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NI 5112 User Manual

1. Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply This font is used for the proper names of disk drives paths directories programs subprograms subroutines device names filenames and extensions and code excerpts Contents Chapter 1 Taking Measurements with the NI 5112 Installing the Software and Hardware 00 cceeeesceseeseeseeeeeeseceeeeseeseeeeecaeeesesseensesseenaes 1 1 Co necting Signals 2c32e estes eves ted aac eee GA eda es ag ec 1 1 Acquiring Data with Your NI 5112 oe cece eeceeseseeeeseeseeeseseeeaeceeeaesneeeaeeneeaes 1 3 Programmatically Controlling Your NI 5112 0 eee eeeeseeeeeeeeeseeeees 1 3 Interactively Controlling Your NI 5112 with VirtualBench Scope 1 3 ACQUITING Data sais cies ccesesetid ehensueed deveeseeeaiv ens cis wosnaen thers EENS 1 4 Soft Front Panel Features 200 pinse e e e Rs 1 6 Safety INLOrmatwon syi 32h c cess Sees vag r a dese A ated tea coh E E Gomes cleans 1 7 Chapter 2 Hardware Overview Measurement Fundamentals ssiri kevren e a e T 2 2 Taput Ranges rerea oaea aE E EEE a EERE E E E NA 2 2 Input Impedance srei asri E E E EE E R 2 2 AC Couplings oeeo iis nie wile E andes E A ARS 2 3 DG Offset sets etic iinet deci aikies Nis Gudiia teehee tiisaee 2 4 20 MHz Bandwidth Limit 0 eee ngn 2 5 External Tr Ogres ssesccoics
2. D dB DC default setting device differential input double insulated drivers E EEPROM equivalent time sampling event National Instruments Corporation G 3 Glossary common mode rejection ratio a measure of an instrument s ability to reject interference from a common mode signal usually expressed in decibels dB a circuit that counts external pulses or clock pulses timing the manner in which a signal is connected from one location to another decibel the unit for expressing a logarithmic measure of the ratio of two signal levels dB 20log10 V1 V2 for signals in volts direct current a default parameter value recorded in the driver In many cases the default input of a control is a certain value often 0 that means use the current default setting a plug in data acquisition board card or pad The NI 5112 is an example of a device an analog input consisting of two terminals both of which are isolated from computer ground whose difference is measured a device that contains the necessary insulating structures to provide electric shock protection without the requirement of a safety ground connection software that controls a specific hardware instrument electrically erasable programmable read only memory ROM that can be erased with an electrical signal and reprogrammed any method used to sample signals in such a way that the apparent sampling rate is higher than the real sampl
3. The following figure shows the VirtualBench Scope soft front panel gt VirtualBench Scope Scope File Edit Controls Measure Help Channels mm Chi Math 1 Volts div Ref mj Ref2 a SA Coupling DC J Timebase V Position 3 p Alan 3 Slope s Run wj Single ae cae Via Mode eA Select Ea 4 H Set 50 m 1 Channel Selector 4 Vertical Slider 6 Zoom Controls 2 Channel Settings Group 5 Main Control Bar 7 Graphics Display Trigger Settings Group Figure 1 4 VirtualBench Scope Soft Front Panel The VirtualBench Scope soft front panel has the following features e Channel selector picks channels or math functions that display waveforms e Channel settings group NI 5112 User Manual Channel settings selector selects the channel whose settings will be modified Coupling toggles between DC and AC coupling Volts div adjusts the vertical resolution of the channel you select V Position controls the displayed voltage offset 1 6 ni com Chapter 1 Taking Measurements with the NI 5112 e Trigger settings group controls the conditions required for signal acquisition For example you can command VirtualBench Scope to wait for a digital trigger or command it to acquire data without triggering in free run mode e Vertical Slider adjusts the voltage offset for each channel Use this slider to adjust multiple waveforms e Main control bar buttons Runac
4. an SMB connector and a 9 pin miniature circular DIN connector Two of the BNC connectors CHO and CH1 are for attaching the analog input signals you wish to measure The third BNC connector TRIG is for the analog trigger channel The SMB connector PFI is for external digital triggers and for generating a probe compensation signal The DIN connector AUX gives you access to an additional external digital trigger line PFI2 National Instruments Corporation 1 1 NI 5112 User Manual Chapter 1 Taking Measurements with the NI 5112 INSTRUMENTS Figure 1 1 NI 5112 Connectors QO OO 00 1 5 Volts Fused 4 Reserved 7 Reserved 2 GND 5 Reserved 8 Reserved 3 Reserved 6 PFI2 9 Reserved Figure 1 2 9 Pin Mini Circular DIN Connector NI 5112 User Manual 1 2 ni com Chapter 1 Taking Measurements with the NI 5112 Acquiring Data with Your NI 5112 You can acquire data either programmatically by writing an application for your NI 5112 or interactively with the VirtualBench Scope soft front panel Programmatically Controlling Your NI 5112 To help you get started programming your NI 5112 NI SCOPE comes with examples that you can use or modify You can find examples for these different ADEs e LabVIEW Go to Program Files National Instruments LabVIEW Examples Instr niScopeExamples 11b e CVI C and Visual Basic with Windows
5. 100 MS n where n is a number from 1 to 100e 6 RIS can be used on repetitive signals to effectively extend the sampling rate above 100 MS s In RIS mode you can sample at rates of 100 MS s x n where n is a number from 2 to 25 During the acquisition samples are stored in a circular buffer that is continually rewritten until a trigger is received After the trigger is received the NI 5112 continues to acquire posttrigger samples if you have specified a posttrigger sample count The acquired samples are placed into onboard memory The number of posttrigger or pretrigger samples is limited only by the amount of onboard memory Regardless of the user requested sample rate the NI 5112 ADC is always running at 100 MS s The NI 5112 stores a stream of 8 bit samples into the onboard memory at the requested sample rate If you request a rate less than 100 MS s the timing engine of the NI 5112 only stores 1 sample in a group of n samples effectively reducing the sample rate to 100 MS n National Instruments Corporation 2 5 NI 5112 User Manual Chapter 2 Hardware Overview Calibration The NI 5112 can calibrate numerous device parameters due to an advanced calibration scheme There are two different calibration schemes depending on the type of calibration to be performed Internal calibration the more common of the two schemes is performed via a software command that compensates for drifts caused by environmental temperature changes Inte
6. 3 sampling methods random interleaved RIS 2 5 real time 2 5 signal shape general B 9 SMB connector 1 1 to 1 2 soft front panel See VirtualBench Scope soft front panel software installation 1 1 source impedance B 8 specifications acquisition modes A 3 acquisition system A 1 to A 2 calibration A 5 certifications and compliances A 4 I O connectors A 4 operating environment A 4 physical A 3 power requirements A 3 storage environment A 4 timebase system A 2 triggering system A 2 to A 3 NI 5112 User Manual Index Star Trigger PXI devices 2 12 storage environment specifications A 4 synchronizing multiple devices 2 12 to 2 13 PCI devices 2 12 PFI lines and synchronization 2 13 PXI devices 2 11 to 2 12 specifications for timebase system A 2 system integration by National Instruments C 1 System Reference Clock PXI devices 2 11 T TCD time to digital converter B 6 technical support resources C 1 to C 2 timebase system specifications A 2 time to digital converter TDC B 6 trigger external 2 5 Trigger Bus PXI devices 2 12 Trigger Output signal 2 13 triggering and arming 2 7 to 2 10 analog trigger circuit 2 8 to 2 9 falling edge analog trigger 2 9 high hysteresis analog triggering mode 2 8 low hysteresis analog triggering mode 2 9 rising edge analog trigger 2 9 NI 5112 User Manual l 4 digitizer options B 5 specifications A 2 to A 3 trigger hold off 2 9 to 2 10 B
7. 9 trigger sources figure 2 7 V vertical sensitivity B 3 to B 4 VirtualBench Scope soft front panel acquiring data 1 4 to 1 5 features 1 6 to 1 7 launching 1 3 W Web support from National Instruments C 1 Worldwide technical support C 2 ni com
8. A Specifications for input limits that must be observed regardless of coupling NI 5112 User Manual B 10 ni com Technical Support Resources Web Support National Instruments Web support is your first stop for help in solving installation configuration and application problems and questions Online problem solving and diagnostic resources include frequently asked questions knowledge bases product specific troubleshooting wizards manuals drivers software updates and more Web support is available through the Technical Support section of ni com NI Developer Zone The NI Developer Zone at ni com zone is the essential resource for building measurement and automation systems At the NI Developer Zone you can easily access the latest example programs system configurators tutorials technical news as well as a community of developers ready to share their own techniques Customer Education National Instruments provides a number of alternatives to satisfy your training needs from self paced tutorials videos and interactive CDs to instructor led hands on courses at locations around the world Visit the Customer Education section of ni com for online course schedules syllabi training centers and class registration System Integration If you have time constraints limited in house technical resources or other dilemmas you may prefer to employ consulting or system integration services You can rely on th
