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National Instruments 700 Скачать руководство пользователя страница 43

Theory of Operation

Chapter 4

DAQCard-700 User Manual

4-6

© National Instruments Corporation

Data Acquisition Rates

The maximum data acquisition rate (number of samples per second) is determined by the
conversion period of the ADC plus the acquisition time of its track-and-hold stage. During
multichannel scanning, the data acquisition rate is further limited by the settling time of the input
multiplexers and operational amplifier. After the input multiplexers are switched, the amplifier
must be able to settle to the new input signal value to within 12-bit accuracy before an A/D
conversion is performed, or 12-bit accuracy cannot not be achieved.

If your chosen data acquisition rate does not allow the specified settling time, the analog input
circuitry may not perform at 12-bit accuracy. Furthermore, if the maximum data acquisition rate
is exceeded, A/D conversions may be lost. The maximum data acquisition rate and settling time
specifications at various input ranges are listed in Appendix A, Specifications.

These settling time specifications assume that voltage levels on all the channels included in the
scan sequence are within range and are driven by low-impedance sources. Signal levels outside
the ranges on the channels included in the scan sequence adversely affect the input settling time.
Similarly, greater settling time may be required for channels driven by high-impedance signal
sources.

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Содержание 700

Страница 1: ...Copyright 1994 1996 National Instruments Corporation All Rights Reserved DAQCard 700 User Manual Multifunction I O Board for the PCMCIA Bus January 1996 Edition Part Number 320676C 01...

Страница 2: ...elgium 02 757 00 20 Canada Ontario 519 622 9310 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 90 527 2321 France 1 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Italy 02 48301892 Japa...

Страница 3: ...damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS...

Страница 4: ...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 an...

Страница 5: ...ramming 1 4 Unpacking 1 4 Chapter 2 Installation and Configuration 2 1 Installation 2 1 Configuration 2 2 Analog I O Configuration 2 3 Analog Input Mode 2 3 RSE Input 2 4 DIFF Input 2 4 Digital I O Co...

Страница 6: ...ng Signal Connections 3 14 Cabling 3 18 Chapter 4 Theory of Operation 4 1 Functional Overview 4 1 PCMCIA I O Channel Interface Circuitry 4 2 Analog Input and Data Acquisition Circuitry 4 3 Analog Inpu...

Страница 7: ...ns 3 13 Figure 3 7 EXTCONV Signal Timing 3 14 Figure 3 8 Event Counting Applications with External Switch Gating 3 15 Figure 3 9 Frequency Measurement Application 3 16 Figure 3 10 General Purpose Timi...

Страница 8: ...r as well as typical cable setups Chapter 4 Theory of Operation includes an overview of the DAQCard 700 and explains the operation of each functional unit making up the DAQCard 700 Appendix A Specific...

Страница 9: ...0 7 stands for ACH0 through ACH7 Abbreviations acronyms metric prefixes mnemonics symbols and terms are listed in the glossary National Instruments Documentation The DAQCard 700 User Manual is one pie...

Страница 10: ...on The following documents contain information that you may find helpful as you read this manual Your NI DAQ software documentation Your computer operating manual which explains how to insert cards in...

Страница 11: ...ry function listed on the data sheet for our DAQ hardware Using NI DAQ you can quickly and easily start your application without having to program the card on the register level The small size and wei...

Страница 12: ...ditional programming languages Both packages include extensive libraries for data acquisition instrument control data analysis and graphical data presentation LabVIEW features interactive graphics a s...

Страница 13: ...mple of a low level function is writing directly to registers on the DAQ device NI DAQ does not sacrifice the performance of National Instruments DAQ devices because it lets multiple devices operate a...

Страница 14: ...r using NI DAQ LabVIEW or LabWindows CVI to program your National Instruments DAQ hardware Using the NI DAQ LabVIEW or LabWindows CVI software is as easy and as flexible as register level programming...

Страница 15: ...her end Insert the PCMCIA bus connector into any available Type II PCMCIA slot until the connector is seated firmly Notice that the card is keyed so that it can be inserted only one way If your comput...

Страница 16: ...pletely software configurable refer to your software documentation to install and configure the software If you are using NI DAQ for PC compatibles refer to the NI DAQ release notes Find the installat...

Страница 17: ...nd shows the default settings Table 2 1 Analog I O Settings Parameter Configuration Analog Input Polarity Bipolar 10 V default setting Bipolar 5 V Bipolar 2 5 V Analog Input Mode Referenced single end...

Страница 18: ...d to a common ground point that is also tied to the DAQCard 700 analog input ground The RSE configuration is useful for measuring floating signal sources See the Types of Signal Sources section of Cha...

Страница 19: ...gital output port and one 8 bit digital input port Counter Configuration You can use the MSM82C54 counter timers for general purpose applications such as pulse and square wave generation event countin...

