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National Instruments Corporate Headquarters
6504 Bridge Point Parkway Austin, Texas 78730-5039 USA Tel: 512 794 0100
Important Information
Warranty
The PCI-6110E/6111E boards are 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 workm anship, f or a period of 90 days fr om date of ship ment, as evid enced
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 p arts whic h are co vered by w arran ty.
National Instruments believes that the information in this manual 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 Instrum ents be liable for
any damages arising out of or related to this document or the information contained in it.
XCEPT AS SPECIFIED HEREIN
E
SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
USTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL
C
NSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER
I
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
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.
ATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND
, N
.
ATIONAL INSTRUMENTS
. N
. This limitation of the liability of National
Copyright
Under the copyright laws, this publ ication may not be r eproduced or tr ansmitted in any form, electron ic 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
ComponentWorks™, CVI™, DAQ-STC™, LabVIEW™, Measure™, MITE™, NI-DAQ™, NI-PGIA™, RTSI™,
SCXI™, and VirtualBench™ are trademarks of National Instruments Corporation.
Product and company names listed are trademarks or trade names of their respective companies.
WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS
National Instruments products are not designed with components and testing intended to ensure a level of reliability
suitable for use in treatment and diagnosis of humans. Applications of National Instruments products involving
medical or clinical treatment can create a potential for accidental injury caused by product failure, or by errors on the
part of the user or application designer. Any use or application of National Instruments products for or involving
medical or clinical treatment must be performed by properly trained and qualified medical personnel, and al l traditional
medical safeguards, equipment, and procedures that are appropriate in the particular situation to prevent serious injury
or death should always continue to be used when National Instruments products are being used. National Instruments
products are NOT intended to be a substitute for any form of esta blishe d process, proced ure, or equipm ent used to
monitor or safeguard human health and safety in medical or clinical treatment.
About This Manual
Organization of This Manual........................................................................................xi
Conventions Used in This Manual................................................................................xii
National Instruments Documentation.... .................................. .....................................xiii
Related Documentation........................................... ......................................................xiv
National Instruments CorporationixPCI-6110E/6111E User Manual
This manual describes the electrical and mechanical aspects of the
611XE family of boards and contains information concerning their
operation and programming.
The 611X E family of boards includes:
• PCI-6110E
• PCI-6111E
Your 611X E board is a high-performance multifunction analog, digital,
and timing I/O board for PCI bus computers. Supported functions
include analog input, analog output, digital I/O, and timingI/O.
Organization of This Manual
PCI-6110E/6111E User Manual
The
• Chapter1,
you need to get started, describes the optional software and optiona l
equipment, and explains how to unpack your 611X E board.
• Chapter2,
and configure your 611X E board.
• Chapter3,
hardware functions on your 611X E board.
• Chapter4,
output signal connections to your 611X E board via the board I/O
connector.
National Instruments CorporationxiPCI-6110E/6111E User Manual
About This Manual
• AppendixC,
asked questions and their answers relating to usage and special
features of your 611X E board.
• AppendixD,
use to request help from National Instruments or to comment on
ourproducts.
•The
•The
Glossary
used in this manual, including acronyms, abbreviations, defini tions
metric prefixes, mnemonics, and symbols.
Index
including the page where you can find the topic.
Common Questions
Customer Communication
contains an alphabetical list and description of terms
alphabetically lists topics covered in this manual,
, contains a list of commonly
, contains forms you can
Conventions Used in This Manual
The following conventions are used in this manual.
<> Angle brackets enclose the name of a key on the keyboard (for example,
<option>). Angle brackets containing numbers separated by an ellipsis
represent a range of values associated with a bit or signal name
(forexample, DIO<3..0>).
611X E This refers to either the PCI-6110E or PCI-6111E board.
This icon to the left of bold italiciz ed text de notes a n ote, which al erts
you to important information.
