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NI 4350/4351 User Manual - Artisan Technology Group

1. 3 11 Optimizing Measurements 3 12 Auto Zero 3 12 Programmable Ground Referencing 3 12 Programmable Open Thermocouple Detection 3 13 Source Impedance 3 13 AC Noise Effects 3 13 Thermal EMF 3 13 Measuring Temperature with RTDs and Thermistors and Measuring Resistance 3 14 Introduction to RTDs 3 14 Relationship of Resistance and Temperature in RTDs 3 15 Connecting Your RTD 3 16 Introduction to Thermistors 3 19 Resistance Temperature Characteristic of Thermistors 3 20 Connecting Your Thermistor 3 21 Connecting Your Resistor
2. 3 21 Input Ranges 3 23 Optimizing Measurements 3 24 Auto Zero 3 24 Programmable Ground Referencing 3 25 Programmable Open Thermocouple Detection 3 25 Connecting to External Circuits 3 25 Two Wire Three Wire and Four Wire Measurements 3 25 Self Heating 3 26 AC Noise Effects 3 27 Thermal EMF 3 27 Contents National Instruments Corporation vii NI 4350 4351 User Manual Using the Current Source 3 28 Using Digital Inputs and Outputs 3 28 Connecting Your Digital Input and Output 3 29 Appendix A Specifications Appendix B
3. 1 5 Optional Equipment 1 6 Chapter 2 Installation and Configuration Software Installation 2 1 Hardware Installation 2 1 Configuration 2 7 Power Considerations for the NI 4350 USB 2 7 Chapter 3 NI 435x Operation Warming up Your NI 435x Instrument 3 1 Choosing a Measurement Mode 3 1 Choosing a Range 3 2 Choosing a Reading Rate 3 2 Contents NI 4350 4351 User Manual vi National Instruments Corporation Knowing Your Signal Source 3 4 Floating Signal Source
4. 3 23 Figure 3 12 Examples of DIO Applications 3 29 Contents NI 4350 4351 User Manual viii National Instruments Corporation Tables Table 2 1 LED Patterns for the NI 4350 USB States 2 4 Table 3 1 Filtering and Sample Rates 3 3 Table 3 2 Using Programmable Ground Referencing 3 5 Table 3 3 Using Programmable Open Thermocouple Detection 3 6 Table 3 4 Callendar Van Dusen Coefficients Corresponding to Common RTDs 3 16 Table 3 5 Guidelines for Resistance Measurement 3 26 Table 3 6 Logic Family Thresholds 3 30 Table B 1 Using the NI 4350 PCMCIA with the CB 27 B 1 Table B 2 Using the NI 435x ISA USB PXI PCI with the TBX 68 B 3 National Instruments Corporation ix NI 4350 4351 User Manual About This Manual This manual describes the electrical and mechanical aspects of the NI 4350 4351 family of instruments and contains information concerning its operation and programming Orga
5. Chapter 3 NI 435x Operation National Instruments Corporation 3 17 NI 4350 4351 User Manual add errors to your readings For example consider a two wire RTD element connected to the NI 435x instrument accessory that also supplies a constant current source IEX to excite the RTD As shown in Figure 3 4 the voltage drop across the lead resistance RL adds to the measured voltage Figure 3 4 Two Wire RTD Measurement For example a lead resistance RL of 0 3 in each wire adds a 0 6 error to the resistance measurement For a platinum RTD with 0 00385 the resistance equals a 0 6 0 385 C 1 6 C error If you are using lead lengths greater than 10 ft you may need to compensate for this lead resistance in order to increase accuracy The preferred RTD measurement method is to use a four wire RTD One pair of wires carries the current through the RTD the other pair senses the voltage across the RTD Because only negligible current flows through the sensing wires the lead resistance error of RL2 and RL3 is negligible Figure 3 5 illustrates this configuration Figure 3 5 Four Wire RTD Measurement IEX IEX0 or IEX1 RTD RL RL CH CH IEX IEX0 or IEX1 IEX IEX0 or IEX1 RTD RL2 RL1 RL3 RL4 CH CH IEX IEX0 or IEX1 Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 18 National Instruments C
6. 3 4 Ground Referenced Signal Source 3 4 Using Programmable Ground Referencing 3 4 Using Programmable Open Thermocouple Detection 3 5 Measuring Temperature with Thermocouples 3 6 Connecting Your Thermocouple 3 8 Input Ranges 3 8 Optimizing Measurements 3 8 Auto Zero 3 9 Programmable Ground Referencing 3 9 Programmable Open Thermocouple Detection 3 10 AC Noise Effects 3 10 Thermal EMF 3 11 Measuring DC Voltage 3 11 Connecting Your DC Voltage Signal 3 11 Input Ranges
7. 10 M between CH and ground software selectable Input bias current lt 500 pA CMR DC 50 Hz 60 Hz 400 Hz Range 2 5 V 80 dB Range lt 2 5 V 100 dB NMR 50 Hz 60 Hz 400 Hz gt 100 dB Dynamic Characteristics Bandwidth 20 Hz Step response full scale step Accuracy Time s 0 1 0 3 0 01 0 5 0 0015 2 4 0 001 3 0 0004 7 Appendix A Specifications National Instruments Corporation A 9 NI 4350 4351 User Manual Excitation Number of channels 2 Digital I O and Alarm Outputs Number of lines PCMCIA 4 ISA USB PXI PCI 8 Compatibility TTL DIO lt 0 3 7 gt Power on state Tristate weak pull up Data transfers Programmed I O Bus Interface Type Slave Plug and Play Parameter IEX or IEX0 IEX1 Level 25 A 1 mA Maximum Load Resistance 600 k 15 k Temperature Coefficient 15 ppm C 15 ppm C Level Minimum Maximum Input low voltage 0 0 V 0 8 V Input high voltage 2 0 V 5 0 V Vcc Input low curren
8. Touch the antistatic package to a metal part on your computer chassis before removing the instrument from the package Remove the instrument from the package and inspect the instrument for loose components or any other sign of damage Notify National Instruments if the instrument appears damaged in any way Do not install a damaged instrument in your computer Chapter 1 Introduction NI 4350 4351 User Manual 1 4 National Instruments Corporation Never touch the exposed pins of the connector Also do not touch the printed circuit board or any components on board This may affect performance of the instrument Caution The NI 435x ISA PXI PCI is ESD contamination sensitive Handle the board using the edges or metal bracket NI 4350 USB Your NI 4350 USB is shipped in an antistatic vinyl package when you are not using your NI 4350 USB store in it this package Because your NI 4350 USB is enclosed in a fully shielded case no additional electrostatic precautions are necessary However for your own safety and to protect your NI 4350 USB never attempt to touch the pins of the connectors Software Programming Choices There are several options to choose from to program and use your National Instruments DAQ instruments You can use LabVIEW LabWindows CVI VirtualBench or the NI435X instrument driver National Instruments Application Software LabVIEW and LabWindows CVI are innovative
9. Fax on Demand Support Fax on Demand is a 24 hour information retrieval system containing a library of documents on a wide range of technical information You can access Fax on Demand from a touch tone telephone at 512 418 1111 E Mail Support Currently USA Only You can submit technical support questions to the applications engineering team through e mail at the Internet address listed below Remember to include your name address and phone number so we can contact you with solutions and suggestions support natinst com Telephone and Fax Support National Instruments has branch offices all over the world Use the list below to find the technical support number for your country If there is no National Instruments office in your country contact the source from which you purchased your software to obtain support Country Telephone Fax Australia 03 9879 5166 03 9879 6277 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Brazil 011 288 3336 011 288 8528 Canada Ontario 905 785 0085 905 785 0086 Canada Qu bec 514 694 8521 514 694 4399 Denmark 45 76 26 00 45 76 26 02 Finland 09 725 725 11 09 725 725 55 France 01 48 14 24 24 01 48 14 24 14 Germany 089 741 31 30 089 714 60 35 Hong Kong 2645 3186 2686 8505 Israel 03 6120092 03 6120095 Italy 02 413091 02 41309215 Japan 03 5472 2970 03 5472 2977 Korea 02 596 7456 02 596 7455 Mexico 5 520 2635 5 520 3282 Netherlands 0348 433466 034
10. 7 5 k and 15 k with the built in 1 mA current source on the NI 4351 PXI PCI Choose the smallest range for the best measurement results Note With VirtualBench the NI435X instrument driver or the Measurement amp Automation Explorer channel wizard you can specify the range based on your sensor type in engineering units appropriate to the sensor This sensor range is used to automatically set the actual hardware range Choosing a Reading Rate The reading rate is the rate at which your NI 435x takes a new measurement This rate has a direct relationship with the digital filter built into the ADC used in the NI 435x The digital filter has the characteristics shown in Figure 3 1 You can set the frequency of the first notch of this filter to 10 50 or 60 Hz Setting the notch filter at one of these frequencies rejects any noise at that frequency as well as at all its multiples Figure 3 1 Digital Filter Characteristics for 10 Hz Setting 0 20 40 60 80 100 120 Gain dB Frequency Hz 0 10 20 30 40 50 60 Chapter 3 NI 435x Operation National Instruments Corporation 3 3 NI 4350 4351 User Manual 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 To determine th
11. 90 Day 1 Year 10 Hz 50 Hz 60 Hz 10 Hz 50 Hz 60 Hz Reading C V 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 71 106 125 160 185 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 Appendix A Specifications National Instruments Corporation A 5 NI 4350 4351 User Manual Resistance Accuracy with IEX or IEX0 6 Resistance Accuracy with IEX1 7 6 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 k may require 1 s setting time Range of Reading 15 35 C Add with Auto zero 15 35 C Add without Auto zero 15 35 C Temperature Coefficient 0 15 C 35 55 C Filter Setting Filter Setting 24 Hr 90 Day 1 Year 10 Hz 50 Hz 60 Hz 10 Hz 50 Hz 60 Hz Reading C 600000 0 0435 0 0464 0 0494 20 11 23 64 24 63 24 17 26 67 27 37 0 0013 300000 0 0441 0 0470 0 0500 19 82 21 80 23 22 23 97 25 37 26 37 0 0013 150000 0 0453 0 0482 0 0512 19 54 20 16 20 67 23 77 24 21 24 57 0 0013
12. PXI and PCI The NI 435x instruments feature accurate thermocouple and DC voltage measurements You can also take temperature measurements with resistance temperature detectors RTDs thermistors ohm measurements using the built in precision current sources and current measurements using external shunt resistors You can use the NI 435x instrument with a personal computer to make the same measurements you would with standard bench top instruments such as data loggers and DMMs The NI 435x instruments contain a 24 bit sigma delta analog to digital converter ADC with differential analog inputs The low leakage construction along with analog and digital filtering provides excellent resolution accuracy and noise rejection With software programmable ground referencing you can reference your floating signal without compromising voltage measurements even if the floating signal is in fact ground referenced With software programmable open thermocouple detection you can quickly detect a thermocouple that may have broken before or during measurement You can measure up to a total resistance of 600 k using the built in 25 A precision current source on the NI 4350 PCMCIA ISA USB and NI 4351 PXI PCI and up to 15 k with the additional built in 1 mA precision current source on the NI 4351 PXI PCI In addition the NI 435x instruments have programmable TTL compatible digital Chapter 1 Introduction NI 4350 4351 User Manual
13. Signal Connections Appendix C Customer Communication Glossary Index Figures Figure 1 1 The Relationship between the Programming Environment NI435X Instrument Drivers NI DAQ and Your Hardware 1 6 Figure 3 1 Digital Filter Characteristics for 10 Hz Setting 3 2 Figure 3 2 Effect of the Cold Junction 3 7 Figure 3 3 Resistance Temperature Curve for a 100 Platinum RTD 3 15 Figure 3 4 Two Wire RTD Measurement 3 17 Figure 3 5 Four Wire RTD Measurement 3 17 Figure 3 6 Three Wire RTD Measurement 3 18 Figure 3 7 Three Wire RTD Measurement and Lead Wire Resistance Compensation 3 18 Figure 3 8 Resistance Temperature Curve of a Thermistor 3 20 Figure 3 9 Thermistor Measurement 3 21 Figure 3 10 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 0 5 3 22 Figure 3 11 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 6 9
14. 1 2 National Instruments Corporation I O DIO for monitoring TTL level inputs interfacing with external devices and generating alarms The NI 435x instrument is Plug and Play compatible The instrument is fully software calibrated Because the NI 435x instrument works with a variety of operating systems you can develop applications that scale across several platforms A system based on an NI 435x instrument offers flexibility performance and size making it ideal for service repair and manufacturing and for use in industrial and laboratory environments The NI 435x instrument used with your computer is a versatile cost effective platform for high resolution measurements Detailed specifications for the NI 435x instruments are in Appendix A Specifications Using PXI with CompactPCI Using PXI compatible products with standard CompactPCI products is an important feature provided by the PXI Specification Revision 1 0 If you use a PXI compatible plug in instrument in a standard CompactPCI chassis you will be unable to use PXI specific functions but you can still use the basic plug in instrument functions For example the RTSI bus on certain PXI instruments are available in a PXI chassis but not in a CompactPCI chassis However the NI 4351 PXI does not offer any PXI specific functions and therefore all of its functions are available on the CompactPCI bus What You Need to Get Started To set up and use your NI 435x
