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NI 435x User Manual - National Instruments

1. 4 wire ohms measurement modes is Off Measuring Temperature with Thermocouples A thermocouple which measures temperature operates on the principle that the junction of two dissimilar metals generates a voltage that varies with temperature or thermal electromotive force EMF However just measuring this voltage is not sufficient because connecting the thermocouple to the NI 435x accessory creates the reference junction or cold junction shown in Figure 2 2 These additional junctions act as thermocouples and produce their own voltages Thus the final measured voltage V measured includes both the thermocouple voltage V thermocouples and the cold junction voltage V coid junction The method of compensating for these unwanted cold junction voltages is called cold junction compensation CJC NI 435x User Manual 2 6 ni com Chapter 2 Operating the NI 435x Device Q Vihermocouple Vmeasured V4 Vmeasured Vihermocouple V4 Vo where Veold junction Figure 2 2 Effect of the Cold Junction With the NI 435x you can perform CJC in software in three ways as follows National Instruments Corporation Using the built in thermistor temperature sensor on an NI 435x accessory to measure the ambient temperature at the cold junction and compute the appropriate compensation for the unwanted thermoelectric voltages using software The cold junction sensor is on analog channel 0 on the TC 219
2. Chapter 2 Operating the NI 435x Device The DIO lines of the NI 435x are protected against damage from voltages within 0 5 and 5 5 V with respect to digital ground DGND Never apply voltages above these levels to these signals Note If the number of digital input lines is inadequate for the application use the analog input channels to measure the voltage of the digital signal you want to measure Determine the logic level based on the thresholds of the logic family of the digital signal Table 2 6 shows thresholds of CMOS and TTL logic families using analog inputs as digital inputs Table 2 6 Logic Family Thresholds Logic Family Low High CMOS lt 0 8 V gt 2 0 V TTL lt 0 8 V 22 0 V Note Check the logic family data sheets for any variations NI 435x User Manual 2 30 ni com Specifications This appendix lists the specifications of the NI 4350 and NI 4351 These specifications are for a 15 C to 35 C ambient temperature range within one year of calibration unless otherwise specified All specifications are relative to calibration standards and require a 30 minute warm up period Specifications do not include transducer errors Temperature coefficient is applicable for 0 C to 15 C and 35 C to 55 C For thermocouples add the accessory error in C only if the accessory TC 2190 TBX 68T or CB 68T is in the 0 C to 15 C and 35 C to 55 C temperature range Accuracy Specif
3. In single channel measurements the reading rate is the same as the notch filter frequency 10 50 or 60 readings s In multiple channel measurements the reading rates adjust to allow the analog and digital filters to settle to the specified accuracy Note determine the reading rate per channel when scanning multiple channels divide the multiple channel measurement reading rate in Table 2 1 by the number of channels in the scan In certain applications such as resistance measurements above 25 kQ or voltage measurements with more than 25 kQ of source resistance you should measure the same channel for up to 1s then switch to another channel to achieve the specified accuracy This extra time allows the input filter capacitors of the NI 435x devices to fully charge or discharge To optimize measurement accuracy and minimize the noise level choose the 10 Hz notch filter setting In practice most of the noise encountered in measurements occurs at harmonics multiples of the local powerline frequency PLF Table 2 1 shows which filter settings reject harmonics of particular frequencies National Instruments Corporation 2 3 NI 435x User Manual Chapter 2 Operating the NI 435x Device Table 2 1 Filtering and Sample Rates Equivalent NI DAQ NI 435x Filter Setting Harmonics Single Multiple of Noise Channel Channel Notch Filter Frequencies Measurement Measurement Frequency PLF Reading PLF Re
4. 1 UV C 0 5V 1010020 A 6 ni com Analog Input Input Characteristics Number of channels Calibration cycle esses Input coupling Over voltage protection CH 0 8 15 Inxs Igxoz Tex 1 ca Esa esa SURE UNTER ge EO E a VUES Data transfers eeeeeeeeeee Warm up time esee Amplifier Characteristics Input impedance Normal powered on Powered off sss Overloads ette Open thermocouple detection Ground referencing sese Input bias current eeeeeee CMR DC 50 Hz 60 Hz 400 Hz Range 22 5 V iussis Range 2 5 V aee tete tos NMR 50 Hz 60 Hz 400 H2 National Instruments Corporation A 7 Appendix A Specifications 16 differential or 14 thermocouple 5 1 2 Sigma delta 24 bits no missing codes 1 year DC 42 V powered on 17 V powered off Interrupts programmed I O 30 minutes gt 1 GQ in parallel with 0 39 uF 10 kQ 10 KQ 10 MQ between CH and 2 5 V software selectable 10 MQ between CH and ground software selectable 80 dB 100 dB gt 100 dB NI 435x User Manual Appendix Specifications Dynamic Characteristics Bandwidth erre 20 Hz Step response full scale step Accura
5. 9 National Instruments Corporation 2 19 NI 435x User Manual Chapter 2 Operating the NI 435x Device Introduction to RTDs NI 435x User Manual An 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 can be made of different metals and can 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 accuracy 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 can be difficult to measure because they have relatively low resistance 100 that changes only slightly with temperature less than 0 4 To accurately measure these small changes in resistance you may need to use special configurations that minimize errors from lead wire resistance Relationship of Resistance and Temperature in RTDs Compared to other temperature devices the output of an RTD is relatively linear with respect to temperature The temperature coefficient alpha differs between RTD curves Although various manufacturers may specify differently is most commonly defined as the change in RTD resistance from 0 C to 100 C divided by the resistance at 0
6. Verify that the NI 435x device name appears under Traditional NI DAQ Legacy Devices If the NI 435x device name does not appear press F5 to refresh the view in MAX If the device is still not recognized refer to ni com support install for troubleshooting information Right click the NI 435x device name and select Properties to open the Configuring Device window Configure the device properties including accessories in the Accessory tab Click Apply to accept the changes Click Test Resources in the System tab of the Configuring Device window When the self test finishes a message indicates successful verification or if an error occurred If an error occurs refer to ni com support install for troubleshooting information Click OK to close the Configuring Device window 1 8 ni com Chapter 1 Introduction Creating a Task in VI Logger This section explains how to configure and run a task using VI Logger with the NI 435x hardware and how to view or export the resulting data UN Caution To use VI Logger with the NI 435x devices you must activate VI Logger Refer to ni com license to activate VI Logger Before you create a VI Logger task you should confirm that you have properly configured the NI 435x hardware and associated accessories if applicable as outlined in Configuring the Hardware in MAX Using Virtual Channels with VI Logger Before you create a VI Logger task for an NI DAQ traditional virtual channe
7. ground referencing on that channel Otherwise the thermocouple inputs may float out of the input common mode limits of the NI 435x device On all the NI 435x accessories used with thermocouples analog channel CHO is dedicated to the thermistor cold junction sensor The built in current source return terminal _ or Igyo is tied to 22 5 V through a resistor This 2 5 V references any resistor excited by the current source to ground Since this current source excites the cold junction thermistor CHO is automatically ground referenced Therefore when measuring the voltage across this thermistor always switch off programmable ground referencing on CHO Otherwise the leakage current flowing into the thermistor may cause erroneous measurements in all the channels that use the current source Current source terminal Igy also is tied to 2 5 V through a resistor 3 Note When using VI Logger in MAX with Traditional NI DAQ Legacy virtual channels the ground referencing switch on the cold junction sensor channel and Auto Zero channel is automatically set appropriately National Instruments Corporation 2 9 NI 435x User Manual Chapter 2 Operating the NI 435x Device NI 435x User Manual Programmable Open Thermocouple Detection To detect open or broken thermocouples switch on open thermocouple detection on that channel Then if the thermocouple breaks the voltage on that channel rises rapidly above 100 mV at which point you can c
8. input range Thermal EMF Thermoelectric potentials or thermal EMFs are voltages generated at the junctions of dissimilar metals and are functions of temperature Thermal EMFs in the source generating the signal can introduce errors in measurements that change with variations in temperature To minimize thermal EMFs use copper wires to connect the signal to the NI 435x accessory Avoid using dissimilar metal wires in connections Also keep out temperature gradients in the space enclosing the signal source the NI 435x and its accessories Using Digital Inputs and Outputs The NI 435x features TTL compatible digital lines These lines can be individually configured either as digital inputs or as outputs When the NI 435x hardware powers on these digital lines are configured as high impedance inputs You can use the DIO lines as an interface to control processes to control events such as turning on and off heaters relays motors or lights to generate patterns for testing and to communicate with peripheral equipment If the current and voltage specifications of the DIO lines are not appropriate for the requirements you can use external signal conditioning such as electromechanical relay solid state relay opto coupler and so on You can use the digital input lines to trigger analog acquisitions To trigger analog acquisitions with LabVIEW or NI 435x set up the analog acquisition configuration poll the digital input line for t
9. operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com legal for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies Members of the National Instruments Alliance Partner Program are business entities independent from National Instruments and have no agency partnership or joint venture relationship with National Instruments 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 INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN
10. section for more information about connection precautions and for examples of how you can use different transducers connected to analog channels in the same measurement setup Note Use the 25 uA current source for thermistors above 1 KQ to avoid self heating Refer to the Self Heating section for further details Optimizing Measurements In addition to the potential problems discussed in the sections on connecting the RTDs and thermistors also consider other problems associated with AC noise effects thermal EMF and other errors as discussed in the following sections Auto Zero Auto Zero removes any offset errors in the measurement Analog channel 1 CH1 on the TC 2190 TBX 68T and CB 68T is dedicated for Auto Zero CH1 is connected to CH1 on these accessories When using a TBX 68 accessory connect CH to CH any channel to make that channel useful for Auto Zero You can measure the voltage offset on this Auto Zero channel and subtract it from the voltage measurements on other channels This way you can compensate for any residual offset error This is especially useful when the NI 435x is operating at an ambient temperature other than that of calibration 23 typical National Instruments Corporation 2 25 NI 435x User Manual Chapter 2 Operating the NI 435x Device Programmable Ground Referencing Always switch off ground referencing on the channel connected to a resistor excited by the current source The curre
11. C divided by 100 C as follows a Ro RoI 100 C where is the resistance of the RTD at 100 C and Ro is the resistance of the RTD at 0 C For example a 100 Q platinum RTD with 0 00385 measures 138 5 Q at 100 C Figure 2 9 shows a typical resistance temperature curve for a 100 platinum RTD 2 20 ni com Chapter 2 Operating the NI 435x Device RTD PT 100 Q 1000 S 8 100 S 2 7 o tc 10 4 200 100 50 0 50 100 150 200 250 300 350 400 Temperature C Figure 2 9 Resistance Temperature Curve for a 100 Q Platinum RTD Although the resistance temperature curve is relatively linear converting measured resistance to temperature accurately requires curve fitting The Callendar Van Dusen equation is commonly used to approximate the RTD curve Rerp Rofl A X t B x t C x t 100 x t3 where is the resistance of the RTD at temperature Ro is the resistance of the RTD in Q at 0 C A B and C are the Callendar Van Dusen coefficients shown in Table 2 4 and is the temperature in C For temperatures above 0 C coefficient C equals 0 Therefore for temperatures above 0 C this equation reduces to a quadratic 1 R R A n 4B Rro z 1 Ro Most platinum RTD curves follow one of three standardized curves the DIN 43760 standard 0 00385 the U S Ind