!
bold Bold text denotes the names of menus, menu items, parameters, dialog
bold italic Bold italic text denotes a note, caution, or warning.
italic
Macintosh Macintosh refers to all Macintosh OS computers with PCI bus, unless
PCI-6110E/6111E User Manualxii
This icon to the left of bold italiciz ed text de notes a ca ution, wh ich
advises you of precautions to take to avoid injury, data los s, or a
systemcrash.
boxes, dialog box buttons or options, icons, windows, Win dows 95 tabs,
or LEDs.
Italic text denotes emphasis, a cross reference, or an introduction to a
key concept. This font also denotes text from which you supply the
appropriate word or value, as in Windows 3.x.
monospaceText in this font denotes text or characters that you should literally enter
from the keyboard, sections of code, programming examples, and
syntax examples. This font also is used for the proper names of disk
drives, paths, directories, programs, subprograms, subroutines, device
names, functions, operations, variables, filenames, and extensions, and
for statements and comments taken from program code.
NI-DAQNI-DAQ refers to the NI-DAQ driver software for Macintosh or
PC compatible computers unless otherwise noted.
PCRefers to all PC AT series computers with PCI bus unless otherwise
noted.
SCXISCXI stands for Signal Conditioning eXentsions for Instrumentation
and is a National Instruments product line designed to perform
front-end signal conditioning for National instruments plug-in DAQ
boards.
National Instruments Documentation
PCI-6110E/6111E User Manual
The
set for your DAQ system. You could have any of several types of
documentation depending on the hardware and software in your system.
Use the documentation you have as follows:
Getting Started with SCXI
•
manual you should read. It gives an overview of the SCXI system
and contains the most commonly needed information for the
modules, chassis, and software.
•Your SCXI hardware user manuals—If you are using SCXI, read
these manuals next for detailed information about signal
connections and module configuration. They also explai n in greater
detail how the module works and contain application hints.
•Your DAQ hardware documentation—This documentation has
detailed information about the DAQ h ardware that plugs in to or is
connected to your computer. Use this documentation for hardware
installation and configuration instructions, specification
information about your DAQ hardware, and application hints.
•Software documentation—You may have both application software
and NI-DAQ software documentation. National Instruments
application software includes ComponentWorks, LabVIEW,
LabWindows/CVI, Measure, and VirtualBench. After you set up
your hardware system, use either your application software
National Instruments CorporationxiiiPCI-6110E/6111E User Manual
About This Manual
documentation or the NI-DAQ documentation to help you write
your application. If you have a large, complicated system, it is
worthwhile to look through the software documentation before you
configure your hardware.
• Accessory installation guides or manuals—If you are using
accessory products, read the terminal block and cable assembly
installation guides. They explain how to physically connect the
relevant pieces of the system. Consult these guides when you are
making your connections.
• SCXI chassis manuals—If you are using SCXI, read these manuals
for maintenance information on the chassis and installation
instructions.
Related Documentation
The following documents contain information you may find helpful:
• DAQ-STC Technical Reference Manual
• National Instruments Application Note 025,
Considerations for Analog Signals
• PCI Local Bus Specification Revision 2.0
Field Wiring and Noise
Customer Communication
National Instruments wants to receive your comments on our products
and manuals. We are interested in the applications you develop with our
products, and we want to help if you have problems with them. To make
it easy for you to contact us, this manual contains comment and
configuration forms for you to complete. These forms are in
This chapter describes your 611X E board, lists what you need to get
started, describes the optional software and optional equipment, and
explains how to unpack your 611X E board.
About the 611X E Boards
Thank you for buying a National Instruments PCI-6110E/6111E
board. Your 611X E board is a completely Plug and Play, multifunction
analog, digital, and timing I/O board for PCI bus computers. The
611XE board features a 12-bit ADC per channel with four or two
simultaneously sampling analog inputs, 16-bit DACs with voltage
outputs, eight lines of TTL-compatible digital I/O, and two 24-bit
counter/timers for timing I/O. Because the 611X E board has no DIP
switches, jumpers, or potentiometers, it is easily software-configured
and calibrated.
The 611X E board is a completely switchless and jumperless data
acquisition (DAQ) board for the PCI bus. This feature is made possible
by the National Instruments MITE bus interface chip that connects the
board to the PCI I/O bus. The MITE implements the PCI Local Bus
Specification so that the interrupts and base memory addresses are all
software configured.