15. 100000 0 0355 0 0384 0 0414 0 51 1 00 1 28 1 26 1 60 1 80 0 0013 50000 0 0361 0 0390 0 0420 0 45 0 80 1 02 1 21 1 46 1 62 0 0013 25000 0 0373 0 0402 0 0432 0 41 0 54 0 74 1 18 1 28 1 42 0 0013 7 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 Range of Reading 15 35 C Add with Auto zero 15 35 C Add without Auto zero 15 35 C Temperature Coefficient 0 15 C 35 55 C Filter Setting Filter Setting 24 Hr 90 Day 1 Year 10 Hz 50 Hz 60 Hz 10 Hz 50 Hz 60 Hz Reading C 15000 0 0320 0 0349 0 0379 1 53 1 62 1 64 1 63 1 69 1 71 0 0013 7500 0 0326 0 0355 0 0385 1 52 1 57 1 61 1 63 1 66 1 69 0 0013 3750 0 0338 0 0367 0 0397 1 51 1 53 1 54 1 62 1 63 1 64 0 0013 2500 0 0240 0 0269 0 0299 0 03 0 04 0 05 0 05 0 06 0 06 0 0013 1250 0 0246 0 0275 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 0 02 0 02 0 04 0 04 0 04 0 0013 Appendix A Specifications NI 4350 4351 User Manual A 6 National Instruments Corporation Accuracy Calculation Examples The following are accuracy calculation examples Measurement of 760 C using J type thermocouple at 28 C ambient temperature filter setting of 10
16. 3 12 programmable open thermocouple detection 3 13 source impedance 3 13 thermal EMF 3 13 digital inputs and outputs 3 28 to 3 30 connecting 3 29 to 3 30 DIO application examples figure 3 29 inadequate number of input lines note 3 30 logic family thresholds table 3 30 preventing safety hazards caution 3 30 Index NI 4350 4351 User Manual I 2 National Instruments Corporation digital I O and alarm output specifications A 9 documentation conventions used in manual x National Instruments documentation xi organization of manual ix dynamic characteristics A 8 E electronic support services C 1 to C 2 e mail support C 2 environment specifications A 10 equipment optional 1 6 excitation specifications A 9 external circuits connecting to 3 25 F fax and telephone support numbers C 2 Fax on Demand support C 1 floating signal source 3 4 FTP support C 1 G ground referenced signal source 3 4 ground referencing programmable optimizing measurements DC voltage measurement 3 12 RTDs thermistors and resistors 3 25 thermocouples 3 9 to 3 10 purpose and use 3 4 to 3 5 settings table 3 5 H hardware installation 2 1 to 2 7 I input ranges DC voltage measurement 3 11 resistance measurement 3 23 to 3 24 thermocouples 3 8 installation hardware 2 1 to 2 7 NI 4350 ISA 2 2 to 2 3 NI 4350 PCMCIA 2 1 to 2 2 NI 4350 USB 2 3 to 2 4 NI 4351 PCI 2 6 to 2 7 NI 4351 P
17. 43760 standard 0 00385 the U S Industrial or American standard 0 003911 or the International Temperature Scale ITS 90 that is used with wire wound RTDs 0 003925 Table 3 4 lists the Callendar Van Dusen coefficients for each of these three platinum RTD curves Note Software packages such as VirtualBench NI435X instrument driver Measurement amp Automation Explorer 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 Your RTD Because the RTD is a resistive device you must pass current through the device and measure the resulting voltage However any resistance in the lead wires that connect your measurement system to the RTD will Table 3 4 Callendar Van Dusen Coefficients Corresponding to Common RTDs Standard Temperature Coefficient A B C IEC751 0 00385055 3 9083 10 3 5 775 10 7 4 183 10 1 DIN 43 760 0 003850 3 9080 10 3 5 8019 10 7 4 2735 10 12 American 0 003911 3 9692 10 3 5 8495 10 7 4 2325 10 12 ITS 90 0 003925 3 9848 10 3 5 870 10 7 4 0000 10 12 For temperatures below 0 C only C 0 0 for temperatures above 0 C TRTD 2 RRTD R0 1 A A2 4B RRTD R0 1
18. Corporation A 7 NI 4350 4351 User Manual ADC resolution 24 bits no missing codes Calibration cycle One year Reading rates Input coupling DC Maximum working voltage signal common mode Range gt 2 5 V Each input should remain within 15 V of ground Range 2 5 V Each input should remain within 2 5 V of ground Over voltage protection CH lt 0 8 15 gt IEX IEX0 IEX1 42 V powered on 17 V powered off Data transfers Interrupts programmed I O Warm up time 30 minutes Mode Reading Rate readings s Power Line Noise Rejection Single channel 10 10 50 50 60 60 Multiple channel acquisition 2 8 1 4 10 8 8 2 1 50 9 7 2 1 60 Resistance ranges 50 k Appendix A Specifications NI 4350 4351 User Manual A 8 National Instruments Corporation Amplifier Characteristics Input impedance Normal powered on gt 1 G in parallel with 0 39 F Powered off 10 k Overload 10 k Open thermocouple detection 10 M between CH and 2 5 V software selectable Ground referencing
19. Hz accuracy is 0 42 C directly from table 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 35 C 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 C 38 C 35 C 0 02 0 25 C Measurement of 1 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 V as a result of 1 V 0 0101 18 V Measurement of 1 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 V as a result of 1 V 0 0101 18 V 38 C 35 C 1 V 0 0004 C 1 V C 0 5V 10100 20 Analog Input Input Characteristics Number of channels PCMCIA 8 differential or 6 thermocouple ISA USB PXI PCI 16 differential or 14 thermocouple Digits 5 1 2 Type of ADC Sigma delta Appendix A Specifications National Instruments
20. PCI until its card edge connector is resting on the expansion slot receptacle Using slow evenly distributed pressure press the NI 4351 PCI straight down until it seats in the expansion slot 7 Reinstall the bracket retaining screw to secure the NI 4351 PCI to the back panel rail 8 Check the installation 9 Replace the computer cover and turn on the computer Chapter 2 Installation and Configuration National Instruments Corporation 2 7 NI 4350 4351 User Manual 10 Run Measurement amp Automation Explorer to make sure that your NI 4351 PCI is configured 11 Configure your accessory using Measurement amp Automation Explorer Your NI 4351 PCI is now installed Configuration Your NI 435x is a completely software configurable Plug and Play instrument The Plug and Play services query the instrument and allocate the required resources Then the operating system enables the instrument for operation Power Considerations for the NI 4350 USB The NI 4350 USB is designed to remain powered only when the USB cable connects it to the host PC and the PC is powered The NI 4350 USB is designed to run in a standalone mode drawing power only from the USB cable There are circumstances when the NI 4350 USB may require more power than the USB power supply can safely deliver so if the NI 4350 USB tries to draw more than the allowed current from the USB power supply internal protection circuitry w
21. PXI PCI Table B 2 Using the NI 435x ISA USB PXI PCI with the TBX 68 NI 435x ISA USB PXI PCI Signal Name TBX 68 Screw Terminal CH0 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 CH7 58 CH8 57 CH8 23 CH9 22 Appendix B Signal Connections NI 4350 4351 User Manual B 4 National Instruments Corporation CH9 55 CH10 54 CH10 21 CH11 19 CH11 53 CH12 52 CH12 18 CH13 17 CH13 50 CH14 49 CH14 15 CH15 13 CH15 46 IEX IEX0 NI 4351 12 IEX IEX0 NI 4351 45 IEX1 NI 4351 only 441 IEX1 NI 4351 only 101 DIO0 7 DIO1 6 DIO2 5 DIO3 4 Table B 2 Using the NI 435x ISA USB PXI PCI with the TBX 68 Continued NI 435x ISA USB PXI PCI Signal Name TBX 68 Screw Terminal Appendix B Signal Connections National Instruments Corporation B 5 NI 4350 4351 User Manual DIO4 37 DIO5 3 DIO6 2 DIO7 1 5V 82 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 1 Screw terminals 10 and 44 are AGND on the NI 4350 only and will not be labeled AGND on Revision C or higher of the TBX 68T 2 The current available may be limited to less than 50 mA typical when using the NI
22. Referencing On Open Thermocouple Detection On Ground Referencing Off Open Thermocouple Detection Off Ground Referencing On Open Thermocouple Detection Off Ground Referencing Off Open Thermocouple Detection Off Voltage here is 2 5 V 20 k Rcjthermistor Rrtd Rthermistor X 25 A Voltage here is 2 5 V 20 k Rcjthermistor X 25 A Voltage here is 2 5 V 20 k X 25 A Voltage here is 2 5 V 20 k Rcjthermistor Rrtd X 25 A Chapter 3 NI 435x Operation National Instruments Corporation 3 23 NI 4350 4351 User Manual Figure 3 11 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 6 9 The NI 435x instrument analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered up and 17 VDC when powered down Never apply voltages above these levels to the inputs 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 instrument is powered up and 17 VDC when the NI 435x instrument is powered down Input Ranges The NI 435x has six ranges for resistance measurements These ranges are 25 50 100 150 300 and 600 k with the 25 A current source These ranges correspond to the six input ranges available for measuring DC voltages developed across resistors These ra
23. _____MB Display adapter __________________________ Mouse ___yes ___no Other adapters installed _______________________________________ Hard disk capacity _____MB Brand _____________________________________________ Instruments used _________________________________________________________________ _______________________________________________________________________________ National Instruments hardware product model __________ Revision ______________________ Configuration ___________________________________________________________________ National Instruments software product ____________________________ Version ____________ Configuration ___________________________________________________________________ The problem is __________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ List any error messages ___________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ The following steps reproduce the problem ________________________________________
24. and TBX 68T is dedicated for auto zero CH1 is connected to CH1 on these accessories When using a CB 27 or TBX 68 accessory for RTDs 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 instrument may have This is especially useful when the NI 435x instrument is operating at an ambient temperature other than that of calibration 23 C typical Note When using the VirtualBench Logger along with NI 435x accessories PSH32 TC6 CB 27T TC 2190 or TBX 68T auto zeroing is implemented automatically Programmable Ground Referencing If you determine that your signal source is ground referenced switch off ground referencing on that channel If you determine that your 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 instrument When you use the CB 27T and TBX 68T accessories always switch on ground referencing on CH1 Doing this ground references the auto zero channel Note When using the VirtualBench Logger or NI435X Instrument Driver or the Measurement amp Automation Explorer channel wizard along with the NI 435x accessories PSH32 TC6 CB 27T TC 2190 or TBX 68T the ground referencing switch
25. or 220 when used with B to quantify data or computer memory MB megabytes of memory Mbytes s a unit for data transfer that means 220 or 1 048 576 bytes s N NI DAQ National Instruments driver software for DAQ hardware including computer based instruments NIST National Institute of Standards and Technology NMR normal mode rejection noise 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 NPN type of bipolar transistor NTC negative temperature coefficient O operating system base level software that controls a computer runs programs interacts with users and communicates with installed hardware or peripheral instruments Glossary National Instruments Corporation G 7 NI 4350 4351 User Manual P PC Card a credit card sized expansion card that fits in a PCMCIA slot PCI 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 PCMCIA an expansion bus architecture in notebook
26. resistances two 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 3 8 shows the resistance temperature curve for a 5 000 thermistor The curve of a 100 RTD is also shown for comparison Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 20 National Instruments Corporation Figure 3 8 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 the 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 have been standardized Typically thermistor manufacturers supply the resistance versus temperature curves or tables for their particular devices The thermistor curve however can be approximated relatively accurately with the Steinhart Hart equation Where T K is the temperature i
27. the accessory error in C only if the accessory TC 2190 PSH32 TC6 CB 27T TBX 68T is in the 0 to 15 C and 35 to 55 C temperature range Accuracy Specifications Thermocouple Accuracy1 1 Thermocouple measurement specifications include cold junction compensation error with sensor between 15 and 35 C isothermal accuracy and system 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 and 35 C Error C 15 35 C 1 Year 0 15 C 35 55 C Filter Setting Temperature Coefficient C C Accessory Error C Thermocouple Type C 10 Hz 50 Hz 60 Hz J 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 1000 0 60 0 69 0 81 1372 0 74 0 84 0 99 Appendix A Specifications NI 4350 4351 User Manual A 2 National Instruments Corporation N 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 1300 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 1000 0 46 0 50 0 57 T 150 0 81 0 96 1 1
