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DAS4800STIHR Series
User's Guide
frm Page 1 Monday, August 22, 1994 5:09 PM
DAS4800STIHR Series
User's Guide
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Revision B - August 1994
Part Number: 90490
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The information contained in this manual is believed to be accurate aad reliable. However, the
manufacturer assumes no responsibility for its use or for any infringements of patents or other rights of
third pwties that may result from its use. No license is granted by implication or otherwise under nny
patent rights of the manufacturer.
THE MANUFACTURER SHALL NOT BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES RELATED TO THE USE OF THIS PRODUCT. THIS PRODUCT
IS NOT DESIGNED WITH COMPONENTS OF A LEVEL OF RELIABILITY SUITABLE FOR USE
IN LIFE SUPPORT OR CRITICAL APPLICATIONS.
All brand and product names are trademarks or registered trademarks of their respective companies,
0 Copyrigbt Keithlcy Instruments, Inc., 1994.
All rights reserved. Reproduction or adaptation of any part of this documentation beyond that permitted
by Section 117 of the 1976 United States Copyright Act without permission of the Copyright owner is
unlawful.
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Table of Contents
Preface
1 Overview
SupportingSoftware . . ...... l-3
Accessories .. . ...... 1-5
2 Functional Description
Analog Input Features .......................... .2-3
Differential/Single-Ended Selection .2-3
Ground Selection for Single-Ended Inputs. ,2-3
Unipolar/BipolarSelection.................... . . . ...2-4
Channel-Gain Selection ...................... .2-5
Channel Expansion ....................... .2-5
Multiplexer Control Lines MUX 4 to MUX 7 .2-6
External Gain Control Line GEXT ......... . . . ...2-6
4 Gains and Ranges. ........................
Maximum Achievable Throughput Rates ......
. . . ...2-6
. . . ...2-7 4
Data Conversion Modes ...................... . .2-13
Clock Sources .............................. . . . ..2-I4
PacerClock. ............................ . . . ..2-I4
Burst Mode Conversion Clock. .............. . . . ..2-I5
Triggers ................................... . . . ..2-I6
Pre-Trigger Acquisition .................... . . ...2-IX
About-Trigger Acquisition .................. .2-19
Post-Trigger Acquisition ................... .2-19
Gates ..................................... . .2-l')