9. alias amplification amplitude flatness attenuate bandwidth buffer bus clock NI 5112 User Manual analog to digital analog to digital converter an electronic device often an integrated circuit that converts an analog voltage to a digital number the resolution of the ADC which is measured in bits An ADC with16 bits has a higher resolution and thus a higher degree of accuracy than a 12 bit ADC a false lower frequency component that appears in sampled data acquired at too low a sampling rate a type of signal conditioning that improves accuracy in the resulting digitized signal and reduces noise a measure of how close to constant the gain of a circuit remains over a range of frequencies to reduce in magnitude bit one binary digit either 0 or 1 byte eight related bits of data an eight bit binary number Also used to denote the amount of memory required to store one byte of data the range of frequencies present in a signal or the range of frequencies to which a measuring device can respond temporary storage for acquired or generated data software the group of conductors that interconnect individual circuitry in a computer Typically a bus is the expansion vehicle to which I O or other devices are connected Examples of PC buses are the PCI and ISA bus Celsius hardware component that controls timing for reading from or writing to groups G 2 ni com CMRR counter timer coupling
10. sampling methods 2 5 specifications A 1 to A 2 ADC resolution B 4 analog bandwidth B 2 analog trigger circuit 2 8 to 2 9 falling edge analog trigger 2 9 high hysteresis analog triggering mode 2 8 low hysteresis analog triggering mode 2 9 rising edge analog trigger 2 9 arming See triggering and arming bandwidth 20 MHz bandwidth limit 2 4 analog bandwidth B 2 National Instruments Corporation block diagram of NI 5112 2 1 BNC connectors 1 1 to 1 2 C calibration 2 6 to 2 7 external 2 7 internal 2 6 to 2 7 specifications A 5 certifications and compliances A 4 connectors BNC connectors 1 1 to 1 2 DIN connector 1 1 to 1 2 SMB connector 1 1 to 1 2 specifications A 4 conventions used in manual vi customer education C 1 D data acquisition See acquiring data DC offset 2 4 dead time in multiple record acquisitions 2 10 digitizers B 1 to B 10 accurate measurements B 7 to B 10 input coupling B 10 source impedance B 8 ADC resolution B 4 analog bandwidth B 2 Nyquist theorem B 1 random interleaved sampling B 5 to B 7 record length B 4 sample rate B 2 to B 3 settings for accurate measurements general signal shape B 9 input frequency B 9 NI 5112 User Manual Index peak to peak value B 7 to B 8 triggering options B 5 vertical sensitivity B 3 to B 4 DIN connector 1 1 to 1 2 E Equivalent Time Sampling ETS B 5 external calibration 2 7 external trigger 2 5 F
11. the equipment is turned off Before you remove the device disconnect the AC power line or any high voltage sources 30 Vims and 42 4 Vpeax or 60 VDC that may be connected to the device National Instruments Corporation 1 7 NI 5112 User Manual Chapter 1 Taking Measurements with the NI 5112 Do not operate the device in an explosive atmosphere or where there may be flammable gases or fumes To ensure adequate grounding the device must be properly installed in the chassis National Instruments is not liable for any damages or injuries resulting from inadequate safety earth ground connections You must insulate all of your signal connections to the highest voltage with which the NI 5112 may come in contact Equipment described in this document must be used in an Installation Category II or lower environment per IEC 61010 1 and UL 3111 1 Do not operate damaged equipment The safety protection features built into this device can be impaired if the device becomes damaged in any way If it is damaged turn the device off and do not use it until service trained personnel can check its safety If necessary return the device to National Instruments for service and repair to ensure that its safety is not compromised Clean the device and accessories by brushing off light dust with a soft non metallic brush Remove other contaminants with a stiff non metallic brush The unit must be completely dry and free from contaminants before returnin
12. traceable onboard reference for the calibration Internal calibration performs the following operations e Gain and offset are calibrated for each individual input range e AC flatness is calibrated over the entire bandwidth to be within specified tolerances 2 6 ni com e Analog trigger levels are calibrated Chapter 2 Hardware Overview e The time to digital converter used for RIS measurements is calibrated External Calibration External calibration adjusts the internal reference on the NI 5112 Although the NI 5112 is factory calibrated it needs periodic external calibration to verify that it is still within the specified accuracy For more information on calibration contact National Instruments or visit the National Instruments Web site at ni com calibration Triggering and Arming There are several triggering methods for the NI 5112 The trigger can be an analog level that is compared to the input or any of several digital inputs You can also call a software function to trigger the device Figure 2 4 shows the different trigger sources The digital triggers are TTL level signals with a minimum pulse width requirement of 10 ns COMP Low __ COMP am Analog Trigger ATC_OUT Circuit Level a Analog Trigger Circuit Software _____ ATC_OUT i RTSI lt 0 6 gt 7 PFI1 PFI2 1 b Trigger Sources Trigger Figure 2 4 Trigger Sources National Instr
13. 171 79 s gt 1000 steps in full scale voltage range 2 5 of range setting 0 5 of offset setting 500 mV 100 MHz 10 V 1 MQ II 30 pF or 50 Q software selectable 42 V DC peak AC 200 MS s to 2 5 GS s effective sample rate for repetitive signals only 1 S s to 100 MS s sample rate for transient and repetitive signals 0 5 A 1 5A 10 by 16 cm 4 2 by 6 87 in NI 5112 User Manual Appendix A Specifications 1 0 Connectors Analog inputs CHO CH1 ee BNC female Analog trigger TRIG neess BNC female Digital trigger PHIL oo eee SMB female Digital trigger PFI2 00 ee 9 pin DIN Operating Environment Ambient temperature eee 0 to 40 C Relative humidity eee 10 to 90 noncondensing Storage Environment Safety Ambient temperature 0 0 0 eee ee 20 to 70 C Relative humidity o oo 5 to 95 noncondensing Designed in accordance with IEC 61010 1 UL 3111 1 and CAN CSA C22 2 no 1010 1 for electrical measuring and test equipment Approved for altitudes up to 2000 m Installation Category II Pollution Degree 2 Indoor use only Certifications and Compliances NI 5112 User Manual CE Mark Compliance A 4 ni com Appendix A Specifications Calibration Internal annt n dose a eee eeb ees Internal calibration is done on software command The calibration involves gain offset frequency response and timing adjustment for all input ranges Int rvall2 2 050 8
14. 98 95 Go to vxipnp win95 Niscope Examples e CVI C and Visual Basic with Windows 2000 NT Go to vxipnp winnt Niscope Examples Other resources include the NI SCOPE Instrument Driver Quick Reference Guide It contains abbreviated information on the most commonly used functions and LabVIEW VIs For more detailed function reference help see the NI SCOPE Function Reference Help file located at Start Programs National Instruments SCOPE For more detailed VI help use LabVIEW context sensitive help Help Show Context Help Interactively Controlling Your NI 5112 with VirtualBench Scope Use the VirtualBench Scope soft front panel to interactively control your NI 5112 as you would a desktop oscilloscope The following sections explain how to make connections to your NI 5112 and take simple measurements using the VirtualBench Scope soft front panel as shown in Figure 1 3 later in this chapter To launch the soft front panel select Start Programs National Instruments SCOPE VirtualBench Scope National Instruments Corporation 1 3 NI 5112 User Manual Chapter 1 Taking Measurements with the NI 5112 Acquiring Data When you launch VirtualBench Scope it operates in continuous run mode To start acquiring signals with VirtualBench Scope complete the following steps 1 Connect a signal to channel 0 and or channel 1 of your NI 5112 2 Configure VirtualBench Scope a From the Edit menu on the front panel select General Setti