28. voltage signal 3 11 input ranges 3 11 optimizing measurements 3 12 to 3 13 digital inputs and outputs 3 28 to 3 30 measurement mode selection 3 1 programmable ground referencing 3 4 to 3 5 programmable open thermocouple detection 3 5 to 3 6 range selection 3 2 reading rate selection 3 2 to 3 3 resistance measurement 3 21 to 3 23 input ranges 3 23 to 3 24 optimizing measurements 3 24 to 3 27 RTDs for measuring temperature 3 14 to 3 19 connecting 3 16 to 3 19 optimizing measurements 3 24 to 3 27 relationship of resistance and temperature 3 15 to 3 16 signal sources floating signal source 3 4 ground referenced signal source 3 4 thermistors for measuring temperature 3 19 to 3 21 connecting thermistors 3 21 optimizing measurements 3 24 to 3 27 resistance temperature characteristics 3 20 to 3 21 thermocouples for measuring temperature 3 6 to 3 11 connecting thermocouple 3 8 input ranges 3 8 optimizing measurements 3 8 to 3 11 warming up NI 435x instrument 3 1 optimizing measurements DC voltage 3 12 to 3 13 AC noise effects 3 13 auto zero method 3 12 programmable ground referencing 3 12 Index NI 4350 4351 User Manual I 4 National Instruments Corporation programmable open thermocouple detection 3 13 source impedance 3 13 thermal EMF 3 13 RTDs thermistors and resistors 3 24 to 3 27 AC noise effects 3 27 auto zero method 3 24 to 3 25 connecting to external circuits 3 25 guidel
29. 3 NI 435x Operation NI 4350 4351 User Manual 3 4 National Instruments Corporation Knowing Your Signal Source For accurate measurements you must determine whether your 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 and is therefore already connected to a common ground point with respect to the NI 435x instrument assuming that the computer is plugged into the same power system Examples of ground referenced signal sources are thermocouples with grounded or exposed junctions connected to grounded test points and the outputs of plug in devices with nonisolated outputs voltage across RTDs thermistors or resistors you may be measuring using the built in current sources of the NI 435x Using Programmable Ground Referencing Your NI 435x instrument has software programmable ground referencing on every channel which you can use to ground reference a floating signal source This connects CH to ground through a 10 M resistor and provides a ground re
30. 351 User Manual Caution The NI 4350 ISA is ESD contamination sensitive Handle the board using the metal bracket or edges 5 Insert the NI 4350 ISA in a 16 bit or 8 bit ISA slot Although it may fit tightly do not force the instrument into place 6 Screw the mounting bracket of the NI 4350 ISA to the back panel rail of the computer 7 Replace the cover 8 Plug in and turn on your computer 9 Run Measurement amp Automation Explorer to make sure that your NI 4350 ISA is configured 10 Configure your accessory using Measurement amp Automation Explorer Your NI 4350 ISA is now installed NI 4350 USB You can connect your NI 4350 USB to any available USB connector which supports high power bus powered peripheral devices The following are general installation instructions but consult your PC user manual or technical reference manual for specific instructions and warnings 1 Connect the USB cable from the computer port or from any other hub to the port on the NI 4350 USB 2 Your computer should detect the NI 4350 USB immediately When the computer recognizes the NI 4350 USB the LED on the front panel blinks or lights up depending on the status of your device If the LED comes on after the NI 4350 USB is connected to the host it is functioning properly If the LED remains off or blinks refer to Table 2 1 The LED blinks on and off for one second each for as many times as
31. 4350 USB Table B 2 Using the NI 435x ISA USB PXI PCI with the TBX 68 Continued NI 435x ISA USB PXI PCI Signal Name TBX 68 Screw Terminal National Instruments Corporation C 1 NI 4350 4351 User Manual AppendixC Customer Communication For your convenience this appendix contains forms to help you gather the information necessary to help us solve your technical problems and a form you can use to comment on the product documentation When you contact us we need the information on the Technical Support Form and the configuration form if your manual contains one about your system configuration to answer your questions as quickly as possible National Instruments has technical assistance through electronic fax and telephone systems to quickly provide the information you need Our electronic services include a web site an FTP site a fax on demand system and e mail support If you have a hardware or software problem first try the electronic support systems If the information available on these systems does not answer your questions we offer fax and telephone support through our technical support centers which are staffed by applications engineers Electronic Services FTP Support To access our FTP site log on to our Internet host ftp natinst com as anonymous and use your Internet address such as joesmith anywhere com as your password The support files and documents are located in the support directories
32. 7 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 1000 0 72 0 99 1 37 1767 0 91 1 19 1 60 S 250 0 91 1 28 1 83 0 07 0 13 1000 0 77 1 05 1 47 1767 0 96 1 27 1 72 B 600 1 08 1 64 2 47 0 11 0 00 1000 0 76 1 14 1 69 1820 0 74 1 05 1 50 Add when thermocouple accessory and NI 435x is outside 15 35 C temperature range Add when thermocouple accessory is outside 15 35 C temperature range Error C 15 35 C 1 Year 0 15 C 35 55 C Filter Setting Temperature Coefficient C C Accessory Error C Thermocouple Type C 10 Hz 50 Hz 60 Hz Appendix A Specifications National Instruments Corporation A 3 NI 4350 4351 User Manual RTD Accuracy with IEX or IEX0 2 RTD Accuracy with IEX1 3 2 RTD specifications assume that the 25 k 25 A 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 Error C 15 35 C 1 Year 0 15 C 35 55 C Filter Setting Temperature Coefficient C C RTD C 10 Hz 50 Hz 60 Hz Pt 100 200 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 3 RTD specifications assume that the 625 range 1 mA current sour
33. 8 430673 Norway 32 84 84 00 32 84 86 00 Singapore 2265886 2265887 Spain 91 640 0085 91 640 0533 Sweden 08 730 49 70 08 730 43 70 Switzerland 056 200 51 51 056 200 51 55 Taiwan 02 377 1200 02 737 4644 United Kingdom 01635 523545 01635 523154 United States 512 795 8248 512 794 5678 Technical Support Form Photocopy this form and update it each time you make changes to your software or hardware and use the completed copy of this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently If you are using any National Instruments hardware or software products related to this problem include the configuration forms from their user manuals Include additional pages if necessary Name __________________________________________________________________________ Company _______________________________________________________________________ Address ________________________________________________________________________ _______________________________________________________________________________ Fax ___ ___________________ Phone ___ _________________________________________ Computer brand ________________ Model ________________ Processor___________________ Operating system include version number ____________________________________________ Clock speed ______MHz RAM
34. Computer make and model _________________________________________________________ Microprocessor ___________________________________________________________________ Clock frequency or speed ___________________________________________________________ Type of video board installed ________________________________________________________ Operating system version ___________________________________________________________ Operating system mode ____________________________________________________________ Programming language ____________________________________________________________ Programming language version ______________________________________________________ Other boards in system _____________________________________________________________ Base I O address of other boards _____________________________________________________ DMA channels of other boards ______________________________________________________ Interrupt level of other boards _______________________________________________________ Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products This information helps us provide quality products to meet your needs Title NI 4350 4351 User Manual Edition Date December 1998 Part Number 321566C 01 Please comment on the completeness clarity and organization of the manual ________________________________________________________________________
35. 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 instrument accessory Avoid using dissimilar metal wires in connections Also minimize temperature gradients in the space enclosing the signal source the NI 435x instrument and its accessories Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 14 National Instruments Corporation Measuring Temperature with RTDs and Thermistors and Measuring Resistance 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 With the NI 435x you can excite your resistor with the built in precision current source and measure the resulting voltage When using LabVIEW set the measurements mode to 4 wire ohms When using the NI435X instrument driver set the measurement mode to Resistance These modes will return the measurements in units of resistance ohms by dividing the measured voltage with the calibrated value of the precision current source stored onbo
36. FIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of 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 reco
37. NI 4350 4351 User Manual High Precision Temperature and Voltage Meters NI 4350 4351 User Manual December 1998 Edition Part Number 321566C 01 Copyright 1997 1998 National Instruments Corporation All rights reserved Internet Support E mail support natinst com FTP Site ftp natinst com Web Address www natinst com Fax on Demand Support 512 418 1111 Telephone Support USA Tel 512 795 8248 Fax 512 794 5678 International Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 288 3336 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 5 520 2635 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Switzerland 056 200 51 51 Taiwan 02 377 1200 United Kingdom 01635 523545 National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin Texas 78730 5039 USA Tel 512 794 0100 Important Information Warranty The NI 4350 and NI 4351 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 warra
38. NI 435x instrument are protected against damage from voltages within 0 5 and 5 5 V with respect to digital ground DGND You should never apply voltages above these levels to these signals 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 Note If the number of digital input lines is not adequate for your application you can use the analog input channels to measure the voltage of the digital signal you want to measure Then you can determine the logic level based on the thresholds of the logic family of the digital signal you are monitoring Table 3 6 shows the thresholds of CMOS and TTL logic families using analog inputs as digital inputs Table 3 6 Logic Family Thresholds Logic Family Low High CMOS lt 0 8 V gt 2 0 V TTL lt 0 8 V gt 2 0 V Note Check your logic family data sheets for any variations National Instruments Corporation A 1 NI 4350 4351 User Manual AppendixA Specifications This appendix lists the specifications of the NI 4350 and NI 4351 These specifications are for 15 to 35 C ambient temperature range for one year unless otherwise specified All specifications are relative to calibration standards and require a 30 minute warm up period Specifications do not include transducer error Temperature coefficient is applicable for 0 to 15 C and 35 to 55 C For thermocouples add
39. PCI chassis Note The NI 4351 PXI does not have any connections to reserved lines on the CompactPCI J2 connector Therefore you can use the NI 4351 PXI in a CompactPCI system that uses J2 connector lines for purposes other than PXI 1 Turn off and unplug your PXI or CompactPCI chassis Warning To protect both yourself and the computer from electrical hazards the computer should remain off until you finish installing the NI 4351 PXI 2 Choose an unused PXI or CompactPCI 5 V peripheral slot 3 Remove the filler panel for the peripheral slot you have chosen 4 Touch a metal part on your chassis to discharge any static electricity that might be on your clothes or body Caution The NI 4351 PXI is ESD contamination sensitive Handle the board using the metal bracket or edges 5 Insert the NI 4351 PXI in the selected 5 V slot Use the injector ejector handle to fully inject the device into place 6 Screw the front panel of the NI 4351 PXI to the front panel mounting rails of the PXI or CompactPCI chassis 7 Visually verify the installation 8 Plug in and turn on the PXI or CompactPCI chassis 9 Run Measurement amp Automation Explorer to make sure that your NI 4351 PXI is configured 10 Configure your accessory using Measurement amp Automation Explorer Your NI 4351 PXI is now installed Chapter 2 Installation and Configuration NI 4350 4351 User Manual 2 6 National Instr
40. Remove the PCMCIA slot cover on your computer 4 Insert the 68 pin I O connector of the NI 4350 PCMCIA into the PCMCIA slot until the connector is firmly seated Notice that the NI 4350 PCMCIA connectors are keyed so that you can insert it in only one way 5 Run Measurement amp Automation Explorer to make sure that the NI 4350 PCMCIA is configured 6 Configure your accessory using Measurement amp Automation Explorer Your NI 4350 PCMCIA is now installed NI 4350 ISA You can install the NI 4350 ISA in any available ISA AT or XT slot in your computer However for best noise performance leave as much room as possible between the NI 4350 ISA and other hardware Before installing your NI 4350 ISA consult your computer user manual or technical reference manual for specific instructions and warnings Use the following general instructions to install your NI 4350 ISA 1 Write down your NI 4350 ISA serial number on the NI 4350 4351 Hardware and Software Configuration Form in Appendix C 2 Turn off and unplug your computer Warning To protect both yourself and the computer from electrical hazards the computer should remain off until you finish installing the NI 4350 ISA 3 Remove the top cover or access port to the I O channel 4 Remove the expansion slot cover on the back panel of the computer Chapter 2 Installation and Configuration National Instruments Corporation 2 3 NI 4350 4
