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over.frm Page 1 Monday, May 2, 1994 12:OSPM
DAS4800HC Series User's Guide
frm Page 1 Monday, May 2, 1994 12:OS PM
DAS-1800HC Series User's Guide
Revision B May 1994
Part Number: 78930
4&otlcep frm Page 2
`I Monday, May 2, 1994 12:08 PM
The information contained in this mruwd is believed to be iiccuratc sod reliable. However, the
mzumfecturer nssumes 110responsibility for its use or for any infringements of patents or other rights of
third parties that may result from its use. No liceme is granted by implication or otherwise uder zmy
patcot rights of the mnnufxturer.
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 hrxld and product oames are trndemxrks or registered trademarks of their respective cornpanics
0 Copyright Keithley Instmmcnts, Inc., 1994.
All rights reserved. Reproduction or ndaptntion of a11y
part of this documentation hcyond that permitted
by Sectioll 117 of the 1976 United States Copyright Act without permission of the Copyright owner is
!21itlwful.
1800ug.toc Page iii Monday, May 2, 1994 12:09 PM 4
Table of Contents
Preface
1 Overview
Supporting Software 1-2
Accessories .I-5
2 Functional Description
Analog Input Features ...... .2-3
Differential/Single-Ended Selection. ...... .2-r?
UnipolatYBipolar Selection. ...... .2-3
Channel-Gain Selection ...... .2-4
Gains and Ranges. . ...... .2-4
Maximum Achievable Throughput Rates ...... .2-5
Data Conversion Modes ....... 2-9
Clock Sources. ...... 2-11
Triggers..............................
Pre-Trigger Acquisition
..... .2-12
.... .,2-I 4 4
About-Trigger Acquisition.. ..... .2-14
Post-Trigger Acquisition _, .2-14
Gates................................ ..... .2-14
Data Transfer Modes. ..... .2-15
Analog Output Features ..... .2-16
Digital I/O Features . ... .,.2-l 7
Using Digital Inputs and Outputs ... .,.2-I 7
Using Digital Control Signal DOSTB ..... .2-17
Using Digital Control Signal TGOUT ... .,.2-1x
Using Digital Control Signal SSHO ... .,.2-l')
Power ..__......,.,,.,,.,..,.,,.,,.,., ..... .2-21
3 Setup and installation
Inspecting Contents of a DAS-18OOHC Series Package ,3-l
Installing the Software Package. ,3-2
Installing DOS Software. ,3-2
Installing Windows Software ,3-3
Configuring the Board. ,3-4
Using the Configuration File.. .1-S
2 LXOOugtoc Page iv Monday, May 2, 1994 12:09 PM
Default Configuration File. ....................... .3-5
Configuration Utility ............................ .3-6
Setting the Base Address. ........................... .3-X
Installing the Board .................................. .3-o
4 Cabling and Wiring
Attaching an STA-IXOOHC ............................ .4-l
Connecting to the CJC Sensor of an STA-IXOOHC. ......... .4-4
Attaching SSH-8 Accessories .......................... .4-5
Attaching MB01 Backplanes. .......................... .4-6
Attaching an STP- 100 ................................ .4-7
Connecting Signals .................................. .4-X
Precautions.. ................................... ..4- 8
Precautions for Using DAS-IXOlHC Boards
at High Gain ............................... .4-X
Additional Precautions. .......................... .4-q
Connecthig a Signal to a Single-Ended Analog Input ..... .4-o
Connecting a Signal to a Difhxntial Analog Input ...... .4- 10
Common Connection Schemesfor Differential Inputs .4- 10
Avoiding Ground Loops with Differential hiputs ..... .4- I2
Connecting Analog Output Signals. .................. .4-13
4 Connecting Digital I/O Signals. .....................
Connecting Digital Control Signals ..................