15. ADC Signal A Variable Ch 11 agu C Gain and Attenuation Selectable 50 Q i Termination Offset Adjustment 100 MHz Calibration gt Signal Trigger Trigger Timing Trigger Mux Generation Control Channel Input Selectable 509 Termination V Figure 2 1 NI 5112 Block Diagram National Instruments Corporation 2 1 NI 5112 User Manual Chapter 2 Hardware Overview Measurement Fundamentals Input Ranges Input Impedance NI 5112 User Manual The NI 5112 has a programmable gain amplifier PGA at the analog input The purpose of the PGA is to accurately interface to and scale the signal presented at the connector for the analog to digital converter ADC regardless of source impedance source amplitude or DC biasing To optimize the ADC resolution you can select different gains for the PGA In this way you can scale your input signal to match the full input range of the converter The NI 5112 PGA offers a variable input range from 0 025 V to 25 V These input ranges are available in 10 steps For example some typical ranges are 48 5 mV 53 3 mV 58 7 mV 64 6 mV 71 0 mV 78 1 mV 86 1 mV and so on Notice that each range is 10 higher than the one before it The second value 53 3 is found by adding 10 to the first value 48 5 4 85 Since the ranges are calibrated on a per device basis the ranges of your device may be slightly different than the ones listed here When you request a range the driver softwa
16. Bit ADC with Three Different Gain Settings and a 600 mV Peak to Peak Input Signal e Source impedance Most digitizers and digital storage oscilloscopes DSOs have a 1 MQ input resistance in the passband If the source impedance is large the signal will be attenuated at the amplifier input and the measurement will be inaccurate If the source impedance is unknown but suspected to be high change the attenuation ratio on your probe and acquire data In addition to the input resistance all digitizers DSOs and probes present some input capacitance in parallel with the resistance This capacitance can interfere with your measurement in much the same way as the resistance does NI 5112 User Manual B 8 ni com Appendix B Digitizer Basics Input frequency If your sample rate is less than twice the highest frequency component at the input the frequency components above half your sample rate will alias in the passband at lower frequencies indistinguishable from other frequencies in the passband If the signal s highest frequency is unknown you should start with the digitizer s maximum sample rate to prevent aliasing and reduce the digitizer s sample rate until the display shows either enough cycles of the waveform or the information you need General signal shape Some signals are easy to capture by ordinary triggering methods A few iterations on the trigger level finally render a steady display This method works for sinusoidal triang
17. Computer Based Instruments NI 5112 User Manual SinstruMeNts A hese Worldwide Technical Support and Product Information ni com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 794 0100 Worldwide Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Ottawa 613 233 5949 Canada Qu bec 514 694 8521 China Shanghai 021 6555 7838 China ShenZhen 0755 3904939 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 5 280 7625 Netherlands 0348 433466 New Zealand 09 914 0488 Norway 32 27 73 00 Poland 0 22 528 94 06 Portugal 351 1 726 9011 Singapore 2265886 Spain 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2528 7227 United Kingdom 01635 523545 For further support information see the Technical Support Resources appendix To comment on the documentation send e mail to techpubs ni com Copyright 1999 2001 National Instruments Corporation All rights reserved Important Information Warranty The NI 5112 is 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 Nationa
18. Figure 2 6 Low Hysteresis Analog Triggering Mode Rising Edge Analog Trigger Rising edge analog trigger mode is the same as high hysteresis analog trigger mode except that the hysteresis value used is automatically set to 2 5 of the range of the chosen trigger source Falling Edge Analog Trigger Falling edge analog trigger mode is the same as low hysteresis analog trigger mode except that the hysteresis value used is automatically set to 2 5 of the range of the chosen trigger source Trigger Hold Off The trigger hold off is a length of time that the NI 5112 waits after a trigger is accepted before the next acquisition starts In other words when a trigger is received during an acquisition the trigger counter is loaded with the desired hold off time Hardware is not rearmed until the counter has expired or the current acquisition completes whichever is longer The time the acquisition takes to complete from the time a trigger occurs is determined by the following equation acquisition completion time a If this time is larger than the trigger hold off time the trigger hold off has no effect because triggers are always rejected during acquisition Trigger hold off is provided in hardware using a 32 bit counter clocked by a 25 MHz internal timebase With this configuration you can select a hardware hold off value of 100 us to 171 79 s in increments of 40 ns National Instruments Corporation 2 9 NI 5112 User Manual Chapte
19. NANTICIPATED USES OR MISUSES OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED SYSTEM FAILURES ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE TO AVOID DAMAGE INJURY OR DEATH THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES INCLUDING BUT NOT LIMITED TO BACK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION Compliance FCC Canada Radio Frequency Interference Compliance Determining FCC Class The Federal Communications Commission FCC has rules to protect wireless communications from interference The FCC places digital electronics into two cla
20. TTL signal that pulses to a high level for at least 40 ns after the board triggers National Instruments Corporation 2 13 NI 5112 User Manual Specifications This appendix lists the specifications of the NI 5112 These specifications are typical at 25 C unless otherwise specified Acquisition System ReSOLUtION 000 cccccecceeeeeeeeesesesereeeees Bandwidth 3 dB Number of channels Maximum sample rate eeeeeeeeeees Onboard sample memory Calibrated vertical ranges Calibrated offset ranges 0 0 0 100 MHz maximum 20 MHz typical with bandwidth limit enabled 2 simultaneously sampled single ended 2 5 GS s repetitive 100 MS s single shot 16 or 32 MB per channel depending on memory option purchased 25 mV to 25 V in 10 steps 500 mV for vertical ranges smaller than 500 mV 5 V for vertical ranges between 500 mV and 5 V 50 V for vertical ranges greater than 5 V DG accuracy ie priri 2 5 of range setting Input Coupling sessen enn AC coupling cutoff frequency 3 dB sesers National Instruments Corporation A 1 0 5 of offset setting DC or AC software selectable 11 Hz with 1x probe 1 1 Hz with 10x probe NI 5112 User Manual Appendix A Specifications Timebase System Triggering System NI 5112 User Manual Input impedance Input protection eee eeeeeeereee Number of timebases Clock accuracy as master Clock input tolerance as slave C
21. aeseeeesesseeeaeeseees 2 11 Synchronizing Multiple PXI Devices 0 e eee eceeeeseeseeeeeeeeeeeteeneeeseeenees 2 11 Synchronizing Multiple PCI Devices 0 eee eee eeeeeeseceeeeeeeeesaeeeneeseeeees 2 12 PFI Lines and Synchronization eee eee eeeeeeeeeeeeeeseeseeesecseeesesseeesessenaes 2 13 PFI Limes aS Inputs ronne ittee hens al teehee ee 2 13 PFI Lines as Outputs ies esses ies asses dese ste raapia anassa EAEE SERRER SES PEGER 2 13 Appendix A Specifications Appendix B Digitizer Basics Appendix C Technical Support Resources Glossary Index NI 5112 User Manual viii ni com Taking Measurements with the NI 5112 Thank you for buying a National Instruments 5112 digital oscilloscope This chapter provides information on installing connecting signals to and acquiring data from the NI 5112 Installing the Software and Hardware There are two main steps involved in installation 1 Install the NI SCOPE driver software You use this driver to write programs to control your NI 5112 in different application development environments ADEs NI SCOPE also allows you to interactively control your NI 5112 with VirtualBench Scope 2 Install your NI 5112 For step by step instructions for installing NI SCOPE and the NI 5112 see the Where to Start with Your National Instruments Oscilloscope Digitizer Connecting Signals Figure 1 1 shows the front panel for the NI 5112 which contains five connectors three BNC connectors
22. all the requested records have been stored in memory After the initial setup this process does not require software intervention Between each record there is a dead time of approximately 500 ns during which no triggers are accepted During this time the memory controller sets up for the next record There is also a hold off of 100 us from the last 2 10 ni com Chapter 2 Hardware Overview trigger in a record to the start of a new record That means that the actual dead time will be the greater of the between record dead time 500 ns post trigger storage time and the 100 us hold off time There may also be additional dead time while the minimum number of pretrigger samples are being acquired To increase the dead time between records use the trigger hold off feature Figure 2 8 shows a timing diagram of a multiple record acquisition X v X SY x Trigger lt 100 us hold off gt Acquisition lt 500 ns gt In Progress Record 1 X 2 x Trigger Not Accepted Pretrigger Points Not Acquired X Trigger Not Accepted 500 ns Dead Time X Trigger Not Accepted Acquisition in Progress vV Trigger Accepted Figure 2 8 Multiple Record Acquisition Synchronizing Multiple Devices The NI 5112 uses a phase locked loop to synchronize the 100 MHz sample clock to a 10 MHz reference clock This reference frequency can be supplied by a crystal oscillator on the device or through an external fre