41. XI 2 5 software 2 1 unpacking the NI 435x instruments 1 3 to 1 4 L LabVIEW and LabWindows CVI software 1 4 to 1 5 LEDs for NI 4350 USB after installation 2 3 patterns table 2 4 M manual See documentation measurement mode choosing 3 1 N National Instruments application software 1 4 to 1 5 NI 435x instruments See also operation of NI 435x instruments configuration 2 7 installation hardware 2 1 to 2 7 software 2 1 optional equipment 1 6 overview 1 1 to 1 2 Index National Instruments Corporation I 3 NI 4350 4351 User Manual power considerations for NI 4350 USB 2 7 to 2 8 requirements for getting started 1 2 to 1 3 software programming choices 1 4 to 1 6 National Instruments application software 1 4 to 1 5 NI435X instrument driver and NI DAQ 1 5 to 1 6 VirtualBench 1 5 unpacking 1 3 to 1 4 using PXI with CompactPCI 1 2 NI 4350 USB installation 2 3 to 2 4 LEDs after installation 2 3 patterns table 2 4 power considerations 2 7 to 2 8 NI435X instrument driver 1 5 to 1 6 NI DAQ driver software 1 5 to 1 6 noise effects AC See AC noise effects minimizing O open thermocouple detection programmable 3 5 to 3 6 optimizing measurements DC voltage measurement 3 13 RTDs thermistors and resistors 3 25 thermocouples 3 10 settings table 3 6 operation of NI 435x instruments 3 1 to 3 30 current source 3 28 DC voltage measurement 3 11 to 3 13 connecting DC
42. ____ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ NI 4350 4351 Hardware and Software Configuration Form Record the settings and revisions of your hardware and software on the line to the right of each item Complete a new copy of this form each time you revise your software or hardware configuration and use this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently National Instruments Products DAQ hardware ___________________________________________________________________ Programming choice _______________________________________________________________ National Instruments software _______________________________________________________ Other boards in system _____________________________________________________________ Base I O address of other boards _____________________________________________________ DMA channels of other boards ______________________________________________________ Interrupt level of other boards _______________________________________________________ Other Products
43. _______ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ If you find errors in the manual please record the page numbers and describe the errors _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ Thank you for your help Name _________________________________________________________________________ Title __________________________________________________________________________ Company _______________________________________________________________________ Address ________________________________
44. ________________________________________ _______________________________________________________________________________ Phone ___ __________________________ Fax ___ ___________________________________ Mail to Technical Publications Fax to Technical Publications National Instruments Corporation National Instruments Corporation 6504 Bridge Point Parkway 512 794 5678 Austin TX 78730 5039 National Instruments Corporation G 1 NI 4350 4351 User Manual Glossary Numbers Symbols percent positive of or plus negative of or minus plus or minus per degree ohm 5V 5 V output signal Prefix Meanings Value n nano 10 9 micro 10 6 m milli 10 3 k kilo 103 M mega 106 G giga 109 Glossary NI 4350 4351 User Manual G 2 National Instruments Corporation A A ampere unit of current AC alternating current AC coupled allowing the transmission of AC signals while blocking DC signals ADC analog to digital converter an electronic device often an integrated circuit that converts an analog voltage to a digital format AGND analog ground signal ANSI American National Standards Institute AT bus See bus attenuation decreasing the amplitude of a signal auto zeroing the process of removing an offset error from a measurement AWG American Wire Gauge B b bit one binary digit either 0 or 1 B byte ei
45. accessories the PSH32 TC6 and the CB 27T for the NI 4350 PCMCIA and the TC 2190 and the TBX 68T for the NI 435x ISA USB PXI PCI are designed to be used with thermocouples Consult your accessory installation guide for instructions on how to connect your thermocouples To make accurate measurements make sure that the common mode voltage of the thermocouple is within the input common mode limits of the selected input range The NI 435x instrument analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered up and 17 VDC when the NI 435x instrument is powered down You should never apply voltages above these levels to the inputs 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 instrument is powered up and 17 VDC when the NI 435x instrument is powered down Input Ranges 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 k range for measuring the thermistor These ranges offer the best resolution noise rejection and accuracy Optimizing Measurements To make accurate thermocouple measurements set the onboard programmable ground referencing and open thermocouple detection appropriately Also consider pr
46. alth and safety in medical or clinical treatment National Instruments Corporation v NI 4350 4351 User Manual Contents About This Manual Organization of This Manual ix Conventions Used in This Manual x National Instruments Documentation xi Customer Communication xi Chapter 1 Introduction About the NI 435x Instruments 1 1 Using PXI with CompactPCI 1 2 What You Need to Get Started 1 2 Unpacking 1 3 Software Programming Choices 1 4 National Instruments Application Software 1 4 VirtualBench 1 5 NI435X Instrument Driver and NI DAQ
47. an detect this voltage level in software and conclude that your thermocouple is open To understand how setting open thermocouple detection affects the accuracy of measurements refer to the programmable open thermocouple detection section later in this chapter You can set open thermocouple detection on a channel by channel basis Table 3 3 summarizes the settings you should use for open thermocouple detection Table 3 2 Using Programmable Ground Referencing Signal Source Programmable Ground Referencing Floating On Ground referenced Off Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 6 National Instruments Corporation Note The default setting for programmable open thermocouple detection in volts and 4 wire ohms measurement modes is off Measuring Temperature with Thermocouples The thermocouple is the most popular transducer for measuring temperature Because the thermocouple is inexpensive rugged and can operate over a very wide range of temperatures it is a versatile and useful sensor A thermocouple operates on the principle that the junction of two dissimilar metals generates a voltage that varies with temperature or thermal EMF However just measuring this voltage is not sufficient because connecting the thermocouple to the NI 435x instrument accessory creates the reference junction or cold junction shown in Figure 3 2 These additional junctions act as thermocouples themselves and produce th
48. ard The following sections explain the various measurement techniques in detail Introduction to RTDs 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 at 0 C RTDs are known for their excellent accuracy over a wide temperature range Some RTDs have accuracy as high as 0 01 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 C To accurately measure these small changes in resistance you may need to use special configurations that minimize errors from lead wire resistance Chapter 3 NI 435x Operation National Instruments Corporation 3 15 NI 4350 4351 User Manual 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 called alpha differs between RTD curves Although various manufacturers may specify differently is most commonly defined as the change in RTD resista
49. asurement amp Automation Explorer channel wizard your software includes examples that perform these temperature to voltage and voltage to temperature conversions for the cold junction thermistor and various types of thermocouples based on the National Institute of Standards and Technology NIST standard reference tables These examples are located in the DAQ analog input example library and have NI 435x in their title If you are not using either of the previous software options follow the steps below to perform cold junction compensation 1 Measure the resistance of the thermistor cold junction sensor Rthermistor cold junction and compute the cold junction temperature Tcold junction using the thermistor resistance temperature conversion formula 2 From this temperature of the cold junction Tcold junction compute the equivalent thermocouple voltage Vcold junction for this junction using a standard thermocouple conversion formula V2 Vthermocouple Vmeasured V1 Vmeasured Vthermocouple V1 V2 where V1 V2 Vcold junction Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 8 National Instruments Corporation 3 Measure the voltage Vmeasured and add the cold junction voltage Vcold junction computed in step 2 4 Convert the resulting voltage to temperature using a standard thermocouple conversion formula Connecting Your Thermocouple The NI 435x
50. ce 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 Error C 15 35 C 1 Year 0 15 C 35 55 C Filter Setting Temperature Coefficient C C RTD C 10 Hz 50 Hz 60 Hz Pt 100 200 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 Appendix A Specifications NI 4350 4351 User Manual A 4 National Instruments Corporation Thermistor Accuracy with IEX or IEX0 4 DC Voltage Accuracy5 4 Thermistor accuracy is valid for all filter settings Specifications assume that the 25 k range is used and worst case common mode voltage for this range is present Specifications improve is actual common mode voltage is less than worst case Accuracy C 15 35 C 1 Year Filter Setting 10 Hz 50 Hz 60 Hz Temperature Coefficient 0 15 C 35 55 C Thermistor C C C C 5 000 0 50 0 03 0 001 5 Voltage specifications do not include errors resulting from common mode voltages Calculate additional error because of common mode voltages as common mode voltage 10 CMR specification in db 20 Range of Reading 15 35 C Add V with Auto zero 15 35 C Add V without Auto zero 15 35 C Temperature Coefficient 0 15 C 35 55 C Filter Setting Filter Setting Volts C 24 Hr
51. e documentation or the NI DAQ documentation to help you write your application If you have a large complicated system it is worthwhile to look through the software documentation before you configure your hardware Accessory installation guides or manuals If you are using accessory products read the terminal block adapter and cable assembly installation guides They explain how to physically connect the relevant pieces of the system Consult these guides when you are making your connections Customer Communication National Instruments wants to receive your comments on our products and manuals We are interested in the applications you develop with our products and we want to help if you have problems with them To make it easy for you to contact us this manual contains comment and configuration forms for you to complete These forms are in Appendix C Customer Communication at the end of this manual National Instruments Corporation 1 1 NI 4350 4351 User Manual Chapter1 Introduction This chapter describes the NI 4350 4351 family of high precision temperature and voltage meters lists what you need to get started explains how to unpack your instrument and describes the optional software and optional equipment About the NI 435x Instruments Thank you for buying a National Instruments 435x instrument The NI 435x family consists of five instruments for the bus of your choice PCMCIA ISA Universal Serial Bus USB
52. e in the 4 wire ohms mode when you are measuring RTDs and thermistors for best results The NI 435x instrument 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 your signals will be accommodated Make sure that each signal input to CH and CH is within the input common mode limits of this input range The input common mode limits are 2 5 V and 15 V for the lower three and higher three input ranges respectively For resistance higher than 25 k a settling time of over 1 s may be required when changing channels to achieve the specified accuracy Optimizing Measurements In addition to the potential problems discussed in the sections on connecting your 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 is a method that instruments use to remove any offset errors in the measurement Analog channel 1 CH1 on the PSH32 TC6 CB 27T TC 2190 and TBX 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 This way you can compensate for any residual offset error the NI 435x i
