NI PXI-5411 User manual

PXI
NI PXI-6653 User Manual
Timing and Synchronization Module for PXI
NI PXI-6653 User Manual
November 2003 Edition
Part Number 370968A-01

Support
Worldwide Technical Support and Product Information
ni.com
National Instruments Corporate Headquarters
11500 North Mopac Expressway Austin, Texas 78759-3504 USA Tel: [phone]
Worldwide Offices
Australia 1800 300 800, Austria 43 0 662 45 79 90 0, Belgium 32 0 2 757 00 20, Brazil 55 11 3262 3599,
Canada (Calgary) 403 274 9391, Canada (Ottawa) 613 233 5949, Canada (Québec) 450 510 3055,
Canada (Toronto) 905 785 0085, Canada (Vancouver) 514 685 7530, China 86 21 6555 7838,
Czech Republic 420 224 235 774, Denmark 45 45 76 26 00, Finland 385 0 9 725 725 11,
France 33 0 1 48 14 24 24, Germany 49 0 89 741 31 30, Greece 30 2 10 42 96 427, India 91 80 51190000,
Israel 972 0 3 6393737, Italy 39 02 413091, Japan 81 3 5472 2970, Korea 82 02 3451 3400,
Malaysia 603 9131 0918, Mexico 001 800 010 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 7 095 783 68 51, Singapore 65 6226 5886, Slovenia 386 3 425 4200, South Africa 27 0 11 805 8197,
Spain 34 91 640 0085, Sweden 46 0 8 587 895 00, Switzerland 41 56 200 51 51, Taiwan 886 2 2528 7227,
Thailand 662 992 7519, United Kingdom 44 0 1635 523545
For further support information, refer to the Technical Support and Professional Services appendix. To comment
on the documentation, send email to [email protected].
©2003 National Instruments Corporation. All rights reserved.

Important Information
Warranty
The NI PXI-6653 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. National 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 National 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 APARTICULAR PURPOSE. CUSTOMER’SRIGHT 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 copyright 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™, IMAQ™, IVI™, LabVIEW™, MXI™, National Instruments™, NI™, ni.com™, NI-DAQ™, NI-VISA™, and RTSI™are trademarks of
National Instruments Corporation.
Product and company names mentioned herein are trademarks or trade names of their respective companies.
Patents
For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file
on your CD, or ni.com/patents.
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), UNANTICIPATED 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
Compliance with FCC/Canada Radio Frequency Interference
Regulations
Determining FCC Class
The Federal Communications Commission (FCC) has rules to protect wireless communications from interference. The FCC
places digital electronics into two classes. These classes are known as Class A (for use in industrial-commercial locations only)
or Class B (for use in residential or commercial locations). All National Instruments (NI) products are FCC Class A products.
Depending on where it is operated, this Class A 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.
All Class A products display a simple warning statement of one paragraph in length regarding interference and undesired
operation. The FCC rules have restrictions regarding the locations where FCC Class A products can be operated.
Consult the FCC Web site at 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 instructions
in this manual and the CE marking 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).
Changes or modifications not expressly approved by NI 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 is required to correct the interference
at their own expense.
Canadian Department of Communications
This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Compliance with EU Directives
Users in the European Union (EU) should refer to the Declaration of Conformity (DoC) for information* pertaining to the
CE marking. 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/hardref.nsf, search by model number or product line,
and click the appropriate link in the Certification column.
* The CE marking Declaration of Conformity contains important supplementary information and instructions for the user or
installer.

©National Instruments Corporation v NI PXI-6653 User Manual
Contents
About This Manual
Conventions ...................................................................................................................vii
National Instruments Documentation ............................................................................viii
Related Documentation..................................................................................................viii
Chapter 1
Introduction
What You Need to Get Started ......................................................................................1-1
Unpacking......................................................................................................................1-2
Software Programming Choices ....................................................................................1-2
Safety Information .........................................................................................................1-3
Chapter 2
Installing and Configuring
Installing the Software ...................................................................................................2-1
Installing the Hardware..................................................................................................2-1
Configuring the Module.................................................................................................2-2
Chapter 3
Hardware Overview
NI PXI-6653 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 OCXO..................................................................................3-8
Routing Signals..............................................................................................................3-9
Determining Sources and Destinations ...........................................................3-10
Using Front Panel PFIs As Inputs.....................................................3-11
Using Front Panel PFIs As Outputs ..................................................3-12
Using the PXI/RTSI Triggers ...........................................................3-13
Using the PXI Star Triggers..............................................................3-14