Data Transfer Modes. ........................ .2-20
Digital I/O Features ............................ .2-21
Using Digital Control Signal DOSTB . . . ...2-22
Using Digital Control Signal TGOUT ........... .2-22
Using Digital Control Signal SSHO ............. . . ...2-24
Power ....................................... .2-25
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3 Setup and Installation
Unwrapping and Inspecting a Board ....... .3-l
Installing the Software Package. ....... .3-2
Installing a DOS Software Package ....... .3-2
Installing the Windows Software Package ....... .3-3
Configuring the Board.. . ....... .3-4
Using the Configuration Utility ....... .3-5
Setting the Base Address. ....... .3-l
Installing the Board . ....... .3-a
4 Cabling and Wiring
Attaching an STA-18OOU.............................. .4-l
Attaching an STP-50 .................................. 4-4
Attaching SSH-8 Accessories .......................... .4-5
Attaching MB02 Backplanes. .......................... .4-6
Attaching EXP- 1800 Accessories ....................... .4-X
Connecting Signals .................................. .4-9
Precautions.. ................................... ..4- 9
Precautions for Using a DAS-1801ST Board at
High Gains. ................................ .4-9
Additional Precautions. ......................... .4-10
Connecting a Signal to a Single-Ended Analog Input .... .4-l I
Connecting a Signal to a Differential Analog Input ...... .4-l 1
Common Connection Schemesfor Differential Inputs .4-11
Avoiding Ground Loops with Differential Inputs ..... .4-13
Connecting Digital I/O Signals. ..................... .4-14
Connecting Digital Control Signals .................. .4-14
Connecting and Synchronizing Multiple Boards ........ .4- 15
5 The Control Panel
6 Calibration
Equipment Requirements. .............. ....... .,6-l
Potentiometers and Test Points .......... ....... ,.6-l
Calibration Utility .................... ....... .6-3
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7 Troubleshooting
Problem Isolation. .,.7-l
Identifying Symptoms and Possible Causes, .,.7-l
Testing the Board and Host Computer . ..7-4
Testing the Accessory Slot and I/O Connections . ..7-4
Technical Support .7-6
A Specifications
B Connector Pin Assignments
Main I/O Connector of DAS-IXOOSTiHR Series Boards .B-1
I/O Connectors J 1 and 52 of the STA- 1XOOUAccessory. .B-2
Connector 53 of the STA-18OOUAccessory .B-2
Connectors 54 to 57 and Jumper Pads 58 to J 11 of the
STA- 18OOU Accessory .B-3
c DAS-1800 Series External Driver
Running the DAS-1800 SeriesExternal Driver. .c-2
Accessing the DAS-1800 Series External Driver .c-2
Special Characteristics. .c-3
4 Pseudo-Digital Input/Output: Extended Functions.
Analog Triggering
.c-3
.C-6
4
Analog Trigger Parameters .c-9
Trigger Level Calculation .c-10
Trigger Hysteresis Calculation . .C-II
About Triggering . . . . .C-11
Software Interrupt Vectors .c-12
Driver Software Operating Specifications. .c-13
Error Messages. .C-16
D Kelthley Memory Manager
Installing and Setting Up the KMM. D-2
Using KMMSETUPEXE . . D-2
Using a Text Editor. D-3
Removing the KMM . . . D-4
Index
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List of Figures
Figure 2- 1. Block Diagram of DAS-lBOOST/HR Series
Boards .2-2
Figure 2-2. Timing of Conversion Modes for a Queue of
Channels4to7 .._ 2-13
Figure 2-3. Enabling Conversions with Software
Triggering/Gating and With Internal and
External Clock Sources .2-17
Figure 2-4. Enabling Conversions with a Hardware Trigger 2-18
Figure 2-5. Hardware Gate. . .2-20
Figure 2-6. Timing Relationship between Data from DO0
to DO3 and Latch Strobe DOSTB .2-22
Figure 2-7. Timing for the TGOUT Signal .2-23
Figure 2-8. Timing for SSHO Signal When Not Used
for SSH Hardware . .2-25
Figure 3-1. Location of Base Address Switch on
DAS-1800ST/HR Series Boards ,3-8
Figure 4-1. Connector Layout of an STA-1800U Accessory. .4-2
Figure 4-2. Cabling and Connections for Attaching an
STA-1800U Accessory to a DAS-lSOOST/HR
Series Board.. . . . . . . . . . . . . . . ...4-2
4 Figure 4-3. Pin Assignments for the Main I/O Connector of
a DAS-lXOOST/HR Series Board. ,4-3 4
Figure 4-4. Pin Assignments for Main I/O Connectors JI
and J2 of the STA-1800U Accessory ,4-4
Figure 4-5. Cabling and Connections for Attaching an
SSH-8 Accessory to a DAS-IXOOST/HR
Series Board. .4-5
Figure 4-6. Cabling and Connections for Attaching
MB02 Backplanes to an STA- 18OOU
Accessory. 4-6
Figure 4-7. Daisy-Chaining STA-I800U Accessories
with Attached MB02 Backplanes. .4-7
Figure 4-8. Daisy-Chaining EXP-1800 Accessories .4-X
Figure 4-9. Connections for Wiring a Signal Source to a
DAS-IXOOST/HR Series Board Configured
for Single-Ended Inputs ,4- I1
Figure 4-10. Three Types of Connections for Wiring a
Signal Source to a DAS- 1BOOST/HR
Series Board Configured for Differential
Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . ...4-12
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Figure 4-11. A Differential Input Configuration that Avoids a
Ground Loop .4-13
Figure 4-12. Differential Input Configuration with a
Ground Loop 4-14
Figure 4-13. Two Connection Schemesfor Synchronizing
Multiple Boards. .4-16
