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Chapter 4

Theory of Operation

©

National Instruments Corporation

4-11

DAQCard-1200 User Manual

range of 0 to +10 V. A bipolar output gives an output voltage range of ±5 V.
For unipolar output, 0 V output corresponds to a digital code word of 0. For
bipolar output,

–

5 V output corresponds to a digital code word of F800 hex.

One least significant bit (LSB) is the voltage increment corresponding to an
LSB change in the digital code word. For both outputs:

Power-On State

Both analog outputs reach 0 V approximately 110 ms after card insertion.
During this 110 ms period, the output voltage can swing from +2 to

–

5 V.

Caution

Disconnect the analog outputs from the system before inserting the card in the

PC Card slot. This step ensures that you do not damage the system during the 110 ms
before the output reaches 0 V.

DAC Timing

There are two ways you can update the DAC voltages. In the first mode,
the DAC output voltage is updated as soon as you write to the
corresponding DAC. This mode is called the immediate update mode. In
the second mode, the DAC output voltage does not change until a low level
is detected either from counter A2 of the timing circuitry or from
EXTUPDATE*. This mode is useful for waveform generation. These
two modes are software-selectable.

Note

Configure both DACs in either immediate update mode or later update mode. Do not

configure the DACs in a combination of both modes because doing so can result in
premature updates on the waveform generation DAC (whenever the immediate update
DAC is updated). Also, if a waveform generation update occurs between an LSB write and
an MSB write of the DAC in the immediate update mode, you receive an incorrect value
from that DAC until the MSB is written. Both of these effects are minimal at high
waveform update rates.

Note

Delayed update mode is selected by NI-DAQ when a timed, or buffered,

AO operation is configured.

1

LSB

10

4096

------------

V

=

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Содержание DAQPad-1200

Страница 1: ...DAQPad 1200...

Страница 2: ...DAQ DAQCard 1200 User Manual Multifunction I O Card for the PCMCIA Bus DAQCard 1200 User Manual December 2001 Edition Part Number 320936C 01...

Страница 3: ...5 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91 80 535 5406 Israel 03 6393737 Italy 02 413091 Japan 03 5472 2970 Korea 02 3451 3400 Malaysia 603...

Страница 4: ...n 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 outsid...

Страница 5: ...operate the equipment under the FCC Rules Class A Federal Communications Commission This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to part 15...

Страница 6: ...ought for OEMs if also available from an original manufacturer that also markets in the EU or where compliance is not required as for electrically benign apparatus or cables To obtain the DoC for this...

Страница 7: ...Optional Equipment 1 4 Unpacking 1 5 Safety Information 1 5 Chapter 2 Installing and Configuring the DAQCard 1200 Installing the Software 2 1 Installing the Hardware 2 1 Configuring the DAQCard 1200 2...

Страница 8: ...gnals 3 14 Connecting Digital I O Signals 3 15 Port C Pin Connections 3 17 Timing Specifications 3 18 Mode 1 Input Timing 3 19 Mode 1 Output Timing 3 20 Mode 2 Bidirectional Timing 3 20 Connecting Ana...

Страница 9: ...ate 4 11 DAC Timing 4 11 Digital I O 4 12 Chapter 5 Calibration Loading Calibration Constants 5 1 Self Calibration 5 2 External Calibration 5 2 Appendix A Specifications Appendix B Differences among t...

Страница 10: ...up item and select Options from the last dialog box This icon denotes a note which alerts you to important information This icon denotes a caution which advises you of precautions to take to avoid inj...

Страница 11: ...iled information about the DAQ hardware that plugs into or is connected to the computer Use this documentation for hardware installation and configuration instructions specification information about...

Страница 12: ...can easily install the card and begin acquiring data The low power consumption of the DAQCard 1200 makes this card ideal for use in portable computers and makes portable data acquisition practical The...

Страница 13: ...ifications of the DAQCard 1200 are in Appendix A Specifications What You Need to Get Started To set up and use the DAQCard 1200 you need the following items DAQCard 1200 DAQCard 1200 I O cable DAQCard...

Страница 14: ...ou can change platforms with minimal modifications to your code Whether you use LabVIEW Measurement Studio or other ADEs your application uses NI DAQ as illustrated in Figure 1 1 Figure 1 1 The Relati...

Страница 15: ...Studio features a set of ActiveX controls for using National Instruments DAQ hardware These ActiveX controls provide a high level programming interface for building virtual instruments For Visual C de...