Contents
NI PXI-6653 User Manual vi ni.com
Choosing the Type of Routing ........................................................................ 3-14
Asynchronous Routing ..................................................................... 3-14
Synchronous Routing ....................................................................... 3-15
Generating a Single Pulse (Global Software Trigger) .................................... 3-17
Using the PXI_CLK10 PLL .......................................................................................... 3-18
Chapter 4
Calibration
Factory Calibration........................................................................................................ 4-1
OCXO 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

©National Instruments Corporation vii NI PXI-6653 User Manual
About This Manual
Thank you for purchasing the National Instruments NI PXI-6653 Timing
and Synchronization Module. The NI PXI-6653 enables you to pass
PXI timing and trigger signals between two or more PXI chassis. The
NI PXI-6653 can generate and route clock signals between devices in
multiple chassis, providing a method to synchronize multiple devices
in a multichassis PXI system.
This manual describes the electrical and mechanical aspects of the
NI PXI-6653 and contains information concerning its operation and
programming.
Conventions
The following conventions appear 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,
DIO<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 denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash. When this symbol is marked on
the product, refer to the Safety Information section of Chapter 1,
Introduction, for precautions to take.
bold Bold text denotes items that you must select or click in the software, such
as menu items and dialog box options. Bold text also denotes parameter
names and hardware labels.
italic 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.

About This Manual
NI PXI-6653 User Manual viii ni.com
monospace Text in this font denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.
NI PXI-6653 This phrase refers to the NI PXI-6653 module for the PXI bus.
National Instruments Documentation
The NI PXI-6653 User Manual is one piece of the documentation set for
your measurement system. You could have any of several other documents
describing your hardware and software. Use the documentation 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—Please refer to the readme.htm file on the
NI-Sync Driver and Examples CD, which ships with the device.
You can download NI documentation from ni.com/manuals.
Related Documentation
The following documents contain information that you might find helpful
as you read this manual:
•PICMG 2.0 R3.0, CompactPCI Core Specification, available from
PICMG at www.picmg.org
•PXI Specification, Revision 2.1, available from www.pxisa.org
•NI-VISA User Manual, available from ni.com/manuals
•NI-VISA Help, included with the NI-VISA software
•NI-Sync User Manual, available from ni.com/manuals

©National Instruments Corporation 1-1 NI PXI-6653 User Manual
1
Introduction
The NI PXI-6653 timing and triggering module enables you to pass
PXI timing signals between two or more PXI chassis. The NI PXI-6653
generates and routes clock signals between devices in multiple chassis,
providing a method for synchronizing multiple devices in a PXI system.
What You Need to Get Started
To set up and use the NI PXI-6653, you need the following items:
❑NI PXI-6653 Timing and Triggering Module
❑NI PXI-6653 User Manual
❑NI-VISA
❑NI-Sync Driver and Examples CD
❑One of the following software packages and documentation:
–LabVIEW
– LabWindows™/CVI™
– Microsoft Visual C++ (MSVC)
❑PXI chassis
❑PXI embedded controller or a desktop computer connected to the
PXI chassis using MXI-3 hardware
If you are using the NI PXI-6653 in a system to synchronize NI PXI-4472,
NI PXI-5112, NI PXI-5411, NI PXI-6115, or E Series DAQ modules, you
can refer to the NI-Sync User Manual, which you can find on the NI-Sync
Driver and Examples CD or download from ni.com/manuals.

Chapter 1 Introduction
NI PXI-6653 User Manual 1-2 ni.com
Unpacking
The NI PXI-6653 is shipped in an antistatic package to prevent electrostatic
damage to the module. Electrostatic discharge (ESD) can damage several
components on the module.
Caution Never touch the exposed pins of connectors.
To avoid such damage in handling the module, take the following
precautions:
• Ground yourself using a grounding strap or by touching a grounded
object.
• Touch the antistatic package to a metal part of the computer chassis
before removing the module from the package.
Remove the module from the package and inspect the module for loose
components 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 PXI-6653 in the antistatic envelope when not in use.
Software Programming Choices
When programming the NI PXI-6653, 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++.
LabVIEW features interactive graphics, a state-of-the-art interface, and
a powerful graphical programming language. The LabVIEW Data
Acquisition VI Library, a series of virtual instruments for using LabVIEW
with National Instruments DAQ hardware, is included with LabVIEW.
LabWindows/CVI is a complete ANSI C ADE that features an interactive
user interface, code generation tools, and the LabWindows/CVI Data
Acquisition and Easy I/O libraries.

