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Chapter 4

Theory of Operation

© National Instruments Corporation

4-5

DAQCard-500 User Manual

Multichannel (Scanned) Data Acquisition

You can perform multichannel data acquisition by enabling scanning during data acquisition.
Multichannel scanning is controlled by a scan counter.

For scanning operations, the DAQCard-500 decrements from the highest numbered channel
(selected by the user) through channel 0 and then repeats the sequence.  Any number of channels
from 2 to 8 can be scanned.

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
multiplexer and operational amplifier.  After the input multiplexer is 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 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.

Digital I/O Circuitry

The DAQCard-500 has eight digital I/O lines that are TTL-compatible.  Pins DIN<0..3> of the
I/O connector are digital input lines, and pins DOUT<0..3> are digital output lines.  These lines
are monitored or driven by the Digital Input Register or the Digital Output Register, respectively.
Reading the Digital Input Register returns the current state of DIN<0..3> lines.  Writing to the
Digital Output Register drives the new value onto the DOUT<0..3> lines.  Figure 4-4 shows a
diagram of this circuitry.

Summary of Contents for DAQCard-500

Page 1: ... Copyright 1995 1996 National Instruments Corporation All Rights Reserved DAQCard 500 User Manual Multifunction I O Card for Type II PCMCIA Bus January 1996 Edition Part Number 371918A 01 ...

Page 2: ...Belgium 02 757 00 20 Canada Ontario 519 622 9310 Canada Québec 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 Japan 03 5472 2970 Korea 02 596 7456 Mexico 95 800 010 0793 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...

Page 3: ...r any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE ...

Page 4: ...r 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 Instr...

Page 5: ...ng 1 4 Chapter 2 Installation and Configuration 2 1 Installation 2 1 Configuration 2 2 Analog Input Configuration 2 3 Digital I O Configuration 2 3 Counter Configuration 2 3 Chapter 3 Signal Connections 3 1 I O Connector 3 1 Signal Connection Descriptions 3 2 Analog Input Signal Connections 3 2 Analog Input Signal Connection Considerations 3 3 Types of Signal Sources 3 3 Ground Referenced Signal S...

Page 6: ...gle Channel Data Acquisition 4 4 Multichannel Scanned Data Acquisition 4 5 Data Acquisition Rates 4 5 Digital I O Circuitry 4 5 Timing I O Circuitry 4 6 Appendix A Specifications A 1 Appendix B Differences between the DAQCard 700 and the DAQCard 500 B 1 Appendix C Custom Cable Design C 1 Appendix D PC Card Questions and Answers D 1 Appendix E Power Management Modes E 1 Appendix F PSH27 50F Signal ...

Page 7: ...ure 3 6 Frequency Measurement Application 3 9 Figure 3 7 General Purpose Timing Signals 3 10 Figure 4 1 DAQCard 500 Block Diagram 4 1 Figure 4 2 PCMCIA I O Interface Circuitry Block Diagram 4 2 Figure 4 3 Analog Input and Data Acquisition Circuitry Block Diagram 4 3 Figure 4 4 Digital I O Circuitry Block Diagram 4 6 Figure 4 5 Timing I O Circuitry Block Diagram 4 7 Figure 4 6 Counter Block Diagram...

Page 8: ...ns lists the specifications of the DAQCard 500 Appendix B Differences between the DAQCard 700 and the DAQCard 500 contains a summary of differences between the DAQCard 700 and the DAQCard 500 that may be relevant to you if you are a current DAQCard 700 user Appendix C Custom Cable Design describes the pin connections on the DAQCard 500 which you will need to use only if you are designing your own ...

Page 9: ... read It gives an overview of the SCXI system and contains the most commonly needed information for the modules chassis and software Your SCXI user manuals If you are using SCXI read these manuals next for detailed information about signal connections and module configuration They also explain in greater detail how the module works and contain application hints Your DAQ hardware user manuals These...

