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National Instruments Module SCXI-1503 User's Manual

1. gt 1 GQ Input bias current sees 2 8 nA 1 Assumes 1 000 point average 25 C 10 C over one year Assumes 1 000 point average 1 C of autozero temperature SCXI 1503 User Manual A 2 ni com Appendix A Specifications CMRR characteristics DC to 60 Hz Calais 75 dB min 90 dB typ Gam OOM ee teneis 106 dB min 110 dB typ Output range nece 10 V Output impedance sess 91 0 Dynamic Characteristics Minimum scan interval per channel any gain 0 012 accuracy eee eee 3 us 0 0061 accuracy 10 us 0 0015 accuracy 20 us Noise characteristics RTI Gain 1 10 Hz to 1 MHZ ou eee 100 LV ins Gain 100 10 Hz to I MHZ eee 1 UVims 0 dito I0 MZ int 0 5 LV Filter Cutoff frequency 3 dB 5Hz NMR 60 Hz A i 40 dB min Step response characteristics gain 1 or 100 To 0 0015496 iia iaa 0 6 s Stability Recommended warm up time 20 min Offset temperature coefficient Gams T uen S 35 u VC max 10 uV C typ Gams lus 1 5 uV C max 0 5 uV C typ National Instruments Corporation A 3 SCXI 1503 User Manual Appendix A Specifications Gain temperature coefficient gain 1 or 100 ineine 15 ppm C max 5 ppm C typ Excitation Channels scm cali a 16 single ended outputs Current output resiente 1
2. 4 11 Figure 4 5 Thermistor Measurement with Constant Current Excitation 4 11 Figure 5 1 Typical Program Flowchart for Voltage Measurement Channels 5 2 Figure A 1 SCXI 1503 Dimensions eaei sira enne A 5 Figure B 1 Removing the SCXI 1503 ssssssmssrsrsrrsresrsresresrsrsesresrsrersrsresrernrsrerrrrernrrrrn rna B 2 National Instruments Corporation vii SCXI 1503 User Manual Contents Tables Table 1 1 Supported SCXI 1503 Terminal Blocks eseeeess 1 4 Table 2 1 Front Signal Pin Assignments esee 2 8 Table 2 2 Signal Descriptions ettet ru D Re sevens cdas 2 9 Table 2 3 Rear Signal Pin Assignments s sssssssrssrsrrsrerrsresrsresresrsresrsrrsrrrrrr ennen rn rrn rna 2 10 Table 2 4 SCXI 1503 50 Pin Rear Connector Signals sess 2 11 Table 4 1 Platinum RTD Types 2 rte retener 4 8 Table 5 1 NI DAQmx Voltage Measurement Properties sess 5 4 Table 5 2 NI DAQmx RTD Measurement Properties sse 5 5 Table 5 3 NI DAQmx Thermistor Measurement Properties se 5 6 Table 5 4 NI DAQmx Thermocouple Measurement Properties 5 7 Table 5 5 Programming a Task in LabVIEW see 5 8 Table A 1 RTD Measurement Accuracy seesseeseeeeeeeeeennee nee A 2 SCXI 1503 User Manual viii ni com About the SCXI 1503 This
3. Adjust Timing Settings Configure Channels Start Measurement Read Measurement Yes A Process Data nalyze Data ues Display Data Display Tools Yes Continue Sampling Y Stop Measurement Clear Task Figure 5 1 Typical Program Flowchart for Voltage Measurement Channels SCXI 1503 User Manual 5 2 ni com Chapter 5 Using the SCXI 1503 General Discussion of Typical Flowchart The following sections briefly discuss some considerations for a few of the steps in Figure 5 1 These sections are meant to give an overview of some of the options and features available when programming with NI DAQmx Creating a Task Using DAQ Assistant or Programmatically When creating an application you must first 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 tas
4. master in slave out signal master out slave in signal to route one of many input signals to a single output an SCXI operating mode in which analog input channels are multiplexed into one module output so that the cabled E M Series DAQ device has access to the multiplexed output of the module as well as the outputs of all other multiplexed modules in the chassis not connected signal the driver software needed in order to use National Instruments E M Series DAQ devices and SCXI components The latest NI DAQ driver with new VIs functions and development tools for controlling measurement devices G 4 ni com 0 output voltage compliance OUT REF P ppm PXI RMA RSVD RTD scan SCAN CLK SCXI SCXIbus O National Instruments Corporation G 5 Glossary the largest voltage that can be generated across the output of a current source without the current going out of specification output reference signal parts per million PCI eXtensions for Instrumentation an open specification that builds on the CompactPCI specification by adding instrumentation specific features lead resistance Return Material Authorization reserved bit pin or signal resistance temperature detector seconds samples one or more analog samples taken at the same time or nearly the same time Typically the number of input samples in a scan is equal to the number of channels in the input group For example one scan acquires on
5. 1503 are available in NI DAQmx 8 1 or later Refer to the NJ DAQmx Help for details about these functions Most external calibration documents for SCXI modules are available to download from ni com calibration by clicking Manual Calibration Procedures For external calibration of modules not listed there Basic Calibration Service or Detailed Calibration Service is recommended You can get information about both of these calibration services from ni com calibration NI recommends performing an external calibration once a year B Note Performing an external calibration of the SCXI 1503 permanently overwrites the factory calibration settings which impacts the accuracy of the inputs SCXI 1503 User Manual 5 14 ni com Specifications This appendix lists the specifications for the SCXI 1503 modules These specifications are typical at 25 C unless otherwise noted Analog Input Input Characteristics Number of channels 16 differential Input coupling eee DC Input signal ranges 100 mV gain 100 or 10 V gain 1 Input overvoltage protection Powered on sse 42 VDC Powered off sess 25 V Inputs protected AI 0 15 CJ sensor input protection x15 VDC powered on or off Transfer Characteristics NOnlinearity s ssssssssssssspssnornsenss rars rsse
6. 33 DIG GND D GND Digital ground these pins supply the reference for E M Series DAQ device digital signals and are connected to the module digital ground 25 SER DAT IN P0 0 Input Serial data in this signal taps into the SCXIbus MOSI line to send serial input data to a module or Slot 0 National Instruments Corporation SCXI 1503 User Manual Chapter 2 Connecting Signals Table 2 4 SCXI 1503 50 Pin Rear Connector Signals Continued Pin SCXI Signal Name NI DAQmx Device Signal Name Direction Description 26 SER DAT OU T P0 4 Output Serial data out this signal taps into the SCXIbus MISO line to accept serial output data from a module 27 DAQ D A P0 1 Input Board data address line this signal taps into the SCXIbus D A line to indicate to the module whether the incoming serial stream is data or address information 29 SLOT 0 SEL P0 2 Input Slot 0 select this signal taps into the SCXIbus INTR line to indicate whether the information on MOSI is being sent to a module or Slot 0 36 SCAN CLK AI HOLD COMP AI HOLD Input Scan clock a rising edge indicates to the scanned SCXI module that the E M Series DAQ device has taken a sample and causes the module to advance channels 37 SER CLK EXTSTROBE Input Serial clock this signal taps into the SCXIbus SPICLK line to clock th
7. DAQ device If the scanned SCXI 1503 module is not directly cabled to the 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 DAQ device through the AI 0 pin on its rear signal connector If the DAQ device scans the cabled module the module routes its input signals through the AI 0 pin on its rear signal connector to a single channel on the DAQ device Measuring Temperature with Resistive Transducers RTDs This section discusses RTDs and thermistors and describes accuracy considerations when connecting resistive transducers to the signal conditioning system A resistive temperature detector RTD is a temperature sensing device whose resistance increases with temperature An RTD consists of a wire coil or deposited film of pure metal RTDs are made of different metals and have different resistances but the most popular RTD is made of platinum and has a nominal resistance of 100 Q at 0 C RTDs are known for their excellent accuracy over a wide temperature range Some RTDs have accuracies as high as 0 01 Q 0 026 C at 0 C RTDs are also extremely stable devices Common industrial RTDs drift less than 0 1 C year and some models are stable to within 0 0025 C year RTDs are sometimes difficult to measure because they have relatively low nominal resistance commonly 100 2 that changes only
8. 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 5 10 ni com Chapter 5 Using the SCXI 1503 B Note Refer to the LabVIEW Help for information about property nodes and specific NI DAQmx properties Specifying Channel Strings in NI DAQmx Use the channel input of DAQmx Create Channel to specify the SCXI 1503 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 ai0 e multiple noncontinuous channels for example SC1Mod1 ai0 SC1Mod1 ai4 e multiple continuous channels for example SC1Mod1 ai0 4 channels 0 through 4 When you have a task containing SCXI 1503 channels you can set the properties of the channels programmatically using the DAQmx Channel Property Node Text Based ADEs You can use text based ADEs such as LabWindows CVI Measurement Studio Visual Basic 6 NET and C to create code for using the SCXI 1503 LabWindows CVI LabWindows CVI works with the DAQ Assistant in MAX to generate code for an voltage measurement 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
9. Van Dusen coefficients shown in Table 4 1 T is the temperature in C Table 4 1 lists the RTD types and their corresponding coefficients Table 4 1 Platinum RTD Types Temperature Coefficient of Resistance Typical Callendar Van Standard TCR PPM Ro Dusen Coefficient IEC 751 3851 100 A 3 9083 x 103 DIN 43760 1000 Q B B BS 1904 B2 5 775x10 ASTM E1137 C 24 183 x 1072 EN 60751 Low cost 3750 10000 A 3 81 x 102 yn a B 6 02 x 107 compliant C 6 0 x 10 12 JISC 1604 3916 1000 A 3 9739x 102 B 5 870 x 107 C 4 4x 10 2 US Industrial 3920 100Q A 3 9787 x 107 UM B 5 8686 x 1077 American C 2 4 167 x 10712 4 8 ni com Chapter 4 Theory of Operation Table 4 1 Platinum RTD Types Continued Temperature Coefficient of Resistance Typical Callendar Van Standard TCR PPM Ro Dusen Coefficient US Industrial 3911 100 Q A 3 9692 x 103 pana B 5 8495 x 1077 American C 4 233 x 10712 ITS 90 3928 100 Q A 3 9888 x 102 B 5 915 x 1077 C 3 85 x 10712 1 No standard Check TCR For temperatures above 0 C coefficient C equals 0 reducing this equation to a quadratic If you pass a known current Igy through the RTD and measure the output voltage developed across the RTD Vo you can solve for T as follows V R T Try 2 2 Vo 0 5 RA RA 4RoB Ro 7t E where Vo is the measured RTD voltage Igy is the excitation cu
10. e e ERR D eae Re LER DRE aetna ic 3 4 Verifying the Signal in NI DAQmx Using a Task or Global Channel 3 4 National Instruments Corporation V SCXI 1503 User Manual Contents Chapter 4 Theory of Operation Rear Signal Connector SCXIbus Connector and SCXIbus Interface 4 3 Digital Control Circuitry miii ntt E ER era c Pire 4 3 An log CIrCultty 1 22d e fret OM RS 4 3 Analog Input Channels 4 41 i prn tret etes 4 3 Operation of the Current Sources oooconccnocnnoncnnonononncononononnncononnnonncnn non nonn ron n cnc nano eene 4 4 Theory of Multiplexed OperatiON oconcnnnnncionnnonconanancnnonnnonnnnnncnncnn rennen 4 4 Measuring Temperature with Resistive Transducers seseseseeeeeee 4 5 RPDS eee ete te e nte er m e e 4 5 RTD Measurement Errors eese 4 6 The Relationship Between Resistance and Temperature in RTDs 4 6 Jh tmistots ii etae ih POE 4 10 Thermistor Measurement Circuits esee 4 11 Resistance Temperature Characteristic of Thermistors 4 12 Chapter 5 Using the SCXI 1503 Developing Your Application in NI DAQmx eene 5 1 Typical Program Flowchart essent nennen eene 5 1 General Discussion of Typical Flowchart eee 5 3 Creating a Task Using DAQ Assistant or Programmatically 5 3 Adjusting Timing and Triggering esee 5 3 Configuring C
