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SCXI-1125 User Manual - National Instruments

1. 16 o 16 NC NC 15 15 14 o o 13 14 AI6 AI6 12 o o 13 11 12 AI7 AI7 10 o o 11 B 9 10 NC NC 8 0 o 7 9 6 o o 8 RSVD RSVD 5 7 7 o o 4 o 3 6 RSVD RSVD 2 o o 5 1 4 5 V CJ TEMP L 3 as NC means no connection 2 CHS GND z 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 X 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 X Se
2. e scyis the SCXI chassis ID where y is the number you chose when configuring the 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 National Instruments Corporation B 1 SCXI 1125 User Manual Appendix B Using SCXI 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 where n0 n2 are 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 nl 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 3 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 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
3. Note For more information about 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 Verifying the Signal Using Channel Strings The format of the channel string is as follows obx scy mdz channel where National Instruments Corporation 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 3 7 SCXI 1125 User Manual Chapter 3 Configuring and Testing Use the format obx scy mdz n to verify the signal where n is a single input channel Complete the following steps to use channel
4. 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 system 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 M X 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 Instrum
5. installation instructions DAQ Getting Started guides These documents have information about installing NI DAQ and the E M X Series DAQ device Install NI DAQ and the DAQ device before you install the SCXI module The SCXI 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 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 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 The E M X Series DAQ device documentation This documentation has detailed information about the E M X 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 X Series DAQ device and application hints Software documentation You may have both application software and NI DAQ software documentation National Instruments NI application software includes LabVIEW LabWindows CVI and M
6. 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 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 acommon 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 inacc
7. 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 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 SCX
8. 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 DAQmx Data Acquisition subpalette and accompanying subpalettes in LabVIEW National Instruments Corporation 5 9 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Table 5 4 Programming a Task in LabVIEW Flowchart Step VI or Program Step Create Task in DAQ Assistant Create aDAQmx Task Name Constant located on the Controls All Controls I O DAQmx Name Controls subpalette right click it and select New Task DAQ Assistant Create a Task DAQmx Create Task vi tThis VI is optional if you created Programmatically and configured your task using the DAQ Assistant However if optional you use it in LabVIEW any changes you make to the task will not be saved to a task in MAX Create AI Channel DAQmx Create Virtual Channel vi AI Voltage by default optional 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 Sampl
9. 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 current virtual instrument 1 a combination of hardware and or software elements typically used with a computer that has the functionality of a classic standalone instrument 2 a LabVIEW software module VT 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 absolute accuracy A 3 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 multi
10. CH4 11 12 CH 4 13 14 15 16 CH 5 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 29130 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 socal NC 31 32 NC 41 42 43 44 D GND 33 34 NC nee 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 about 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 DAQmx 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 lo
11. 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 UPON 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 A A bold italic monospace 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 PO lt 3 0 gt Square brackets enclose optional items for example response The symbol leads yo
12. 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 provide features such as screw terminal connectivity BNC connectivity cold junction 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 National Instruments Corporation 2 1 SCXI 1125 User Manual Chapter 2 Connecting Signals connections to each channel are fully floating with respect to ground and completely isolated from other channels You can operate with common mode voltage levels up to 300 Vims Figures 2 1 through 2 4 show signal connection methods that give the highest noise immunity Ground Referenced Signal 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 on a high common mode voltage that is ground referenced 1 N N l lt Figure 2 1 Connecting a Ground Referenced Si
13. 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 memory 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 Lab VIEW 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 ET filter setting device 1 H DBE p 000000 fl Param Al channels 0 Cono ST
14. 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 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 X 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 deta
15. 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 can 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 1
16. 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 All 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 Channel 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 SCXI_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 SCKI_Calibrate refer to the Trad
17. software multiplexed scanning operations 5 24 LabVIEW and SCXI channel string 5 25 LabVIEW and virtual channel string 5 26 parallel scanning operations C and parallel mode 5 29 LabVIEW and parallel mode 5 28 specifications absolute accuracy A 3 environmental A 8 input characteristics A 1 maximum working voltage A 8 physical A 7 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
18. the next to NI DAQm x 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 1 7 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 SCXI 1125 User Manual 4 Ifthe cabled module is not listed in the correct slot complete the following troubleshooting steps a If the cabled module is not listed in the correct slot and the slot is empty click the drop down listbox next to the correct slot and select the cabled module Configure the cabled module following the steps listed in the SCX7 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 X 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 X 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 Technical Support Information docume