12. Interference document in the NI PXI 4351 shipping kit or at com manuals 2 NI PCI 4351 Remove the filler panel from an unused PXI slot Touch any metal part of the chassis to discharge static electricity Ensure that the injector ejector handle on the NI PXI 4351 is not latched and swings freely Place the NI PXI 4351 edges into the device guides at the top and bottom of the chassis Slide the NI PXI 4351 into the PXI slot to the rear of the chassis When you begin to feel resistance pull up on the injector ejector handle to fully insert the NI PXI 4351 Secure the NI 4351 to the chassis front panel mounting rail using the front panel mounting screws Plug in and power on the PXI chassis Complete the following steps and refer to Figure 1 2 to install the NI PCI 4351 1 NI PCI 4351 2 PCI Slot Figure 1 2 Installing the NI PCI 4351 1 Power off and unplug the computer National Instruments Corporation 1 5 NI 435x User Manual Chapter 1 Introduction Caution Before removing equipment covers or connecting or disconnecting any signal wires refer to the Read Me First Safety and Radio Frequency Interference document in the NI PCI 4351 shipping kit or at ni com manuals NI USB 4350 NI 435x User Manual 2 Remove the computer cover and or the expansion slot cover 3 Touch any metal part of the computer to discharge static electricity 4 Insert the device into
13. 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 BACK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USE
14. a PCI slot Gently rock the device into place Do not force the NI PCI 4351 into place 5 Secure the device mounting bracket to the computer back panel rail Replace the computer cover if applicable Plug in and power on the computer To install the NI USB 4350 connect the cable from the computer USB port to an available USB port on the NI USB 4350 Figure 1 3 shows the USB cable and its connectors 1 Connector to the Computer or USB Hub 2 Connector to the NI USB 4350 Figure 1 3 USB Cable and Connectors When you connect the NI USB 4350 to the PC the computer recognizes the NI USB 4350 immediately and the LED on the device front panel blinks or lights up depending upon the status of the NI USB 4350 Power Considerations The NI USB 4350 is powered on only when the USB cable connects the NI USB 4350 to the host PC and the PC is powered on The NI USB 4350 is designed to run in a stand alone mode drawing power only from the USB cable At times the NI USB 4350 may require more power than the USB power supply can safely deliver If the NI USB 4350 tries to draw more than the allowed current from the USB power supply internal protection circuitry turns off most of the circuitry in the NI USB 4350 to 1 6 ni com 3 Chapter 1 Introduction protect the USB power supply This over current condition makes the LED blink in the power supply overload pattern described in the LED Patterns section Note When th
15. column Electromagnetic Compatibility Emissions EN 55011 Class at 10 FCC Part 15 above 1 GHz Mamnun tyn EN 61326 1997 A2 2001 Table 1 EMC EMII eee CE C Tick and FCC Part 15 Class A Compliant Note For EMC compliance operate this device with shielded cabling CE Compliance The NI 435x devices meet the essential requirements of applicable European Directives as amended for CE marking as follows Low Voltage Directive safety 73 23 EEC Electromagnetic Compatibility Directive EMC sees 89 336 EEC 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 National Instruments Corporation A 11 NI 435x User Manual Signal Connections This section lists the pinouts of the NI 435x The TBX 68 accessory is an extension of the connector of the NI 435x device therefore the pinout of the screw terminal of the TBX 68 corresponds to the pinout of the NI 435x device Table B 1 shows how the screw terminals on the TBX 68 connector block and the SH6868 cable and the R6868 cables correspond to the signal names on the NI 435x USB PXI PCI Table B 1 Using the NI 435x USB PXI PCI w
16. curves or tables for their particular devices The thermistor curve however can be approximated relatively accurately with the Steinhart Hart equation 1 ee a bx e X In Rp Where T K is the temperature in kelvin equal to T C 273 15 and R is the resistance of the thermistor The coefficients a b and c can be provided by the thermistor manufacturer or calculated from the resistance versus temperature curve 2 24 ni com Chapter 2 Operating the NI 435x Device Software packages such as LabVIEW and LabWindows CVI include routines that perform these conversions for some types of thermistors You also can modify these conversion routines for the particular type of thermistor Connecting the Thermistor You can use signal connection techniques described in the Connecting Resistors section for any thermistor The high resistance and high sensitivity of the thermistor simplify the necessary measurement circuitry and signal conditioning 3 wire or 4 wire connections as shown in Figures 2 4 2 5 and 2 6 are not necessary The value of the lead resistance is negligible compared to the resistance value of the thermistor Therefore a 2 wire connection as shown in Figure 2 3 is sufficient You can use the same current excitation for several resistors as long as you do not exceed the maximum load and are within the common mode voltage specification Refer to the Input Ranges section in the Connecting Resistors
17. mA typical when using the NI USB 4350 National Instruments Corporation B 3 NI 435x User Manual Technical Support and Professional Services Visit the following sections of the National Instruments Web site at ni com for technical support and professional services National Instruments Corporation Support Online technical support resources at ni com support include the following Self Help Resources For answers and solutions visit the award winning National Instruments Web site for software drivers and updates a searchable KnowledgeBase product manuals step by step troubleshooting wizards thousands of example programs tutorials application notes instrument drivers and so on Free Technical Support All registered users receive free Basic Service which includes access to hundreds of Application Engineers worldwide in the NI Developer Exchange at ni com exchange National Instruments Application Engineers make sure every question receives an answer For information about other technical support options in your area visit ni com services or contact your local office at ni com contact Training and Certification Visit ni com training for self paced training eLearning virtual classrooms interactive CDs and Certification program information You also can register for instructor led hands on courses at locations around the world System Integration If you have time constraints limited in hous
18. parameters in the Virtual Channel Test Panels dialog box Click Close when you are finished Creating and Configuring a Task When you configure a logging task VI Logger provides feedback if any choices you make are invalid Complete the following steps to create a data logging task 1 Launch VI Logger by selecting Start Programs National Instruments VI Logger VI Logger in MAX 2 In the configuration tree in MAX right click VI Logger Tasks and select Create New The Create New dialog box appears 3 Select Using Traditional NI DAQ Legacy and click Finish In the MAX configuration tree the newly created task is selected and the Task Attributes view is selected Note If you only use NI DAQmx rather than Traditional NI DAQ Legacy you must still activate the VI Logger license Refer to ni com license for more information NI 435x User Manual VI Logger automatically gives the task a unique default name which appears under VI Logger Tasks You can rename the task by right clicking on the task name and selecting Rename Task In the Acquisition Settings section enter the following fields a Inthe Device field select the device you are using b Select Filter Frequency Refer to Table 2 1 Filtering and Sample Rates to determine the reading rate In the Buffer Settings section you can define buffering parameters for the task With these parameters you can modify the performance of VI Logger specific
19. rules have restrictions regarding the locations where FCC Class A products can be operated Consult the FCC Web site at www fcc gov for more information FCC DOC Warnings This equipment generates and uses radio frequency energy and if not installed and used in strict accordance with the instructions in this manual and the CE marking Declaration of Conformity may cause interference to radio and television reception Classification requirements are the same for the Federal Communications Commission FCC and the Canadian Department of Communications DOC Changes or modifications not expressly approved by NI could void the user s authority to operate the equipment under the FCC Rules Class A Federal Communications Commission This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user is required to correct the interference at their own expense Canadian Department of Communications This Class A digital appar
20. systems featuring interactive graphics and state of the art user interface With LabVIEW you can quickly create front panel user interfaces giving you interactive control of the software system To specify the functionality you intuitively assemble block diagrams a natural design notation for engineers and scientists Lab VIEW has all of the same development tools and language capabilities of a standard language such as C looping and Case structures configuration management tools and compiled performance Use the NI 435x instrument driver VIs with LabVIEW What Is LabWindows CVI LabWindows CVI is an interactive ANSI C programming environment designed for automated test applications LabWindows CVI enhances traditional programming languages Use the NI 435x instrument driver functions with LabWindows CVI What Is VI Logger VI Logger equips you with the necessary software tools to define and execute a data logging task With VI Logger you can view real time data share data and browse and manage historical data Using VI Logger in Measurement amp Automation Explorer MAX with such features as event detection and calculated channels you can define advanced tasks without any programming Using LabVIEW and the VI Logger VIs you can execute a task view live data browse historical data and build logging applications using all of the advanced programming capabilities of LabVIEW Refer to the Creating a Task in VI Logger sect
21. 0 TBX 68T and CB 68T accessories If you are using NI 435x and have configured the accessory in MAX use thermocouple mode with the CJC setting of Auto to enable the software to perform cold junction compensation on all configured thermocouple channels If you are using VI Logger and have configured the accessory in MAX use the Built In option for the CJC source on the Traditional NI DAQ Legacy virtual channel Providing a constant user value If you are using NI 435x use the CJC setting of Manual on the configured thermocouple channel If you are using VI Logger use and specify the User Value option for the CJC source on the Traditional NI DAQ Legacy virtual channel Providing your own temperature sensor for CJC in which case you must complete all measurement acquisition and computational steps For example if you are using a thermistor as a CJC sensor you must complete the following steps 1 Measure the resistance of the thermistor cold junction sensor R thermistor cold junction and compute the cold junction temperature Told junctions USing the thermistor resistance temperature conversion formula 2 From this temperature of the cold junction Tooi junctions compute the equivalent thermocouple voltage V coid junction for this junction using a standard thermocouple conversion formula 2 7 NI 435x User Manual Chapter 2 Operating the NI 435x Device 3 Measure the voltage V measured and add the cold junction
22. 1 24 57 0 0013 100 000 0 0355 0 0384 0 0414 0 51 1 00 128 126 1 60 180 0 0013 50 000 0 0361 0 0390 0 0420 O45 080 1 02 121 146 162 0 0013 25 000 0 0373 0 0402 0 0432 041 0 54 074 118 128 142 0 0013 Resistance specifications assume worst case common mode voltage for the given range Specifications improve if actual common mode voltage is less than worst case Measurement accuracy is affected by source impedance Resistances gt 25 may require 1 s setting time Resistance Accuracy with I_y Add Q Add Q with Auto Zero without Auto Zero Temperature 15 C to 35 15 C to 35 Coefficient of Reading 0 C to 15 C 15 to 35 Filter Setting Filter Setting 35 C to 55 C Range W 24Hour 90 1 Year 10Hz 50Hz 60Hz 10Hz 50Hz 60Hz Reading C 15 000 0 0320 0 0349 0 0379 1 53 162 164 L63 169 171 0 0013 7 500 0 0326 0 0355 0 0385 152 157 161 163 166 169 0 0013 3 750 0 0338 0 0367 0 0397 151 153 154 162 163 164 0 0013 2 500 0 0040 0 0269 0 0209 0 03 004 005 005 006 0 06 0 0013 1 250 0 0246 0 0075 0 0305 0 03 0 04 0 04 0 05 0 05 0 06 0 0013 625 0 0258 0 0287 0 0317 0 02 002 002 0 04 0 04 0 04 0 0013 Resistance specifications assume wors
23. 106 125 160 185 0 0009 5 3 75 0 0164 0 0193 0 0223 14 30 42 120 131 140 0 0010 5 2 5 0 0066 0 0095 0 0125 5 17 24 24 32 37 0 0004 1 1 25 0 0072 0 0101 0 0131 3 12 18 22 29 33 0 0004 1 0 625 0 0084 0 0113 0 0143 2 6 11 22 24 28 0 0005 1 Voltage specifications do not include errors resulting from common mode voltages Calculate additional common mode voltage errors as common mode voltage 10 CMR specification in db 20 5 Note learn how to calculate DC voltage accuracy and if you have a thermistor other than 5 000 K refer com support and click KnowledgeBase under Option 3 Enter 1w3 NI 435x User Manual A 4 E9CHE in the search field to access the entry called Calculating the Accuracy of a Specific Resistive Sensor ni com Appendix Specifications Resistance Accuracy with lex or Igyo Add Q Add Q with Auto Zero without Auto Zero Temperature 15 C to 35 C 15 C to 35 C Coefficient of Reading 0 C to 15 C 15 C to 35 Filter Setting Filter Setting 35 C to 55 C Range W 24Hour 90Day 1 Year 10Hz 50Hz 60Hz 10Hz 50Hz 60Hz Reading C 600 000 0 0435 0 0464 0 0494 20 11 23 64 2463 2447 26 67 2737 0 0013 300 000 0 0441 0 0470 0 0500 19 82 21 80 2322 2397 2537 2637 0 0013 150 000 0 0453 0 0482 0 0512 19 54 20 16 20 67 23 77 242