.4-13
.4-13
4
Connecting and Synchronizing Multiple Boards ........ .4-I4
5 The Control Panel
6 Calibration
Equipment Requirements. ............................. .6-l
Potentiometers and Test Points .......................... 6-I
Calibration Utility ................................... .6-Z
7 Troubleshooting
Problem Isolation. .7-I
Identifying Symptoms and Possible Causes. .7-l
Testing the Board and Host Computer .7-X
Testing the Accessory Slot and I/O Connections ,7-4
Technical Support . .7-5
A Specifications
iv
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6 lXOOug.toc Page v Monday, May 2, 1994 12:09 PM
B Connector Pin Assignments
I/O Connector for the DAS-IXOOHC Series Boards
and the STA-1XOOHC .B-I
STA- I XOOHC 37.Pin D Connectors. .B-3
c DAS-1800 Series External Driver
Running the DAS-1800 Series External Driver. ..... ...... .c-2
Accessing the DAS- 1800 Series External Driver .... ...... .c-2
Special Characteristics. ........................ ...... .c-3
Pseudo-Digital Input/Output: Extended Functions. ....... C-3
Analog Triggering ....................... ...... .C-6
Analog Trigger Parameters ................ ...... .c-9
Trigger Level Calculation. .............. ..... .c-IO
Trigger Hysteresis Calculation ........... .c-I1
About Triggering ........................ ..... .c-12
Software Interrupt Vectors ................... .... ..c-12
Error Messages ............................... ..... .c-13
D Keithley Memory Manager
Installihg and Setting Up the KMM. D-2
Using KMMSETUP.EXE .. . . . D-2
4 Using a Text Editor, D-3 4
Removing the KMM . D-4
Index
List of Figures
Figure 2-1. Block Diagram of DAS-1XOOHCSeries Boards. .2-2
Figure 2-2. Timing Relationships of Conversion Modes
for a Queue of Channels 4 to Channel 7 .2- 10
Figure 2-3. Enabling Conversions with Software
Triggering/Gating and With Internal
and External Clock Sources .2- I3
Figure 2-4. Enabling Conversions with a Hardware Trigger. 2- 13
Figure 2-5. Hardware Gate. .2- 15
Figure 2-6. Timing Relationship between Data from DO0
to DO7 and Latch Strobe DOSTB. .2- 18
Figure 2-7. Timing for the Generation of TGOUT .2- 19
Figure 2-X. Timing for SSHO Generation when not used
for SSH Hardware .2-20
4
4 lXOOug.toc Page vi Monday, May 2, 1994 12:09 PM 4
Figure 3-l. Location of Base Address Switch .3-Y
Figure 4-l. Cabling and Connections for Attaching an
STA- 1XOOHCAccessory .4-2
Figure 4-2. Pin Layouts and Assignments for I/O
Connectors of the DAS- 1XOOHC Series
Boards and the STA-1XOOHCBoard 4-3
Figure 4-3. CJC Sensor Circuit Schematic. .4-4
Figure 4-4. Location of CJC Sensor Screw
Terminals (TBI 1). .4-4
Figure 4-5. Cabling and Connections for Attaching
SSH-8 Accessories to a DAS-1800HC
Series Board, .4-5
Figure 4-6. Cabling and Connections for Attaching MB01
Backplanes to an STA-IXOOHC .4-6
Figure 4-7. Allaching an STP- 100 .4-7
Figure 4-X. Connections for Wiring a Signal Source to a
DAS- I XOOHCSeries Board Configured
for Single-Ended Inputs .4-10
Figure 4-9. Three Types of Connections for Wiring a
Signal Source to a DAS-IXOOHC Series
Board Configured for Differential Inputs. .4-l 1
4 Figure 4-10. A Differential Input Configuration that
Avoids a Ground Loop. .4-12
4
Figure 4-l 1. Differential Input Configuration with a
Ground Loop .4- 12
Figure 4-12. Two Connection Schemesfor Synchronizing
Multiple Boards. .4-15
Figure 6-l. Potentiometers and Test Points on the
DAS- I XOOHC Series Boards .6-2
Figure B-1. Pin Layouts and Assigmnents of the I/O
Connectors of DASl800HC Series Boards
and the STA-IXOOHC.. .B-2
Figure B-2. STA- I800HC Connector J 1. .B-3
Figure B-3. STA-IXOOHC Accessory Connector 52. .B-3
Figure B-4. STA-1XOOHCAccessory Connector 53. .B-4
Figure B-5. STA-1XOOHCAccessory Comicctor 54. .B-4
Figure C- 1, Analog Trigger Conditions .C-7
Figure C-2. Using a Hysteresis Value. .C-X
vi
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& 1800ug.toc Page vii Monday, May 2, 1994 12:09 PM
List of Tables
Tahlc 2-1. DAS-1801HC Gains and Ranges for Uuipolar
and Bipolar Modes . 2-4
Table 2-2. DAS-1802HC Gains and Ranges for Unipolar
and Bipolar Modes .2-4
Table 2-3. Throughput for Channel-to-Channel Sampling
in Bipolar Mode with Fixed Gain. .2-6
Table 2-4. Throughput for Channel-to-Channel Sampling
in Unipolar Mode with Fixed Gain. .2-7
Table 2-5. Maximum Throughput for DAS-180lHC
in Bipolar Mode .2-7
Table 2-6. Maximum Throughput for DAS-1801HC
in Unipolar Mode .2-X
Table 2-7. Maximum Throughput for DAS-1802HC
in Bipolar Mode . ,2-8
