NI PXIe-6674T User manual

PXI Express
NI PXIe-6674T User Manual
Timing and Synchronization Module for PXI Express
NI PXIe-6674T User Manual
May 2015
373089C-01

Support
Worldwide Technical Support and Product Information
ni.com
Worldwide Offices
Visit ni.com/niglobal to access the branch office websites, which provide up-to-date
contact information, support phone numbers, email addresses, and current events.
National Instruments Corporate Headquarters
11500 North Mopac Expressway Austin, Texas 78759-3504 USA Tel: [phone]
For further support information, refer to the NI Services appendix. To comment on National
Instruments documentation, refer to the National Instruments website at ni.com/info and
enter the Info Code feedback.
©2010–2015 National Instruments. All rights reserved.

Legal Information
Limited Warranty
This document is provided ‘as is’ and is subject to being changed, without notice, in future editions. For the latest version,
refer to ni.com/manuals. NI reviews this document carefully for technical accuracy; however, NI MAKES NO EXPRESS
OR IMPLIED WARRANTIES AS TO THE ACCURACY OF THE INFORMATION CONTAINED HEREIN AND
SHALL NOT BE LIABLE FOR ANY ERRORS.
NI warrants that its hardware products will be free of defects in materials and workmanship that cause the product to fail to
substantially conform to the applicable NI published specifications for one (1) year from the date of invoice.
For a period of ninety (90) days from the date of invoice, NI warrants that (i) its software products will perform substantially
in accordance with the applicable documentation provided with the software and (ii) the software media will be free from
defects in materials and workmanship.
If NI receives notice of a defect or non-conformance during the applicable warranty period, NI will, in its discretion: (i) repair
or replace the affected product, or (ii) refund the fees paid for the affected product. Repaired or replaced Hardware will be
warranted for the remainder of the original warranty period or ninety (90) days, whichever is longer. If NI elects to repair or
replace the product, NI may use new or refurbished parts or products that are equivalent to new in performance and reliability
and are at least functionally equivalent to the original part or product.
You must obtain an RMA number from NI before returning any product to NI. NI reserves the right to charge a fee for
examining and testing Hardware not covered by the Limited Warranty.
This Limited Warranty does not apply if the defect of the product resulted from improper or inadequate maintenance,
installation, repair, or calibration (performed by a party other than NI); unauthorized modification; improper environment;
use of an improper hardware or software key; improper use or operation outside of the specification for the product; improper
voltages; accident, abuse, or neglect; or a hazard such as lightning, flood, or other act of nature.
THE REMEDIES SET FORTH ABOVE ARE EXCLUSIVE AND THE CUSTOMER’S SOLE REMEDIES, AND SHALL
APPLY EVEN IF SUCH REMEDIES FAIL OF THEIR ESSENTIAL PURPOSE.
EXCEPT AS EXPRESSLY SET FORTH HEREIN, PRODUCTS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF
ANY KIND AND NI DISCLAIMS ALL WARRANTIES, EXPRESSED OR IMPLIED, WITH RESPECT TO THE
PRODUCTS, INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, TITLE OR NON-INFRINGEMENT, AND ANY WARRANTIES THAT MAY ARISE FROM
USAGE OF TRADE OR COURSE OF DEALING. NI DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
REPRESENTATIONS REGARDING THE USE OF OR THE RESULTS OF THE USE OF THE PRODUCTS IN TERMS
OF CORRECTNESS, ACCURACY, RELIABILITY, OR OTHERWISE. NI DOES NOT WARRANT THAT THE
OPERATION OF THE PRODUCTS WILL BE UNINTERRUPTED OR ERROR FREE.
In the event that you and NI have a separate signed written agreement with warranty terms covering the products, then the
warranty terms in the separate agreement shall 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.
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 software or other materials
belonging to others, you may use NI software only to reproduce materials that you may reproduce in accordance with the
terms of any applicable license or other legal restriction.
End-User License Agreements and Third-Party Legal Notices
You can find end-user license agreements (EULAs) and third-party legal notices in the following locations:
• Notices are located in the <National Instruments>\_Legal Information and <National Instruments>
directories.
• EULAs are located in the <National Instruments>\Shared\MDF\Legal\license directory.
•Review
<National Instruments>\_Legal Information.txt for information on including legal information in
installers built with NI products.
U.S. Government Restricted Rights
If you are an agency, department, or other entity of the United States Government (“Government”), the use, duplication,
reproduction, release, modification, disclosure or transfer of the technical data included in this manual is governed by the
Restricted Rights provisions under Federal Acquisition Regulation 52.227-14 for civilian agencies and Defense Federal
Acquisition Regulation Supplement Section 252.227-7014 and 252.227-7015 for military agencies.
Trademarks
Refer to the NI Trademarks and Logo Guidelines at ni.com/trademarks for more information on National Instruments
trademarks.
ARM, Keil, and µVision are trademarks or registered of ARM Ltd or its subsidiaries.
LEGO, the LEGO logo, WEDO, and MINDSTORMS are trademarks of the LEGO Group.
TETRIX by Pitsco is a trademark of Pitsco, Inc.
FIELDBUS FOUNDATION™and FOUNDATION™are trademarks of the Fieldbus Foundation.