Страница 16: ...hazard You can compromise the safety protection built into the product if the product is damaged in any way If the product is damaged return it to NI for repair Do not substitute parts or modify the...

Страница 17: ...are measurements on circuits not derived from MAINS and specially protected internal MAINS derived circuits Installation category II is for measurements performed on circuits directly connected to th...

Страница 18: ...l Installation category IV is for measurements performed at the source of the low voltage 1 000 V installation Examples of category IV are electric meters and measurements on primary overcurrent prote...

Страница 19: ...erly detected Installing the Hardware The following are general installation instructions Consult the computer user manual or technical reference manual for specific instructions and warnings about in...

Страница 20: ...e way Note Be careful not to put strain on the I O cable when inserting it into and removing it from the DAQCard 1200 Always grasp the cable by the connector you are plugging or unplugging Never pull...

Страница 21: ...DAQ User Manual for PC Compatibles Configuring Analog Input At startup the DAQCard 1200 defaults to the following configuration Referenced single ended input mode 5 V AI range Table 2 1 lists the ava...

Страница 22: ...cting the Signals which contains diagrams showing the signal paths for the three modes These three modes are software selectable DIFF Input Mode Four Channels DIFF input mode means that each input sig...

Страница 23: ...in Chapter 3 Connecting the Signals Notice that in RSE mode the return path of the signal is through analog ground at the connector through the AISENSE AIGND pin NRSE Input Mode Eight Channels NRSE in...

Страница 24: ...to FFF hex 4 095 decimal Configuring Digital I O The DAQCard 1200 uses the MSM82C55 programmable peripheral interface PPI This chip provides 24 digital lines in the form of three ports A B and C On p...

Страница 25: ...200 I O connector This connector is attached to the ribbon cable that extends from the PC Card slot when the card is installed and the cable is connected Caution Connections including power signals to...

Страница 26: ...PC7 PC5 PC3 PC1 PB7 PB5 PB3 PB1 PA7 PA5 PA3 PA1 DGND AGND AISENSE AIGND ACH6 ACH4 ACH2 ACH0 DGND OUTB2 GATB1 EXTCONV EXTTRIG PC6 PC4 CLKB2 GATB0 PC2 PC0 PB6 PB4 PB2 PB0 PA6 PA4 PA2 PA0 DAC1OUT DAC0OUT...

Страница 27: ...for analog output channel 1 13 DGND N A N A Digital Ground Voltage ground reference for the digital signals and the 5 V supply 14 21 PA 0 7 DIO DGND Port A 0 through 7 Bidirectional data lines for po...

Страница 28: ...aximum input voltage rating of 35 V powered on and 25 V powered off is not exceeded The DAQCard 1200 is guaranteed to withstand inputs up to the maximum input voltage rating Caution Exceeding the inpu...

Страница 29: ...se the instrumentation amplifier in different ways Figure 3 2 shows a diagram of the DAQCard 1200 instrumentation amplifier Figure 3 2 DAQCard 1200 Instrumentation Amplifier Table 3 2 Bipolar and Unip...

Страница 30: ...e input mode of the DAQCard 1200 and making signal connections you must first determine whether the signal source is floating or ground referenced This section describes these two types of signals Flo...

Страница 31: ...lowing sections discuss the use of single ended and differential measurements and give considerations for measuring both floating and ground referenced signal sources Table 3 3 summarizes the recommen...

Страница 32: ...leads travel through noisy environments Differential signal connections reduce noise pickup noise and increase common mode noise rejection With these connections input signals can float within the co...

Страница 33: ...resulting in uncontrollable drift and possible saturation in the amplifier A resistor from each input to ground as shown in Figure 3 3 provides bias current return paths for an AC coupled input signal...

Страница 34: ...or configuration instructions Figure 3 4 Differential Input Connections for Grounded Signal Sources With this connection type the instrumentation amplifier rejects both the common mode noise in the si...

Страница 35: ...signals share a common reference signal at the source If any of the preceding criteria are not met you should use DIFF input mode You can configure the DAQCard 1200 using software for two different t...

Страница 36: ...nal to the AISENSE AIGND pin Any potential difference between the DAQCard 1200 ground and the signal ground appears as a common mode signal at both the positive and negative inputs of the instrumentat...

Страница 37: ...eject common mode noise pickup in the leads connecting the signal sources to the DAQCard 1200 The common mode input range of the DAQCard 1200 instrumentation amplifier is the magnitude of the greatest...