Page 10: ...s manual contains detailed information for the register level programmer DAQCard 500 Register Level Programmer Manual This manual is available from National Instruments by request If you are using NI DAQ LabVIEW or LabWindows CVI you should not need the register level programmer manual Using NI DAQ LabVIEW or LabWindows CVI is as easy and as flexible as using the low level programming described in...

Page 11: ...isted 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 weight of the DAQCard 500 coupled with its low power consumption make this board ideal for use in portable computers making remote data acquisition practical The board requires very little power when operating and ha...

Page 12: ...as 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 Instr...

Page 13: ...gh level functions are streaming data to disk or acquiring a certain number of data points An example 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 at their peak performance NI DAQ also internally addresses many of the complex issues between the comput...

Page 14: ...vel programming and can save weeks of development time Optional Equipment Listed below are some of the optional accessories that work with the DAQCard 500 New accessories are always being added to our product family See your National Instruments catalog or call the National Instruments office nearest you for more information about optional equipment PR27 30F I O connector with 5 m or 1 m connector...

Page 15: ... you are using the CB 27 attach the label to the inside cover This label identifies the DAQCard 500 signal connections for the CB 27 The DAQCard 500 has two connectors a 68 pin PCMCIA bus connector on one end and a 27 pin I O connector on the other 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 i...

Page 16: ...cumentation to install and configure the software If you are using NI DAQ for PC compatibles or NI DAQ for NEC PC 9800 Series computers refer to your NI DAQ release notes Find the installation and system configuration section for your operating system and follow the instructions given there If you are using NI DAQ for Macintosh refer to the NI DAQ documentation Find the installation and system con...

Page 17: ...el programmer refer to the DAQCard 500 Register Level Programmer Manual Analog Input Configuration The DAQCard 500 is always configured as follows Single ended input mode referenced to analog ground 5 V analog input range Digital I O Configuration The DAQCard 500 always uses one 4 bit digital output port and one 4 bit digital input port Counter Configuration You can use the MSM82C54 counter timers...

Page 18: ... the signal names and pin numbers are the same Warning Connections that exceed any of the maximum ratings of input or output signals on the DAQCard 500 can damage the DAQCard 500 and your computer This includes connecting any power signals to ground and vice versa National Instruments is NOT liable for any damages resulting from such signal connections 2 4 6 8 10 12 14 16 18 11 13 15 17 20 22 24 2...

Page 19: ...mon ground tie in point for all digital signals 22 CLK1 Clock Input of Counter 1 This signal is the clock input of counter 1 23 OUT1 Output of Counter 1 This signal outputs the programmed waveform of counter 1 24 GATE2 Gate Input of Counter 2 This signal controls the starting interruption and restarting of counter 2 25 CLK2 Clock Input of Counter 2 This signal is the clock input of counter 2 26 OU...

Page 20: ...em ground Nonisolated outputs of instruments and devices that plug into the building power system fall into this category The difference in ground potential between two instruments connected to the same building power system is typically between 1 and 100 mV but can be much higher if power distribution circuits are not properly connected Floating Signal Sources A floating signal source is one that...

Page 21: ...truments with differential inputs A floating measurement system will float to the level of the signals being measured Analog Input Connections The analog input connections on the DAQCard 500 are single ended They are measured with respect to one common ground The input signals are tied to the positive input of an operational amplifier that is referenced to this common ground Figure 3 2 shows how t...

Page 22: ... 500 Signal Mux AIGND 2 3 4 5 9 1 DAQCard 500 Signal Mux AIGND 2 3 4 5 9 1 DAQCard 500 Signal Ground Current Mux AIGND 2 3 4 5 9 1 DAQCard 500 NOT RECOMMENDED Figure 3 2 DAQCard 500 Analog Input Connections Digital I O Signal Connections Pins 12 through 19 of the I O connector are digital I O signal pins Pins 12 through 15 are digital input pins Pins 16 through 19 are digital output pins Pin 27 is...

Page 23: ... example of connections to the digital input and output ports Digital input applications include receiving TTL signals and sensing external device states such as the switch in Figure 3 3 Digital output applications include sending TTL signals and driving external devices such as the LED shown in Figure 3 3 TTL Signal Digital Input Port Digital Output Port 12 DIN0 27 DGND I O Connector DAQCard 500 ...