Figure 6-I. Potentiometers and Test Points on the
DAS-IXOOSTEIR Series Boards .6-2
Figure B-l. Phi Assignments for the Main I/O Connector
of a DAS-1800ST/HR Series Board.. .B-I
Figure B-2. Pin Assignments for Main I/O Connectors Jl
and J2 of the STA- 18OOU Accessory. .B-2
Figure B-3. Pin Assignments for STA-1800U Connector 53 .B-3
Figure B-4. Pin Layouts and Assignments for STA- 1XOOU
Connectors 54 to 37 and Jumper Pads 38 to
Jll . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..B-4
Figure C- 1. Analog Trigger Conditions .C-7
Figure C-2. Using a Hysteresis Value. .C-8
List of Tables
Table 2-1. DAS-180IST Gains and Ranges for Unipolar
4 and Bipolar Modes
Table 2-2. DAS- 1802ST and DAS-1802HR Gains and
.2-6 4
Ranges for Unipolar and Bipolar Modes .2-7
Table 2-3. DAS- 1800ST Series Board Throughput for
Channel-to-Channel Sampling in Bipolar
Mode with Fixed Gain .2-9
Table 2-4. DAS-1800ST Series Board Throughput for
Channel-to-Channel Sampling in Unipolar
Mode with Fixed Gain .2-9
Table 2-5. Maximum Throughput for DAS- 180I ST in
Bipolar Mode .2- 10
Table 2-6. Maximum Throughput for DAS-IXOIST in
Unipolar Mode. . . .2- 10
Table 2-7. Maximum Throughput for DAS- 1802ST in
BipolarMode . . . . . . . . . . . . . . . . . 2-11
Table 2-8. Maximum Throughput for DAS- 1802ST in
UnipolarMode . . . . . . . . .._...... 2-11
Table 2-9. Maximum Throughput for DAS-1802HR in
Bipolar Mode .2- 12
Table 2- 10. Maximum Throughput for DAS- 1802HR in
Unipolar Mode. .2- 12
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Table 7-1. Troubleshooting Information. .7-2
Table A- 1. Analog Input Specifications for DAS180OST
Series ,,.......,.,........,......, A-l
Table A-2. Analog Input Specifications for DAS1802HR A-4
Table A-3. Digital I/O Specifications A-6
Table A-4. Power Supply Requirements A-6
Table C-l. Pseudo-Digital Input Channel .c-3
Table C-2. Pseudo-Digital Output Channels, .c-4
Table C-3. Count Value Rangesfor DAS- I BOOST/HR
Series Boards .c-7
Table C-4. BitValue for Analog Trigger Level aud
Trigger Hysteresis .c-10
Table C-5. Interrupt Vectors .~ . . .c-12
Table C-6. Analog Input Support . .C-13
Table C-7. Digital Input Support. .c-14
Table C-8. Digital Output Support .c-15
Table C-9. Counter/Timer Function Support. .C-16
Table C- 10. Error/Status Codes. .C- 16
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reface.frm Page ix Monday, August 22, 1994 5: 10 PM
Preface
This guide is intended to help you understand the installation, interface
requirements, functions and operation of the DAS- 1801ST, DAS- 1802ST,
and DAS-1802HR boards. Unless this guide refers specifically to the
DAS-lXOlST, DAS-1802ST, or DAS-1802HR board, it refers to all
boards collectively as the DAS- ISOOSTjHRSeries boards. At the same
time, the term DA.51 800 Series refers to all members of the DAS- 1800
family of data acquisition boards.
This guide focuses primarily on describing the DAS-1800ST/HR Series
boards and their capabilities, setting up the boards and their associated
software, making typical hookups, and operating the Control Panel
+D software. There are also chapters on calibration and troubleshooting. To
follow the information and instructions contained in this manual, you
must be familiar with the operation of an IBMrM PC AT0 (or cquivaleut)
in the MS-DOS@ or Windows'rMenvironments. You must also be familiar
with data-acquisition principles and their application.
The DAS-IROOSTIHR Series User's Guide is organized as follows:
. Chapter I describes the boards' features, accessories,and soliwarc
options.
. Chapter 2 describes operating features of the boards in more detail.
This chapter contains a block diagram and brief descriptions of the
features as they relate to your options for setting up and using the
boards.
l Chapter 3 contains instructions for inspection, software installation,
configuration, and board installation.
. Chapter 4 shows the preferred methods of making I/O (Input/Output)
connections, using the available accessoriesand cables.
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. Chapter 5 briefly describes the Control Panel program and gives
instructions for starting up the program from both DOS and
Windows.
. Chapter 6 discussescalibration requirements and gives instructions
for starting the calibration program from DOS.
. Chapter 7 contains information on isolating and determining the
source operatiug
of problems.
. Appendix A contains specifications for the DAS-1800ST/HR Series
boards.
. Appendix B contains pin assignmentsfor the main I/O connector of
DAS- 1800ST/HR Series boards and for the I/O and accessory
connectors of STA-l8OOU Screw Terminal accessories.
. Appendix C discussesthe External Driver for the VIEWDAC' and
ASYST@programs.
. Appendix D discussesthe Keithley Memory Manager and its use.
4 . An index completes the manual, 4
4I hapOlL.frm Page 1 Monday, August 22, 1994 5:lO PM
Overview
The DAS- 1800ST/HR Series boards perform data acquisition in IBM PC
AT, or compatible, computers. The DAS180lST is a 12-bit, high-gain
board, while the DAS-1802ST is a 12.bit, low-gain board. The
DAS1802HR is a l6-bit, low-gain board. Major features of these boards
are as follows:
. The boards make 16-bit data transfers on the AT bus.