Chapter 1 Introduction
©National Instruments Corporation 1-3 NI PXI-6653 User Manual
Safety Information
The following section contains important safety information that you must
follow when installing and using the product.
Do not operate the product in a manner not specified in this document.
Misuse of the product can result in a hazard. You can compromise the
safety protection built into the product if the product is damaged in any
way. If the product is damaged, return it to National Instruments for repair.
Do not substitute parts or modify the product except as described in this
document. Use the product only with the chassis, modules, accessories, and
cables specified in the installation instructions. You must have all covers
and filler panels installed during operation of the product.
Do not operate the product in an explosive atmosphere or where there may
be flammable gases or fumes. If you must operate the product in such an
environment, it must be in a suitably rated enclosure.
If you need to clean the product, use a soft, nonmetallic 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, nonconductive
pollution occurs. The pollution has no influence.
• Pollution Degree 2 means that only nonconductive pollution occurs in
most cases. Occasionally, however, a temporary conductivity caused
by condensation must be expected.
• Pollution Degree 3 means that conductive pollution occurs, or dry,
nonconductive pollution occurs that becomes conductive due to
condensation.
You must insulate signal connections for the maximum voltage for which
the product is rated. Do not exceed the maximum ratings for the product.
Do not install wiring while the product is live with electrical signals. Do not
remove or add connector blocks when power is connected to the system.
Avoid contact between your body and the connector block signal when hot
swapping modules. Remove power from signal lines before connecting
them to or disconnecting them from the product.

Chapter 1 Introduction
NI PXI-6653 User Manual 1-4 ni.com
Operate the product at or below the installation category1marked on the
hardware label. Measurement circuits are subjected to working voltages2
and transient stresses (overvoltage) from the circuit to which they are
connected during measurement or test. Installation categories establish
standard impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of installation
categories:
• Installation Category I is for measurements performed on circuits not
directly connected to the electrical distribution system referred to as
MAINS3voltage. This category is for measurements of voltages from
specially protected secondary circuits. Such voltage measurements
include signal levels, special equipment, limited-energy parts of
equipment, circuits powered by regulated low-voltage sources, and
electronics.
• Installation Category II is for measurements performed on circuits
directly connected to the electrical distribution system. This category
refers to local-level electrical distribution, such 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 equipment in fixed
installations, distribution boards, and circuit breakers. Other examples
are wiring, including cables, bus-bars, junction boxes, switches,
socket-outlets in the fixed installation, and stationary motors with
permanent connections to fixed installations.
• Installation Category IV is for measurements performed at the primary
electrical supply installation (<1,000 V). Examples include electricity
meters and measurements on primary overcurrent protection devices
and on ripple control units.
1 Installation categories, also referred to as measurement categories, are defined in electrical safety standard IEC 61010-1.
2 Working voltage is the highest rms value of an AC or DC voltage that can occur across any particular insulation.
3 MAINS is defined as a hazardous live electrical supply system that powers equipment. Suitably rated measuring circuits may
be connected to the MAINS for measuring purposes.

©National Instruments Corporation 2-1 NI PXI-6653 User Manual
2
Installing and Configuring
This chapter describes how to install the NI PXI-6653 hardware and
software and how to configure the device.
Installing the Software
Refer to the readme.htm file that accompanies the NI-Sync Driver and
Examples CD for software installation directions.
Note Be sure to install the driver software before installing the NI PXI-6653 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. Choose an available PXI slot in the PXI chassis.
Note The NI PXI-6653 is usually installed in Slot 2.
3. Remove the filler panel for the PXI slot you chose in step 2.
4. Ground yourself using a grounding strap or by touching a grounded
object. Follow the ESD protection precautions described in the
Unpacking section of Chapter 1, Introduction.
5. Insert the NI PXI-6653 into the PXI slot. Use the injector/ejector
handle to fully insert the module into the chassis.
6. Screw the front panel of the device to the front panel mounting rail of
the chassis.
7. Visually verify the installation. Make sure the module is not touching
other modules or components and is fully inserted into the slot.
8. Plug in and power on the chassis.
The NI PXI-6653 is now installed.

Chapter 2 Installing and Configuring
NI PXI-6653 User Manual 2-2 ni.com
Configuring the Module
The NI PXI-6653 is completely software configurable. The system
software automatically allocates all module resources.
The two LEDs on the front panel provide information about module status.
The NI PXI-6653 Front Panel section of Chapter 3, Hardware Overview,
describes the LEDs in greater detail. Refer to Figure 3-2, NI PXI-6653
Front Panel, for the parts locator diagram for the NI PXI-6653.

©National Instruments Corporation 3-1 NI PXI-6653 User Manual
3
Hardware Overview
This chapter presents an overview of the hardware functions of
the NI PXI-6653. Figure 3-1 provides a functional overview of
the NI PXI-6653 hardware.