11. graphical form or log it to a file NI ADEs provide easy to use tools for graphical display such as National Instruments Corporation 5 7 SCXI 1503 User Manual Chapter 5 Using the SCXI 1503 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 B 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 1503 If you need more information or for further instructions select Help VI Function amp How To Help from the LabVIEW menu bar 3 Note Except where otherwise stated the VIs in Table 5 5 are located on the Functions All Functions NI Measurements DAQmx Data Acquisition subpalette and accompanying subpalettes in LabVIEW Table 5 5 Programming a Task in LabVIEW Flowchart Step VI or Program Step Create Task in DAQ Assistant Create aDAQmx Task Name Control located on the C
12. 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 The DAQ Assistant creates the code for the task based on the parameters you define in MAX and the device defaults To change a property of the channel programmatically use the DAQmxSetChanAttribute function National Instruments Corporation 5 11 SCXI 1503 User Manual Chapter 5 Using the SCXI 1503 lay Note Refer to the NJ LabWindows CVI Help for more information on creating NI DAQmx tasks in LabWindows CVI and NI DAQmx property information Measurement Studio Visual Basic 6 NET and C When creating an voltage measurement task in Visual Basic 6 NET and CH 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 voltage measurement channel on the SCXI 1503 You can use the same functions for Visual Basic 6 NET and C The following text is a function prototype example void AIChannelCollection CreateVoltageChannel System String physicalChannelName System String nameToAssignChannel System Double minVal System Double maxVal To actually create and configure the channel you would enter something resembling the following example code Task myTask new NationalInstruments DAQmx Task myTaskName MyTask DAQmxCrea
13. or oil bath Typical dissipation constants range anywhere from less than 0 5 mW C for still air to 10 mW C or higher for a thermistor immersed in water A 2 252 Q thermistor powered by a 100 WA excitation current dissipates PR 100 pA x 2 252 Q 0 0225 mW If this thermistor has a dissipation constant of 10 mW C the thermistor self heats 0 00225 C so the self heating from the 100 uA source of the SCXI 1503 is negligible for most applications It is still important to carefully read self heating specifications of the thermistors Resistance Temperature Characteristic of Thermistors The resistance temperature behavior of thermistors is highly dependent upon the manufacturing process Therefore thermistor curves are not standardized to the extent that thermocouple or RTD curves are standardized Typically thermistor manufacturers supply the resistance versus temperature curves or tables for their particular devices You can however approximate the thermistor curve relatively accurately with the Steinhart Hart equation 1 AA O a b In R7 c In A 4 12 ni com Chapter 4 Theory of Operation where T K is the temperature in degrees Kelvin equal to T C 273 15 Rr is the resistance of the thermistor 8 b and c are coefficients obtained from the thermistor manufacturer or calculated from the resistance versus temperature curve National Instruments Corporation 4 13 SCXI 1503 User Manual Using th
14. shipped with the product for 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 hardware labels or an introduction to a key concept Italic text also denotes text that is a placeholder for a word or value that you must supply Text in this font denotes text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions Contents Chapter 1 About the SCXI 1503 What You Need to Get Started ieir endea eeds e tenete nennen 1 1 National Instruments Documentation esses rennen 1 2 Installing Application Software NI DAQ and the E M Series DAQ Device 1 4 Installing the SCXI 1503 Module into the SCXI Chassis 1 4 Installing the Terminal BICK iecere ienee ane a e i 1 4 Configuring the SCXI System Software oooooncnocnoon
15. slightly with temperature less than 0 4 Q C To accurately measure these small National Instruments Corporation 4 5 SCXI 1503 User Manual Chapter 4 Theory of Operation SCXI 1503 User Manual changes in resistance you must use special configurations that minimize measured errors caused by lead wire resistance RTD Measurement Errors Because the RTD is a resistive device you must pass a current through the device and monitor the resulting voltage However any resistance in the lead wires that connect the measurement system to the RTD adds error to the readings For example consider a 2 wire RTD element connected to a measurement system that also supplies a constant current Igy to excite the RTD As shown in Figure 4 2 the voltage drop across the lead resistances labeled R adds an error voltage to the measured voltage or RL e WWW 0 0 Ry 0 RL WWW Figure 4 2 2 Wire RTD Measurement For example a lead resistance of 0 3 Q in each wire adds a 0 6 Q error to the resistance measurement For a platinum RTD at 0 C with a 0 00385 the lead resistance equates to an error of approximately 0 6 Q 16 C 0 385 Q C Chapter 2 Connecting Signals describes different ways of connecting resistive devices to the SCXI system The Relationship Between Resistance and Temperature in RTDs Compared to other temperature measurement devices the output of an RTD is relatively linear w
16. the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation National Instruments respects the intellectual property of others and we ask our users to do the same NI software is protected by copyright and other intellectual property laws Where NI software may be used to reproduce software or other materials belonging to others you may use NI software only to reproduce materials that you may reproduce in accordance with the terms of any applicable license or other legal restriction Trademarks National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com legal for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies Patents For patents covering National Instruments products refer to the appropriate location Help Patents in your software the patents txt file on your CD or ni com patents WARNING REGARDING USE OF NATIONAL
17. 00 yA ACOULACY emo es 0 05 Temperature drift eee ee 5 ppm C Output voltage compliance 10 V Maximum resistive load 100 KQ Overvoltage protection 40 VDC Measurement Category sse CATI Power Requirements From SCXI Backplane Mea 18 5 to 25 VDC 170 mA Maat ada 18 5 to 25 VDC 170 mA AED p NN 4 75 to 5 25 VDC 50 mA Environmental Operating temperature sess 0 to 50 C Storage temperature essesss 20 to 70 C Humidity sssr nno tos 10 to 90 RH noncondensing Maximum altitude esee 2 000 meters Pollution Degree indoor use only 2 SCXI 1503 User Manual A 4 ni com Appendix A Specifications Physical 3 0 cm 1 2 in o WI A E e B o pos 17 2 cm o 6 8 in o y Lo Dj Y gui vr gt 7 4 in i Figure A 1 SCXI 1503 Dimensions Weight teet re Eas 745 g 26 3 oz Maximum Working Voltage Maximum working voltage refers to the signal voltage plus the common mode voltage Signal common mode Each input should remain within 10 V of AI GND National Instruments Corporation A 5 SCXI 1503 User Manual Appendix A Specifications Safety This product is designed to meet th
18. 1 32 NC 37 38 39 40 DIG GND 33 34 NC a 92 NC 35 36 SCAN CLK 43 44 45 46 SER CLK 37 38 NC 47 48 NC 39 40 NC 49 50 NC 41 42 NC RSVD 43 44 NC NC 45 46 RSVD NC means no connection NC 47 48 NC RSVD means reserved NC 49 50 NC SCXI 1503 User Manual 2 10 ni com Rear Signal Connector Descriptions The rear signal connector on the cabled module is the interface between the DAQ device and all modules in the SCXI chassis AI 0 is used to differentially multiplex all 16 channels the CJ sensor and analog signals from the modules to the connected DAQ device Chapter 2 Connecting Signals The communication signals between the DAQ device and the SCXI system are listed in Table 2 4 If the DAQ device is connected to the SCXI 1503 these digital lines are unavailable for general purpose digital I O Table 2 4 SCXI 1503 50 Pin Rear Connector Signals Pin SCXI Signal Name NI DAQmx Device Signal Name Direction Description 1 2 AI GND AI GND Analog input ground connects to the analog input ground of the DAQ device AIO AIO Input Channel 0 positive used to differentially multiplex all 16 channels the CJ sensor and analog signals from the modules to the connected DAQ device AIO AIO Input Channel 0 negative used to differentially multiplex all 16 channels the CJ sensor and analog signals from the modules to the connected DAQ device 24
19. 100 uA current excitation The SCXI 1503 modules also have a digital section for automatic control of channel scanning temperature sensor selection gain selection and auto zero mode Rear Signal Connector SCXIbus Connector and SCXIbus Interface The SCXIbus controls the SCXI 1503 module The SCXIbus interface connects the rear signal connector to the SCXIbus allowing a DAQ device to control the SCXI 1503 module and the rest of the chassis Digital Control Circuitry The digital control circuitry consists of the Address Handler and registers that are necessary for identifying the module reading setting calibration information setting the gain and selecting the appropriate channel Analog Circuitry The analog circuitry per channel consists of a fixed lowpass filter and an amplifier with a software selectable gain of 1 or 100 The CJ SENSOR channel has a lowpass filter buffered by a unity gain amplifier The channels and CJ SENSOR are multiplexed to a single output buffer Analog Input Channels Each of the 16 differential analog input channels feeds to a separate instrumentation amplifier with a programmable gain of 1 or 100 Each channel has a fixed 100 uA current excitation Then the signal passes through a fixed 2 pole 5 Hz lowpass filter National Instruments Corporation 4 3 SCXI 1503 User Manual Chapter 4 Theory of Operation The CJ SENSOR input channel is used to read the sensor temperature from the termin
20. 5 11 National Instruments Corporation C cables custom 2 1 calibration SCXI 1503 5 13 CE compliance specifications A 6 channel properties configuring 5 4 channels voltage measurement flowchart figure 5 2 circuitry analog 4 3 digital control 4 3 CJC source value 3 2 common questions C 1 common software configurable settings CJC source value 3 2 gain input range 3 1 configuration 3 1 channel properties 5 4 SCXI 1503 common software settings 3 1 settings in MAX NI DAQmx 3 3 creating a global channel or task 3 3 verifying signal 3 4 NI DAQmx 3 4 configuration and testing 3 1 configuration settings gain input range 3 1 configuring channel properties 5 4 connecting resistive devices to SCXI 1503 2 2 2 wire configuration 2 4 3 wire resistive sensor connected in 2 wire configuration 2 5 4 wire configuration 2 3 lead resistance compensation using 3 wire resistive sensor and two matched current sources 2 6 SCXI 1503 User Manual Index conventions used in the manual iv creating a task DAQ Assistant 5 3 programmatically 5 3 current output channels questions about C 1 C 3 current sources operating 4 4 custom cables 2 1 D DAQ Assistant creating a task 5 3 DAQ device accessing unused analog input channels C 2 DAQ devices unavailable digital lines C 2 digital control circuitry 4 3 dynamic characteristics specifications A 3 E E M Series DAQ devices 4 4 electromagn