. The boards are software-configurable for 16 single-ended or 8
differential analog input, onboard channels or up to 256 single-ended
or 128 differential channels using expansion accessories.
4 . Channels are individually software-configurable for gain,
. DAS1800ST Series boards acquire data at up to 333 ksamples/s and
I'&bit resolution,
. DAS1802HR boards acquire data at up to 100 ksamples/s and lh-bit
resolution.
. A 1024~locationFIFO (First In First Out) data buffer ensuresdata
integrity at all sampling rates.
. A 256-location channel/gain queue supports high-speed sampling at
the same or different gains and in sequential or non-sequential
channel order.
. Burst-mode data acquisition emulates simultaneous-sample-and-hold
(SSH) capability.
. The boards support external SSH hardware and EXP-1800 expansion
accessories.
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. External expansion accessoriesallow a board to acquire data from up
to 256 channels at the board's maximum acquisition rate.
. Dual-channel DMA (Direct Memory Access) operation allows the
acquisition of more than 64 ksamples.
. Pulsed interrupts allow multiple DAS-1800 Series boards to share
interrupt levels.
. Hardware trigger and gate for A/D (analog-to-digital) conversions
have software-selectable polarity.
. Triggering capabilities support pre-, post-, and about-trigger
acquisitions.
. The boards have four digital inputs.
l The bodrds have four digital outputs with a latch strobe.
. All user connections are made through a 50.pin I/O comiector at the
rear panel of the computer.
4 . All features are software-programmable except for a board's base
address switch.
. The boards provide 3!15V power for external circuitry.
For more information on these features, refer to the functional description
in Chapter 2.
1-2 Overview
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Supporting Software
The following software for DAS-lBOOST/HR Series boards supports all
currently available DAS-1800 Series boards:
. DAS-1800 Series standard software -This software, which is
provided on 3.5inch and 5.25inch diskettes, includes function
libraries for writing application programs under DOS iu a high-level
language such as Microsoft@ QuickBasic. Microsoft Professional
`TTM,
BASIC, and Microsoft Visual BasicTMfor DOS, support files,
example programs, and the following utility programs:
- Conrrol Pa& - The Control Panel (CTL1800.EXE) is a
DOS-based program. This program provides accessto all
DAS-1800 Series board operations without programming.
Operations include acquiring analog inputs and controlling digital
I/O. The Control Panel is a means of testing the board and your
application; it is also a means of performing simple applications
and saving data to a disk file. Refer to Chapter 5 for more
information about the Control Panel.
Configuration Utility - The configuration utility (CFG 1XOO.EXE)
is a program for creating or modifying a DAS-1800 Series
configuration file. A configuration file contains the configuration
setthigs for use by the DAS-1800 Series Function Call Driver and
other software. For more information on the coniiguratiou utility,
refer to "Configuring the Board" on page 3-4.
Calihrurion Lltiliry - The calibration utility (CAL1800,EXE) is a
DOS-based program for calibrating the analog I/O circuitry of
DAS-1800 Series boards. Refer to Chapter 6 for more
information about this utility.
Refer to the DAS-1800 Series Function Call Driver User's Guide for
more information ou programming with the standard software.
. ASO- - Advanced Software Option. This option is provided in
Windows and DOS versions; both versions are supplied on 3.5~inch
and 5.25~inchdiskettes, The ASO- includes function libraries for
application programs you write for MS-DOS and Windows
environments in Microsoft C/C++, Borland@ C/C++, Borland Turbo
1-3
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Pascal@,Microsoft Visual Basic for Windows, Microsoft QuickCO,
and Microsoft Visual C++rM. The ASO- package also contains
miscellaneous support files, example programs, and the following
utilities:
- Control Panel - The Control Panel is a stand-alone program
supplied in a DOS version (CTL1800,EXE) and a Windows
version (CTLlSOOW.EXE). This program provides accessto all
DAS-1800 Series board operations without programming.
Control Panel operations include acquiring analog inputs,
controlling analog outputs, and controlling digital I/O. The
Control Panel is a means of testing the board and your
application; it is also a means of performing simple applications
and saving data to a disk file. The Windows version allows you to
transfer acquired data to other Windows applications through the
Windows DDE (Dynamic Data Exchange) feature and supports
the graphing of up to eight channels on the display. Refer to
Chapter 5 for more information about the Control Panel.
Configuration Utility The configuration utility (CFG 1XOO.EXE)
is a program for creating or modifying a DAS- 1X00Series
4 configuration file. A configuration file contains the configuration
settings for use by the DAS-1800 Series Function Call Driver and 4
other driver software. For more information on the configuration
utility, refer to "Configuring the Board" on page 3-4.