Table 2-8. Maximum Throughput for DAS-1802HC
in Unipolar Mode. .2-Y
Table 3- 1. Default Configuration File Settings. .3-5
Tahlc 7- 1. Troubleshooting Information. ,7-I
Table A- I. Analog Input Specifications A-l
Table A-2. Analog Output Specifications A-4
Table A-3. Digital I/O Specifications A-4
Table A-4. Power Supply Requirements A-5
Table C-l. Pseudo-Digital Input Channel .C-3
Table C-2. Pseudo-Digital Output Channels .C-4
Table C-3. Decimal Range of Count. .C- 10
Table C-4. BitValue for Analog Trigger Level, .C- IO
Table C-5. BitValue for Trigger Hysteresis .C- I I
Table C-6. Interrupt Vectors .C- 13
Table C-7. Error/Status Codes. . .C- 14
vii
2~ 18OOugtot Page viii Monday, May 2, 1994 12:09 PM
4P reface.frm Page ix Monday, May 2, 1994 12:09 PM 4
Preface
This guide is for persons needing to understand the installation, iutcrfacc
requirements, functions and operation of the DAS- 1XOlHC and
DAS- IXO2HC hoards. The two hoard models differ only in gain. Unless
this manual rcfcrs specifically to the DAS-IXOIHC hoard or the
DAS1802HC hoard, it refers to the two models collectively as lhc
DAS-1800HC Series hoards.
This guide focuses primarily on describing the DAS-IXOOHC Series
boards and their capabilities, setting up the hoards and their associated
software, making typical hookups, and operating the control-panel
software. There are also chapters on calibration and troubleshooting. To
4 follow the information and instructions contained in this manual, you
musl he familiar with the operation of an IBMTM PC AT0 in the
4
MS-DOS@ or Windows'rM environments. You must also he familiar with
dam-acquisition principles and their applications.
The DAS-1800HC Series User'L-Guide is organized as follows:
Chapter I describes die board's features, its accessories,and its
software options.
Chapter 2 describes operating matures of the boards in more detail.
The chapter contains a block diagram and brief descriptions of the
features as they relate to your options for setting up and using tbc
board.
Chapter 3 contains instructions for inspection, softwarc installation,
configuration, and board installation
Chapter 4 shows tbe preferred methods of making I/O (Input/Output)
connections, using the available I/O accessoriesand cables.
ix
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4 reface.frm Page x Monday, May 2, 1994 12:09 PM
l Chapter 5 briefly describes tbc Control Panel program and gives
instructions for starting up the program,
. Chapter 6 discussescalibration requirements and gives instructions
for starting the calibration program.
. Chapter 7 contains information on isolating and determining the
source of operating problems. This chapter also contains instructions
for obtaining technical support.
. Appendix A contains specifications for the DAS-IXOOHC Series
boards.
. Appendix B contains pin assignmentsfor the DAS-18OOHCSeries
hoard main I/O connector and of the four 37.pin accessoryconnectors
of the STA-1XOOHCscrew terminal accessory.
. Appendix C discussesthe External Driver for the VEWDAC" and
ASYST@programs.
. Appendix D discussestbe Keithley Memory Manager and its use
4
.frtn Page 1 Monday, May 2, 1994 12:lO PM
Overview
The DAS-1801HC and DAS-1802HC are high-perfonnancc data
acquisition boards for IBM PC AT or compatible computers. The
DAS-1801HC is a high-gain board, while the DAS-1802HC is a 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 64 single-ended or 32
differential analog input channels.
. Channels are individually software-configurable for gain
. The boards measure inputs at up to 333 ksamples/swith 12.bit
resolution.
. A 1024location FIFO (First In First Out) data buffer ensures data
integrity at all sampling rates.
. A 64.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.
. Single- or dual-DMA (Direct Memory Access) operation is
software-configurable.
. Interrupt levels are software-configurable.
1-l
.frtn Page 2 Monday, May 2,1994 12: 10 PM
Pulsed interrupts allow multiple boards to share interrupt levels.
Hardware A/D (analog-to-digital) trigger and gate have
software-selectable polarity.
Triggering capabilities support pre-, post-, and about-trigger
acquisitions.
Dual 12-bit DAC (digital-to-analog converter) outputs have
simultaneous updates.
The boards have four digital inputs.
The boards have eight digital outputs with latch strobe.
A lOO-pin I/O connector reyuires only one slot on rear panel of the
PC AT
For more information on these features,refer to the functional description
in Chapter 2.
