ device is connected to the SCXI 1125 these digital lines are unavailable for general purpose digital I O The rear signal pin assignments are shown in Table 2 2 National Instruments Corporation 2 7 SCXI 1125 User Manual Chapter 2 Connecting Signals Table 2 2 Rear Signal Pin Assignments Rear Connector Diagram Signal Name Pin Number Pin Number Signal Name AI GND 1 2 AI GND 1 2 CH 0 3 4 CH0 3 4 CH 1 5 6 CH 1 AE CH2 7 8 CH2 7 8 i 2 9 10 CH 3 9 10 CH3 GURS CH 4 11 12 CH 4 13 14 15116 CH5 13 14 CH5 17 18 CH6 15 16 CH6 19 20 21 22 CH7 17 18 CH7 23 24 OUT REF 19 20 NC 25 26 NC 21 22 NC 27 28 29 30 NC 23 24 D GND 31 32 SER DAT IN 25 26 SER DAT OUT 33 34 35 36 DAQ D A 27 28 NC 37 38 SLOT 0 SEL 29 30 NC cae le NC 31 32 NC 41 42 43 44 D GND 33 34 NC atl ha
18. on programming the SCXI modules for scanning in multiplexed mode Traditional NI DAQ Legacy CVI Examples Many example programs ship with NI DAQ For more example information on how to create tasks and channels refer to the example programs By default the example programs are installed in C Program Files National Instruments CVI x x Samples More examples are installed by default in c Program Files National Instruments NI DAQ Examples Traditional NI DAQ Legacy Measurement Studio Examples Many example programs ship with NI DAQ For more example information on how to create tasks and channels refer to the example programs By default the example programs are installed in C Program Files National Instruments Measurement Studio 7 0 More examples are installed by default in C Program Files National Instruments NI DAQ Examples National Instruments Corporation 5 29 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Calibration The SCXI 1125 is shipped with a calibration certificate and is calibrated by the factory to the specifications described in Appendix A Specifications Calibration constants are stored inside the calibration EEPROM and provide software correction values that are used by your application development software to correct your measurements for both offset and gain errors in the module Due to the nature of the analog circuitry in your SCXI 1125 module gain errors tend to be more stable ove
19. or very similar to the SCXI 1120 Table D 1 Comparison of the SCXI 1125 with the SCXI 1120 Feature SCXI 1120 SCXI 1125 Analog input Input range 8 5 V 250 V with SCXI 1327 8 5 V 300 V with SCXI 1327 1000 VDC with TBX 1316 Isolation 250 Vms 300 Vims Gains 1 2 5 10 20 50 100 200 250 500 1 2 5 10 20 50 100 200 250 500 1000 and 2000 jumper selectable 1000 and 2000 software selectable Filters 4 Hz or 10 kHz jumper selectable 4 Hz or 10 kHz software selectable Autozero Not supported Software configurable and scannable Calibration Manually rotateable potentiometers Software internal one point offset for one point offset calibration calibration software external two point offset and gain calibration and onboard calibration constant storage in EEPROM Scanning 333 kS s with consecutive channels 333 kS s with nonconsecutive and repeating channels random scanning CJC scanning M TEMP non scannable or D TEMP direct channel M TEMP CJ TEMP scannable Offset error 6 uV 3 mV gain 0 2 mV gain typical Gain error 0 2 typ 0 6 max 0 03 typ 0 08 max National Instruments Corporation D 1 SCXI 1125 User Manual Appendix D Common Questions SCXI 1125 User Manual Which version of NI DAQ is needed to work with the SCXI 1125 and how do I get the most current version of NI DAQ You must have NI DAQ 7 0 or later
20. proper formatting of channel strings for different uses Verifying the Signal Using Virtual Channel If you have already created a virtual channel complete the following steps to verify the signal 1 Right click the virtual channel you want to verify and select Test 2 In Channel Names select the channel you want to verify 3 When you have completed verifying the channel click Close SCXI 1125 User Manual 3 8 ni com Theory of Operation The section includes a brief overview and a detailed discussion of the circuit features of the module The two major modes of operation multiplexed and parallel mode are discussed Refer to Figure 4 1 while reading this section Gain Select Lowpass Lowpass AlO Al O E Filter gt Fiter gt A AlO i 5 e Analog e 7 Multiplexer Al 7 amp e Al7 5 e S T ps 3 A Al7 po 5 Scan 3 Z r cc e S Clock c e 2 2 To S Analog Analog re Gain Select Multiplexer Bus Control gt Bus 2 Pio Lowpass Lowpass 8 F Filter D gt Fiter 2 Al 7 J fe YAZ x MTEMP Digital Interface 3 and Control Figure 4 1 SCXI 1125 Block Diagram Gain The SCXI 1125 has 12 different gain settings from 1 to 2000 enabling signal ranges 5 V to 2 5 mV When the SCXI 1125 is
21. x representing a particular channel where the multiplexed channels are sent This value is 0 for DAQ channel 0 in a single chassis system In a multichassis or remote chassis system however the E Series DAQ device channel x corresponds to chassis number n 1 where DAQ device channel x is used for scanning the nth chassis in the system e scy is the SCXI chassis ID where y is the number you chose when configuring your chassis e mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right starting with 1 3 Note The obx specifier is optional and causes the gains on the module and E Series DAQ device to be automatically set to fit the input limits parameter When this specifier is omitted the default gain on the E Series DAQ device usually the lowest gain is used but the SCXI 1125 gain is adjusted to fit the input limits National Instruments Corporation 5 25 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 The last parameter channels is the list of channels that are scanned for module z It can have several formats obx scy mdz n where n is a single input channel e obx scy mdz nI n2 where n1 and n2 represent a sequential list of input channels inclusive e obx scy mdz cjtemp where cjtemp is the CJC channel You can scan this channel with other analog input channels For compatibility reasons you ca
22. you to important information This icon denotes a caution which advises you of precautions to take to avoid injury data loss or a system crash When this symbol is marked on a product refer to the Read Me First Safety and Radio Frequency Interference for information about precautions to take When symbol is marked on a product it denotes a warning advising you to take precautions to avoid electrical shock When symbol is marked on a product it denotes a component that may be hot Touching this component may result in bodily injury Bold text denotes items that you must select or click in the software such as menu items and dialog box options Bold text also denotes parameter names Italic text denotes variables emphasis a cross reference or an introduction to a key concept Italic text also denotes text that is a placeholder for a word or value that you must supply Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions Bold text in this font denotes the messages and responses that the computer automatically prints to the screen This font also emphasizes lines of code that are different from the other examples Italic text in this font denotes tex
23. 25 User Manual Remember that the calibration you perform on the SCXI 1125 is only as accurate as the calibration device you are using Refer to Appendix A Specifications for accuracy specifications for the SCXI 1125 5 30 ni com One Point Offset Calibration Chapter 5 Using the SCXI 1125 To perform offset calibration on your module follow this procedure if you are using LabVIEW 1 Make sure the DAQ device or DMM you are using has a valid calibration and meets the accuracy specifications for your application 2 In LabVIEW use the SCXI Calibrate VI to calibrate your module Enter the DAQ device and the SCXI channel string for the channels you want to calibrate You can calibrate only one channel a e at a time Select internal calibration as the calibration operation you are going to perform Select the Default EEPROM load area as the area you want to update The offset varies with the selected gain value Therefore enter the high and low limits that correspond to the gain value for which you are calibrating offset Refer to Table 5 9 for a list of the gain values and the corresponding input limits you must enter Enter 0 0 as the input reference voltage Run the application 4 Repeat steps 2 through 3 for calibrating the offset for additional channels or gain combinations Table 5 9 Gain Values and Input Limits National Instruments Corporation G
24. CXI 1125 User Manual A 10 ni com Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later 3 Note This appendix is not applicable if you use the virtual channels to configure and measure the SCXI channels Virtual channels are configured using MAX If you use virtual channels you address the SCXI channels by specifying the channel name s in the channel string input When using LabVIEW and Visual Basic the SCXI channel string determines which SCXI channels are scanned and the scanning sequence The SCXI channel string allows you to take measurements from several channels on one module with only one channel string entry An array of these channel string entries configures multiple modules for scanning When the application program runs the channel string is used for programming the channel information into the SCXI system The format of the channel string is as follows obx scy mdz channels where e obx is the onboard E M Series DAQ device channel with x representing a particular channel where the multiplexed channels are sent This value is 0 for E M Series DAQ device channel 0 in a single chassis system In a multichassis or remote chassis system the E M Series DAQ device channel x corresponds to chassis number n 1 where E M Series DAQ device channel x is used for scanning the nth chassis in the system e scyis the SCXI chassis ID where y is the number you chose when configuring the chassis e
25. Gain and Range Using the TBX 1316 Overall Input SCXI 1125 TBX 1316 Gain Range Gain Attenuation 0 005 1000 V 1 200 0 01 500 V 2 200 0 025 200 V 5 200 0 05 100 V 10 200 0 1 50 V 20 200 0 25 20 V 50 200 1 25 4V 250 200 The overall input impedance is reduced when attenuating the input but this is acceptable in most applications Refer to terminal block installation guides for more information Appendix A Specifications shows how the analog input specifications are affected with the addition of the SCXI 1327 terminal block Developing Your Application in NI DAQmx 3 Note Ifyou are not using an NI ADE using an NI ADE prior to version 7 0 or are using an unlicensed copy of an NI ADE NI License Manager displays additional dialog boxes so you can create a task or global channel in unlicensed mode These dialog boxes continue to appear until you install version 7 0 or later of an NI ADE This section describes how to configure and use NI DAQmx to control the SCXI 1125 in LabVIEW LabWindows CVI and Measurement Studio These ADEs provide greater flexibility and access to more settings than MAX but you can use ADEs in conjunction with MAX to quickly create a customized application Typical Program Flowchart Figure 5 1 shows a typical program flowchart for creating a task to configure channels take a measurement analyze and present the data stop the measurement and clear the task
26. I Quick Start Guide This document contains a quick overview for setting up an SCXI chassis installing SCXI modules and terminal blocks and attaching sensors It also describes setting up the SCXI system in MAX e The SCXI hardware user manuals Read these manuals next for detailed information about signal connections and module configuration They also explain in greater detail how the module works and contain application hints e Accessory installation guides or manuals If you are using accessory products read the terminal block and cable assembly installation guides They explain how to physically connect the relevant pieces of the system Consult these guides when you are making the connections e The E M Series DAQ device documentation This documentation has detailed information about the E M Series DAQ device that plugs into or is connected to the computer Use this documentation for hardware installation and configuration instructions specification information about the E M Series DAQ device and application hints e 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 If you have a large complex system it is worthwhile to lo
27. Instruments Patents For patents covering National Instruments products refer to the appropriate location Help Patents in your software the patents txt file on your media or ni com patents WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE UNANTICIPATED USES OR MISUSES OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED SYSTEM FAILURES ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY UPO
28. ML AN 0 0 ANT LE MET Asz Eso 80 0 osz AW OZF ANOLT AV LT L700 0 ANTI AN 09 0 ANG LY AN 97 Anoe 75 0 80 0 ooz AW STF Anope AoE L700 0 AN IZ Av ey AN 788 Mi T9 A09 ZSO L00 O01 AW OSF AvloL9 Ato L700 0 AN Ty AN YZ AN OBI ANTI AOI ZSO L00 os AW 00IF AWCg T AEI L700 0 A TOL Atl e9 AN ply Avoze anost zs0 L00 oz AW OSTF AWTE E Av 97 L700 0 AN 707 Av EI AN 78g Av69 Aros 7s 0 L00 ol AW 00S Awg 9 ANTS L700 0 Aq or AN yT AW LT A OTI AWOT TSO L00 S ATIF AWS 9T A 9ZI L700 0 AW TT Av 09 AW gp Aps Awez zso L00 T A SCF AWO E Av IST L700 0 AW TZ AN TTI AW 9 8 Avogs anos 70 L00 I A SF AWO 08 AW 7 Z 6700 0 AW Ty Avgez AWTOI AW AWOT S90 8PszO 50 A OIF AWOOZ AW py 6700 0 AW TT Av I9 AU Sy Awg Awsz s90 8psz0 TO pA STF AWOOr AW TT 6700 0 AW IZ AWET AWII Aug Awos S90 sPrsz0 TO A OSF AWO6L AW 7 6Z00 0 AW Ly AWOZ AW EST AWZI AWOOT 90 srszo so o A 0OLF AOZ AU py 6700 0 AW 00T AWL AW 8Lp Awe6oe AWOST S90 8rSz 0 z0 0 pA OST AO vI AW ZET P 00 0 AW 10P AW SZ AT AWST AWPsg scr 966 0 sooo ezv 1rOdA 0001F AW OJAn D surpeoy ZHA OTL ZH ZH OT 7H PSJO Xew fesd4 y u osuey puuoN 37898 IMA PSO Jo 1181949 ye emy amnjosqy yuq sinjessdugy ISBIIAV urod ABUS SUMELA JO eu3is yeod ISION WIAS S Aseinaasy aynjosqy SCXI 1125 User Manual A 3 National Instruments Corporation Specifications Appendix A YOo q Teura
29. Mod1 ai0 o oo eeseeeeeeeeeneeeeeees Typical SCXI 1125 Program Flow with Traditional NI DAQ Legacy eeeescsseeeeseeeteeeeseeeeesseeeeseeeseees Using the AI Parameter VI to Set Up the SCXI 1125 we SCXI 1125 Dimensions ciscsseiscsedeideesssesceveesssneagsscsdsasasescdssnsesssbaa seaeveed Removing the SCXI 1125 pnsssnrocugan na a ts viii ni com Contents Tables Table 2 1 Front Signal Pin Assignments 00 0 cece eeceeseceeeeseeeseeeeeeeeseeeseseeeeaees 2 6 Table 2 2 Rear Signal Pin Assignments 00 0 ceseeceeseceeeseeeseeseeeeeeseeesetseeeseesees 2 8 Table 5 1 Extended Gain and Range Using the SCXI 1327 or SCXI 1313A 5 4 Table 5 2 Extended Gain and Range Using the TBX 1316 sesers 5 5 Table 5 3 NI DAQmx Properties ee neee a aa a a e A ak 5 8 Table 5 4 Programming a Task in LabVIEW sssseeeseesseesesresesrsrrsrsrrsreererrsreersreee 5 10 Table 5 5 NI DAQmx Propertie Seii a a a a a a a ties 5 15 Table 5 6 Settings for Configuring the SCXI 1125 Through the AI Parameter ee ee rnn a n n e aak 5 18 Table 5 7 Configuration Functions esse er e rrene arr E EEE EEEa ES 5 22 Table 5 8 NI DAQ Functions Used to Configure SCXI 1125 woe 5 23 Table 5 9 Gain Values and Input Limits oo eee ee ese ceeeseeeseeseeeaeeseeeaeens 5 31 Table A 1 Input Signal Range Versus Gain cee eee eeeeseeeeeeeceeeeaeeeeeeseeeeees A 1 Table A 2 Terminal Block Maximum Voltages sesseseeseeeseesrsresrserssrerrersreersreee A 8 Ta
30. N ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE TO AVOID DAMAGE INJURY OR DEATH THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES INCLUDING BUT NOT LIMITED TO BACK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION Conventions 3 A A A bold italic monospace monospace bold monospace italic 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 P0 lt 3 0 gt The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a note which alerts