19. the routing of multiplexed signals to the E M X Series DAQ device depends on which module in the SCXI system is cabled to the E M X Series DAQ device There are several possible scenarios for routing signals from the multiplexed modules to the E M X Series DAQ device If the module being scanned is not directly cabled to the E M X 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 X Series DAQ device through the CH 0 signal on the rear signal connector If the E M X Series DAQ device scans the cabled module the module routes its input signals through the CH 0 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 X Series DAQ device 3 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 X Series DAQ device in multiplexed mode the differential inputs 1 through 7 on the E M X Series DAQ device cannot be used for general purpose analog input Refer to Appendix D Common Questions for more information about 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 op
20. this terminal block already has an AC coupling option built in OL ge Yh gt L Figure 2 3 Connecting a Floating AC Coupled Signal Connecting a signal source to chassis ground in Figures 2 2 and 2 3 breaks the isolation barrier SCXI 1125 User Manual Figure 2 4 Connecting a Ground Referenced AC Coupled Signal 2 4 ni com Chapter 2 Connecting Signals NI recommends using a bias resistor 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 Connecting 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 ei
21. 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 on 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 about 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 chann
22. 125 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 SCKI_Set_Gain and SCXI_Configure_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 SCKI_Scale Refer to the Traditional NI DAQ User Manual for additional information about scanning with DAQ devices Using Software for Parallel Scanning SCXI 1125 User Manual Performing scanning operations in
23. ART X 2 eee a A number of scans Lf code To 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 Start VI AI Read VI and AI Clear VI to create your data acquisition application You can find the intermediate data acquisition Traditional NI DAQ Legacy functions in the function subpalettes Data Acquisition Analog Input 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 Help 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
24. DAQ device usually the lowest gain is used but the SCXI 1125 gain is adjusted to fit the input 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 about this feature which is referred to as flexible scanning or random scanning For more information about using SCXI channel string refer to the LabVIEW Help 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 T
25. 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 e Modes of operation configure only using chassis installation in software Refer to Chapter 1 About the SCXI 1125 for more information about chassis installation The default setting in NI DAQmx is multiplexed e Terminal 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 about configuring the settings for your application using Traditional NI DAQ Legacy Creating a Voltage Global Channel or Task To create a new NI DAQmx 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 Next National Instruments Corporation 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 chan
26. I 1125 The last parameter channels is the list of channels that are scanned for module z It can have several formats e 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 can use mt emp in place of cj temp e 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 nJ 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 calgndnI 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 ay Note Repeating channels or having channels out of sequence in a scan list is not suppo
27. I SJUSIOY JOOS ILIP IUNI JOSHO ML oinjerodurs JUSIQUIR Do SZ SOUUINSse IOI JASJJO eNPISeI AL z UOHPIQIe BUID XS Joye Ip TV pue sinjesoduis jusque J Z SIUNSSE 10119 UTES eNpIsel AL 0s0 0 TITO O cv000 0 SOOT O0EE o0z oz 000S 0007 c00 0 AW ZHA OT ZH Yb Q asuey muowsuey esuey jo 0 surpeay surpeay ure A Suey AVIS MA jo wdd Jo wdd ajua wdd 1011 jo wdd jo wdd E1340 euUruoN ye AWIMIV yuroqd ABUS ooduray IUL SO PSO ooduray Pongu aynjosqy ET Au LOF SION PSO enpisoy ure Tenpisoy ni com A 4 SCXI 1125 User Manual Appendix A Specifications Analog Inputs Number of input channels 8 differential TApUlt tange sari 2 5 mVDC to 5 VDC Input coupling 00 0 ee eeeeeeeeeeeseeeneeeenees DC or AC with SCXI 1305 or TBX 1329 Input impedance Normal powered on sses gt 1 G I 100 pF in parallel Powered off overload e ee 4 5M With SCXI 1327 oe 1M With TBX 1316 oe 40M Input bias current ssseseeeseeeeeeeeeeereeeee 100 pA typical 1 nA max Piller type innnan 3 pole Butterworth filter response Bandwidth Filter options 00 0 eee eeeeeeeeees 4 Hz and 10 kHz 10 kHz filter Full power bandwidth 7 kHz With SCXI 1327 or SCXI 1313A high voltage terminal blocks c00008 2 6 kHz With TBX 1316 high voltage terminal block ccceeee 500 Hz Slew rate Typical ois einasi 0 15 V u
28. 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 Instruments res
29. 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 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 s
30. SCXT SCXI 1125 User Manual October 2009 7 NATIONAL 372425C 01 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 22 328 90 10 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 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 2009 National Instruments Corporation All rights reserved
31. 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 restart the application Figure 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 n ot 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 DAQmx properties refer to your ADE help file SCXI 1125 User Manual 5 8 ni com Chapter 5 Using the SCXI 1125 Acquiring Analyzing and Present
32. a RoHS compliance go to ni com environment rohs_china SCXI 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 obxis 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
33. adings 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 temperature 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 M X 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 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