4 Supporting Software 4
The following software is available for operating DASI8OOHC Series
boards:
. DAS-IS00 Series standard software package -This package, which
is used for the entire DAS-1800 series of boards, is provided on
3.5.inch and 5.25~inch diskettes and includes function libraries for
writing application programs under DOS in high-level languagessuch
as Microsoft@ QuickBasicT", Microsoft Professional BASIC, and
Microsoft Visual BasicTMfor DOS. This package also contains
support files, example programs, and the following utility programs:
Control Panel - The Control Panel (CTLI800,EXE) is a
DOS-based stand-alone program. This program provides access
to all DAS-1800HC Series board operations without
programming. These 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
l-2 Overview
41 4 j$
4 hapOl_.frm Page 3 Monday, May 2, lYY4 12:lO PM
application; it is also a means of performing simple applications
and saving data to a file. Refer to Chapter 5 for more information
about the Control Panel.
- Configurntion Utility The conliguration ulility
(D lXOOCFG.EXE)is a DOS-based program for creating or
modifying a DAS-1800 Series configuration file. A configuration
bile contains the settings used by the DAS-1800 Series Function
Call Driver and other driver software for configuring a board. For
more information on the configuration utility, refer to
"Configuring the Board" on page 3-4.
Calibration Utility -The calibration utility (CAL1800.EXE) is a
DOS-based program for calibrating the analog I/O circuitry of
DASl800HC Series boards. Refer to Chapter 6 for more
information about this utility.
Refer to the DAS-1800 Series Function Cull Driver User's Guide for
more information on the DAS-1800 Series standard software package.
. ASO- - Advanced Software Option, This option is provided in
Windows and DOS versions; both versions are supplied on 3.5.inch
4 and 5.25-inch diskettes. Tbc ASO- includes function libraries for 4
application programs you write for MS-DOS and Windows
environments in Microsoft C/C++, Borland@ C/C++, Borland Turbo
Pascal@,Microsoft Visual Basic for Windows, Microsoft QuickCB,
and Microsoft Visual C++TM.The ASO- also contains
miscellaneous support tiles, example programs, and the following
utilities:
- Control Punel -The Control Panel is a stand-alone program
supplied in a DOS version (CTL1800.EXE) and a Windows
version (CTLl800W.EXE). This program provides accessto all
DASI800HC 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 file. The Windows version also allows you to
transfer acquired data to other Windows applications and to graph
eight channels tbrougb the Windows DDE (Dynamic Data
l-3
4 4 4
4 hapOl_.frm Page 4 Monday, May 2, 1994 12: 10 PM 4
Exchange) feature. Refer to Chapter 5 Carmore information about
the Control Panel.
Corrfijilcrcriion Utility -The configuration utility
(D 18OOCFG.EXE) a program Corcrcaling or modifying a
is
DAS-1800 Series configuration file. A configuration file contains
the settings used by the DAS-1800 Series Function Call Driver
and other driver software for configuring a board. For more
information on the conIiguration utility, refer to "Configuring the
Board" on page 3-4.
Calibrution Utility - The calibration utility (CALlXOO.EXE) is a
DOS-basedprogram for calibrating the analog I/O circuitry of the
DASl800HC 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 the ASO-1800.
. VDAS-1800 - VisualDASTM Custom Controls for Visual Basic for
Windows. Offered as an alternative to the Function Call Driver,
VisualDAS helps Visual Basic programmers to develop applications
4 easily. The package includes a comprehensive user's guide, offers 4
extensive online help, and furnishes software on 3.5-inch and
5.25-inch diskettes.
. Data acquisition and analysis application software VIEWDAC is
an integrated software packages available for the DASI800HC
Series 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- I XOOHC
Series hoard, you must use the DAS-1800 Series External Driver. This
driver is included in the DAS-1800 Series standard software package.
Refer to Appendix C for information on the external driver.
1-4 Overview
4 14
4 hapOt_.frm Page 5 Monday, May 2, 1994 12: 10 PM
Accessories
Tbc following accessoriesare available for use witb tbc DAS-1800HC
Scrics boards:
STA-1800HC - screw terminal accessory.This accessoryconnects to
the DAS18OOHC Series main I/O connector through a CAB-1800
cable to bring all the I/O signals out to labeled screw terminals for
easy access.Refer to Chapter 4 for connections.
STP-100 - screw terminal panel. This accessoryprovides
general-purpose screw-terminal connections in a compact form
factor.
RMT-04 - rack mount enclosure for the STA-1800HC accessory.
SSH-8 - An X-channel Simultaneous Sample and Hold accessory for
the DAS-IXOOHC Series boards.
