Keithley KUSB-3100 User Manual
KUSB-3100
User’s Manual
KUSB3100-900-01 Rev. A / January 2005
www.keithley.com
A GR
EATER MEASURE OF CONFIDENCE
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 3 years from
date of shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries,
diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You
will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility.
Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance
of the original warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse
of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leak
age, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN
ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
-
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRU
MENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE
POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO:
COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR
DAMAGE TO PROPERTY.
A G R E A T E R M E A S U R E O F C O N F I D E N C E
-
Keithley Instruments, Inc.
Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139
440-248-0400 • Fax: 440-248-6168 • 1-888-KEITHLEY (534-8453) • www.keithley.com
12/04
KUSB-3100
User’s Manual
©2005, Keithley Instruments, Inc.
All rights reserved.
First Printing, January 2005
Cleveland, Ohio, U.S.A.
Document Number: KUSB3100-900-01 Rev. A
Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released
between Revisions, contain important change information that the user should incorporate immediately into the manual.
Addenda are numbered sequentially. When a new Revision is created, all Addenda associated with the previous Revision
of the manual are incorporated into the new Revision of the manual. Each new Revision includes a revised copy of this
print history page.
Revision A (Document Number KUSB3100-900-01A) ...................................................................... January 2005
All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders.
Safety Precautions
The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in
struments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury. Read and follow all installation,
operation, and maintenance information carefully before using the
product. Refer to the manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product may be impaired.
The types of product users are:
Responsible body is the individual or group responsible for the use
and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en
suring that operators are adequately trained.
Operators use the product for its intended function. They must be
trained in electrical safety procedures and proper use of the instru
ment. They must be protected from electric shock and contact with
hazardous live circuits.
Maintenance personnel perform routine procedures on the product
to keep it operating properly, for example, setting the line voltage
or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by
service personnel.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained ser
vice personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that
are rated Measurement Category I and Measurement Category II, as
described in the International Electrotechnical Commission (IEC)
Standard IEC 60664. Most measurement, control, and data I/O sig
nals are Measurement Category I and must not be directly connected to mains voltage or to voltage sources with high transient overvoltages. Measurement Category II connections require protection
for high transient over-voltages often associated with local AC
mains connections. Assume all measurement, control, and data I/O
connections are for connection to Category I sources unless other
wise marked or described in the Manual.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures.
The American National Standards Institute (ANSI) states that a
shock hazard exists when voltage levels greater than 30V RMS,
42.4V peak, or 60VDC are present. A good safety practice is to ex
pect that hazardous voltage is present in any unknown circuit
before measuring.
Operators of this product must be protected from electric shock at
-
all times. The responsible body must ensure that operators are pre
vented access and/or insulated from every connection point. In
some cases, connections must be exposed to potential human con
tact. Product operators in these circumstances must be trained to
protect themselves from the risk of electric shock. If the circuit is
capable of operating at or above 1000 volts, no conductive part of
the circuit may be exposed.
Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con
necting sources to switching cards, install protective devices to limit
fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connected to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.
When installing equipment where access to the main power cord is
restricted, such as rack mounting, a separate main input power dis
connect device must be provided, in close proximity to the equip-
ment and within easy reach of the operator.
For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jump
ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Always
make measurements with dry hands while standing on a dry, insulated
surface capable of withstanding the voltage being measured.
The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip
ment may be impaired.
Do not exceed the maximum signal levels of the instruments and ac-
cessories, as defined in the specifications and operating information, and as shown on the instrument or test fixture panels, or
switching card.
When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.
Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a
lid interlock.
-
-
-
-
-
-
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5/03
If a screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.
!
The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.
The symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.
The symbol indicates a connection terminal to the equipment
frame.
The WA RN ING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.
The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and
all test cables.
To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instruments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se
lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill on
the instrument. Products that consist of a circuit board with no case
or chassis (e.g., data acquisition board for installation into a com
puter) should never require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected,
the board should be returned to the factory for proper cleaning/ser
vicing.
