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Chapter 3

Hardware Overview

©

National Instruments Corporation

3-7

NI PXIe-6672 User Manual

The remainder of this chapter describes how these signals are used,
acquired, and generated by the NI PXIe-6672 hardware, and explains
how you can route the signals between various locations to synchronize
multiple measurement devices and PXI chassis.

Clock Generation

The NI PXIe-6672 can generate two types of clock signals. The first clock
is generated using the onboard DDS chip, and the second is generated with
a precise 10 MHz oscillator. The following sections describe the two types
of clock generation and explain the considerations for choosing either type.

Direct Digital Synthesis (DDS)

DDS is a method of generating a clock with programmable frequency.
DDS consists of a

frequency tuning word

, an accumulator, a sine-lookup

table, a D/A converter (DAC), and a comparator.

The frequency tuning word is a number that specifies the desired
frequency. Each master clock cycle, the frequency tuning word is added to
the accumulator, which rolls over when it gets to its maximum value. The
accumulator value is used to get a point in the sine-lookup table, which is
converted to an analog voltage by the DAC. For example, if the sine table
is 128 points long, and the frequency tuning word is one, the accumulator
takes 128 clock cycles to output one sine wave. If you change the frequency
tuning word to 3, the accumulator steps through the sine table three times
as fast, and outputs a sine wave in 128/3, or 42.6, clock cycles.

The output of the DAC is run through an analog filter to smooth the sine
wave. The filtered output is then run through a comparator, which changes
the output to a square wave with the specified frequency.

You can specify the programmable DDS frequency on the NI PXIe-6672
with a precision of approximately .07 Hz within the range 1 Hz to
105 MHz. The accuracy of the frequency depends on the PXI_CLK10
reference clock, so a precise 10 MHz source improves the accuracy of the
DDS output. You can replace the 10 MHz clock with the TCXO for more
accurate DDS timing.

When the DDS is programmed an update signal must be sent to it before it
will begin operating as programmed. The source for this update signal is
either immediate (DDS starts outputting the programmed frequency as
soon as software programs it) or one of the eight PXI triggers. When one

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Содержание Network Adapter NI PXIe-6672

Страница 1: ...PXI Express NI PXIe 6672 User Manual Timing and Synchronization Module for PXI Express NI PXIe 6672 User Manual June 2008 372185F 01 ...

Страница 2: ...Lebanon 961 0 1 33 28 28 Malaysia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210 311 210 Russia 7 495 783 6851 Singapore 1800 226 5886 Slovenia 386 3 425 42 00 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 2005151 Taiwan 886 02 2377 2222 Thailand 6...

Страница 3: ...ding photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation National Instruments respects the intellectual property of others and we ask our users to do the same NI software is protected by copyright and other intellectual property laws Where NI software may be used to reproduce soft...

Страница 4: ...nstalling and Configuring Installing the Software 2 1 Installing the Hardware 2 1 Configuring the Module 2 2 Chapter 3 Hardware Overview NI PXIe 6672 Front Panel 3 3 Access LED 3 4 Active LED 3 4 Connectors 3 5 Hardware Features 3 5 Clock Generation 3 7 Direct Digital Synthesis DDS 3 7 PXI_CLK10 and TCXO 3 8 Routing Signals 3 9 Determining Sources and Destinations 3 11 Using Front Panel PFIs As In...

Страница 5: ...ating a Single Pulse Global Software Trigger 3 18 Using the PXI_CLK10 PLL 3 19 Chapter 4 Calibration Factory Calibration 4 1 TCXO Frequency 4 1 PXI_CLK10 Phase 4 1 DDS Start Trigger Phase 4 1 DDS Initial Phase 4 2 Additional Information 4 2 Appendix A Specifications Appendix B Technical Support and Professional Services Glossary Index ...

Страница 6: ...or example AO 3 0 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 tip which alerts you to advisory information This icon denotes a note which alerts you to important information This icon denot...