24. 3 What Is LabWindows CVI teet tt rte 1 3 What Is VI Eogger n i enc et teen tb pee ded 1 3 Installing the Software detenti eher E n 1 3 Installing the Hard Wares ete rette eerte e E o e eMe 1 4 NEPXIE4351 2g nee tn tee iUe PROS 1 4 NLEPCTI A395 1 d As SRM era ee eee a eas 1 5 NI USB 4350 7 aono n eae aen D HO er 1 6 Power Considerations esee 1 6 LED Patterns aote 1 7 Nr H 1 8 Configuring the Hardware in eene rennen 1 8 Creating Task VI Logger iussis Saved tte et tup e edere rie 1 9 Using Virtual Channels with VI Logger eee 1 9 Creating Virtual Channels sess 1 9 Modifying Virtual Channels eee 1 9 Testing Virtual Channels seen 1 10 Creating and Configuring a Task essere 1 10 Selecting Channels for a VI Logger Task to Acquire and 1 11 Configuring Events for a Logging Task sess 1 12 Creating Calculated Channels eee 1 12 ACCESSO mp 1 13 National Instruments Corporation V NI 435x User Manual Contents Chapter 2 Operating the NI 435x Device Warming up the NI 435x Device eee tiet Setter 2 1 Choosing a Mea
25. 4350 4351 devices and contains information concerning device operation and programming lt gt Pg a bold italic monospace The following conventions appear 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 DIO 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 The symbol indicates that the following text applies only to a specific product a specific operating system or a specific software version 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 shipped with the product for precautions to take This icon denotes a tip which alerts you to advisory information Bold text denotes items that you must select or click in the software such as menu items and dialog box options Bold text also denotes parameter names Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a p
26. 5 uA current source on the NI PXI 4351 NI PCI 4351 and NI USB 4350 25 50 100 KQ 150 KQ 300 and 600 With the additional built in 1 mA current source on the NI PXI 4351 or NI PCI 4351 resistance mode also has 625 Q 1 2 kQ 3 75 kQ 7 5 kQ and 15 kQ as possible input ranges For the best measurement results specify the upper and lower limit values of the measurement when configuring the NI 435x When scanning multiple channels the NI 435x uses a single range which is the widest range of any channel in the scan list 3 Note Specify the limit values in engineering units appropriate to the sensor This sensor range is used to automatically set the actual hardware range Choosing a Reading Rate NI 435x User Manual The reading rate is the rate at which the NI 435x takes a new measurement This rate has a direct relationship with the digital filter built into the ADC on the NI 435x The digital filter has the characteristics shown in Figure 2 1 You can set the frequency of the first notch of this filter to 10 Hz 50 Hz or 60 Hz Setting the notch filter at one of these frequencies rejects any noise at that frequency as well as at all of its multiples 2 2 ni com Chapter 2 Operating the NI 435x Device 20 40 60 Gain dB 80 100 120 1 t 0 10 20 30 40 50 60 Frequency Hz Figure 2 1 Digital Filter Characteristics for 10 Hz Setting
27. 8 cm 5 8 x 8 4 x 1 5 in 3 U one slot PXI cPCI module 2 0x 13 0x 21 6 cm 0 8 x 5 1 x 8 5 in PCI eie eae PCI half size connector eterne 68 pin male shielded and latched Maximum Working Voltage Maximum working voltage refers to the signal voltage plus the common mode voltage Range 92 5 M seeded nets Each input should remain within 15 V of ground lt 2 5 Each input should remain within 2 5 V of ground Environmental Operating temperature 0 C to 55 Storage 20 C to 70 C Humidity ispi annnars Up to 80 RH noncondensing Maximum 2 000 m Measurement I Pollution Degree indoor use only 2 UN Caution Do not use for measurements within Categories II III or IV NI 435x User Manual A 10 ni com Appendix A Specifications Safety PCUPXI Only The NI PCI PXI 435x meets the 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 e CAN CSA C22 2 No 61010 1 3 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
28. Corporation All rights reserved Important Information Warranty The NI 4350 and NI 4351 devices are 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 techni
29. DAQ NI 435x User Manual High Precision Temperature and Voltage Meters March 2005 NATIONAL 370841B 01 INSTRUMENTS Worldwide Technical Support and Product Information ni com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 683 0100 Worldwide Offices Australia 1800 300 800 Austria 43 0 662 45 79 90 0 Belgium 32 0 2 757 00 20 Brazil 55 11 3262 3599 Canada 800 433 3488 China 86 21 6555 7838 Czech Republic 420 224 235 774 Denmark 45 45 76 26 00 Finland 385 0 9 725 725 11 France 33 0 1 48 14 24 24 Germany 49 0 89 741 31 30 India 91 80 51190000 Israel 972 0 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 7 095 783 68 51 Singapore 1800 226 5886 Slovenia 386 3 425 4200 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 200 51 51 Taiwan 886 02 2377 2222 Thailand 662 992 7519 United Kingdom 44 0 1635 523545 For further support information refer to the Technical Support and Professional Services appendix To comment on National Instruments documentation refer to the National Instruments Web site at ni com info and enter the info code feedback 2003 2005 National Instruments
30. Hz CCLO Pt 100 Q 200 0 05 0 06 0 07 0 01 0 0 12 0 13 0 14 100 0 16 0 17 0 18 300 0 23 0 24 0 26 600 0 36 0 37 0 39 RTD specifications assume that the 625 Q range 1 mA current source is used and worst case common mode voltage for this range is present Specifications improve if actual common mode voltage is less than worst case National Instruments Corporation A 3 NI 435x User Manual Appendix Specifications Thermistor Accuracy with lex or Igyo Accuracy C 15 C to 35 C 1 Year Filter Setting 10 Hz Temperature Coefficient 0 C to 15 C 50 Hz 60 Hz 35 C to 55 Thermistor C CPC 5 000 0 to 50 0 03 0 001 Thermistor accuracy is valid for all filter settings Specifications assume that the 25 range is used and worst case common mode voltage for this range is present Specifications improve if actual common mode voltage is less than worst case DC Voltage Accuracy Add uV Add uV with Auto Zero without Auto Zero Temperature 15 C to 35 15 to 35 Coefficient of Reading 0 C to 15 C 15 C 0 35 Filter Setting Filter Setting 35 C to 55 C Range Reading Volts 24 Hour 90 Day 1 Year 10Hz 50 Hz 60 Hz 10 Hz 50 Hz 60 Hz C uV C 15 0 0146 0 0175 0 0205 28 117 141 130 193 210 0 0009 5 7 5 0 0152 0 0181 0 0211 21 71
31. Institute of Standards and Technology Normal mode rejection An undesirable signal electrical noise comes from external sources such as the AC power line motors generators transformers fluorescent lights soldering irons CRT displays computers electrical storms welders radio transmitters and internal sources such as semiconductors resistors and capacitors Noise corrupts signals you are trying to send or receive Type of bipolar transistor Negative temperature coefficient Base level software that controls a computer runs programs interacts with users and communicates with installed hardware or peripheral instruments Peripheral Component Interconnect a high performance expansion bus architecture originally developed by Intel to replace ISA and EISA It is achieving widespread acceptance as a standard for PCs and workstations and offers a theoretical maximum transfer rate of 132 Mbytes s A measure of signal amplitude the difference between the highest and lowest excursions of the signal Power line cycles G 6 ni com plug and play devices port PTC PXI R reading rate resolution rms RSVDx RTD S s sigma delta sinter National Instruments Corporation G 7 Glossary Power line frequency Devices that do not require dip switches or jumpers to configure resources on the devices also called switchless devices 1 A communications connection on a computer or r
32. Programmable Open Thermocouple Detection When you measure voltage signals other than thermocouples always switch off the onboard open thermocouple detection NI 435x User Manual 2 12 ni com Chapter 2 Operating the NI 435x Device Source Impedance For best results maintain the source impedance and the lead wire resistance of the signal at less than 100 If either of these is greater than 25 you should measure the same channel for up to 1s then switch to another channel to achieve the specified accuracy AC Noise Effects The NI 435x rejects AC voltages as specified in Appendix A Specifications However if the amplitudes of the AC voltages are large compared to the DC voltages or if the peak value AC plus DC of the measured voltage is outside the input range the NI 435x may exhibit additional errors To minimize these errors keep the signal source the NI 435x and its accessories away from strong AC magnetic sources and minimize the area of the loop formed by the wires that connect the signal source with the accessories Choosing the notch filter frequency of 10 Hz provides the best AC noise rejection If the peak value of the measured voltage is likely to exceed the selected input range select the next higher input range Thermal EMF Thermoelectric potentials or thermal EMFs are voltages generated at the junctions of dissimilar metals and are functions of temperature Thermal EMFs in the source generating the signa
33. R 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 Compliance Compliance with FCC Canada Radio Frequency Interference Regulations Determining FCC Class The Federal Communications Commission FCC has rules to protect wireless communications from interference The FCC places digital electronics into two classes These classes are known as Class A for use in industrial commercial locations only or Class B for use in residential or commercial locations All National Instruments NI products are FCC Class A products Depending on where it is operated this Class A product could be subject to restrictions in the FCC rules In Canada the Department of Communications DOC of Industry Canada regulates wireless interference in much the same way Digital electronics emit weak signals during normal operation that can affect radio television or other wireless products All Class A products display a simple warning statement of one paragraph in length regarding interference and undesired operation The FCC
34. V 1 25 V 2 5 V 3 75 V 7 5 V and 15 V The NI PXI PCI 4351 has six additional ranges of 625 Q 1 25 kQ 2 5 kQ 3 75 kQ 7 5 and 15 with the 1 mA current source 2 16 ni com Chapter 2 Operating the NI 435x Device The NI 435x can measure resistances to its specified accuracy as long as the voltage across the resistors is within the selected input range specified above To get the best resolution noise rejection and accuracy choose the smallest range in which the signals can be accommodated Make sure that each signal input to CH and CH is within the input common mode limits of its input range and that the total resistance connected to the current excitation source does not exceed its maximum load To determine the most suitable input range for the application estimate the voltage developed across the resistor by following the procedure outlined in Figures 2 7 and 2 8 Estimate the common mode voltage at the inputs and verify that the range you select can handle that common mode voltage Refer to the Maximum Working Voltage section of Appendix A Specifications for the maximum voltage per range To determine if the current excitation source can handle the load you are connecting to it calculate the total load by adding the resistance value of all resistors RTDs and thermistors connected in series to the current excitation Use the maximum resistance value that the RTDs and thermistors will reach in your measu
35. a 0 6 Q error For a platinum RTD with 0 00385 this error equals 0 6 2 0 385 1 6 C error By connecting the RTD in 4 wire configuration this error is no longer present in the measurement Alternatively you can use a 3 wire RTD configuration as shown in Figures 2 5 and 2 6 Note In the 3 wire connections shown in Figure 2 6 the effects of the lead wire resistance cancel out as long as all three wires have the same lead resistance while in the connections shown in Figure 2 5 the resistance of only one lead adds error to the measurement NI 435x User Manual You can use the same current excitation for several resistors as long as you do not exceed the maximum load and are within the common mode voltage specification Refer to the Input Ranges section in the Connecting Resistors section for more information about connection precautions and for examples of how you can use different transducers connected to analog channels in the same measurement setup 2 22 ni com Chapter 2 Operating the NI 435x Device 5 Note For best results use the 1 mA current source when using NI 4351 with RTDs with resistances below kQ For resistances above 1 kQ or with the NI 4350 use the 25 uA current source to avoid self heating Refer to the Self Heating section for further details Introduction to Thermistors A thermistor is a piece of semiconductor made from metal oxides pressed into a small bead disk wafer or oth
36. ally if you are trying to log data at a high rate 1 10 ni com Chapter 1 Introduction Tip You cannot log data from more than one NI DAQ device per task However you can define one task for each device and can run more than one task at the same time ag 6 Inthe Logging Conditions section you can control datalogging using one of the digital lines Refer to the Using Digital Lines to Control Datalogging section of the VI Logger Help by selecting Help Help Topics VI Logger VI Logger in MAX ik Note The NI 435x hardware does not support digital or analog triggering By default the Start acquisition on trigger checkbox is unchecked If you select the checkbox you receive an error when you start the task this error indicates that triggering is not supported Refer to step 6 above for alternative software triggering Selecting Channels for a VI Logger Task to Acquire and Log Data For each VI Logger task you configure you can select which specific channels acquire and log data within that task Complete the following steps to set up the channels that acquire and log data 1 With a VI Logger Task selected click the Virtual Channels tab to open the Virtual Channels view 2 Right click the Events column heading and select Events to enable or disable the information displayed in the table Refer to the Measurement amp Automation Explorer Help for VI Logger by selecting Help Help Topics VI Logger VI Logger for more inf