23. and improve the accuracy of the measurement You can apply up to 50 V of DC offset to the NI 5112 input stage a 1 25 V F WV IIIS 4 h V 4 V T 0 75 V 7 Offset 0 V Offset 1 V Range 2 5 V Range 0 5 V ion 2 0V ion 0 5V Resolution 256 10 mV Resolution 256 2 mV Figure 2 3 DC Offset Table 2 1 lists the maximum DC offset for a given input voltage range Table 2 1 Maximum DC Offset Vertical Range Maximum Selectable Offset 50 mV 500 mV 500 mV 500 mV 5 V 5 V 5 V 50 V 50 V 2 4 ni com Chapter 2 Hardware Overview 20 MHz Bandwidth Limit External Trigger The NI 5112 has a selectable 20 MHz bandwidth limit on the analog input channels This limit enables a lowpass filter that can remove unwanted noise above 20 MHz from your measurement The NI 5112 external trigger is a front panel BNC input that allows you to connect an analog signal as a trigger without connecting the trigger to one of the input channels This external trigger allows you to use the input channels and external trigger concurrently The input range for the external trigger input is 10 V You can select either AC or DC coupling Acquisition System Acquisition Mode The NI 5112 acquisition system controls the way samples are acquired and stored Two sampling methods are available real time sampling and random interleaved sampling RIS Using real time sampling you can acquire data at a rate of
24. architecture G 4 ni com kS L LabVIEW LSB m MB memory buffer MS MSB noise Nyquist frequency Nyquist Sampling Theorem National Instruments Corporation G 5 Glossary kilo the standard metric prefix for 1 000 or 103 used with units of measure such as volts hertz and meters 1 000 samples laboratory virtual instrument engineering workbench a graphical programming ADE developed by National Instruments least significant bit meters megabytes of memory See buffer million samples most significant bit an undesirable electrical signal 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 a frequency that is one half the sampling rate See Nyquist Sampling Theorem the theorem states that if a continuous bandwidth limited analog signal contains no frequency components higher than half the frequency at which it is sampled then the original signal can be recovered without distortion NI 5112 User Manual Glossary 0 Ohm s Law overrange oversampling P passband PCI peak value PFI posttriggering pretriggering PXI RAM real time sampling NI 5112 User Manual R V I the relatio
25. at the junctions of dissimilar metals that are functions of temperature Also called thermoelectric potentials See thermal EMFs the rate measured in bytes s at which data is moved from source to destination after software initialization and set up operations the maximum rate at which the hardware can operate sampling at a rate lower than the Nyquist frequency can cause aliasing the number of output updates per second volts volts alternating current volts direct current voltage error virtual instrument 1 a combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument 2 a LabVIEW software module VI which consists of a front panel user interface and a block diagram program volts root mean square value the shape the magnitude of a signal creates over time the highest voltage that should be applied to a product in normal use normally well under the breakdown voltage for safety margin G 8 ni com Index Numbers 20 MHz bandwidth limit 2 5 A AC coupling 2 3 AC coupling cutoff frequency 2 3 acquiring data 1 3 to 1 7 interactive control of NI 5112 using VirtualBench Scope 1 3 multiple record acquisitions 2 10 to 2 11 programmatic control of NI 5112 1 3 steps for 1 4 to 1 5 VirtualBench Scope soft front panel features 1 6 to 1 7 acquisition modes overview 2 5 specifications A 3 acquisition system overview 2 5
26. dix B Digitizer Basics Frame 1 Frame 2 Frame 3 Figure B 5 Waveform Reconstruction with RIS The time measurement is made with a time to digital converter TDC The resolution of the TDC is the number of physical bins to which the TDC can quantize the trigger arrival time This resolution should be several times higher than the maximum desired interpolation factor which is the maximum number of logical bins to which you want the trigger arrival time quantized The higher resolution ensures that when the TDC output is requantized to the desired interpolation factor all output values have a roughly equal probability of occurrence that is all logical bins will contain approximately the same number of physical bins NI 5112 User Manual B 6 ni com Appendix B Digitizer Basics For example consider the maximum interpolation factor to be 5 If the TDC could output values from 0 to 15 then each logical bin will contain three physical bins as shown in Figure B 6 Logical Bin gt Sample Clock 3 Physical Bins 1 Logical Bin Physical Bin Desired Interpolation Factor 5 Max Interpolation Factor 15 Figure B 6 Relationship between Interpolation Factor Logical Bins and Physical Bins The maximum interpolation factor on the NI 5112 is 25 resulting in a maximum ETS rate of 2 5 GS s At this rate the ratio of logical bins to physical bins is approximately 1 40 Making Accurate Measurements Fo
27. e expertise available through our worldwide network of Alliance Program members To find out more about our Alliance system integration solutions visit the System Integration section of ni com National Instruments Corporation C 1 NI 5112 User Manual Appendix C Technical Support Resources Worldwide Support National Instruments has offices located around the world to help address your support needs You can access our branch office Web 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 technical support resources on our Web site and still cannot find the answers you need contact your local office or National Instruments corporate Phone numbers for our worldwide offices are listed at the front of this manual NI 5112 User Manual C 2 ni com Glossary Prefix Meanings Value p pico 10 7 n nano 10 9 u micro 10 6 m milli 10 3 k kilo 103 M mega 106 G giga 10 Symbols percent positive of or plus negative of or minus per degree plus or minus Q ohm A amperes AC alternating current AC coupled the passing of a signal through a filter network that removes the DC component of the signal National Instruments Corporation G 1 NI 5112 User Manual Glossary A D ADC ADC resolution
28. er 2 2 ni com memory 2 10 multiple record acquisitions 2 10 to 2 11 NI 5112 See also hardware overview acquiring data interactive control of NI 5112 1 3 programmatic control of NI 5112 1 3 using VirtualBench Scope soft front panel 1 3 to 1 7 block diagram 2 1 connectors 1 1 to 1 2 safety information 1 7 to 1 8 specifications A 1 to A 5 NI Developer Zone C 1 NI SCOPE software 1 1 Nyquist theorem B 1 0 operating environment specifications A 4 P PCI devices synchronizing 2 12 peak to peak value for digitizers dynamic range of 8 bit ADC figure B 8 overview B 7 PFI lines inputs 2 13 outputs 2 13 synchronizing 2 13 PGA programmable gain amplifier 2 2 physical specifications A 3 power requirement specifications A 3 programmable gain amplifier PGA 2 2 programmatic control of NI 5112 1 3 pulse train signal difficult figure B 9 PXI devices synchronizing 2 11 to 2 12 National Instruments Corporation l 3 Index R random interleaved sampling RIS interpolation factor figure B 7 overview 2 5 purpose and use B 5 to B 7 time measurement with time to digital converter B 6 to B 7 waveform reconstruction figure B 6 real time sampling 2 5 record length for digitized samples B 4 Reference Clock signal 2 13 RIS See random interleaved sampling RIS rising edge analog trigger 2 9 S safety information 1 7 to 1 8 safety specifications A 4 sample rate B 2 to B
29. falling edge analog trigger 2 9 Frequency Output signal 2 13 H hardware installation 1 1 hardware overview 2 1 to 2 13 acquisition system 2 5 block diagram 2 1 calibration 2 6 to 2 7 external 2 7 internal 2 6 to 2 7 measurement fundamentals 2 2 to 2 5 20 MHz bandwidth limit 2 5 AC coupling 2 3 DC offset 2 4 external trigger 2 5 input impedance 2 2 to 2 3 input ranges 2 2 memory 2 10 multiple record acquisitions 2 10 to 2 11 synchronizing multiple devices 2 12 to 2 13 PCI devices 2 12 PFI lines and synchronization 2 13 PXI devices 2 11 to 2 12 NI 5112 User Manual l 2 triggering and arming 2 7 to 2 10 analog trigger circuit 2 8 to 2 9 trigger hold off 2 9 to 2 10 high hysteresis analog triggering mode 2 8 impedance input 2 2 to 2 3 source B 8 input coupling B 10 input frequency B 9 input impedance 2 2 to 2 3 input ranges 2 2 installing software and hardware 1 1 interactive control of NI 5112 1 3 internal calibration 2 6 to 2 7 T O connectors See connectors L low hysteresis analog triggering mode 2 9 measurement accuracy for digitizers B 7 to B 10 general signal shape B 9 input coupling B 10 input frequency B 9 peak to peak value B 7 to B 8 source impedance B 8 measurement fundamentals 2 2 to 2 5 20 MHz bandwidth limit 2 5 AC coupling 2 3 DC offset 2 4 external trigger 2 5 input impedance 2 2 to 2 3 input ranges 2 2 PGA programmable gain amplifi