31. SCXI SCXI 1125 User Manual April 2008 7 NATIONAL 372425801 INSTRUMENTS Worldwide Technical Support and Product Information ni com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 683 0100 Worldwide Offices Australia 1800 300 800 Austria 43 662 457990 0 Belgium 32 0 2 757 0020 Brazil 55 11 3262 3599 Canada 800 433 3488 China 86 21 5050 9800 Czech Republic 420 224 235 774 Denmark 45 45 76 26 00 Finland 358 0 9 725 72511 France 01 57 66 24 24 Germany 49 89 7413130 India 91 80 41190000 Israel 972 3 6393737 Italy 39 02 41309277 Japan 0120 527196 Korea 82 02 3451 3400 Lebanon 961 0 1 33 28 28 Malaysia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210 311 210 Russia 7 495 783 6851 Singapore 1800 226 5886 Slovenia 386 3 425 42 00 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 2005151 Taiwan 886 02 2377 2222 Thailand 662 278 6777 Turkey 90 212 279 3031 United Kingdom 44 0 1635 523545 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 1999 2008 National Instruments Corporation All rights rese
32. Visit ni com and follow the link Download Software Drivers and Updates Search Drivers and Updates and type in the keyword NI DAQ to find the latest version of NI DAQ for your operating system I have gone over the Verifying the SCXI 1125 Installation in Software in Chapter 1 About the SCXI 1125 yet I still cannot correctly test and verify that my SCXI 1125 is working What should I do now Unfortunately there always exists the chance that something is not operating correctly in your system or the combination of the components in your system is not operating correctly together You may now have to call or e mail a technical support representative The technical support representative will often suggest additional troubleshooting measures to try in order to isolate the problem If requesting technical support by phone have your system near at hand so that you can try these measures immediately Can I use the unused analog input channels of the E M Series DAQ device if I am directly cabled to the SCXI 1125 It depends The SCXI 1125 always outputs channels 1 through 7 to the rear signal connector to permit parallel mode scanning If you are using a 16 channel 8 differential inputs E M Series DAQ device all E M Series DAQ channels are unusable for general purpose analog input If you have a module in the chassis that does not have parallel mode connect the E M Series DAQ device to it and use a breakout connector to connect to the un
33. XI 1313A high voltage terminal blocks eee 2 6 kHz 5 With TBX 1316 high voltage terminal blocK eeeeeeeeeneee 500 Hz 5 Slew rate Ty pial ic iiinis oinin 0 15 V us Mimu enisi nnise 0 1 V us Scan interval accuracy SOLO E E a 3 us 40 006 ss sssisseeessorseessserssoressersses 10 us ENO ELA 20 us National Instruments Corporation A 5 SCXI 1125 User Manual Appendix A Specifications Normal Mode Rejection 50 60 Hz NMRR 4 Hz filter enabled Crosstalk at 1kHz Adjacent channels All other channels Input coupling Default Using SCXI 1305 or TBX 1329 Power Consumption 75 dB 90 dB DC AC or DC FLES M ra E eget 140 mA max SPL BIDE erretena e 140 mA max BOON AEE 10 mA max Output Characteristics Output range isoa 5 0 V Output impedance Multiplexed output mode 100 Q Parallel output mode Transfer Characteristics All ran EES ni i deseilieeeds Recommended warm up time Offset drift siasii ae Gran Cri ftat taie Nonlinearity Stability Calibration External calibration interval SCXI 1125 User Manual 330 Q 0 02 of full scale range 15 minutes 0 42 250 gain uV C 20 ppm C typical 1 year ni com Appendix A Specifications Physical 3 0 cm 1 2 in o WM A EBA 0 pee 17 2 cm 6 8 in o 1 Lo aD V EH isao E 7 4 in Figure A 1 SCXI 1125 Dimensions Wel ght csc
34. You can use the same functions for Visual Basic NET and C Programmable NI DAQmx Properties All of the different ADEs that configure the SCXI 1125 access an underlying set of NI DAQm x properties Table 5 5 provides a list of some of the properties that configure the SCXI 1125 You can use this list to determine what kind of properties you need to set to configure the device for your application For a complete list of NI DAQmx properties refer to your ADE help file 5 14 ni com Chapter 5 Using the SCXI 1125 Table 5 5 NI DAQmx Properties Property Short Name Description Analog Input General Properties AI Max Specifies the upper limit of the Advanced Range High input range Analog Input General Properties AI Min Specifies the lower limit of the Advanced Range Low input range Analog Input General Properties AI Gain Specifies a gain factor to apply to Advanced Gain and Offset the signal conditioning portion Gain Value of the channel Analog Input Measurement Type AI MeasType Indicates the measurement to take with the analog input channel ay Note This is not a complete list of NI DAQmx properties and does not include every property you may need to configure your application For a complete list of NI DAQmx properties and more information on NI DAQmx properties refer to your ADE help file Developing Your Application in Traditional NI DAQ Legacy ny Note If you are not using an
35. ain configuration 3 1 4 1 ground referenced signal connections AC coupled signal connection figure 2 4 description 2 2 H high voltage measurements 5 4 SCXI 1125 User Manual input characteristics A 1 installation connecting SCXI 1125 to DAQ device for parallel scanning 1 5 connecting to DAQ device for multiplexed scanning in PXI combination chassis 1 4 3 2 in SCXI chassis 1 4 3 2 into SCXI chassis 1 4 removing SCXI 1125 from Measurement amp Automation Explorer C 1 from SCX chassis C 1 L LabVIEW multiplexed scanning operations SCXI channel string 5 25 virtual channel string 5 26 parallel scanning operations 5 28 low level DAQ functions in multiplexed scanning 5 28 maximum working voltage A 8 Measurement amp Automation Explorer removing SCXI 1125 C 1 self test verification troubleshooting 1 7 multiplexed mode operating in 4 2 performing scans 5 27 C and low level DAQ functions 5 28 rear signal connector pin assignments figure 2 8 table 2 8 ni com theory of multiplexed hardware operation 4 3 using software for scanning operations LabVIEW and SCXI channel string 5 25 LabVIEW and virtual channel string 5 26 multiplexed mode operation connecting to SCXI 1125 for DAQ device in PXI combination 1 4 3 2 in SCXI chassis 1 4 3 2 NI DAQ version required D 2 P parallel mode connecting SCXI 1125 to DAQ device 1 5 theory of parallel hardware operation 4 4 using sof
36. ain Range 1 5V 2 2 5 V 5 1V 10 0 5 V 20 0 25 V 50 0 125 V 100 0 05 V 200 0 025 V 250 0 020 V 500 0 010 V 5 31 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 SCXI 1125 User Manual Table 5 9 Gain Values and Input Limits Continued Gain Range 1000 0 005 V 2000 0 0025 V If you are using a C based ADE use the following procedure to do an offset calibration on the SCXI 1125 1 Make sure the DAQ device or DMM you are using has a valid calibration and meets the accuracy specifications for your application 2 Use the NI DAQ function SCXI_Calibrate to calibrate one channel of the SCXI 1125 a e f Enter the DAQ device DAQ channel module slot and module channel for the channel you want to calibrate Select internal calibration 0 as the operation you are going to perform Select the load area 1 as the EEPROM area you want to update Since offset varies with gain enter the gain setting for which you are calibrating offset Enter 1 for the terminal block gain since it is not used Enter 0 0 as the input reference voltage 3 Repeat step 2 for calibrating additional channels The SCXI 1125 may take a few seconds to perform the calibration After completion your module will have new calibration constants stored for the channels and gains you calibrated Two Point Gain and Offset Calibration If you also need to calibrate the gain constants on the SCXI 1125 you m
37. alog bus where SCX analog signals are routed A serial clock signal used to synchronize digital data transfers over the SER DAT IN and SER DAT OUT lines serial data input signal serial data out to cabled DAQ device A device that responds to a physical stimulus heat light sound pressure motion flow and so on and produces a corresponding electrical signal Primary characteristics of sensors are sensitivity frequency range and linearity The time required for an amplifier relays or other circuits to reach a stable mode of operation See autozero The method of calibrating the gain of strain gauge data acquisition channel by placing a resistor of known value in parallel with a bridge element The manipulation of signals to prepare them for digitizing The first slot in a VXI or SCXI system The relative deformation of an object subjected to stress Hence strain is dimensionless synchronization pulse for scanning A measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded SCXI 1125 User Manual Glossary T thermocouple typ U UL VDC VI virtual channels voltage excitation Vins W working isolation working voltage SCXI 1125 User Manual A temperature sensor created by joining two dissimilar metals The junction produces a small voltage as a function of the temperature typical Underwriters Laboratory volts volts direct curr
38. an be entered in any order or repeated in the channel string Performing a Multiplexed Scan To perform a multiplexed scan in your application perform the following steps 1 Open an analog input example in your ADE 2 Enter the appropriate SCXI channel string or virtual channel string into the channels parameter 3 Either enter the input limits for signals connected to the module to adjust the gain settings in your system or use the default gain settings from the configuration utility and then run the application When using virtual channels the default input limits configured in the virtual channel configurator are used You have completed a multiplexed scan using your SCXI 1125 This is not a comprehensive discussion of SCXI scanning using LabVIEW or Measurement Studio but it should give you enough information to help you get started with the examples that are shipped with these software packages National Instruments Corporation 5 27 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 C and Low Level DAQ Functions When using a C based environment several steps are needed to configure the SCXI 1125 for multiplexed scanning The following procedure outlines the steps for programming with the low level DAQ function calls 1 Prepare the SCXI 1125 settings by either loading the original SCXI configuration settings using SCXI_Load_Config or by specifying the gain and filter settings using SCXI_Set_Gain and SCXI_Confi
39. are depends on the ADE you are using While using LabVIEW or Visual Basic all scanning operations are prepared in software by using an SCXI channel string as the input to the channel parameter in the analog input VI or function These ADEs also 5 24 ni com Chapter 5 Using the SCXI 1125 support virtual channels using Data Neighborhood DAQ Channel Wizard in MAX In LabWindows CVI C or C development environments several NI DAQ function calls need to be made to set up each module involved in the scan the chassis and the E Series DAQ device controlling the scan In Measurement Studio SCXI channels must be configured as virtual channels tags in MAX A discussion describing how to implement multiplexed scanning in the different ADEs follows Refer to your ADE manual and the DAQ analog input examples that come with your application software for more detailed information on programming the SCXI modules for scanning in multiplexed mode LabVIEW and the SCXI Channel String For LabVIEW and Visual Basic the channel string determines the sequence in which SCXI channels are scanned In LabVIEW an array of these channel strings configures multiple modules in the scan list When the application program runs the channel string is used for programming the channel information into the SCXI system The format of the channel string is as follows obx scy mdz channels where e obx is the onboard E Series DAQ device channel with
40. arted Guide and the SCXI Quick Start Guide for more information on installing and configuring your hardware You also can use the DAQ Assistant to graphically configure common measurement tasks channels or scales SCXI 1125 User Manual 3 2 ni com NI DAQmx Chapter 3 Configuring and Testing In NI DAQmx you can configure software settings such as filter bandwidth and gain input signal range in the following ways Task or global channel in MAX Functions in your application 3 Note All software configurable settings are not configurable both ways This section only discusses settings in MAX Refer to Chapter 4 Theory of Operation for information on using functions in your application These sections describe settings that you can change in MAX and where they are located Filter bandwidth configure the Device tab using either NI DAQmx Task or NI DAQmx Global Channel You also can set the value through your application Input signal range configure the input signal range using either NI DA Qmx Task or NI DAQmx Global Channel When you set the minimum and maximum range of NI DAQm x Task or NI DAQmx Global Channel the driver selects the best gain for the measurement You also can set it through your application Modes of operation configure only using chassis installation in software Refer to Chapter 1 About the SCXI 1125 for more information on chassis installation The default setting in NI DAQmx is multiplexed Term
41. ation settings are automatically passed from MAX LabVIEW can also set the SCXI 1125 configuration parameter operating mode to parallel or multiplexed programmatically by using the Set SCXI Information VI In Measurement Studio set the operating mode using MAX as described in Chapter 1 About the SCXI 1125 5 28 ni com Chapter 5 Using the SCXI 1125 After parallel mode has been configured in software you can scan the SCXI 1125 channels by entering the corresponding E Series DAQ device channels or a sequential SCXI channel string in the channel parameter in the analog input application You can also enter virtual channels however in parallel mode virtual channels containing CJC are disabled in MAX C and Parallel Mode When using a C based ADE you need no special steps for configuring the chassis the SCXI 1125 or the E Series DAQ device for parallel scanning You still have to configure the gain and filter settings by using SCXI_Set_Gain and SCXI_Configure_Filter You can use any of the E Series DAQ device analog input functions to get the data from the eight channels of the SCXI module After scanning convert the binary data to voltage data by using SCXI_Scale Refer to the NI DAQ User Manual for additional information on parallel scanning of SCXI modules Other Application Documentation and Material Refer to the ADE manual and the DAQ analog input examples that come with your application software for more detailed information
42. ature range which gives a preliminary accuracy of 0 04 C 1 73 uV divided by 41 0 uV C Next consider the accuracy of the cold junction sensor you are using For example using the SCXI 1328 which at about room temperature with little temperature gradient has an accuracy of 0 5 C You must convert this temperature accuracy back to a voltage corresponding to a K type thermocouple accuracy at 25 C This conversion produces about 20 uV of error Add the two voltages and determine the overall temperature error For example the total error due to the SCXI portion of the system in this example now becomes 21 73 uV This total error corresponds to about 0 53 C 21 73 uV divided by 41 0 uV C temperature error using the K type thermocouple at this range Determine the contribution of DAQ device error For example if using a 12 bit DAQ device the DAQ device contributes a gain of 2 and therefore the code width becomes 2 44 uV As a result the total system error now becomes 21 73 uV 2 44 uV which corresponds to about 0 59 C If you were to choose a 16 bit board you can achieve a code width of 0 153 uV producing a total system error of 0 53 C 5 3 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Making High Voltage Measurements SCXI 1125 User Manual Another common use of the SCXI 1125 is to make measurements up to 1000 VDC Making measurements beyond 5 V requires use of the an attenuator termi