37. annel clock CMOS CMR CompactPCI coupling CPU D DAQ dB DC DC coupled device DGND DIO National Instruments Corporation G 3 Glossary Pin or wire lead to which you apply or from which you read the analog or digital signal Analog signals can be single ended or differential For digital signals you group channels to form ports Ports usually consist of either four or eight digital channels Hardware component that controls timing for reading from or writing to groups Complimentary metal oxide semiconductor Common mode rejection Refers to the core specification defined by the PCI Industrial Computer Manufacturer s Group PICMG The manner in which a signal is connected from one location to another Central processing unit Data acquisition 1 Collecting and measuring electrical signals from sensors transducers and test probes or fixtures and inputting them to a computer for processing 2 Collecting and measuring the same kinds of electrical signals with A D and or DIO devices plugged into a computer and possibly generating control signals with D A and or DIO devices in the same computer Decibel the unit for expressing a logarithmic measure of the ratio of two signal levels dB 20 log V V for signals in volts Direct current Allowing the transmission of both AC and DC signals A plug in data acquisition product card or pad that can contain multiple channels and c
38. ature curve figure 2 24 types of thermistors 2 23 National Instruments Corporation 1 5 Index thermocouples for measuring temperature accuracy specifications table A 1 cold junction effect figure 2 7 connecting 2 8 input ranges 2 8 optimizing measurements AC noise effect 2 10 auto zero method 2 9 programmable ground referencing 2 9 programmable open thermocouple detection 2 10 thermal EMF 2 11 overview 2 6 training and certification NI resources C 1 troubleshooting NI resources C 1 volts measurement mode range selection 2 2 W Web resources C 1 NI 435x User Manual
39. atus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet appareil num rique de la classe A respecte toutes les exigences du R glement sur le mat riel brouilleur du Canada Compliance with EU Directives Users in the European Union EU should refer to the Declaration of Conformity DoC for information pertaining to the CE marking 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 The marking Declaration of Conformity contains important supplementary information and instructions for the user or installer Contents About This Manual COMVENELONS s EE E spelen cade E cubase ix Related Documentation e eter teg pn e e tp epi eris X Example8 ete rtt Re ondess e ee eai UU ee mU ne OVER T X Chapter 1 Introduction About the NI 435x High Precision DAQ Devices se 1 1 Using PXI with CompactPCT eit tet eee tein Rer renta ente Een terea 1 2 Configuration eee dec ER Rt S CR d CH e de ted iet 1 2 Software Options for the NI 435 enne ener 1 2 What Is the NI 435x Instrument Driver esses 1 2 What Is Lab VIEW incu ete ard e Ree e tee bep aped 1
40. cal or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation
41. cy Time s 0 1 0 3 0 01 0 5 0 0015 2 4 0 001 3 0 0004 7 Excitation Note The exact value of the excitation current is stored on the hardware NI DAQ uses this value when taking resistance measurements Number of channels 2 Parameter Igx or Igxo Igxi Level 25 uA 1 mA Maximum Load 600 kQ 15 KQ Resistance Temperature 15 ppm C 15 ppm C Coefficient 1 The 1 mA excitation level is only available on the NI 4351 NI 435x User Manual A 8 ni com Appendix Specifications Digital 1 0 and Alarm Outputs Number of lines 8 Compatibility eene TTL DIO 0 3 7 Level Minimum Maximum Input low voltage 0 0 V 0 8 V Input high voltage 2 0 V 5 0 V Vcc Input low current Vi 5 V 10 uA Input high current Vin 5 V 10 uA Output low voltage 8 mA 0 4 V Output high voltage I 8 mA 3 8V Power on state Tristate Data transfers ces Programmed I O Bus Interface Type Slave plug and play USB aon High power USB powered peripheral 500 mA PX Des tract 480 mA at 5 V IRI 480 mA at 5 V Power available at I O connector 14 6 V to 45 2 V 1 A PXI PCD 44 6 V to 5 2 V 50 mA USB National Instruments Corporation A 9 NI 435x User Manual Appendix Specifications Physical Dimensions LE 14 6 x 21 3 x 3
42. e measurement method is to use a 4 wire connection where one pair of wires carries the excitation current and the other pair of wires senses the voltage across the resistor Because the input impedance of the channel CH and CH is very high practically no current flows through the sensing wires the lead resistance error of and is negligible Figure 2 4 illustrates this configuration 3 Note To minimize the error due to lead resistance connect the voltage sense terminals CH and CH as close as possible to the resistor under test Ru 4 0 lex lexo OF lexis Rie CH Z RTD CH Ris WW a O lex Igxo or lexi Ria Figure 2 4 4 Wire Measurement where an RTD is the Resistor Under Test Alternatively you can use a 3 wire connection Figure 2 5 shows a 3 wire resistor configuration with a current source In this configuration the resistance of only one lead adds error to the measurement lex lexo OF 1 Ru NN o CH Z RTD ew CH Rie NN a O lex lgxo or lexi Ris Figure 2 5 3 Wire Measurement where an RTD is the Resistor Under Test Another variation of the 3 wire configuration is shown in Figure 2 6 In this configuration the effects of the same lead resistance cancel out as long as National Instruments Corporation 2 15 NI 435x User Manual Chapter 2 Operating the NI 435x Device all three w
43. e technical resources or other project challenges National Instruments Alliance Partner members can help To learn more call your local NI office or visit ni com alliance Declaration of Conformity DoC A DoC is our claim of compliance with the Council of the European Communities using the manufacturer s declaration of conformity This system affords the user protection for electronic compatibility EMC and product safety You can obtain the DoC for your product by visiting ni com certification C 1 NI 435x User Manual Appendix Technical Support and Professional Services e Calibration Certificate If your product supports calibration you can obtain the calibration certificate for your product at ni com calibration If you searched ni com and could not find the answers you need contact your local office or NI corporate headquarters Phone numbers for our worldwide offices are listed at the front of this manual You also can visit the Worldwide Offices section of ni com niglobal to access the branch office Web sites which provide up to date contact information support phone numbers email addresses and current events NI 435x User Manual C 2 ni com Glossary Symbol Prefix Value pico 10 12 10 u micro 10 6 m milli 10 3 kilo 103 M mega 106 G giga 10 T tera 102 Numbers Symbols g Degree Negative of or minus Q Ohm P
44. e NI USB 4350 powers off any data acquisition in progress is aborted and the data is lost The host computer has the ability to go into a power saving suspend mode and during this time the NI USB 4350 also can either go into a low power mode or remain in a fully powered static state This low power mode is important if you are using a laptop or if power consumption is a concern In the powered static state of the NI USB 4350 all digital outputs are static at a fixed voltage Note By default the NI USB 4350 remains fully powered during suspend mode To change the settings that determine the behavior of the NI USB 4350 during suspend mode refer to one of the following locations e The Set_DAQ_Device_Info section of the Traditional NI DAQ Legacy Function Reference Help located at Start Programs National Instruments NI DA Q Traditional NI DAQ Legacy Function Reference Help The Set DAQ Device Information Device Setting VI section of the LabVIEW Help located at Start Programs National Instruments Lab VIEW 7 x VI Function amp How To Help LED Patterns If the LED comes on after the NI USB 4350 is connected to the computer the device is functioning properly If the LED remains off or blinks refer to Table 1 1 Table 1 1 LED State Patterns for the NI USB 4350 States LED State Description On Configured state The NI USB 4350 is configured Off Off or in the low power The NI USB 4350 is
45. e current source helps prevent any appreciable error due to self heating RTDs are relatively immune to the problem of self heating because their resistance is relatively small such as 100 Q at 0 C Also the amount of self heating depends significantly on the medium in which the RTD is immersed An RTD can self heat up to 100 times higher in still air than in moving water The self heating in RTDs that is due to the built in 25 uA is negligible When using 1 mA excitation current a 100 RTD dissipates as follows DR 1 mA x 100 Q 20 1 mW If this RTD has a dissipation constant of 5 mW C the RTD self heats by 0 02 C AC Noise Effects The NI 435x rejects AC noise as specified in NMR in Appendix A Specifications However if the amplitudes of the AC noise are large compared to the DC signal or if the peak value AC plus DC of the National Instruments Corporation 2 27 NI 435x User Manual Chapter 2 Operating the NI 435x Device measured signal is outside the input range the NI 435x may exhibit additional errors To minimize these errors keep the signal source the NI 435x and its accessory away from strong AC magnetic sources and minimize the area of the loop formed by the wires connecting the signal source with the accessory Choosing the notch filter frequency of 10 Hz provides the best AC noise rejection If the peak value of the measured voltage is likely to exceed the selected input range select the next higher
46. e resistances can be in the form of RTDs thermistors or any other resistor The calibrated value of the current source is stored onboard and NI 435x uses this precise value in its computations Connecting Resistors NI 435x User Manual To measure resistance you must pass current through the device and measure the resulting voltage NI 435x returns resistance measurements by dividing the measured voltage by the calibrated value of the current source stored onboard However any resistance in the lead wires that connect the measurement system to the resistor adds errors to the readings Figure 2 3 shows an example of an RTD connected to the NI 435x accessory using two leads The NI 435x accessory also supplies a constant current source Igy to excite the resistor This type of connection is known as a 2 wire connection The voltage measured corresponds to the voltage drops across the resistor under test and across the two lead resistances 2 lex OF Igi RL VW O CH 2 RTD VW O CH EE en OF lgxi Figure 2 3 2 Wire Measurement where RTD is the Resistor Under Test For example a lead resistance of 0 3 Q in each wire adds a 0 6 Q error to the resistance measurement If you are using lead lengths greater than 10 ft you may need to compensate for this error To compensate for lead resistance the preferred 2 14 ni com Chapter 2 Operating the NI 435x Devic
47. ecifications A 10 power requirements A 9 programmable ground referencing See ground referencing programmable programmable open thermocouple detection See open thermocouple detection programmable programming examples NI resources C 1 PXI using with CompactPCI 1 2 NI 435x User Manual Index R range selection for measurement mode 2 2 reading rate selection determining reading rate per channel note 2 3 filtering and sample rates table 2 4 reference junction 2 6 related documentation x resistance measurement connecting resistors multiple transducer connections to analog channels figures 2 18 preventing safety hazards caution 2 17 input ranges 2 16 optimizing AC noise effects 2 27 auto zero method 2 25 connecting to external circuits 2 26 guidelines for resistance measurement table 2 26 programmable ground referencing 2 26 programmable open thermocouple detection 2 26 self heating 2 27 thermal EMF 2 28 two wire three wire and four wire measurements 2 26 RTDs connecting 2 14 relationship of resistance and temperature 2 20 thermistors connecting 2 25 resistance temperature characteristics 2 24 RTDs accuracy specifications tables A 3 Callendar Van Dusen coefficients table 2 22 NI 435x User Manual l 4 connecting four wire RTD measurement figure 2 15 three wire RTD measurement figure 2 15 two wire RTD measurement figure 2 14 definition 2 20 measuring
48. emote controller 2 A digital port consisting of four or eight lines of digital input and or output Positive temperature coefficient A rugged open system for modular instrumentation based on CompactPCI with special mechanical electrical and software features The rate in hertz at which each sample is updated The smallest signal increment that can be detected by a measurement system Resolution can be expressed in bits in proportions or in percent of full scale For example a system has 24 bit resolution one part in 224 16 777 216 resolution and 5 96 x 10 996 of full scale Root mean square the square root of the average value of the square of the instantaneous signal amplitudes a measure of signal amplitude Reserved Resistance temperature detector a metallic probe that measures temperature based upon its resistance Second Sample Samples per second used to express the rate at which an NI 435x samples an analog signal Technology used for analog to digital conversion To cause to become a coherent mass by heating without melting NI 435x User Manual Glossary system noise T thermistor thermocouple TTL update update rate USB VI virtual channels NI 435x User Manual A measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded A semiconductor sensor that produces a repeatable change in electrical resistance as a functi
