National Instruments NI 4350, User Manual

Page 1: ...NI 4350 User Manual Temperature and Voltage Measurement Instruments NI 4350 User Manual May 1998 Edition Part Number 321566B 01 Copyright 1997 1998 National Instruments Corporation All rights reserved...

Page 2: ...ium 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 Is...

Page 3: ...DUCTS 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...

Page 4: ...Choices 1 4 National Instruments Application Software 1 4 VirtualBench 1 4 NI435X Instrument Driver and NI DAQ 1 5 Optional Equipment 1 6 Chapter 2 Installation and Configuration Software Installatio...

Page 5: ...ction 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 Resistan...

Page 6: ...5 Four Wire RTD Measurement 3 17 Figure 3 6 Three Wire RTD Measurement with a Wheatstone Bridge and a Current Source 3 18 Figure 3 7 Three Wire RTD Measurement 3 18 Figure 3 8 Resistance Temperature...

Page 7: ...tional Instruments Corporation Table 3 5 Guidelines for Resistance Measurement 3 25 Table 3 6 Logic Family Thresholds 3 29 Table B 1 Using the NI 4350 PCMCIA with the CB 27 B 1 Table B 2 Using the NI...

Page 8: ...ument Chapter 3 NI 4350 Operation describes how to use your NI 4350 instrument and includes operation tips on taking measurements with temperature sensors such as thermocouples RTDs and thermistors as...

Page 9: ...og 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...

Page 10: ...I and VirtualBench After you set up your hardware system use either your application software documentation or the NI DAQ documentation to help you write your application If you have a large complicat...

Page 11: ...0 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 4350 instruments contain a 24 bit sigma delta ana...

Page 12: ...instrument used with your computer is a versatile cost effective platform for high resolution measurements Detailed specifications for the NI 4350 instruments are in Appendix A Specifications What Yo...

Page 13: ...ct 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 com...

Page 14: ...ion 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 La...

Page 15: ...he 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...

Page 16: ...cessories as follows Cables and adapters with thermocouple miniconnectors Connector blocks including isothermal connector blocks Cables and cable accessories shielded and ribbon For more specific info...

Page 17: ...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...

Page 18: ...6 Configure your accessory using the NI DAQ Configuration Utility 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 H...

Page 19: ...red 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...

Page 20: ...ff 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 Th...

Page 21: ...t 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 lo...

Page 22: ...0 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 volt...

Page 23: ...propriate to the sensor Choosing a Reading Rate The reading rate is the rate at which your NI 4350 takes a new measurement This rate has a direct relationship with the digital filter built into the AD...

Page 24: ...eve 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 harmo...

Page 25: ...unded or exposed junctions connected to grounded test points and outputs of plug in devices with nonisolated outputs voltage across RTDs thermistors or resistors you may be measuring using the built i...

Page 26: ...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 conc...

Page 27: ...l EMF However just measuring this voltage is not sufficient because connecting the thermocouple to the NI 4350 instrument accessory creates the reference junction or cold junction shown in Figure 3 2...

Page 28: ...nt driver or the DAQ 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...

Page 29: ...ges within 42 VDC in all ranges when powered up and 17 VDC when the NI 4350 instrument is powered down You should never apply voltages above these levels to the inputs Caution To prevent possible safe...

Page 30: ...mocouple 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 4350 instrument When you use the PSH32 TC6 C...

Page 31: ...y 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 thermocou...

Page 32: ...hin 42 VDC in all ranges when powered up and 17 VDC when the NI 4350 instrument is powered down You should never apply voltages above these levels to the inputs Caution To prevent possible safety haza...

Page 33: ...l offset error the NI 4350 instrument may have This is especially useful when the NI 4350 instrument is operating at an ambient temperature other than that of calibration 23 C typical Note When using...

Page 34: ...ibit additional errors To minimize these errors keep the signal source and the NI 4350 instrument and its accessories away from strong AC magnetic sources and minimize the area of the loop formed by t...

Page 35: ...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...

Page 36: ...ical 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 measur...

Page 37: ...only 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 c...

Page 38: ...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 resistan...

Page 39: ...om metal oxides pressed into a small bead disk wafer or other shape sintered at high temperatures and finally coated with epoxy or glass The resulting device exhibits an electrical resistance that var...

Page 40: ...o 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 RT...

Page 41: ...r can be approximated relatively accurately with the Steinhart Hart equation Where T K is the temperature in kelvin equal to T C 273 15 and Rt is the resistance of the thermistor The coefficients a b...

Page 42: ...bed in the sections Connecting Your RTD and Connecting Your Thermistor for any resistor as well The NI 4350 accessories the CB 27T and CB 27 for the NI 4350 PCMCIA and the TBX 68T and TBX 68 for the N...

Page 43: ...ent is powered down IEX 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 Internal...

Page 44: ...e 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...