Страница 7: ...ion you have as follows Measurement hardware documentation This documentation contains detailed information about the measurement hardware that plugs into or is connected to the computer Use this documentation for hardware installation and configuration instructions specifications about the measurement hardware and application hints Software documentation Refer to the NI Sync User Manual available...

Страница 8: ...tem What You Need to Get Started To set up and use the NI PXIe 6672 you need the following items NI PXIe 6672 Timing and Triggering Module NI PXIe 6672 User Manual NI Sync CD An Application Development Environment such as LabVIEW LabWindows CVI Microsoft Visual C MSVC PXI Express chassis PXI Express embedded controller or a desktop computer connected to the PXI Express chassis using MXI Express ha...

Страница 9: ... or any sign of damage Notify NI if the module appears damaged in any way Do not install a damaged module into the computer Store the NI PXIe 6672 in the antistatic envelope when not in use Software Programming Choices When programming the NI PXIe 6672 you can use NI application development environment ADE software such as LabVIEW or LabWindows CVI or you can use other ADEs such as Visual C C LabV...

Страница 10: ...onmetallic brush The product must be completely dry and free from contaminants before you return it to service Operate the product only at or below Pollution Degree 2 Pollution is foreign matter in a solid liquid or gaseous state that can reduce dielectric strength or surface resistivity The following is a description of pollution degrees Pollution Degree 1 means no pollution or only dry nonconduc...

Страница 11: ...ch as that provided by a standard wall outlet for example 115 V for U S or 230 V for Europe Examples of Installation Category II are measurements performed on household appliances portable tools and similar products Installation Category III is for measurements performed in the building installation at the distribution level This category refers to measurements on hard wired equipment such as equi...

Страница 12: ...e NI PXIe 6672 hardware Installing the Hardware The following are general installation instructions Consult the chassis user manual or technical reference manual for specific instructions and warnings about installing new modules 1 Power off and unplug the chassis 2 Locate the System Timing Slot in your chassis It is marked by either a square glyph shown in Figure 2 1 or a square glyph with a circ...

Страница 13: ...backplane connectors 6 Insert the NI PXIe 6672 into the PXI Express slot Use the injector ejector handle to fully insert the module into the chassis 7 Screw the front panel of the device to the front panel mounting rail of the chassis 8 Visually verify the installation Make sure the module is not touching other modules or components and is fully inserted into the slot 9 Plug in and power on the ch...

Страница 14: ...ments Corporation 3 1 NI PXIe 6672 User Manual 3 Hardware Overview This chapter presents an overview of the hardware functions of the NI PXIe 6672 Figure 3 1 provides a functional overview of the NI PXIe 6672 hardware ...

Страница 15: ... 7 CLKOUT DDS CLKIN AC Coupled Clock Detector PLL PXI_CLK10_IN TCXO Calibration DAC TCXO Clock PXI_CLK10 DDS Clock PFI 0 Threshold DAC PFI 0 Driver Comparator PFI 1 Driver Comparator PFI 2 Driver Comparator PFI 3 Driver Comparator PFI 4 Driver Comparator PFI 5 Driver Comparator PFI 2 Threshold DAC TCXO PFI 1 Threshold DAC PFI 3 Threshold DAC PFI 4 Threshold DAC PFI 5 Threshold DAC CLKIN ...

Страница 16: ...t Panel Figure 3 2 shows the connectors and LEDs on the front panel of the NI PXIe 6672 Figure 3 2 NI PXIe 6672 Front Panel 1 Access LED 2 Active LED 3 CLKOUT Connector 4 CLKIN Connector 5 PFI 0 5 Connectors NI PXIe 6672 Timing Module CLK OUT PFI 0 PFI 1 PFI 2 PFI 3 PFI 4 PFI 5 CLK IN ACCESS ACTIVE 1 2 3 4 5 ...