49. en thermocouple detection 2 5 range selection 2 2 reading rate selection 2 2 resistance measurement input ranges 2 16 optimizing measurements 2 25 RTDs for measuring temperature connecting 2 14 optimizing measurements 2 25 relationship of resistance and temperature 2 20 signal sources floating signal source 2 4 ground referenced signal source 2 4 thermistors for measuring temperature connecting thermistors 2 25 optimizing measurements 2 25 resistance temperature characteristics 2 24 thermocouples for measuring temperature connecting thermocouple 2 8 input ranges 2 8 optimizing measurements 2 8 optimizing measurements DC voltage AC noise effects 2 13 auto zero method 2 12 programmable ground referencing 2 12 programmable open thermocouple detection 2 12 National Instruments Corporation 1 3 Index source impedance 2 13 thermal EMF 2 13 RTDs thermistors and resistors AC noise effects 2 27 auto zero method 2 25 connecting to external circuits 2 26 guidelines for resistance measurement table 2 26 programmable ground referencing 2 26 programmable open thermocouple detection 2 26 self heating 2 27 themal EMF 2 28 two wire three wire and four wire measurements 2 26 thermocouples AC noise effects 2 10 auto zero method 2 9 programmable ground referencing 2 9 programmable open thermocouple detection 2 10 thermal EMF 2 11 optional equipment 1 13 P physical sp
50. er shape which is 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 and positive temperature coefficient PTC thermistors An NTC thermistor is one whose resistance decreases with increasing temperature A PTC thermistor is one whose resistance increases with increasing temperature NTC thermistors are much more commonly used than PTC thermistors especially for temperature measurement applications A main advantage of thermistors for temperature measurement is their 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 or more In comparison 100 Q platinum RTD has a sensitivity of only 0 4 Q C The small size of the thermistor bead also yields a fast response to temperature changes Another advantage of the thermistor is its relatively high resistance Thermistors are available with base resistances at 25 ranging from hundreds to millions of ohms This high resistance diminishes 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 4 wire or 3 wire connections to reduce errors ca
51. ercent Plus or minus Positive of or plus 45V 5 V output signal A Amperes AC Alternating current National Instruments Corporation G 1 NI 435x User Manual Glossary AC coupled ADC AGND ANSI AT bus attenuation Auto Zeroing AWG b B bandwidth bipolar buffer bus CH NI 435x User Manual Allowing the transmission of AC signals while blocking DC signals Analog to digital converter an electronic device that converts an analog voltage to a digital number Analog ground signal American National Standards Institute See bus Decreasing the amplitude of a signal The process of removing an offset error from a measurement American Wire Gauge Bit one binary digit either 0 or 1 Byte eight related bits of data an eight bit binary number Also used to denote the amount of memory required to store one byte of data The range of frequencies present in a signal or the range of frequencies to which a measuring device can respond A signal range that includes both positive and negative values for example 5 V to 5 V Temporary storage for acquired or generated data software The group of signals that interconnect individual circuitry in a computer Typically a bus is the expansion vehicle to which I O or other instruments are connected Examples of PC buses are the AT bus also known as the ISA bus and the PCI bus Celsius Channel G 2 ni com ch
52. es C 1 excitation specifications A 8 external circuits connecting to 2 26 F floating signal source 2 4 G ground referenced signal source 2 4 ground referencing programmable optimizing measurements DC voltage measurement 2 12 RTDs thermistors and resistors 2 26 thermocouples 2 9 purpose and use 2 5 settings table 2 5 H help technical support C 1 input ranges DC voltage measurement 2 11 resistance measurement 2 16 thermocouples 2 8 instrument drivers NI resources C 1 K KnowledgeBase C 1 NI 435x User Manual L LEDs for NI 4350 USB patterns table 1 7 measurement mode choosing 2 1 National Instruments support and services C 1 NI 4350 USB LEDs patterns table 1 7 NI 435x examples x NI 435x instruments See also operation of NI 435x instruments optional equipment 1 13 overview 1 1 using PXI with CompactPCI 1 2 NI support and services C 1 noise effects AC See noise effects minimizing 0 open thermocouple detection programmable optimizing measurements DC voltage measurement 2 12 RTDs thermistors and resistors 2 26 thermocouples 2 10 settings table 2 6 ni com operation of NI 435x instruments current source 2 14 DC voltage measurement connecting DC voltage signal 2 11 input ranges 2 11 optimizing measurements 2 12 digital inputs and outputs 2 28 measurement mode selection 2 1 programmable ground referencing 2 5 programmable op
53. hannel 1 Click the Calculated Channels tab to display the Calculated Channels view Click Create channel The Math Expression Editor dialog box appears where you can define a math channel In the Channel Settings section in the Name field enter an appropriate name for the math channel In the Units field enter the appropriate unit type In the Minimum and Maximum fields enter a range of units that applies to the math channel In the Formula Settings section in the Formula field click the down arrow and select one of four formulas to apply to the math channel Op By C A linear combination formula in fields A Channel X Operation B Channel Y and C with the appropriate values x y A measurement of noise db power base 10 Select the channels you want for Channel X and Channel Y fields e dBVx A single channel noise measurement Select the channel you want for the Channel X field e User Defined A formula that you create Click OK 1 12 ni com Chapter 1 Introduction Accessories NI offers a variety of products to use with the NI 435x including cables connector blocks terminal blocks and other accessories as follows e Isothermal terminal blocks TBX 68T CB 68T and TC 2190 e Terminal blocks TBX 68 e Shielded and ribbon cables For more information about these products contact NI or search for NI PXI 4351 NI PCI 4351 or NI USB 4350 at ni com catalog Na
54. he trigger condition and start the analog acquisition after receiving the trigger NI 435x User Manual 2 26 ni com Chapter 2 Operating the NI 435x Device Connecting the Digital Input and Output All NI 435x accessories are designed to be used for DIO Refer to the accessory installation guide for instructions on how to connect the DIO lines Figure 2 11 shows examples of how to connect DIO lines for various applications such as controlling an LED monitoring a TTL compatible or CMOS compatible signal monitoring a low voltage switch and monitoring a low voltage transistor For the NI 435x for PXI PCI and USB you can use the TBX 68T revision C or later and the CB 68T to connect to digital signal conditioning accessories with optocouplers solid state relays and electromechanical relays such as the SC 2061 SC 2062 SC 2063 SSR Series and ER Series 45V LED e gt WW DIOO configured as an output TTL or CMOS DIO1 configured as an input Ro e WW DIO2 configured as an input sw Rs WV O DIOS configured as an input NPN Transistor 9 R4 O DIOS configured as an output o DGND Figure 2 11 Examples of DIO Applications Caution To prevent possible safety hazards the voltage applied to the digital I O lines should never be outside 0 5 V and 5 5 V with respect to DGND National Instruments Corporation 2 29 NI 435x User Manual
55. ibit additional errors To minimize these errors keep the thermocouples the NI 435x and its accessories away from strong AC magnetic sources and minimize the area of the loop formed by the thermocouple wires connected to the accessory Choose the notch filter frequency of 10 Hz for the best AC noise rejection If the peak value of the measured voltage is likely to exceed the selected input range select the next higher input range 2 10 ni com Chapter 2 Operating the NI 435x Device Thermal EMF When using thermocouples any thermal EMFs introduce error other than those at the hot junction where the thermocouple measures the test point temperature and at the cold junction on the accessory To minimize thermal EMFs use wires made of the same material as the thermocouple when extending the length of the thermocouple Also minimize temperature gradients in the space enclosing the thermocouples the NI 435x and its accessories Measuring DC Voltage Connecting the DC Voltage Signal The NI 435x accessories the TBX 68T CB 68T TBX 68 and TC 2190 for the NI 435x for PXI PCI and USB are designed to be used with any DC voltage signal Consult the accessory installation guide for instructions on how to connect the voltage signals The NI 435x analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered on and 17 VDC when the NI 435x is powered off Never apply voltages above these levels
56. ications Thermocouple Accuracy Error C 0 C to 15 C 15 C to 35 C 1 Year 35 to 55 Filter Setting Temperature Accessory Coefficient Error Thermocouple Type 10 Hz 50 Hz 60 Hz 100 0 53 0 61 0 74 0 02 0 25 0 0 42 0 49 0 59 760 0 42 0 47 0 55 K 100 0 60 0 72 0 89 0 03 0 27 0 0 45 0 54 0 67 1 000 0 60 0 69 0 81 1 372 0 74 0 84 0 99 National Instruments Corporation 1 NI 435x User Manual Appendix Specifications Error C 0 to 15 C 15 C to 35 C 1 Year 35 C to 55 C Filter Setting Temperature Accessory Coefficient Error Thermocouple Type 10 Hz 50 Hz 60 Hz 100 0 68 0 84 1 08 0 03 0 26 0 0 54 0 67 0 86 400 0 42 0 51 0 65 1 300 0 57 0 66 0 80 E 100 0 55 0 62 0 74 0 02 0 28 0 0 41 0 46 0 55 500 0 35 0 40 0 46 1 000 0 46 0 50 0 57 T 150 0 81 0 96 1 17 0 03 0 36 0 0 46 0 55 0 68 400 0 33 0 39 0 47 R 250 0 82 1 16 1 65 0 06 0 12 1 000 0 72 0 99 1 37 1 767 0 91 1 19 1 60 250 0 91 1 28 1 83 0 07 0 13 1 000 0 77 1 05 147 1 767 0 96 1 27 1 72 B 600 1 08 1 64 2 47 0 11 0 00 1 000 0 76 1 14 1 69 1 820 0 74 1 05 1 50 Thermocouple measurement specifications include cold junction compensation error with sensor between 15 C and 35 C isothermal accuracy and system
57. ion of this manual for information on using VI Logger Installing the Software Refer to the NI 435x Getting Started Guide that ships with the NI 435x hardware or at ni com manuals for information about installing NI 435x instrument driver software and VI Logger software National Instruments Corporation 1 8 NI 435x User Manual Chapter 1 Introduction Installing the Hardware To install the NI PXI 4351 NI PCI 4351 or NI USB 4350 hardware complete the steps of the appropriate procedure as follows UN Cautions Follow proper ESD precautions to ensure you are grounded before installing the hardware Refer to Appendix A Specifications for important safety and compliance information For safety information that is relevant to the NI 435x devices refer to the Read Me First Safety and Radio Frequency Interference document in the NI 435x shipping kit or at ni com manuals NI PXI 4351 Complete the following steps and refer to Figure 1 1 to install the NI PXI 4351 1 PXI Chassis 5 Front Panel Mounting Screws 2 PXI System Controller 6 Module Guides 3 NI PXI 4351 7 Power Switch 4 Injector Ejector Handle Figure 1 1 Installing the NI PXI 4351 1 Power off and unplug the PXI chassis NI 435x User Manual 1 4 ni com Chapter 1 Introduction Caution Before removing equipment covers or connecting or disconnecting signal wires refer to the Read Me First Safety and Radio Frequency
58. ires have the same lead resistance However it uses two input channels per resistor while the previous configurations use only one lex OF Rus WW CHn 2 RTD o CHn Rie O CH 41 ANN e CHp 4 Ris L o OF lex1 Roun n RcH n 1 if Ru Riz Ris Figure 2 6 3 Wire Measurement and Lead Wire Resistance Compensation where an RTD is the Resistor Under Test ER Note For best results use the 1 mA current source when using the NI 4351 with RTDs or resistors with resistances below 1 KQ For resistances above 1 or with the NI 4350 use the 25 uA current source to avoid self heating Refer to the Self Heating section for further details Input Ranges NI 435x User Manual You can use the same current excitation for several resistors as long as you do not exceed the maximum load and are within the common mode voltage specification listed in Appendix A Specifications Refer to Figures 2 7 and 2 8 for examples of how you can use different transducers connected to analog channels in the same measurement setup With the 25 uA current source the NI PXI 4351 NI PCI 4351 and NI USB 4350 have six ranges for resistance measurements 25 KQ 50 KQ 100 150 300 and 600 These ranges correspond to the six input ranges available for measuring DC voltages developed across resistors 625 m
59. ith the TBX 68 NI 435x USB PXI PCI TBX 68 Signal Name Screw Terminal 68 CH0 34 CH1 33 CH1 66 CH2 65 CH2 31 CH3 30 CH3 63 CH4 62 CH4 29 CH5 28 CH5 61 CH6 60 CH6 26 CH7 25 National Instruments Corporation B 1 NI 435x User Manual Appendix Signal Connections Table B 1 Using the NI 435x USB PXI PCI with the TBX 68 Continued NI 435x USB PXI PCI TBX 68 Signal Name Screw Terminal CH7 58 CH8 57 CH8 23 CH9 22 CH9 55 CH10 54 CH10 21 CH11 19 CH11 53 CH12 52 CH12 18 CH13 17 CH13 50 CH14 49 CH14 15 15 13 CH15 46 lexo NI 4351 12 lex Igxo NI 4351 45 lexis NI 4351 only 44 Igxi NI 4351 only 10 DIOO 7 DIOI 6 DIO2 5 DIO3 4 NI 435x User Manual B 2 ni com Appendix Signal Connections Table B 1 Using the NI 435x USB PXI PCI with the TBX 68 Continued NI 435x USB PXI PCI TBX 68 Signal Name Screw Terminal DIO4 37 DIOS 3 DIO6 2 DIO7 1 5V 8t DGND 35 36 38 39 40 41 42 AGND 9 10 11 14 16 20 24 27 32 43 44 47 48 51 56 59 64 67 Screw terminals 10 and 44 are AGND on the NI 4350 only and are not labeled AGND on revision C or later of the TBX 68T The current available may be limited to less than 50