21. B8 Bl IEX 8 15 ground reference This is the return path for the corresponding IEX channel C24 C17 IEX lt 0 7 gt Positive Excitation Connects to the positive C8 Cl TEX lt 8 15 gt current output of the channel A3 A4 CJ SENSOR Cold Junction Temperature Sensor Input Connects to the temperature sensor of the terminal block B30 B 25 AI lt 0 7 gt Negative Input Channels Negative side of B16 B9 AI lt 8 15 gt differential input channels C32 C25 AI 0 7 Positive Input Channels Positive side of C16 C9 AI lt 8 15 gt differential input channels National Instruments Corporation 2 9 SCXI 1503 User Manual Chapter 2 Connecting Signals Rear Signal Connector Table 2 3 Rear Signal Pin Assignments Table 2 3 shows the SCXI 1503 module rear signal connector pin assignments Rear Connector Diagram Signal Name Pin Number Pin Number Signal Name AI GND 1 2 AI GND AIO 3 4 AIO NC 5 6 NC ae NC 7 8 NC 3 4 516 NC 9 10 NC m NC 11 12 NC 9 10 11112 NC 13 14 NC 13 14 NC 15 16 NC 15 16 17118 NC 17 18 NC 19 20 NC 19 20 NC 21 22 NC 21 22 NC 23 24 25 26 NC 23 24 DIG GND 27 26 SER DAT IN 25 26 SER DAT OUT 29 30 31 32 DAQ D A 27 28 NC 33 34 SLOT 0 SEL 29 30 NC 22136 NC 3
22. CK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION Conventions 3 A A N bold italic monospace The following conventions are used in this manual Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name for example P0 lt 3 0 gt The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a note which alerts 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 the product refer to the Read Me First Safety and Radio Frequency Interference document
23. INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE UNANTICIPATED USES OR MISUSES OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED SYSTEM FAILURES ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY 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 BA
24. RA fw Y ae Figure 2 4 3 Wire Configuration Using Matched Current Sources SCXI 1503 User Manual 2 6 ni com Chapter 2 Connecting Signals In this configuration the lead resistance voltage drop across R73 is converted into a common mode voltage that is rejected by the differential amplifier Also the polarity of the lead resistance voltage drops across Rr and R are series opposing relative to the inputs of the differential amplifier eliminating their effect on the voltage measured across Rzy 3 Note Rz and Rz are assumed to be equal The effectiveness of this method depends on the matching of the current sources Each current source on the SCXI 1503 has an accuracy of 0 05 This accuracy results in a worst case matching of 0 1 Refer to the Chapter 4 Theory of Operation for accuracy considerations of RTDs and thermistors Front Connector The pin assignments for the SCXI 1503 front signal connector are shown in Table 2 1 yi Note Do not make any connections to RSVD pins National Instruments Corporation 2 7 SCXI 1503 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 GND AI0 AI0 Column 31 GND AIl AIL A B C m 30 GND AR AI2 32 Oo Oo o 29 GND ALB Al3 31 o o
25. SCXI SCXI 1503 User Manual March 2007 7 NATIONAL 374271401 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 385 0 9 725 72511 France 33 0 1 48 14 24 24 Germany 49 89 7413130 India 91 80 41190000 Israel 972 3 6393737 Italy 39 02 413091 Japan 81 3 5472 2970 Korea 82 02 3451 3400 Lebanon 961 0 1 33 28 28 Malaysia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210 311 210 Russia 7 495 783 6851 Singapore 1800 226 5886 Slovenia 386 3 425 42 00 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 2005151 Taiwan 886 02 2377 2222 Thailand 662 278 6777 Turkey 90 212 279 3031 United Kingdom 44 0 1635 523545 For further support information refer to the 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 2007 National Instruments Corporation All rights reserved Import
26. al Chapter 1 About the SCXI 1503 Oneofthe following SCXI 1600 e E M Series DAQ device Computer Cabling cable adapter and sensors as required for your application C Software NI DAQ 8 1 or later Application software such as LabVIEW LabWindows CVI Measurement Studio or other programming environments C Documentation Read Me First Safety and Radio Frequency Interference DAQ Getting Started Guide SCXI Quick Start Guide SCXI 1503 User Manual Terminal block installation guide A Documentation for your software Q Tools Wire cutter Wire stripper Flathead screwdriver Phillips screwdriver National Instruments Documentation The SCXI 1503 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 e 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 SCXI 1503 User Manual 1 2 ni com Chapter 1 About the SCXI 1503 SCXI or PXI SCXI chassis manual Read this manual for maintenance information on the chassis and for installation instructions e The DAQ Getting Started Guide This document has information on i
27. al block The temperature sensor is for cold junction compensation of thermocouple measurements The CJ SENSOR channel also passes through a 5 Hz lowpass filter to reject unwanted noise on the SCXI 1503 Along with the other 16 input channels the CJ SENSOR is multiplexed to the output buffer where it can be read by the DAQ device Operation of the Current Sources The current sources on the SCXI 1503 continuously provide 16 channels of 100 A current excitation These current sources are on whenever the SCXI chassis is powered on The current sources on the SCXI 1503 are designed to be accurate to within 0 05 of the specified value with a temperature drift of no more than 5 ppm C The high accuracy and stability of these current sources makes them especially well suited to measuring resistance to a high degree of accuracy Theory of Multiplexed Operation SCXI 1503 User Manual In multiplexed mode all input channels of an SCXI module are multiplexed into a single analog input channel of the DAQ device Multiplexed mode operation is ideal for high channel count systems Multiplexed mode is typically used for performing scanning operations with the SCXI 1503 The power of SCXI multiplexed mode scanning is its ability to route many input channels to a single channel of the DAQ device The multiplexing operation of the analog input signals is performed entirely by multiplexers in the SCXI modules not inside the DAQ device or SCXI chas
28. already ground referenced doing so results in a ground loop which can adversely affect the measurement accuracy Directly grounding floating signals to the chassis ground without using a bias resistor is not recommended as this can result in noisy readings Connecting Resistive Devices to the SCXI 1503 SCXI 1503 User Manual You can connect resistive devices to the SCXI signal conditioning system in a 4 2 or 3 wire configuration Figures 2 1 through 2 4 illustrate various ways to connect sensors for current excitation and voltage measurements using the SCXI 1503 with the SCXI 1306 terminal block Refer to the appropriate ADE and SCXI documentation for information concerning setting appropriate voltage gains for the analog inputs You can use the SCXI 1306 terminal block to make signal connections to the SCXI 1503 When using the SCXI 1306 terminal block refer to the SCXI 1306 Terminal Block Installation Guide 2 2 ni com Chapter 2 Connecting Signals 4 Wire Configuration The 4 wire configuration also referred to as a Kelvin connection is shown in Figure 2 1 The 4 wire configuration uses one pair of wires to deliver the excitation current to the resistive sensor and uses a separate pair of wires to sense the voltage across the resistive sensor Because of the high input impedance of the differential amplifier negligible current flows through the sense wires This results in a very small lead resistance voltage drop error Th
29. ant Information Warranty The SCXI 1503 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 reserv
30. asurement properties table 5 7 voltage measurement properties table 5 4 0 operation of current sources 4 4 P physical specifications A 5 pin assignments front connector table 2 8 power requirements from SCXI backplane A 4 Q questions and answers C 1 R rear signal connector 4 3 descriptions 2 11 removing the SCXI 1503 from Measurement amp Automation Explorer B 1 resistive devices connecting to SCXI 1503 2 wire configuration 2 4 3 wire resistive sensor connected to 2 wire configuration 2 5 4 wire configuration 2 3 National Instruments Corporation F3 Index lead resistance compensation using 3 wire resistive sensor and two matched current sources 2 6 RTD measurement properties table 5 5 RTDs resistive temperature detectors measurement errors 4 6 overview 4 5 relationship between resistance and temperature 4 6 resistance temperature curve figure 4 7 S safety specifications A 6 SCXI 1503 calibration 5 13 common questions C 1 common software settings 3 1 communication signals table 2 11 configuration settings 3 1 major components 4 3 measurements 3 3 multiplexing 4 4 removing figure B 2 removing from SCXI chassis B 1 taking measurements See measurements using LabWindows CVI to create code 5 11 Measurement Studio to create code 5 12 SCXIbus connector 4 3 interface 4 3 self test verification troubleshooting C 1 signal connections anal
31. concnononnnonccononononnonancnnornnonnons 1 4 Verifying the SCXI 1503 Installation esee eene 1 5 Chapter 2 Connecting Signals Analog Input Signal Connections ssssssssrssrsrssrsresrsrrsresrersesrsrrsrrrrrrrsrer enn rrrrr ennen rr rer r nen n rn en 2 1 Ground Referencing the Signals essere 2 2 Connecting Resistive Devices to the SCXI 1503 sese 2 2 4 Wire Configuration ipe ee edito sia 2 3 2 Wire Configuration i rete tet reader et ED epe dep eae RE c 2 4 3 Wire Resistive Sensor Configuration eese 2 5 Lead Resistance Compensation Using a 3 Wire Resistive Sensor and Two Matched Current Sources s ssserersersrrsrsrrsresrsresrrsrsrersrnrrrsrrrerrrnrnr rn rna 2 6 Front Connector iii dto b o eei ad a e te e epe e e oot 2 7 Rear Signal Connector oue epos aee eid nite pni a ees 2 10 Rear Signal Connector Descriptions sese 2 11 Chapter 3 Configuring and Testing SCXI 1503 Software Configurable Settings essere 3 1 Common Software Configurable Settings esee 3 1 CASA ep e ein 3 1 Input Coupling nette eH Ret eere A 3 2 CIC Source Valle cuco ip re teet eden 3 2 AUtO ZetO eio ere oe ede nested 3 2 Configurable Settings in MAX cicek iiia eene eene conan cono rennen 3 2 NIE DAQfmX nee disse se fdr teo ad 3 3 Creating a Global Channel or Task eee 3 3 Verifying the Signal tne tee