Страница 38: ...is the voltage output signal for AO channel 1 AGND is the ground reference point for both AO channels and analog input The following output ranges are available and for each output range the maximum l...

Страница 39: ...pins DIO on the DAQCard 1200 uses the 82C55A integrated circuit The 82C55A is a general purpose peripheral interface containing 24 programmable I O pins These pins represent the three 8 bit ports PA...

Страница 40: ...s and sensing external device states such as the switch in Figure 3 8 Digital output applications include sending TTL signals and driving external devices such as the LED shown in Figure 3 8 Note The...

Страница 41: ...rent documentation sources The 82C55A terminology refers to the different 82C55A configurations as modes whereas NI DAQ and LabVIEW documentation refers to them as handshaking and no handshaking These...

Страница 42: ...line indicates that the data written from the specified port has been accepted This signal is primarily a response from the external device that it has received the data from the DAQCard 1200 OBF Out...

Страница 43: ...or an input transfer in mode 1 Figure 3 9 Mode 1 Timing Specifications for Input Transfers Name Description Minimum Maximum T1 STB pulse width 100 T2 STB 0 to IBF 1 150 T3 Data before STB 1 20 T4 STB...

Страница 44: ...Specifications for Output Transfers Mode 2 Bidirectional Timing Figure 3 11 shows the timing specifications for bidirectional transfers in mode 2 Name Description Minimum Maximum T1 WRT 0 to INTR 0 2...

Страница 45: ...me Description Minimum Maximum T1 WRT 1 to OBF 0 150 T2 Data before STB 1 20 T3 STB pulse width 100 T4 STB 0 to IBF 1 150 T5 Data after STB 1 50 T6 ACK 0 to OBF 1 150 T7 ACK pulse width 100 T8 ACK 0 t...

Страница 46: ...d to as A0 is a sample interval counter in timed A D conversions The sample interval counter or channel clock controls the time between A D conversions A sample interval is also referred to as the int...

Страница 47: ...the posttrigger mode EXTTRIG serves as an external trigger that initiates a DAQ sequence When you use counter A0 to time sample intervals a rising edge on EXTTRIG starts counter A0 and the DAQ sequenc...

Страница 48: ...The maximum number of samples acquired after the stop trigger is limited to 65 535 The number of samples acquired before the trigger is limited only by the size of the memory buffer available for dat...

Страница 49: ...rnally through OUTB1 and EXTCONV Channels 1 and 0 of the input multiplexers are being scanned once during each scan interval The first rising edge of EXTCONV must occur a minimum of 50 ns after the ri...

Страница 50: ...TE signal or counter A2 is sensed Furthermore an interrupt is generated whenever a rising edge is detected on the EXTUPDATE bit The interrupt service routine can write the next value to the DAC When t...

Страница 51: ...configure the DACs in a combination of modes doing so can result in glitches on the immediate update DAC if the update rate on the waveform DAC is high Refer to the Analog Output section in Chapter 4...

Страница 52: ...cations for signal voltage and current specifications You perform pulse and square wave generation by programming a counter to generate a timing signal at its OUT output pin Perform event counting by...

Страница 53: ...time lapse since receiving the edge equals the counter value difference loaded value minus read value multiplied by the CLK period To perform frequency measurement program a counter to be level gated...

Страница 54: ...re 3 19 Frequency Measurement Application Figure 3 20 shows the timing requirements for the GATE and CLK input signals and the timing specifications for the OUT output signals of the 82C53 Signal Sour...

Страница 55: ...ed to 1 A Caution Do not directly connect this 5 V power pin to analog or digital ground or to any other voltage source on the DAQCard 1200 or any other device Doing so can damage the DAQCard 1200 or...

Страница 56: ...able fuse which has an internal thermostat This thermostat opens when the current exceeds 1 A and the temperature rises After some time the thermostat cools down the switch closes and the 5 V is avail...

Страница 57: ...f the DAQCard 1200 Figure 4 1 DAQCard 1200 Block Diagram I O Connector 5 V PCMCIA I O Channel Interface Decode Circuitry Core Logic 4 4 8 8 8 1 1 8 8 8 8 3 Interrupt Interface 82C53 Ctr Timer Group A...

Страница 58: ...peration of each of the DAQCard 1200 components PC Card I O Channel Interface Circuitry The DAQCard 1200 PC Card I O channel interface circuitry is shown in Figure 4 2 and consists of an address bus a...