Страница 20: ...ttached to the ribbon cable that extends from the PCMCIA slot when the card is installed and the cable is connected Warning Connections that exceed any of the maximum ratings of input or output signal...

Страница 21: ...33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 DOUT3 DOUT2 DOUT1 DOUT0 DIN7 DIN6 DIN5 DIN4 DIN3 DIN2 DIN1 DIN0 NC NC DGND ACH15 ACH7 ACH14 ACH6 ACH13 ACH5 ACH12 ACH4 ACH2 ACH1 ACH0 ACH9 ACH3 A...

Страница 22: ...input of the external interrupt signal 40 EXTCONV Input External Control This pin is used for input of the external control signal to trigger A D conversions 41 OUT0 Output Counter 0 Output This pin...

Страница 23: ...ch signal connections Types of Signal Sources When configuring the input mode of the DAQCard 700 and making signal connections you should first determine whether the signal source and the measurement...

Страница 24: ...You should determine from your computer documentation whether any of the power connections are tied to the building power system ground Ground Referenced Measurement System A ground referenced measure...

Страница 25: ...DAQCard 700 ADC measures this output voltage when it performs A D conversions Single Ended Mode Although the instrumentation amplifier on the DAQCard 700 is actually bypassed in single ended mode the...

Страница 26: ...analog input signals are referenced to one common ground The input signals are tied to the positive input of an operational amplifier that is referenced to their common ground point When the DAQCard...

Страница 27: ...Each input signal is tied to the positive input of the instrumentation amplifier and its reference signal or return is tied to the negative input of the instrumentation amplifier When the DAQCard 700...

Страница 28: ...renced signal source to a DAQCard 700 card configured for DIFF input Ground Referenced Signal Source Common Mode Noise Ground Potential and so on Input Multiplexers Instrumentation Amplifier Vm Measur...

Страница 29: ...rrent Return Paths ACH 8 15 ACH 0 7 AIGND Figure 3 5 Differential Input Connections for Floating Sources The 100 k resistors shown in Figure 3 5 create a return path to ground for the bias currents of...

Страница 30: ...ifier can reject common mode noise pickup in the leads connecting the signal sources to the DAQCard 700 The common mode input range of the DAQCard 700 instrumentation amplifier is defined as the magni...

Страница 31: ...ut rating 5 5 V with respect to DGND 0 5 V with respect to DGND Digital input compatibility TTL compatible Input current high or low level 1 mA Digital output compatibility TTL compatible Output curre...

Страница 32: ...cuitry that draws up to 1 A Pin 49 is connected to a 1 A resettable fuse on the card The actual current available from this signal may be less than 1 A depending on the computer Notice also that any c...

Страница 33: ...ime conversions If you need to program this chip directly refer to the optional DAQCard 700 Register Level Programmer Manual for the programming sequence needed to enable this input Figure 3 7 shows t...

Страница 34: ...unt rising or falling edges applied to any of the MSM82C54 CLK inputs You can then read the counter value to determine the number of edges that have occurred You can gate counter operation on and off...

Страница 35: ...known duration In this case program the counter to count falling edges at the CLK input while the gate is applied The frequency of the input signal then equals the count value divided by the gate per...

Страница 36: ...V maximum IOH output source current at VOH 2 5 mA maximum IOL output sink current at VOL 2 5 mA maximum CLK V IH V IL V IH V IL t sc t pwh t gsu t gh t gwh GATE t outg OUT V OH V OL t pwl t gwl t out...

Страница 37: ...position polarized ribbon socket connector with strain relief National Instruments uses a polarized keyed connector to prevent inadvertent upside down connections to the DAQCard 700 Recommended manuf...

Страница 38: ...tional overview of the DAQCard 700 FROM A D FIFO CLK 1 2 OUT 0 2 GATE 0 2 I O Connector OUT0 EXTCONV 3 3 8 8 12 V To Analog Circuit 5 V 5 V 12 V 12 Bit Sampling ADC 512 Word FIFO PCMCIA I O Channel In...

Страница 39: ...chapter The theory of operation for the data acquisition circuitry is included with the discussion of the analog input circuitry PCMCIA I O Channel Interface Circuitry The PCMCIA I O channel interfac...

Страница 40: ...he direction of data transfer on the bi directional data lines based on whether the transfer is a read or write The interrupt control circuitry routes any enabled interrupts to the IREQ line which is...

Страница 41: ...tiplexers switches between eight differential pairs channels 0 and 8 1 and 9 and so on With the input multiplexer stage input overvoltage protection of 30 V is available powered on or off The DAQCard...