32. e SCXI 1503 This chapter makes suggestions for developing your application and provides basic information regarding calibration Developing Your Application in NI DAQmx iyi Note If you are not using an NI ADE using an NI ADE prior to version 8 1 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 8 1 or later of an NI ADE This section describes how to configure and use NI DAQmx to control the SCXI 1503 in LabVIEW LabWindows CVI and Measurement Studio These ADEs provide greater flexibility and access to more settings than MAX but you can use ADEs in conjunction with MAX to quickly create a customized application Typical Program Flowchart Figure 5 1 shows a typical program voltage measurement flowchart for creating a task to configure channels take a measurement analyze the data present the data stop the measurement and clear the task National Instruments Corporation 5 1 SCXI 1503 User Manual Chapter 5 Using the SCXI 1503 Yes Create Task Using DAQ Assistant Y No Y Create a Task Create Task in DAQ Assistant or MAX Create Another Channel Programmatically Create Channel Hardware Further Configure No Channels Timing Triggering
33. e data on the MOSI and MISO lines 43 46 RSVD RSVD Input Reserved Note All other pins are not connected SCXI 1503 User Manual ni com Configuring and Testing This chapter discusses configuring the SCXI 1503 in MAX using NI DAQmx creating and testing a virtual channel global channel and or task 3 Notes You must have NI DAQmx 8 1 or later installed Refer to the SCXI Quick Start Guide if you have not already configured the chassis SCXI 1503 Software Configurable Settings This section describes how to set the gain input signal range and how to configure your software for compatible sensor types It also describes how to perform configuration of these settings for the SCXI 1503 in NI DAQmx For more information on the relationship between the settings and the measurements and how to configure settings in your application refer to Chapter 4 Theory of Operation Common Software Configurable Settings This section describes the most frequently used software configurable settings for the SCXI 1503 Refer to Chapter 5 Using the SCXI 1503 for a complete list of software configurable settings Gain Input Range Gain input range is a software configurable setting that allows you to choose the appropriate amplification to fully utilize the range of the E M Series DAQ device In most applications NI DAQ chooses and sets the gain for you determined by the input range This feature
34. e main disadvantage of the 4 wire connection is the greater number of field wires required External Sensor SCXI 1306 SCXI1503 Ri Channel X Rie Sex 5 n E One m Tisi ji n i Md m em za KNIEX A 1 i i i i Ris i i CH X 7v ON Figure 2 1 4 Wire Resistive Sensor Connected in a 4 Wire Configuration O National Instruments Corporation 2 3 SCXI 1503 User Manual Chapter 2 Connecting Signals 2 Wire Configuration SCXI 1503 User Manual The basic 2 wire configuration is shown in Figure 2 2 In this configuration an error voltage Vg is introduced into the measurement equal to the excitation current Igy times the sum of the two lead resistances Rz and Rj If we assume equal lead resistances Rz Rz Rr the magnitude of the error voltage is Vg 2R lgy This is the most commonly used configuration for connecting thermistors to a signal conditioning system because the large sensitivity of thermistors usually results in the introduction of a negligible error by the lead resistances RTDs typically have a much smaller sensitivity and nominal resistance than thermistors therefore a 2 wire configuration usually results in the introduction of larger errors by the lead resistance SCXI 1306 SCXI 1503 Channel X IEX oe Figure 2 2 2 Wire Resistive Sensor Connec
35. e new sample from every analog input channel in the group scan clock signal used to increment to the next channel after each E M Series DAQ device analog to digital conversion Signal Conditioning eXtensions for Instrumentation located in the rear of an SCXI chassis the SCXIbus is the backplane that connects modules in the same chassis to each other SCXI 1503 User Manual Glossary Sensor SER CLK SER DAT IN SER DAT OUT signal conditioning Slot 0 SLOT 0 SEL SPI CLK T thermistor Traditional NI DAQ Legacy transducer U UL VAC VDC SCXI 1503 User Manual a type of transducer that converts a physical phenomenon into an electrical signal 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 output signal the manipulation of signals to prepare them for digitizing refers to the power supply and control circuitry in the SCXI chassis slot 0 select signal serial peripheral interface clock signal a thermally sensitive resistor An upgrade to the earlier version of NI DAQ Traditional NI DAQ Legacy has the same VIs and functions and works the same way as NI DAQ 6 9 x You can use both Traditional NI DAQ Legacy and NI DAQmx on the same computer which is not possible with NI DAQ 6 9 x a device capable of converting energy from one form to another Underwriters Laboratory volts volts alternating cur
36. e requirements of the following standards of safety for electrical equipment for measurement control and laboratory use e TEC 61010 1 EN 61010 1 e UL 61010 1 CSA 61010 1 yi Note For UL and other safety certifications refer to the product label or visit ni com certification search by model number or product line and click the appropriate link in the Certification column Electromagnetic Compatibility This product is designed to meet the requirements of the following standards of EMC for electrical equipment for measurement control and laboratory use EN 61326 EMC requirements Minimum Immunity e EN 55011 Emissions Group 1 Class A CE C Tick ICES and FCC Part 15 Emissions Class A 3 Note For EMC compliance operate this device according to product documentation CE Compliance This product meets the essential requirements of applicable European Directives as amended for CE marking as follows e 73 23 EEC Low Voltage Directive safety e 89 336 EEC Electromagnetic Compatibility Directive EMC iyi Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain the DoC for this product visit ni com certification search by model number or product line and click the appropriate link in the Certification column Waste Electrical and Electronic Equipment WEEE Xx EU Customers At the end of their life cycle all products must be sent to a WEEE rec
37. emperature AI Thermcpl CJCSrc Indicates the source of Yes Thermocouple CJC Source cold junction compensation Analog Input Temperature Al Thermcpl CJC Val Specifies the Yes Thermocouple CJC Value temperature of the cold junction if the CJC source is constant value Analog Input Temperature Al Thermcpl CJCChan Indicates the channel Yes Thermocouple CJC Channel that acquires the temperature of the cold junction if CJC is 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 It is a representative sample of important properties to configure for voltage measurements For a complete list of NI DAQmx properties and more information about NI DAQmx properties refer to your ADE help file Acquiring Analyzing and Presenting After configuring the task and channels you can start the acquisition read measurements analyze the data returned and display it according to the needs of your application Typical methods of analysis include digital filtering averaging data performing harmonic analysis applying a custom scale or adjusting measurements mathematically NI provides powerful analysis toolsets for each NI ADE to help 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
38. es 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 modification of
39. etic compatibility specifications A 6 environment specifications A 4 excitation specifications A 4 F filters specifications A 3 front connector pin assignments table 2 8 G gain input range configuration 3 1 input characteristics specifications A 1 installation into SCXI chassis 1 4 SCXI 1503 User Manual 1 2 L LabVIEW developing an application 5 8 programming a task table 5 8 using a NI DAQmx channel property node 5 10 LabWindows CVI creating code for using SCXI 1503 5 11 maximum working voltage specifications A 5 Measurement amp Automation Explorer configurable settings 3 2 removing the SCXI 1503 B 1 measurement properties NI DAQmx RTD table 5 5 thermistor table 5 6 thermocouple table 5 7 voltage table 5 4 Measurement Studio creating code for using SCXI 1503 5 12 multiplexed mode operation theory 4 4 multiplexing analog input signals 4 4 SCXI 1503 4 4 with AI 0 signal 2 11 N NI DAQ version required C 1 NI DAQmx configurable settings 3 3 developing applications 5 1 acquiring analyzing and presenting 5 7 adjusting timing and triggering 5 3 completing 5 8 configuring channel properties 5 4 LabVIEW 5 8 ni com NI DAQmx channel property node 5 10 program flowchart figure 5 2 programmable properties 5 13 specifying channel strings 5 11 RTD measurement properties table 5 5 thermistor measurement properties table 5 6 thermocouple me
40. hannel Properties esee 5 4 Acquiring Analyzing and Presenting esee 5 7 Completing the Application sese 5 8 Developing an Application Using LabVIEW sse 5 8 Using a NI DAQmx Channel Property Node in LabVIEW 5 10 Specifying Channel Strings in NI DAQmx see 5 11 Text Based ADES we ters ue E ep no vide aeons 5 11 Programmable NI DAQmx Properties eee 5 13 Calibration aeree e BRUNO PS 5 13 Internal Self Calibration c derr eerta te nnne enne 5 13 External Calibration ue mL dee es ee ee Er 5 13 SCXI 1503 User Manual vi ni com Contents Appendix A Specifications Appendix B Removing the SCXI 1503 Appendix C Common Questions Glossary Index Figures Figure 2 1 4 Wire Resistive Sensor Connected in a 4 Wire Configuration 2 3 Figure 2 2 2 Wire Resistive Sensor Connected in a 2 Wire Configuration 2 4 Figure 2 3 3 Wire Resistive Sensor Configuration sse 2 5 Figure 2 4 3 Wire Configuration Using Matched Current Sources 2 6 Figure 4 1 Block Diagram of SCXI 1503 sss 4 2 Figure 4 2 2 Wire RTD Measurement essere eee 4 6 Figure 4 3 Resistance Temperature Curve for a 100 Q Platinum RTD 0020 00385 eere en ette eee I E e ue iere 4 7 Figure 4 4 Resistance Temperature Curve for a 2 252 Q Thermistor
41. is described in Chapter 5 Using the SCXI 1503 Otherwise you should determine the appropriate gain using the input signal voltage range and the full scale limits of the SCXI 1503 output You can select a gain of 1 or 100 on a per channel basis National Instruments Corporation 3 1 SCXI 1503 User Manual Chapter 3 Configuring and Testing Input Coupling The front end of the SCXI 1503 includes a software configurable switch that allows you to programmatically connect the input channels of the SCXI 1503 to either the front connector or internal ground When using autozero the coupling mode is set automatically Refer to Table 5 1 NI DAQmx Voltage Measurement Properties for details about the available input coupling modes supported by the SCXI 1503 CJC Source Value When using a terminal block that has a CJ sensor for thermocouple measurements you can set the CJC source as internal which scans the sensor at the beginning of each measurement and scales the readings accordingly Auto Zero Setting the Auto zero mode to Once improves the accuracy of the measurement With auto zero enabled the inputs of the SCXI 1503 are internally grounded The driver makes a measurement when the task begins and then subtracts the measured offset from all future measurements Configurable Settings in MAX 3 SCXI 1503 User Manual Note If you are not using an NI ADE or are using an unlicensed copy of an NI ADE additional dialog boxes f