1
The 611X E board uses the National Instruments DAQ-STC system
timing controller for time-related functions. The DAQ-STC consists
of three timing groups that control analog input, analog output, and
general-purpose counter/timer functions. These groups include a total
of seven 24-bit and three 16-bit counters and a maximum timing
resolution of 50 ns. The DAQ-STC makes possible such applications as
buffered pulse generation, equivalent time sampling, and seamlessly
changing the sampling rate.
Often with DAQ boards, you cannot easily synchronize several
measurement functions to a common trigger or timing event. The
611XE board has the Real-Time System Integration (RTSI) bus to
solve this problem. The RTSI bus consists of our RTSI bus interface
National Instruments Corporation1-1PCI-6110E/6111E User Manual
Chapter 1Introduction
and a ribbon cable to route timing and trigger signals between several
functions on as many as five DAQ boards in your computer.
Detailed specifications of the 611X E board are in Appendix A,
Specifications
.
What You Need to Get Started
To set up and use the 611X E board, you will need the following:
❑ Either the PCI-6110E or PCI-6111E board
PCI-6110E/6111E User Manual
❑
❑ One of the following software packages and documentation:
ComponentWorks
LabVIEW for Macintosh
LabVIEW for Windows
LabWindows/CVI for Windows
Measure
NI-DAQ for PC Compatibles
VirtualBench
❑ Your computer
Software Programming Choices
You have several options to choose from when programming your
National Instruments DAQ and SCXI hardware. You can use National
Instruments application software, NI-DAQ, or register-level
programming.
National Instruments Application Software
ComponentWorks contains tools for data acquisition and instrument
control built on NI-DAQ driver software. ComponentWorks provides
a higher-level programming interface for building virtual instruments
through standard OLE controls and DLLs. With Compon entWorks, you
can use all of the configuration tools, resource management utilities,
and interactive control utilities included with NI-DAQ.
LabVIEW features interactive graphics, a state-of-the-art user
interface, and a powerful graphical programming language. The
LabVIEW Data Acquisition VI Library, a series of VIs for using
LabVIEW with National Instruments DAQ hardware, is included with
LabVIEW. The LabVIEW Data Acquisition VI Library is functionally
equivalent to NI-DAQ software.
LabWindows/CVI features interactive graphics, state-of-the-art user
interface, and uses the ANSI standard C programming language. The
LabWindows/CVI Data Acquisition Library, a series of functions for
using LabWindows/CVI with National Instruments DAQ hardware, is
included with the NI-DAQ software kit. The LabWindows/CVI Data
Acquisition Library is functionally equivalent to the NI-DAQ softwar e.
VirtualBench features virtual instruments that combine DAQ pr oduct s,
software, and your computer to create a stand-alone instrument with the
added benefit of the processing, display, and storage cap abilities of
your computer. VirtualBench instruments load and save waveform data
to disk in the same forms that can be used in popular spreadsheet
programs and word processors.
Using ComponentWorks, LabVIEW, LabWindows/CVI, or
VirtualBench software will greatly reduce the development time
for your data acquisition and control application.
NI-DAQ Driver Software
The NI-DAQ driver software is included at no charge with all National
Instruments DAQ hardware. NI-DAQ is not packaged with SCXI or
accessory products, except for the SCXI-1200. NI-DAQ has an
extensive library of functions that you can call from your application
programming environment. These functions include routi nes for analog
input (A/D conversion), buffered data acquisition (high-speed A/D
conversion), analog output (D/A conversion), waveform generation
(timed D/A conversion), digital I/O, counter/timer operations, SCXI,
RTSI, self-calibration, messaging, and acquiring data to extended
memory.
NI-DAQ has both high-level DAQ I/O functions for maximum ease of
use and low-level DAQ I/O functions for maximum flexibility and
performance. Examples of high-level functions are streaming data to
disk or acquiring a certain number of data points. An example of a
low-level function is writing directly to registers on the DAQ device.