53. e reading rate per channel when scanning multiple channels divide the multiple channel measurement reading rate in Table 3 1 by the number of channels in the scan In certain applications such as resistance measurements above 25 k or voltage measurements with more than 25 k of source resistance you should measure the same channel for up to 1 s then switch to another channel to achieve the specified accuracy 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 power line frequency PLF Table 3 1 shows which programming settings to use to reject harmonics of particular frequencies Table 3 1 Filtering and Sample Rates LabVIEW NI435X Instrument Driver VirtualBench Logger Equivalent Filter Setting Harmonics of Noise Frequencies Rejected Hz Single Channel Measurement Reading Rate readings s Multiple Channel Measurement Reading Rate readings s Notch Filter Frequency Setting Hz PLF Hz Reading Rate PLC PLF Hz 10 50 or 60 slow 5 6 40 50 60 400 10 50 60 and 400 10 2 8 1 4 50 50 fast 1 8 50 400 50 and 400 50 8 8 2 1 60 60 fast 1 60 60 60 9 7 2 1 Number of power line cycles used for filtering Power line frequency For resistance ranges of 50 k and higher Chapter
54. eir own voltages Thus the final measured voltage Vmeasured includes both the thermocouple voltage Vthermocouple and the cold junction voltage Vcold junction The method of compensating for these unwanted cold junction voltages is called cold junction compensation Table 3 3 Using Programmable Open Thermocouple Detection Signal Source Programmable Open Thermocouple Detection Thermocouples On or Off Voltage signal sources other than thermocouples Off RTDs thermistors and resistors connected to the built in current source Off Chapter 3 NI 435x Operation National Instruments Corporation 3 7 NI 4350 4351 User Manual Figure 3 2 Effect of the Cold Junction With the NI 435x instruments you can perform cold junction compensation in software To do this you can use the thermistor temperature sensor on the NI 435x accessory to measure the ambient temperature at the cold junction and compute the appropriate compensation for the unwanted thermoelectric voltages using software You have several options for performing cold junction compensation as shown below If you are using the NI435X instrument driver LabVIEW LabWindows CVI VirtualBench or the Measurement amp Automation Explorer channel wizard your software will automatically perform cold junction compensation on all channels configured as thermocouple channels If you are using LabVIEW and are not using the instrument driver or the Me
55. ents Corporation rms root mean square the square root of the average value of the square of the instantaneous signal amplitudes a measure of signal amplitude RSVDx reserved RTD resistance temperature detector A metallic probe that measures temperature based upon its resistance S s second a unit of time S sample S s samples per second used to express the rate at which a NI 435x samples an analog signal sigma delta technology used for analog to digital conversion sinter to cause to become a coherent mass by heating without melting system noise a measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded T TTL transistor transistor logic thermocouple kind of temperature sensor thermistor kind of temperature sensor U update 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 update rate the rate at which the measurement data is updated USB Universal Serial Bus Glossary National Instruments Corporation G 9 NI 4350 4351 User Manual V V volt an electric unit VI 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 progra
56. ermocouple detection is on and the floating thermocouple is not broken a very small amount of current is injected into the thermocouple It is approximately 125 nA when ground referencing is also on If the thermocouple is very long this 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 the thermocouple 125 nA For example if you use a 100 ft long 24 AWG J type thermocouple with a resistance of 0 878 per double foot the error voltage generated is approximately 11 V which corresponds to about 0 2 C If this error is too large for your measurement you can reduce the error by reducing the thermocouple resistance Do this by reducing the length of the thermocouple or lowering the AWG 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 Your NI 435x instrument rejects AC voltages as specified in 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 DC of the measured voltage is outside the input range the NI 435x instrument may exhibit additional errors To minimize these errors keep the thermoco
57. ference for your floating signal source Even if your 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 Thus you can take accurate measurements even if you are uncertain whether your 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 3 2 summarizes the settings to use for ground referencing Chapter 3 NI 435x Operation National Instruments Corporation 3 5 NI 4350 4351 User Manual Note The default setting for programmable ground referencing is on in volts measurement mode and off in 4 wire ohms mode Using Programmable Open Thermocouple Detection The NI 435x instruments have software programmable open thermocouple detection on every channel which you can use to detect an open or broken thermocouple This feature connects CH to 2 5 V through a 10 M resistor This resistor acts as a pull up resistor and consequently the voltage between CH and CH rises rapidly above 100 mV if your thermocouple breaks open All thermocouples functioning under normal conditions generate a voltage of less than 100 mV even at very high temperatures which makes this conclusion possible You c
58. fers only to the NI 4350 for computers that are USB compatible You may have software that refers to this instrument as the DAQPad 4350 NI 4350 4351 Refers to all instruments in the National Instruments 4350 and 4351 families NI 4351 PCI Refers only to the NI 4351 for PCI bus computers About This Manual National Instruments Corporation xi NI 4350 4351 User Manual NI 4351 PXI Refers only to the NI 4351 for PXI bus computers NI 435x Refers to all instruments in the National Instruments 4350 and 4351 families National Instruments Documentation The NI 4350 4351 User Manual is one piece of the documentation set for your computer based instrument system You could have any of several types of manuals depending on the hardware and software in your system Use the manuals you have as follows Your computer based instrument hardware documentation This documentation has detailed information about the DAQ hardware that plugs into or is connected to your computer Use this documentation for hardware installation and configuration instructions specification information about your DAQ hardware and application hints Software documentation You may have application software NI435X instrument driver software and NI DAQ software documentation National Instruments application software includes LabVIEW LabWindows CVI and VirtualBench After you set up your hardware system use either your application softwar
59. from sensors transducers and test probes or fixtures and inputting them to a computer for processing 2 collecting and measuring the same kinds of electrical signals with A D and or DIO boards plugged into a computer and possibly generating control signals with D A and or DIO boards in the same computer dB decibel the unit for expressing a logarithmic measure of the ratio of two signal levels dB 20 x log10 V1 V2 for signals in volts DC direct current DC coupled allowing the transmission of both AC and DC signals device a plug in data acquisition board card or instrument that can contain multiple channels and conversion devices Plug in boards PCMCIA cards and instruments such as the NI 4350 USB which connects to your computer USB port are all examples of DAQ devices Glossary NI 4350 4351 User Manual G 4 National Instruments Corporation DGND digital ground signal DIO digital input and output drivers software that controls a specific hardware instrument dynamic range 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 E EEPROM electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed EMF electromotive force event the condition or state of an analog or digital signal F filters digital or analog circuits tha
60. ght related bits of data an eight bit binary number Also used to denote the amount of memory required to store one byte of data bandwidth the range of frequencies present in a signal or the range of frequencies to which a measuring instrument can respond bipolar a signal range that includes both positive and negative values for example 5 V to 5 V buffer temporary storage for acquired data bus 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 Glossary National Instruments Corporation G 3 NI 4350 4351 User Manual C C Celsius channel pin or wire to which you apply or from which you read the analog or digital signal For digital signals you group channels to form ports Ports usually consist or either four or eight digital channels CHx channel signal clock hardware component that controls timing for reading from or writing to groups CMOS complimentary metal oxide semiconductor CMR common mode rejection CompactPCI refers to the core specification defined by the PCI Industrial Computer Manufacturer s Group PICMG coupling the manner in which a signal is connected from one location to another CPU central processing unit D DAQ data acquisition 1 collecting and measuring electrical signals
61. ground references the auto zero channel On all the NI 435x instrument accessories used with thermocouples analog channel CH0 is dedicated to the thermistor cold junction sensor The built in current source return terminal IEX or IEX0 is tied to 2 5 V through a resistor This references any resistor excited by the current source to ground Since this current source excites the cold junction thermistor CH0 is automatically ground referenced Therefore when measuring the voltage across this thermistor always switch off programmable ground referencing on CH0 Otherwise the leakage current flowing into the thermistor may cause erroneous measurements in all the channels that use the current source Current source terminal IEX1 is also tied to 2 5 V through a resistor Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 10 National Instruments Corporation Note When using VirtualBench Logger the Measurement amp Automation Explorer channel wizard or the NI435X Instrument Driver the ground referencing switch on the cold junction sensor channel and auto zero channel is set appropriately automatically 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 will rise rapidly above 100 mV at which point you can conclude that the thermocouple is open Notice that when open th
62. his Manual The following conventions are used in this manual The symbol indicates that the text following it applies only to a specific NI 435x instrument This icon to the left of bold italicized text denotes a note which alerts you to important information This icon to the left of bold italicized text denotes a caution which advises you of precautions to take to avoid injury data loss or a system crash This icon to the left of bold italicized text denotes a warning which advises you of precautions to take to avoid being electrically shocked bold Bold text denotes the names of menus menu items parameters dialog box dialog box buttons or options icons windows Windows 95 tabs or LEDs bold italic Bold italic text denotes a note caution or warning italic Italic text denotes emphasis a cross reference or an introduction to a key concept monospace Text in this font is used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions and for statements and comments taken from programs NI 4350 ISA Refers only to the NI 4350 for ISA bus computers You may have software that refers to this instrument as the PC 4350 NI 4350 PCMCIA Refers only to the NI 4350 for computers with a Type II PCMCIA slot You may have software that refers to this instrument as the DAQCard 4350 NI 4350 USB Re
63. hould never apply voltages above these levels to the inputs 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 instrument is powered up and 17 VDC when the NI 435x instrument is powered down Input Ranges Your NI 435x instrument 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 instrument 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 input common mode limits of this input range The input common mode limits are 2 5 V and 15 V for the lower three and higher three input ranges respectively Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 12 National Instruments Corporation 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 is a method that instruments use to remove offset errors in the measurement Analog channel 1 CH1 on the CB 27T
64. ill turn off most of the circuitry in the NI 4350 USB to protect the USB supply This over current condition makes the LED blink in the power supply overload pattern described in Table 2 1 Note When the NI 4350 USB turns off any data acquisition in progress will be aborted and the data will be lost The host computer has the ability to go into a power saving suspend mode and during this time the NI 4350 USB can go either into a low power mode also 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 Chapter 2 Installation and Configuration NI 4350 4351 User Manual 2 8 National Instruments Corporation In the powered static state of the NI 4350 USB all digital outputs will be static at a fixed voltage Note Refer to the NI DAQ function Set_DAQ_Device_Info in the NI DAQ documentation or to the Set DAQ Device Information vi in the LabVIEW documentation to change the settings that determine the behavior of the NI 4350 USB during the suspend state The default setting is to remain fully powered National Instruments Corporation 3 1 NI 4350 4351 User Manual Chapter3 NI 435x Operation This chapter describes how to use your NI 435x instrument and includes operation tips on taking measurements with temperature sensors such as thermocouples RTDs and thermistors as well as measuring voltages and resistances Warming up Y