- Culibrarion Utility -The calibration utility (CALlXOO.EXE) is a
DOS-based program for calibrating the analog I/O circuitry of
DAS- 1800 Series boards. Refer to Chapter 6 for more
information about this utility.
Refer to the DAS-1800 Series Function Call Driver User's Guide for
more information on programming with the ASO-1800.
. VDAS-1800 - VisualDAS Custom Controls for Visual Basic for
Windows for DAS-1800 Series boards. VisualDAS virtually reduces
setting up data acquisition operations to tilling in a table. The package
includes a comprehensive user's guide, offers extensive on-line help,
and furnishes software on 3.5~inch and 5.25.inch diskettes.
l Data acquisition and analysis application software - VIEWDAC is
an integrated software package available for the DAS- 1800 Series
1-4 Overview
4 4 I@
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boards. Programming tools, such as ASYST scientific and
engineering programming language, are also available to help you in
writing your application programs.
Note: If you use VIEWDAC or ASYST to program your DAS- 1800
Series board, you must use the DAS-1800 SeriesExternal Driver. This
driver is included in the DAS-I800 Series standard software package.
Refer to Appendix C for information on the external driver.
Accessories
The following accessoriesare available for use with DAS-I XOOST/HR
Series boards.
STA-18OOU- screw terminal accessory.This accessoryconnects to
the main I/O connector of a DAS-1800ST/HR Series board through a
CDAS-2000 cable to make all l/O signals accessiblethrough labeled
screw terminals.
STP-50 screw terminal panel. This accessoryprovides
general-purpose screw-terminal connections in a compact form
factor.
RMT-02 - rack mount enclosure for the STA- 18OOUaccessory.
SSH-8 - An 8.channel simultaneous sample and hold accessoryfor
the DAS- 18OOST/HR Series hoards. Refer to the SSH-8 User's Guide
for more information.
MB Series modules and MB02 backplanes - Plug-in, isolated,
signal-conditioning modules and backplanes (Refer to the MR Series
User's Guide for more information.)
EXP-1800 - 16.channel expansion accessorythat connects directly to
DAS-1800ST/HR Series boards. Refer to the EXP-1800 User's Guide
for more information.
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. PC-408A - DC/DC converter. This accessorymust he installed on
EXP-1800 accessoriesthat use external power.
. C-2600 - A 24.inch cable for connecting an STA-18OOUaccessoryto
an MB02 signal-conditioning backplane.
. CDAS-2000 - A 24-inch ribbon cable for connecting a
DAS-IBOOST/HR Series board to an STA-l8OOU, an STP-50, or an
EXP-1800.
. CACC-2000 - A 24.inch ribbon cable for daisy chaining additional
STA-18OOUaccessoriesto the first STA- 16OOU additional
or
EXP- 1800 accessoriesto the first EXP- 1800.
. C-1800 -An 18-inch ribbon cable with two Wpin female type D
connectors for connecting an STA-18OOUaccessoryto an SSH-8
accessory.
4
l-6 Overview
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2
Functional Description
This chapter describes the features of the analog input and digital I/O
sections of the DAS-1800ST/HR Series boards. These descriptions are
provided to familiarize you with the operating options and to enable you
to make the best use of your hoard. The block diagram in Figure 2-l on
page 2-2 representsboth the DASl800ST Series and the DAS-1802HR
boards.
2-1
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2-2 Functional Description
@ hap02Lfrm Page3 Monday, August 22, 1994 5: 11 PM
Analog Input Features
The analog input section of aDAS-lEOOST/HR Series board multiplexes
all the active input channels (up to 16 single-ended or 8 differential) down
to a single, sampling ADC (analog-to-digital converter). Sampling
resolution of the ADC is 1%bit (one part in 4096) for DAS-1800ST
Series boards and 16-bit (one part in 65,536) for the DAS-1802HR board.
Other features of the analog input section include software-configurable
inputs, a channel-gain queue, data conversion modes, data transfer modes,
and trigger and gate control, and clock sources.These features are
described in the following subsections.
Differential/Single-Ended Selection
Using the configuration software, you can set DAS-IXOOST/HR Series
boards to operate with either differential or single-ended inputs (see
"Configuring the Board" on page 3-4). Differential inputs measure the
difference between two signals. Single-ended inputs are referred to a
common ground, also called common-mode ground reference.
+b When you connect single-ended inputs to an STA-18OOUaccessory,you
cau use the accessory'sLLGND or U-CM MD screw terminals for your
common-mode ground reference. You specify your choice using the
configuration utility (see Chapter 2).