34. adings Using Traditional NI DAQ Legacy in LabVIEW sssessssessesesesessrssesrsrssrsresrestsresreresresenresresrsee 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 ceeceecceeeseeeeeeseeeees 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 NEIEDAQ Legacy CAPD sscccssiccsssseceessscstscassctionestessssgesdbesviseceascaseassepaedeabeveas 5 23 Perform Acquisition Using Traditional NI DAQ Legacy C API 5 23 Perform Scaling Analysis and Display cceeeeeccesseeseeeseesecneceseeeenseesees 5 24 Using Software for Multiplexed Scanning eee ee eeeeeeeeeecreeeeeseeeseenees 5 24 LabVIEW and the SCXI Channel String eeeeeeeeeeees 5 25 LabVIEW and the Virtual Channel String eeeeeereees 5 26 Performing a Multiplexed Scan eee cece sseceseeseceeceseeseeeaeeseeesesseeeaeseeeeaee 5 27 C and Low Level DAQ Functions 0 ccccceesssecesseeeeeseeeseeeeeseeees 5 28 Using Software for Parallel Scanning 0 ee eee ecceeceeeseeeseceeeeseeeenseesees 5 28 LabVIEW and Parallel Mode cece ees eneceseeeeeeeeeeeeeseenaeesees 5 28 Cand Parallel Mode vc i3 c ss2isescestsceseseteesethessdssbagegedeesdescasaetbceesestgea
35. alibrated 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 AN 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 1125 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 Chapter 5 Using the SCXI 1125 One Point Offset Calibration 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 a Enter the DAQ device and the SCXI channel string for the channels you want to calibrate You can calibrate only one channel at a time b Select internal calibration as the calibration operation you are going to perform c Select the Default EEPROM load area as the area you want to update d The offset varies with the selected gain value Therefore enter the high and low
36. all 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 Started guides and the SCXI Quick Start Guide for more information about 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 Chapter 3 Configuring and Testing NI DAQmx In NI DAQmx you can configure software settings such as filter bandwidth and gain input signal range in the following ways e Task or global channel in MAX e 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 about using functions in your application These sections describe settings that you can change in MAX and where they are located e 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 e Input signal range configure the input signal range using either NI DAQmx Task or NI DAQmx Global Channel When you set the minimum and maximum range of NI
37. are Refer to the SCXT Quick Start Guide for information about installing modules using NI DAQmx in software 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 ay Note NI recommends auto detecting 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 about 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 SCXT Quick Start Guide to manually add modules y s 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 X Series DAQ device SCXI 1125 User Manual 1 6 ni com Chapter 1 About the SCXI 1125 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 t
38. asurements 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 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 27 when used with B to quantify data or computer memory multiplexed temperature sensor signal See also CJ TEMP maximum 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 conv
39. ation 1 5 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 software 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 5 3 2 R rear signal connector description 2 7 pin assignments figure 2 8 table 2 8 removing SCXI 1125 from Measurement amp Automation Explorer C 1 from SCXI chassis C 1 National Instruments Corporation l 3 Index S 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 4 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 front connector pin assignments table 2 6 overview 2 1 temperature sensor connection 2 7 SCXI 1125 User Manual Index
40. aved 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 the task programmatically in your application National Instruments Corporation 5 7 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 When programmatically adjusting timing settings you can set the task to acquire continuously acquire a buffer of samples or acquire one point at a 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
41. 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 temperature range which gives a preliminary accuracy of 0 04 C 1 73 uV divided by 41 0 uv C 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 c
42. cation 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 CVI 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 The mark LabWindows is used under a license from Microsoft Corporation Windows is a registered trademark of Microsoft Corporation in the United States and other countries Other product and company names mentioned herein are trademarks or trade names of their respective companies Members of the National Instrume
43. 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 property node complete the following steps Ls 2 Launch LabVIEW Create the property node in a new Virtual Instrument VT 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 the 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 c
44. dwidth 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 gain 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 5 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 SCXI 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 theory of multiplexed hardware operation 4 3 ni com 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 combin
45. e e Gain set at 1000 0 e 4 Hz 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 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 3 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
46. e 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 and 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 DAQmx Read vi Analyze Data Some examples of data analysis include filtering scaling harmonic analysis or level checking Some data analysis tools are located on the Functions Signal Analysis subpalette and on the Functions All Functions Analyze subpalette SCXI 1125 User Manual 5 10 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 us
47. e 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 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 All Functions NI Measurements DAQm x Data Acquisition and select DAQm x 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 3 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 Instrument
48. easurement 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 look through the software documentation before you configure the hardware 1 3 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 e One or more of the following help files for software information Start All Programs National Instruments NI DAQ NI DAQm x Help Start All Programs National Instruments NI DAQ Traditional NI DAQ User Manual Start All Programs National Instruments NI DAQ Traditional NI DAQ Function Reference Help e NI application notes or tutorials NI has additional material about measurements available at ni com support You can download NI documents from ni com manuals To download the latest version of NI DAQ click Download Software Drivers and Updates at ni com Installing Application Software NI DAQ and the DAQ Device Refer to the DAQ Getting Started guides 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 DAQmx 9 0 or later is required to configure and program the SCXI 1125 module If you do not have NI DAQm x 9 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 c