42. is ground referenced Therefore you cannot place multiple current outputs in series Are the SCXI 1503 channels isolated with respect to each other the E M Series DAQ device or ground No The SCXI 1503 does not contain any isolation circuitry If you require isolation consider the SCXI 1124 or SCXI 1125 module instead Can I modify the SCXI 1503 circuitry to generate current at a level different than 100 A No Do not attempt to modify any circuitry in the SCXI 1503 Are there any user serviceable parts inside the SCXI 1503 No There are no fuses potentiometers switches socketed resistors or jumpers inside the module Disassembly of the module for any reason can void its warranty and nullify its accuracy specification Can I access the unused analog input channels of the E M Series DAQ device if it is directly cabled to the SCXI 1503 in a single chassis system Yes E M Series DAQ device channels 1 through 7 are available to measure unconditioned signals Use an SCXI 1180 or the 50 pin breakout connector on the SCXI 1346 or SCXI 1349 cable adapter to route signals to these channels Which digital lines are unavailable on the E M Series DAQ device if I am cabled to an SCXI 1503 module Table 2 4 shows the digital lines that are used by the SCXI 1503 for communication and scanning These lines are unavailable for general purpose digital I O if the SCXI 1503 is connected to the E M Series DAQ device C 2 ni com Appendi
43. ith respect to temperature The temperature coefficient called alpha 0 differs between RTD curves Although various manufacturers specify alpha differently alpha is most commonly 4 6 ni com Chapter 4 Theory of Operation defined as the change in RTD resistance from 0 to 100 C divided by the resistance at 0 C divided by 100 C R 100 Mz Ro KAWOCO Fx 100 C 0 where Rjo9 is the resistance of the RTD at 100 C Ro is the resistance of the RTD at 0 C For example a 100 Q platinum RTD with o 0 003911 has a resistance of 139 11 Q at 100 C Figure 4 3 displays a typical resistance temperature curve for a 100 Q platinum RTD 480 400 320 Resistance Q 240 160 80 0 80 160 240 320 400 480 560 640 720 800 880 960 Temperature C Figure 4 3 Resistance Temperature Curve for a 100 Q Platinum RTD 0 00385 National Instruments Corporation 4 7 SCXI 1503 User Manual Chapter 4 SCXI 1503 User Manual Theory of Operation Although the resistance temperature curve is relatively linear accurately converting measured resistance to temperature requires curve fitting The following Callendar Van Dusen equation is commonly used to approximate the RTD curve Ry Roll AT4 BT C T 100 where Rr is the resistance of the RTD at temperature T Ro is the resistance of the RTD at 0 C A B and C are the Callendar
44. k If you are using an ADE other than an NI ADE or if you want to explicitly create and configure a task for a certain type of acquisition you can programmatically create the task from your ADE using functions or VIs If you create a task using the DAQ Assistant you can still further configure the individual properties of the task programmatically with functions or property nodes in your ADE NI recommends creating a task programmatically if you need explicit control of programmatically adjustable properties of the DAQ system Programmatically adjusting properties for a task created in the DAQ Assistant overrides the original or default settings only for that session The changes are not saved to the task configuration The next time you load the task the task uses the settings originally configured in the DAQ Assistant Adjusting Timing and Triggering There are several timing properties that you can configure through the DAQ Assistant or programmatically using function calls or property nodes If you create a task in the DAQ Assistant you can still modify the timing properties of the task programmatically in your application When programmatically adjusting timing settings you can set the task to acquire continuously acquire a buffer of samples or acquire one point at a National Instruments Corporation 5 8 SCXI 1503 User Manual Chapter 5 E Using the SCXI 1503 time For continuous acquisition you must use a while lo
45. le 1 1 Supported SCXI 1503 Terminal Blocks Terminal Block CJC Sensor Measurement Type SCXI 1306 Yes Resistive temperature measurements TBX 96 No Custom signals SCXI 1310 No Configuring the SCXI System Software Refer to the SCXI Quick Start Guide and the user manuals of the modules in your application to configure and verify them in software SCXI 1503 User Manual 1 4 ni com Chapter 1 About the SCXI 1503 Verifying the SCXI 1503 Installation Refer to the SCXI Quick Start Guide for details about testing the SCXI chassis and module installation in software Refer to Chapter 3 Configuring and Testing for details about setting up a task and verifying the input signal National Instruments Corporation 1 5 SCXI 1503 User Manual Connecting Signals This chapter describes the input and output signal connections to the SCXI 1503 module with the module front connector and rear signal connector This chapter also includes connection instructions for the signals on the SCXI 1503 module when using the SCXI 1306 terminal block In addition to this section refer to the installation guide of the terminal block for detailed information regarding connecting the signals If you are using a custom cable or connector block refer to the Front Connector section Analog Input Signal Connections Each differential input AI and AL goes to a separate filter and amplifier that is multiplexed to the mod
46. manual describes the electrical and mechanical aspects of the SCXI 1503 module and contains information concerning its installation and operation The SCXI 1503 module provides 16 differential input channels and 16 channels of 100 uA current excitation and one cold junction sensor channel The SCXI 1503 is ideally suited for measuring resistive transducers such as RTDs or thermistors Each channel has an amplifier with a selectable gain of 1 or 100 and a lowpass filter with a 5 Hz cutoff frequency to reject 50 60 Hz noise The SCXI 1503 can programmatically connect each input to ground which greatly improves its accuracy by enabling a self calibration of each input to reduce offset drift errors You can multiplex several SCXI 1503 modules and other SCXI modules into a single channel on the DAQ device greatly increasing the number of analog input signals that you can digitize Detailed specifications of the SCXI 1503 modules are listed in Appendix A Specifications What You Need to Get Started To set up and use the SCXI 1503 you need the following items C Hardware SCXI 1503 module Oneofthe following terminal blocks SCXI 1306 front mount terminal block with screw terminal connectivity SCXI 1310 custom kit for custom connectivity TBX 96 DIN EN mount terminal block with screw terminal connectivity SCXI or PXI SCXI combo chassis National Instruments Corporation 1 1 SCXI 1503 User Manu
47. module and take measurements refer to Chapter 5 Using the SCXI 1503 National Instruments Corporation 3 5 SCXI 1503 User Manual Theory of Operation This chapter provides a brief overview and a detailed discussion of the circuit features of the SCXI 1503 module Refer to Figure 4 1 while reading this section National Instruments Corporation 4 1 SCXI 1503 User Manual Theory of Operation Chapter 4 SCXIbus Connector Rear Signal Connector eoeyelul snqixOS WOudaa uoneiqie a al nja s ej Inb t PER 1 10 u09 pue eoeyetul eubiq 1 1 n 102195 ueg yajas 1ndu 19114 ssedmo7 pue uonoeioJg Induj 338 LNO e QNO IV 0IV 0Iv 32 to 1 Mux 1 l 4 ssedmo7 Joy l4 ssedmo7 HOSN3SfO eoinos uoneqieo Front Signal Connector Figure 4 1 Block Diagram of SCXI 1503 ni com 4 2 SCXI 1503 User Manual Chapter 4 Theory of Operation The major components of the SCXI 1503 modules are as follows e Rear signal connector e SCXIbus connector e SCXIbus interface e Digital control circuitry e Analog circuitry The SCXI 1503 modules consist of 16 multiplexed input channels each with a software programmable gain of 1 or 100 Each input channel has its own lowpass filter Each channel has a fixed
48. mputed automatically from this value Analog Input Minimum ALMin Specifies the minimum value Yes Value you expect to measure The SCXI 1503 gain and E M Series DAQ device range are computed automatically from this value SCXI 1503 User Manual 5 4 ni com Chapter 5 Table 5 1 NI DAQmx Voltage Measurement Properties Continued Using the SCXI 1503 DAQ Assistant Property Short Name Description Accessible Analog Input General AI Gain Specifies a gain factor to apply No Properties Advanced to the signal conditioning Gain and Offset Gain portion of the channel The Value SCXI 1503 supports 1 or 100 Analog Input General AI AutoZeroMode Specifies when to measure Yes Properties Advanced ground NI DAQmx subtracts High Accuracy Settings the measured ground voltage Auto Zero Mode from every sample The SCXI 1503 supports None or Once Analog Input General AI Coupling Specifies the input coupling of No Properties Advanced the channel The SCXI 1503 Input Configuration supports DC and GND Coupling coupling Table 5 2 NI DAQmx RTD Measurement Properties DAQ Assistant Property Short Name Description Accessible Analog Input Temperature ALRTD Type Specifies the type of Yes RTD Type RTD connected to the channel Analog Input Temperature ALRTD RO Specifies the Yes RTD RO resistance in ohms of the sensor at 0 C Na
49. n as lines are grouped to form ports the enclosure that houses powers and controls SCXI modules clock input signal voltage that appears on both inputs of a differential amplifier a source that supplies the current needed by a sensor for its proper operation digital to analog Data Address data acquisition 1 collecting and measuring electrical signals from sensors transducers and test probes or fixtures and processing the measurement data using a computer 2 collecting and measuring the same kinds of electrical signals with A D and or DIO devices plugged into a computer and possibly generating control signals with D A and or DIO devices in the same computer a data acquisition device Examples are E M Series data acquisition devices the data acquisition device data address line signal used to indicate whether the SER DAT IN pulse train transmitted to the SCXI chassis contains data or address information a plug in data acquisition device module card or pad that can contain multiple channels and conversion devices SCXI modules are distinct from devices with the exception of the SCXI 1200 which is a hybrid G 2 ni com D GND differential amplifier DIN DIO DoC drivers driver software E EMC EMI excitation EXT CLK G gain ID TEX IEX in input impedance National Instruments Corporation G 3 Glossary digital ground signal an amplifier with two input terminals neither of which a
50. nstalling NI DAQ and the E M Series DAQ device Install these before you install the SCXI module e The SCXI hardware user manuals Read these manuals for detailed information about signal connections and module configuration They also explain in greater detail how the module works and contain application hints e Accessory installation guides or manuals Read the terminal block and cable assembly installation guides They explain how to physically connect the relevant pieces of the system Consult these guides when you are making the connections e The E M Series DAQ device documentation This documentation has detailed information about the DAQ device that plugs into or is connected to the computer Use this documentation for hardware installation and configuration instructions specification information about the DAQ device and application hints e Software documentation You may have both application software and NI DAQ software documentation National Instruments NI application software includes LabVIEW LabWindows CVI and Measurement Studio After you set up the hardware system use either your application software documentation or the NI DAQ documentation to help you write your application If you have a large complex system it is worthwhile to look through the software documentation before you configure the hardware e One or more of the following help files for software information Start Programs National Inst