Generally, you want to use differential inputs for low-level signals whose
noise component is a significant part of the signal or if the signal has a
non-ground common mode. You want to use single-ended inputs for
high-level signals whose noise component is not significant.
The specific level at which one of these input configurations becomes
more effective than the other depends on the application. However, you
should use differential inputs for voltage ranges of 100 mV and below.
Ground Selection for Single-Ended Inputs
When you use single-ended inputs, you have two ways of grounding input
signals: the analog ground (default) and the user-common ground. The
two schemesdiffer in how the low side of the instrumentation amplifier is
connected. In the default mode, the low side of the amplifier is connected
2-3
hap02_.frm Page 4 Monday, August 22, 1994 5: 11 PM
to analog ground (LL GND). In the user-common mode, the low side of
the amplifier is connected to a pin on the connecter for user-common
ground (U-CM MD).
The user-common mode provides a meansfor eliminating ground loops in
the system by connecting the reference ground for inputs to the U-CM
MD input pin. Since the U-CM MD connection comrectsto the high
input impedance of the instrumentation amplifier, the signal contains no
power-supply return current.
The user-common mode also provides a means for making single-ended
measurementsof signals referred to a voltage that is not ground or whose
output range does not include ground. For example, a common way to
perform 4 to 20 mA current monitoring is to connect a loop with a
250 ohm resistor to ground; the resistor yields a 1 to 5 V output in this
current range. This method works but uses only 80% of the input range
when connected to a 0 to 5 V range. A better way is to use a 3 12.5 ohm
resistor and refer all measurementsto 1.25 V. The actual output voltage
then ranges from 1.25 V to 6.25 V; however, since the amplifier low side
is connected to 1.25 V, the measurementrange is now a span of 5 V,
making the entire input range available and increasing resolution of the
measurementsby 20%.
If you use single-ended input configurations, the user-common mode is
the recommended alternative. Use the default mode only if you want the
convenience of not having to connect a separatewire for low input.
UnipolaVBipolar Selection
Using the configuration software, you can set the DAS-1800ST/HR
Series boards to operate in either the unipolar or bipolar input mode (see
"Configuring the Board" on page 3-4). A unipolar signal is always
positive (0 to 5 V, for example), while a bipolar signal can swing up and
down between positive and negative peak values (*5 V, for example).
The DAS-IXOOST/HR Series boards use positive magnitude to represent
unipolar signals and twos complement for bipolar signals, In a given input
range with the same peak-voltage capacity for both modes, the unipolar
mode doubles the converter's resolution,
2-4 Functional Description
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Channel-Gain Selection
The DAS-1800ST/HR Series boards offer up to 16 single-ended or 8
differential onboard analog input channels. Using expansion accessories,
you can increase the number of available channels to 256 differential. To
accommodatechannel and gain settings for up to 256 channels, the
DAS-lEOOST/HR Series hoards contain a RAM storage circuit for a
256-position channel-gain queue. Each of the 256 queue positions holds
your choice of a chamiel number and a corresponding gain. You can enter
multiple channels sequentially or non-sequentially and with the sameor
different gain codes. Channel expansion, channel sequencing control, and
available gains and input ranges for DAS-lXOOST/FIR Series boards are
discussed in the following subsections.
Channel Expansion
If you require additional analog input channels, you can configure your
DAS- I XOOST/HR Seriesboard Carsingle-ended inputs and attach up to 16
EXP-1800 expansion accessoriesor up to 16 MB02 backplanes. Either
option can increase your input capacity to 256 channels.
If you use EXP-1800 accessories,you daisy-chain them directly to the
DAS-1800ST/HR Seriesboard using CDAS-2000 cables (see Chapter 4).
Since a DAS-lEOOST/HR Series board can not power a full complement
of EXP-1800 accessories,each EXP-1800 contains screw terminals for
attaching external power, a receptacle for a DC/DC converter, and a
switch for changing between internal and external power.
If you use MB02 backplanes, use one STA-ISOOU for every four
backplanes. Connect each group of four backplanes to an STA- IXOOUas
shown in Chapter 4, and daisy-chain any additional STA-IXOOU
accessoriesto the first STA-18OOU.
Sampling sequencesand gain settings for all expansion-board channels
are communicated through the control lines described in the following
two subsections.
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Multiplexer Control Lines MUX 4 to MUX 7
Multplexer lines MUX 4 to MUX 7 control the channel sequencing of
EXP- 1800 and MB02 expansion accessories.These lines carry the
channel-sequencing information from the channel-gain QRAM through
the main I/O connector of DAS-lXOOST/HR Series boards.