Page 24: ...s If you need to program this chip directly refer to the optional DAQCard 500 Register Level Programmer Manual for the programming sequence needed to enable this input Figure 3 4 shows the timing requirements for the EXTCONV input An A D conversion is initiated by a rising edge on the EXTCONV The data from this conversion is latched into the FIFO memory within 20 µs The EXTCONV input is a TTL comp...

Page 25: ...nections for a typical event counting operation in which a switch is used to gate counter 2 on and off 100 kΩ 1 MHz Switch DGND Counter 2 OUT CLK GA TE 5 V 20 27 I O Connector DAQCard 500 26 24 25 Figure 3 5 Event Counting Application with External Switch Gating Use level gating to measure pulse width Apply the pulse to be measured to the GATE2 input Load the counter with the known count and progr...

Page 26: ...iod Figure 3 6 shows the connections for a frequency measurement application You could also use counter 1 to generate the gate signal in this application 100 kΩ 1 MHz Gate Source DGND Counter 2 OUT CLK GA TE 5 V 20 27 I O Connector DAQCard 500 26 24 25 Figure 3 6 Frequency Measurement Application The CLK and OUT signals for counter 1 are available at the I O connector The GATE CLK and OUT signals ...

Page 27: ...40 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 outc 100 ns minimum 30 ns minimum 40 ns minimum 50 ns minimum 50 ns minimum 100 ns maximum 50 ns minimum 100 ns maximum t outg t outc t gwh t gwl t gh t gsu t pwl t pwh t sc clock period clock high lev...

Page 28: ...put wires to screw terminals on the connector block and therefore to the DAQCard 500 I O connector The CB 27 is useful for the initial prototyping of an application or in situations in which the DAQCard 500 interconnections are frequently changed After you develop a final field wiring scheme however you may want to develop your own cable Refer to Appendix C Custom Cable Design for information and ...

Page 29: ...n Figure 4 1 shows a functional overview of the DAQCard 500 From A D FIFO I O Connector OUT0 EXTCONV 1 MHz 4 4 12 V To Analog Circuit 5 V 5 V 12 V 12 Bit Sampling ADC 16 Word FIFO PCMCIA I O Channel Interface Buffer PCMCIA I O Channel Scanning Counter A D Timing MSM82C54 Interrupt Interface Digital I O DC DC Converter To Analog Circuit Input Mux 8 Channel Single Ended 8 5 1 V 5 1 V GATE2 CLK 1 2 O...

Page 30: ... this 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 interface circuitry consists of an address bus a data bus interrupt lines and several control and support signals The components making up the DAQCard 500 PCMCIA I O channel interface circuitry are shown...

Page 31: ... 12 Bit Sampling ADC PCMCIA I O Channel Interface I O Connector Scanning Counter 3 A D Timing MSM82C54 Interrupt Interface 1 MHz Input Mux 8 Channel Single Ended 12 8 16 Word FIFO Sign Extension Figure 4 3 Analog Input and Data Acquisition Circuitry Block Diagram Analog Input Circuitry The analog input circuitry consists of an input multiplexer a buffer and a 12 bit sampling ADC The 12 bit output ...

Page 32: ...two types of data acquisition single channel data acquisition and multichannel scanned data acquisition Scanned data acquisition uses a counter to automatically switch between analog input channels during data acquisition Data acquisition timing consists of signals that initiate a data acquisition operation and generate scanning clocks One of the three counters of the onboard MSM82C54 is reserved ...

Page 33: ...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 are listed in Appendix A Specifications These settling time specifications assume that voltage levels on ...

Page 34: ...rcuitry Block Diagram Timing I O Circuitry The DAQCard 500 uses an MSM82C54 counter timer integrated circuit for data acquisition timing and for general purpose timing I O functions Counters 1 and 2 of the MSM82C54 are available for general use but counter 0 is used internally for data acquisition timing The gate signal of counter 1 is internally pulled up and is always active Figure 4 5 shows a b...