30. g it to service The device must be used in a UL listed chassis Do not substitute parts or modify equipment Because of the danger posed by introducing additional hazards do not install unauthorized parts or modify the device Return the device to National Instruments for service and repair to ensure that its safety features are not compromised Connections including power signals to ground and vice versa that exceed any of the maximum signal ratings on the NI 5112 can damage any or all of the devices in the same chassis National Instruments is not liable for any damages or injuries resulting from incorrect signal connections Use only National Instruments oscilloscope probes or probes bearing the CE mark NI 5112 User Manual 1 8 ni com Hardware Overview This chapter includes an overview of the NI5112 explains the operation of each functional unit making up your NI 5112 and describes the signal connections Figure 2 1 shows a block diagram of the NI 5112 Onboard Calibration gt Calibration Signal Signal Source Calibration Signal kg 8 Variable 8 Bit rona Ce Gainand e lt 100 MS s p Attenuation ADC Selectable 50 Q i Decimation Onboard PCI Termination Memory Interface Offset 8 Adjustment 8 Bit A 100 MS s vA Calibration
31. he NI 5112 also has two digital triggers that give you more flexibility in triggering by allowing you to connect a TTL CMOS digital signal to trigger the acquisition Random Interleaved Sampling Random Interleaved Sampling RIS is a form of Equivalent Time Sampling ETS that allows acquisition of pretriggered data ETS refers to any method used to sample signals in such a way that the apparent sampling rate is higher than the real sampling rate ETS is accomplished by sampling different points along the waveform for each occurrence of the trigger and then reconstructing the waveform from the data acquired over many cycles In RIS the arrival of the waveform trigger point occurs at some time randomly distributed between two sampling instants The time from the trigger to the next sampling instant is measured and this measurement allows the waveform to be reconstructed Figure B 5 shows three occurrences of a waveform In Frame 1 the dotted points are sampled and the trigger occurs time t before the next sample In Frame 2 the square points are sampled and the trigger occurs time t before the next sample In Frame 3 the triangular points are sampled and the trigger occurs time t before the next sample With knowledge of the three times t t and tz you can reconstruct the waveform as if it had been sampled at a higher rate as shown at the bottom of the figure National Instruments Corporation B 5 NI 5112 User Manual Appen
32. her frequency signals if the analog bandwidth is wide enough to let the signal to pass through without attenuation A higher sample rate also captures more waveform details Figure B 3 illustrates a 1 MHz sine wave sampled by a 2 MS s ADC and a 20 MS s ADC The faster ADC digitizes 20 points per cycle of the input signal compared with 2 points per cycle with the slower ADC In this example the higher sample rate more accurately captures the waveform shape as well as frequency B 2 ni com Appendix B Digitizer Basics e a Tu m Sample Rate 2 MS s e Sample Rate 20 MS s Figure B 3 1 MHz Sine Wave Sample Vertical Sensitivity Vertical sensitivity describes the smallest input voltage change the digitizer can capture This limitation is because one distinct digital voltage encompasses a range of analog voltages Therefore a minute change in voltage at the input might not be noticeable at the output of the ADC This parameter depends on the input range gain of the input amplifier and ADC resolution it is specified in volts per LSB Figure B 4 shows the transfer function of a 3 bit ADC with a vertical range of 5 V having a vertical sensitivity of 5 8 V LSB National Instruments Corporation B 3 NI 5112 User Manual Appendix B Digitizer Basics A Range 0 5 V Voltage Fluctuations in This Region Will Be Unnoticed Figure B 4 Transfer Function of a 3 Bit ADC ADC Resolution ADC resoluti
33. ing rate the condition or state of an analog or digital signal NI 5112 User Manual Glossary F filtering gain H hardware harmonics Hz in input bias current input impedance instrument driver interrupt interrupt level VO ISA NI 5112 User Manual a type of signal conditioning that allows you to remove unwanted signals from the signal you are trying to measure the factor by which a signal is amplified sometimes expressed in decibels the physical components of a computer system such as the circuit boards plug in boards chassis enclosures peripherals cables and so on multiples of the fundamental frequency of a signal hertz per second as in cycles per second or samples per second inches the current that flows into the inputs of a circuit the measured resistance and capacitance between the input terminals of a circuit a set of high level software functions that controls a specific plug in DAQ board Instrument drivers are available in several forms ranging from a function callable language to a virtual instrument VI in LabVIEW a computer signal indicating that the CPU should suspend its current task to service a designated activity the relative priority at which a device can interrupt input output the transfer of data to from a computer system involving communications channels operator interface devices and or data acquisition and control interfaces industry standard
34. itively sampling a repeated waveform the smallest signal increment that can be detected by a measurement system Resolution can be expressed in bits or in digits The number of bits in a system is roughly equal to 3 3 times the number of digits root mean square a measure of signal amplitude the square root of the average value of the square of the instantaneous signal amplitude read only memory real time system integration bus the National Instruments timing bus that connects devices directly by means of connectors on top of the boards for precise synchronization of functions seconds samples in four wire resistance the sense measures the voltage across the resistor being excited by the excitation current the amount of time required for a voltage to reach its final value within specified limits samples per second used to express the rate at which an instrument samples an analog signal a measure of the amount of noise seen by an analog circuit or an ADC when the analog inputs are grounded the percentage that a measurement will vary according to temperature See also thermal drift measurements that change as the temperature varies NI 5112 User Manual Glossary thermal EMFs thermoelectric potentials transfer rate U undersampling update rate V V VAC VDC error VI Vims W waveform shape working voltage NI 5112 User Manual thermal electromotive forces voltages generated
35. l Instruments will at its option repair or replace equipment that proves to be defective during the warranty period This warranty 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 document 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 Natio
36. laves This pulse synchronizes the clock dividers on each NI 5112 3 Distribute the master trigger signal across the STAR bus lines to all devices 3 Note To make use of the STAR bus triggering the master has to reside in the STAR controller slot which is slot 2 in the PXI chassis Synchronizing Multiple PCI Devices NI 5112 User Manual To synchronize the NI 5112s for PCI clock dividers you must connect the boards with a National Instruments Real Time System Integration RTSI bus cable The RTSI bus is a dedicated high speed digital bus designed to facilitate system integration by low level high speed real time communication between National Instruments devices Using RTSI National Instruments devices are able to share high speed digital signals with no external cabling For PCI devices the physical bus interface is an internal 34 pin connector and signals are shared via a ribbon cable inside the PC enclosure The RTSI bus has seven bidirectional trigger lines and one bidirectional clock signal RTSI cables are available for chaining two three four or five devices together To synchronize multiple NI 5112s for PCI follow this procedure 1 Use the RTSI bus clock line to distribute the 10 MHz reference clock from the master to all slaves 2 Distribute a clock synchronization pulse through one of the RTSI trigger lines from master to slaves This pulse synchronizes the clock dividers on each NI 5112 3 Distribute the maste