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Table of Contents
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Intended Audience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
What You Should Learn from this Manual. . . . . . . . . . . . . . . . . . xi
Conventions Used in this Manual . . . . . . . . . . . . . . . . . . . . . . . . . xii
Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Where To Get Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Chapter 1: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2: Principles of Operation . . . . . . . . . . . . . . . . . . . . 5
Analog Input Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Specifying a Single Analog Input Channel . . . . . . . . . . . 7
Specifying One or More Analog Input Channels . . . . . . 8
Input Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Input Ranges and Gains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Specifying the Gain for a Single Channel . . . . . . . . . . . 10
Specifying the Gain for One or More Channels . . . . . . 10
Input Sample Clock Sources . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Analog Input Conversion Modes . . . . . . . . . . . . . . . . . . . . . . 11
Single-Value Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Continuous Scan Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Input Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Data Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
vii
Contents
Analog Output Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Analog Output Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Specifying a Single Analog Output Channel . . . . . . . . 16
Specifying Analog Output Channels . . . . . . . . . . . . . . . 17
Output Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Output Ranges and Gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Output Trigger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Output Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Output Conversion Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Single-Value Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Continuous Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 19
Data Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Digital I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Digital I/O Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Operation Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Counter/Timer Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
C/T Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
C/T Clock Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Gate Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Pulse Duty Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Counter/Timer Operation Modes . . . . . . . . . . . . . . . . . . . . . 28
Event Counting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Frequency Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 29
Edge-to-Edge Measurement . . . . . . . . . . . . . . . . . . . . . . 30
Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
viii
Chapter 3: Supported Device Driver Capabilities. . . . . . . . 33
Chapter 4: Programming Flowcharts. . . . . . . . . . . . . . . . . . 43
Single-Value Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Continuous A/D Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Continuous D/A Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Event Counting Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Frequency Measurement Operations . . . . . . . . . . . . . . . . . . . . . . 53
Edge-to-Edge Measurement Operations . . . . . . . . . . . . . . . . . . . 55
Pulse Output Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Simultaneous Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Chapter 5: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . 73
General Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Service and Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Chapter 6: Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Using the KUSB-3100 Calibration Utility . . . . . . . . . . . . . . . . . . . 81
Calibrating the Analog Input Subsystem . . . . . . . . . . . . . . . . . . . 82
Connecting a Precision Voltage Source . . . . . . . . . . . . . . . . . 82
Using the Auto-Calibration Procedure . . . . . . . . . . . . . . . . . 82
Using the Manual Calibration Procedure . . . . . . . . . . . . . . . 83
Calibrating the Analog Output Subsystem . . . . . . . . . . . . . . . . . 85
Contents
Appendix A: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 87
Appendix B: Connector Pin Assignments . . . . . . . . . . . . . 99
Appendix C: Reading from or Writing to the
Digital Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
ix
Contents
x
About this Manual
This manual describes the features of the KUSB-3100 module, the
capabilities of the device driver, and how to program this module
using DT-Open Layers™ software. Troubleshooting information is
also provided.
Intended Audience
This document is intended for engineers, scientists, technicians, or
others responsible for using and/or programming the KUSB-3100
module for data acquisition operations in Microsoft® Windows 2000
or Windows XP. It is assumed that you have some familiarity with
data acquisition principles and that you understand your application.
What You Should Learn from this Manual
This manual provides detailed information about the features of the
KUSB-3100 module and the capabilities of the device driver. The
manual is organized as follows:
• Chapter 1, “Overview,” describes the major features of the
KUSB-3100 module, as well as the supported software for the
module.
• Chapter 2, “Principles of Operation,” describes all of the features
of the module and how to use them in your application.
• Chapter 3, “Supported Device Driver Capabilities,” lists the data
acquisition subsystems and the associated features accessible
using the device driver.
xi
About this Manual
• Chapter 4, “Programming Flowcharts,” describes the processes
you must follow to program the subsystems on the KUSB-3100
module using DT-Open Layers-compliant software.