Page 35: ...in Figure 4 5 counter 0 is used for data acquisition timing and counters 1 and 2 are free for general use All three counter timers can be programmed to operate in several useful timing modes The programming and operation of the MSM82C54 is presented in detail in the optional DAQCard 500 Register Level Programmer Manual The MSM82C54 for counter 0 uses a 1 MHz clock generated from the onboard oscill...

Page 36: ...ments Corporation 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 two and their GATE CLK and OUT pins are labeled GATE N CLK N and OUT N where N is the counter number ...

Page 37: ... on 25 V powered off Inputs protected ACH 0 7 FIFO buffer size 16 samples Data transfers Interrupts programmed I O Transfer Characteristics Relative accuracy 1 5 LSB typ 2 5 LSB max DNL 0 7 LSB typ 1 LSB max INL 0 7 LSB typ 1 LSB max No missing codes 12 bits guaranteed Offset error After software calibration 1 LSB Before software calibration 8 LSB typ 12 LSB max Gain error relative to calibration ...

Page 38: ...bits Compatibility TTL gate and source pulled high with 100 k resistors Base clocks available 1 MHz Base clock accuracy 0 01 Max source frequency 10 MHz Min source pulse duration 50 ns Min gate pulse duration 50 ns Data transfers Programmed I O Bus Interface Type Slave Power Requirement 5 VDC 5 60 mA in operational mode 20 mA in power down mode Note These power usage figures do not include the pow...

Page 39: ...mming differences refer to the DAQCard 500 Register Level Programmer Manual Functionality DAQCard 700 DAQCard 500 FIFO read One 16 bit word Two 8 bit words FIFO buffer size 512 samples 16 samples Maximum sample rate 100 kS s 25 kS s Maximum input voltage rating 30 V 25 V ADC calibration Software calibration Software calibration Timer chip MSM82C54 MSM82C54 Maximum timer source frequency 10 MHz 10 ...

Page 40: ...e the pin assignment in Figure C 1 only for custom cable design If you are using the National Instruments 27 30F cable you should use the pin assignment shown in Figure 3 1 The other end of the cable uses a 30 pin insulation displacement male ribbon cable header connector National Instruments uses a polarized keyed connector to prevent inadvertent upside down connection to the CB 27 Recommended ma...

Page 41: ...7 18 19 20 21 22 23 24 25 26 DGND OUT2 CLK2 GATE2 OUT1 CLK1 DGND 1MHZ DOUT3 DOUT2 DOUT1 DOUT0 DIN3 DIN2 DIN1 DIN0 EXTCONV 5 V ACH7 ACH6 ACH5 ACH4 ACH3 ACH2 ACH1 ACH0 27 AIGND key Figure C 1 DAQCard 500 I O Connector Pin Assignments Note Use this pin assignment figure ONLY if you are designing custom made cables for your DAQCard 500 ...

Page 42: ...MCIA 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 2 0 or later Operation 1 My PC Card works when inserted before power on time but it does not work when hot inserted What is wrong You may have an interrupt conflict If you have a utility such as MSD EXE run it to determine the allocate...

Page 43: ...ed For example if you run such a memory utility and it tells you that physical addresses C0000 to C9FFF are being used for ROM access then you know that C8000 D3FFF is an invalid range for Card Services and should be changed to CA000 D3FFF 3 How can I find usable I O addresses Finding usable I O addresses is done by trial and error Of the three resources used memory I O interrupts I O conflicts wi...

Page 44: ...Services When you have determined what memory is available for Card Services reinstall your memory manager and make the necessary changes to provide Card Services with the memory needed We suggest that you use the minimum amount of memory for Card Services namely 4 to 12 KB which frees more memory for the memory manager Resource Conflicts 1 How do I resolve conflicts between my memory manager and ...

Page 45: ...ndows and is installed whenever you install NI DAQ Typically the analog supplies are not reduced to zero negligible power is supplied to the analog circuits This mode draws about 20 mA from the 5 V supply about 100 mW Table E 1 shows the effects of different power management modes on the DAQCard 500 circuits Table E 1 DAQCard 500 Power Management Modes Normal Mode Power Down Mode Analog Input Func...