Страница 17: ... helpful when you want to identify devices in a multichassis situation or when you want an indication that your application has reached a predetermined section of the code Table 3 2 illustrates the meaning of each Active LED color Note A red Active LED can indicate that either PXI_CLK10 has stopped or that there is a PLL error Table 3 1 Access LED Color Indication Color Status Off Module is not ye...

Страница 18: ...0 5 Programmable Function Interface 0 5 These connectors can be used for either input or output Additionally PFI 0 can be used as a clock input for internally synchronizing other signals Refer to the Synchronous Routing section for more information about this functionality You can program the behavior of these PFI connections individually Refer to Figure 3 2 for a diagram showing the locations of ...

Страница 19: ... the TCXO or as a source for routing to PXI_STAR CLKOUT Out CLKOUT is the signal on the SMB output pin of the same name Either the TCXO clock DDS clock or PXI_CLK10 may be routed to this location DDS Clock Out This is the output of the DDS The DDS frequency can be programmed with fine granularity from 1 Hz to 105 MHz The DDS chip automatically phase locks to PXI_CLK10 PXI_STAR 0 16 In Out The PXI ...

Страница 20: ...accumulator value is used to get a point in the sine lookup table which is converted to an analog voltage by the DAC For example if the sine table is 128 points long and the frequency tuning word is one the accumulator takes 128 clock cycles to output one sine wave If you change the frequency tuning word to 3 the accumulator steps through the sine table three times as fast and outputs a sine wave ...

Страница 21: ...rigger signals The NI PXIe 6672 DDS can adjust the phase of the generated clock by up to 5 ns This may be used to tighten the synchronization between two or more DDS devices in a multi chassis setup or to compensate for delays caused by different cable lengths PXI_CLK10 and TCXO The NI PXIe 6672 features a precision 10 MHz TCXO The frequency accuracy of this clock is several orders of magnitude gr...

Страница 22: ...ng Signals The NI PXIe 6672 has versatile trigger routing capabilities It can route signals to and from the front panel the PXI triggers and the PXI star triggers The CLKIN SMB input on the NI PXIe 6672 may be used for PXI_CLK10 replacement by either routing a 10 MHz signal directly from the CLKIN input to PXI_CLK10_IN or by using the CLKIN input as a phase lock reference for the TCXO When phase l...

Страница 23: ...CLK10 2N 2M PFI 0 DDS PXI_CLK10 2N 2M Selection Circuitry Selection Circuitry PFI 0 PFI 1 PFI 5 Selection Circuitry Selection Circuitry Selection Circuitry Selection Circuitry Selection Circuitry PXI_TRIG 0 PXI_TRIG 1 PXI_TRIG 7 Selection Circuitry Selection Circuitry 3 SYNCHRONIZATION CLOCKS for PFI 0 5 28 SOURCE 3 PXI_STAR 0 16 PXI_TRIG 0 7 PFI 0 5 and Software Trigger are routed to SOURCE of ea...

Страница 24: ...ons All signal routing operations can be characterized by a source input and a destination In addition synchronous routing operations must also define a third signal known as the synchronization clock Refer to the Choosing the Type of Routing section for more information on synchronous versus asynchronous routing PFI 0 5 PXI_TRIG 0 7 PXI_STAR 0 16 Software Trigger GND CLK CLK N CLK M SYNCHRONIZATI...

Страница 25: ...with a 50 Ω output The voltage thresholds for the front panel PFI inputs are programmable The input signal is generated by comparing the input voltage on the Table 3 4 Sources and Destinations for NI PXIe 6672 Signal Routing Operations Sources Destinations Front Panel Backplane Onboard Front Panel CLKOUT PFI 0 5 PXI_ CLK10_IN PXI_Star Trigger 0 16 PXI TRIG 0 7 TCXO Reference PLL CLKIN PFI 0 5 Back...

Страница 26: ...urce and the destination You also can drive a 50 Ω cable with a high impedance load The destination sees a single step to 3 3 V but the source sees a reflection This cable configuration is acceptable for low frequency signals or short cables You can select the signal source from the front panel triggers PFI 0 5 the PXI star triggers the PXI triggers or the synchronization clock PXI_CLK10 the DDS c...