51. nt amp Automation on the desktop Right click Data Neighborhood and select Create New Select NI DAQmx Task or NI DAQmx Global Channel and click Next Select Analog Input Select one of the following e Voltage e Temperature and then select one of the following Iex Thermistor RTD Thermocouple Vex Thermistor If you 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 3 3 SCXI 1503 User Manual Chapter 3 Configuring and Testing selecting channels If you are creating a channel you can only select one channel Click Next 7 Name the task or channel and click Finish 8 Select the channel s you want to configure You can select a range of channels by holding down the Shift key while selecting the channels You can select multiple individual channels by holding down the Ctrl key while selecting channels Note If you want to add channels of various measurement types to the same task click the Add Channels button to select the measurement type for the additional 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 Configure the input signal range using either NI DAQmx Task or NI DAQmx Global Channel When you set the minimum and maximum
52. nt properties to configure voltage measurements For a complete list of NI DAQmx properties and more information on NI DAQmx properties refer to your ADE help file Calibration The SCXI 1503 is shipped with a calibration certificate and is calibrated at the factory to the specifications described in Appendix A Specifications Calibration constants are stored inside the calibration EEPROM and provide software correction values your application development software uses to correct the measurements for both offset and gain errors in the module Internal Self Calibration You can self calibrate the SCXI 1503 in MAX by right clicking the module and selecting Self Calibrate The NI DAQmx Self Calibrate Device function does the same A self calibration of the SCXI 1503 grounds all the input channels and stores the resulting measurement as an offset correction constant on the module You should perform a self calibration every time you install the SCXI 1503 to a new system Note You should self calibrate the connected DAQ device before self calibrating the SCXI 1503 External Calibration If you have an accurate calibrator and DMM you can externally calibrate the SCXI 1503 gain and offset constants using NI DAQmx functions You can also calibrate the 100 WA current excitation National Instruments Corporation 5 13 SCXI 1503 User Manual Chapter 5 Using the SCXI 1503 The functions that are required for externally calibrating the SCXI
53. o le ri de 28 RSVD AI4 Al4 29 o0 o o 27 RSVD AIS AI5 28 o o 0 26 RSVD AI6 AI6 a A e g 25 RSVD AIT AIT 26 Oo o o 24 NC IEXO IEX0 25 o Oo o o4 o o o 23 NC IEXI IEX1 23 o o o 22 NC IEX2 IEX2 22 0 o 0 21 NC IEX3 IEX34 SP 3g nme se 20 RSVD IEX4 IEX44 20 o o o 19 RSVD IEX5 IEX54 19 o o o iilo e 18 NC IEX6 IEX6 1710 o o 17 NC IEX7 IEX7 16 9 o o 16 GND AIS AI8 15 o 0 o 15 GND AI9 AI9 14 o o o 14 GND AI10 ATLO 13 0 o o 129 lo o o 13 GND An1 AU l tilo o o 12 NC AI12 AI12 i0 o o o 11 NC AII3 AI13 9 o o o 10 NC ATL4 AIl4 8 o o o a a ue 9 NC AI15 AIL5 6lo o o 8 NC IEX8 IEX8 5 o o o 7 NC IEX9 IEX9 4 e 9 oe 6 NC IEX10 IEX10 3 o o o 5 NC IEX11 IEX11 2 o o o ilz d wm 4 CJ SENSOR IEX12 IEX12 Co 3 CJ SENSOR IEX13 IEX134 NC no connection 2 CGND IEX14 TEX14 RSVD reserved 1 5 V IEX15 IEX15 SCXI 1503 User Manual 2 8 ni com Chapter 2 Connecting Signals Table 2 2 Signal Descriptions Pin Signal Name Description Al 5 V 5 VDC Source Used to power circuitry on the terminal block 0 1 mA of source not protected A13 A16 GND Ground Tied to the SCXI module ground A29 A32 Al A19 A20 RSVD Reserved This pin is reserved Do not connect A25 A28 any signal to this pin A2 C GND Chassis Ground Connects to the SCXI chassis B24 B17 IEX lt 0 7 gt Negative Excitation Connects to the channel
54. og input 2 1 front connector pin assignments table 2 8 SCXI 1503 User Manual Index signals verifying 3 4 NI DAQmx 3 4 software NI DAQ version required C 1 specifications analog input A 1 CE compliance A 6 electromagnetic compatibility A 6 environment A 4 excitation A 4 filters A 3 maximum working voltage A 5 physical A 5 power requirements from SCXI backplane A 4 safety A 6 stability A 3 specifying channel strings in NI DAQmx 5 11 stability specifications A 3 T taking measurements See measurements temperature measurement with resistive transducers 4 5 connecting resistive devices to SCXI 1503 2 2 2 wire configuration 2 4 3 wire resistive sensor connected in 2 wire configuration 2 5 4 wire configuration 2 3 lead resistance compensation using 3 wire resistive sensor and two matched current sources 2 6 RTDs measurement errors 4 6 overview 4 5 relationship between resistance and temperature 4 6 SCXI 1503 User Manual 1 4 resistance temperature curve figure 4 7 thermistors measurement circuits 4 11 overview 4 10 resistance temperature characteristics 4 12 resistance temperature curve figure 4 11 theory of multiplexed operation 4 4 theory of operation analog circuitry 4 3 digital circuitry 4 3 rear signal connector 4 3 SCXIbus connector 4 3 SCXIbus interface 4 3 theory of multiplexed operation 4 4 thermistor measurement properties table 5 6 thermistors mea
55. ontrols All Controls I O DA Qmx Name Controls subpalette right click it and select New Task DAQ Assistant Create a Task Programmatically optional DAQmx Create Task vi located on the Functions All Functions NI Measurements DAQmx Data Acquisition DAQmx Advanced Task Options subpalette This VI is optional if you created and configured the task using the DAQ Assistant However if you use it in LabVIEW any changes you make to the task are not saved to a task in MAX SCXI 1503 User Manual 5 8 ni com Table 5 5 Chapter 5 Programming a Task in LabVIEW Continued Flowchart Step VI or Program Step Create Virtual Channel s DAQMX Create Virtual Channel vi located on the Functions All Functions NI Measurements DAQmx Data Acquisition subpalette Use this VI to add virtual channels to the task Select the type of virtual channel based on the measurement you plan to perform Adjust Timing Settings optional DAQmx Timing vi Sample Clock by default This VI is optional if you created and configured the 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 NI DAQmx Channel Property Node refer to the Using a NI DAQmx Channel Property Node in LabVIEW section for more information This step is optional if you created and fully configu
56. op 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 1503 access an underlying set of NI DAQmx properties Table 5 1 shows some of these properties You can use Table 5 1 to determine what kind of properties you need to set to configure the module for your application For a complete list of NI DAQmx properties refer to your ADE help file Note You cannot adjust some properties while a task is running For these properties you must stop the task make the adjustment and re start the application Tables 5 1 through 5 3 assume all properties are configured before the task is started Table 5 1 NI DAQmx Voltage Measurement Properties DAQ Assistant Short Name Description Accessible Analog Input Maximum AI Max Specifies the maximum value Yes Value you expect to measure The SCXI 1503 gain and E M Series DAQ device range are co
57. range of NI DAQmx Task or NI DAQmx Global Channel the driver selects the best gain for the measurement You also can set it through your application 10 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 11 Click Device and select Auto Zero mode if desired 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 Verifying the Signal in NI DAQmx Using a Task or Global Channel You can verify the signals on the SCXI 1503 using NI DAQmx by completing the following steps 1 Expand Data Neighborhood 2 Expand NI DAQmx Tasks 3 Click the task you created in the Creating a Global Channel or Task section 4 Selectthe channel s you want to verify You can select a block of channels by holding down the Shift key or multiple channels by holding down the lt Ctrl gt key Click OK 5 Enter the appropriate information on the Settings and Device tab SCXI 1503 User Manual 3 4 ni com Chapter 3 Configuring and Testing 6 Click the Test button 7 Click the Start button 8 After you have completed verifying the channels click the Stop button You have now verified the SCXI 1503 configuration and signal connection iyi Note For more information on how to further configure the SCXI 1503 or how to use LabVIEW to configure the
58. re tied to a ground reference whose voltage difference is amplified Deutsche Industrie Norme German Industrial Standard digital input output Declaration of Conformity software that controls a specific hardware device such as an E M Series DAQ device electromagnetic compliance electromagnetic interference a voltage or current source used to energize a sensor or circuit external clock signal the factor by which a signal is amplified sometimes expressed in decibels identifier positive excitation channel negative excitation channel inch or inches the measured resistance and capacitance between the input terminals of a circuit SCXI 1503 User Manual Glossary J jumper L lead resistance MISO MOSI multiplex multiplexed mode NC NI DAQ NI DAQmx SCXI 1503 User Manual a small rectangular device used to connect two adjacent posts on a circuit board Jumpers are used on some SCXI modules and terminal blocks to either select certain parameters or enable disable circuit functionality the small resistance of a lead wire The resistance varies with the lead length and ambient temperature If the lead wire carries excitation current this varying resistance can cause measurement error meters 1 Mega the standard metric prefix for 1 million or 106 when used with units of measure such as volts and hertz 2 mega the prefix for 1 048 576 or 22 when used with B to quantify data or computer memory
59. red 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 Display Data You can use graphical tools such as charts gauges and graphs to display the data Some display tools are located on the Controls AIl Controls Numeric Numeric Indicator subpalette and Controls AlII Controls Graph subpalette Continue Sampling For continuous sampling use a While Loop If you are using hardware timing you also need to set the DAQmx Timing vi sample mode to Continuous Samples To do this right click the terminal of the DAQmx Timing vi labeled sample mode and click Create Constant Click the box that appears and select Continuous Samples National Instruments Corporation 5 9 SCXI 1503 User Manual Using the SCXI 1503 Chapter 5 Using the SCXI 1503 Table 5 5 Programming a Task in LabVIEW Continued Flowchart Step VI or Program Step Stop Measurement DAQmx Stop Task vi This VI is optional clearing the task automatically s