43. ble D 1 Comparison of the SCXI 1125 with the SCXI 1120 we D 1 Table D 2 Digital Signals on the SCXI 1125 ssesssesseeseeesersrssrsreeresrsrrsrsresresrse D 3 National Instruments Corporation ix SCXI 1125 User Manual About the SCXI 1125 This chapter introduces the SCXI 1125 module and explains how to install the software and hardware The SCXI 1125 is an eight channel isolated analog input conditioning module with programmable gain and filter settings on each channel and is jumperless Each channel has 12 programmable gain settings from 1 to 2000 and two programmable filter settings of either 4 Hz or 10 kHz Each channel has an external circuit for grounding the inputs that you can use for offset calibration An onboard EEPROM provides nonvolatile storage of software correction constants for both gain and offset The SCXI 1125 provides up to 300 V ms working isolation per channel and has an input range of up to 1000 VDC when using an appropriate attenuator terminal block The SCXI 1125 supports both multiplexed and parallel output modes and includes a cold junction compensation CJC channel that you can scan in multiplexed mode What You Need to Get Started To set up and use the SCXI 1125 module you need the following Q Hardware SCXI 1125 module One of the following terminal blocks e SCXI 1305 e SCXI 1313A e SCXI 1320 e SCXI 1327 e S CXI 1328 e SCXI 1338 e TBX 1316 e TBX 1328 e TBX 1329 Na
44. connectors 3 Notes Refer to the Read Me First Safety and Radio Frequency Interference document before removing equipment covers or connecting or disconnecting any signal wires For EMC compliance operate this device with shielded cabling The isolated channels of the SCXI 1125 allow you to make precision high voltage measurements or low voltage measurement of signals riding on high common mode voltages while protecting sensitive computer parts and equipment connected to the module The isolated amplifiers fulfill two purposes on the SCXI 1125 module First they can convert a small signal riding on a high common mode voltage into a single ended signal with respect to the SCXI 1125 chassis ground With this conversion you can extract the analog input signal from a high common mode voltage before sampling by the E M Series DAQ device Second the isolation amplifier amplifies and filters an input signal resulting in increased measurement resolution and accuracy The following sections explain how to make signal connections to maximize the effectiveness of the SCXI 1125 for conditioning analog signals AC and DC Voltage Connections You can make input signal connections to the SCXI 1125 through the front signal connector or through accessory terminal blocks Chapter 1 About the SCXI 1125 contains a list of SCXI 1125 compatible terminal blocks Terminal blocks have features such as screw terminal connectivity BNC connectivity cold junctio
45. ct for any additional regulatory compliance information To obtain the DoC for this product visit ni com certification search by model number or product line and click the appropriate link in the Certification column National Instruments Corporation A 9 SCXI 1125 User Manual Appendix A Specifications Environmental Management Ix National Instruments is committed to designing and manufacturing products in an environmentally responsible manner NI recognizes that eliminating certain hazardous substances from our products is beneficial not only to the environment but also to NI customers For additional environmental information refer to the NMI and the Environment Web page at ni com environment This page contains the environmental regulations and directives with which NI complies as well as any other environmental information not included in this document Waste Electrical and Electronic Equipment WEEE EU Customers At the end of their life cycle all products must be sent to a WEEE recycling center For more information about WEFE recycling centers and National Instruments WEEE initiatives visit ni com environment weee htm EFAA minke l BEDE HE RoHS RAZA National Instruments 6 t E ETIR EAr P ENEN A ERS ROHS KF National Instruments FE RoHS ALEIS EA WK ni com environment rohs_china For information about China ROHS compliance go to ni com environment rohs_china S
46. d devices in MAX Removing the SCXI 1125 from a Chassis Consult the documentation for the chassis and accessories for additional instructions and precautions To remove the SCXI 1125 module from an chassis complete the following steps while referring to Figure C 1 1 Power off the chassis Do not remove the SCXI 1125 module from a chassis that is powered on National Instruments Corporation C 1 SCXI 1125 User Manual Appendix C Removing the SCXI 1125 If the SCXI 1125 is the module cabled to the E Series DAQ device disconnect the cable Remove any terminal block that connects to the SCXI 1125 Rotate the thumbscrews that secure the SCXI 1125 to the chassis counterclockwise until they are loose but do not completely remove the thumbscrews Remove the SCXI 1125 by pulling steadily on both thumbscrews until the module slides completely out Cable SCXI Module Thumbscrews SCXI 1125 Sensor RON 5 Terminal Block 6 SCXI Chassis Power Switch 7 SCXI Chassis SCXI 1125 User Manual Figure C 1 Removing the SCXI 1125 C 2 ni com Common Questions This appendix lists common questions related to the use of the SCXI 1125 The SCXI 1125 is backward compatible with the SCXI 1120 but what are the major differences between the SCXI 1120 and the SCXI 1125 Table D 1 compares the major specifications and features of the two modules Other specifications and features of the SCXI 1125 are the same
47. e 5 1 assumes all properties are configured before the task is started Table 5 3 NI DAQmx Properties Property Short Name Description Analog Input General Properties AI Max Specifies the upper limit of the Advanced Range High input range Analog Input General Properties AI Min Specifies the lower limit of the Advanced Range Low input range Analog Input General Properties AI Lowpass CutoffFreq Specifies in hertz the Filter Analog Lowpass Cutoff frequency corresponding to the Frequency 3 dB cutoff of the filter You can specify 4 0 or 10000 3 Note This is not a complete list of NI DAQmx properties and does not include every property you may need to configure your application It is a representative sample of important properties to configure for measurements For a complete list of NI DAQmx properties and more information about NI DAQm x properties refer to your ADE help file SCXI 1125 User Manual 5 8 ni com Chapter 5 Using the SCXI 1125 Acquiring Analyzing and Presenting After configuring the task and channels you can start the acquisition read measurements analyze the data returned and display it according to the needs of your application Typical methods of analysis include digital filtering averaging data performing harmonic analysis applying a custom scale or adjusting measurements mathematically NI provides powerful analysis toolsets for each NI ADE to help y
48. e temperature ee eee 20 to 70 C Humidity erson erneten 10 to 90 RH noncondensing Maximum altitude cccecccesssseeeees 2 000 meters Pollution Degree indoor use only 2 A 8 ni com Appendix A Specifications Safety This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement control and laboratory use e IEC 61010 1 EN 61010 1 e UL61010 1 CSA 61010 1 ay Note For UL and other safety certifications refer to the product label or visit ni com certification search by model number or product line and click the appropriate link in the Certification column Electromagnetic Compatibility This product is designed to meet the requirements of the following standards of EMC for electrical equipment for measurement control and laboratory use e EN 61326 EMC requirements Minimum Immunity e EN 55011 Emissions Group 1 Class A e CE C Tick ICES and FCC Part 15 Emissions Class A 3 Notes For EMC compliance operate this device according to product documentation For EMC compliance operate this device with shielded cabling CE Compliance This product meets the essential requirements of applicable European Directives as amended for CE marking as follows e 2006 95 EC Low Voltage Directive safety e 2004 108 EC Electromagnetic Compatibility Directive EMC 3 Note Refer to the Declaration of Conformity DoC for this produ
49. ed to the E M Series DAQ device the module sends its signals through the SCXIbus to the cabled module The cabled module whose routing is controlled by the SCXI chassis routes the SCXIbus signals to the E M Series DAQ device through the CHO signal on the rear signal connector If the E M Series DAQ device scans the cabled module the module routes its input signals through the CHO signal on the rear signal connector The power of SCXI multiplexed scanning is its ability to route many input channels to a single channel on the E M Series DAQ device ay Note The SCXI 1125 parallel outputs continuously drive the rear signal connector output pins even when you configure the module in multiplexed mode If the module is cabled to an E M Series DAQ device in multiplexed mode the differential inputs 1 through 7 on the E M Series DAQ device cannot be used for general purpose analog input Refer to Appendix D Common Questions for more information on available pins on the rear signal connector Multiplexed mode is typically used for performing scanning operations with the SCXI 1125 Immediately prior to a multiplexed scanning operation the SCXI chassis is programmed with a module scan list that controls which module sends its output to the SCXIbus during a scan You can specify this list to scan the modules in the chassis in any order with an arbitrary number of channels for each module entry in the list You can randomly scan the channels on the SCXI 1125
50. eeeeseseeeeseesees 5 5 Typical Program Flowchart 00 eee eeeeseeseceeeeseeeeeeseesseeseessecseeesesseenseeeenaes 5 5 General Discussion of Typical Flowchart eee eeeecseeeseeseeeeeseeeseeeees 5 7 Creating a Task Using DAQ Assistant or Programmatically 5 7 Adjusting Timing and Triggering oo eee cece eeeeeeceeeeeeeeeeeees 5 7 SCXI 1125 User Manual vi ni com Contents Configuring Channel Properties cece eeeeseeseceseeseeeeeeeeneeeseenees 5 8 Acquiring Analyzing and Presenting 0 0 0 0 eee eeeeseeeeeeseeeeeenees 5 9 Completing the Application 0 0 cece eseeseeeceseeseeneeeseseeeeaeenees 5 9 Developing an Application Using LabVIEW eee ceeeseeseeeeeeeneeeseenees 5 9 Using a DAQmx Channel Property Node in LabVIEW 0 00 5 11 Specifying Channel Strings in NI DAQMX eee ceeeteeeeeeetneeeseeseeeaeens 5 12 Text Based ADES niren rne asses aialisien abel aed actos 5 14 Measurement Studio Visual Basic NET and C ccccccesesseessteeeeneeeees 5 14 Programmable NI DAQmx Properties ccceceseeseeseeeeseeeetsees 5 14 Developing Your Application in Traditional NI DAQ Legacy eee eeeeeeeeeees 5 15 Traditional NI DAQ Legacy in LabVIEW cc ceceesceescseeneceneeeseeeeneeeneeesaee 5 16 Typical Program Plow sissioni isnot paoia 5 17 Configure the SCXI 1125 Settings Using Traditional NI DAQ Legacy tn Lab VIEW c sicceledescetsschescaisaticenseshcgassushsbepeveesedssicaasseeeaz
51. ent virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument 2 a LabVIEW software module VI which consists of a front panel user interface and a block diagram program Channel names that can be defined outside of the application and used without having to perform scaling operations Virtual channels are called custom channels in MAX 3 0 and later A source that supplies the voltage needed by a sensor for its proper operation volts root mean square A level of protection pertaining to a working voltage The highest voltage that should be applied to a product in normal use normally well under the breakdown voltage for safety margin G 10 ni com Index A AC and DC voltage connections 2 1 AC coupling 2 4 floating AC coupled signal connection figure 2 4 floating signal 2 3 floating signal connection figure 2 3 front signal connector figure 2 6 table 2 6 ground referenced AC coupled signal connection figure 2 4 ground referenced signal 2 2 ground referenced signal connection figure 2 2 analog input channels on DAQ device D 2 C C language multiplexed scanning operations 5 27 parallel scanning operations 5 28 scanning channels D 4 calibration gain values and input limits table 5 31 one point offset calibration 5 31 overview 5 30 two point gain and offset calibration 5 32 chan
52. essisestes 5 18 Configure Start Acquisition and Take Readings Using Traditional NI DAQ Legacy in LabVIEW 0 0 cece eseeseceeeseeseeeaeceseesecneeeaeeseeeaeesees 5 19 Convert Scaling Using Traditional NI DAQ Legacy in LabVIEW 5 20 Analyze and Display Using Traditional NI DAQ Legacy in LabVIEW 5 20 Traditional NI DAQ Legacy in Text Based ADES ccceesceeseeeeneeeeeeeeees 5 21 Configuring System Settings Using Traditional NI DAQ Legacy C API 5 21 Configure Module Settings Using Traditional NI DAQ Legacy C API 5 22 Perform Offset Null Compensation Using Traditional NI DAQ Legacy C API eee eee ceeecseeeeeseeeeeeaees 5 23 Perform Acquisition Using Traditional NI DAQ Legacy C API 5 23 Perform Scaling Analysis and Display cece eececeeseeeeeeeeeeeeeeeeseteeeeaees 5 24 Using Software for Multiplexed Scanning eee ee eeeeseceeceeeeeeeeseeeeeeaees 5 24 LabVIEW and the SCXI Channel String 00 eee eeeeeeeeees 5 25 LabVIEW and the Virtual Channel String eects 5 26 Performing a Multiplexed Scan eee ceeeseesceeseeseceseeeeesecsesesesseseaeseeeeaee 5 27 C and Low Level DAQ Functions ccccceeesscesseeeeeseesssneeeseeeens 5 28 Using Software for Parallel Scanning 0 0 0 eee ee eeeeeeseeeseceeeeeeeeeeeseseeeeaees 5 28 LabVIEW and Parallel Mode eee eee eeeeeseeseeeeceseeseeesesseensetsees 5 28 Cand Parallel Mode sneen nedenin ania 5 29 Other Application Documentation and Material 20 0 0
53. etecting modules for the first time configuration of the chassis Installing SCXI Using Traditional NI DAQ Legacy in Software Refer to the SCXT Quick Start Guide for information on installing modules using Traditional NI DAQ Legacy in software Manually Adding Modules in Traditional NI DAQ Legacy If you did not auto detect the SCXI modules you must manually add each of the modules Refer to the SCXI Quick Start Guide to manually add modules ay Note NI recommends auto detecting modules for the first time configuration of the chassis Verifying and Self Testing the Installation The verification procedure for the SCXI chassis is the same for both NI DAQmx and Traditional NI DAQ Legacy To test the successful installation for the SCXI chassis refer to the SCXT Quick Start Guide Verify that the chassis is powered on and correctly connected to an E M Series DAQ device 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 SCXI 1125 User Manual 1 6 ni com Chapter 1 About the SCXI 1125 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 Troubleshooting in NI DAQmx If you get a Verify SCXI Chassis message bo