EtherCAT®is a registered trademark of and licensed by Beckhoff Automation GmbH.
CANopen®is a registered Community Trademark of CAN in Automation e.V.
DeviceNet™and EtherNet/IP™are trademarks of ODVA.
Go!, SensorDAQ, and Vernier are registered trademarks of Vernier Software & Technology. Vernier Software & Technology
and vernier.com are trademarks or trade dress.
Xilinx is the registered trademark of Xilinx, Inc.
Taptite and Trilobular are registered trademarks of Research Engineering & Manufacturing Inc.
FireWire®is the registered trademark of Apple Inc.
Linux®is the registered trademark of Linus Torvalds in the U.S. and other countries.
Handle Graphics®, MATLAB®, Real-Time Workshop®, Simulink®, Stateflow®, and xPC TargetBox®are registered
trademarks, and TargetBox™and Target Language Compiler™are trademarks of The MathWorks, Inc.
Tektronix®, Tek, and Tektronix, Enabling Technology are registered trademarks of Tektronix, Inc.
The Bluetooth®word mark is a registered trademark owned by the Bluetooth SIG, Inc.
The ExpressCard™word mark and logos are owned by PCMCIA and any use of such marks by National Instruments is under
license.
The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft
Corporation in the United States and other countries.
Other product and company names mentioned herein are trademarks or trade names of their respective companies.
Members of the National Instruments Alliance Partner Program are business entities independent from National Instruments
and have no agency, partnership, or joint-venture relationship with National Instruments.
Patents
For patents covering National Instruments products/technology, refer to the appropriate location: Help»Patents in your
software, the patents.txt file on your media, or the National Instruments Patent Notice at ni.com/patents.
Export Compliance Information
Refer to the Export Compliance Information at ni.com/legal/export-compliance for the National Instruments global
trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/export data.
WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS
YOU ARE ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY AND
RELIABILITY OF THE PRODUCTS WHENEVER THE PRODUCTS ARE INCORPORATED IN YOUR SYSTEM OR
APPLICATION, INCLUDING THE APPROPRIATE DESIGN, PROCESS, AND SAFETY LEVEL OF SUCH SYSTEM
OR APPLICATION.
PRODUCTS ARE NOT DESIGNED, MANUFACTURED, OR TESTED FOR USE IN LIFE OR SAFETY CRITICAL
SYSTEMS, HAZARDOUS ENVIRONMENTS OR ANY OTHER ENVIRONMENTS REQUIRING FAIL-SAFE
PERFORMANCE, INCLUDING IN THE OPERATION OF NUCLEAR FACILITIES; AIRCRAFT NAVIGATION; AIR
TRAFFIC CONTROL SYSTEMS; LIFE SAVING OR LIFE SUSTAINING SYSTEMS OR SUCH OTHER MEDICAL
DEVICES; OR ANY OTHER APPLICATION IN WHICH THE FAILURE OF THE PRODUCT OR SERVICE COULD
LEAD TO DEATH, PERSONAL INJURY, SEVERE PROPERTY DAMAGE OR ENVIRONMENTAL HARM
(COLLECTIVELY, “HIGH-RISK USES”). FURTHER, PRUDENT STEPS MUST BE TAKEN TO PROTECT AGAINST
FAILURES, INCLUDING PROVIDING BACK-UP AND SHUT-DOWN MECHANISMS. NI EXPRESSLY DISCLAIMS
ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS OF THE PRODUCTS OR SERVICES FOR HIGH-RISK
USES.