60. rent volts direct current G 6 ni com Glossary VI virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument 2 a LabVIEW software module VI which consists of a front panel user interface and a block diagram program virtual channels channel names that can be defined outside the application and used without having to perform scaling operations W watts National Instruments Corporation G 7 SCXI 1503 User Manual Index Numerics 2 wire configuration of resistive devices 2 4 3 wire resistive sensor connected in 2 wire configuration 2 5 lead resistance compensation with two matched current sources 2 6 4 wire configuration of resistive devices 2 3 A adjusting timing and triggering 5 3 AIO signal multiplexing 2 11 amplifier characteristics specifications A 2 analog circuitry analog input channels 4 3 CJ SENSOR 4 3 analog input channels 4 3 analog input signal connections 2 1 ground referencing of signals 2 2 analog input signals multiplexed 4 4 analog input specifications A 1 amplifier characteristics A 2 dynamic characteristics A 3 input characteristics A 1 transfer characteristics A 1 applications developing in NI DAQmx 5 1 acquiring analyzing and presenting 5 7 completing 5 8 LabVIEW 5 8 program flowchart figure 5 2 programmable properties 5 13 specifying channel strings
61. rom 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 8 1 or later of an NI ADE This section describes where you can access each software configurable setting in MAX The location of the settings varies depending on the version of NI DAQmx you use Refer to the DAQ Getting Started Guide and the SCXI Quick Start Guide for more information on installing and configuring the hardware You can use DAQ Assistant to graphically configure common measurement tasks channels or scales 3 2 ni com NI DAQmx Chapter 3 Configuring and Testing Using NI DAQmx you can configure software settings such as sensor type and gain input signal range in the following ways Task or global channel in MAX Functions in your application 3 Note All software configurable settings are not configurable both ways This section only discusses settings in MAX Refer to Chapter 5 Using the SCXI 1503 for information on using functions in your application Dependent upon the terminal block configuration use you can use the SCXI 1503 module to make the following types of measurements Voltage input Thermocouple RTD Thermistors Creating a Global Channel or Task To create a new voltage temperature or current input NI DAQmx global task or channel complete the following steps 1 Ze 3 O National Instruments Corporation Double click Measureme
62. rrent National Instruments Corporation 4 9 SCXI 1503 User Manual Chapter 4 Theory of Operation Thermistors SCXI 1503 User Manual A thermistor is a piece of semiconductor made from metal oxides pressed into a small bead disk wafer or other shape sintered at high temperatures and finally coated with epoxy or glass The resulting device exhibits an electrical resistance that varies with temperature There are two types of thermistors negative temperature coefficient NTC thermistors whose resistance decreases with increasing temperature and positive temperature coefficient PTC thermistors whose resistance increases with increasing temperature NTC thermistors are more commonly used than PTC thermistors especially for temperature measurement applications A main advantage of thermistors for temperature measurement is their extremely high sensitivity For example a 2 252 Q thermistor has a sensitivity of 100 Q C at room temperature Higher resistance thermistors can exhibit temperature coefficients of 10 kQ C or more In comparison a 100 Q platinum RTD has a sensitivity of only 0 4 Q C Also the physically small size and low thermal mass of a thermistor bead allows a very fast response to temperature changes Another advantage of the thermistor is its relatively high resistance Thermistors are available with base resistances at 25 C ranging from hundreds to millions of ohms This high resistance diminishe
63. ruments NI DAQ NI DAQmx Help Start Programs National Instruments NI DAQ Traditional NI DAQ User Manual Start Programs National Instruments NI DAQ Traditional NI DAQ Function Reference Help You can download NI documents from ni com manuals To download the latest version of NI DAQ click Drivers and Updates at ni com National Instruments Corporation 1 8 SCXI 1503 User Manual Chapter 1 About the SCXI 1503 Installing Application Software NI DAQ and the E M Series DAQ Device Refer to the DAQ Getting Started Guide packaged with the NI DAQ software to install your application software NI DAQ driver software and the DAQ device to which you will connect the SCXI 1503 NI DAQ 8 1 or later is required to configure and program the SCXI 1503 module If you do not have NI DAQ 8 1 or later you can either contact an NI sales representative to request it on a CD or download the latest NI DAQ version from ni com 3 Note Refer to the Read Me First Radio Frequency Interference document before removing equipment covers or connecting or disconnecting any signal wires Installing the SCXI 1503 Module into the SCXI Chassis Refer to the SCXI Quick Start Guide to install your SCXI 1503 module Installing the Terminal Block Table 1 1 shows the supported SCXI 1503 terminal blocks Refer to the SCXI Quick Start Guide and the terminal block installation guide for more information about the terminal block Tab
64. s 0 005 FSR Input offset error RTD Gain 1 Calibrated ssssss 650 UV max 250 UV typ With autozero enabled 300 uV max 150 uV typ Assumes 1 000 point average 25 C 10 C over one year 2 Assumes 1 000 point average 1 C of autozero temperature National Instruments Corporation A 1 SCXI 1503 User Manual Appendix A Specifications Gain 100 Calibrated arneo 25 UV max 10 uV typ With autozero enabled 10 uV max 5 UV typ Gain error relative to calibration reference Gain 1 or 100 Calibrated sss 0 07496 of reading max 0 02 of reading typ RTD Measurement Accuracy Table A 1 RTD Measurement Accuracy Measured Temperature C 100 Q Max C 100 Q Typ C 1000 Q Max C 1000 Q Typ C 100 to 0 0 60 0 23 1 09 0 46 0 to 25 0 62 0 23 1 11 0 47 25 to 100 0 69 0 25 1 20 0 49 100 to 500 1 11 0 37 1 68 0 65 500 to 1200 2 06 0 65 2 81 1 04 Notes The accuracies in this table reflect using the module in4 wire mode They do not include errors from the RTD including lead wire errors when using 2 or 3 wire connection The accuracies assume auto zero is enabled and the environmental conditions are 25 C 10 C over a one year period These accuracies were computed using a standard RTD with a TCR of 3851 Amplifier Characteristics Input coupling genooi DC Input impedance Normal powered on
65. s the effect of inherent resistances in the lead wires which can cause significant errors with low resistance devices such as RTDs For example while RTD measurements typically require 3 or 4 wire connections to reduce errors caused by lead wire resistances 2 wire connections to thermistors are usually adequate The major trade off for the high resistance and sensitivity of the thermistor is its highly nonlinear output and relatively limited operating range Depending on the type of thermistor the upper range is typically limited to around 300 C Figure 4 4 shows the resistance temperature curve for a 2 252 Q thermistor The curve of a 100 Q RTD is also shown for comparison 4 10 ni com Chapter 4 Theory of Operation Resistance Q National Instruments Corporation 10M 1M 100k 10k 1k 100 10 Thermistor 2 252 Q at 25 C RTD PT 100 Q Temperature C Figure 4 4 Resistance Temperature Curve for a 2 252 2 Thermistor The thermistor has been used primarily for high resolution measurements over limited temperature ranges However continuing improvements in thermistor stability accuracy and interchangeability have prompted increased use of thermistors in a variety of applications Thermistor Measurement Circuits This section details information about thermistor measurement circuits The most common technique is to use a current source and measure the voltage developed across
66. sis In multiplexed mode the SCXI 1503 scanned channels are kept by the NI DAQ driver in a scan list Immediately prior to a multiplexed scanning operation the SCXI chassis is programmed with a module scan list that controls which module sends its output to the SCXIbus during a scan through the cabled SCXI module The list can contain channels in any physical order and the multiplexer can sequence the channel selection from the scan list in any order The ordering of scanned channels need not be sequential Channels can occur multiple times in a single scan list The scan list can contain an arbitrary number of channels for each module entry in the scan list limited to a total of 512 channels per DAQ device This is referred to as flexible scanning random scanning Not all SCXI modules provide flexible scanning 4 4 ni com Chapter 4 Theory of Operation The module includes first in first out FIFO memory for storing the channel scan list defined in your application code NI DAQ drivers load the FIFO based on the channel assignments you make in your application You need not explicitly program the module FIFO as this is done automatically for you by the NI DAQ driver When you configure a module for multiplexed mode operation the routing of multiplexed signals to the DAQ device depends on which module in the SCXI system is cabled to the DAQ device There are several possible scenarios for routing signals from the multiplexed modules to the
67. surement circuits 4 11 overview 4 10 resistance temperature characteristics 4 12 resistance temperature curve figure 4 11 thermocouple measurement properties table 5 7 timing and triggering adjusting 5 3 transfer characteristics specifications A 1 troubleshooting incorrect test and verification C 1 V verifying signal 3 4 NI DAQmx 3 4 troubleshooting C 1 Visual Basic creating code for the SCXI 1503 5 11 ni com
68. teAIVoltageChan SC1Mod1 ai0 System String physicalChannelName Voltage0 System String nameToAssignChannel 10 0 System Double minVal 10 0 System Double maxVal setting attributes after the channel is created AIChannel myChannel myTask AIChannels Voltage0 myChannel AutoZeroMode kAutoZeroTypeOnce Modify the example code above or the code from one of the shipping examples as needed to suit your application iyi Note You can create and configure the voltage measurement task in MAX and load it into your application with the function call NationalInstruments DAQmx DaqSystem Local LoadTask Refer to the NJ Measurement Studio Help for more information on creating NI DAQmx tasks in LabWindows CVI and NI DAQmx property information SCXI 1503 User Manual 5 12 ni com Chapter 5 Using the SCXI 1503 Programmable NI DAQmx Properties All of the different ADEs that configure the SCXI 1503 access an underlying set of NI DAQmx properties Tables 5 1 through 5 4 provide a list of some of the properties that configure the SCXI 1503 You can use this list to determine what kind of properties you need to set to configure the device for your application For a complete list of NI DAQmx properties refer to your ADE help file hy Note Tables 5 1 through 5 4 are not complete lists of NI DAQmx properties and do not include every property you may need to configure voltage measurements It is a representative sample of importa