60. jected Reading Rate Reading Rate Setting Hz Hz Rate PLC Hz Hz readings s readings s 10 50 or 60 slow 5 50 10 50 60 10 2 8 1 4 6 60 400 40 400 50 50 fast 1 50 50 and 400 50 8 8 2 1 8 400 60 60 fast 1 60 60 60 9 7 2 1 Powerline frequency t Number of powerline cycles used for filtering To determine the reading rate per channel divide this value by the number of channels in the scan For resistance ranges of 50 and higher 5 Knowing the Signal Source Note These rates were obtained without Auto Zeroing and cold junction compensation For accurate measurements you must determine whether the signal source is floating or ground referenced Floating Signal Source A floating signal source is one that is not connected in any way to the building ground system but has an isolated ground reference point Examples of floating signal sources are thermocouples with ungrounded junctions and outputs of transformers batteries battery powered devices optical isolators and isolation amplifiers Ground Referenced Signal Source A ground referenced signal source is one that is connected in some way to the building system ground Therefore it is already connected to a ground point with respect to the NI 435x assuming that the computer is plugged into the same power system Examples of ground referenced signal sources include the following Thermocou
61. l you need to first create the virtual channel and test it Creating Virtual Channels Complete the following steps to create the traditional virtual channels to use in a data logging task 1 Launch the Measurement amp Automation icon 2 Inthe MAX configuration tree right click Data Neighborhood and select Create New from the pop up menu 3 The Create New wizard opens Select Traditional NI DAQ Legacy Virtual Channel and follow the wizard instructions to create a new virtual channel Modifying Virtual Channels Complete the following steps to modify a virtual channel 1 In the configuration tree of MAX right click a virtual channel under Data Neighborhood 2 Select Properties 3 Make any modifications necessary in the Configuration dialog box that appears 4 Click OK when you are finished 3 Note Click the Advanced button to view and change additional channel properties including Auto zero Mode Notch Filter Frequency Open Thermocouple Detection and Ground Referencing National Instruments Corporation 1 9 NI 435x User Manual Chapter 1 Introduction Testing Virtual Channels The Virtual Channel Test Panels show actual readings so you can directly control the different channels you have configured Complete the following steps to test the virtual channels 1 In the configuration tree of MAX right click a virtual channel under Data Neighborhood Select Test View the readings and change any
62. l can introduce errors in measurements that change with variations in temperature To minimize thermal EMFs use copper wires to connect the signal to the NI 435x accessory Avoid using dissimilar metal wires in connections Also minimize temperature gradients in the space enclosing the signal source the NI 435x and its accessories Measuring Resistance and Measuring Temperature with RTDs and Thermistors RTDs and thermistors are essentially resistors whose resistance varies with temperature Therefore measurement techniques for RTDs thermistors and resistors are quite similar All techniques involve exciting the resistor with a current or a voltage source and measuring the resulting voltage or current respectively developed in the resistor The NI 435x accessories the TBX 68T CB 68T and TBX 68 for the NI 435x for PXI PCI and USB are designed to be used with RTDs National Instruments Corporation 2 13 NI 435x User Manual Chapter 2 Operating the NI 435x Device thermistors and resistors Consult the accessory installation guide for instructions on how to configure the terminal block Using the Current Source The NI PXI 4351 NI PCI 4351 and NI USB 4350 feature a 25 WA precision current source which supplies excitation for a total maximum load resistance of 600 The NI PXI PCI 4351 has an additional precision current source which supplies 1 mA excitation for a total maximum load resistance of 15 KQ Thes
63. laceholder 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 National Instruments Corporation ix NI 435x User Manual About This Manual NI 435x NI 435x for PXI PCI and USB NI PCI 4351 NI PXI 4351 NI USB 4350 Refers to all NI 4350 and NI 4351 devices Refers to the NI 4350 and NI 4351 devices by form factor Refers to the NI 4351 for PCI Refers to the NI 4351 for PXI Refers to the NI 4350 for USB Software sometimes refers to this device as the NI DAQPad 4350 Related Documentation Examples This manual is one piece of the NI 435x documentation set Refer to the following documents at com manuals for additional information that is relevant to the NI 435x devices e Read Me First Safety and Radio Frequency Interference e Refer to the following software documentation at Start Programs National Instruments NI 435x Documentation NI 435x LabVIEW Reference Help NI 435x C C CVI VB Help e Accessory installation guides or manuals If you are using accessory products read the terminal block adapter and cable assembly installation guides They explain how
64. nd thermocouple modes Using Programmable Open Thermocouple Detection The NI 435x devices have software programmable open thermocouple detection on every channel which you can use to detect an open or broken thermocouple This feature connects to 42 5 V through a 10 MO resistor This resistor acts as a pull up resistor and consequently the voltage between and CH rises rapidly above 100 mV if the thermocouple breaks open All thermocouples functioning under normal conditions generate a voltage of less than 100 mV even at very high temperatures You can detect this voltage level in software and conclude that the thermocouple is open National Instruments Corporation 2 5 NI 435x User Manual Chapter 2 Operating the NI 435x Device To understand how setting open thermocouple detection affects the accuracy of measurements refer to the Programmable Open Thermocouple Detection section You can set open thermocouple detection on a channel by channel basis Table 2 3 summarizes the settings you should use for open thermocouple detection Table 2 3 Using Programmable Open Thermocouple Detection Programmable Open Thermocouple Signal Source Detection Thermocouples On or Off Voltage signal sources other than Off thermocouples RTDs thermistors and resistors connected Off to the built in current source Note The default setting for programmable open thermocouple detection in volts and
65. noise The specifications assume that the 0 625 V range is used and that ground referencing and open thermocouple detection are enabled for a floating thermocouple Specifications improve with ground referencing enabled and open thermocouple detection disabled for a floating thermocouple The specifications also assume that the cold junction sensor is between 15 C and 35 C Add when the thermocouple accessory and the NI 435x are outside of the 15 C to 35 C temperature range Add when the thermocouple accessory is outside of the 15 C to 35 C temperature range NI 435x User Manual A 2 ni com Appendix Specifications RTD Accuracy with lex or lexo Error C 0 C to 15 C 15 C to 35 C 1 Year 35 C to 55 Filter Setting Temperature Coefficient RTD C 10 Hz 50 Hz 60 Hz Pt 100 Q 200 1 00 1 33 1 81 0 01 0 1 14 1 49 2 00 100 1 22 1 58 2 10 300 1 38 1 76 2 32 600 1 66 2 08 2 69 RTD specifications assume that the 25 KQ 25 pA current source range is used and worst case common mode voltage for this range is present Specifications improve if actual common mode voltage is less than worst case Specifications improve for a 1 000 RTD RTD Accuracy with Igyi Error 0 C to 15 C 15 C to 35 C 1 Year 35 C to 55 C Filter Setting Temperature Coefficient RTD SC 10 Hz 50 Hz 60
66. nt source return terminals Tex lexo and Igx are tied to 2 5 V through internal circuits This 2 5 V causes any resistor excited by the current source to be ground referenced Otherwise the leakage current flowing into the resistor can cause erroneous measurements for all channels that use the current source Programmable Open Thermocouple Detection Always switch off open thermocouple detection on the channel connected to a resistor Otherwise the leakage current flowing into the resistor can cause erroneous measurements for all channels that use the current source Connecting to External Circuits Refer to Figures 2 7 and 2 8 for examples of how different transducers connect to analog channels in the same measurement setup To measure the value of a resistor accurately make sure the resistor is not electrically connected to any other circuits Erroneous or misleading readings can result if the resistor you are measuring is electrically connected to external circuits that supply voltages or currents or if the measured resistor is connected to external circuits that change the effective resistance 2 Wire 3 Wire and 4 Wire Measurements The Connecting Resistors section discusses whether to use 2 wire 3 wire or 4 wire setups and applies to any resistance measurement Choose the appropriate measurement technique for the application as shown in Table 2 5 Table 2 5 Guidelines for Resistance Measurements Measu
67. ocouple Rejthermistor x 25 uA o CH1 Detection Off Cold Junction Thermistor on Accessory F Open Thermocouple oCHo Detection Off Voltage here is mu Internal to the NI 435x 2 5V 20 x 25 nA WW lex 20 25V d lexo Ground Referencing Off Ground Referencing On O CH2 Ground Referencing Off Ground Referencing Off Figure 2 7 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 0 5 NI 435x User Manual 2 18 ni com Chapter 2 Operating the NI 435x Device Ground referenced CH9 current source A 0 20 mA 0 40 mA Rsnunt User Supplied CH9 Floating current source CH8 0 20mA Rehunt User Supplied 0 40 mA o CH8 Voltage here is PEE 2 5V Rresistance Rra x1 mA O CH7 RTD f CH7 Voltage here is 2 5V Rresistance x 1 M O CH6 Resistance CH6 Voltage here is 2 5 V ad O lexi Note lex is present on the NI 4351 only Ground Referencing Off Open Thermocouple Detection Off Ground Referencing On F Open Thermocouple Detection Off Ground Referencing Off Open Thermocouple Detection Off Ground Referencing Off Open Thermocouple Detection Off Figure 2 8 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 6
68. of data to from a computer system involving communications channels operator interface devices and or data acquisition and control interfaces Integrated circuit Voltage excitation signal Inches A computer signal indicating that the CPU should suspend its current task to service a designated activity International Temperature Scale 1 Kelvin 2 Kilo the prefix for 1 024 or 2 9 used with B in quantifying data or computer memory A unit for data transfer that means 1 000 or 10 bytes s 1 000 samples A graphical programming language Digital device that stores the digital data based on a control signal Light emitting diode 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 220 when used with to quantify data or computer memory National Instruments Corporation G 5 NI 435x User Manual Glossary MB Mbytes s Measurement amp Automation Explorer MAX N NI DAQ NIST NMR noise NPN NTC 0 operating system PCI peak to peak PLC NI 435x User Manual Megabytes of memory A unit for data transfer that means 22 or 1 048 576 bytes s A controlled centralized configuration environment that allows you to configure all of your National Instruments DAQ GPIB IMAQ IVI Motion VISA and VXI devices National Instruments driver software for DAQ hardware National
69. on of temperature Most thermistors have a negative temperature coefficient NTC A temperature sensor created by joining two dissimilar metals The junction produces a small voltage as a function of the temperature Transistor transistor logic One or more analog or digital output samples Typically the number of output samples in an update is equal to the number of channels in the output group The rate at which the measurement data is updated Universal Serial Bus The basic unit of electromotive force or electric pressure that causes electric current to flow One volt is defined as the electromotive force to make one ampere current flow through a one ohm resistor Virtual instrument 1 A combination of hardware and or software elements typically used with a PC that has the functionality of a classic standalone instrument 2 A LabVIEW software module VI which consists of a front panel user interface and a block diagram program Channel names that can be defined outside the application and used without having to perform scaling operations G 8 ni com Index Numerics 4 wire ohms measurement mode purpose and use 2 2 range selection 2 2 A AC noise effects minimizing DC voltage measurement 2 13 RTDs thermistors and resistors 2 27 thermocouples 2 10 accuracy specifications calculation examples A 6 DC voltage table A 4 RTD tables A 3 thermistor table A 4 amplifier characteristic
70. onclude that the thermocouple is open Notice that when open thermocouple detection is on and the floating thermocouple is not broken a very small amount of current is injected into the thermocouple The value of the current is approximately 125 nA when ground referencing also is on If the thermocouple is very long the injected current can cause an error voltage to develop in the lead resistance of the thermocouple that is indistinguishable from the thermocouple voltage you are measuring You can estimate this error voltage with the following formula error voltage resistance of thermocouple x 125 nA For example if you use a 100 ft long 24 AWG J type thermocouple with a resistance of 0 878 Q per double foot the error voltage generated is approximately 11 which corresponds to about 0 2 C If this error is too large for the measurement you can reduce the error by reducing the thermocouple resistance or by lowering the length of the thermocouple or gauge of the wire use a wire of larger diameter Alternatively you can switch off the open thermocouple detection to eliminate the current injected into the thermocouple AC Noise Effects The NI 435x rejects AC voltages as specified in normal mode rejection NMR in Appendix A Specifications However if the amplitudes of the AC voltages are large compared to the DC voltages or if the peak value AC plus DC of the measured voltage is outside the input range the NI 435x may exh