Compliance
Electromagnetic Compatibility Information
This hardware has been tested and found to comply with the applicable regulatory requirements and limits
for electromagnetic compatibility (EMC) as indicated in the hardware’s Declaration of Conformity (DoC)1.
These requirements and limits are designed to provide reasonable protection against harmful interference
when the hardware is operated in the intended electromagnetic environment. In special cases, for example
when either highly sensitive or noisy hardware is being used in close proximity, additional mitigation
measures may have to be employed to minimize the potential for electromagnetic interference.
While this hardware is compliant with the applicable regulatory EMC requirements, there is no guarantee
that interference will not occur in a particular installation. To minimize the potential for the hardware to
cause interference to radio and television reception or to experience unacceptable performance degradation,
install and use this hardware in strict accordance with the instructions in the hardware documentation and
the DoC1.
If this hardware does cause interference with licensed radio communications services or other nearby
electronics, which can be determined by turning the hardware off and on, you are encouraged to try to correct
the interference by one or more of the following measures:
• Reorient the antenna of the receiver (the device suffering interference).
• Relocate the transmitter (the device generating interference) with respect to the receiver.
• Plug the transmitter into a different outlet so that the transmitter and the receiver are on different branch
circuits.
Some hardware may require the use of a metal, shielded enclosure (windowless version) to meet the EMC
requirements for special EMC environments such as, for marine use or in heavy industrial areas. Refer to
the hardware’s user documentation and the DoC1for product installation requirements.
When the hardware is connected to a test object or to test leads, the system may become more sensitive to
disturbances or may cause interference in the local electromagnetic environment.
Operation of this hardware in a residential area is likely to cause harmful interference. Users are required to
correct the interference at their own expense or cease operation of the hardware.
Changes or modifications not expressly approved by National Instruments could void the user’s right to
operate the hardware under the local regulatory rules.
1 The Declaration of Conformity (DoC) contains important EMC compliance information and instructions
for the user or installer. 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.

© National Instruments |vii
Contents
About This Manual
National Instruments Documentation............................................................................... ix
Related Documentation .................................................................................................... ix
Chapter 1
Introduction
What You Need to Get Started ......................................................................................... 1-1
Unpacking......................................................................................................................... 1-2
Software Programming Choices....................................................................................... 1-2
Safety Information ............................................................................................................ 1-2
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 PXIe-6674T Front Panel ............................................................................................. 3-3
Access LED .............................................................................................................. 3-4
Active LED............................................................................................................... 3-5
Connectors ................................................................................................................ 3-5
Hardware Features............................................................................................................ 3-6
Generating and Routing Clocks........................................................................................ 3-8
Clock Generation...................................................................................................... 3-8
PXI_CLK10 and PXIe_CLK100.............................................................................. 3-9
Using PXI_CLK10_IN ..................................................................................... 3-10
PXIe_DSTARA, PXIe_DSTARB, and PXIe_DSTARC ................................. 3-11
Routing Signals.................................................................................................................3-16
Determining Sources and Destinations..................................................................... 3-17
Using Front Panel PFIs as Single Ended Inputs ............................................... 3-20
Using Front Panel PFIs as Single Ended Outputs ............................................ 3-20
Using Front Panel PFIs for LVDS Triggers ..................................................... 3-21
Using the PXI Triggers..................................................................................... 3-22
Using the PXI Star Triggers ............................................................................. 3-23
Using the PXIe_DSTARB and PXIe_DSTARC Triggers ....................................... 3-23
Choosing the Type of Routing.................................................................................. 3-24
Asynchronous Routing ..................................................................................... 3-24
Synchronous Routing ....................................................................................... 3-25