Page 46: ...t pin numbers refer to Figure F 1 Note Use of the PSH27 50F D1 cable with the DAQCard 500 is not recommended because the PSH27 50F D1 design is optimized for use with the DAQCard DIO 24 ACH0 ACH1 ACH2 ACH3 ACH4 ACH5 ACH6 ACH7 5 V EXTCONV DIN0 DIN1 DIN2 DIN3 DOUT0 DOUT1 DOUT2 DOUT3 1 MHz DGND CLK1 OUT1 GATE2 CLK2 OUT2 AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND A...

Page 47: ...earest 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 9422 03 9 879 9179 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Canada Ontario 519 622 9310 519 622 9311 Canada Quebec 514 694 8521 514 694 4399 Denmark 45 76 26 00 45...

Page 48: ...fficiently 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 Speed MHz RAM MB Display adapter Mouse yes no Other adapters installed Hard disk capacity MB Brand Instruments used Nati...

Page 49: ..._________________________________________ Microprocessor _________________________________________________ Clock Frequency _________________________________________________ Type of Video Board Installed Operating System Operating System Version _________________________________________________ PCMCIA Software _________________________________________________ PCMCIA Software Version _______________...

Page 50: ...ser Manual Edition Date January 1996 Part Number 371918A 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 describe the errors Thank you for your help Name Title Company Address Phone Mail to Technical Publications Fax to Technical Publications National Instruments Corporation National Instruments Corpor...

Page 51: ...G American Wire Gauge C Celsius CE card enable signal CLK clock input signal CMOS complementary metallic oxide semiconductor CMRR common mode rejection ratio CTR counter D A digital to analog DAQ data acquisition DAVAIL data available signal DC direct current DGND digital ground signal DIN digital input signal DOUT digital output signal EISA Extended Industry Standard Architecture EXTCONV external...

Page 52: ...signal PCMCIA Personal Computer Memory Card International Association RD read rms root mean square S samples s seconds SCXI Signal Conditioning eXtensions for Instrumentation TTL transistor transistor logic V volts VCC positive supply voltage from the PCMCIA bus usually 5V VDC volts direct current VIH volts input high VIL volts input low Vin volts in VOH volts output high VOL volts output low WR w...

Page 53: ... 3 to 3 4 types of signal sources 3 3 analog input specifications amplifier characteristics A 1 dynamic characteristics A 1 input characteristics A 1 stability A 1 transfer characteristics A 1 asterisk indicating active low signal 3 2 B bus interface specifications A 2 C cables CB 27 termination accessory 3 11 custom cable design 3 11 C 1 installation 2 1 optional equipment 1 4 PR27 30F 2 1 Card a...

Page 54: ... x xi organization of manual ix related documentation xi DOUT 0 3 signal description 3 2 digital I O circuitry 4 5 pin assignments 3 1 C 2 dynamic characteristics analog input A 1 E environment specifications A 2 equipment optional 1 4 event counting 3 8 event counting application illustration 3 8 EXTCONV signal description 3 2 pin assignment 3 1 C 2 timing illustration 3 7 F floating measurement ...

Page 55: ... PC Card questions and answers configuration D 1 operation D 1 resource conflicts D 3 resources D 2 to D 3 physical specifications A 2 pin assignments analog input signals 3 2 digital I O signals 3 5 I O connector illustration 3 1 C 1 timing signals 3 7 power management modes E 1 power specifications A 2 PR27 30F I O connector See connectors programming register level 1 4 PSH27 50F signal connecti...

Page 56: ...quirements A 2 timing I O A 2 square wave generation 3 8 stability analog input A 1 system noise A 1 T technical support G 1 theory of operation analog input circuitry 4 3 to 4 4 data acquisition timing circuitry 4 4 to 4 5 data acquisition rates 4 5 multichannel data acquisition 4 5 single channel data acquisition 4 4 digital I O circuitry 4 5 to 4 6 PC Card I O channel interface circuitry 4 2 to...

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