Страница 27: ...iggers should not exceed 20 MHz to preserve signal integrity The signals do not reach each slot at precisely the same time A difference of several nanoseconds between slots can occur in an eight slot chassis However this delay is not a problem for many applications You can route signals to the PXI triggers from PFI 0 5 from the PXI star triggers or from other PXI triggers You also can route PXI_CL...

Страница 28: ... typical upper limit for the skew in most NI PXI chassis is 500 ps The low skew of the PXI star trigger bus is useful for applications that require triggers to arrive at several modules nearly simultaneously The star trigger lines are bidirectional so signals can be sent to System Timing Slot from a module in another slot or from System Timing Slot to the other module You can independently select ...

Страница 29: ... among NI PXIe 6672 modules depending on variations in temperature and chassis voltage Typical delay times in the NI PXIe 6672 for asynchronous routes between various sources and destinations are given in Appendix A Specifications Asynchronous routing works well if the total system delays are not too long for the application Propagation delay could be caused by the following reasons Output delay o...

Страница 30: ...6 shows a timing diagram that illustrates synchronous routing Figure 3 6 Synchronous Routing Operation Synchronous routing can send triggers to several places in the same clock cycle or send the trigger to those same places after a deterministic skew of a known number of clock cycles If a signal arrives at two chassis within the same clock cycle each NI PXIe 6672 realigns the signal with the synch...

Страница 31: ... include any front panel PFI pin any PXI star trigger line or any PXI trigger line The synchronization clock for a synchronous route can be any of the following signals 10 MHz PXI backplane clock signal DDS clock on the NI PXIe 6672 Front panel PFI 0 Input One of two divided copies of any of the previously listed three signals The NI PXIe 6672 includes two clock divider circuits that can divide th...

Страница 32: ...delay on the backplane These delays tend to be similar for chassis of the same model so routing the same clock to a pair of chassis usually matches PXI_CLK10 to within a few nanoseconds The third option is to employ the NI PXIe 6672 PLL circuitry for the TCXO As in option 1 the output of the TCXO replaces the native 10 MHz signal However this scheme also requires an input signal on CLKIN This sign...

Страница 33: ...plane The feedback in the PLL comes from PXI_CLK10 This PLL makes it possible for the NI PXIe 6672 to align clock edges at CLKIN with the edges of PXI_CLK10 that the modules receive If you split an external accurate 10 MHz reference and route it to two chassis they can both lock to it The result is a tighter synchronization of PXI_CLK10 on the chassis ...

Страница 34: ...nd storing four calibration constants These values control the accuracy of four features of the device which are discussed in the following sections TCXO Frequency The TCXO frequency can be varied over a small range The output frequency of the TCXO is adjusted using this constant to meet the specification listed in Appendix A Specifications This calibration applies only to the NI PXIe 6672 PXI_CLK...

Страница 35: ...om DDS Initial Phase The phase of the DDS output is adjusted using this constant so that the DDS outputs from multiple NI PXIe 6672 modules are aligned Additional Information Refer to ni com calibration for additional information on NI calibration services ...

Страница 36: ...requirement For PLL and TCXO 5 0 ppm For replacing PXI_CLK10 no PLL 100 ppm3 1 CLKIN fundamental frequency can be any multiple of 1 MHz within the range specified when the PLL is engaged and PXI_CLK10 is locking to it The frequency must be 10 MHz when replacing PXI_CLK10 without the PLL 2 Stresses beyond those listed can cause permanent damage to the device Exposure to absolute maximum rated condi...

Страница 37: ...XI_CLK10 10 MHz From TCXO 10 MHz From DDS 1 MHz1 to 105 MHz Duty cycle 43 to 55 2 Output impedance 50 Ω nominal Output coupling AC Amplitude software configurable to two voltage levels low and high drive 1 The lower limit is load dependent because of the AC coupling This limit is less than 1 MHz for high impedance loads 2 The duty cycle specification covers both DDS range and TCXO Open Load Square...