54. evice you connect to the module SCXI 1125 User Manual 4 4 ni com Using the SCXI 1125 This chapter discusses typical applications for the SCXI 1125 While this list is not comprehensive it provides some guidance on how to improve measurement accuracy for some of the most popular applications of the SCXI 1125 Advanced operations such as calibration and using the CJC channel are discussed as well Temperature Measurements Using Thermocouples Making isolated temperature measurements from thermocouples is a common use of the SCXI 1125 This section discusses how to use thermocouples CJC and how to calculate the temperature accuracy of the SCXI 1125 NI recommends using the SCXI 1328 terminal block to make thermocouple measurements with the SCXI 1125 Although you can use many of the SCXI terminal blocks for thermocouple measurements the SCXI 1328 has an isothermal design that reduces temperature gradients within the terminal block housing This design reduces the CJC errors which might reduce the accuracy of your temperature measurement Most SCXI terminal blocks available for the SCXI 1125 contain a cold junction temperature sensor which is used for measuring ambient temperature This sensor connects to a special channel on the SCXI 1125 inside the terminal block close to where the thermocouple connects to the screw terminals 3 Note Place the SCXI chassis away from extreme temperature gradients to minimize the temperature gradie
55. fer to the SCXT Quick Start Guide to install your SCXI 1125 module Connecting the SCXI 1125 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCX Quick Start Guide to install the cable adapter and connect the SCXI modules to the DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1125 module s Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M Series DAQ Device for Multiplexed Scanning Refer to the SCXI Quick Start Guide to connect the SCXI modules to the DAQ device If you have already installed the appropriate software refer to Chapter 3 Configuring and Testing to configure the SCXI 1125 module s SCXI 1125 User Manual 1 4 ni com Chapter 1 About the SCXI 1125 Connecting the SCXI 1125 to a n E M Series DAQ Device for Parallel Scanning This configuration allows you to route all eight channels of the SCXI 1125 in parallel to eight input channels of the E M Series DAQ device to which it is connected In this mode you cannot directly access the CJC channel Use this mode if you require a higher scanning rate than an SCX system in multiplexed mode allows If you have not already installed all the modules refer to the Installing the SCXI 1125 Module into the SCXI Chassis section then complete the following steps 1 Power off the SCXI chassis and the computer that contains the E M Serie
56. gure_Filter 2 Use SCXI_SCAN_Setup to specify the module scan list the start channel of each module and the number of channels to scan on each module SCXI_SCAN_Setup accepts an array of start channels and an array of the number of channels to scan in each module It is not possible to repeat channels or use nonsequential channels using SCXI_SCAN_Setup 3 Next use SCXI_MuxCtr_Setup to program the E Series DAQ device with the correct number of channels multiplexed per scan This number must match the total number of channels programmed in step 2 You are now ready to acquire the channel data with the E Series DAQ device If you are using a multifunction E Series DAQ device you can use SCAN_OP to perform the scanning operation After scanning convert the binary data to voltage data using SCXI_Scale Refer to the NI DAQ User Manual for additional information on scanning with DAQ devices Using Software for Parallel Scanning SCXI 1125 User Manual Performing scanning operations in parallel mode requires no special channel strings or function calls for setting up channel sequencing as is required in multiplexed mode Scanning the SCXI 1125 channels on a differentially configured DAQ device is done as if there were no SCXI 1125 module connected The only requirement is that you must configure the module for parallel mode in MAX as described in Chapter 1 About the SCXI 1125 LabVIEW and Parallel Mode In LabVIEW the SCXI 1125 configur
57. hapter 2 Connecting Signals AC and DC Voltage Connections 0 ccc eseeceseeseeesececeesecseeeseesecesecaeensecseenseeaeenaes 2 1 Ground Referenced Signal cece cece eseeesesseceseeseeesecsecesecseenseesesenesseeeaeenees 2 2 Floats Sienalainen EE E EAE E EE EEE AEE 2 3 C Cou pN ia eles a E E A ae an eee ies 2 4 Pin ASSISTIMeENtS orero ea e EE E ete ee TO RE alae 2 5 Temperature Sensor Connection s eeesseessersseesseerssestesrsreersrestrsrsresrsresreseet 2 7 Rear Signal Connector onenera e e E aE E E E EE EERS EEA EEES 2 7 National Instruments Corporation v SCXI 1125 User Manual Contents Chapter 3 Configuring and Testing SCXI 1125 Software Configurable Settings 0 0 elec ceceseeseeeeeseeeesetseeeseeeeeseeaeees 3 1 Common Software Configurable Settings cee ec eeeeeeseeceseeseeeeeseeeeeeeees 3 1 Filter Bamd widths c seccsdecdesiscesescasestusdstasssvadecds setedssenaseessnastvsssbsadeee s 3 1 Gain Input Range 2cie sins cies e pi e ai E 3 1 Connecting the SCXI 1125 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning 3 2 Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M Series DAQ Device for Multiplexed Scanning 3 2 Configurable Settings in MAX sccsniininniini aaa 3 2 INIEDA QUn xX ni iva het nee test sno evs aden PA TE A E Aa 3 3 Creating a Voltage Global Channel or Task 3 3 Traditional NI DAQ Legacy iieiaeie iia ea iA 3 4 Configuring Module Prope
58. he signals on pins A6 A8 C6 and C8 are reserved for serial communication The 5 V signal and CHS GND signals are used as the power supply and ground signals for the CJC sensor and other circuitry on the terminal block The pin assignments for the SCXI 1125 front signal connection are shown in Table 2 1 UN Caution Do not make signal connections to pins A2 A4 A6 A8 C2 C4 C6 or C8 on the front signal connector Connecting external signals to these pins can damage the SCXI 1125 Module National Instruments Corporation 2 5 SCXI 1125 User Manual Chapter 2 Connecting Signals Table 2 1 Front Signal Pin Assignments Front Connector Diagram Pin Number Column A Column B Column C 32 AIO AIO Column 31 Z A 2 c 30 AIl AIl 32 o o 29 28 NC NC 30 o o 29 27 E _ 28 o o 26 AI2 AI2 27 25 eo o 24 AI3 m AI3 25 24 o o 2 E 23 22 NC a NC 22 o 21 21 20 AI4 AI4 20 o o 19 19 ig 6 18 AI5 AI5 17 17 16 9 16 NC NC 15 15 14 o o 13 14 AI6 AI6 12 o o 13 11 12 AI7 AI7 10 o o 11 _ 9 10 NC NC 8 o 7 9 6 o o 8 RSVD RSVD 5 7 7 7 7 4 o o 3 6 RSVD RSVD 2 o 5 a 1 4 5 V CJ TEMP P 3 NC means no connection 2 CHS
59. his voltage to a temperature 2 Convert this temperature to the corresponding voltage for the thermocouple type in use Read the input voltage from the thermocouple 4 Add the two voltages Translate the resultant voltage into the thermocouple temperature reading You have completed the steps to get the true temperature reading from the thermocouple junction National Instruments software ADEs have useful conversion functions for CJC In LabVIEW virtual channels with the CJC channel invoked or the Convert Thermocouple Reading VI are used In C use the NI DAQ function Thermocouple_Convert In C you might also need to use the function Thermistor_Convert if your terminal block uses a thermistor to perform CJC For more information about CJC refer to your software ADE user documentation To calculate the temperature accuracy of your SCXI 1125 you must consider several factors First the type of sensor and the temperature range you expect directly affects which gain your SCXI 1125 module uses for voltage readings thereby directly affecting the resolution with which you can read temperature After determining the range necessary for your application you can apply the measurement accuracy specifications of the SCXI 1125 such as offset error gain error and noise to determine how these will affect your temperature measurement Next you must consider the accuracy of your cold junction sensor and incorporate this into the total tempe
60. inal block attenuation for terminal blocks with manually adjustable attenuation such as the SCXI 1327 you must configure the attenuator in the chassis configurator Refer to the SCXT Quick Start Guide for more information 3 Note Refer to Chapter 4 Theory of Operation for information on configuring the settings for your application using Traditional NI DAQ Legacy Creating a Voltage Global Channel or Task To create anew NI DAQm x global task or channel complete the following steps 1 Double click Measurement amp Automation on the desktop 2 Right click Data Neighborhood and select Create New 3 Select NI DAQmx Task or NI DAQmx Global Channel and click National Instruments Corporation Next 3 3 SCXI 1125 User Manual Chapter 3 Configuring and Testing 4 Select Analog Input 5 Select Voltage 6 Ifyou are creating a task you can select a range of channels by holding down the lt Shift gt key while selecting the channels You can select multiple individual channels by holding down the lt Ctrl gt key while selecting channels If you are creating a channel you can only select one channel Click Next 7 Name the task or channel and click Finish 8 In the box labelled Channel List select the channel s you want to configure You can select a range of channels by holding down the lt Shift gt key while selecting the channels You can select multiple individual channels by holding down the lt Ctrl gt ke
61. ine motors generators transformers fluorescent lights soldering irons CRT displays computers electrical storms welders and radio transmitters and internal sources such as digital clocks microprocessors and switched mode power supplies Video system noise can take various forms including snow which is a random video noise It corrupts signals you are trying to send or receive A constant error added to a measurement along the whole transfer curve For example in mx b the offset error is b The provision in strain gauge signal conditioning hardware to remove the unwanted offset voltage present at the output of a strain gauge bridge when no strain is applied A type of SCXI operating mode in which the module sends each of its output channels directly to a separate analog input channel of the DAQ device connected to the module The range of input frequencies that are passed to the filter output without attenuation SCXI 1125 User Manual Glossary ppm PXI R resolution RMA rms RSVD RTI S S sample sample rate scan SCANCLK SCXI 1125 User Manual parts per million A rugged open system for modular instrumentation based on CompactPCI with special mechanical electrical and software features The PXIbus standard was originally developed by National Instruments in 1997 and is now managed by the PXIbus Systems Alliance The smallest signal increment that can be detected by a measurement sys
62. ing the SCXI 1125 Table 5 4 Programming a Task in LabVIEW Flowchart Step VI or Program Step Create Task in DAQ Assistant Create a Task Programmatically optional Create aDAQmx Task Name Constant located on the Controls Modern I O DAQmx Name Controls subpalette right click it and select New NI DAQmxTask MAX DAQmx Create Task vi tThis VI is optional if you created and configured your task using the DAQ Assistant However if you use it in Lab VIEW any changes you make to the task will not be saved to a task in MAX Create AI Channel optional DAQmx Create Virtual Channel vi AI Voltage by default to change to a channel click AI Voltage and select the type of analog input you want This VI is optional if you created and configured your task and channels using the DAQ Assistant Any channels created with this VI are not saved in the DAQ Assistant They are only available for the present session of the task in LabVIEW Adjust Timing Settings optional DAQmx Timing vi Sample Clock by default This VI is optional if you created and configured your task using the DAQ Assistant Any timing settings modified with this VI are not saved in the DAQ Assistant They are only available for the present session Configure Channels optional DAQmx Channel Property Node refer to the Using a DAQmx Channel Property Node in LabVIEW section for more information This step is optional if you created a
63. ise that can ride on the floating signal If the floating signal is not configured like Figure 2 2 the noise can couple to the chassis ground through the amplifier and exhibit a differential mode signal that can be amplified by the amplifier Connecting the signal to chassis ground breaks the isolation barrier Figure 2 2 Connecting a Floating Signal National Instruments Corporation 2 3 SCXI 1125 User Manual Chapter 2 Connecting Signals AC Coupling You can have an application where you wish to measure only AC voltages and remove the DC component of a signal before amplification and sampling In such cases you can connect a capacitor in series with one or both input terminals of the SCXI 1125 as shown in Figures 2 3 and 2 4 A resistor is connected across the input terminals of the channel to DC reference the input stage of the SCXI 1125 You do not need to use a bias resistor with any high voltage terminal blocks since the terminal blocks already have a resistor between the input terminals or with the SCXI 1305 BNC connectivity terminal block since this terminal block already has an AC coupling option built in a ae gt gt i YT Module Figure 2 3 Connecting a Floating AC Coupled Signal UN Caution Connecting a signal source to chassis ground in Figures 2 2 and 2 3 breaks the isolation barrier SCXI 1125 User Manual 4 7 fete eee ee ee ees
64. isition operation SCAN_Op does not return until Traditional NI DAQ Legacy acquires all the data or an acquisition error occurs MIO AI and DSA devices only For this reason it is sometimes useful to use SCAN_Op in conjunction with the function Timeout_Config which establishes a timeout limit synchronous functions to ensure that these functions eventually return control to your application After acquiring data using SCAN_Op the resultant data is not organized by channel so you should demultiplex the data using SCAN_Demux SCAN_Demux rearranges or demultiplexes data acquired by a SCAN_Op into row major order meaning each row of the array holding National Instruments Corporation 5 23 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 the data corresponds to a scanned channel for easier access by C applications BASIC applications need not call SCAN_Demux to rearrange two dimensional arrays since these arrays are accessed in column major order For more information regarding each acquisition function refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ Perform Scaling Analysis and Display 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 1125 has stored software calibration cons
65. l NC 35 36 AI HOLD COMP AI HOLD 47 48 49 50 SER CLK 37 38 NC NC 39 40 NC NC means no NC 41 42 NC connection NC 43 44 NC NC 45 46 SYNC NC 47 48 NC NC 49 50 NC SCXI 1125 User Manual 2 8 ni com Configuring and Testing This chapter discusses configuring the SCXI 1125 in MAX for use with either NI DAQm x or Traditional NI DAQ Legacy creating and testing a virtual channel global channel or task For more information on the relationship between the settings and the measurements and how to configure settings in your application refer to Chapter 4 Theory of Operation SCXI 1125 Software Configurable Settings This section describes the common software configurable settings and how to verify the signal using both NI DAQm x and Traditional NI DAQ Legacy Common Software Configurable Settings This section describes the most frequently used software configurable settings for the SCXI 1125 Refer to Chapter 4 Theory of Operation for a complete list of software configurable settings Filter Bandwidth Filter bandwidth is a software configurable setting that allows you to select a lowpass filter cutoff frequency You can choose 4 0 Hz or 10 kHz Gain Input Range Gain input range is a software configurable setting that allows you to choose the appropriate amplification to fully utilize the range of the E M Series DAQ device In most applications NI DAQ chooses and sets the gain for you determined by the input range