65. 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 A 5 000 thermistor powered by a 25 A excitation current will dissipate I2R 25 A 2 5 000 3 1 W If this thermistor has a dissipation constant of 10 mW C the thermistor will self heat by only 0 003 C Thus the small value of the current source helps you prevent any appreciable error due to self heating RTDs are relatively immune to this problem of self heating because their resistance is relatively small 100 at 0 C for example Here 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 Table 3 5 Guidelines for Resistance Measurement Resistance Being Measured Measurement Technique R 1 k Four wire 1 k lt R 10 k Four wire or three wire R gt 10 k Four wire three wire or two wire Chapter 3 NI 435x Operation National Instruments Corporation 3 27 NI 4350 4351 User Manual higher in still air than in moving water The self heating in RTDs due to the built in 25 A is negligible When using 1 mA excitation current a 100 RTD would dissipate I2R 1 mA 2 100 0 1 mW If th
66. ines for resistance measurement table 3 26 programmable ground referencing 3 25 programmable open thermocouple detection 3 25 self heating 3 26 to 3 27 thermal EMF 3 27 two wire three wire and four wire measurements 3 25 to 3 26 thermocouples 3 8 to 3 11 AC noise effects 3 10 auto zero method 3 9 programmable ground referencing 3 9 to 3 10 programmable open thermocouple detection 3 10 thermal EMF 3 11 optional equipment 1 6 P physical specifications A 10 power considerations for NI 4350 USB 2 7 to 2 8 power requirements A 10 programmable ground referencing See ground referencing programmable programmable open thermocouple detection See open thermocouple detection programmable PXI using with CompactPCI 1 2 R range selection for measurement mode 3 2 reading rate selection 3 2 to 3 3 determining reading rate per channel note 3 3 digital filter characteristics figure 3 2 filtering and sample rates table 3 3 reference junction 3 6 requirements for getting started 1 2 to 1 3 resistance accuracy specifications table A 5 resistance measurement 3 21 to 3 23 connecting resistors 3 21 to 3 23 multiple transducer connections to analog channels figures 3 22 to 3 23 preventing safety hazards caution 3 23 input ranges 3 23 to 3 24 optimizing 3 24 to 3 27 AC noise effects 3 27 auto zero method 3 24 to 3 25 connecting to external circuits 3 25 guidelines for resistance mea
67. instrument you will need the following K One of the following NI 435x instruments NI 4350 PCMCIA NI 4350 ISA NI 4350 USB NI 4351 PXI NI 4351 PCI Chapter 1 Introduction National Instruments Corporation 1 3 NI 4350 4351 User Manual K NI DAQ 6 5 for PC compatibles or higher K NI435X instrument driver K One of the following software packages and documentation VirtualBench 2 1 1a or higher LabVIEW 4 0 or higher LabWindows CVI 4 0 or higher BridgeVIEW 1 0 or higher Third party compiler K Optional cables and accessories K Your computer Unpacking NI 4350 PCMCIA Your NI 4350 PCMCIA is shipped in an antistatic vinyl case when you are not using your NI 4350 PCMCIA store it in this case Because your NI 4350 PCMCIA is enclosed in a fully shielded case no additional electrostatic precautions are necessary However for your own safety and to protect your NI 4350 PCMCIA never attempt to touch the pins of the connectors NI 4350 ISA NI 4351 PXI PCI Your NI 4350 ISA or NI 4351 PXI PCI is shipped in an antistatic vinyl package to prevent electrostatic damage to your instrument Electrostatic discharge can damage several components on the instrument To avoid such damage in handling the instrument take the following precautions Ground yourself via a grounding strap or by holding a grounded object
68. is RTD has a dissipation constant of 5 mW C the RTD will self heat by 0 02 C AC Noise Effects The NI 435x instruments reject 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 DC of the measured signal is outside the input range the NI 435x instrument may exhibit additional errors To minimize these errors keep the signal source and the NI 435x instrument 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 will provide you with 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 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 instrument accessory Avoid using dissimilar metal wires in connections Also keep out temperature gradients in the space enclosing the signal source the NI 435x instrument and its accessories Chapter 3 NI 435x Operation NI 4350 4351 Use
69. m VirtualBench software suite of stand alone virtual instruments that combine DAQ products software and PCs National Instruments Corporation I 1 NI 4350 4351 User Manual Index Numbers 4 wire ohms measurement mode purpose and use 3 1 range selection 3 2 A AC noise effects minimizing DC voltage measurement 3 13 RTDs thermistors and resistors 3 27 thermocouples 3 10 accuracy specifications A 1 to A 6 calculation examples A 6 DC voltage table A 4 resistance table A 5 RTD table A 3 thermistor table A 4 thermocouple table A 1 to A 2 amplifier characteristics A 8 analog input specifications A 6 to A 9 amplifier characteristics A 8 dynamic characteristics A 8 excitation A 9 input characteristics A 6 to A 7 auto zero optimization DC voltage measurement 3 12 RTDs thermistors and resistors 3 24 to 3 25 thermocouples 3 9 B bus interface specifications A 9 C Callendar Van Dusen coefficients table 3 16 cold junction compensation methods 3 7 to 3 8 definition 3 6 effect of figure 3 7 CompactPCI using with PXI 1 2 configuration 2 7 conventions used in manual x current source 3 28 customer communication xi C 1 to C 2 D DC voltage accuracy table A 4 DC voltage measurement 3 11 to 3 13 connecting DC voltage signal 3 11 input ranges 3 11 optimizing measurements 3 12 to 3 13 AC noise effects 3 13 auto zero method 3 12 programmable ground referencing
70. n kelvin equal to T C 273 15 and Rt is the resistance of the thermistor The coefficients a b and c can be Thermistor 5 000 at 25 C RTD PT 100 at 0 C Resistance W Temperature C 10 M 1 M 100 k 10 k 1 k 100 10 200 150 100 50 0 50 100 150 200 250 300 350 400 T K 1 a b Rt ln c Rt ln3 Chapter 3 NI 435x Operation National Instruments Corporation 3 21 NI 4350 4351 User Manual provided by the thermistor manufacturer or calculated from the resistance versus temperature curve Software packages such as LabVIEW and LabWindows CVI include routines that perform these conversions for some types of thermistors You can also modify these conversion routines for your particular type of thermistor Connecting Your Thermistor Because the thermistor is a resistive device you must pass a current through the thermistor to produce a voltage that can be measured by the NI 435x instrument The high resistance and high sensitivity of the thermistor simplify the necessary measurement circuitry and signal conditioning Special three wire or four wire connections are not necessary As shown in Figure 3 9 the measured voltage Vt will be equal to Rt Iex Figure 3 9 Thermistor Measurement See Figure 3 10 for an example of how you can use different transd
71. nce from 0 to 100 C divided by the resistance at 0 C divided by 100 C C R100 R0 R0 100 C where R100 is the resistance of the RTD at 100 C and R0 is the resistance of the RTD at 0 C For example a 100 platinum RTD with 0 00385 will measure 138 5 at 100 C Figure 3 3 shows a typical resistance temperature curve for a 100 platinum RTD Figure 3 3 Resistance Temperature Curve for a 100 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 RRTD R0 1 A t B t2 C t 100 t3 RTD PT 100 Resistance Temperature C 1 k 100 10 200 150 100 50 0 50 100 150 200 250 300 350 400 Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 16 National Instruments Corporation where RRTD is the resistance of the RTD at temperature TRTD R0 is the resistance of the RTD in at 0 C A B and C are the Callendar Van Dusen coefficients shown in Table 3 4 and TRTD 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 Most platinum RTD curves follow one of three standardized curves the DIN
72. necessary then waits three seconds before repeating the cycle Chapter 2 Installation and Configuration NI 4350 4351 User Manual 2 4 National Instruments Corporation 3 Run Measurement amp Automation Explorer to make sure that your NI 4350 USB is configured 4 Configure your accessory using Measurement amp Automation Explorer Table 2 1 LED Patterns for the NI 4350 USB States LED NI 4350 USB State Description On Configured state Your NI 4350 USB is configured Off Off or in the low power suspend mode Your NI 4350 USB is turned off or in the low power suspend mode 1 blink Attached state Your NI 4350 USB is recognized but not configured 2 blinks Addressed state This pattern is displayed if the host computer detects your NI 4350 USB but cannot configure it because NI DAQ is not properly installed or there are no system resources available Check your software installation 3 blinks Power supply failure This pattern is displayed if the internal power supply shuts down Refer to the Power Considerations for the NI 4350 USB section for more information 4 blinks General error state If this pattern is displayed contact National Instruments Chapter 2 Installation and Configuration National Instruments Corporation 2 5 NI 4350 4351 User Manual NI 4351 PXI You can install your NI 4351 PXI in any available 5 V peripheral slot in your PXI or Compact
73. nges are 625 mV 1 25 V 2 5 V 3 75 V 7 5 V and 15 V The NI 4351 PXI PCI CH7 Resistance CH6 CH6 RTD IEX1 CH7 IEX1 Voltage here is 2 5 V Voltage here is 2 5 V Rresistance X 1 mA Voltage here is 2 5 V Rresistance Rrtd X 1 mA Ground Referencing Off Open Thermocouple Detection Off Ground Referencing Off Open Thermocouple Detection Off Rshunt User Supplied CH8 CH8 Ground Referencing On Open Thermocouple Detection Off Floating current source 0 20 mA 0 40 mA Rshunt User Supplied CH9 CH9 Ground Referencing Off Open Thermocouple Detection Off Ground referenced current source 0 20 mA 0 40 mA Note IEX1 is present on the NI 4351 only Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 24 National Instruments Corporation has six additional ranges of 625 1 25 k 2 5 k 3 75 k 7 5 k and 15 k with the 1 mA current source To determine the most suitable input range for your application estimate the voltage developed across the resistor by following the procedure outlined in Figures 3 10 and 3 11 Also estimate the common mode voltage at the inputs and verify that the range you select can handle that common mode voltage Also estimate the common mode voltage at the inputs and verify that the range you select can handle that common mode voltage Choose the lowest rang
74. nization of This Manual The NI 4350 4351 User Manual is organized as follows Chapter 1 Introduction describes the NI 4350 4351 family of high precision temperature and voltage meters lists what you need to get started explains how to unpack your instrument and describes the optional software and optional equipment Chapter 2 Installation and Configuration describes how to install and configure your NI 435x instrument Chapter 3 NI 435x Operation describes how to use your NI 435x instrument and includes operation tips on taking measurements with temperature sensors such as thermocouples RTDs and thermistors as well as measuring voltage and resistances Appendix A Specifications lists the specifications of the NI 4350 and NI 4351 Appendix B Signal Connections explains the signal correlation between your NI 435x and the accessories you might use with it Appendix C Customer Communication contains forms you can use to request help from National Instruments or to comment on our products The Glossary contains an alphabetical list and description of terms used in this manual including acronyms abbreviations definitions metric prefixes mnemonics and symbols The Index alphabetically lists topics covered in this manual including the page where you can find the topic About This Manual NI 4350 4351 User Manual x National Instruments Corporation Conventions Used in T
75. nstrument may have This is especially useful when your NI 435x instrument is operating at an ambient temperature other than that of calibration 23 C typical Use the Chapter 3 NI 435x Operation National Instruments Corporation 3 25 NI 4350 4351 User Manual four wire mode in LabVIEW while reading the offset for resistance measurements Note When using VirtualBench Logger along with NI 435x accessories PSH32 TC6 CB 27T TC 2190 or TBX 68T auto zeroing is implemented automatically Programmable Ground Referencing Always switch off ground referencing on the channel connected to a resistor excited by the current source The current source return terminals IEX IEX0 and IEX1 are tied to 2 5 V through internal circuits This causes any resistor excited by the current source to be ground referenced Otherwise the leakage current flowing into the resistor can cause erroneous measurement 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 measurement for all channels that use the current source Connecting to External Circuits See Figures 3 10 and 3 11 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
76. nty 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 manual is accurate The document has been carefully reviewed for technical accuracy In the event that technical 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 SPECI