Страница 38: ...0 7 output 19 to 26 ns typical PFI 0 5 to PXI_STAR 0 12 output 10 to 19 ns typical Synchronized trigger input setup time tsetup 2 16 5 ns typical Synchronized trigger input hold time thold 2 9 9 ns typical 1 Stresses beyond those listed can cause permanent damage to the device Exposure to absolute maximum rated conditions for extended periods of time can affect device reliability Functional operat...

Страница 39: ...I PXIe 6672 backplane connector 300 ps3 typical Asynchronous delays tpd PXI_STAR 0 16 to PFI 0 5 output 13 to 17 ns typical PXI_STAR 0 16 to PXI_TRIG 0 7 output 18 to 24 ns typical 1 Stresses beyond those listed can cause permanent damage to the device Exposure to absolute maximum rated conditions for extended periods of time can affect device reliability Functional operation of the device outside...

Страница 40: ...ppm DDS Characteristics Frequency range 1 Hz to 105 MHz Frequency resolution 0 075 Hz Frequency accuracy Equivalent to PXI_CLK10 accuracy3 Physical Chassis requirement One 3U PXI Express System Timing Slot Front panel connectors SMB male 50 Ω Front panel indicators Two tricolor LEDs green red and amber 1 Includes stability of TCXO and supporting circuitry 2 Includes temperature stability of TCXO a...

Страница 41: ...taminants before returning it to service Operating Environment Ambient temperature range 0 to 55 C Tested in accordance with IEC 60068 2 1 and IEC 60068 2 2 Meets MIL PRF 28800F Class 3 low temperature limit and MIL PRF 28800F Class 2 high temperature limit Relative humidity range 10 to 90 noncondensing Tested in accordance with IEC 60068 2 56 1 Cable length measurements were made with an RG 58 ca...

Страница 42: ...ass 2 limits Random vibration Operating 5 to 500 Hz 0 3 grms Nonoperating 5 to 500 Hz 2 4 grms Tested in accordance with IEC 60068 2 64 Nonoperating test profile exceeds the requirements of MIL PRF 28800F Class 3 Note Specifications are subject to change without notice Safety This product is designed to meet the requirements of the following standards of safety for electrical equipment for measure...

Страница 43: ...atibility Directive EMC Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain the DoC for this product visit ni com certification search by model number or product line and click the appropriate link in the Certification column Environmental Management National Instruments is committed to designing and manufacturing products...

Страница 44: ... must be sent to a WEEE recycling center For more information about WEEE recycling centers and National Instruments WEEE initiatives visit ni com environment weee htm ᄤֵᙃѻક ᶧ ࠊㅵ ࡲ Ё RoHS Ё ᅶ National Instruments ヺড়Ё ᄤֵᙃѻકЁ䰤ࠊՓ ᶤѯ ᆇ 䋼ᣛҸ RoHS Ǆ Ѣ National Instruments Ё RoHS ড়㾘ᗻֵᙃˈ䇋ⱏᔩ ni com environment rohs_chinaǄ For information about China RoHS compliance go to ni com environment rohs_china ...

Страница 45: ... Service Program Membership This program entitles members to direct access to NI Applications Engineers via phone and email for one to one technical support as well as exclusive access to on demand training modules via the Services Resource Center NI offers complementary membership for a full year after purchase after which you may renew to continue your benefits For information about other techni...

Страница 46: ...uct by visiting ni com certification Calibration Certificate If your product supports calibration you can obtain the calibration certificate for your product at ni com calibration If you searched ni com and could not find the answers you need contact your local office or NI corporate headquarters Phone numbers for our worldwide offices are listed at the front of this manual You also can visit the ...

Страница 47: ... milli 10 3 k kilo 103 M mega 106 Symbols percent plus or minus positive of or plus negative of or minus per degree Ω ohm A accumulator A part where numbers are totaled or stored ADE application development environment asynchronous A property of an event that occurs at an arbitrary time without synchronization to a reference clock ...