NI-DAQ does not sacrifice the performance of National Instruments
DAQ devices because it lets multiple devices operate at their peak.
National Instruments Corporation1-3PCI-6110E/6111E User Manual
Chapter 1Introduction
NI-DAQ also internally addresses many of the complex issues between
the computer and the DAQ hardware such as programming interrupts
and DMA controllers. NI-DAQ maintains a consistent software
interface among its different versions so that you can change platfor ms
with minimal modifications to your code. Whether you are using
conventional programming languages or National Instruments
application software, your application uses the NI-DAQ driver
software, as illustrated in Figure 1-1.
Figure 1-1. The Relationship between the Programming Environment,
Register-Level Programming
The final option for programming any National Instruments DAQ
hardware is to write register-level software. Writing register-level
programming software can be very time-consuming and inefficient,
and is not recommended for most users.
Conventional
Programming
Environment
DAQ or
SCXI Hardware
NI-DAQ, and Your Hardware
ComponentWorks,
LabVIEW,
LabWindows/CVI,
or VirtualBench
NI-DAQ
Driver Software
Personal Computer
or Workstation
Even if you are an experienced register-level programmer, using
NI-DAQ or application software to program your National Instruments
DAQ hardware is easier than, and as flexible as, register-level
programming, and can save weeks of development time.
National Instruments offers a variety of produ cts to use with the 611XE
board, including cables, connector blocks, and other accessories, as
follows:
•Cables and cable assemblies
•Connector blocks, shielded and unshielded 50- and 68-pin screw
terminals
•RTSI bus cables
•Low channel-count signal conditioning modules, boards, and
accessories, including conditioning for strain gauges, RTDs,
and relays
For more specific information about these products, refer to your
National Instruments catalogue or call the office nearest you.
Custom Cabling
National Instruments offers cables and accessories for you to prototype
your application or to use if you frequently change board
interconnections.
Chapter 1Introduction
If you want to develop your own cable, however, the following
guidelines may be useful:
•For the analog input signals, shielded twisted-pair wires for each
analog input pair yield the best results, assuming that you use
differential inputs. Tie the shield for each signal pair to the ground
reference at the source.
•Route the analog lines separately from the digital lines.
•When using a cable shield, use separate shields for the analog and
digital halves of the cable. Failure to do so results in noise coupling
into the analog signals from transient digital signals.
Mating connectors and a backshell kit for making custom 68-pin cables
are available from National Instruments.
National Instruments Corporation1-5PCI-6110E/6111E User Manual
Chapter 1Introduction
Unpacking
The following list gives recommended part numbers for connectors that
mate to the I/O connector on the 611X E board:
•Honda 68-position, solder cup, female connector
(part number PCS-E68FS)
•Honda backshell (part number PCS-E68LKPA)
The 611X E board is shipped in an antistatic package to prevent
electrostatic damage to the board. Electrostatic discharge can damage
several components on the board. To avoid such damage in handling
the board, take the following precautions:
•Ground yourself via a grounding strap or by holding a grounded
object.
•Touch the antistatic package to a metal part of your computer
chassis before removing the board from the package.
•Remove the board from the package and inspect the board for
loose components or any other sign of damage. Notify National
Instruments if the board appears damaged in any way. Do
install a damaged board into your computer.
This chapter explains how to install and configure your 611X E board.
Software Installation
Install your software before you install the 611X E board. Refer to the
appropriate release notes indicated below for specific instructions on
the software installation sequence.
If you are using LabVIEW, LabWindows/CVI, or other National
Instruments application software packages, refer to the appropriate
release notes. After you have installed your application software, refer
to your NI-DAQ release notes and follow the instructions given there
for your operating system and application software package.
If you are using NI-DAQ, refer to your NI-DAQ release notes. Find
theinstallation section for your operating system and follow the
instructions given there.
Hardware Installation
2
You can install the 611X E board in any available expansion slot in your
computer. However, to achieve best noise performance, leave as much
room as possible between the 611X E board and other boards and
hardware. The following are general installation instructions, but
consult your computer user manual or technical reference manual for
specific instructions and warnings.