External Gain Control Line GEXT
External gain line GEXT setschannel gains on EXP- 1800 accessoriesto I
or 50. This line carries the channel gain settings from the channel-gain
QRAM through the main I/O connector of the DAS-1800STIHR Series
boards.
Gains and Ranges
The available gains and their corresponding input ranges are listed in
Table 2-1 for the DAS-1801ST and Table 2-2 for the DAS-1802ST and
DAS-1802HR.
4 Table 2-1. DAS-1801ST Gains and Ranges for Unipoiar and 4
Bipolar Modes
2-6 Functional Description
4 4
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Table 2-2. DA.51802ST and DAS-1802HR Gains and Ranges
for Unipolar and Bipolar Modes
Gain Unipoiar Range BiDoiar Ranae
Maximum Achievable Throughput Rates
Because you can change input ranges on a per-channel basis, throughput
is likely to drop if you group channels with varying gains in sequence.
The drop occurs becausethe channels with low-level inputs (magnitude
of 100 mV or less) are slower than those with high-level inputs and
becausethe channels with low-level inputs must drive out ihe residual
signals left by the high-level inputs. The best way to maximize
throughput is to use a combination of sensible channel grouping and
external signal conditioning. When using the channel-gain queue,
consider the following suggestions:
. Keep ail channels configured for a particular range together, even if
you have to arrange the channels out of sequence.
. If your application requires high-speed scanning of low-level signals,
use external signal conditioning to amplify the signal to f5 V or 0 to
5 V! This method offers the advantagesof increasing total system
throughput and reducing noise.
l If you are not using all the channels, you can make a particular
channel-gain entry twice to allow for settling time. In this case, you
want to ignore the results of the first entry.
l If you are measuring steady-statesignals, do not use the channel-gain
queue. Instead, use software to step through the channels and perform
single-channel acquisitions. For example, using software-controlled
single-channel acquisitions to acquire 1000 sampleson channel 0 at a
gain of 1 and then 2000 sampleson channel 1 at a gain of 250
virtually eliminates interference. This method is the best for
2-7
4
.frm Page 8 Monday, August 22,1994 5:11 PM
measuring steady-statesignals even if all the channels are at the same
gain.
You must give special consideration to the direct measurementof
low-level signals with the DAS1801ST board. When using the f20 mV,
0 to 20 mV, flO0 mV, or 0 to 100 mV ranges, measurementthroughput
drops for two reasons:
l The amplifier cannot settle quickly enough (particularly the f20 mV
and 0 to 20 mV ranges).
. Noise in the measurementsis higher and thus can require
post-acquisition filtering (averaging) to achieve accurate results.
The DAS- 1801ST has best noise performance if presented with a perfect
signal in these ranges, but perfect signals are virtually non-existent in the
real world. Since the DAS-1801ST has very high bandwidth (bandwidth
for low-level signals is about 8 to 10 MHz) any noise is amplified and
digitized. As a result, you must carry out the measurementof low-level
signals carefully to minimize noise effects.
Low-level transducers are best used with signal conditioning. Use the
4 f20 mV, 0 to 20 mV, flO0 mV, and 0 to 100 mV ranges with the 4
differential input mode.
The tables below show throughput for various configurations. Note that
these throughputs are based on driving the input with an idea1voltage
source. The output impedance and drive of the soume are far more critical
when making large gain changes between two channels whose inputs are
at opposite extremes of their input ranges, as when a signal near -20 mV
is measuredafter a signal at near +5 V. You will get better performance
driving adjacent channels at the same gain. The source needs to be able to
drive both the capacitance of the cable and the RC (resistor-capacitor)
product of the multiplexer resistance and the output capacitance of the
multiplexer and board. The multiplexer is typically about 360 a (1 ka
maximum) in series with 90 pF output capacitance.
On DASl800ST Series boards, the maximum throughput for sampling
one channel at any gain is 333 ksamples/s.The throughput for
channel-to-channel sampling with fixed gain in bipolar mode (0.024%
maximum error) is shown in Table 2-3.
2-a Functional Description
hap02Lfrm Page9 Monday, August 22, 1994 5:ll PM
Table 2-3. DAS-IBOOST Series Board Throughput for Channel-to-Channel
Sampling in Bipolar Mode with Fixed Gain
1 DAS-WOlST Input Range 1 DAS-1802ST Input Range 1 Throughput I
f20 mv 7S ksampleds
The throughput channel-to-channel
for sampling with fixed gain in
unipolarmode(0.024%maximumerror) is shown in Table 2-4.