Page 45: ...ce 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 erron...

Page 46: ...n 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...

Page 47: ...ltage 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...

Page 48: ...r requirements you can use external signal conditioning such as electromechanical relay solid state relay opto coupler and so on You can use the digital input lines to trigger analog acquisitions To d...

Page 49: ...ect 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 o...

Page 50: ...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 thresh...

Page 51: ...hermocouple 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...

Page 52: ...3 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...

Page 53: ...ear 0 15 C 35 55 C Filter Setting Temperature Coefficient C C RTD C 10 Hz 50 Hz 60 Hz 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 Thermistor...

Page 54: ...072 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 5 Resistance specifications assume worst case common mode voltage for the given range Specifications imp...

Page 55: ...ssory 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 1V using 1 25 V range filter setting of 60 Hz at 28 C ambient t...

Page 56: ...ge 2 5 V Each input should remain within 2 5 V of ground Over voltage protection ACH 0 8 15 IEX 42 V powered on 17 V powered off Data transfers Interrupts programmed I O Warm up time 30 minutes Amplif...

Page 57: ...CH and ground software selectable Input bias current 500 pA CMR DC 50 Hz 60 Hz 400 Hz Range 2 5 V 80 dB Range 2 5 V 100 dB NMR 50 Hz 60 Hz 400 Hz 100 dB Dynamic Characteristics Bandwidth 20 Hz Step re...

Page 58: ...weak pull up Data transfers Programmed I O Bus Interface Type Slave Plug and Play Power Requirement PCMCIA 130 mA at 5 V ISA 160 mA at 5 V USB High power USB powered peripheral 500 mA Level Minimum Ma...

Page 59: ...hysical 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 I O connector PCMCIA 32 pin female shielded and latched ISA and USB 68 pin male shielded and...

Page 60: ...ludes 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...

Page 61: ...Corporation B 2 NI 4350 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 Continu...

Page 62: ...TBX 68 SH6868 and R6868 have a one to one correlation to pins on the NI 4350 ISA Table B 2 Using the NI 4350 ISA and USB with the TBX 68 NI 4350 ISA and USB Signal Name TBX 68 Screw Terminal CH0 68 CH...

Page 63: ...ion 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 12 IEX 45 DIO0 7 DIO1 6 DIO2 5 DIO3 4 DIO4 37 DIO5 3 Table B 2 Using the NI 4350 ISA and...

Page 64: ...5V 8 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 The current available may be limited to less than 50 mA typical when using the NI 4350 USB Table B 2 Using the...

Page 65: ...s does not answer your questions we offer fax and telephone support through our technical support centers which are staffed by applications engineers Electronic Services Bulletin Board Support Nationa...

Page 66: ...t 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...

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Page 68: ...__ Base I O address of other boards _____________________________________________________ DMA channels of other boards ______________________________________________________ Interrupt level of other b...

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Page 70: ...1 NI 4350 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 1...

Page 71: ...easurement AWG American Wire Gauge B b bit one binary digit either 0 or 1 B byte eight related bits of data an eight bit binary number Also used to denote the amount of memory required to store one by...

Page 72: ...rs 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 com...

Page 73: ...ry 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 that chang...

Page 74: ...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 l...

Page 75: ...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 hard...

Page 76: ...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 rms root me...

Page 77: ...annels in the output group update rate the rate at which the measurement data is updated USB Universal Serial Bus V V volt an electic unit VI virtual instrument 1 a combination of hardware and or soft...

Page 78: ...teristics A 5 to A 6 physical A 9 power requirements A 8 auto zero optimization DC voltage measurement 3 9 RTDs thermistors and resistors 3 23 to 3 24 thermocouples 3 9 B bulletin board support C 1 bu...

Page 79: ...referenced signal source 3 4 ground referencing programmable optimizing measurements DC voltage measurement 3 12 RTDs thermistors and resistors 3 23 to 3 24 thermocouples 3 9 purpose and use 3 4 to 3...

Page 80: ...t ranges 3 11 optimizing measurements 3 12 to 3 13 digital inputs and outputs 3 27 to 3 29 measurement mode selection 3 1 programmable ground referencing 3 4 to 3 5 programmable open thermocouple dete...

Page 81: ...uple detection See open thermocouple detection programmable R range selection for measurement mode 3 1 to 3 2 reading rate selection 3 2 to 3 3 determining reading rate per channel note 3 3 digital fi...

Page 82: ...s application software 1 4 NI435X instrument driver and NI DAQ 1 5 to 1 6 VirtualBench 1 4 to 1 5 source impedance DC voltage measurement 3 13 specifications accuracy A 1 to A 5 calculation examples A...

Page 83: ...sistance temperature curve figure 3 19 types of thermistors 3 18 to 3 19 thermocouples for measuring temperature 3 6 to 3 11 accuracy specifications table A 1 to A 2 cold junction compensation options...