1. Write down the 611X E board serial number in the
PCI-6110E/6111E Hardware and Software Configuration Form
AppendixD,
2. Turn off and unplug your computer.
3. Remove the top cover or access port to the I/O channel.
4. Remove the expansion slot cover on the back panel of the
computer.
National Instruments Corporation2-1PCI-6110E/6111E User Manual
Customer Communication
, of this manual.
in
Chapter 2Installation and Configuration
5.Insert the 611X E board into a 5 V PCI slot. Gently rock the board
to ease it into place. It may be a tight fit, but
into place.
6.If required, screw the mounting bracket of the 611X E board to the
back panel rail of the computer.
7.Replace the cover.
8.Plug in and turn on your computer.
The 611X E board is installed. You are now ready to configure your
software. Refer to your software documentation for configuration
instructions.
Board Configuration
Due to the National Instruments standard architecture for data
acquisition and the PCI bus specification, the 611X E board
is completely software configurable. You must perform two types
of configuration on the 611X E board—bus-related and data
acquisition-related configuration.
The 611X E board is fully compatible with the industry standard
PCI Local Bus Specification Revision 2.0
automatically perform all bus-related configurations and requires no
user interaction. Bus-related configuration includes setting the board
base memory address and interrupt channel.
do not force
. This allows the PCI system to
the board
Data acquisition-related configuration includes such settings as analog
input coupling and range, and others. You can modify these settings
using NI-DAQ or application level software, such as ComponentWorks,
LabVIEW, LabWindows/CVI, and VirtualBench.
National Instruments Corporation3-1PCI-6110E/6111E User Manual
Chapter 3Hardware Overview
Figure 3-2 shows a block diagram for the PCI-6111E board.
CH0+
AI CH0
Mux
CH0-
CH1+
AI CH1
Mux
CH1-
Calibration
Mux
Trigger Level
Trigger
I/O Connector
DACs
PFI / Trigger
Timing
Digital I/O (8)
DAC0
DAC1
Analog Input
+
CH0
Amplifier
–
+
CH1
Amplifier
–
2
4
Analog
Trigger
Circuitry
Calibration
DACs
CH0
12-Bit ADC
CH1
12-Bit ADC
DAC
FIFO
CH0
Trigger
Counter/
Timing I/O
Digital I/O
12
12
Data (16)
Latch
CH1
Data (16)
Latch
AI Control
Analog Input
Timing/Control
DAQ - STC
Analog Output
Timing/Control
AO Control
Data (32)
DMA/IRQ
Bus
Interface
RTSI Bus
Interface
ADC
FIFO
IRQ
DMA
RTSI Bus
Figure 3-2. PCI-6111E Block Diagram
Data (32)
Analog
Input
Control
DAQ-STC
Bus
Interface
Analog
Output
Control
Generic
Bus
Interface
EEPROM
EEPROM
Control
FPGA
Mini
MITE
Interface
DMA
Interface
I/O
Bus
Interface
PCI
Bus
Control
Address/Data
PCI Bus
The analog input section for the 611X E board is software configurable.
You can select different analog input configurations through
application software. The following sections describe in detail each of
the analog input categories.
Input Mode
The 611X E board supports only differential inputs (DIFF). The DIFF
input configuration provides up to four channels on the PCI-6110E
board and up to two channels on the PCI-6111E board.
A channel configured in DIFF mode uses two analog channel input lines.
One line connects to the positive input of the board programmable gain
instrumentation amplifier (PGIA), and the other connects to the negative
input of the PGIA. For more information about DIFF input
The 611X E board has bipolar inputs only. Bipolar input m eans that the
input voltage range is between –V
a bipolar input range of 20V (±10 V).
You can program range settings on a per channel basis so that you can
configure each input channel uniquely.
The software-programmable gain on these boards increases their
overall flexibility by matching the input signal ranges to those that the
ADC can accommodate. They have gains of 0.2, 0.5, 1, 2, 5, 10, 20, and
50, and are suited for a wide variety of signal levels. With the proper
gain setting, you can use the full resolution of the ADC to measure the
input signal. Table3-1 shows the overall input range and precision
according to the gain used.