Table 2-4. DA.51800ST Series Board Throughput for Channel-to-Channel
Sampling in Unipolar Mode with Fixed Gain
1 DAS-1801ST input Range 1 DAS-1802ST Input Range I Throughput /
I 0 to 2.50v I 312.5 ksampleds
I 0 to 1.00 v I I 312.5 ksampleds
I Oto20mV I I 60 ksamnlesls
2-9
hap02Lfrm Page IO Monday, August 22,1994 5:ll PM
The maximum throughput for aDAS-1801ST board, operating in bipolar
mode and having less than 1 LSB of error when driven from an ideal
voltage source, is shown in Table 2-5.
Table 2-5. Maximum Throughput for DAS-1601ST in Bipolar Mode
Maximum Throughput
To +5 V To il.0 V To k100 mV To f20 mV
From f5.0 V 312.5ksamples/s250 ksamples/s 200 ksamples/s 70 ksampleds
From flO0 mV 200 ksamples/s 312.5ksamples/s312.5ksamples/s70 ksamples/s
The maximum throughput for a DAS- 1801ST board, operating in
unipolar mode and having less than 1 LSB of error when driven from an
ideal voltage source, is shown in Table 2-6.
Table 2-6. Maximum Throughput for DAS-1601ST in Unipolar Mode
Maximum Throughput
ToOto5V IToOtoi.OV ~ToOto100mV~ToOto20mV
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The maximum throughput for a DASI802ST board, operating in bipolar
mode and having less than 1 LSB of error when driven from an ideal
voltage source, is shown in Table 2-7.
Table 2-7. Maximum Throughput for DAS-1802ST in Bipolar Mode
Maximum Throughput
To HO.0 V ITo k5.0 V jTo f2.50 V 1To+1.25V
The maximum throughput for a DAS1802ST board, operating in
tmipolar mode and having less than 1 LSB of error when driven from an
ideal voltage source. is shown in Table 2-8.
Table 2-0. Maximum Throughput for DAS-1802ST in Unipolar Mode
Maximum Throughput
To 0 to 10.0 V To 0 to 5.0 V To 0 to 2.5 V To 0 to 1.25 V
From 0 to 10.0 V 312.5 ksamplesh 312.5 ksamples/s 250 ksamples/s 200 ksamples/s
On DAS-1802HR boards, the maximum throughput for single-channel
operation is 100 ksamples/s.The maximum throughput for a
DAS1802HR board, operating in bipolar mode and having less than 2
LSBs of error when driven from an ideal voltage sonrcc, is shown in
Table 2-Y.
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Table 2-9. Maximum Throughput for DAS-1802HR in Bipolar Mode
The maximumthroughput for a DAS-1802HR board, operating in
unipolar mode and having less than 2 LSBs of error when driven from an
ideal voltage source, is shown in Table 2-10.
Table 2-10. Maximum Throughput for DAS-1802HR in Unipolar Mode
The worst-case error limit is the sum of the front-end settling time and the
effect of converter non-linearity. In many measurementsituations, this
error is tolerable. Note, however, that driving the inputs of channels to a
reasonable level of accuracy is often impractical because of the effects of
transducer output impedance and cable and interconnect impedance. For
best results, particularly with 16-bit systems,you should acquire all data
without changing the channel.
2-12 Functional Description
4 hap02Lfrm Page 13 Monday, August 22, 1994 5:ll PM 4
Data Conversion Modes
DAS-1800ST/HR Series boards support two modes of data conversion:
paced and burst. The conversion rate for each of these two modes is
controlled by a different clock: the pacer clock for paced mode and the
burst mode conversion clock for burst mode. Other differences between
the two data conversion modes are as follows:
. Paced mode - Pacedmode is the default data conversion mode and is
the mode best-suited for continuous scanning of a queue of channels
at a constant rate. In the paced mode, the conversion rate equals the
pacer clock rate. The sample rate, which is the rate at which a single
channel is sampled, is the pacer clock rate divided by the number of
channels in the queue.
. Burst mode In the burst mode, each pulse from the pacer clock
starts a scan of an entire queue of channels. The conversion rate
during a burst mode scan is equal to the rate of the burst mode
conversion clock. The sample rate, which is the rate at which a single
channel is sampled, is equal to the pacer clock rate.
4 Burst mode can also be used for pseudo-simultaneous
sample-and-hold in conjunction with DMA or interrupt operations.
4
Figure 2-2 shows the timing relationships of the paced and burst modes
for a queue of channel 4 to channel 7.
Pacer Clock
I I
Paced Mode Conversions CL4 Ch
I I
Burst Mcde Conversions CA4 OH5 CH