49. ee 0 to 50 C Storage temperature 0 eee 20 to 70 C Humidity sect sscsetive actions teaserseecegranasaaliees 10 to 90 RH noncondensing Maximum altitude 2 000 meters Pollution Degree indoor use only 2 A 8 ni com Appendix A Specifications Safety This product meets 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 UL 61010 1 CSA 61010 1 3 Note For UL and other safety certifications refer to the product label or the Online Product Certification section Electromagnetic Compatibility This product meets the requirements of the following EMC standards for electrical equipment for measurement control and laboratory use e EN 61326 IEC 61326 Class A emissions Basic immunity e EN 55011 CISPR 11 Group 1 Class A emissions e AS NZS CISPR 11 Group 1 Class A emissions e FCC 47 CFR Part 15B Class A emissions e ICES 001 Class A emissions 3 Note For the standards applied to assess the EMC of this product refer to the Online Product Certification section 3 Note For EMC compliance operate this device with shielded cables CE Compliance C This product meets the essential requirements of applicable European Directives as follows e 2006 95 EC Low Voltage Directive safety e 2004 108 EC Electromagnetic Compatibility Directive EMC Online Product Certification Refer to the product Decla
50. eeescssecsseeeteceseeesneceaeeceaeeeeeeeaeeeaeeeseessaee Configuring Module Property Pages in Traditional NI DAQ Legacy 0 ceeeesseeseceseeceteeeeeeeeeeeseeeneeeees Creating a Virtual Channel eee eeceeeeeceecesecneeeseeeeetaeeeaees Verifying the Sigma cisci is ceeicis Sevtev ios aa ede sist alain teeta leads KNE Verifying the Signal in NI DAQmx Using a Task or Global Channel Verifying the Signal in Traditional NI DAQ Legacy eee eee eeeeeeeeeeees Verifying the Signal Using Channel Strings seese Verifying the Signal Using Virtual Channel 0 0 0 Chapter 4 Theory of Operation Filter Bandwidth and Cutoff Frequency 0 eee ec eeecesesseceeeseceseeecseecseeeaeensenseeaeeeaes Operating in Multiplexed Mode o00 eeeecceeeseceeceseeeeeeseceeeeecseseaeseeseaeseeesesseeeaeesaees Multiplexed Hardware Operation Theory cceceseeseesceseeseeeseeneeeseeeeeaes Operating in Parallel Mode naiinis eiiean aa leet cba E RTS Theory of Parallel Hardware Operation sesesessereeesseereesreresresesresrsersrrsresrse Chapter 5 Using the SCXI 1125 Temperature Measurements Using Thermocouples 0 0 0 0 eceeeeeeseesceseeeeeeseeeeeeseeeees Making High Voltage Measurements 00 cece eeceeeeeeeesececeseeseceseeseeeeeeeeaecaeseaeeaeenaes Developing Your Application in NI DAQMX e cei eeeeeseceseeeseceeeceaeeeeeceeeesneeeaeerses Typical Program Flowchatt 0 ice eeeeseessceecesseseesseeesecseesseeseesseeeeeae
51. els 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 repeatedly 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 y Configure Acquisition Settings y Configure Mode Properties Create Virtual Channel in MAX Start Acquisition Take Measurements Continue Sampling Scale Analyze and Display 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
52. ensseaeenes SCXI 1125 User Manual vi ni com Contents General Discussion of Typical Flowchart 00 cece eeeceseeeeeeeeseeeseeeseeeeees 5 7 Creating a Task Using DAQ Assistant or Programmatically 5 7 Adjusting Timing and Triggering oe eee eeeeeeneeeeeeeeeseeeees 5 7 Configuring Channel Properties cee eeceeecsceeseeeeecseeeseeeeees 5 8 Acquiring Analyzing and Presenting cee eseeeeeeeseereeeeeeees 5 9 Completing the Application 0 0 ee eeseeeesecseeeseeeeeeeeceeeeseseeeeaees 5 9 Developing an Application Using LabVIEW eceeeeseesseeseeeeeeeeneeeaes 5 9 Using a DAQmx Channel Property Node in LabVIEW 5 11 Specifying Channel Strings in NI DAQMX eee cece ceeeeeeseeeseeseeeaeens 5 12 Text Based ADES iiss 2ise bseetisssscusteasecibasbiescoassecdoestesetasescapbedisedveouaees 5 14 Measurement Studio Visual Basic NET and C cccccessccessseeseteeeseees 5 14 Programmable NI DAQmx Properties cceseeseeseeeeseeeeeeeeeeees 5 14 Developing Your Application in Traditional NI DAQ Legacy cece eeeeeeeeeees 5 15 Traditional NI DAQ Legacy in LabVIEW 1 0 0 ec ceeeeseceseeeseeceeeeeeeeeeeeeaees 5 16 Typical Program FLOW siccis cesscseceseeseeeseeseeeeeeeeenecseeeateaeeeseesaes 5 17 Configure the SCXI 1125 Settings Using Traditional NI DAQ Legacy in LabVIEW mei eni earair i aera TEA onder ee savage ter E N aed csseaveys 5 18 Configure Start Acquisition and Take Re
53. entation 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 computer environment The analog bus where SCXI 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 Vims W working isolation working voltage SCXI
54. eration 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 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 National Instruments Corporation 4 3 SCXI 1125 User Manual Chapter 4 Theory of Operation 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 X Series DAQ device The CJC channel is not accessible Every SCXI 1125 configured for parallel mode must have a E M X Series DAQ device directly cabled to it ys Note You can also use the SCXI 1125 with an S Series DAQ device in parallel mode Theory of Parallel Hardware Operation SCXI 1125 User Manual In parallel mode the CH 0 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 de
55. erter 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 line 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
56. erves 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 s modifi
57. es of the two modules Other specifications and features of the SCXI 1125 are the same 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 8 8 Input range 5 V 250 V with SCXI 1327 5 V 300 V with SCXI 1327 1000 VDC with TBX 1316 Isolation 250 Vins 300 Vms 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 M TEMP CJ TEMP scannable D TEMP direct channel 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
58. esrrresresrsereresre A 8 Table D 1 Comparison of the SCXI 1125 with the SCXI 1120 we D 1 Table D 2 Digital Signals on the SCXI 1125 woos ceeeeeneeeseeseeeseeeees 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 a jumperless eight channel isolated analog input conditioning module with programmable gain and filter settings on each channel 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 Vms 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 CXI 1305 e SCXI 1313A e SCXI 1320 e CXI 1327 e SCXI 1328 e SCXI 1338 e TBX 1316 e TBX 1328 e TBX 1329 Nationa
59. f 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 gradient 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 Legac