Страница 59: ...the system has assigned the card to a section of memory it updates the PC Card control registers and initializes the card The rest of the circuitry consists of address decoders data buffers I O chann...

Страница 60: ...DATE I O Connector General Purpose Counter GATEB2 CLKB2 OUTB2 Scan Interval General Purpose Counter GATEB1 CLKB1 OUTB1 MUX CLKA0 Timebase Extension General Purpose Counter OUTB0 GATEB0 CLKB0 2 MHz Sou...

Страница 61: ...Group B and includes B0 B1 and B2 You can use counters B0 and B1 for internal DAQ and DAC timing or you can use the external timing signal CLKB1 for AI timing If you are not using Counters B0 and B1 f...

Страница 62: ...nel data acquisition you select the channel and gain before initiating data acquisition These gain and multiplexer settings remain constant during the entire DAQ process For multiple channel data acqu...

Страница 63: ...forcing quantization noise to become a zero mean random variable rather than a deterministic function of input The DAQCard 1200 uses a 12 bit successive approximation ADC The 12 bit resolution of the...

Страница 64: ...her internally by counter A1 of the 82C53A counter timer circuitry which counts the total number of samples taken during a finite operation or through software control in a continuous operation Round...

Страница 65: ...12 bit accuracy before you perform an A D conversion or 12 bit accuracy is not achieved The settling time is a function of the selected gain Table 4 1 shows the recommended settling time for each gai...

Страница 66: ...igure 4 5 shows the AO circuitry Figure 4 5 Analog Output Circuitry Analog Output Circuitry Each AO channel contains a 12 bit DAC The DAC in each AO channel generates a voltage proportional to the 5 V...

Страница 67: ...update the DAC voltages In the first mode the DAC output voltage is updated as soon as you write to the corresponding DAC This mode is called the immediate update mode In the second mode the DAC outp...

Страница 68: ...the DAQCard 1200 I O connector Figure 4 6 shows the DIO circuitry Figure 4 6 Digital I O Circuitry All three ports on the 82C55A are TTL compatible When enabled the digital output ports are capable of...

Страница 69: ...tion Constants The DAQCard 1200 device is factory calibrated at approximately 25 C to the levels indicated in Appendix A Specifications The associated calibration constants the values that were writte...

Страница 70: ...y external calibration If you are interested primarily in relative measurements you can ignore a small amount of gain error and self calibration should be sufficient External Calibration The DAQCard 1...

Страница 71: ...f channels 8 single ended 8 pseudodifferential or 4 differential software selectable Resolution 12 bits 1 in 4 096 Max single channel sampling rate 100 kS s Input signal ranges Input coupling DC Type...

Страница 72: ...racy 0 5 LSB typ dithered 1 5 LSB max undithered DNL 1 LSB max No missing codes 12 bits guaranteed Offset error Pre gain error after calibration 10 V max Pre gain error before calibration 20 mV max Po...

Страница 73: ...mic Characteristics Bandwidth Small signal 3 dB Settling time to full scale step System noise not including quantization error Gain Bandwidth 1 10 250 kHz 20 150 kHz 50 60 kHz 100 30 kHz Gain Accuracy...

Страница 74: ...20 kS s1 Type of DAC Double buffered Data transfers Interrupts programmed I O Transfer Characteristics Relative accuracy INL 0 5 LSB typ 1 LSB max DNL 0 5 LSB typ 0 9 LSB max Monotonicity 12 bits gua...

Страница 75: ...mA momentary short circuit protection to ground Power on state 0 to 110 ms 2 V to 5 V 110 ms 0 V mV Dynamic Characteristics Settling time to full scale step 20 s to 1 LSB accuracy Noise 400 Vrms typ D...

Страница 76: ...Number of channels 3 counters timers Digital logic levels Level Min Max Input low voltage 0 3 V 0 8 V Input high voltage 2 2 V 5 3 V Output low voltage Iout 2 5 mA 0 4 V Output high voltage Iout 40 A...

Страница 77: ...ax Max source frequency 8 MHz Min source pulse duration 125 ns Min gate pulse duration 100 s Data transfers Interrupts programmed I O Digital Trigger Compatibility TTL Response Rising edge Pulse width...

Страница 78: ...ets the requirements of the following standards for safety and electrical equipment for measurement control and laboratory use EN 61010 1 1993 A2 1995 IEC 61010 1 1990 A2 1995 UL 3111 1 1994 CAN CSA c...