Table 3-1.
Range
Configuration
Analog Input Signal Connections
, which contains diagrams showing the
and + V
ref
/2
Actual Range and Measurement Precision
GainActual Input Range
/2. These boards have
ref
1
section in
Precision
2
–10 to +10 V0.2
0.5
1.0
2.0
5.0
10.0
20.0
50.0
1
Warning:
user-installed voltage divider reduces the voltage to within the input range of the DAQ
device. Input voltages greater than 42 V can damage the 611X E, any device connected to
it, and the host computer. Overvoltage can also cause an electric shock hazard for the
operator. National Instruments is NOT liable for damage or injury resulting from such
misuse.
2
The value of 1 LSB of the 12-bit ADC; that is, the voltage increment corresponding to a
National Instruments Corporation3-3PCI-6110E/6111E User Manual
The 611X E is not designed for input voltages greater than 42 V, even if a
See Appendix A,
Specifications
–50 to +50 V
–20 to +20 V
–10 to +10 V
–5 to +5 V
–2 to +2 V
–1 to +1V
–500 to +500 mV
–200 to +200 mV
, for absolute maximum ratings.
24.41 mV
9.77 mV
4.88 mV
2.44 mV
976.56 µV
488.28 µV
244.14 µV
97.66 µV
Chapter 3Hardware Overview
Input Coupling
Dither
Considerations for Selecting Input Ranges
The range you select depends on the expected range of the incoming
signal. A large input range can accommodate a large signal variation
but reduces the voltage resolution. Choosing a smaller input range
improves the voltage resolution but may result in the input signal going
out of range. For best results, match the input range as closely as
possible to the expected range of the input signal.
You can configure the 611X E board for either AC or DC input coupling
on a per channel basis. Use AC coupling when your AC signal contains
a large DC component. If you enable AC coupling, you remove the
large DC offset for the input amplifier and amplify only the AC
component. This makes effective use of the ADC dynamic range.
Dither adds approximately 0.5 LSBrms of white Gaussian noise to
the signal to be converted by the ADC. This addition is useful for
applications involving averaging to increase the resolution of the
611XE board, as in calibration or spectral analysis. In such
applications, noise modulation is decreased and differential linearity is
improved by the addition of the dither. When taking DC measurements,
such as when checking the board calibration, you should average about
1,000 points to take a single reading. This process removes the effects
of quantization and reduces measurement noise, resulting in improved
resolution.
Figure 3-3 illustrates the effect of dither on signal acquisition.
Figure 3-3a shows a small (±4 LSB) sine wave acquired without dither.
The ADC quantization is clearly visible. Figure 3-3b shows what
happens when 50 such acquisitions are averaged together; quantization
is still plainly visible. In Figure 3-3c, the sine wave is acquired with
dither. There is a considerable amount of visible noise. But averaging
about 50 such acquisitions, as shown in Figure 3-3d, eliminates both the
added noise and the effects of quantization. Dither has the effect of
forcing quantization noise to become a zero-mean random variable
rather than a deterministic function of the input signal.
You cannot disable dither on the 611X E board. This is because the
ADC resolution is so fine that the ADC and the PGIA inherently
produce almost 0.5 LSBrms of noise. This is equivalent to having a
dither circuit that is always enabled.
LSBs
LSBs
6.0
6.0
4.0
4.0
2.0
2.0
0.0
0.0
-2.0
-2.0
-4.0
-4.0
-6.0
-6.0
1002003004000500
1002003004000500
a. Dither disabled; no averagingb. Dither disabled; average of 50 acquisitions
LSBs
LSBs
6.0
6.0
4.0
4.0
2.0
2.0
0.0
0.0
-2.0
-2.0
-4.0
-4.0
-6.0
-6.0
1002003004000500
1002003004000500
c. Dither enabled; no averagingd. Dither enabled; average of 50 acquisitions
LSBs
LSBs
6.0
6.0
4.0
4.0
2.0
2.0
0.0
0.0
-2.0
-2.0
-4.0
-4.0
-6.0
-6.0
LSBs
LSBs
6.0
6.0
4.0
4.0
2.0
2.0
0.0
0.0
-2.0
-2.0
-4.0
-4.0
-6.0
-6.0
1002003004000500
1002003004000500
1002003004000500
1002003004000500
Figure 3-3. Effects of Dither on Signal Acquisition
Analog Output
The 611X E boa r d supplies two channels of analog output voltage at the
I/O connector. The range is fixed at bipolar ±10 V.