60. filenames and extensions Italic text in this font denotes text 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 o scvatisviie dk EE cenit ee eres be Atenas EERE 1 1 National Instruments Documentation 0 tees eeeeeeceseceeeeseeseeeseeseeeseceensesneeeaeensenaes 1 3 Installing Application Software NI DAQ and the DAQ Device 0 0 eee 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 X Series DAQ Device for Multiplexed Scanning 0 0 ee ceeeee eee eeeereeeeeseeneeeaes 1 4 Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M X Series DAQ Device for Multiplexed Scanning 00 0 eee 1 5 Connecting the SCXI 1125 to an E M X Series DAQ Device for Parallel Scanning soncde sie ieiiad wake aida hain nei 1 5 Verifying the SCXI 1125 Installation in Software eeeeeeeeeeeeeeeeeeneeeseeeeeeeeeees 1 6 Installing SCXI Using NI DAQmx in Software occ esses eects eeeeeeees 1 6 Manually Adding Modules in NI DAQMX 0 00 eee eeseeseeeeeteeeneeteeeenees 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 eee ee eeeeeeeeeeeeeenseeeees 1 6 Troubleshooting the Self Test Verification cece ei eeceesecscceeeeseessee
61. ges 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 Chapter 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 acq
62. ght 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 The 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 e _ A B C 30 AIl AIl 32 o o 29 E _ 31 28 NC NC 30 o o 29 _ a 28 o o 26 AI2 AI2 27 25 2 _ ce leg a 24 AI3 AI3 25 24 o o 23 _ _ 23 22 NC NC 22 o o 21 Pen 21 20 Al4 AI4 20 o o 19 19 18 a 5 18 AI5 AI5 17 17
63. gnal SCXI 1125 User Manual 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 noise that can be 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 UN Caution 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
64. hange 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 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 DAQmxSetChanAt tribute function 3 Note Refer to the LabWindow
65. he 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 over 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 c
66. he SCXI chassis and or SCXI module s should now be removed from the list of installed 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 a 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 M X 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 featur
67. how do I get the most current version of NI DAQ You must have NI DAQm x 9 0 or later 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 contact an NI technical support representative Refer to the Technical Support Information document for more information 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 X 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 X Series DAQ device all E M X Series DAQ channels are unusable for general purpose analog
68. ils on SCXI scanning SCXI 1125 User Manual D 4 ni com Glossary Symbol Prefix Value p pico 10 2 n nano 10 9 u micro 10 6 m milli 10 3 k kilo 103 M mega 106 G giga 10 T tera 10 Numbers Symbols 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 AID 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
69. ing 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 you 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
70. input If you have a module in the chassis that does not have parallel mode connect the E M X Series DAQ device to it and use a breakout connector to connect to the unused channels on the E M X Series DAQ device If you are directly connected to a higher input channel device such as a 64 channel 32 differential inputs E M X Series DAQ device only the lower eight differential inputs are unusable Which digital lines are unavailable on the E M X 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 X 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 PO 1 DAQ D A 27 17 Output DIO2 PO 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
71. itional 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 National Instruments Corporation 5 23 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 acquisition 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 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 t
72. l Instruments Corporation 1 1 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 B 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 X Series multifunction DAQ device e SCXI 1600 module ay Note You can also use the SCXI 1125 with an S Series simultaneous sampling DAQ device but only in parallel mode A computer if using an SCXI chassis Cabling cable adapter and sensors as required for your application QO Software NI DAQmx 9 0 or later One of the following software packages e LabVIEW e LabWindows CVI e Measurement Studio Q Documentation Read Me First Safety and Electromagnetic Compatibility DAQ Getting Started guides SCXI Quick Start Guide SCXI 1125 User Manual Documentation for your hardware Documentation for your software SCXI 1125 User Manual 1 2 ni com Chapter 1 About the SCXI 1125 National Instruments Documentation 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 National Instruments Corporation SCXI chassis or PXI SCXI combination chassis manual Read this manual for maintenance information about the chassis and for
73. lectrical characteristics most often voltage resistance and current electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed electromechanical compliance electromagnetic interference G 4 ni com F filtering FSR G gain gain accuracy gain error GND I 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 me
74. 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 e 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 Gain Range V 1 5 2 2 5 5 1 10 0 5 20 0 25 50 0 125 100 0 05 200 0 025 250 0 020 500 0 010 National Instruments Corporation 5 31 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Table 5 9 Gain Values and Input Limits Continued Gain Range V 1000 0 005 2000 0 0025 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 En
75. ltering 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 Systems 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
76. n 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 National Instruments Corporation 5 5 SCXI 1125 User Manual Chapter 5 Using the SCXI 1125 Yes No Create Task Using DAQ Assistant y y Create a Task Programmatically Create Task in DAQ Assistant or MAX Create Another Create Channel Application Specific Channel Hardware Timing Triggering Further Configure Channels Adjust Timing Settings Configure Channels Start Measurement Process Data Yes Display Data Graphical Read Measurement Display Tools A Yes Continue Sampling Stop Measurement y Clear Task 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
77. n and Range Using the SCXI 1327 or SCXI 1313A Overall Input SCXI 1125 SCXI 1327 SCXI 1313A Gain Range V Gain Attenuation Attenuation 0 01 300 1 100 0 02 250 2 100 0 002 150 2 100 100 0 05 100 5 100 100 0 1 50 10 100 100 0 2 25 20 100 100 0 5 10 50 100 100 2 5 2 250 100 100 5 4 ni com Chapter 5 Using the SCXI 1125 Table 5 2 Extended Gain and Range Using the TBX 1316 Overall Input Range SCXI 1125 TBX 1316 Gain V Gain Attenuation 0 005 1000 1 200 0 01 500 2 200 0 025 200 5 200 0 05 100 10 200 0 1 50 20 200 0 25 20 50 200 1 25 4 250 200 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 i