66. l Significant Possible Parameters Setting NI DAQ Function to Use Parameters Values Gain SCXI_Set_Gain f64 gain 1 2 5 10 20 50 100 gain setting 200 250 500 1000 2000 Bandwidth SCXI_Configure_Filter f64 freq 4 0 10 000 0 Hz filter cutoff frequency if filterMode 1 Perform Offset Null Compensation Using Traditional NI DAQ Legacy C API After configuring the system settings and module properties you can perform an offset null compensation programmatically using SCXI_Calibrate SCKI_Calibrate takes measurements and adjusts the coarse and fine offset null potentiometers to minimize or eliminate any electrical offset for a channel Repeat this process for each channel by calling the SCXI_Calibrate function in a loop Use the resulting imbalance in your application as a software correction factor by determining the residual voltage from the imbalance and subtracting this residual offset from each future measurement For more information regarding the operation of SCXI_Calibrate refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ Perform Acquisition Using Traditional NI DAQ Legacy C API There are several NI DAQ functions you can use to take measurements Usually in SCXI the preference is to take multiple samples from multiple channels using the SCAN_Op function SCAN_Op performs a synchronous multiple channel scanned data acqu
67. m milli 10 3 k kilo 103 M mega 10 G giga 10 T tera 10 Numbers Symbol 7 Degrees IV lA 5 V signal Greater than or equal to Less than or equal to Ohms Per Percent Plus or minus 5 VDC source signal National Instruments Corporation G 1 SCXI 1125 User Manual Glossary A A D absolute accuracy AC ADC ADE AI GND AI HOLD COMP AI HOLD amplification autozero bandwidth bias current bit BNC SCXI 1125 User Manual analog to digital The maximum difference between the measured value from a data acquisition device and the true voltage applied to the input typically specified as voltage alternating current analog to digital converter An electronic device often an integrated circuit that converts an analog voltage to a digital number application development environment A software environment incorporating the development debug and analysis tools for software development analog input ground clock that triggers scanning A type of signal conditioning that improves accuracy in the resulting digitized signal by increasing signal amplitude relative to noise A procedure for eliminating offsets generated by an amplifier stage The range of frequencies present in a signal or the range of frequencies to which a measuring device can respond The small input current flowing into or out of the input terminals of an amplifier one binary digit
68. mdz is the slot position where the module is located with z being the particular slot number The slots in a chassis are numbered from left to right starting with 1 National Instruments Corporation B 1 SCXI 1125 User Manual Appendix B Using SCX Channel Strings with Traditional NI DAQ Legacy 7 0 or Later channels is the list of channels that are scanned for module z It can have several formats obx scy mdz nx where nxis a single input channel obx scy mdz n0 n2 wheren0O n2are individual input channel that are not necessarily sequential obx scy mdz n0 n3 where n0 and n3 represent an ascending sequential list of input channels inclusive obx scy mdz n0 n2 n3 n4 n1 n5 n2 where n0 n2 and n5 represent single channels not necessarily sequential and n3 and n4 represent the endpoints of an ascending sequential list of channels inclusive In this case channels n1 and n2 are explicitly repeated in the channel list ik Notes Using parenthesis surrounding multiple channels in a channel string is important for correct scanning operation of the SCXI channels In a single chassis system the obx specifier is optional and causes the gains on the module and E M Series DAQ device to be automatically set to fit the input limits parameter When this specifier is omitted the default gain on the E M Series DAQ device usually the lowest gain is used but the SCXI 1125 gain is adjusted to fit the inpu
69. measurement accuracy kelvin A type of signal conditioning in which software linearizes the voltage levels from transducers so the voltages can be scaled to measure physical phenomena meters 1 Mega the standard metric prefix for 1 million or 10 when used with units of measure such as volts and hertz 2 mega the prefix for 1 048 576 or 22 when used with B to quantify data or computer memory multiplexed temperature sensor signal See also CJ TEMP Minimum 1 minutes 2 minimum multifunction I O To assign more than one signal to a channel G 6 ni com multiplexed mode mux NC NI DAQ noise 0 offset error offset null compensation P parallel mode passband National Instruments Corporation G 7 Glossary An SCXI operating mode in which analog input channels are multiplexed into one module output so that your cabled DAQ device has access to the module s multiplexed output as well as the outputs on all other multiplexed modules in the chassis through the SCXIbus multiplexer A switching device with multiple inputs that sequentially connects each of its inputs to its single output typically at high speeds in order to measure several signals with a single analog to digital converter not connected The driver software needed to use National Instruments DAQ devices and SCXI components Analog Unwanted signals Noise comes from both external sources such as the AC power l
70. mory When called the AI Start VI reads the configuration settings in the driver memory and then sends the actual control information to the SCXI 1125 module A setting established through 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 1125 settings shown in Table 5 6 Table 5 6 Settings for Configuring the SCXI 1125 Through the Al Parameter Allowable Settings AI Parameter VI Float In Boolean In or Value In Software Configurable Parameter Setting Name Value Data Type Values Filter Filter Setting 14 Float In dbl 4 0 10000 0 Bandwidth SCXI 1125 User Manual 5 18 ni com Chapter 5 Using the SCXI 1125 An example of using the AI Parameter VI to control an SCXI 1125 is shown in Figure 5 4 Allowable filter settings in Hz input limits 4 0 10000 0 ee device 1 H DELE ET f scri aeree APL Param Al channels 0 we 120 CO CS pocco xxeeery CD EEE beter c3 o j number of scans Fia Salting 77 1324 Lf code Tan Figure 5 4 Using the Al Parameter VI to Set Up the SCXI 1125 Configure Start Acquisition and Take Readings Using Traditional NI DAQ Legacy in LabVIEW After you have performed an offset null compensation and configured the SCXI 1125 settings for your application you can use the intermediate analog input functions AI Config VI AI Star
71. n temperature measurement and attenuation The pin assignment for the SCXI 1125 front signal connector is shown in Table 2 1 The positive input terminal for each channel is in Column A and the negative input terminal for each channel is in Column C Input connections to each channel are fully floating with respect to ground and National Instruments Corporation 2 1 SCXI 1125 User Manual Chapter 2 Connecting Signals completely isolated from other channels You can operate with common mode voltage levels up to 300 Vms Figures 2 1 through 2 4 show signal connection methods that give the highest noise immunity Ground Referenced Signal SCXI 1125 User Manual When the negative input signal line is connected either directly or indirectly to earth ground usually at the transducer end connect this line to the negative input terminal as shown in Figure 2 1 No ground connection is made at the SCXI 1125 This situation includes cases where a floating source can be riding on a high common mode voltage that is ground referenced Figure 2 1 Connecting a Ground Referenced Signal 2 2 ni com Chapter 2 Connecting Signals Floating Signal In cases where both signal lines at the transducer end are floating and no common mode voltage exists establish an earth connection at the SCXI 1125 by connecting the negative input line to chassis ground in the terminal block as shown in Figure 2 2 This eliminates no
72. n the needs of your application you choose one of these channel addressing methods to use in your LabVIEW application When you use virtual channels the maximum number of channels per E Series DAQ device is 512 in multichassis systems NI recommends using the virtual channel for ease of use Refer to Appendix B Using SCXI Channel Strings with Traditional NI DAQ Legacy 7 0 or Later for more information on how to create a virtual channel The SCXI channel string allows you to combine large numbers of channels into fewer scan list entries to measure the signal voltage level directly for custom scaling and to dynamically perform an offset null compensation in your application NI recommends using SCXI channel strings for more advanced applications In LabVIEW an array of these channel strings configures multiple modules for scanning When using SCXI channel strings you can scan up to 3 072 channels in a multichassis system using a single E Series DAQ device 3 Note You cannot mix virtual channels with the SCXI channel strings within the same channel string array SCXI 1125 User Manual To use virtual channels enter the name of a virtual channel into the analog input channel string If using multiple virtual channels enter them in a different index in the channel string array or separate them using a comma Since you can randomly scan analog input virtual channels you can enter the virtual channels you want to scan in any order or re
73. n use mt emp in place of cj temp obx scy mdz nl n2 n3 n4 n1 n5 n2 where n1 n2 and n5 represent single channels not necessarily sequential and n3 and n4 represent the endpoints of a sequential list of channels inclusive In this case channels n1 and n2 have explicitly been repeated in the channel list This random scanning format is not supported on all SCXI modules e obx scy mdz calgnd nI n2 where n1 and n2 represent a list of autozeroed channels inclusive In this case autozero channels cannot be scanned with input channels or the cold junction channel but must be scanned separately This feature is useful for measuring offsets that appear due to temperature drifts in the analog circuitry You can subtract these offsets from subsequent input readings to correct for temperature drift Refer to Appendix A Specifications for determining how temperature drift can affect your measurement accuracy 3 Note Repeating channels or having channels out of sequence in a scan list is not supported on all SCXI modules Please refer to the manual of each module for information on this feature SCXI 1125 User Manual LabVIEW and the Virtual Channel String For LabVIEW Measurement Studio and Visual Basic the channel string can also contain virtual channels For the SCXI 1125 these virtual channels are analog input channels you create that have custom names called tags in Measurement Studio that perform scaling linea
74. nal block The SCXI 1327 and SCXI 1313A terminal blocks have a selectable attenuator for choosing between no attenuation or 100 1 attenuation which allows you to use the SCXI 1125 with up to 300 Vims when using the SCXI 1327 and up to 150 Vms when using the SCXI 1313A The TBX 1316 has a fixed 200 1 attenuation which allows you to use the SCXI 1125 with up to 1000 VDC Measurement Category I The SCXI 1327 and SCXI 1313A also include a cold junction sensor so you can combine thermocouple measurements with high voltage measurements When making signal connections or when working with high voltage signals refer to the terminal block installation guide If you are using the SCXJ 1125 to measure signals with attenuation on the terminal block an external bias resistor is not needed because a bias resistor is already used for achieving the attenuation Table 5 1 lists the extended ranges of gain possible with the SCXI 1327 and SCXI 1313A Table 5 2 lists the extended gain possible with the TBX 1316 Table 5 1 Extended Gain and Range Using the SCXI 1327 or SCXI 1313A Overall Input SCXI 1125 SCXI 1327 SCXI 1313A Gain Range Gain Attenuation Attenuation 0 01 300 V 1 100 0 02 250 V 2 100 0 002 150 V 2 100 100 0 05 100 V 5 100 100 0 1 50 V 10 100 100 0 2 25 V 20 100 100 0 5 10 V 50 100 100 2 5 2V 250 100 100 5 4 ni com Chapter 5 Using the SCXI 1125 Table 5 2 Extended
75. nd fully configured the channels using the DAQ Assistant Any channel modifications made with a channel property node are not saved in the task in the DAQ Assistant They are only available for the present session Start Measurement DAQmx Start Task vi Read Measurement Analyze Data DAQmx Read vi Some examples of data analysis include filtering scaling harmonic analysis or level checking Some data analysis tools are located on the Functions Signal Analysis subpalette and on the Functions All Functions Analyze subpalette SCXI 1125 User Manual ni com Chapter 5 Using the SCXI 1125 Table 5 4 Programming a Task in LabVIEW Continued Flowchart Step VI or Program Step Display Data You can use graphical tools such as charts gauges and graphs to display your data Some display tools are located on the Controls All Controls Numeric Numeric Indicators subpalette and Controls All Controls Graph subpalette Continue Sampling For continuous sampling use a While Loop If you are using hardware timing you also need to set the DAQmx Timing vi sample mode to Continuous Samples To do this right click the terminal of the DAQmx Timing vi labeled sample mode and click Create Constant Click the box that appears and select Continuous Samples Stop Measurement DAQmx Stop Task vi This VI is optional clearing the task automatically stops the task Clear Task DAQmx
76. nel string calgnd channel string D 3 SCXI 5 25 virtual 5 26 channels C language scanning D 4 questions about D 3 unused analog input channels on DAQ device D 2 National Instruments Corporation common questions D 1 configuration troubleshooting self test verification 1 7 configuration settings filter bandwidth 3 1 4 2 gain 3 1 4 1 connecting SCXI 1125 to DAQ device See also DAQ devices for parallel scanning 1 5 connectors front signal connector pin assignments figure 2 6 table 2 6 rear signal connector description 2 7 pin assignments figure 2 8 table 2 8 conventions used in the manual iv D DAQ device connecting with SCXI 1125 for parallel scanning 1 5 unavailable digital lines D 2 unused analog input channels D 2 DAQ devices connecting to SCXI 1125 for multiplexed scanning in PXI combination chassis 1 4 3 2 in SCXI chassis 1 4 3 2 DC voltage connections See AC and DC voltage connections SCXI 1125 User Manual Index digital lines unavailability on DAQ device D 2 digital signals on SCXI 1125 table D 3 documentation conventions used in the manual iv E electromagnetic compatibility specifications A 9 environmental specifications A 8 F filter setting changing D 4 filters bandwidth configuration 3 1 4 2 floating signal connections AC coupled signal connection figure 2 4 description 2 3 front signal connector pin assignments figure 2 6 table 2 6 g
77. 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 Configure the cabled 1 7 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 module following the steps listed in the SCXT Quick Start Guide Click OK b If another module appears where the cabled module should be click the drop down listbox next to the correct slot and select the cabled module A message box appears asking you to confirm the module replacement Click OK Configure the cabled module following the steps listed in the SCXT Quick Start Guide Click OK e Ensure that you have the highest priority SCXI module cabled to the E M Series DAQ device Refer to the SCXT Quick Start Guide to find out which SCXI module in the chassis should be cabled to the E M Series DAQ device e After checking the preceding items return to the Troubleshooting the Self Test Verification section and retest the SCXI chassis If these measures do not successfully configure the SCXI system contact NI Refer to the Signal Conditioning Technical Support Information document for contact information SCXI 1125 User Manual 1 8 ni com Connecting Signals This chapter describes the input and output signals connections to the SCXI 1125 module with the module front connector and the rear signal connector This chapter also includes specifications and connection instructions for the signals on the SCXI 1125 module