77. oblems associated with AC noise effects thermal EMF and other errors as discussed in the following sections Chapter 3 NI 435x Operation National Instruments Corporation 3 9 NI 4350 4351 User Manual Auto Zero Auto zero is a method that instruments use to remove any offset errors in the measurement Analog channel 1 CH1 on the PSH32 TC6 CB 27T TC 2190 and TBX 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 This way you can compensate for any residual offset error the NI 435x instrument may have This is especially useful when your NI 435x instrument is operating at an ambient temperature other than that of calibration 23 C typical Note When using the VirtualBench Logger along with NI 435x accessories PSH32 TC6 CB 27T TC 2190 or TBX 68T auto zeroing is implemented automatically Programmable Ground Referencing If you determine that your thermocouple is ground referenced switch off ground referencing on that channel If you determine that your thermocouple is floating switch on ground referencing on that channel Otherwise the thermocouple inputs may float out of the input common mode limits of the NI 435x instrument When you use the PSH32 TC6 CB 27T TC 2190 and TBX 68T accessories always switch on ground referencing on CH1 Doing this
78. of thermistors 3 19 thermocouples for measuring temperature 3 6 to 3 11 accuracy specifications table A 1 to A 2 cold junction compensation options 3 7 to 3 8 cold junction effect figure 3 7 connecting thermocouple 3 8 input ranges 3 8 optimizing measurements 3 8 to 3 11 AC noise effects 3 10 auto zero method 3 9 programmable ground referencing 3 9 to 3 10 programmable open thermocouple detection 3 10 thermal EMF 3 11 overview 3 6 U unpacking NI 435x instruments 1 3 to 1 4 V VirtualBench software 1 5 volts measurement mode purpose and use 3 1 range selection 3 2 W warming up NI 435x instrument 3 1
79. on VirtualBench VirtualBench is a suite of VIs that allows you to use your data acquisition products just as you use stand alone instruments but you benefit from the processing display and storage capabilities of PCs VirtualBench instruments load and save waveform data to disk in the same format that can be used with popular spreadsheet programs and word processors A report generation capability complements the raw data storage by adding timestamps measurements user name and comments Your NI 435x works with VirtualBench Logger and VirtualBench DIO VirtualBench Logger is a turn key application that allows you to make measurements as you would with a standard bench type data logger VirtualBench DIO allows you to read from or write to the digital I O lines NI435X Instrument Driver and NI DAQ The NI435X instrument driver provides flexibility and programmability in a standard instrument driver format The instrument driver application programming interface API is designed after a classical full featured data logger instrument driver The NI435X instrument driver works with LabVIEW LabWindows CVI or conventional programming languages such as C C and Visual Basic Whether you are using the NI435X instrument driver VirtualBench Logger LabVIEW or LabWindows CVI your application uses the NI DAQ driver software as illustrated in Figure 1 1 Chapter 1 Introduction NI 4350 4351 User Manual 1 6 National Instrumen
80. on the auto zero channel is set appropriately automatically Chapter 3 NI 435x Operation National Instruments Corporation 3 13 NI 4350 4351 User Manual Programmable Open Thermocouple Detection When you measure voltage signals other than thermocouples always switch off the onboard open thermocouple detection Source Impedance For best results maintain the source impedance and the lead wire resistance of your signal at less than 100 If either of these is greater than 25 k you should measure the same channel for up to 1 s then switch to another channel to achieve the specified accuracy AC Noise Effects Your NI 435x instrument rejects AC voltages as specified in 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 DC of the measured voltage is outside the input range the NI 435x instrument may exhibit additional errors To minimize these errors keep the signal source and the NI 435x instrument 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 will provide you with 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
81. orporation Alternatively you can use a three wire RTD instead Figure 3 6 shows a the three wire RTD configuration with a current source In this configuration the resistance RL1 of only one lead adds error to the measurement Figure 3 6 Three Wire RTD Measurement Another variation of the three wire RTD configuration is shown in Figure 3 7 In this configuration the effects of the lead wire resistance cancel out as long as all three wires have the same lead resistance Figure 3 7 Three Wire RTD Measurement and Lead Wire Resistance Compensation See Figure 3 10 for an example of how you can use different transducers connected to analog channels in the same measurement setup IEX IEX0 or IEX1 RTD RL1 RL2 RL3 CH CH IEX IEX0 or IEX1 IEX IEX0 or IEX1 RTD RL1 RL2 RL3 CHn CHn IEX IEX0 or IEX1 CHn 1 CHn 1 RRTD RCHn RCH n 1 if RL1 RL2 RL3 Chapter 3 NI 435x Operation National Instruments Corporation 3 19 NI 4350 4351 User Manual Note For best results use the 1 mA current source when using the NI 4351 and the 25 A source when using the NI 4350 with RTDs with resistances below 1 k See the readme doc for software issues regarding the 1 mA source Introduction to Thermistors A thermistor is a piece of semiconductor made from metal oxides pressed into a small bead disk wafer or other shape sintered at high temperatu
82. otes and follow the instructions given there for your operating system and your software If you are using programming languages such as Visual Basic C or C with NI DAQ follow the NI DAQ instructions for installing third party compilers After you have installed your software you are ready to install your hardware Follow the appropriate instructions for your instrument Hardware Installation NI 4350 PCMCIA You can install your NI 4350 PCMCIA in any available Type II PCMCIA slot in your computer Windows 95 or higher includes the Plug and Play services your operating system will use Windows NT 4 0 or higher includes the drivers needed to use PCMCIA cards The operating system configures the NI 4350 PCMCIA and automatically assigns the base address and the interrupt level Before installing your NI 4350 PCMCIA consult your computer user manual or technical reference manual for specific instructions and warnings Chapter 2 Installation and Configuration NI 4350 4351 User Manual 2 2 National Instruments Corporation Use the following general instructions to install your NI 4350 PCMCIA 1 Write down your NI 4350 PCMCIA serial number on the NI 4350 4351 Hardware and Software Configuration Form in Appendix C 2 Turn off your computer If your computer and operating system support hot insertion you can insert or remove the NI 4350 PCMCIA at any time whether the computer is powered on or off 3
83. our NI 435x Instrument To minimize the effects of thermal drift and to ensure the specified accuracy allow the NI 435x instrument to warm up for at least 10 minutes after power up before taking measurements To maximize the relative accuracy of measurements take all measurements after your NI 435x instrument warms up for about 30 minutes Choosing a Measurement Mode Each analog input channel can be configured in two possible measurement modes the volts mode or the 4 wire ohms mode Use the volts mode for thermocouple and voltage measurements and the 4 wire ohms mode for RTD thermistor and resistance measurements using the built in current source to provide excitation for your resistive sensors In the 4 wire ohms mode the software will return the resistance value by dividing the voltage measured by the value of the current source stored onboard Note VirtualBench the NI435X instrument driver and the Measurement amp Automation Explorer channel wizard select the measurement mode automatically depending on the sensor type you specify Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 2 National Instruments Corporation Choosing a Range The volts mode has six bipolar input ranges 625 mV 1 25 V 2 5 V 3 75 V 7 5 V and 15 V The 4 wire ohms mode has six corresponding input ranges when used with the built in 25 current source 25 50 100 150 300 and 600 k and 625 1 2 k 3 75 k
84. program development software packages for data acquisition and control applications LabVIEW uses graphical programming whereas LabWindows CVI enhances traditional programming languages Both packages include extensive libraries for data acquisition instrument control data analysis and graphical data presentation LabVIEW features interactive graphics a state of the art user interface and a powerful graphical programming language The LabVIEW Data Acquisition VI Library a series of VIs for using LabVIEW with National Instruments DAQ hardware is included with LabVIEW The LabVIEW Data Acquisition VI Library is functionally equivalent to the NI DAQ software LabWindows CVI features interactive graphics a state of the art user interface and uses the ANSI standard C programming language The LabWindows CVI Data Acquisition Library a series of functions for using LabWindows CVI with National Instruments DAQ hardware is Chapter 1 Introduction National Instruments Corporation 1 5 NI 4350 4351 User Manual included with the NI DAQ software kit The LabWindows CVI Data Acquisition library is functionally equivalent to the NI DAQ software NI 435x instruments are supported by the Easy I O for DAQ library in LabWindows CVI Use of the NI435X instrument driver is recommended while using LabWindows CVI Using LabVIEW or LabWindows CVI software will greatly reduce the development time for your data acquisition and control applicati
85. r Manual 3 28 National Instruments Corporation Using the Current Source The NI 435x features a precision current source which supplies 25 A and provides excitation to a total maximum resistance of 600 k The NI 4351 has an additional precision current source which supplies 1 mA and provides excitation to a total maximum resistance of 15 k These resistances can be in the form of RTDs thermistors or any other resistor The calibrated value of the current source is stored on board Refer to the sections Measuring Temperature with RTDs and Thermistors and Measuring Resistance for details on how to use this current source Note See the readme doc file for software issues regarding the 1 mA current source Using Digital Inputs and Outputs The NI 435x features TTL compatible digital lines These lines can be individually configured either as inputs or as outputs At power up these digital lines are configured as high impedance inputs with a weak pull up You can use the DIO lines as an interface to control processes control events such as turning on and off heaters relays motors or lights generate patterns for testing and communicate with peripheral equipment If the current and voltage specifications of the DIO lines are not appropriate for your 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 t
86. rding storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks BridgeVIEW CVI DAQCard DAQMeter DAQPad LabVIEW NI DAQ PXI and VirtualBench are trademarks of National Instruments Corporation Product and company names mentioned herein are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure or by errors on the part of the user or application designer Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel and all traditional medical safeguards equipment and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used National Instruments products are NOT intended to be a substitute for any form of established process procedure or equipment used to monitor or safeguard human he
87. res 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 extremely high sensitivity For example a 2252 thermistor has a sensitivity of 100 C at room temperature Higher resistance thermistors can exhibit temperature coefficients of 10 k C or more In comparison a 100 platinum RTD has a sensitivity of only 0 4 C The small size of the thermistor bead also yields a very fast response to temperature changes Another advantage of the thermistor is its relatively high resistance Thermistors are available with base resistances at 25 C ranging from hundreds to millions of ohms This high resistance 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 four wire or three wire connections to reduce errors caused by lead wire
88. 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 is connected to external circuits that change the effective resistance of that resistor Two Wire Three Wire and Four Wire Measurements The discussion in Connecting Your RTD on whether to use two wire three wire or four wire earlier in this chapter applies to any resistance measurement Choose the appropriate measurement technique for your application as shown in Table 3 5 Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 26 National Instruments Corporation Self Heating The current source on the NI 435x instrument is designed such that any error resulting from self heating is negligible in most cases This section explains how that occurs When current is passed through an RTD or a thermistor both are resistive devices power dissipated is equal to I2R which heats the resistive devices This phenomena is called self heating and is typically specified by manufacturers in the form of the dissipation constant which is the power required to heat the thermistor by 1 C from ambient temperature and is usually has 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