78. nel you can only select one channel Click Next 7 Name the task or channel and click Finish 8 Inthe 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 key 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 about using functions in your application Most of these settings are available in module
79. nel Property Node with Lowpass Frequency Set at 10 kHz on Channel SC1Mod1 ai0 sssesesseseeeeseeeseesrsrrsrrerserersse 5 12 Typical SCXI 1125 Program Flow with Traditional NI DAQ Legacy ceseesscsseeeseeeeteeeseeeseeceaeeeteeeenees 5 17 Using the AI Parameter VI to Set Up the SCXI 1125 wo 5 19 SCXI 1125 Dimensions isinisi ra niae spisas isai A 7 Removing the SCXI 1V 25 nenon t aa aa koir C 2 viii ni com Contents Tables Table 2 1 Front Signal Pin Assignments 00 0 eee eeeeeeceeeeseeseeneeeseseesseeeeees 2 6 Table 2 2 Rear Signal Pin Assignment 0 sceeeseeseeeeceseeeeeseeaeeneeeseensesseeenees 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 oo eee 5 5 Table 5 3 NI DAQmx Propertie Srp a e e a 5 8 Table 5 4 Programming a Task in LabVIEW eee cesses ceseeeseeeeseeeeseeneeenees 5 10 Table 5 5 NI DAQmx Properties 2 0 eee ec aa E e a AE E 5 15 Table 5 6 Settings for Configuring the SCXI 1125 Through the AI Parameter eee nanio aera 5 18 Table 5 7 Configuration FUNCtions niare pe a ere EE ras 5 22 Table 5 8 NI DAQ Functions Used to Configure SCXI 1125 oe 5 23 Table 5 9 Gain Values and Input Limits oo eee eee ceeceeecneeeeeeseeneeeseeeeens 5 31 Table A 1 Input Signal Range Versus Gain oo eee eee ceeeeeeeeeeeeeeeneeaeeeseeaeees A 1 Table A 2 Terminal Block Maximum Voltages sseeeseeseeeseeresrer
80. nstruments Corporation A 1 SCXI 1125 User Manual Appendix A Specifications Overvoltage protection Isolated connector pins Powered on and Off ees eeeeeeeeees 300 V Inputs protected eee eeee CHO CH7 Non isolated connector pins Powered on and Off ce eeeeeeeeeeee 5 5V 0 5 V SCXI 1125 User Manual A 2 ni com Specifications Appendix A vL0 0 6r10 0 L000 0 6TS ooze ooz oz 000S 0001 S00 0 ITTO 8TTO 0 100 0 167 ooze ooz oz 000S 00s 10 0 vITO TLE0 O ET00 0 ELI oore ooz oz 000S OST TO OF TOTO 6L70 0 97000 8rl oore 007 oz 000S 007 STO OF S6v 0 7880 0 7900 0 oor oore 007 SI 000S oor SO OF L960 OSTO 1100 LL oore 007 SI 000S os TOF 6ET vLyv0 c 0 0 9 oore ooz SI 000S oz STOF vEt T880 690 0 8s oore ooz SI 000S Or S OF 9 6 Li OTTO 8S oorte ooz SI 000S S I ESET Cv S70 SS oore 007 I 000S T CCF C8 9r 9 8 ESO vs oore 007 Ol 000S I SF OVO Vol I LL oore 007 ce O0Ss S O LO1 8 SST 8r 9 oorte ooz TE 00SS TO LSTF STIS IIT 9 8S oore ooz oe 00SS To LOS S TOI EST TI 8S oore ooz oe 00Ss S00 LOO1 LIST 84t oe SS oore 007 87 o0ss ToO LOSTF SY99STI oZ91 SII vs oore 007 07 OOcIT 00 0 9000 1 AUN ZH OT ZHY 9 esuey qjuourjasuey aduey jo 9 surpeay surpeoy ueg A esuey I VI MA Jo wdd jo wdd auqa wdd 10114 Jo wdd jo wdd 1121240 eurWION qe AWIMIV lod BUS ooduraq IL PSYO PSO ooduray lori ures aynjosqy PSO Tenprsoy u
81. nt for contact information 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 connectors 3 Note Refer to the Read Me First Safety and Electromagnetic Compatibility document before removing equipment covers or connecting or disconnecting any signal wires ny Note For EMC compliance operate this device with shielded cables The isolated channels of the SCXI 1125 allow you to make precision high voltage measurements or low voltage measurement of signals where high common mode voltages are present 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 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 X 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
82. nts Alliance Partner Program are business entities independent from National Instruments and have no agency partnership or joint venture relationship with National Instruments Patents For patents covering National Instruments products technology refer to the appropriate location Help Patents in your software the patents txt file on your media or the National Instruments Patent Notice at 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
83. ny 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 Traditional NI DAQ User Manual for additional information about 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 about 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 about 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 about 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 T
84. o Chapter 3 Configuring and Testing for troubleshooting steps Troubleshooting the Self Test Verification If the Self Test Verification did not verify the chassis configuration complete the steps in this section to troubleshoot the SCXI configuration Troubleshooting in NI DAQmx National Instruments Corporation If you get a Verify SCXI Chassis message box 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 Make sure the SCXI chassis is powered on Make sure all SCXI modules are properly installed in the chassis Refer to the SCXT Quick Start Guide for proper installation instructions Make sure the cable between the SCXI chassis and E M X 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 X Series DAQ device to verify it is working properly Refer to the E M X 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 DAQmx devices by clicking
85. o the Traditional NI DAQ Legacy Function Reference Help installed by default in Start All 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 constants 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 All 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 way
86. om 3 Note Refer to the Read Me First Safety and Electromagnetic Compatibility document before removing equipment covers or connecting or disconnecting any signal wires Installing the SCXI 1125 Module into the SCXI Chassis Refer to the SCXT Quick Start Guide to install your SCXI 1125 module Connecting the SCXI 1125 in an SCXI Chassis to an E M X Series DAQ Device for Multiplexed Scanning SCXI 1125 User Manual 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 1 4 ni com Chapter 1 About the SCXI 1125 Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M X 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 Connecting the SCXI 1125 to an E M X 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 X 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 SCXI system in multiplexed mode allow
87. on and click Next Enter the following information a What DAQ hardware will be used from the drop down list b What channel on your DAQ hardware from the drop down list c Which analog input mode will be used from the drop down list 10 Click Finish Verifying the Signal This section describes how to take measurements using test panels in order 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 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 3 6 ni com Chapter 3 Configuring and Testing 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 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