Страница 48: ... output pin of the same name Either the OCXO clock or PXI_CLK10 can be routed to CLKOUT clock Hardware component that controls timing for reading from or writing to groups CompactPCI A Eurocard configuration of the PCI bus for industrial applications D D A digital to analog DAC digital to analog converter an electronic device that converts a digital number into a corresponding analog voltage or cu...

Страница 49: ...trostatic discharge F frequency The basic unit of rate measured in events or oscillations per second using a frequency counter or spectrum analyzer Frequency is the reciprocal of the period of a signal frequency tuning word A number that specifies the frequency front panel The physical front panel of an instrument or other hardware H Hz hertz the number of scans read or updates written per second ...

Страница 50: ...of your National Instruments DAQ GPIB IMAQ IVI Motion VISA and VXI devices N NI DAQ National Instruments driver software for DAQ hardware O oscillator A device that generates a fixed frequency signal An oscillator most often generates signals by using oscillating crystals but also may use tuned networks lasers or atomic clock sources The most important specifications on oscillators are frequency a...

Страница 51: ...f an instrument and its capability to give the same measurement over and over again for the same input signal propagation delay The amount of time required for a signal to pass through a circuit PXI A rugged open system for modular instrumentation based on CompactPCI with special mechanical electrical and software features The PXIbus standard was originally developed by National Instruments in 199...

Страница 52: ...puter or peripheral device controlled by another computer slot The place in the computer or chassis in which a card or module can be installed SMB sub miniature type B a small coaxial signal connector that features a snap coupling for fast connection synchronous A property of an event that is synchronized to a reference clock T tCtoQ clock to output time thold hold time tpd propagation delay time ...

Страница 53: ...tip 3 4 CLKIN connector description 3 5 location diagram 3 3 specifications A 1 CLKOUT connector description 3 5 location diagram 3 3 signal description table 3 6 specifications A 2 clock generation DDS 3 7 overview 3 7 PXI_CLK10 and TCXO 3 8 color Access LED color explanation table 3 4 Active LED color explanation table 3 4 configuring the device Access LED 3 4 Active LED 3 4 overview 2 2 convent...

Страница 54: ...erating a single pulse trigger 3 18 getting started configuring the device 2 2 equipment 1 1 installing the hardware 2 1 installing the software 2 1 software programming choices 1 2 unpacking 1 2 global software trigger generating a single pulse 3 18 using front panel PFIs as outputs 3 13 using the PXI star triggers 3 15 using the PXI triggers 3 14 H hardware block diagram 3 2 calibration 4 1 conf...

Страница 55: ...r requirement specifications A 6 programmable function interface See PFI programming examples NI resources B 1 PXI backplane clock 3 8 PXI star trigger bus See PXI_STAR 0 12 PXI star triggers front panel triggers as outputs 3 13 PXI trigger bus See PXI_TRIG 0 7 PXI triggers front panel triggers as outputs 3 13 PXI_CLK10 Active LED 3 4 clock generation 3 8 DDS phase lock 3 6 front panel triggers as...

Страница 56: ...ng 2 1 NI resources B 1 software programming choices overview 1 2 source possible sources table 3 12 signal 3 11 specifications CE compliance A 8 CLKIN characteristics A 1 CLKOUT characteristics A 2 DDS characteristics A 5 electromagnetic compatibility A 8 operating environment A 6 PFI 0 5 input characteristics A 3 output characteristics A 4 physical A 5 power requirements A 6 PXI trigger characte...

Страница 57: ...ensated oscillator See TCXO terminating signals with resistors note 3 12 threshold voltage 3 12 training and certification NI resources B 1 trigger bus See PXI_TRIG 0 7 troubleshooting NI resources B 1 U unpacking the device 1 2 V voltage thresholds programming 3 12 W Web resources B 1 ...

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