78. nt inside the terminal block and maintain its isothermal nature for accurate CJC A thermocouple relies on the principle that a small voltage that varies with temperature is produced at the junction of two dissimilar metals CJC is necessary because the junction between the end of the thermocouple lead wires and the screw terminals produces a small potential difference adding error to the thermocouple voltage Knowing the temperature at the point where the thermocouple is connected to the measurement instrument allows you to determine the correct temperature reading at the thermocouple junction Due to the nonlinear relationship between National Instruments Corporation 5 1 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 SCXI 1125 User Manual thermocouple junction voltage and temperature this voltage conversion linearization is best done through software NI DAQ has built in scaling for most thermocouple types In NI DAQmx you can create a thermocouple task or global channel In Traditional NI DAQ Legacy you can create a thermocouple virtual channel If you choose to not let the driver scale the voltage readings for you in software you must do several conversions by using conversion coefficients that reflect the voltage temperature relationship for the type of thermocouple and CJC being used Complete the following steps to accurately determine thermocouple temperature 1 Read the voltage from the CJC sensor and convert t
79. oBvyOA Y3TY LZET IXOS WIM p YOO PUTULI aSeIOA YSIY OT ET KAL WIA yeod DY 10 DC 0 SIII A SWLOJOARM ePrOsNuUTs 0 SIJOI A z ADVANODS WOD TU ISIA SZ TXOS 2Y JOJ Aovndov oynposqe oy HLMIALI OL Oo SE 01 ST AowINd9R oINJOsqY ANTE A 9 0 L700 0 AN GZ An Or o ANTI A 7r 0 ASI vso 60 0 0007 AW OCF Avr AN LO L700 0 ANTE ANLIO AV 641 A TLO ASI ESO 80 0 0001 AW CF Atlog ANOT L700 0 AN OLY AN LTO AN SIZ AN eT Anoz ESO 80 0 oos AW OTF AUD OJAN D surpeoy ZHY OT ZH ZHA 0T 7H psyO xe ead u9 asuey eUIUION ILIS My PSO JO 1121240 ye Lemy aynjosqy yuq mrd IZLIV JUIOg AUIS SUMPELIY JO ew3is yeed ISION WAS S ni com A 4 SCXI 1125 User Manual Appendix A Specifications Analog Inputs Number of input channels 8 differential Input Tange ii2 see tesaiisaieatntd 2 5 mVDC to 5 VDC Input Coupling 0 0 eee eeeeeeeeeteeereeeneees DC or AC with SCXI 1305 or TBX 1329 Input impedance Normal powered oN eee gt 1 G II 100 pF in parallel Powered off overload ee 4 5M With SCXI 1327 oo eee 1M With TBX 1316 eesse 40M Input bias current 0 eee eee eres 100 pA typical 1 nA max Filter typeset 3 pole Butterworth filter response Bandwidth 3dB cut off frequency MAP TCT oes nein cee teentivtery 4 Hz 5 1O KAZ filter isenana 10 kHz 5 Full power bandwidth 7 kHz 5 With SCXI 1327 or SC
80. ok through the software documentation before you configure the hardware e One or more of the following help files for software information Start Programs National Instruments NI DAQ NI DAQm x Help Start Programs National Instruments NI DAQ Traditional NI DAQ User Manual Start Programs National Instruments NI DAQ Traditional NI DAQ Function Reference Help e NI application notes or tutorials NI has additional material on measurements available at ni com support You can download NI documents from ni com manuals To download the latest version of NI DAQ click Drivers and Updates at ni com National Instruments Corporation 1 3 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 Installing Application Software NI DAQ and the 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 1125 NI DAQ 7 0 or later is required to configure and program the SCXI 1125 module If you do not have NI DAQ 7 0 or later you can either contact a NI sales representative to request it on a CD or download the latest NI DAQ version from ni com 3 Note Refer to the Read Me First Safety and Radio Frequency Interference document before removing equipment covers or connecting or disconnecting any signal wires Installing the SCXI 1125 Module into the SCXI Chassis Re
81. operties 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 1000 e Terminal block gain this setting is only configurable if you selected a terminal block that supports adjustable attenuation e Modes of operation configure only using module properties The default setting in Traditional NI DAQ Legacy is multiplexed mode ay Note Refer to Chapter 4 Theory of Operation for information on configuring the settings for your application using Traditional NI DAQ Legacy Configuring Module Property Pages in Traditional NI DAQ Legacy 1 Right click the SCXI 1125 module you want to configure and select Properties Click General 2 Ifthe module you are configuring is connected to an E Series DAQ device select that device by using Connected to If you want this E Series DAQ device to control the chassis confirm there is a check in the This device will control the chassis checkbox If the module you are configuring is not connected to an E Series DAQ device select None 3 Click the Channel tab Select the appropriate gain and filter for each channel If you want to configure all the channels at the same time select the Channel drop down menu scroll to the bottom and select All Channels Refer to the SCX 1125 Software Configurable Settings section for a detailed description of each setting Click Apply 4 Click Acces
82. operty node complete the following steps 1 2 Launch LabVIEW Create the property node in a new Virtual Instrument VI or in an existing VI Open the block diagram view From the Functions tool bar select NI Measurements DAQmx Data Acquisition and select the type of property node you wish to configure Use the ActiveChans box to specify what channel s you want to configure If you want to configure several channels with different properties separate the lists of properties with another ActiveChans box and assign the appropriate channel to each list of properties Right click ActiveChan and select Add Element Left click the new ActiveChan box Navigate through the menus and select the property you wish to define You must change the property to read or write to either get the property or write a new value Right click the property go to Change To and select Write Read or Default Value After you have added the property to the property node right click the terminal to change the attributes of the property add a control constant or indicator To add another property to the property node right click an existing property and left click Add Element To change the new property left click it and select the property you wish to define Note Refer to the LabVIEW Help for information about property nodes and specific NI DAQmx properties National Instruments Corporation 5 13 SCXI 1125 User Manual Chapter
83. ou perform advanced analysis on the data without requiring you to have a programming background After you acquire the data and perform any required analysis it is useful to display the data in a graphical form or log it to a file 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 spread sheets for easy viewing ASCII files for universality or binary files for smaller file sizes Completing the Application After you have completed the measurement analysis and presentation of the data it is important to stop and clear the task This releases any memory used by the task and frees up the DAQ hardware for use in another task 3 Note In LabVIEW tasks are automatically cleared Developing an Application Using LabVIEW This section describes in more detail the steps shown in the typical program flowchart in Figure 5 1 such as how to create a task in LabVIEW and configure the channels of the SCXI 1125 If you need more information or for further instructions select Help VI Function amp How To Help from the LabVIEW menu bar Note Except where otherwise stated the VIs in Table 5 4 are located on the Functions All Functions NI Measurements DA Qmx Data Acquisition subpalette and accompanying subpalettes in LabVIEW National Instruments Corporation 5 9 SCXI 1125 User Manual Chapter 5 Us
84. peatedly in a channel string array 5 16 ni com Chapter 5 Using the SCXI 1125 Typical Program Flow After you have determined how you want to address the channels and whether you want to configure the SCXI 1125 in MAX or LabVIEW you can design your application using a typical program flow such as the one shown in Figure 5 3 Use Virtual Channel or SCXI Channel String Virtual Channel SCXI Channel String Configure Acquisition Settings Configure Mode Properties Create Virtual Channel in MAX Start Acquisition Take Measurements Continue Sampling No y Scale Analyze and Display y Clear Acquisition Error Handling Figure 5 3 Typical SCXI 1125 Program Flow with Traditional NI DAQ Legacy National Instruments Corporation 5 17 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Configure the SCXI 1125 Settings Using Traditional NI DAQ Legacy in LabVIEW You can configure SCXI 1125 settings in MAX using the virtual channel To configure and control the SCXI 1125 from LabVIEW use the AI Parameter VI You can find AI Parameter VI in the function subpalette Data Acquisition Analog Input Advanced Analog Input A parameter changed by the AI Parameter VI takes effect in hardware when AI Start VI is called not when AI Parameter VI is called The AI parameter VI merely changes the configuration in the driver me
85. r to verify signal and configuring and installing a system in NI DAQmx and Traditional NI DAQ Legacy Verifying the Signal in NI DAQmx Using a Task or Global Channel You can verify the signals on the SCXI 1125 using NI DAQmx by completing the following steps SCXI 1125 User Manual 1 2 3 4 Nn Expand Data Neighborhood Expand NI DAQmx Tasks Click the task Click the Add Channels or Remove Channels button to add remove channels In the window that appears click the next to the module of interest Select the channel s you want to verify You can select a block of channels by holding down the lt Shift gt key or multiple channels by holding down the lt Ctrl gt key Click OK Enter the appropriate information on the Settings tab 3 6 ni com Chapter 3 Configuring and Testing Click the Device tab Enter the appropriate information on the Device tab Click the Test button Click the Start button After you have completed verifying the channels click the Stop button You have now verified the SCXI 1125 configuration and signal connection Note For more information on how to further configure the SCXI 1125 or how to use 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
86. r time therefore requiring less frequent calibration Offset errors however are more susceptible to drift due to time temperature and other environmental changes and can affect the measurement accuracy of your module You may wish to periodically calibrate the module for offset drift using the following procedure to ensure that the measurements on the SCXI 1125 are as accurate as possible Refer to Appendix A Specifications for more details about the analog stability of your SCXI 1125 module Calibration Procedures You can calibrate the offset on the SCXI 1125 using National Instruments software When calibrating the offset on the SCXI 1125 make sure the DAQ device you are using has been calibrated recently or you will invalidate the offset calibration on the SCXI 1125 The SCXI 1125 provides input switching that allows you to programmatically shunt the differential input channels of the SCXI 1125 Once the channels are shunted the channel can be read by a calibrated DAQ device or calibrated DMM These offsets voltages read by the calibrated device can be saved in the calibration EEPROM in the SCXI 1125 for software correction of offset UN Caution Ensure that the calibration on the DAQ device or DMM you are using is up to date and traceable If you adjust the gain or offset values using an uncalibrated device you will invalidate the calibration on the SCXI 1125 and any measurements taken with the module may not be accurate SCXI 11
87. rature error of your reading Finally the accuracy of the DAQ device you use must be factored in to determine your overall system error 5 2 ni com Chapter 5 Using the SCXI 1125 Complete the following steps to calculate the overall temperature error using the SCXI 1125 with an E Series MIO DAQ device 1 National Instruments Corporation Based on the required temperature range and the type of sensor determine the gain to use For example using a K type thermocouple with a required temperature range of 0 to 100 C the corresponding voltage range is 1 002 mV to 4 0962 mV averaging 41 0 uV C in this range For this example use a gain of 1000 for this temperature range to get maximum temperature resolution Next look up the analog accuracy specifications from Appendix A Specifications for the gain and filter settings you have chosen You must consider how offset gain and system noise affect your measurement You might also consider common mode rejection temperature drift and other specifications based on the operating environment For example using a gain of 1000 the offset error is 0 2 uV the gain error is 0 03 which corresponds to 1 43 uV at full scale temperature and the system noise is 100 V use peak noise which is about 3 times this or 300 nV 54 because of the 4 Hz filter In this example you might or might not be able to average out the noise The total error is 1 73 uV at the full scale temper
88. repeated channels in different indices of the channel string array have the same input limits in the corresponding input limits array In LabVIEW can I use virtual channels with parallel mode channels on the SCXI 1125 Yes virtual channels work with parallel mode operation on the SCXI 1125 The E M Series DAQ device must be directly connected to the module in parallel mode operation Also virtual channels that use built in CJC are disabled and cannot be used in parallel mode In LabVIEW can I use the calgnd channel string when the SCXI 1125 is in parallel mode Yes you can autozero the SCXI 1125 in LabVIEW when using the module in parallel mode SCXI 1125 User Manual Appendix D Common Questions In LabVIEW can I use a VI to change my filter setting In NI DAQm x you can change the filter settings using a DAQmx Channel property node In Traditional NI DAQ Legacy there is no VI available to do this You must use the configuration utility in MAX to configure the filter setting of each channel In C can I randomly scan the SCXI 1125 using low level Traditional NI DAQ Legacy function calls No using C you can scan only consecutive channels using traditional SCXI channel programming Refer to the NI DAQ function reference manual for more details on SCXI scanning SCXI 1125 User Manual D 4 ni com Glossary Symbol Prefix Value p pico 10712 n nano 10 u micro 10 6
89. rization autozeroing and CJC transparently without additional code Virtual channels are useful when sensors requiring different scaling factors are used on the same SCXI 1125 channel Using virtual channels sensors needing special scaling can be used in a generic analog input application without performing hard coded scaling or linearization If the scaling changes or you want to connect a different sensor to the SCXI 1125 no changes are needed in the application All that is required is creating a different virtual channel and using its name in the channel string 5 26 ni com Chapter 5 Using the SCXI 1125 B Note You cannot mix virtual channels with the SCXI channel strings shown in the previous section To create a virtual channel for the SCXI 1125 insert a new analog input channel in the Data Neighborhood path in MAX name it and then follow the software prompts to create virtual temperature channels voltage channels or customized analog input channels For more information on virtual channels consult the MAX online help file To use the virtual channels enter the name of the virtual channel into the analog input channel string If using multiple virtual channels separate them using a comma or enter them in a different index in the channel string array The application does all scaling linearization autozeroing and CJC automatically 3 Note Virtual analog input channels can be randomly scanned therefore virtual channels c