Contents
viii |ni.com
Chapter 4
Calibration
Factory Calibration ........................................................................................................... 4-1
OCXO Frequency .....................................................................................................4-1
PXI_CLK10 Phase.................................................................................................... 4-1
Additional Information .....................................................................................................4-1
Appendix A
Specifications
Appendix B
NI Services
Glossary
Index

© National Instruments |ix
About This Manual
Thank you for purchasing the National Instruments NI PXIe-6674T Timing and Synchronization
Module. The NI PXIe-6674T enables you to pass PXI timing and trigger signals between
PXI Express chassis. The NI PXIe-6674T can generate and route clock signals between devices
in multiple chassis, providing a method to synchronize multiple devices in a multichassis
PXI Express system.
This manual describes the electrical and mechanical aspects of the NI PXIe-6674T and contains
information concerning its operation and programming.
National Instruments Documentation
The NI PXIe-6674T 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—Refer to the NI-Sync User Manual, available at ni.com/
manuals.
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
•NI PXIe-6674T Calibration Procedure, available from ni.com/manuals

© National Instruments |1-1
1
Introduction
The NI PXIe-6674T timing and synchronization module enables you to share clock and triggers
between modules in a PXI Express chassis and other PXI chassis or non-PXI systems. The
NI PXIe-6674T module generates and routes clock signals between devices in multiple chassis,
providing a method for synchronizing multiple devices in a PXI Express system. It also features
a precision OCXO for improving the stability and accuracy of the PXI Express backplane
reference clocks.
What You Need to Get Started
To set up and use the NI PXIe-6674T, you need the following items:
NI PXIe-6674T Timing and Synchronization Module
NI PXIe-6674T User Manual
NI-Sync CD
One of the following software packages and documentation:
–LabVIEW
– LabWindows™/CVI™
– Microsoft Visual C++ (MSVC)
PXI EMC filler panels, National Instruments part number 778700-01
PXI Express chassis
PXI Express embedded controller or a desktop computer connected to the
PXI Express chassis using MXI-Express hardware
The NI-Sync User Manual offers more detailed information on the software used to program the
NI PXIe-6674T. You can find this manual on the NI-Sync CD or download it from ni.com/
manuals.

1-2 |ni.com
Chapter 1 Introduction
Unpacking
The NI PXIe-6674T is shipped in an antistatic package to prevent electrostatic damage to the
module. Electrostatic discharge (ESD) can damage 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 PXIe-6674T in the antistatic envelope when not in use.
Software Programming Choices
When programming the NI PXIe-6674T, 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.
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.

© National Instruments |1-3
NI PXIe-6674T User Manual
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.
Operate the product at or below the measurement category1marked on the hardware label.
Measurement circuits are subjected to working voltages2and transient stresses (overvoltage)
from the circuit to which they are connected during measurement or test. Measurement
categories establish standard impulse withstand voltage levels that commonly occur in electrical
distribution systems. The following is a description of measurement categories:
• Measurement 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 hardware, limited-energy parts of hardware,
circuits powered by regulated low-voltage sources, and electronics.
• Measurement Category II is for measurements performed on circuits directly connected to
the electrical distribution system (MAINS3). This category refers to local-level electrical
distribution, such as that provided by a standard wall outlet (for example, 115 AC voltage
1 Measurement categories, also referred to as overvoltage or installation categories, are defined in electrical
safety standard IEC 61010-1 and IEC 60664-1.
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 hardware. Suitably rated
measuring circuits may be connected to the MAINS for measuring purposes.

1-4 |ni.com
Chapter 1 Introduction
for U.S. or 230 AC voltage for Europe). Examples of Measurement Category II are
measurements performed on household appliances, portable tools, and similar hardware.
• Measurement Category III is for measurements performed in the building installation at the
distribution level. This category refers to measurements on hard-wired hardware such as
hardware 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.
• Measurement Category IV is for measurements performed at the primary electrical supply
installation typically outside buildings. Examples include electricity meters and
measurements on primary overcurrent protection devices and on ripple control units.