• Chapter 5, “Troubleshooting,” provides information that you can
use to resolve problems with the module and the device driver,
should they occur.
• Chapter 6, “Calibration,” describes how to calibrate the analog
I/O circuitry of the KUSB-3100 module.
• Appendix A, “Specifications,” lists the specifications of the
module.
• Appendix B, “Connector Pin Assignments,” shows the screw
terminal assignments for the module.
• Appendix C, “Reading from or Writing to the Digital Registers,”
describes register-level functions you can use to program the
digital I/O lines of the module.
• An index completes this manual.
xii
Conventions Used in this Manual
The following conventions are used in this manual:
• Notes provide useful information or information that requires
special emphasis, cautions provide information to help you avoid
losing data or damaging your equipment, and warnings provide
information to help you avoid catastrophic damage to yourself or
your equipment.
• Items that you select or type are shown in bold.
Related Information
Refer to the following documents for more information on using the
KUSB-3100 module:
• KUSB-3100 Getting Started Manual provided with the module.
This manual describes how to install and wire signals to the
KUSB-3100 module.
• DataAcq SDK User’s Manual. For programmers who are
developing their own application programs using the Microsoft
C compiler, this manual describes how to use the DT-Open
TM
Layers
access the capabilities of your module.
• DTx-EZ Getting Started Manual. This manual describes how to use
the ActiveX controls provided in DTx-EZ
capabilities of your module in Microsoft Visual Basic® or Visual
C++®.
• DT-LV Link Getting Started Manual. This manual describes how to
use DT-LV Link
language to access the capabilities of your module.
DataAcq SDKTM in Windows 2000 or Windows XP to
About this Manual
TM
to access the
TM
with the LabVIEW® graphical programming
• Microsoft Windows 2000 or Windows XP documentation.
• USB web site (http://www.usb.org).
• Omega Complete Temperature Measurement Handbook and
Encyclopedia®. This document, published by Omega Engineering,
provides information on how to linearize voltage values into
temperature readings for various thermocouple types.
Where To Get Help
Should you run into problems installing or using your KUSB-3100
module, please call the Keithley Technical Support Department.
xiii
About this Manual
xiv
1
Overview
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1
Chapter 1
Features
The KUSB-3100 module is an economy, multifunction
mini-instrument.
Table 1: Key Features of the KUSB-3100 Module
Analog
Inputs
Analog
Outputs
Table 1 lists the key features of the module.
Resolution
I/O
Range
Sample
Rate
Digital
I/O
Counter/
a
Timer
8 SE
a. This counter/timer channel allows you to perform event counting, frequency
measurement, edge-to-edge measurement, and continuous pulse output (rate generation)
operations.
2
12-bit ±10 V
50 kS/s 8 in,
8 out
In addition, the KUSB-3100 module provides these features:
• 16-location channel-gain list. You can cycle through the
channel-gain list using continuous scan mode or triggered scan
mode.
• 2-location output channel list. You can update both analog
output channels simultaneously at up to 50 kSamples/s.
• 8 fixed digital input lines and 8 fixed digital output lines.
• One 32-bit counter/timer (C/T) channel that performs event
counting, frequency measurement, edge-to-edge measurement,
and rate generation operations (the resolution of the C/T is
16-bits in this mode).
• Internal and external A/D clock sources.
• Internal and external A/D trigger sources.
1
• No external power supply required. These are low-power
required (less than 100 mA draw).
2
Supported Software
The following software is provided with the KUSB-3100 module:
• Device Driver – This software must be installed and loaded
before you can use a KUSB-3100 module with any of the
supported software packages or utilities.
• The Quick Data Acq application – This application provides a
quick way to get your module up and running. Using the Quick
Data Acq application, you can verify the features of the module,
display data on the screen, and save data to disk.
• DataAcq SDK – This DT-Open Layers Software Develop Kit
(SDK) allows programmers to develop application programs for
the KUSB-3100 using the Microsoft C compiler in Windows 2000
or Windows XP.