Страница 42: ...e counter 0 output OUT0 of the MSM82C54 onboard counter timer chip on the DAQCard 700 or by a low to high transition on EXTCONV input The sample interval timer is a 16 bit down counter that uses the o...

Страница 43: ...med or 12 bit accuracy cannot not be achieved If your chosen data acquisition rate does not allow the specified settling time the analog input circuitry may not perform at 12 bit accuracy Furthermore...

Страница 44: ...Digital Output Register respectively Reading the Digital Input Register returns the current state of DIN 0 7 lines Writing the Digital Output Register drives the new value onto DOUT 0 7 lines The ext...

Страница 45: ...T2 Figure 4 5 Timing I O Circuitry Block Diagram The MSM82C54 contains three independent 16 bit counter timers and one 8 bit Mode Register As shown in Figure 4 5 counter 0 can be used for data acquisi...

Страница 46: ...K GATE OUT Figure 4 6 Counter Block Diagram Each counter has a clock input pin a gate input pin and an output pin labeled CLK GATE and OUT respectively The MSM82C54 counters are numbered zero through...

Страница 47: ...ge signal common mode Each input should remain within 9 5 V of AIGND in Diff mode Overvoltage protection 30 V powered on 30 V powered off Inputs protected ACH 0 15 FIFO buffer size 512 samples Data tr...

Страница 48: ...nd 8 output Compatibility TTL Digital logic levels Level Min Max Input low voltage 0 V 0 8 V Input high voltage 2 V 5 V Input low current Vin 0 V 50 A Input high current Vin 5 V 1 A Output low voltage...

Страница 49: ...in power down mode Note These power usage figures do not include the power used by external devices that you have connected to the fused supply present on the I O connector Physical PC Card type Type...

Страница 50: ...ments VIs for the PC LPM 16 typically work with the DAQCard 700 without modification The following table summarizes the significant differences Functionality PC LPM 16 DAQCard 700 FIFO read Two 8 bit...

Страница 51: ...turer of your computer or of your PCMCIA adapter and request the latest Card and Socket PCMCIA driver Our NI DAQ software will work with any Card and Socket Service driver that is compliant to version...

Страница 52: ...use by Card Services 2 How do I determine all of the memory that Card Services can use One way to find out which memory addresses Card Services can use is to run a utility such as MSD EXE that scans...

Страница 53: ...ory manager by commenting it out of the CONFIG SYS file Next you can rerun the memory utility Memory managers often consume an enormous amount of memory and you will need to determine what memory is r...

Страница 54: ...d to the analog circuits This mode draws about 70 mA from the 5 V supply about 350 mW Table D 1 shows the effects of different power management modes on the DAQCard 700 circuits Table D 1 DAQCard 700...

Страница 55: ...rest branch office You may fax questions to us at any time Corporate Headquarters 512 795 8248 Technical support fax 800 328 2203 512 794 5678 Branch Offices Phone Number Fax Number Australia 03 9 879...

Страница 56: ...iciently 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 N...

Страница 57: ..._______ Other Products Computer Make and Model _________________________________________________ Microprocessor _________________________________________________ Clock Frequency ______________________...

Страница 58: ...er Manual Edition Date January 1996 Part Number 320676C 01 Please comment on the completeness clarity and organization of the manual If you find errors in the manual please record the page numbers and...

Страница 59: ...e BCD binary coded decimal C Celsius CE card enable signal CLK clock input signal CMOS complementary metallic oxide semiconductor CMRR common mode rejection ratio D A digital to analog DAQ data acquis...

Страница 60: ...renced single ended OUT output signal PCMCIA Personal Computer Memory Card International Association RAM random access memory RMA Return Material Authorization rms root mean square S samples s seconds...

Страница 61: ...recommended input configurations 3 7 single ended connections 3 7 to 3 8 single ended input mode 3 6 types of measurement systems 3 5 types of signal sources 3 4 to 3 5 analog input specifications A 1...

Страница 62: ...N 0 7 signal 3 3 documentation conventions used in manual x National Instruments documentation x to xi organization of manual ix related documentation xi DOUT 0 7 signal 3 3 E environment specificatio...

Страница 63: ...ocumentation measurement systems floating 3 5 ground referenced 3 5 memory C 2 to C 3 multichannel scanned data acquisition 4 5 N NI DAQ driver software 1 3 O operation of DAQCard 700 See also theory...

Страница 64: ...3 14 to 3 17 event counting applications 3 15 frequency measurement 3 16 illustration 3 17 pulse and square wave generation 3 15 pulse width measurement 3 15 time lapse measurement 3 16 timing specif...

Страница 65: ...ent counting applications 3 15 illustration 3 15 frequency measurement 3 16 illustration 3 16 illustration 3 17 pulse and square wave generation 3 15 pulse width measurement 3 15 time lapse measuremen...

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