90. rty Pages in Traditional NI DAQ Legacy eeseseeeereeesereerrserserssrsseesesees 3 5 Creating a Virtual Channel sssseeseesseessseesesesresrerrrresrrsrsresrrrrsrrsrere 3 6 Verifying the Signal crogain io ot ec seat ct oe ia isnt Sea bes athens pendns EEE E E ee doulas lesioned 3 6 Verifying the Signal in NI DAQmx Using a Task or Global Channel 3 6 Verifying the Signal in Traditional NI DAQ Legacy 0 0 eee eeeeeeereees 3 7 Verifying the Signal Using Channel Strings 0 0 eects 3 7 Verifying the Signal Using Virtual Channel 0 00 eee eee 3 8 Chapter 4 Theory of Operation Gan Sess oy aa P eases chia ata Seba sac heh spe Dead boleh E E A 4 1 Filter Bandwidth and Cutoff Frequency eee eceeeeceseeseeeseeeeceseeeeesecsecesesseeeaeesees 4 2 Operating in Multiplexed Mode oo eeeeeeesceeeseeeseeseceseeseeeeeaecseeeaeseseaesesneeeeeeaees 4 2 Multiplexed Hardware Operation Theory cc cececeseeseeseeeseceeeeeeseeeseesees 4 3 Operating in Parallel Mode 0 eee eeeeseceeceseeeeeesecseeeseeseesaecseceaecseeeaecaeseseeseseaeenees 4 3 Theory of Parallel Hardware Operation cece eee eeeeseeseeeseeeeeeseeseeeseesees 4 4 Chapter 5 Using the SCXI 1125 Temperature Measurements Using Thermocouples cececeeeeseeseeeeeeseeeeeeseeneeaes 5 1 Making High Voltage Measurements 200 0 ec eeceesceeceseeseeeseeseeeseeseeeaeeseceseeseeneeeaeenees 5 4 Developing Your Application in NI DAQMX o oo cece eeceseceeceseeeeesec
91. rved Important Information Warranty The SCXI 1125 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 This warranty includes parts and labor The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this document is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instr
92. s and LabWindows CVI Base or Full Development Systems Refer to the Configurable Settings in MAX section of Chapter 3 Configuring and Testing for more information about programmatically setting the cutoff frequency of the filter in MAX For more information about programmatically setting the cutoff frequency of the filter in 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 1125 Operating in Multiplexed Mode SCXI 1125 User Manual You can configure the SCXI 1125 to operate in multiplexed mode as described in Chapter 1 About the SCXI 1125 Using this mode of operation you can scan all input channels of the SCXI 1125 into one output channel that is read by the National Instruments DAQ device You can also multiplex the CJC channel that connects to a sensor on the SCXI terminal block for making temperature measurements 4 2 ni com Chapter 4 Theory of Operation Multiplexed Hardware Operation Theory When you configure a module for multiplexed mode operation the routing of multiplexed signals to the E M Series DAQ device depends on which module in the SCXI system is cabled to the E M Series DAQ device There are several possible scenarios for routing signals from the multiplexed modules to the E M Series DAQ device If the module being scanned is not directly cabl
93. s DAQ device 2 Insert the cable adapter into the rear of the SCXI 1125 module that is to be accessed in parallel mode by the E M Series DAQ device Refer to the installation guide for the cable assembly for more information 3 Connect the cable to the back of the cable adapter ensuring that the cable fits securely 4 Connect the other end of the cable to the E M Series DAQ device that you want to use to access the SCXI 1125 in parallel mode 5 Connect additional SCXI 1125 modules intended for parallel mode operation by repeating steps 2 through 4 6 Check the installation making sure the cable is securely fastened at both ends 7 Power on the SCXI chassis 8 Power on the computer If you have already installed the appropriate software you are ready to configure the SCXJ 1125 module s you installed for parallel mode operation Verifying the SCXI 1125 Installation in Software Refer to the SCXT Quick Start Guide for information on verifying the SCXI installation Installing SCXI Using NI DAQm x in Software Refer to the SCXI Quick Start Guide for information on installing modules using NI DAQmx in software National Instruments Corporation 1 5 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 Manually Adding Modules in NI DAQmx If you did not auto detect the SCXI modules you must manually add each of the modules Refer to the SCXI Quick Start Guide to manually add modules 3 Note NI recommends auto d
94. sii resccastersteesa witiiiheatsivos ads 641 g 22 6 oz National Instruments Corporation A 7 SCXI 1125 User Manual Appendix A Specifications Maximum Working Voltage Maximum voltage rating refers to the signal voltage plus the common mode voltage Signal common mode Voltage of each input shall remain within 300 V of ground Channel to earth 0 eee eeeeeeeeeees 300 V Measurement Category II Channel to channel 0 eee 300 V Measurement Category II Table A 2 Terminal Block Maximum Voltages Module Signal Range Maximum Voltage and Category Insulation SCXI 1313A 150 V 150 V Measurement Category II channel to channel channel to earth SCXI 1327 300 V 300 V Measurement Category II bank to bank bank to earth TBX 1316 600 V 600 V Measurement Category II Basic channel to channel 1000 V 1000 V Measurement Category I Basic channel to channel UN Cautions The SCXI 1125 is rated for Measurement Category II and is intended to carry signal voltages no greater than 300 V Do not use the SCXI 1125 for connection to signals or for measurements within Categories III or IV When hazardous voltages gt 42 4 V px 60 VDC are present on any channel all channels are considered hazardous Ensure that external wiring or any circuits connected to the device are properly insulated from human contact Environmental SCXI 1125 User Manual Operating temperature 0 0 ee 0 to 50 C Storag
95. sory Select the accessory you connected to the module If the accessory has a configurable gain select the desired gain When configuration is complete click OK The Traditional NI DAQ Legacy chassis and SCXI 1125 should now be configured properly If you need to change the module configuration right click the module and repeat steps 1 through 4 Test the system following the steps in the Troubleshooting the Self Test Verification section of Chapter 1 About the SCXI 1125 National Instruments Corporation 3 5 SCXI 1125 User Manual Chapter 3 Configuring and Testing Creating a Virtual Channel To create a virtual channel complete the following steps Se OO AN ee Oo o 11 Right click Data Neighborhood and select Create New Select Traditional NI DAQ Virtual Channel and click Finish Click Add Channel Select Analog Input from the drop down list and click Next Enter the Channel Name and Channel Description and click Next Select Voltage from the drop down list and click Next Enter the units and input range and click Next Select the appropriate scaling option and click Next Enter the following information What DAQ hardware will be used from the drop down list a What channel on your DAQ hardware from the drop down list b Which analog input mode will be used from the drop down list Click Finish Verifying the Signal This section describes how to take measurements using test panels in orde
96. t 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 NI recommends using the intermediate analog input functions for most SCXI 1125 applications For more information about using the intermediate data acquisition Traditional NI DAQ Legacy functions refer to the LabVIEW Measurements Manual You also can use the LabVIEW Help for more detailed information about the various inputs and outputs of these functions National Instruments Corporation 5 19 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Convert Scaling Using Traditional NI DAQ Legacy in LabVIEW If you need scaling you can either use an analog input voltage virtual channel with a custom scale configured in MAX or SCXI channel strings and provide scaling in your LabVIEW application If you are using SCXI channel strings you can easily convert the SCXI 1125 voltage signal measurements in your application into scaled units of interest such as pounds or newtons LabVIEW has some common conversion scaling functions such as the Scaling Constant Tuner VI in the function subpalette Data Acquisition Signal Conditioning You also can use an Expression Node or Formula Node to convert voltage signal measurements into whatever units your application requires You can find an Expression Node in the function subpalet
97. t limits NI recommends using the obx specifier Repeating channels or having channels out of sequence in a scan list is not supported on all SCXI modules Refer to the manual of each module for information on this feature which is referred to as flexible scanning or random scanning For more information about using SCXI channel string refer to the LabVIEW Measurements Manual and SCXI 1125 shipping examples SCXI 1125 User Manual B 2 ni com Removing the SCXI 1125 This appendix explains how to remove the SCXI 1125 from MAX and an SCXI chassis 3 Note Figure C 1 shows an SCXI chassis but the same steps are applicable to a PXI SCXI combination chassis Removing the SCXI 1125 from MAX To remove a module from MAX complete the following steps after launching MAX 1 Expand Devices and Interfaces to display the list of installed devices and interfaces 2 Expand NI DAQmx Devices and or Traditional NI DAQ Devices to display the chassis Expand the appropriate chassis to display the installed modules 4 Right click the module or chassis you want to delete and click Delete You are presented with a confirmation window Click Yes to continue deleting the module or chassis or No to cancel this action 3 Note Deleting the SCXI chassis deletes all modules in the chassis All configuration information for these modules is also deleted The SCXI chassis and or SCXI module s should now be removed from the list of installe
98. t that is a placeholder for a word or value that you must supply Contents Chapter 1 About the SCXI 1125 What You Need to Get Started oier eeaeee a aanp a eoio 1 1 National Instruments Documentation 0 cies eecceseeeeeesecesecseeeaeeseeeseeseeeaeeeeeaseeenaes 1 2 Installing Application Software NI DAQ and the DAQ Device 0 eects 1 4 Installing the SCXI 1125 Module into the SCXI Chassis eee 1 4 Connecting the SCXI 1125 in an SCXI Chassis to an E M Series DAQ Device for Multiplexed Scanning ee 1 4 Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M Series DAQ Device for Multiplexed Scanning 0 0 0 1 4 Connecting the SCXI 1125 to an E M Series DAQ Device for Parallel Scanning nopi na n a a a ae 1 5 Verifying the SCXI 1125 Installation in Software essessssessseeseeesrestesesrrsreresrrererenerees 1 5 Installing SCXI Using NI DAQmx in Software eee eee eeeeeeeeeereeeeeees 1 5 Manually Adding Modules in NI DAQMX 00 0 eceseeeeeseeseeseeeeeeseeeseenees 1 6 Installing SCXI Using Traditional NI DAQ Legacy in Software 1 6 Manually Adding Modules in Traditional NI DAQ Legacy eee 1 6 Verifying and Self Testing the Installation 0 0 eee eseeseeeeeeeeeseeees 1 6 Troubleshooting the Self Test Verification cece eeeseeecceseesseeeceeeeseeneeeseseeeeseesees 1 7 Troubleshooting in NI DAQMX 2 0 eeeeeeseceseeeseeteneceseeeeeceeeeaeersneseseeeneeesaes 1 7 C
99. tants loaded on the module EEPROM that are used to achieve the absolute accuracy specifications SCXI_Scale scales an array of binary data acquired from an SCXI channel to voltage using the stored software calibration constants when it scales the data You must call SCAN_Demux before SCXI_Scale if you have multiple channels in the scan For more information regarding SCXI_Scale refer to the Traditional NI DAQ Legacy Function Reference Help installed by default in Start Programs National Instruments NI DAQ After you have adjusted the measurement by the appropriate calibration constants using SCXI_Scale you can use a function from the NI conversion library convert h to convert a voltage or voltage buffer from a voltage to units of temperature or strain NI ADEs also provide many powerful analysis functions to perform digital filtering harmonic analysis averaging and complex mathematics on measurements After performing scaling and analysis on the acquired data you can display the measurements in several ways You can use any built in GUI tools in your ADE NI ADEs provide many graphical controls and indicators such as charts graphs gauges slides and plots that you can use to display the data There is also a built in function found in nidaqex h called NIDAQP1lotWaveform that you can use to generate a simple plot of the data Using Software for Multiplexed Scanning SCXI 1125 User Manual Performing scanning operations in softw
100. task timing and task triggering You can access the DAQ Assistant through MAX or your NI ADE Choosing to use the DAQ Assistant can simplify the development of your application NI recommends creating tasks using the DAQ Assistant for ease of use when using a sensor that requires complex scaling or when many properties differ between channels in the same task If you are using an ADE other than an NI ADE or if you want to explicitly create and configure a task for a certain type of acquisition you can programmatically create the task from your ADE using functions or VIs If you create a task using the DAQ Assistant you can still further configure the individual properties of the task programmatically with functions or property nodes in your ADE NI recommends creating a task programmatically if you need explicit control of programmatically adjustable properties of the DAQ system Programmatically adjusting properties for a task created in the DAQ Assistant overrides the original or default settings only for that session The changes are not saved to the task configuration The next time you load the task the task uses the settings originally configured in the DAQ Assistant Adjusting Timing and Triggering There are several timing properties that you can configure through the DAQ Assistant or programmatically using function calls or property nodes If you create a task in the DAQ Assistant you can still modify the timing properties of
101. te Numeric You can find Formula Nodes in the Function subpalettes Analyze Mathematics Formula For more information about using the Expression Node or Formula Node refer to the LabVIEW User Manual You also can use the LabVIEW Help for more detailed information about how to use these nodes to perform mathematical calculations such as scaling conversions Analyze and Display Using Traditional NI DAQ Legacy in LabVIEW In LabVIEW you can easily analyze SCXI 1125 measurements with a variety of powerful analysis functions that you can find in the function subpalettes Analyze Waveform Conditioning and Analyze Signal Processing You can perform post acquisition processing such as waveform comparisons harmonic analysis and digital filtering For more information about these VIs refer to the LabVIEW Analysis Concepts manual 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 1125 measurements with a variety of graphical waveform graphs numeric slides gauges and other indicators You can find useful graphical controls and indicators for user interaction with your application in the controls subpalettes For more information about these VIs refer to the LabVIEW User Manual You also can use the LabVIEW Help for more detailed information about how to use graphical controls and indicators in your application SCXI 1125 User Manual 5 20 ni com Chap