• DTx-EZ – This software package contains ActiveX controls that
allow Microsoft Visual Basic® or Visual C++® programmers to
access the capabilities of the KUSB-3100 module.
• DT-LV Link – This software package allows LabVIEW®
programmers to access the capabilities of the KUSB-3100 module.
Overview
1
1
1
1
1
1
1
1
1
3
Chapter 1
4
2
Principles of Operation
Analog Input Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Analog Output Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Digital I/O Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Counter/Timer Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5
Chapter 2
Figure 1 shows a block diagram of the KUSB-3100 module.
+2.5 V Reference
8-Channel Multiplexer
A/D Ch7
A/D Ch6
A/D Ch5
A/D Ch4
A/D Ch3
A/D Ch2
A/D Ch1
A/D Ch0
ESD Protected to 4000 V
DAC 1
DAC 0
From USB
Por t
A/D Clock
12-Bit A/D
Converter
12-Bit D/A
Converter
Power
Supply
32-Bit
Counter/Timer
+5 V
C/T Out 0
C/T Gate 0
C/T In 0
External Clock
External Trigger
Digital
I/O
ESD Protected to 4000 V
DOUT7
DOUT0
DIN7
DIN0
USB 2.0 or 1.1
Por t
Input FIFO
Figure 1: Block Diagram of the KUSB-3100 Module
6
Analog Input Features
This section describes the following features of analog input (A/D)
operations on the KUSB-3100 module:
• Analog input channels, described on this page;
• Input resolution, described on page 8;
• Input ranges and gains, described on page 9;
Principles of Operation
2
2
• Input sample clock sources, described on page 10;
• Analog input conversion modes, described on page 11;
• Input triggers, described on page 13;
• Data format and transfer, described on page 14; and
• Error conditions, described on page 15.
Analog Input Channels
The KUSB-3100 module provides eight single-ended analog input
channels. The module can acquire data from a single analog input
channel or from a group of analog input channels.
The following subsections describe how to specify the channels.
Specifying a Single Analog Input Channel
The simplest way to acquire data from a single analog input channel
is to specify the channel for a single-value analog input operation
using software; refer to
single-value operations.
page 11 for more information about
2
2
2
2
2
2
You can also specify a single channel using the analog input
channel-gain list, described in the next section.
2
7
Chapter 2
Specifying One or More Analog Input Channels
You can read data from one or more analog input channels using an
analog input channel-gain list. You can group the channels in the list
sequentially (starting either with 0 or with any other analog input
channel) or randomly. You can also specify a single channel or the
same channel more than once in the list.
Using software, specify the channels in the order you want to sample
them. You can enter up to 16 entries in the channel-gain list. The
channels are read in order from the first entry in the list to the last
entry in the list. Refer to
supported conversion modes.
The maximum rate at which the module can read the analog input
channels is 50
channels in the channel-gain list, the maximum sampling rate is
25
kSamples/s for each channel. Likewise, if you specify 16 analog
input channels in the channel-gain list, the maximum sampling rate is
3.125 kSamples/s for each channel.
kSamples/s. Therefore, if you specify two analog input
page 11 for more information about the
Input Resolution
The KUSB-3100 module provides a resolution of 12-bits. Note that the
resolution is fixed; it cannot be programmed in software.
8
Input Ranges and Gains
Principles of Operation
The KUSB-3100 module features an input range of ±10 V. Use
software to specify the input range. Note that this is the range for the
entire analog input subsystem, not the range per channel.
The KUSB-3100 module supports programmable gains to allow many
more effective input ranges.
effective input ranges for each module.
Table 2: Effective Input Range
Gain Bipolar Input Range
1 ±10 V
2 ±5 V
4 ±2.5 V
8 ±1.25 V
For each channel on the KUSB-3100 module, choose the gain that has
the smallest effective range that includes the signal you want to
measure. For example, if your analog input signal ranges between
–2.0 V and +2.0, specify a gain of 4 for the channel; the effective input
range for this channel is then –2.5 V to +2.5
best sampling accuracy for that channel.