37. lock input levels Sampling clock frequency Synchronization between boards Hysteresis Coupling Pretrigger depth A 2 1 MQ II 30 pF or 50 Q software selectable With 50 Q input impedance input signal should be below 1 Vms to maintain measurement accuracy 42 V DC peak AC 10 MHz PXI RTSI clock and 10 MHz onboard reference 50 ppm 1 minimum TTL 100 MHz fixed data can be decimated by n where 1 lt n lt 100e6 Via PXI backplane 10 MHz reference clock or digital trigger input NI 5112 for PXD via RTSI clock line or digital trigger input NI 5112 for PCI Edge hysteresis analog digital ChO Chl TRIG PFI lt 1 2 gt RTSI lt 0 6 gt PXI Star Rising falling Fully programmable DC or AC on CHO CH1 TRIG Up to 16 or 32 MB per channel depending on memory option purchased ni com DC accuracy Ch 0 Ch 1 eee DC accuracy TRIG eee eeeeeeeeeeees Bandwidth cescessssceeeseeeesseeeeseees TRIG input range oe eects TRIG input impedance TRIG input protection ee Acquisition Methods Random interleaved sampling RIS Real time sampling 00 0 cee eeeeeeeeeenees Power Requirements 43S MID CLIE eh BAR cease gece beeches sh SES VDC etp T E 12 VDC sees stiesevteeteniet cease toeee seta R Physical National Instruments Corporation A 3 Appendix A Specifications Up to 16 or 32 MB per channel depending on memory option purchased 100 us to
38. nal Instruments be liable for 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 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 co
39. ngs b Select NI 5112 from the instrument list as shown in Figure 1 3 If NI 5112 is not in the device list make sure you have properly configured the device using Measurement amp Automation Explorer MAX For more information on how to configure your NI 5112 in MAX refer to the Where to Start with Your Oscilloscope Digitizer documentation that shipped with your NI 5112 c Click OK to use these settings NI 5112 User Manual 1 4 ni com Chapter 1 Taking Measurements with the NI 5112 EF VirtualBench Scope Settings IVi gt 1 NI 5112 for PXI w Instrument Instrument List Acquire Display Output Tm Trigger Noise Rejection 0 0000 Trigger Holdoff mSec 1k Buffer Size Averaging Cancel Apply Figure 1 3 Acquire Tab of VirtualBench Scope Settings Dialog Box 3 Note When you launch VirtualBench Scope it automatically uses the settings of your previous VirtualBench Scope session 3 Enable the Ch 0 and or Ch 1 button in the channel selector area Disable all other channels Disabled channels have a gray frame around them 4 Click Auto Setup on the main control bar 5 Click Run to start the acquisition ays Note Refer to the VirtualBench Scope Online Help for additional help configuring VirtualBench Scope for your specific application National Instruments Corporation 1 5 NI 5112 User Manual Chapter 1 Taking Measurements with the NI 5112 Soft Front Panel Features
40. nship of voltage to current in a resistance a segment of the input range of an instrument outside of the normal measuring range Measurements can still be made usually with a degradation in specifications sampling at a rate greater than the Nyquist frequency the frequency range that a filter passes without attenuation 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 the absolute maximum or minimum amplitude of a signal AC DC Programmable Function Input the technique to acquire a programmed number of samples after trigger conditions are met the technique used on a device to keep a buffer filled with data so that when the trigger conditions are met the sample includes the data leading up to the trigger condition PCI eXtensions for Instrumentation PXI is an open specification that builds off the CompactPCI specification by adding instrumentation specific features resistor random access memory sampling that occurs immediately G 6 ni com random interleaved sampling resolution rms ROM RTSI bus sense settling time S s system noise T temperature coefficient thermal drift National Instruments Corporation G 7 Glossary method of increasing sample rate by repet
41. on limits the accuracy of a measurement The higher the resolution number of bits the more accurate the measurement An 8 bit ADC divides the vertical range of the input amplifier into 256 discrete levels With a vertical range of 10 V the 8 bit ADC cannot resolve voltage differences smaller than 39 mV In comparison a 12 bit ADC with 4 096 discrete levels can resolve voltage differences as small as 2 4 mV Record Length Record length refers to the amount of memory dedicated to storing digitized samples for postprocessing or display In a digitizer record length limits the maximum duration of a single shot acquisition For example with a 1 000 sample buffer and a sample rate of 20 MHz the duration of acquisition is 50 us the number of points multiplied by the acquisition time point or 1 000 x 50 ns With a 100 000 sample buffer and a sample rate of 20 MHz the duration of acquisition is 5 ms 100 000 x 50 ns NI 5112 User Manual B 4 ni com Appendix B Digitizer Basics Triggering Options One of the biggest challenges of making a measurement is to successfully trigger the signal acquisition at the point of interest Since most high speed digitizers actually record the signal for a fraction of the total time they can easily miss a signal anomaly if the trigger point is set incorrectly The NI 5112 is equipped with sophisticated triggering options such as trigger thresholds programmable hysteresis values and trigger hold off T
42. onent in your signal before it enters the PGA Activating AC coupling inserts a capacitor in series with the input You can select input coupling via software The boundary between DC and AC signals is called the AC coupling cutoff frequency Frequencies above this cutoff pass through to the PGA while frequencies below it are blocked As shown in the following figure adding an attenuator probe lowers this cutoff point 0 dB 3 dB Signal Strength 10x No Probe Probe Cutoff Cutoff Frequency Frequency Figure 2 2 Impact of Cutoff Frequencies with Attenuator Probes See Appendix B Digitizer Basics for more information on input coupling National Instruments Corporation 2 3 NI 5112 User Manual Chapter 2 Hardware Overview DC Offset NI 5112 User Manual DC offset positions a waveform around an arbitrary DC value Using DC offset allows you to examine small changes in the input signal which can improve the accuracy of your measurement For instance imagine that you are acquiring the waveform shown in Figure 2 3 that outputs 0 75 1 25 V Without using DC offset you would need to specify a range of 2 5 V 1 25 V to capture the waveform Since the input range is adjustable in 10 steps points would be acquired in 10 mV 2 5 V 256 intervals However if you centered the waveform around 1 V with DC offset you could limit the range to 0 5 V 0 25 V This would reduce each step from 10 mV to 2 mV
43. onformity DoC for information pertaining to the CE Mark compliance scheme The Manufacturer includes a DoC for most every hardware product except for those bought 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 Certain exemptions may apply in the USA see FCC Rules 15 103 Exempted devices and 15 105 c Also available in sections of CFR 47 The CE Mark Declaration of Conformity will contain important supplementary information and instructions for the user or installer Conventions lt gt bold italic monospace The following conventions are used in this manual Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name for example DBIO lt 3 0 gt The symbol leads you through nested menu items and dialog box options to a final action The sequence File Page Setup Options directs you to pull down the File menu select the Page Setup item and select Options from the last dialog box This icon denotes a note which alerts you to important information This icon denotes a warning which advises you of precautions to take to avoid being electrically shocked Bold text denotes items that you must select or click on in the software such as menu items and dialog box options Bold text also denotes parameter names
44. pyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks CVI LabVIEW National Instruments ni com 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 USE OF NATIONAL INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE U
45. quency input The NI 5112 can also output its 10 MHz reference clock to synchronize other NI 5112 devices or other equipment to the same reference clock Synchronizing Multiple PXI Devices The PXI bus has the following timing and triggering features that can be used to synchronize multiple NI 5112s e System Reference Clock This is a 10 MHz clock with 25 ppm accuracy It is independently distributed to each PXI peripheral slot through equal length traces with a skew of less than 1 ns between slots Multiple devices can use this common timebase for synchronization This allows each NI 5112 to phase lock to the system clock National Instruments Corporation 2 11 NI 5112 User Manual Chapter 2 Hardware Overview Trigger Bus This bus features eight bidirectional lines that link all PXI slots providing interdevice synchronization and communication The skew from slot to slot is less than 10 ns e Star Trigger This special trigger slot provides an independent dedicated bidirectional line for each of up to 13 peripheral slots on a single backplane All lines are matched in length which provides alow slot to slot skew of less than 1 ns A star trigger controller plugged into this slot can route triggers and clocks among peripheral slots To synchronize multiple NI 5112s follow this procedure 1 Distribute the PXI 10 MHz system reference clock to all devices 2 Distribute a clock synchronization pulse signal from the master to s