Страница 79: ...n the DoC for this product click Declaration of Conformity at ni com hardref nsf This web site lists the DoCs by product family Select the appropriate product family followed by your product and a lin...

Страница 80: ...on The DAQPad 1200 is a DAQ device that plugs into the parallel port of the computer It is functionally identical to the Lab PC In addition there are no jumpers for bus resource allocation this is don...

Страница 81: ...nnot use DMA Waveform generation Can do waveform generation on one DAC and immediateupdates on the other DAC Can do waveform generation on one DAC and immediate updates on the other Should do either i...

Страница 82: ...version 6 6 x or version 4 9 4 or earlier What is the best way to test the DAQCard without having to program the DAQCard If you are using Windows MAX has a Test Panel option that is available by click...

Страница 83: ...mplete list of functions supported by the DAQCard 1200 If you are using NI DAQ 6 6 or earlier refer to Appendix C NI DAQ Function Support of the NI DAQ Function Reference Manual for PC Compatibles I w...

Страница 84: ...the latest example programs system configurators tutorials technical news as well as a community of developers ready to share their own techniques Customer Education NI provides a number of alternati...

Страница 85: ...sites from the Worldwide Offices section of ni com Branch office Web sites provide up to date contact information support phone numbers e mail addresses and current events If you have searched the tec...

Страница 86: ...106 G giga 109 t tera 1012 Numbers Symbols degrees ohms percent A A amperes A D analog to digital AC alternating current ACH analog input channel signal ACK Acknowledge Input A low signal on this han...

Страница 87: ...nalog input AIGND analog input ground signal AISENSE analog input sense signal AO analog output AWG American Wire Gauge B BCD binary coded decimal bipolar a signal range that includes both positive an...

Страница 88: ...and possibly generating control signals with D A and or DIO devices in the same computer DATA Data Lines at the Specified Port the signal that indicates when teh data on the data lines at a specified...

Страница 89: ...is the first data sent to the acceptor FIFOs are often used on DAQ devices to temporarily store incoming or outgoing data until that data can be retrieved or output For example an analog input FIFO st...

Страница 90: ...ations channels operator interface devices and or data acquisition and control interfaces IBF Input Buffer Full A high signal on this handshaking line indicates that data has been loaded into the inpu...

Страница 91: ...nt bit N NC not connected signal NI National Instruments NI DAQ National Instruments driver software for DAQ hardware NRSE nonreferenced single ended mode all measurements are made with respect to a c...

Страница 92: ...humidity RMA Return Material Authorization rms root mean square RSE referenced single ended mode input mode where the negative input of the instrumentation amplifier is referenced to AISENSE AIGND whi...

Страница 93: ...nt VCC positive supply voltage from the PCMCIA bus usually 5V VDC volts direct current VI virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the...

Страница 94: ...timing continuous data acquisition 4 8 data acquisition operation 4 8 interval data acquisition 4 8 polarity configuration 2 4 settings table 2 3 specifications amplifier characteristics A 2 dynamic...

Страница 95: ...haracteristics A 4 voltage output A 5 theory of operation 4 10 B bus interface specifications A 7 C calibration EEPROM storage 5 1 loading calibration constants 5 1 overview 5 1 CLK signals general pu...

Страница 96: ...ersus gain table 4 9 data acquisition timing circuitry continuous data acquisition 4 8 data acquisition operation 4 8 interval data acquisition 4 8 data acquisition timing connections See also general...

Страница 97: ...purpose timing signal connections 3 29 frequently asked questions E 1 G GATB0 signal table 3 3 GATB1 signal table 3 4 GATB2 signal table 3 4 GATE signals general purpose timing signal connections 3 2...

Страница 98: ...ide offices E 2 National Instruments documentation xii NI Developer Zone E 1 NI DAQ driver software 1 2 NRSE input configuration 2 5 definition table 2 4 recommended input configurations table 3 7 sin...

Страница 99: ...ipolar and unipolar signal range versus gain table 3 5 common mode signal rejection 3 13 differential connections floating signal sources 3 8 grounded signal sources 3 10 single ended connections 3 11...

Страница 100: ...are wave generation 3 28 stability analog input specifications A 4 analog output specifications A 5 STB signal table 3 18 system integration by National Instruments E 1 T technical support resources E...

Страница 101: ...x DAQCard 1200 User Manual I 8 ni com U unpacking the DAQCard 1200 1 5 V voltage output specifications A 5 W Web support from National Instruments E 1 worldwide technical support E 2 WRT signal table...

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