© National Instruments |2-1
2
Installing and Configuring
This chapter describes how to install the NI PXIe-6674T hardware and software and how to
configure the device.
Installing the Software
Refer to the readme.htm file that accompanies the NI-Sync CD for software installation
directions.
Note Be sure to install the driver software before installing the NI PXIe-6674T
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 for your PXI Express chassis. It is identified by the glyph
shown in Figure 2-1.
Figure 2-1. System Timing Slot Indicator Glyph
3. Remove the filler panel for the system timing slot, if applicable.
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. Carefully insert the NI PXIe-6674T into the system timing slot making sure to not scrape
the module on any adjacent modules. 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. If adjacent slots are not populated, use EMC filler panels to cover the opening.

2-2 |ni.com
Chapter 2 Installing and Configuring
Caution To ensure the specified EMC performance, you must install PXI EMC
filler panels, National Instruments part number 778700-01, in all open chassis slots.
8. Visually verify the installation. Ensure that the module is fully inserted into the slot.
9. Plug in and power on the chassis.
The NI PXIe-6674T is now installed.
Configuring the Module
The NI PXIe-6674T 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 front panel
description sections of Chapter 3, Hardware Overview, describe the LEDs in greater detail.

© National Instruments |3-1
3
Hardware Overview
This chapter presents an overview of the hardware functions of the NI PXIe-6674T. Figure 3-1
provides a functional overview of the NI PXIe-6674T hardware.

3-2 |ni.com
Chapter 3 Hardware Overview
Figure 3-1. Functional Overview of the NI PXIe-6674T
CLOCK and
TRIGGER
Routing
PCI Express
Interface
PCI Express
PXI_STAR<0..16>
PXI_TRIG<0..7>
CLKOUT
Clock
Generation
CLKIN AC Coupled
Clock Detector
PLL OCXO
PXI_CLK10_IN
OCXO
Calibration
DAC
OCXO
Clock
PXI_CLK10
Clock Generation
PXIe_DSTARA
Routing
PXI Express
PXIe_CLK100
PXIe_DSTA R A
<0..16>
OCXO
CLK10
CLK100
PXIe_DSTA R C
<0..16>
PXIe_DSTA R B
<0..16>
PFI 0
Threshold
DAC
PFI 0
Driver/
Comparator
Driver/
Comparator
PFI 1
Threshold
DAC
LVDSDriver/
Receiver
PFI 1
PFI 2
Threshold
DAC
PFI 2
Driver/
Comparator
Driver/
Comparator
PFI 3
Threshold
DAC
LVDSDriver/
Receiver
PFI 3
PFI 4
Threshold
DAC
PFI 4
Driver/
Comparator
Driver/
Comparator
PFI 5
Threshold
DAC
LVDSDriver/
Receiver
PFI 5
PFI_LVDS
<0..2>
PFI<0..5>
CLKIN

© National Instruments |3-3
NI PXIe-6674T User Manual
NI PXIe-6674T Front Panel
Figure 3-2 shows the connectors and LEDs on the front panel of the NI PXIe-6674T.
Figure 3-2. NI PXIe-6674T Front Panel
1 Access LED
2 Active LED
3 CLKOUT Connector
4 PFI<0..5> Connectors
5 CLKIN Connector
1 2
3
5
4
Timing Module
NI PXIe-6674T
PFI 0/
LVDS
0-
PFI 1/
LVDS
0+
PFI 2/
LVDS
1-
PFI 3/
LVDS
1+
PFI 5/
LVDS
2+
PFI 4/
LVDS
2-
CLK
OUT
CLK
IN