88. one 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 Accessory 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 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 SO GO Oy ie Bi Ge he Ea 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 opti
89. orresponds 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 terminal 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 V 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 SCXI 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 Gai
90. 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 configuration 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 5 28 ni com Chapter 5 Using the SCXI 1125 operating mode using MAX as described in Chapter 1 About 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 a
91. pass Lowpass 8 F Filter gt Fiter 2 Al 7 a l L y MTEMP Digital Interface D 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 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 fi
92. plexed 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 channel string calgnd channel string D 3 SCXI 5 25 virtual 5 26 National Instruments Corporation channels C language scanning D 4 questions about D 3 unused analog input channels on DAQ device D 2 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 to SCXI 1125 for multiplexed scanning in PXI combination chassis 1 5 3 2 in SCXI chassis 1 4 3 2 connecting with SCXI 1125 for parallel scanning 1 5 unavailable digital lines D 2 unused analog input channels D 2 l 1 SCXI 1125 User Manual Index DC voltage connections See AC and DC voltage connections digital lines unavailability on DAQ device D 2 digital signals on SCXI 1125 table D 3 documentation conventions used in the manual iv E environmental specifications A 8 F filter setting changing D 4 filters ban
93. 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 properties When you set the minimum and maximum range of the virtual channel the driver selects the best gain The default gain setting for Traditional NI DAQ Legacy is 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 3 Note Refer to Chapter 4 Theory of Operation for information about 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 N
94. ration of Conformity DoC for additional regulatory compliance information To obtain product certifications and 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 NI is committed to designing and manufacturing products in an environmentally responsible manner NI recognizes that eliminating certain hazardous substances from our products is beneficial to the environment and to NI customers For additional environmental information refer to the NJ and the Environment Web page at ni com environment This page contains the environmental regulations and directives with which NI complies as well as other environmental information not included in this document Waste Electrical and Electronic Equipment WEEE EU Customers At the end of the product life cycle all products must be sent to a WEEE recycling center For more information about WEEE recycling centers National Instruments WEEE initiatives and compliance with WEEE Directive 2002 96 EC on Waste Electrical and Electronic Equipment visit ni com environment weee Dx EFAA mis Rib SIME CHE ROHS QL FERA National instruments 414 Ea TAS AP i t RENEA 3AA ROHS XF National Instruments FE ROHS AWISE tS ni com environment rohs_china For information about Chin
95. rement Type AI MeasType Indicates the measurement to take with the analog input channel 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 For a complete list of NI DAQmx properties and more information about NI DAQmx properties refer to your ADE help file Developing Your Application in Traditional NI DAQ Legacy Ai 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 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
96. res Tenpisoy CTAW LOF ISON Aseinaoy aynjosqy SCXI 1125 User Manual A 3 National Instruments Corporation Specifications Appendix A YOorq BUTTON a8ejTOA YSIY LZET IXOS OU WIM 1 YOO eUu 9304 431 OTE T K EL OU PIM 9 AU g 9p AownsoVyonjosqy AyureVooUaSION JOLIGIOSO x A S Gourgue x A AovInsoyanjosqy 91 AM OSIZ AqureyooupasIoN Ai 0008 AjuIe IONU9SION wdd 0pg 1oLMEsyYO OL x wdd p x wdd gore wdd 007 JoUMsSYO wdd 0015 Jomquieyn OL x wdd go wdd 0005 Jouquiey ISMOT OJ SB ST LIS PN ye LL oINTOSge oy oSuRI A GF OY UO a dtuexXa 104 puou UOL LIJ SINJV oul 9 SOBRIOAVJOIOQUINN Do SE 0 Do SI o8uey amprdwaL suondunsse SUIMOT OJ OY SUISN PoUTWUJoJap SI AVIS NJ W Lw nIw Amjosqy sodevIoayjOIoquinn SSION AjureyO0UasIoN eQeusaupseJworjosueygdwayp x oodwapiasjjO UONIGIEOJPOSIAJYVOWLL X YUCSwWLLIes O JOLUMIsJOenpisoy JOLUAIsSO eQeusoyxqse TwoLjosueypdwuay x oodwiapurey Jouquieolenpisoy Joquiey A UILJIDOU SION JOLIGIOSYO x osuey JOLIquIeH x Sulpesy Aovinooyoinjosqy W 1 21989 qA 89 89HS OU WIM FOE09 IXd amp SUISA p wdd 6 L01 PUAA 110SO TIM X YUAUMOW TSO YUCIeIA PSO og wdd 99 yuqleqr syo Juano yuqdeq SHO puou JO ILIP ouy Jaso oy Sursn paeme oq uvo reaX pue Aep JO YLIp IWUN PSO oy FULI A CF IP UO Ijdwex 104 ONLI SLUT I JO JOOI areNbs IY Aq PALIS oq UL
97. ries DAQ device If the module is directly connected to the E M X Series DAQ device the other analog channels of the E M X 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 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 X 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 CH1 5 6 CH 1 2g CH2 7 8 CH2 7 8 9 10 CH3 9 10 CH 3 Vee
98. rted on all SCXI modules Please refer to the manual of each module for information about 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 linearization 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 about virtual channels
99. s 3 Note You can also use the SCXI 1125 with an S Series DAQ device in parallel mode 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 National Instruments Corporation Power off the SCXI chassis and the computer that contains the E M X Series DAQ device Insert the cable adapter into the rear of the SCXI 1125 module that is to be accessed in parallel mode by the E M X Series DAQ device Refer to the installation guide for the cable assembly for more information Connect the cable to the back of the cable adapter ensuring that the cable fits securely Connect the other end of the cable to the E M X Series DAQ device that you want to use to access the SCXI 1125 in parallel mode Connect additional SCXI 1125 modules intended for parallel mode operation by repeating steps 2 through 4 Check the installation making sure the cable is securely fastened at both ends Power on the SCXI chassis Power on the computer 1 5 SCXI 1125 User Manual Chapter 1 About the SCXI 1125 If you have already installed the appropriate software you are ready to configure the SCXI 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 about verifying the SCXI installation Installing SCXI Using NI DAQm x in Softw