Table 2 lists the supported gains and
V, which provides the
2
2
2
2
2
2
2
The way you specify gain depends on how you specified the
channels, as described in the following subsections.
2
2
9
Chapter 2
Specifying the Gain for a Single Channel
The simplest way to specify gain for a single channel is to specify the
gain for a single-value analog input operation using software; refer to
page 11 for more information about single-value operations.
You can also specify the gain for a single channel using an analog
input channel-gain list, described in the next section.
Specifying the Gain for One or More Channels
You can specify the gain for one or more analog input channels using
an analog input channel-gain list. Using software, set up the
channel-gain list by specifying the gain for each entry in the list.
For example, assume the analog input channel-gain list contains three
entries: channels 5, 6, and 7 and gains 2, 4, and 1. A gain of 2 is
applied to channel 5, a gain of 4 is applied to channel 6, and a gain of
1 is applied to channel 7.
10
Input Sample Clock Sources
You can use one of the following clock sources to pace an analog
input operation:
• Internal clock – Using software, specify the clock source as
internal and the clock frequency at which to pace the operation.
The minimum frequency of the internal clock is 30 Hz; the
maximum frequency of the internal clock is 50 kHz.
According to sampling theory (Nyquist Theorem), specify a
frequency that is at least twice as fast as the input’s highest
frequency component. For example, to accurately sample a 2 kHz
signal, specify a sampling frequency of at least 4 kHz. Doing so
avoids an error condition called aliasing, in which high frequency
input components erroneously appear as lower frequencies after
sampling.
Principles of Operation
• External clock – An external clock is useful when you want to
pace acquisitions at rates not available with the internal clock or
when you want to pace at uneven intervals. The minimum
frequency of the external clock can be less than 30 Hz; the
maximum frequency of the external clock is 50 kHz.
2
Connect an external clock to the Ext Clock In signal on the
KUSB-3100 module. Conversions start on the rising edge of the
external clock input signal.
Using software, specify the clock source as external. The clock
frequency is always equal to the frequency of the external sample
clock input signal that you connect to the module.
Analog Input Conversion Modes
The KUSB-3100 module supports the following conversion modes:
• Single-value operations, described on this page.
• Continuous scan operations, described on page 12.
Single-Value Operations
Single-value operations are the simplest to use. Using software, you
specify the range, gain, and analog input channel. The module
acquires the data from the specified channel and returns the data
immediately. For a single-value operation, you cannot specify a clock
source, trigger source, scan mode, or buffer.
2
2
2
2
2
2
Single-value operations stop automatically when finished; you
cannot stop a single-value operation.
2
2
11
Chapter 2
Continuous Scan Mode
Use continuous scan mode if you want to accurately control the
period between conversions of individual channels in a channel-gain
list.
When it receives a software trigger, the module cycles through the
channel-gain list, acquiring and converting the data for each entry in
the list (this process is defined as the scan). The module then wraps to
the start of the channel-gain list and repeats the process continuously
until either the allocated buffers are filled or until you stop the
operation. Refer to
The conversion rate is determined by the frequency of the internal
sample clock; refer to
sample clock. The sample rate, which is the rate at which a single
entry in the channel-gain list is sampled, is determined by the
frequency of the input sample clock divided by the number of entries
in the channel-gain list.
To select continuous scan mode, use software to specify the data flow
as continuous.
page 14 for more information about buffers.
page 10 for more information about the internal
12
Figure 2 illustrates continuous scan mode using a channel-gain list
with three entries: channel 0, channel 1, and channel 2. In this
example, analog input data is acquired on each clock pulse of the
input sample clock. When it reaches the end of the channel-gain list,
the module wraps to the beginning of the channel-gain list and
repeats this process. Data is acquired continuously.
Principles of Operation
Chan 0
Chan 1
Input
Sample
Clock
Initial trigger event occurs
Figure 2: Continuous Scan Mode
Input Triggers
A trigger is an event that occurs based on a specified set of
conditions. Acquisition starts when the module detects the initial
trigger event and stops when the specified number of samples has
been acquired (if the buffer wrap mode is none, described on
14), or when you stop the operation. Note that when you stop the
operation, the module completes the reading of the channel-gain list.