89. rigger analog acquisitions To do this with the LabVIEW or NI435X instrument driver set up the analog acquisition configuration then poll the digital input line for your trigger condition and upon getting the trigger start the analog acquisition Chapter 3 NI 435x Operation National Instruments Corporation 3 29 NI 4350 4351 User Manual Connecting Your Digital Input and Output All NI 435x accessories are designed to be used for DIO Refer to your accessory installation guide for instructions on how to connect your DIO lines Figure 3 12 shows examples of how to connect DIO 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 ISA USB PXI PCI you can use the TBX 68T revision C or later 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 the ER Series Figure 3 12 Examples of DIO Applications 5 V DIO0 configured as an output DIO1 configured as an input DIO2 configured as an input DIO3 configured as an input DIO3 configured as an output DGND R4 R1 R2 R3 SW LED TTL or CMOS NPN Transistor Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 30 National Instruments Corporation The DIO lines of the
90. size computers It originated as a specification for add on memory cards written by the Personal Computer Memory Card International Association peak to peak a measure of signal amplitude the difference between the highest and lowest excursions of the signal PLC power line cycles PLF power line frequency Plug and Play devices that do not require dip switches or jumpers to configure devices resources on the instruments also called switchless instruments Plug and Play ISA a specification prepared by Microsoft Intel and other PC related companies that will result in PCs with plug in boards that can be fully configured in software without jumpers or switches on the boards port 1 a communications connection on a computer or remote controller 2 a digital port consisting of four or eight lines of digital input and or output PTC positive temperature coefficient PXI PCI eXtensions for Instrumentation an open specification that builds on the CompactPCI specification by adding instrumentation specific features R reading rate the rate in hertz at which each sample is updated resolution 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 16777216 resolution and 5 96 x 10 6 of full scale Glossary NI 4350 4351 User Manual G 8 National Instrum
91. specifications accuracy A 1 to A 6 calculation examples A 6 DC voltage table A 4 resistance table A 5 RTD table A 3 thermistor table A 4 thermocouple table A 1 to A 2 analog input A 5 to A 9 amplifier characteristics A 8 dynamic characteristics A 8 excitation A 9 input characteristics A 6 to A 7 bus interface A 9 digital I O and alarm outputs A 9 environment A 10 physical A 10 power requirements A 10 T technical support C 1 to C 2 telephone and fax support numbers C 2 temperature measurement RTDs 3 14 to 3 18 connecting 3 16 to 3 19 optimizing measurements 3 24 to 3 27 relationship of resistance and temperature 3 15 to 3 16 thermistors 3 19 to 3 21 connecting 3 21 optimizing measurements 3 24 to 3 27 resistance temperature characteristics 3 20 to 3 21 Index NI 4350 4351 User Manual I 6 National Instruments Corporation thermocouples 3 6 to 3 11 cold junction compensation options 3 7 to 3 8 cold junction effect figure 3 7 connecting thermocouple 3 8 input ranges 3 8 optimizing measurements 3 8 to 3 11 thermal EMF minimizing DC voltage measurement 3 13 RTDs thermistors and resistors 3 27 thermocouples 3 11 thermistors 3 19 to 3 21 accuracy specifications table A 4 advantages and disadvantages 3 19 connecting 3 21 optimizing measurements 3 24 to 3 27 resistance temperature characteristics 3 20 to 3 21 resistance temperature curve figure 3 20 types
92. surement table 3 26 programmable ground referencing 3 25 programmable open thermocouple detection 3 25 self heating 3 26 to 3 27 thermal EMF 3 27 two wire three wire and four wire measurements 3 25 to 3 26 RTDs 3 14 to 3 19 connecting 3 16 to 3 19 relationship of resistance and temperature 3 15 to 3 16 thermistors 3 19 to 3 21 connecting 3 21 resistance temperature characteristics 3 20 to 3 21 Index National Instruments Corporation I 5 NI 4350 4351 User Manual RTDs 3 14 to 3 18 accuracy specifications table A 3 Callendar Van Dusen coefficients table 3 16 connecting 3 16 to 3 19 four wire RTD measurement figure 3 17 three wire RTD measurement figure 3 18 two wire RTD measurement figure 3 17 definition 3 14 measuring temperature 3 14 to 3 18 optimizing measurements 3 24 to 3 27 relationship of resistance and temperature 3 15 to 3 16 resistance temperature curve figure 3 15 S self heating errors due to 3 26 to 3 27 signal connections B 1 to B 5 using NI 435x ISA USB PXI PCI with TBX 68 table B 3 to B 5 using NI 4350 PCMCIA with CB 27 table B 1 to B 2 signal sources floating signal source 3 4 ground referenced signal source 3 4 software installation 2 1 programming choices 1 4 to 1 6 National Instruments application software 1 4 to 1 5 NI435X instrument driver and NI DAQ 1 5 to 1 6 VirtualBench 1 5 source impedance DC voltage measurement 3 13
93. t Vin 5 V 10 A Input high current Vin 5 V 10 A Output low voltage Iout 8 mA 0 4 V Output high voltage Iout 8 mA 3 8 V Appendix A Specifications NI 4350 4351 User Manual A 10 National Instruments Corporation Power Requirement PCMCIA 130 mA at 5 V ISA 160 mA at 5 V USB High power USB powered peripheral 500 mA PXI 480 mA at 5 V PCI 480 mA at 5 V Power available at I O connector 4 6 V to 5 2 V 1 A ISA PXI PCI 4 6 V to 5 2 V 50 mA USB Physical Dimensions PCMCIA Type II PC Card ISA ISA half size USB 14 6 by 21 3 by 3 8 cm 5 8 by 8 4 by 1 5 in PXI 16 by 10 cm 6 3 by 3 9 in PCI PCI half size I O connector PCMCIA 32 pin female shielded and latched ISA USB PXI PCI 68 pin male shielded and latched Environment Operating temperature 0 to 55 C Storage temperat
94. t change the frequency characteristics of a signal ft feet G gain factor by which a signal is amplified sometimes expressed in decibels GND ground H hardware physical components of a computer system such as the circuit boards plug in boards chassis enclosures peripherals cables and so on Hz hertz unit of frequency Glossary National Instruments Corporation G 5 NI 4350 4351 User Manual I IC integrated circuit IEXx voltage excitation signal in inches interrupt a computer signal indicating that the CPU should suspend its current task to service a designated activity I O input output the transfer of data to from a computer system involving communications channels operator interface instruments and or data acquisition and control interfaces ISA industry standard architecture bus ITS International Temperature Scale K K 1 kelvin a unit of temperature kbytes s a unit for data transfer that means 1 000 or 103 bytes s kS 1 000 samples L LabVIEW laboratory virtual instrument engineering workbench latch digital device that stores the digital data based on a control signal LED light emitting diode Glossary NI 4350 4351 User Manual G 6 National Instruments Corporation M m meter a unit of length M 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
95. ts Corporation Figure 1 1 The Relationship between the Programming Environment NI435X Instrument Drivers NI DAQ and Your Hardware Optional Equipment National Instruments offers a variety of products to use with your NI 435x including cables connector blocks terminal blocks and other accessories as follows Cables and adapters with thermocouple miniconnectors Connector blocks including isothermal connector blocks Cables and cable accessories shielded and ribbon For more specific information about these products refer to your National Instruments catalogue or web site or call the office nearest you NI DAQ Driver Software NI435X Instrument Driver API VirtualBench Visual Basic LabVIEW LabWindows CVI C C NI 4350 4351 Instrument PCMCIA ISA PXI PCI Win95 98 NT USB Win 98 DAQ VI Library Easy I O for DAQ Library Not Recommended National Instruments Corporation 2 1 NI 4350 4351 User Manual Chapter2 Installation and Configuration This chapter describes how to install and configure your NI 435x instrument Software Installation Install your software before you install your NI 435x instrument Refer to the appropriate release notes for specific instructions on the software installation sequence If you are using LabVIEW LabWindows CVI or VirtualBench refer to the release notes for your software After you have installed your software refer to the NI DAQ release n
96. ucers connected to analog channels in the same measurement setup Note Use the 25 A current source for thermistors above 1 k Connecting Your Resistor You can use signal connection techniques described in the sections Connecting Your RTD and Connecting Your Thermistor for any resistor as well The NI 435x accessories the CB 27T and CB 27 for the NI 4350 PCMCIA and the TBX 68T and TBX 68 for the NI 435x ISA USB PXI PCI are designed to be used with RTDs thermistors and resistors Consult your accessory installation guide for instructions on IEX or IEX0 Rt CH CH IEX or IEX0 Iex Chapter 3 NI 435x Operation NI 4350 4351 User Manual 3 22 National Instruments Corporation how to connect your resistors Figures 3 10 and 3 11 show examples of how to use different transducers connected to analog channels in the same measurement setup Figure 3 10 Multiple Transducer Connections to Analog Channels in One Measurement Setup Channels 0 5 IEX or IEX0 Thermistor Cold Junction Thermistor on Accessory Ground Referenced Thermocouple Floating Thermocouple Auto Zero CH5 CH5 CH4 CH4 CH3 CH2 CH3 RTD CH2 CH1 CH1 CH0 CH0 IEX or IEX0 Internal to the NI 435x 2 5 V 20 k Ground Referencing Off Open Thermocouple Detection Off Ground Referencing Off Open Thermocouple Detection On Ground
97. uments Corporation NI 4351 PCI You can install your NI 4351 PCI in any available PCI expansion slot in your computer However to achieve the best noise performance you should leave as much room as possible between the NI 4351 PCI and other boards and hardware The following are general instructions but consult your computer user manual or technical reference manual for specific instructions and warnings 1 Plug in but do not turn on your computer before installing the NI 4351 PCI device The power cord grounds the computer and protects it from electrical damage while you are installing the module Warning To protect both yourself and the computer from electrical hazards the computer should remain off until you finish installing the NI 4351 PCI 2 Remove the top cover or access port to the PCI bus 3 Select any available PCI expansion slot 4 Locate the metal bracket that covers the cut out in the back panel of the chassis for the slot you have selected Remove and save the bracket retaining screw and the bracket cover 5 Touch the metal part of the power supply case inside the computer to discharge any static electricity that might be on your clothes or body Caution The NI 4351 PCI is ESD contamination sensitive Handle the board using the metal bracket or edges 6 Line up the NI 4351 PCI with the 68 pin connector near the cut out on the back panel Slowly push down on the top of the NI 4351
98. uples and the NI 435x instrument and its accessory 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 Chapter 3 NI 435x Operation National Instruments Corporation 3 11 NI 4350 4351 User Manual Thermal EMF When using thermocouples any thermal EMFs other than those at the hot junction where the thermocouple measures the test point temperature and at the cold junction on the accessory will introduce error To minimize thermal EMFs use wires of the same thermocouple type when extending the length of the thermocouple Also minimize temperature gradients in the space enclosing the thermocouple the NI 435x instrument and its accessories Measuring DC Voltage Connecting Your DC Voltage Signal The NI 435x accessories the CB 27T and CB 27 for the NI 4350 PCMCIA and the TBX 68T and TBX 68 for the NI 435x ISA USB PXI PCI are designed to be used with any DC voltage signal Consult your accessory installation guide for instructions on how to connect your voltage signals The NI 435x analog inputs are protected against damage from voltages within 42 VDC in all ranges when powered up and 17 VDC when the NI 435x instrument is powered down You s
99. ure 20 to 70 C National Instruments Corporation B 1 NI 4350 4351 User Manual AppendixB Signal Connections This section explains the signal correlation between your NI 435x and the accessories you might use with it The NI 4350 PCMCIA kit includes a label that you should apply to your CB 27 accessory This label provides the pin correlation between these two devices The following table shows how the screw terminals on the CB 27 correspond to the signal names on the NI 4350 PCMCIA Table B 1 Using the NI 4350 PCMCIA with the CB 27 NI 4350 PCMCIA Signal Name CB 27 Screw Terminal CH0 2 CH0 3 CH1 4 CH1 5 CH2 6 CH2 7 CH3 8 CH3 9 CH4 10 CH4 11 CH5 12 CH5 13 CH6 14 Appendix B Signal Connections National Instruments Corporation B 2 NI 4350 4351 User Manual CH6 15 CH7 16 CH7 17 AGND 1 IEX 18 IEX 19 RSVD1 20 RSVD2 21 DIO0 23 DIO1 24 DIO2 25 DIO3 26 DGND 27 GND 22 Table B 1 Using the NI 4350 PCMCIA with the CB 27 Continued NI 4350 PCMCIA Signal Name CB 27 Screw Terminal Appendix B Signal Connections National Instruments Corporation B 3 NI 4350 4351 User Manual Table B 2 shows how the screw terminals on the TBX 68 connector block and the SH6868 and R6868 cables correspond to the signal names on the NI 435x ISA USB

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