69. ted in a 2 Wire Configuration 2 4 ni com Chapter 2 Connecting Signals 3 Wire Resistive Sensor Configuration If you are using a 3 wire resistive sensor you can reduce the error voltage by one half over the 2 wire measurement by connecting the device as shown in Figure 2 3 In this configuration very little current flows through Rz and therefore R gt is the only lead resistance that introduces an error into the measurement The resulting measurement error is VE Ryley External Sensor SCXI 1308 5 SCXI1503 i R i M y Channel X i i S iEx A i i Ris EP Al ot S i Ry Sar mae RIMIS Ri SEX CHX NW i ON Figure 2 3 3 Wire Resistive Sensor Configuration National Instruments Corporation 2 5 SCXI 1503 User Manual Chapter 2 Connecting Signals Lead Resistance Compensation Using a 3 Wire Resistive Sensor and Two Matched Current Sources You can compensate for the errors introduced by lead resistance voltage drops by using a 3 wire resistive sensor and two matched current sources connected as shown in Figure 2 4 External Sensor SCXI 1306 SCXI1503 Ru Exo WWW s SN on Pr ON d BEL ODE EL Urea o NA F Sr gt e t 100 pA OB
70. the SCXI 1503 is the module cabled to the E M Series DAQ device disconnect the cable Remove any terminal block that connects to the SCXI 1503 B 1 SCXI 1503 User Manual Appendix B Removing the SCXI 1503 4 Rotate the thumbscrews that secure the SCXI 1503 to the chassis counterclockwise until they are loose but do not completely remove the thumbscrews Remove the SCXI 1503 by pulling steadily on both thumbscrews until the module slides completely out 1 Cable 3 SCXI 1503 5 SCXI Chassis Power Switch 2 SCXI Module Thumbscrews 4 Terminal Block 6 SCXI Chassis Figure B 1 Removing the SCXI 1503 SCXI 1503 User Manual B 2 ni com Common Questions This appendix lists common questions related to the use of the SCXI 1503 Which version of NI DAQ works with the SCXI 1503 and how do I get the most current version of NI DAQ You must have NI DAQ 8 1 or later Visit the NI Web site at ni com and select Download Software Drivers and Updates Search Drivers and Updates Enter the keyword NI DAQ to find the latest version of NI DAQ for your operating system I cannot correctly test and verify that my SCXI 1503 is working What should I do Unfortunately there is always the chance that one or more components in the system are not operating correctly You may have to call or email a technical support representative The technical support representative often suggests troubleshooting measures If req
71. the thermistor Figure shows the measured voltage Vo equals R7 X Igy or O Vo Zz Ry 0 Thermistor e Vo lex X RT Figure 4 5 Thermistor Measurement with Constant Current Excitation 4 11 SCXI 1503 User Manual Chapter 4 Theory of Operation SCXI 1503 User Manual The maximum resistance of the thermistor is determined from the current excitation value and the maximum voltage range of the input device When using the SCXI 1503 the maximum measurable resistance is 100 kO The level of the voltage output signal depends directly on the thermistor resistance and magnitude of the current excitation Do not use a higher level of current excitation in order to produce a higher level output signal because the current causes the thermistor to heat internally leading to temperature measurement errors This phenomena is called self heating When current passes through the thermistor power dissipated by the thermistor equaling y R7 heats the thermistor Thermistors with their small size and high resistance are particularly prone to these self heating errors Manufacturers typically specify this self heating as a dissipation constant which is the power required to heat the thermistor 1 C from ambient temperature mW C The dissipation constant depends heavily on how easily heat is transferred away from the thermistor so the dissipation constant can be specified for different media in still air water
72. tional Instruments Corporation 5 5 SCXI 1503 User Manual Chapter 5 Using the SCXI 1503 Table 5 2 NI DAQmx RTD Measurement Properties Continued DAQ Assistant Property Short Name Description Accessible Analog Input Temperature ALRTD A Specifies the A B or Yes RTD Custom A B C ALRTD B C constant of the ALRTD C Callendar Van Dusen equation when using a custom RTD type Analog Input General Al Resistance Cfg Specifies the Yes Properties Signal resistance Conditioning Resistance configuration for the Configuration channel such as 2 wire 3 wire or 4 wire Table 5 3 NI DAQmx Thermistor Measurement Properties DAQ Assistant Property Short Name Description Accessible Analog Input Temperature AL Thrmistr R1 Specifies the resistance in Yes Thermistor R1 ohms of the sensor at 0 C Analog Input Temperature Al Thrmistr A Specifies the A B or C Yes Thermistor Custom A B C AI Thrmistr B constant of the Steinhart Hart AI Thrmistr C thermistor equation which NI DAQmx uses to scale thermistors SCXI 1503 User Manual 5 6 ni com Chapter 5 Table 5 4 NI DAQmx Thermocouple Measurement Properties Using the SCXI 1503 DAQ Assistant Property Short Name Description Accessible Analog Input Temperature AI Thermcpl Type Specifies the type of Yes Thermocouple Type thermocouple connected to the channel Analog Input T
73. tops the task Clear Task DAQmx Clear Task vi Using a NI 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 DAQmx Data Acquisition and select DAQmx Channel Property Node 5 The ActiveChans property is displayed by default This allows you 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 Active Channels box and assign the appropriate channel to each list of properties 3 Note Ifyou do not use Active Channels the properties are set on all of the channels in the task SCXI 1503 User Manual 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 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 9
74. uesting technical support by phone have the system nearby so you can try these measures immediately NI contact information is listed in the Technical Support Information document Can the SCXI 1503 current outputs be interactively controlled in MAX or programmatically controlled using NI DAQ function calls LabVIEW or Measurement Studio No The current output level is 100 uA as long as the chassis is powered on You cannot power off or adjust the current output using MAX NI DAQ function calls or an ADE such as LabVIEW or Measurement Studio If you require this functionality consider using an SCXI 1124 module or NI 670X device instead How can I ground a floating voltage measurement You can use the IEX terminal of each channel as a ground reference Refer to the SCXI 1306 Terminal Block Installation Guide for details about using the SCXI 1306 DIP switches to control ground referencing National Instruments Corporation C 1 SCXI 1503 User Manual Appendix C Common Questions SCXI 1503 User Manual Can I comnect N current output channels in parallel to create a precision current source that provides N x 100 uA Yes you can connect the current output in parallel When connecting the output in parallel connect the appropriate IEX terminals together and the corresponding IEX terminals together Can I connect N current output channels in series to achieve a higher terminal voltage compliance limit No Each current source
75. ule output buffer If the terminal block has a temperature sensor the sensor output connected to pins A3 and or A4 CJ SENSOR is also filtered and multiplexed to the module output buffer The differential input signal range of an SCXI 1503 module input channel is 10 V when using a gain of 1 or x0 1 V when using a gain of 100 This differential input range is the maximum measurable voltage difference between the positive and negative channel inputs The common mode input signal range of an SCXI 1503 module input channel is 10 V This common mode input range for either positive or negative channel input is the maximum input voltage that results in a valid measurement Each channel includes input protection circuitry to withstand the accidental application of voltages up to 42 VDC powered on or x25 VDC powered off UN Caution Exceeding the input damage level 42 VDC powered on or 25 VDC powered off between input channels and chassis ground can damage the SCXI 1503 module the SCXIbus and the DAQ device NI is not liable for any injuries resulting from such signal connections National Instruments Corporation 2 1 SCXI 1503 User Manual Chapter 2 Connecting Signals B Note Exceeding the differential or common mode input channel ranges results in a distorted signal measurement and can also increase the settling time requirement of the connected E M Series DAQ device Ground Referencing the Signals Do not ground signals that are
76. x C Common Questions Does short circuiting a current output channel do any damage to the SCXI 1503 No The SCXI 1503 delivers 100 uA into any load from 0 Q to 100 KQ Does open circuiting a current output channel damage the SCXI 1503 What is the open circuit voltage level No An SCXI 1503 current output channel is not damaged if no load is connected The open circuit voltage is 12 4 VDC National Instruments Corporation C 3 SCXI 1503 User Manual Glossary Symbol Prefix Value u micro 1076 m milli 10 3 k kilo 103 M mega 106 Numbers Symbols percent positive of or plus negative of or minus plus or minus lt less than per 3 degree Q ohms 5 V signal 5 VDC source signal A A amperes ADE application development environment such as LabVIEW LabWindows CVI Visual Basic C and C AI analog input AI GND analog input ground signal National Instruments Corporation G 1 SCXI 1503 User Manual Glossary bit C CE C GND channel chassis CLK common mode voltage current excitation D D A D A DAQ DAQ device DAQ D A device SCXI 1503 User Manual one binary digit either O or 1 European emissions control standard chassis ground signal 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 also know
77. ycling center For more information about WEEE recycling centers and National Instruments WEEE initiatives visit ni com environment weee htm SCXI 1503 User Manual A 6 ni com Removing the SCXI 1503 This appendix explains how to remove the SCXI 1503 from MAX and an SCXI chassis or PXI SCXI combination chassis Removing the SCXI 1503 from MAX To remove a module from MAX complete the following steps after launching MAX 1 Expand Devices and Interfaces 2 Click the next to NI DAQmx to expand the list of installed chassis 3 Click the next to the appropriate chassis to expand the list of installed modules 4 Right click the module or chassis you want to delete and click Delete A confirmation window opens Click Yes to continue deleting the module or chassis or No to cancel this action iyi Note Deleting the SCXI chassis deletes all modules in the chassis All configuration information for these modules is also lost The SCXI chassis and or SCXI module s should now be removed from the list of installed devices in MAX Removing the SCXI 1503 from a Chassis Consult the documentation for the chassis and accessories for additional instructions and precautions To remove the SCXI 1503 module from a chassis complete the following steps while referring to Figure B 1 1 National Instruments Corporation Power off the chassis Do not remove the SCXI 1503 module from a chassis that is powered on If

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