46. quires data continuously Deselecting this button places the VirtualBench Scope in idle mode Single instructs VirtualBench Scope to perform a single sweep acquisition Auto Setup configures the scope for the best timebase volts per division and trigger setting for each channel currently selected with the channel selector Mode sets the mode of the scope to either volts versus time or X versus Y mode Select CURSOR activates two cursors on the waveform display e The zoom controls adjust the view of your display data Click the magnifying glass icon to zoom in on the displayed data Click the arrows to the right of the magnifying glass to zoom out to full scale e Timebase controls the length of time period that is displayed Turn the knob clockwise to reduce the time period Each horizontal division represents one time period Sy Note Refer to the VirtualBench Scope Online Help for additional help on the front panel items Safety Information The following paragraphs contain important safety information concerning hazardous voltages and hazardous operating conditions Please adhere to these safety instructions while configuring or connecting signals to the NI 5112 AN Warnings Shock Hazard Only qualified personnel aware of the dangers involved should install this unit Disconnect all power before installing or removing the device If signal wires are connected to the device dangerous voltages may exist even when
47. r 2 Hardware Overview Figure 2 7 shows a timing diagram of signals when hold off is enabled and the hold off time is longer than posttriggered acquisition Trigger Hold Off Acquisition In Progress iV x v x Posttrigger re i fpa gt Data Pretrigger 1 1 Li Data 1 Hold Off Time in nanoseconds gt Adjustable between 100 us and 171 79 s rc X Trigger Not Accepted V Trigger Accepted Memory Figure 2 7 Timing with Hold Off Enabled The NI 5112 acquires samples into onboard memory before transferring them to the host computer The minimum size for a buffer is approximately 256 8 bit samples although you can specify smaller buffers in software When specifying a smaller buffer size the minimum number of points are still acquired into onboard memory but only the specified number of points are transferred into the host computer s memory Multiple Record Acquisitions NI 5112 User Manual You can configure the NI 5112 so that after a trigger has been received and the posttrigger samples have been stored it automatically begins another acquisition that is stored in another memory record on the device This process is a multiple record acquisition To perform multiple record acquisitions configure the NI 5112 for the number of records to be acquired then start the acquisition The NI 5112 acquires an additional record each time a trigger is accepted until
48. r accurate measurements you should use the right settings when acquiring data with your NI 5112 Knowing the characteristics of the signal in consideration helps you to choose the correct settings Such characteristics include e Peak to peak value This parameter in units of volts reflects the maximum change in signal voltage If V is the signal voltage at any given time then Vpk to pk Vmax Vmin The peak to peak value affects the vertical sensitivity or gain of the input amplifier If you do not know the peak to peak value start with the largest input range and decrease it until the waveform is digitized using the maximum dynamic range without clipping the signal Refer to Appendix A Specifications for the maximum input range for your NI 5112 Figure B 7 shows how different ranges affect the resolution of the signal you acquire National Instruments Corporation B 7 NI 5112 User Manual Appendix B Digitizer Basics 127 LSB 47 LSB 5p oo lt 0 LSB 7 LSB Sescin a SNe fico ee Nie Zeek eee eZee eee 128 LSB a Input Range 10 V Number of LSBs 15 36 600 mV 10 V x 256 LSBs 15 36 LSB 127 LSB 128 LSB b Input Range 1 V Number of LSBs 153 6 600 mV 1 V x 256 LSBs 153 6 LSB 153 LSB 127 LSB 0 LSB Acquired Signal 128 LSB 154 LSB c Input Range 500 mV Number of LSBs 307 2 600 mV 500 mV x 256 LSBs 307 2 LSB Figure B 7 Dynamic Range of an 8
49. r trigger signal through one of the designated RTSI trigger lines to all slaves 2 12 ni com Chapter 2 Hardware Overview PFI Lines and Synchronization The NI 5112 has two front panel digital lines that can accept a trigger accept or generate a reference clock or output a square wave of programmable frequency With PFI lines you can synchronize to third party equipment that may not use the RTSI or the PXI timing and triggering buses The function of each PFI line is independent however only one trigger source can be accepted during acquisition PFI Lines as Inputs You can select PFI1 or PFI2 as an input for a trigger or a reference clock For instance you can accept a 10 MHz reference clock from an external source rather than using the PXI backplane 10 MHz system reference clock or the clock of another NI 5112 through the RTSI clock line PFI Lines as Outputs You can select PFI1 or PFI2 to output several digital signals e Reference Clock is a 10 MHz TTL level clock signal You can use the reference clock to synchronize another NI 5112 configured as a slave device residing in another PCI or PXI chassis or other equipment that can accept a 10 MHz reference clock e Frequency Output is a 1 kHz digital pulse train signal with a 50 duty cycle which means that the signal is high and low for the same length of time Commonly the Frequency Output signal provides a signal for compensating a passive probe e Trigger Output is a
50. re automatically coerces the requested range up to the first available range The input impedance of the NI 5112 is software selectable between 50 Q and 1 MQ The output impedance of the device connected to the NI 5112 and the input impedance of the NI 5112 form an impedance divider which attenuates the input signal according to the following formula yV V Rin m x x where V is the measured voltage V is the source voltage R is the output impedance of the external device and R is the input impedance If the device you are measuring has a very large output impedance your measurements will be affected by this impedance divider For example if the device has 1 MQ output impedance and you have selected the 1 MQ input impedance of the NI 5112 your measured signal will be half the actual signal value 2 2 ni com Chapter 2 Hardware Overview When performing measurements on systems that are expected to be terminated with a 50 Q load you can select the 50 Q input impedance of the NI 5112 With 50 Q input impedance selected the input signal should be limited to 1 Vs Signals larger than this will not damage the NI 5112 but your measurements may be inaccurate When the input reaches about 7 Vims an overload protection relay will open and the device will revert to 1 MQ impedance AC Coupling When you need to measure a small AC signal on top of a large DC component you can use AC coupling AC coupling rejects any DC comp
51. rnal calibration can be executed without any external equipment connected External calibration which is performed much less frequently is used to recalibrate the device when the specified calibration interval has expired External calibration requires you to connect an external precision instrument to the device Internally Calibrating the NI 5112 NI 5112 User Manual There are a couple of simple ways to internally calibrate the NI 5112 You can use the VirtualBench Scope front panel for calibration by selecting Calibrate from the Utility menu You can also use the calibration example for your ADE to calibrate the device See the Programmatically Controlling Your NI 5112 section for information on where to find these examples When Internal Calibration Is Needed To provide the maximum accuracy independent of temperature changes the NI 5112 needs to be recalibrated when the environmental conditions change in your PC beyond a specified temperature range Since the environment inside your system is most likely different from the environment under which the device was initially calibrated you should recalibrate your device after installing it in your system Be sure to first wait at least 15 minutes for your system to warm up to its operating temperature What Internal Calibration Does By executing a software command you can internally calibrate the NI 5112 without connecting any external equipment Internal calibration uses a precision
52. sion This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures e Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver e Connect the equipment into an outlet on a circuit different from that to which the receiver is connected e Consult the dealer or an experienced radio TV technician for help Canadian Department of Communications This Class B digital apparatus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet appareil num rique de la classe B respecte toutes les exigences du R glement sur le mat riel brouilleur du Canada European Union Compliance to EEC Directives Readers in the EU EEC EEA must refer to the Manufacturer s Declaration of C