102. tem Resolution can be expressed in bits in proportions or in percent of full scale For example a system has 12 bit resolution one part in 4 096 resolution and 0 0244 of full scale return Material Authorization root mean square reserved bit signal referred to input Calculates a specification relative to the input range seconds An instantaneous measurement of a signal normally using an analog to digital converter in an E Series DAQ device The number of samples a system takes over a given time period usually expressed in samples per second One or more analog or digital input samples Typically the number of input samples in a scan is equal to the number of channels in the input group For example one pulse from the scan clock produces one scan which acquires one new sample from every analog input channel in the group Scan clock signal used to increment the next channel after each E Series DAQ device analog to digital conversion G 8 ni com SCXI SCXIbus SER CLK SER DAT IN SER DAT OUT sensor settling time shunt shunt calibration signal conditioning Slot 0 strain SYNC system noise National Instruments Corporation G 9 Glossary Signal Conditioning eXtensions for Instrumentation the National Instruments product line for conditioning low level signals within an external chassis near sensors so only high level signals are sent to DAQ boards in the noisy PC environment The an
103. ter 5 Using the SCXI 1125 Traditional NI DAQ Legacy in Text Based ADEs NI text based ADEs such as LabWindows CVI Measurement Studio for Microsoft Visual Basic and Measurement Studio for Microsoft Visual C offer help in the development of test and measurement applications These ADEs provide easy data acquisition data analysis graphical display and data logging tools Refer to the ADE user manual for more information about how to use these features The high level data acquisition tools provided in LabWindows CVI and Measurement Studio allow you to easily use virtual channels configured in MAX providing easy configuration and programming of the data acquisition systems However some of the more advanced features of the SCXI 1125 are not accessible through this easy to use API For more advanced features or for more explicit control of the programmatic attributes use the low level DAQ functions provided in the Traditional NI DAQ Legacy C API Refer to the ADE user documentation for more information about how to use the high level data acquisition tools that are provided in your NI ADE For more advanced SCXI 1125 applications or if you are using an ADE other than an NI ADE you can use the Traditional NI DAQ Legacy C API to call functions from the DAQ driver dynamically linked library dll Configuring System Settings Using Traditional NI DAQ Legacy C API Start the configuration of the acquisition by ensuring that the SCXI
104. the task programmatically in your application When programmatically adjusting timing settings you can set the task to acquire continuously acquire a buffer of samples or acquire one point at a National Instruments Corporation 5 7 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 time For continuous acquisition you must use a while loop around the acquisition components even if you configured the task for continuous acquisition using MAX or the DAQ Assistant For continuous and buffered acquisitions you can set the acquisition rate and the number of samples to read in the DAQ Assistant or programmatically in your application By default the clock settings are automatically set by an internal clock based on the requested sample rate You also can select advanced features such as clock settings that specify an external clock source internal routing of the clock source or select the active edge of the clock signal Configuring Channel Properties All ADEs used to configure the SCXI 1125 access an underlying set of NI DAQmx properties Table 5 3 shows some of these properties You can use Table 5 3 to determine what kind of properties you need to set to configure the module for your application For a complete list of NI DAQmx properties refer to your ADE help file 3 Note You cannot adjust some properties while a task is running For these properties you must stop the task make the adjustment and re start the application Figur
105. tional Instruments Corporation 1 1 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 3 Note For maximum allowable voltage for a particular terminal block refer to Table A 2 Terminal Block Maximum Voltages SCXI or PXI SCXI combination chassis One of the following e E M Series DAQ device e SCXI 1600 module A computer if using an SCXI chassis Cabling cable adapter and sensors as required for your application Software NI DAQ 7 0 or later One of the following software packages e LabVIEW LabWindows CVI e Measurement Studio Documentation Read Me First Safety and Radio Frequency Interference DAQ Getting Started Guide SCXI Quick Start Guide SCXI 1125 User Manual Documentation for your hardware Documentation for your software National Instruments Documentation SCXI 1125 User Manual The SCXI 1125 User Manual is one piece of the documentation set for data acquisition DAQ systems You could have any of several types of manuals depending on the hardware and software in the system Use the manuals you have as follows SCXI or PXI chassis manual Read this manual for maintenance information on the chassis and for installation instructions The DAQ Getting Started Guide This document has information on installing NI DAQ and the E M Series DAQ device Install these before you install the SCXI module 1 2 ni com Chapter 1 About the SCXI 1125 e The SCX
106. tring 5 26 parallel scanning operations C and parallel mode 5 29 LabVIEW and parallel mode 5 28 specifications electromagnetic compatibility A 9 environmental A 8 input characteristics A 1 maximum working voltage A 8 physical A 7 regulatory compliance A 9 safety A 9 stability A 6 transfer characteristics A 6 stability specifications A 6 SCXI 1125 User Manual l 4 T temperature measurements using thermocouples 5 1 accurate method for temperature determination 5 2 guide for calculating overall temperature error 5 3 overview 5 1 temperature sensor connection 2 7 thermocouples for temperature measurements See temperature measurements using thermocouples transfer characteristics A 6 troubleshooting NI resources See common questions self test verification 1 7 V verifying and self testing the configuration troubleshooting 1 7 virtual channel string 5 26 ni com
107. ts original power digital to analog data Address digital ground signal SCXI 1125 User Manual Glossary DAQ DAQ device dB DC device differential input DIN DIO DMM E EEPROM EMC EMI SCXI 1125 User Manual Data acquisition 1 collecting and measuring electrical signals from sensors transducers and test probes or fixtures and inputting them to a computer for processing 2 collecting and measuring the same kinds of electrical signals with A D and or DIO boards plugged into a computer and possibly generating control signals with D A and or DIO boards in the same computer A device that collects signals for data acquisition devices Examples are MIO and 1200 boards decibel The unit for expressing a logarithmic measure of the ratio of two signal levels dB 20 log V1 V2 for signals in volts direct current A plug in data acquisition board module card or pad that can contain multiple channels and conversion devices An input circuit that actively responds to the difference between two terminals rather than the difference between one terminal and ground deutsche Industrie Norme digital I O digital multimeter A digital instrument capable of measuring several different fundamental electrical characteristics most often voltage resistance and current electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed
108. tware for scanning C and parallel mode 5 29 LabVIEW and parallel mode 5 28 physical specifications A 7 pin assignments front connector table 2 6 PXI combination chassis 1 4 3 2 R rear signal connector description 2 7 pin assignments figure 2 8 table 2 8 regulatory compliance specifications A 9 National Instruments Corporation l 3 Index removing SCXI 1125 from Measurement amp Automation Explorer C 1 from SCXI chassis C 1 S safety specifications A 9 SCXI channel string 5 25 SCXI chassis connecting SCXI 1125 to DAQ device 1 4 3 2 SCXI 1125 calibration 5 30 common questions D 1 digital signals table D 3 multiplexed mode 4 2 parallel mode 4 3 signal connections 2 1 specifications A 1 self test verification troubleshooting 1 7 D 2 signal connections See also connectors AC and DC voltage connections 2 1 AC coupling 2 4 floating AC coupled signal connection figure 2 4 floating signal 2 3 floating signal connection figure 2 3 front signal connector figure 2 6 ground referenced AC coupled signal connection figure 2 4 ground referenced signal 2 2 ground referenced signal connection figure 2 2 digital signals table D 3 SCXI 1125 User Manual Index front connector pin assignments table 2 6 overview 2 1 temperature sensor connection 2 7 software multiplexed scanning operations 5 24 LabVIEW and SCXI channel string 5 25 LabVIEW and virtual channel s
109. uments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner
110. used channels on the E M Series DAQ device If you are directly connected to a higher input channel device such as a 64 channel 32 differential inputs E M Series DAQ device only the lower eight differential inputs are unusable Which digital lines are unavailable on the E M Series DAQ device if I am cabled to an SCXI 1125 module Table D 2 shows the digital lines that are used by the SCXI 1125 for communication and scanning These lines are unavailable for general purpose digital I O if the SCXI 1125 is connected to the E M Series DAQ device D 2 ni com Table D 2 Digital Signals on the SCXI 1125 Appendix D Common Questions Traditional DAQ Signal DAQmx SCXI Signal 50 Pin 68 Pin Name Signal Name Name Connector Connector Direction DIOO P0 0 SER DAT IN 25 52 Output DIO4 P0 4 SER DAT OUT 26 19 Input DIO1 P0 1 DAQ D A 27 17 Output DIO2 P0 2 SLOT 0 SEL 29 49 Output SCANCLK AI HOLD SCAN CLK 36 46 Output COMP AI HOLD EXTSROBE EXTSROBE SER CLK 37 45 Output STARTSCAN AI SAMP SYNC 46 38 Output CLK AI SAMP National Instruments Corporation D 3 In LabVIEW can I use different input limits for the same SCXI 1125 channel if I repeat the channel in the SCXI channel string array No the SCXI 1125 cannot dynamically change the gain settings during scanning Therefore channels with similar input ranges should be grouped together in the channel string array Make sure that
111. used with a terminal block that provides attenuation the input range expands up to 1000 V Refer to Appendix A Specifications for a full list of input ranges National Instruments Corporation 4 1 SCXI 1125 User Manual Chapter 4 Theory of Operation Refer to the Configurable Settings in MAX section of Chapter 3 Configuring and Testing for more information about programmatically setting gain using range settings in MAX For more information about programmatically setting gain using range settings in 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 1125 Filter Bandwidth and Cutoff Frequency The SCXI 1125 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 4 Hz or 10 kHz For additional flexibility in cutoff frequency settings and for greater suppression NI recommends combining the hardware filtering provided by the SCXI 1125 with digital filtering NI recommends using the Advanced Analysis functions of LabVIEW LabWindows CVI or Measurement Studio By combining hardware anti aliasing with digital filtering you can choose any cutoff frequency The Advanced Analysis functions are only available in LabVIEW Full or Professional Development System
112. ust use an external reference to perform a two point calibration Please refer to the SCXI 1125 Calibration Procedures document for more information on doing an external two point gain and offset calibration 5 32 ni com Specifications This appendix lists the specifications for the SCXI 1125 modules These specifications are typical at 25 C unless otherwise noted Input Characteristics Table A 1 Input Signal Range Versus Gain SCXI 1125 Overall Gain Overall Voltage Range Gain 1 5 V peak or WDC 1 2 2 5 V peak or WDC 2 5 1 Vpeak or VDC 5 10 500 mV peak OF VDC 10 20 250 mV peak Or VDC 20 50 100 MV pea Or VDC 50 100 50 MV peak Or WDC 100 200 25 MV peak Or WDC 200 250 20 MV peak Or WDC 250 500 10 MV peak Or WDC 500 1000 5 MV peak Or VDC 1000 2000 2 5 MV peak Or WDC 2000 3 Note Refer to Tables 5 1 and 5 2 for extended range using the SCXI 1313A SCXI 1327 and TBX 1316 National Instruments Corporation A 1 SCXI 1125 User Manual Appendix A Specifications Overvoltage protection Isolated connector pins Powered on and Off eeeeeeeeeeee 300 V Inputs protected eee eee CHO CH7 Non isolated connector pins Powered on and Off eee ceeeeeeeeee 5 5V 0 5 V SCXI 1125 User Manual A 2 ni com Specifications Appendix A AN0rT ANG T L700 0 A
113. x showing the SCXI chassis model number Chassis ID x and one or more messages stating Slot Number x Configuration has module SCXI XXXX or 1125 hardware in chassis is Empty take the following troubleshooting actions National Instruments Corporation Make sure the SCXI chassis is powered on Make sure all SCXI modules are properly installed in the chassis Refer to the SCX7 Quick Start Guide for proper installation instructions Make sure the cable between the SCXI chassis and E M Series DAQ device is properly connected Inspect the cable connectors for bent pins Make sure you are using the correct NI cable assembly Test the E M Series DAQ device to verify it is working properly Refer to the E M Series DAQ device help file for more information If you get a Verify SCXI Chassis message box showing the SCXI chassis model number Chassis ID x and the message Slot Number x Configuration has module SCXI XXXX or 1125 hardware in chassis is SCXI YYYY 1125 or Empty complete the following troubleshooting steps to correct the error 1 Expand the list of NI DAQm x devices by clicking the next to NI DAQmxx Devices Right click the SCXI chassis and click Properties to load the chassis configurator Under the Modules tab ensure that the cabled module is listed in the correct slot If the cabled module is not listed in the correct slot complete the following troubleshooting steps a If the cabled module is
114. y while selecting channels 9 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 Refer to Chapter 3 Configuring and Testing for more information 10 Click the Device tab and select the autozero mode and lowpass filter cutoff frequency 11 If you are creating a task and want to set timing or triggering controls enter the values in the Task Timing and Task Triggering tabs Traditional NI DAQ Legacy In Traditional NI DAQ Legacy you can configure software settings such as configuration voltage excitation level filter bandwidth gain input signal range and calibration settings in the following three ways e module property pages in MAX e virtual channels properties in MAX e functions in your ADE 3 Note All software configurable settings are not configurable in all three ways This section only discusses settings in MAX Refer to Chapter 4 Theory of Operation for information on using functions in your application Most of these settings are available in module properties and or using virtual channels e Filter bandwidth configure only using module properties You also can set bandwidth through your application The default filter bandwidth level for Traditional NI DAQ Legacy is 4 Hz SCXI 1125 User Manual 3 4 ni com Chapter 3 Configuring and Testing e Gain input signal range configure gain using module pr

National Instruments Module SCXI-1125 User's Manual

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