71. onversion devices Plug in products and devices such as the DAQPad 1200 which connects to your computer parallel port are all examples of DAQ devices SCXI modules are distinct from devices with the exception of the SCXI 1200 which is a hybrid Digital ground signal Digital input and output NI 435x User Manual Glossary drivers dynamic range E EEPROM EMF event F filters ft gain GND H hardware NI 435x User Manual Software that controls a specific hardware device such as a DAQ device or a GPIB interface The ratio of the largest signal level a circuit can handle to the smallest signal level it can handle usually taken to be the noise level normally expressed in decibels Electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed Electromotive force The condition or state of an analog or digital signal Digital or analog circuits that change the frequency characteristics of a signal Feet Factor by which a signal is amplified sometimes expressed in decibels Ground Physical components of a computer system such as the circuit boards plug in boards chassis enclosures peripherals cables and so on Hertz the number of scans read or updates written per second G 4 ni com I O IC Tex in interrupt ITS kbytes s kS L LabVIEW latch LED Glossary Input output the transfer
72. ormation about the information columns in the Virtual Channels view 3 TheActive Channel column displays all the virtual channels you have created in MAX for your device To enable logging for each channel place a checkmark in the Log Enabled checkbox to the right of each channel name Tip To add a virtual channel click Create channel and follow the instructions in the Create New Channel wizard Refer to the Creating Calculated Channels section for information about creating calculated channels for VI Logger tasks National Instruments Corporation 1 11 NI 435x User Manual Chapter 1 Introduction NI 435x User Manual Configuring Events for a Logging Task You can configure events to be logged in your task that will appear in the Events view Complete the following steps to configure the events for a logging task 1 In the NI DAQ Channels view right click the Channels column and select Events 2 Check and uncheck the desired events to select which events to display for the channels 3 You also can right click the table cells to access more options to modify these conditions Creating Calculated Channels You can set up mathematical equations that use virtual channels using math channels For example for channels Channel 0 and Channel 1 you could enter the equation Channel 0 Channel 1 to subtract one from the other The result would be a calculated channel Complete the following steps to create a calculated c
73. ouples and other transducers the NI 453x device uses the widest range for all channels which can make the thermocouple measurements appear noisier Optimizing Measurements NI 435x User Manual To make accurate thermocouple measurements set the onboard programmable ground referencing and open thermocouple detection appropriately Also consider problems associated with AC noise effects thermal EMF and other errors as discussed in the following sections 2 8 ni com Chapter 2 Operating the NI 435x Device Auto Zero Auto Zero removes any offset errors in the measurement Analog channel 1 CH1 on the TC 2190 TBX 68T and CB 68T is dedicated for Auto Zero CH1 is connected to CH1 on these accessories You can measure the voltage offset on this Auto Zero channel and subtract it from the voltage measurements on other channels Hence you can compensate for any residual offset error the NI 435x may have This compensation is especially useful when the NI 435x device is operating at an ambient temperature other than that of calibration 23 C typical iyi Note When measuring the transducer channel with Auto Zero and or cold junction compensation the NI 435x device operates at its multi channel rate Refer to Table 2 1 for this rate Programmable Ground Referencing If you determine that the thermocouple is ground referenced switch off ground referencing on that channel If you determine that the thermocouple is floating switch on
74. ples with grounded or exposed junctions connected to grounded test points NI 435x User Manual 2 4 ni com Chapter 2 Operating the NI 435x Device e The outputs of plug in devices with nonisolated outputs Voltage across RTDs thermistors or resistors that you may be measuring using the built in current sources of the NI 435x Using Programmable Ground Referencing The NI 435x devices have software programmable ground referencing on every channel which you can use to ground reference a floating signal source This connects to ground through a 10 MQ resistor and provides a ground reference for the floating signal source Even if the signal source is ground referenced this resistance minimizes the effects of ground loops as long as the source impedance and the lead wire resistance is less than 100 Q Thus you can take accurate measurements even if you are uncertain whether the signal source is floating or ground referenced Because you can set ground referencing on a channel by channel basis you can have ground referenced signal sources connected to some channels and floating signal sources connected to other channels in the same measurement setup Table 2 2 summarizes the settings to use for ground referencing Table 2 2 Using Programmable Ground Referencing Programmable Signal Source Ground Referencing Floating On Ground referenced Off Note Programmable ground referencing applies to voltage a
75. powered off or is in the low power suspend mode suspend mode 1 blink Attached state The NI USB 4350 is recognized but not configured 2 blinks Addressed state The host computer detects the NI USB 4350 but cannot configure it because the device driver is improperly installed or system resources are unavailable Check the software installation National Instruments Corporation 1 7 NI 435x User Manual Chapter 1 Introduction Table 1 1 LED State Patterns for the NI USB 4350 States Continued LED State Description 3 blinks Power supply failure The internal power supply shut down Refer to the Power Considerations section for more information 4 blinks General error state Contact NI Refer to Appendix C Technical Support and Professional Services for contact information The LED blinks in one second intervals during each cycle The LED then waits three seconds before repeating the cycle Safety For safety information that is relevant to the NI 435x devices refer to the Read Me First Safety and Radio Frequency Interference document in the NI 435x shipping kit or at ni com manuals Configuring the Hardware in MAX To configure the NI 435x hardware in MAX complete the following steps 1 10 NI 435x User Manual Double click the Measurement amp Automation icon on the desktop to open MAX Expand Devices and Interfaces Expand Traditional NI DAQ Legacy Devices
76. red Resistance Measurement Technique R lt 1kQ 4 wire 1kQO lt R lt 10kQ 4 wire or 3 wire R gt 10kQ 4 wire 3 wire or 2 wire NI 435x User Manual 2 26 ni com Chapter 2 Operating the NI 435x Device Self Heating The current source on the NI 435x is designed so that error resulting from self heating is negligible in most cases When current is passed through an RTD or a thermistor both are resistive devices the power dissipated is equal to R and heats the resistive devices This self heating is typically specified by manufacturers in the form of the dissipation constant The dissipation constant is the power required to heat the thermistor by 1 C from ambient temperature and it is usually represented in units of mW C The dissipation constant depends significantly on how easily heat is transferred away from the thermistor so the dissipation constant may be specified for different media in still air water or oil bath Thermistors with their small size and high resistance are particularly prone to these self heating errors 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 5 000 Q thermistor powered by a 25 UA excitation current dissipates as follows PR 25 pA x 5 000 Q 3 1 yW If this thermistor has a dissipation constant of 10 mW C the thermistor self heats by only 0 003 C Thus the small value of th
77. rements Verify that this load is within the allowed limits Refer to the Excitation section of Appendix A Specifications for the maximum load resistance For resistance higher than 25 a settling time of over 1 s may be required when changing channels to achieve the specified accuracy The NI 435x analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered on and 17 VDC when powered off UN Caution Never apply voltages above these levels to the inputs To prevent possible safety hazards the maximum voltage between any of the analog inputs and the computer ground should never exceed 42 VDC when the NI 435x is powered on and 17 VDC when the NI 435x is powered off National Instruments Corporation 2 17 NI 435x User Manual Chapter 2 Operating the NI 435x Device Voltage here is 2 5V 20 Rejthermistor lex OF Rita R thermistor x 25 LAT Thermistor O CH5 Ground Referencing Off F Open Thermocouple Ground Referenced Thermocouple Voltage here is 0 CH4 CH5 Detection Off Open Thermocouple 2 5V 20 Rejthermistor Rra x 25 LAT Floating Thermocouple 0 CH3 CH4 Detection On Open Thermocouple CH3 Detection On R Open Thermocouple Voltage here is o CH2 Detection Off o CH1 Ground Referencing On 2 5V 20 kQ Auto Zero Open Therm
78. s A 7 analog input specifications amplifier characteristics A 7 dynamic characteristics A 8 excitation A 8 input characteristics A 7 auto zero optimization DC voltage measurement 2 12 RTDs thermistors and resistors 2 25 thermocouples 2 9 bus interface specifications A 9 calibration certificate NI resources C 2 Callendar Van Dusen coefficients table 2 22 cold junction effect of figure 2 7 National Instruments Corporation CompactPCI using with PXI 1 2 conventions used in the manual ix current source 2 14 D DC voltage accuracy table A 4 DC voltage measurement connecting DC voltage signal 2 11 input ranges 2 11 optimizing measurements AC noise effects 2 13 auto zero method 2 12 programmable gound referencing 2 12 programmable open thermocouple detection 2 12 source impedance 2 13 thermal EMF 2 13 Declaration of Conformity NI resources C 1 diagnostic tools NI resources C 1 digital I O and alarm output specifications 9 digital inputs and outputs connecting 2 29 DIO application examples figure 2 29 inadequate number of input lines note 2 30 logic family thresholds table 2 30 preventing safety hazards caution 2 29 documentation conventions used in manual ix NI resources C 1 related documentation x drivers NI resources C 1 dynamic characteristics A 8 NI 435x User Manual Index E equipment optional 1 13 examples x examples NI resourc
79. surement Mode nene ene 2 1 ceni re deine eon ood deed ees 2 2 Choosmg a Reading Rate eot e pi tette ehe esee etd 2 2 Knowing the Signal Source esses eene rennen rem ener 2 4 Floating Signal SOUfCe eerte ete E D iit ete 2 4 Ground Referenced Signal Source sse 2 4 Using Programmable Ground Referencing eeeeseeeeeeeene ee 2 5 Using Programmable Open Thermocouple Detection esee 2 5 Measuring Temperature with 1 2 6 Connecting the Thermocouple esee enne 2 8 Input Ran SOS oerte mt t me teeth 2 8 Optimizing Measurements eseesseseseeseeeneeeen eee een eene enne 2 8 Cui ZETO p 2 9 Programmable Ground Referencing eee 2 9 Programmable Open Thermocouple Detection 2 10 AC Noise Effects ue abe ie Ms rer 2 10 Therma Re OR ete RO tee HERR 2 11 Measuring DC Voltage ood eeu eee od ge 2 11 Connecting the DC Voltage Signal eee 2 11 Input inte E hene ees 2 11 Optimizing Meas reiments cp iere tb rene ama mee nent 2 12 VANDIE EA T 2 12 Programmable Ground Referencing ese 2 12 Programmable Open Thermocouple Detection 2 12 Source Impedance ER S ORE 2 13 AG Noise Bffects
80. t case common mode voltage for the given range Specifications improve if actual common mode voltage is less than worst case Measurement accuracy is affected by source impedance National Instruments Corporation A 5 NI 435x User Manual Appendix Specifications Accuracy Calculation Examples The following are accuracy calculation examples NI 435x User Manual Measurement of 760 C using J type thermocouple at 28 C ambient temperature filter setting of 10 Hz accuracy is 0 42 C Measurement of 760 C using J type thermocouple with NI 4350 at 38 C and accessory cold junction sensor at 23 C filter setting of 10 Hz accuracy is 0 48 C as a result of 0 42 C 38 C to 35 C x 0 02 Measurement of 760 C using J type thermocouple with NI 4350 and accessory cold junction sensor at 38 C filter setting of 10 Hz accuracy is 0 73 C as a result of 0 42 38 to 35 x 0 02 0 25 C Measurement of V using 1 25 V range filter setting of 60 Hz at 28 C ambient temperature after 90 days of calibration with Auto Zero at 0 V common mode voltage accuracy is 119 as a result of 1 V x 0 0101 18 uV Measurement of V using 1 25 V range filter setting of 60 Hz at 38 C ambient temperature after 90 days of calibration with Auto Zero at 0 5 V common mode voltage accuracy is 139 as a result of 1 V x 0 0101 18 uV 38 C to 35 C x 1 V x 0 0004 C
81. te RS 2 13 Thermal EMF ener b eene tentem 2 13 Measuring Resistance and Measuring Temperature with RTDs and Thermistors 2 13 Using the Current S OUrce ys diee t P RED EORR 2 14 Connecting Resistors ba euet eee den ti rede 2 14 Input Ranges eiie arredo tere Deep 2 16 Introduction to RIDS abo ete e ent 2 20 Relationship of Resistance and Temperature in RTDs 2 20 Connecting the RID stata eG et aa ee ted 2 22 Introduction to Thermistors eese nennen nne eene 2 23 Resistance Temperature Characteristic of Thermistors 2 24 Connecting the Thermistor eese 2 25 NI 435x User Manual vi ni com Optimizing Measurements esse Auto soiien in tides Programmable Ground Referencing Programmable Open Thermocouple Detection Connecting to External Circuits 2 Wire 3 Wire and 4 Wire Measurements Self Heating AC Noise Effects eicere Thermal ecce ette Using Digital Inputs and Outputs eee Connecting the Digital Input and Output Appendix A Specifications Appendix B Signal Connections Appendix C Technical Support and Professional Services Glossary Index National Instruments Corporation vii Contents NI 435x User Manual About This Manual Conventions This manual describes the National Instruments