100. s Minimum eee eee eereete etree 0 1 V s Scan interval accuracy LOS aa h Steeevedvadeces metered 3 us HONS TOs aa de eats 10 us HO O06 Moeessiesisccisibsadvs cdasies Sea cis bees 28 us 0 0015 isiin ias 32 us 1 Using a PXI 6251 with the SHC68 68 EPM cable 1 m National Instruments Corporation A 5 SCXI 1125 User Manual Appendix A Specifications Common mode rejection ratio 50 60 Hz CMRR 4 Hz filter enabled 160 dB 10kHz filter enabled 0 98 dB Crosstalk at 1kHz Adjacent channels All other channels Input coupling Default Using SCXI 1305 or TBX 1329 Power Consumption Output Characteristics O tp t TAN GE ease Output impedance Multiplexed output mode Parallel output mode Transfer Characteristics Nonlinearity Allan es nia Stability Recommended warm up time ONSEt drifta etal ee teete Sites lesen iad Gain Atiftis ice ecesiaciiiainiivie siecle amp SCXI 1125 User Manual A 6 75 dB 90 dB DC AC or DC 140 mA max 140 mA max 10 mA max 5 0 V 100 Q 330 Q 0 02 of full scale range 15 minutes 0 42 250 gain pV C 20 ppm C typical ni com Appendix A Specifications Calibration External calibration interval 1 year Physical 3 0 cm 1 2 in o WI A EH B e pee 17 2 cm B 6 8 in o i o M gH 18 8 cm E 7 4 in Fig
101. s 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 nidagex 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 software 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 about programming the SCXI modules for scanning in multiplexed mode LabVIEW and the SCXI Channel String For LabVIEW and Visual Basic
102. s CVI Help for more information about 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 1125 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 DAQm x 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 Measu
103. s 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 f DAQmx Channel 8 ActiveChans bAT Lowpass CutoffFreq SC1Mod1 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 5B 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
104. 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 subpalette 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 gau
105. seeseeeseeneeeaeeneeaes 1 7 Troubleshooting in NI DAQMX 2 0 0 eeeeeeceeeseeeseeceseeeeeceaecseeeeaeeeaeeceeeseneeesaes 1 7 Chapter 2 Connecting Signals AG and DC Voltage Connections sessist specs eens srein eR a RERA RE EERE ES 2 1 Ground Referenced Signal ssiri ae a arr aian ian 2 2 Floating Signal ssineee ereer a E E E T E E 2 3 AC Coupling erni an dig ier ate ee Ran E ERS 2 4 Pan ASSLEMIMEDUS 3 orth So Sec cs Sesce ets e EEE AEEA E EE 2 5 Temperature Sensor Connection 0 cece eeceeeeeseeseeeeeeseeseeeseessenseeeeeeeseeaes 2 7 Rear Signal Connectors Mask cvves r aa tive Ei a T AAST 2 7 National Instruments Corporation v SCXI 1125 User Manual Contents Chapter 3 Configuring and Testing SCXI 1125 Software Configurable Settings 0 0 eee ee cee ceeeesececeesecseeeseeneeseeseeesees Common Software Configurable Settings cece cece seeeseeseceeceeetseeseeesees Filter Bandwidth s s soccs5 sceccasscscsassssgedssss asgscbdescebascapeedvbestedaccosdseheaseese Gain Input Range esiones Connecting the SCXI 1125 in an SCXI Chassis to an E M X Series DAQ Device for Multiplexed Scanning sseeseeeeesreerssreresrsresrerrsresreseses Connecting the SCXI 1125 in a PXI SCXI Combination Chassis to an E M X Series DAQ Device for Multiplexed Scanning eee Configurable Settings In MAX cererii sistini ai aiaa EDIO ntb EEE E EE E A EE T Creating a Voltage Global Channel or Task eee eee Traditional NI DAQ Legacy 0 ece
106. 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 a TONE ee Oa Refer to the LabVIEW Help for more information and for 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 H Fiter gt Filter on R AlO 5 l y Analog D Multiplexer z AI7 fo m gt 2 TE i gt z A 5 8 Scan d o m oc e 13a Clock c e 2D To 5 Analog ic Gain Select Multiplexer Analog Bus gt g Control Bus 2 Cc Low
107. ter 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 must use an external reference to perform a two point calibration Refer to the SCXI 1125 Calibration Procedure document for more information about doing an external two point gain and offset calibration SCXI 1125 User Manual 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 VDC 2 5 1 Vpeak Or VDC 5 10 500 MV peak Or VDC 10 20 250 MV peak Or WDC 20 50 100 MV pa or WDC 50 100 50 MV peak or VDC 100 200 25 MV peak Or WDC 200 250 20 MV peak Or WDC 250 500 10 MVpeax Or VDC 500 1000 5 MV eax 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 I
108. tts 5 29 Other Application Documentation and Material eee eee eseeeeeeseeeeeeseeeseeaeeneeeaes 5 29 Traditional NI DAQ Legacy CVI Examples eee eeseesceesseeesereeeeeees 5 29 Traditional NI DAQ Legacy Measurement Studio Examples 0 0 5 29 Calibration sssini an a E R AEA T A a a 5 30 Calibration Procedures soinen niea naana aiai 5 30 One Point Offset Calibration ssssseesseeeseeseesesrsrrsrsrrsrsrrereresresrssee 5 31 Two Point Gain and Offset Calibration sseeeeeeeesseeseeerreeeererreree 5 32 National Instruments Corporation vii 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 ec eeeeeseeeeeeeeeneees 2 2 Connecting a Floating Signal eee eeeeseeseeeseeseeeaeeeseeaeeeeeeaeens 2 3 Connecting a Floating AC Coupled Signal 0 eee eee eeee 2 4 Connecting a Ground Referenced AC Coupled Signal 2 4 SCXI 1125 Block Diagram ieee eeeseeesececceseceseeeeesesseeeaeeeeeeneees 4 1 Typical Program Flowchart seeeessseesseeeseesseessrseseesrestsresrsrrsresresesreseeee 5 6 LabVIEW Chan
109. u 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 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 Electromagnetic Compatibility 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
110. uisition 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 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 All 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 ar
111. uracies 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 its 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 Examples are E M X Series DAQ devices and the SCXI 1600 module decibel The unit for expressing a logarithmic measure of the ratio of two signal levels dB 20 logio 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 e
112. ure A 1 SCXI 1125 Dimensions Welghtairninnnsne a 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 00 0 eee eeeeeeereees 300 V Measurement Category II Channel to chanmel eee 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 Caution 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 00 0
113. vice 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 X Series DAQ device you connect to the module 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 about 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 o
114. wpass 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 X Series DAQ device In most applications NI DAQ chooses and sets the gain for you determined by the input range 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 X 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 X 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 inst
115. y 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 this 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 re

SCXI-1125 User Manual - National Instruments

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