The KUSB-3100 module supports the following trigger sources:
• Software trigger – A software trigger event occurs when you
start the analog input operation (the computer issues a write to
the module to begin conversions). Using software, specify the
trigger source as a software trigger.
• External digital (TTL) trigger – An external digital (TTL) trigger
event occurs when the module detects a high-to-low transition on
the Ext Trig In signal connected to the module. Using software,
specify the trigger source as a falling-edge external digital trigger
(trigger source extra).
Chan 2
Chan 0
Chan 1
Chan 2
Data acquired continuously
Chan 0
Chan 2
Chan 1
Chan 0
Chan 1
Chan 2
page
2
2
2
2
2
2
2
2
2
13
Chapter 2
Data Transfer
Before you begin acquiring data, you must allocate buffers to hold
the data. During acquisition, a Buffer Done message is returned
whenever a buffer is filled. This allows you to move and/or process
the data as needed.
It is recommended that you allocate a minimum of three buffers for
analog input operations, specifying one of the following buffer wrap
modes in software:
• None – Data is written to multiple allocated input buffers
continuously; when no more empty buffers are available, the
operation stops. This wrap mode guarantees gap-free data.
• Multiple – Data is written to multiple allocated input buffers
continuously; if no more empty buffers are available, the module
overwrites the data in the current buffer, starting with the first
location in the buffer. This process continues indefinitely until
you stop it. This mode does not guarantee gap-free data.
14
Data Format
The KUSB-3100 module uses twos complement encoding to represent
bipolar input ranges. In software, the analog input value is returned
as a code.
To convert a twos complement code into a voltage, use the following
formulas:
LSB = FSR = 20 V = 0.0048828 V
2N 4096
Code
Offset Binary
= Code
Twos Complement
XOR 2
N-1
Principles of Operation
Vin = Code
where,
• FSR is the full-scale range (20 V).
• N is the input resolution (12 bits).
• LSB is the least significant bit (0.0048828 V).
• Vin is the analog voltage.
• Code
represent the voltage in twos complement notation.
• Offset is the actual minus full-scale value (–10 V).
• Code
the voltage in offset binary notation.
For example, assume that the software returns a code of 3072 for the
analog input value. Determine the analog input voltage as follows:
Code
Code
Vin = 1024 * 0.0048828 V + –10 V
Offset Binary
Twos Com p lem ent
OffsetBinary
Offset Binary
Offset Binary
* LSB + Offset
is the raw count used by the software to
is the raw count used by the software to represent
= Code
= 3072 XOR 2048 = 1024
Twos Complement
XOR 2
N-1
2
2
2
2
2
2
Vin = –5.00 V
Error Conditions
An overrun condition is reported if the A/D sample clock rate is too
fast. This error is reported if a new A/D sample clock pulse occurs
while the ADC is busy performing a conversion from the previous
A/D sample clock pulse. It is up to the host application to handle this
error either by ignoring the error or stopping acquisition. To avoid
this error, use a slower sampling rate.
2
2
2
15
Chapter 2
Analog Output Features
This section describes the following features of analog output
operations:
• Analog output channels, described on this page;
• Output resolution, described on page 17;
• Output ranges and gains, described on page 17;
• Output trigger, described on page 17,
• Output clock, described on page 18,
• Data format and transfer, described on page 21; and
• Error conditions, described on page 22.
Analog Output Channels
The KUSB-3100 module provides two analog output channels
(DACs). The module can output data from a single analog output
channel or from both analog output channels.
16
The following subsections describe how to specify the channels.
Specifying a Single Analog Output Channel
The simplest way to output data from a single analog output channel
is to use single-value analog output mode, specifying the analog
output channel that you want to update; refer to
information about single-value operations.
You can also specify a single analog output channel using the output
channel list, described in the next section.
page 18 for more
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