82. tection allows you to detect a broken thermocouple You can measure resistance up to 600 using the built in 25 LA precision current source on all NI 435x hardware and up to 15 with the additional built in 1 mA precision current source on the NI PXI PCI 4351 Also programmable TTL compatible digital I O DIO lines monitor TTL level inputs interface with external devices and generate alarms A system based upon NI 435x hardware offers flexibility performance and compact size making it ideal for service repair and manufacturing and for use in industrial and laboratory environments Detailed specifications for the NI 435x devices are in Appendix A Specifications National Instruments Corporation 1 1 NI 435x User Manual Chapter 1 Introduction Using PXI with CompactPCl Configuration Using PXI compatible products with standard CompactPCI products is an important feature provided by the PXI Specification Refer to www pxisa org for more information The NI PXI 4351 does not have connections to reserved lines on the CompactPCI J2 connector Therefore you can use the NI PXI 4351 in a CompactPCI system that uses J2 connector lines for purposes other than PXI The NI 435x is a completely software configurable plug and play instrument The plug and play services query the instrument and allocate the required resources and the operating system then enables the instrument for operation Software Options for
83. temperature 2 20 optimizing measurements 2 25 relationship of resistance and temperature 2 20 resistance temperature curve figure 2 21 S self heating errors due to 2 27 signal connections using the NI 435x ISA USB PXI PCI with the TBX 68 table B 1 signal sources floating signal source 2 4 ground referenced signal source 2 4 software NI resources C 1 source impedance DC voltage measurement 2 13 specifications accuracy calculation examples A 6 DC voltage table A 4 RTD tables A 3 thermistor table 4 analog input amplifier characteristics A 7 dynamic characterics A 8 excitation A 8 input characteristics A 7 ni com bus interface 9 digital I O and alarm outputs A 9 physical A 10 power requirements A 9 T technical support C 1 temperature measurement RTDs connecting 2 14 optimizing measurements 2 25 relationship of resistance and temperature 2 20 thermistors connecting 2 25 optimizing measurements 2 25 resistance temperature characteristics 2 24 thermocouples cold junction effect figure 2 7 connecting 2 8 input ranges 2 8 optimizing measurements 2 8 thermal EMF minimizing DC voltage measurement 2 13 RTDs thermistors and resistors 2 28 thermocouples 2 11 thermistors accuracy specifications table A 4 advantages and disadvantages 2 23 connecting 2 25 optimizing measurements 2 25 resistance temperature characteristics 2 24 resistance temper
84. the NI 435x You can use LabVIEW LabWindows CVI Microsoft Visual Basic C C or VI Logger to program and use the NI 435x This section provides details on the software choices available for the NI 435x What Is the NI 435x Instrument Driver NI 435x User Manual An instrument driver packages instrument capabilities as a set of standard functions Each function corresponds to a programmatic operation such as configuring reading from writing to and starting and stopping measurements An instrument driver reduces the program development time and simplifies instrument control by eliminating the need to learn complex programming protocol for each instrument The NI 435x instrument driver provides programmability in a standard instrument driver format The instrument driver application programming interface API was designed after a traditional full featured data logger instrument driver The NI 435x instrument driver is VXI plug and play compatible and also contains the source code so you can examine and modify it The NI 435x instrument driver works with LabVIEW LabWindows CVI or conventional programming languages such as C C and Visual Basic Refer to the NI 435x LabVIEW Reference Help and the NI 435x C C CVI VB Help at Start Programs National Instruments NI 435x Documentation 1 2 ni com Chapter 1 Introduction What Is LabVIEW LabVIEW is a powerful graphical programming language for building instrumentation
85. tional Instruments Corporation 1 13 NI 435x User Manual Operating the NI 435x Device This chapter describes how to use the NI 435x device and includes operation tips on taking measurements with temperature sensors such as thermocouples RTDs and thermistors as well as measuring voltages and resistances UN Caution Refer to the Read Me First Safety and Radio Frequency Interference document before removing equipment covers or connecting disconnecting any signal wires Warming up the NI 435x Device To minimize the effects of thermal drift and to ensure the specified accuracy allow the NI 435x device to warm up for at least 10 minutes after startup before taking measurements To maximize the relative accuracy of measurements take all measurements after the NI 435x device warms up for 30 minutes Choosing a Measurement Mode You can configure the analog input channels for measuring outputs of various transducers as follows e Voltage e Thermocouples e Resistors e RTDs 3 Note When you are using Traditional NI DAQ Legacy virtual channels in VI Logger the measurement mode is chosen by the specified sensor type National Instruments Corporation 2 1 NI 435x User Manual Chapter 2 Operating the NI 435x Device Available Ranges The volts mode has six bipolar input ranges 625 mV 1 25 V 2 5 V 3 75 V x 7 5 V and 15 V The resistance mode has six corresponding input ranges when used with the built in 2
86. to physically connect the relevant pieces of the system Consult these guides when you are making connections NI 435x User Manual Complete the following steps to refer to the NI 435x examples through the NI Example Finder in LabVIEW 1 Launch LabVIEW 2 Select Open 3 Select Examples 4 Enter a keyword to search all available examples X ni com Introduction This chapter describes the NI 435x high precision temperature and voltage meters and describes the optional software and equipment About the NI 435x High Precision DAQ Devices The NI 435x devices for PXI PCI and USB feature accurate thermocouple and DC voltage meters You also can take temperature measurements with resistance temperature detectors RTDs or thermistors resistance measurements using built in precision current sources and current measurements using external shunt resistors The NI 435x hardware is plug and play compatible fully software calibrated and compatible with a variety of operating systems NI 435x hardware has a 24 bit sigma delta analog to digital converter ADC with differential analog inputs The low leakage construction and analog and digital filtering provide excellent resolution accuracy and noise rejection Software programmable ground referencing enables you to reference a floating signal without compromising voltage measurements even if the floating signal is ground referenced Software programmable open thermocouple de
87. to the inputs UN Caution To prevent possible safety hazards the maximum voltage between any of the analog inputs and the computer ground should never exceed 42 VDC when the NI 435x is powered on and 17 VDC when the NI 435x is powered off Input Ranges The NI 435x has six bipolar input ranges available for measuring DC voltage These ranges are 625 mV 1 25 V 2 5 V 3 75 V 7 5 V and 15 V The NI 435x can measure DC voltage to the specified accuracy as long as the voltage is within the selected input range To get the best resolution noise rejection and accuracy choose the smallest possible range Make sure that each signal input to CH and CH is within the common mode limits of this input range The input common mode limits are 22 5 V and 15 V for the lower three and higher three input ranges respectively 3 Note If scanning voltages in different ranges the NI 435x uses the widest voltage range for all channels which can make the lower voltage signal measurements appear noisier National Instruments Corporation 2 11 NI 435x User Manual Chapter 2 Operating the NI 435x Device Optimizing Measurements To make accurate voltage measurements program the onboard ground referencing and open thermocouple detection appropriately Also consider problems associated with AC noise effects thermal EMFs and other errors as discussed in the following sections Auto Zero Auto Zero removes any offset errors in the meas
88. urement Analog channel 1 CH1 on the TBX 68T TC 2190 and CB 68T is dedicated for Auto Zero CH1 is connected to CH1 on these accessories When using a TBX 68 accessory connect CH to CH any channel to make that channel useful for Auto Zero You can measure the voltage offset on this Auto Zero channel and subtract it from the voltage measurements on other channels This way you can compensate for any residual offset error the NI 435x may have This compensation is especially useful when the NI 435x is operating at an ambient temperature other than that of calibration 23 typical Note When measuring the transducer channel with Auto Zero the NI 435x operates at its multi channel rate Refer to Table 2 1 for this rate Programmable Ground Referencing If you determine that the signal source is ground referenced switch off ground referencing on that channel If you determine that the signal source is floating switch on ground referencing on that channel Otherwise the inputs may float out of the input common mode limits of the NI 435x When you use the TBX 68T and CB 68T accessories always switch on ground referencing on CH1 Doing this ground references the Auto Zero channel Note When using VI Logger in MAX with Traditional NI DAQ Legacy virtual channels with the accessories including the CB 68T TC 2190 or TBX 68T the ground referencing switch on the Auto Zero channel is automatically set appropriately
89. used 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 thermistors upper ranges are typically limited to around 300 C Figure 2 10 shows the resistance temperature curve for a 5 000 Q thermistor The curve of a platinum 100 Q RTD also is shown for comparison National Instruments Corporation 2 23 NI 435x User Manual Chapter 2 Operating the NI 435x Device Resistance Q Thermistor 5 000 Q at 25 C RTD PT 100 Q at 0 50 100 150 Temperature C 200 250 NI 435x User Manual Figure 2 10 Resistance Temperature Curve of a Thermistor The thermistor has been used primarily for high resolution measurements over limited temperature ranges Continuous improvements in thermistor stability accuracy and availability of interchangeable thermistors have prompted increased usage of thermistors in all types of industries Resistance Temperature Characteristic of Thermistors The resistance temperature behavior of thermistors is highly dependent upon the manufacturing process Therefore thermistor manufacturers have not standardized thermistor curves to the extent that thermocouple or RTD curves are standardized Typically thermistor manufacturers supply the resistance versus temperature
90. ustrial or American standard 0 003911 or the International Temperature Scale ITS 90 which is used with wire wound RTDs 0 003925 Table 2 4 lists the Callendar Van Dusen coefficients for each of these three platinum RTD curves National Instruments Corporation 2 21 NI 435x User Manual Chapter 2 Operating the NI 435x Device Table 2 4 Callendar Van Dusen Coefficients Corresponding to Common RTDs Temperature Standard Coefficient A B 751 0 00385055 3 9083 1073 5 715 x 107 4 183 x 107 DIN 43760 0 003850 3 9080 x 10 5 8019 x 1077 4 2735 x 10712 American 0 003911 3 9692 x 10 5 8495 x 10 7 4 2325 x 10 12 ITS 90 0 003925 3 9848 x 10 5 870 x 10 7 4 0000 x 10 2 For temperatures below 0 only C 0 0 for temperatures above 0 B Note NI software packages such as NI 435x MAX Create New Channel Wizard LabVIEW and LabWindows CVI include routines that perform these conversions for different types of RTDs based on the various commonly used standards Connecting the RTD You can use signal connection techniques described in the Connecting Resistors section for any RTD The preferred RTD measurement method is to use a 4 wire connection as shown in Figure 2 4 to minimize errors due to lead resistance For example if you connect an RTD in a 2 wire configuration as shown in Figure 2 3 a lead resistance of 0 3 Q in each wire results in
91. voltage V cold junction Computed in step 2 4 Convert the resulting voltage to temperature using a standard thermocouple conversion formula 5 Usethe CJC setting of Manual on the configured thermocouple channel Connecting the Thermocouple The NI 435x accessories the TC 2190 TBX 68T and CB 68T for the NI 435x for PXI PCI and USB are designed to be used with thermocouples Consult the accessory installation guide for instructions on how to connect the thermocouples To make accurate measurements make sure that the common mode voltage of the thermocouple is within the common mode limits of the selected input range UN Caution To prevent possible safety hazards the maximum voltage between any of the analog inputs and the computer ground should never exceed 42 VDC when the NI 435x is powered on and 17 VDC when the NI 435x is powered off Input Ranges The NI 435x analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered on and 17 VDC when the NI 435x device is powered off Never apply voltages above these levels to the inputs Choose the 625 mV range in volts mode when you are measuring thermocouples You can measure both the thermocouples and the thermistor cold junction sensor on the NI 435x accessory in the same scan by choosing the 25 range for measuring the thermistor These ranges offer the best resolution noise rejection and accuracy Note Ifscanning thermoc

NI 435x User Manual - National Instruments

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