Chapter 3 Hardware Overview
NI PXI-6653 User Manual 3-2 ni.com
Figure 3-1. Functional Overview of the NI PXI-6653
CLOCK and
TRIGGER
Routing
PCI Interface
PXIPCI
PXI_STAR<0..12>
PXI_TRIG<0..7>
CLKOUT
DDS
CLKIN AC Coupled
Clock Detector
PLL OCXO
PXI_CLK10_IN
OCXO
Calibration
DAC
OCXO
Clock
PXI_CLK10
DDS Clock
PFI<0..1>
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..5>
Threshold
DAC

Chapter 3 Hardware Overview
©National Instruments Corporation 3-3 NI PXI-6653 User Manual
NI PXI-6653 Front Panel
Figure 3-2 shows the connectors and LEDs on the front panel of the
NI PXI-6653.
Figure 3-2. NI PXI-6653 Front Panel
1 Access LED
2ActiveLED
3 CLKOUT Connector
4 CLKIN Connector
5 PFI <0..5> Connectors
NI PXI-6653
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

Chapter 3 Hardware Overview
NI PXI-6653 User Manual 3-4 ni.com
Access LED
The Access LED indicates the communication status of the NI PXI-6653.
Refer to Figure 3-2 for the location of the Access LED.
Table 3-1 summarizes what the Access LED colors represent.
Active LED
The Active LED can indicate an error or phase-locked loop (PLL) activity.
You can change the Active LED to amber, unless an error overrides the
selection. Refer to Figure 3-2 for the location of the Active LED.
Tip Changing the Active LED color to amber is 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 yet functional.
Green Driver has initialized the module.
Amber Module is being accessed. The Access LED
flashes amber for 50 ms when the module is
accessed.
Table 3-2. Active LED Color Quick Reference Table
Color
PXI_CLK10
Stopped PLL Error
User
Setting
PLL
Active
Red Yes Yes — —
Amber No No Yes —
Green No No No Yes
Off No No No No

Chapter 3 Hardware Overview
©National Instruments Corporation 3-5 NI PXI-6653 User Manual
Connectors
This section describes the connectors on the front panel of the
NI PXI-6653.
•CLKIN—Clock Input. This connector supplies the module with
a clock that can be programmatically routed to the onboard PLL
for use as a reference or routed directly to the PXI backplane
(PXI_CLK10_IN) for distribution to the other modules in the chassis.
•CLKOUT—Clock Output. This connector is used to source a clock
that can programmatically be routed from the oven-controlled crystal
oscillator (OCXO), Direct Digital Synthesis (DDS), or backplane
clock (PXI_CLK10).
•PFI <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 these
connections on the NI PXI-6653 front panel.
Caution Connections that exceed any of the maximum ratings of input or output signals
on the NI PXI-6653 can damage the module and the computer. NI is not liable for any
damage resulting from such signal connections.
Hardware Features
The NI PXI-6653 performs two broad functions:
• Generating clock and trigger signals
• Routing internally or externally generated signals from one location
to another
Table 3-3 outlines the function and direction of the signals that are
discussed in detail in the remainder of this chapter.

Chapter 3 Hardware Overview
NI PXI-6653 User Manual 3-6 ni.com
Table 3-3. Signal Descriptions
Signal Name Direction Description
PXI_CLK10_IN Out This is a signal that can replace the native
10 MHz oscillator on the PXI backplane.
PXI_CLK10_IN may originate from the onboard
OCXO or from an external source.
PXI_CLK10 In This signal is the PXI 10 MHz backplane clock.
By default, this signal is the output of the native
10 MHz oscillator in the chassis. An
NI PXI-6653 in Slot 2 can replace this signal
with PXI_CLK10_IN.
OCXO Clock Out This is the output of the 10 MHz OCXO. The
OCXO is an extremely stable and accurate
frequency source.
CLKIN In CLKIN is a signal connected to the SMB input
pin of the same name. CLKIN can serve as
PXI_CLK10_IN or be used as a phase lock
reference for the OCXO.
CLKOUT Out CLKOUT is the signal on the SMB output pin
of the same name. Either the OCXO clock or
PXI_CLK10 may be routed to this location.
DDS Clock Out This is the output of the NI PXI-6653 DDS. The
DDS frequency can be programmed with fine
granularity from 1 Hz to 80 MHz. The DDS chip
automatically phase-locks to PXI_CLK10.
PXI_STAR <0..12> In/Out The PXI star trigger bus connects Slot 2 to
Slot <3..15> in a star configuration. The
electrical paths of each star line are closely
matched to minimize intermodule skew. An
NI PXI-6653 in Slot 2 can route signals to
Slots <3..15> using the star trigger bus.