National Instruments Corporation3-5PCI-6110E/6111E User Manual
Chapter 3Hardware Overview
Analog Trigger
Note:The PFI0/TRIG1 pin is an analog input when configured as an analog
trigger. Therefore, it is susceptible to crosstalk from adjacent pins, which
can result in false triggering when the pin is left unconnected. To avoid
false triggering, make sure this pin is connected to a low-impedance signal
source (less than 1 kΩ source impedance) if you plan to enable this input
via software.
In addition to supporting internal software triggering and external
digital triggering to initiate a data acquisition sequence, these boards
also support analog triggering. You can configure the analog trigger
circuitry to accept either a direct analog input from the PFI0/TRIG1 pin
on the I/O connector or a postgain signal from the output of the PGIA
on any of the channels, as shown in Figures 3-4 and 3-5. The
trigger-level range for the direct analog channel is ±10 V in 78 mV steps
for the 611X E board. The range for the post-PGIA trigger selection is
simply the full-scale range of the selected channel, and the resolution is
that range divided by 256.
Figure 3-5. Analog Trigger Block Diagram for the PCI-6111E
Five analog triggering modes are available, as shown in Figures 3-6
through 3-10. You can set lowValue and highValue independently in
software.
In below-low-level analog triggering mode, the trigger is generated
when the signal value is less than lowValue, as shown in Figure 3-6.
HighValue is unused.
lowValue
Trigger
Figure 3-6. Below-Low-Level Analog Triggering Mode
National Instruments Corporation3-7PCI-6110E/6111E User Manual
Chapter 3Hardware Overview
In above-high-level analog triggering mode, the trigger is generated
when the signal value is greater than highValue, as shown in Figure 3-7.
LowValue is unused.
highValue
Trigger
Figure 3-7. Above-High-Level Analog Triggering Mode
In inside-region analog triggering mode, the trigger is generated when
the signal value is between the lowValue and the highValue, as shown
in Figure 3-8.
In high-hysteresis analog triggering mode, the trigger is generated when
the signal value is greater than highValue, with the hysteresis specified
by lowValue, as shown in Figure 3-9.
highValue
lowValue
Trigger
Figure 3-9. High-Hysteresis Analog Triggering Mode
In low-hysteresis analog triggering mode, the trigger is generated when
the signal value is less than lowValue, with the hysteresis specified by
highValue, as shown in Figure 3-10.
highValue
lowValue
Trigger
Figure 3-10. Low-Hysteresis Analog Triggering Mode
The analog trigger circuit generates an internal digital trigger based on
the analog input signal and the user-defined trigger levels. This digital
trigger can be used by any of the timing sections of the DAQ-STC,
including the analog input, analog output, and general-purpose
counter/timer sections. For example, the analog input section can be
configured to acquire n scans after the analog input signal crosses a
specific threshold. As another example, the analog output section can
be configured to update its outputs whenever the analog input signal
crosses a specific threshold.
National Instruments Corporation3-9PCI-6110E/6111E User Manual
Chapter 3Hardware Overview
Digital I/O
The 611X E board contains eight lines of digital I/O for general-purpose
use. You can individually software-configure each line for either input
or output. At system startup and reset, the digital I/O ports are all high
impedance.
The hardware up/down control for general-purpose counters 0 and 1 are
connected onboard to DIO6 and DIO7, respectively. Thus, you can use
DIO6 and DIO7 to control the general-purpose counters. The up/down
control signals are input only and do not affect the operation of the DIO
lines.