53. ssbe devastate sctee ks 24 hours or any time temperature changes beyond 2 C from temperature at which last internal calibration was performed Extemtiall teeccss Sess Sectboyet cca avec aa Internal reference requires external recalibration Intetval innsats 5 years Warm Up time oo enr nne 15 minutes National Instruments Corporation A 5 NI 5112 User Manual Digitizer Basics This appendix explains basic information you need to understand about making measurements with digitizers including important terminology Understanding Digitizers Nyquist Theorem National Instruments Corporation B 1 To understand how digitizers work you should be familiar with the Nyquist theorem and how it affects analog bandwidth and sample rate You should also understand terms including vertical sensitivity analog to digital converter ADC resolution record length and triggering options The Nyquist theorem states that a signal must be sampled at least twice as fast as the bandwidth of the signal to accurately reconstruct the waveform otherwise the high frequency content will alias at a frequency inside the spectrum of interest passband An alias is a false lower frequency component that appears in sampled data acquired at too low a sampling rate Figure B 1 shows a 5 MHz sine wave digitized by a 6 MS s ADC The dotted line indicates the aliased signal recorded by the ADC at that sample rate MAT Figure B 1 Sine Wave Demons
54. sses These classes are known as Class A for use in industrial commercial locations only or Class B for use in residential or commercial locations Depending on where it is operated this product could be subject to restrictions in the FCC rules In Canada the Department of Communications DOC of Industry Canada regulates wireless interference in much the same way Digital electronics emit weak signals during normal operation that can affect radio television or other wireless products By examining the product you purchased you can determine the FCC Class and therefore which of the two FCC DOC Warnings apply in the following sections Some products may not be labeled at all for FCC if so the reader should then assume these are Class A devices FCC Class A products only display a simple warning statement of one paragraph in length regarding interference and undesired operation Most of our products are FCC Class A The FCC rules have restrictions regarding the locations where FCC Class A products can be operated FCC Class B products display either a FCC ID code starting with the letters EXN Trade Name Model Number or the FCC Class B compliance mark that appears as shown here on the right FE Tested to Comply with FCC Standards Consult the FCC web site http www fcc gov for more information FCC DOC Warnings This equipment generates and uses radio frequency energy and if not installed and used in strict accordance with the in
55. structions in this manual and the CE Mark Declaration of Conformity may cause interference to radio and television reception Classification requirements are the same for the Federal Communications Commission FCC and the Canadian Department of Communications DOC FOR HOME OR OFFICE USE Changes or modifications not expressly approved by National Instruments could void the user s authority to 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 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense Canadian Department of Communications This Class A digital apparatus meets all requirements of the Canadian Interference Causing Equipment Regulations Cet appareil num rique de la classe A respecte toutes les exigences du R glement sur le mat riel brouilleur du Canada Class B Federal Communications Commis
56. sves costs teeasiess ts E E A azeeanieraazees seeds 2 5 ACQUISItLON SySteim sionerien o i eie satin obey EEEE E A E EE E 2 5 Acquisiton MOE siciselscastssdoessastetaccecnscecadsaltbesiveedvestadasessSuaistagdesesedsesssbaaseeeg ses 2 5 Calibration en ate ar a EE E A E A E Saagdvacutes asset es as vedees eee 2 6 Internally Calibrating the NI 5112 ssessseessesesesssseerssrsrssrsreersresrrsrsrrsrsresreseeeee 2 6 When Internal Calibration Is Needed nseenseeseeeeeeeeseeereseerrerseese 2 6 What Internal Calibration Does ssssesssessseesserereereresrsresrrsrsrrsresesre 2 6 Extemal Calibrations enn nn eines e NAE a A ol ates tees cases 2 7 Prigseritigeamd AMNS oeren E E A E TEA E 2 7 Analog Trigger Circuits pin a E Ay 2 8 High Hysteresis Analog Triggering Mode seseeeseeeeeereseererreere 2 8 Low Hysteresis Analog Triggering Mode seeseeseeeereerrsrerrersee 2 8 Rising Edge Analog Trigger eesseeseseseeeesreersrrsrerrererresesrrsesrrsrssrsres 2 9 Falling Edge Analog Trigger esseeeseeseeesseersresrsresreresresrrsesrrersresrse 2 9 Pris eer FOLDS OGL ernn inu ie EEr e EERE E EE P ES EE AET AEE ENS 2 9 Me M Of Ys tes tcc ist a R E E ia A OE 2 10 Multiple Record Acquisitions 0 cece eseeseceeceseeseeeseeseesseeseesseesecesecaeeneeeaesneeeseenaes 2 10 National Instruments Corporation vil NI 5112 User Manual Contents Synchronizing Multiple Devices 0 eee eee ceeeeseeseeeeeeseeeceeaeceeeeaeeeees
57. trating the Nyquist Frequency The 5 MHz frequency aliases back in the passband falsely appearing as a 1 MHz sine wave To prevent aliasing in the passband a lowpass filter limits the frequency content of the input signal above the Nyquist rate NI 5112 User Manual Appendix B Digitizer Basics Analog Bandwidth Analog bandwidth describes the frequency range in Hertz in which a signal can be digitized accurately This limitation is determined by the inherent frequency response of the input path which causes loss of amplitude and phase information Analog bandwidth is the frequency at which the measured amplitude is 3 dB below the actual amplitude of the signal This amplitude loss occurs at very low frequencies if the signal is AC coupled and at very high frequencies regardless of coupling When the signal is DC coupled the bandwidth of the amplifier will extend all the way to the DC voltage Figure B 2 illustrates the effect of analog bandwidth on a high frequency signal The result is a loss of high frequency components and amplitude in the original signal as the signal passes through the instrument Input Signal Bandwidth Instrument Measured Signal Sample Rate NI 5112 User Manual Figure B 2 Analog Bandwidth Sample rate is the rate at which a signal is sampled and digitized by an ADC According to the Nyquist theorem a higher sample rate produces accurate measurement of hig
58. ular square and saw tooth waves Some of the more elusive waveforms such as irregular pulse trains runt pulses and transients may be more difficult to capture Figure B 8 shows an example of a difficult pulse train trigger V 5V4 Trigger Level Hold off 1 and 3 Trigger Accepted 2 and 4 Trigger Ignored National Instruments Corporation Figure B 8 Difficult Pulse Train Signal Ideally the trigger event should occur at condition one but sometimes the instrument may trigger on condition two because the signal crosses the trigger level You can solve this problem without using complicated signal processing techniques by using trigger hold off which lets you specify a time from the trigger event to ignore additional triggers that fall within that time With an appropriate hold off value the waveform in Figure B 8 can be properly captured by discarding conditions two and four B 9 NI 5112 User Manual Appendix B Digitizer Basics e Input coupling You can configure the input channels on your NI 5112 to be DC coupled or AC coupled DC coupling allows DC and low frequency components of a signal to pass through without attenuation In contrast AC coupling removes DC offsets and attenuates low frequency components of a signal This feature can be exploited to zoom in on AC signals with large DC offsets such as switching noise on a 12 V power supply Refer to Appendix
59. uments Corporation 2 7 NI 5112 User Manual Chapter 2 Hardware Overview Analog Trigger Circuit The analog trigger on the NI 5112 operates by comparing the current analog input to an onboard threshold voltage This threshold voltage the trigger value can be set to any voltage within the current input range A hysteresis value associated with the trigger is used to create a trigger window the signal must pass through before the trigger is accepted Triggers can be generated on a rising edge or falling edge condition as illustrated in the following two figures High Hysteresis Analog Triggering Mode In high hysteresis analog triggering mode the trigger is generated when a signal crosses above the hysteresis value and then crosses above the trigger value The signal must cross back below the hysteresis value before another trigger is generated Trigger Value Hysteresis Value Trigger Events A Trigger Figure 2 5 High Hysteresis Analog Triggering Mode Low Hysteresis Analog Triggering Mode In low hysteresis analog triggering mode the trigger is generated when the signal crosses below the hysteresis value and then crosses the trigger value The signal must cross back above the hysteresis value before another trigger is generated NI 5112 User Manual 2 8 ni com Chapter 2 Hardware Overview Hysteresis Value Trigger Value Trigger Events Trigger

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