3-4 |ni.com
Chapter 3 Hardware Overview
Access LED
The Access LED indicates the communication status of the NI PXIe-6674T. Refer to Figure 3-2
for the location of the Access LED.
Table 3-1 summarizes what the Access LED colors represent.
Caution If the Access LED is observed to be blinking red, the module has detected
an over-temperature condition. Continued use of the NI PXIe-6674T in this condition
is not recommended as product reliability may become comprised. Since several
common problems can cause an over-temperature condition, please investigate the
following:
• Check that all chassis covers, filler panels, and/or slot blockers are installed.
• Make sure that the chassis fan speed is set to the highest setting.
• If applicable, check that the chassis fan air intake is not blocked and that the fan
filters are clean.
• Make sure that the ambient temperature around the chassis isn't above the rated
temperature specifications. If so, move the chassis to a cooler ambient
temperature location.
Caution If the Access LED is observed to be solid red, a hardware failure has been
detected that may impact the performance of the NI PXIe-6674T. Contact National
Instruments for support.
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.
Blinking Red Module has detected an over-temperature condition.
Solid Red A hardware error has been detected.

© National Instruments |3-5
NI PXIe-6674T User Manual
Active LED
The Active LED indicates 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 summarizes what the Active LED colors represent.
Connectors
This section describes the connectors on the front panel of the NI PXIe-6674T.
•CLKIN—AC coupled, 50 Ωclock input. CLKIN can be routed directly to
PXI_CLK10_IN, to the 10 MHz PLL, to PXIe_DSTARA, or to the FPGA for use as a
synchronization clock.
•CLKOUT—AC coupled clock output. CLKOUT can be sourced from the OCXO,
PXI-CLK10, Clock Generation, or from the PXIe_DSTARA network.
•PFI<0..5>/PFI_LVDS<0..2>—Programmable Function Interface which can be
individually configured for either single ended operation or LVDS operation. In LVDS
mode, the connectors are paired and can be programmatically set as either inputs or outputs,
but not both simultaneously.
Refer to Figure 3-2 for a diagram showing the locations of these connections on the
NI PXIe-6674T front panel.
Caution Connections that exceed any of the maximum ratings of input or output
signals on the NI PXIe-6674T can damage the module and the computer. NI is not
liable for any damage resulting from such signal connections.
Table 3-2. Active LED Color Indication
Active LED Color Status
Off The 10 MHz PLL is not in use and no errors are present.
Green The 10 MHz PLL is active and locked.
Solid Amber The user can set the Active LED to amber through software.
Solid Red 10 MHz PLL is attempting to lock to the reference supplied on
CLKIN.

3-6 |ni.com
Chapter 3 Hardware Overview
Hardware Features
The NI PXIe-6674T 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 discussed in detail in the remainder
of this chapter.
Table 3-3. Signal Descriptions
Signal Name Direction Description
PXI_CLK10_IN Out
(to chassis)
This is a signal that can be used to provide the
backplane with a reference 10 MHz signal from the
system timing slot. When a 10 MHz signal is
connected to PXI_CLK10_IN, the PXI Express
chassis is required to derive PXI_CLK10 and
PXIe_CLK100 from this reference. Refer to the user
manual for your PXI Express chassis for more
information on how it uses PXI_CLK10_IN.
PXI_CLK10 In
(from
chassis)
This signal is the PXI 10 MHz backplane clock. This
signal is the output of the native 100 MHz oscillator
in the chassis divided by ten.
PXIe_CLK100 In
(from
chassis)
This signal is the PXI Express 100 MHz backplane
clock. PXIe_CLK100 offers tighter slot to slot timing
than PXI_CLK10.
OCXO Clock Out
(internal)
This is the output of the 10 MHz OCXO. The OCXO
is an extremely stable and accurate frequency source.
CLKIN In
(from front
panel)
CLKIN is the signal connected to the SMA input
connector of the same name. CLKIN can be routed
directly to PXI_CLK10_IN, to the 10 MHz PLL, to
PXIe_DSTARA, or to the FPGA.
CLKOUT Out
(to front
panel)
CLKOUT is the signal on the SMA output connector
of the same name. CLKOUT can be sourced from the
OCXO, PXI_CLK10, Clock Generation, or from the
PXIe_DSTARA network.