MB Series modules and backplanes -plug-in, isolated,
4 signal-conditioning modules and the backplanes that hold them. 4
C-16MBl a cable for connecting an STA-IXOOHC accessoryto an
MB0 I signal-conditioning backplane.
CAB-1800 - an 18-inch ribbon cable for counecting a DAS-IXOOHC
Series board to an STA- 1800HC or STP-100 accessory.
CAR-1801 - a 36-inch ribbon cable for connecting a DAS-18OOHC
Series board to an STA- 1XOOHC STP-100 accessory.
or
CAB-1800/S an 1X-inch shielded, ribbon cable for connecting a
DAS-1XOOHCSeries board to an STA-1XOOHCor STP-100
accessory.
1-5
4 4
4I hap0 ILfrm Page 6 Monday, May 2, 1YY4 12: 10 PM
4
l CAB-1801/S - a 36-inch shielded, ribbon cable for connecting a
DAS-1800HC Series board to an STA-1800HC or STP-100
accessory.
. C-1800 - an 1%inch ribbon cable with two 37.pin female type D
connectors for connecting an STA-1800HC accessoryto an SSH-X
accessory.
4
1-6 Overview
4 4
@ hapOZ-.frm Page 1 Monday, May 2, 1994 12:lO PM lo
2
Functional Description
This chapter describes features of the following DAS-1800HC Series
board sections: the analog input, the analog output, and the digital I/O.
These descriptions are offered lo familiarize you with the operating
options and to enable you to make the best USC your board. The block
of
diagram in Figure 2-1 representsboth the DAS-1HOlHC and the
DAS- I802HC.
2-1
4
>
1o:Ll oa
ElSO(1
[o:sl la
G OHS&--`-'
2 I I
frm Page 3 Monday, May 2, 1994 12: 10 PM
Analog lnwt Features
The analog input section of aDAS-1XOOHC Series board multiplexes all
the active input channels (up to 64 single-ended or 32 differential) down
to a single, 12-bit sampling ADC (analog-to-digital converter). Other
features of this section include software-configurable input modes, a
channel-gain queue, data conversion modes, data transfer modes, and
trigger and gate control. These Featuresare described in the following
subsections.
Differential/Single-Ended Selection
Using the configuration software, you can set DAS-1 XOOHC 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. Generally, you want to use differential inputs for
low-level signals whose noise component is a signiC&ml part of the signal
or if the signal has a non-ground common mode. You want to USC
single-ended inputs for high-level signals whose noise component is not
significant.
4
There is no specific level at which one of these input configuratimls
becomes more effective than the other. However, you should generally
use differential inputs for voltage ranges of 100 mV and below.
UnipolarlBipolar Selection
Using the configuration software, you can set the DAS-180OHC 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-1800HC Series boards use positive magnitude to represent
unipolar signals and twos complement for bipolar signals. In a given input
range with the samepeak-voltage capacity for both modes, the unipolar
mode doubles the converter's resolution.
2-3
4 4
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Channel-Gain Selection
The channel-gain queue is a RAM storage circuit for a 64.position queue.
Each of the 64 queue positions holds your choice of a channel number and
a corresponding gain. You can enter multiple channels sequentially or
non-sequentially and with the same or different gain codes. Available
gains and input ranges for both DAS-IXOOHC Series boards are listed in
the following subsection.
Gains and Ranges
The available gains and their corresponding and input ranges arc listed in
Tahlc 2-I for the DAS-1XOIHC and Table 2-2 for the DASl802HC.
Table 2-1. DAS-1801HC Gains and Ranges for Unipolar and
Bipolar Modes
Gain Unipolar Range Bipolar Range
4
Table 2-2. DAS-1802HC Gains and Ranges for Unipolar and
Bipolar Modes
2-4 Functional Description
Page 5 Monday, May 2, lYY4 12: 10 PM
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 the residual
signals left by the high-level inputs. The best way to maximize
throughput is to use a combination of sensible channel grouping and to
use external signal conditioning. When using the channel-gain queue,
consider the following suggestions:
. Put all channels that use the same range in the same group, 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 315V or 0 to
5 V. This method offers the advantagesof increasing total system
throughput and reducing noise.
l In the common case where the low-level inputs arc relatively
slow-speed and the high-level inputs are high-speed, you should
4 maintain two channci lists: one for low-speed inputs, the other for 4
high-speed inputs.
. If you arc not ushlg 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.
You must give special consideration to the direct measurementof
low-level signals with the DAS-IXOIHC. When using the f20 mV, 0 to 20
mV, ii00 mV, or 0 to IO0 mV ranges, measurementthroughput drops for
two reasons:
. The amplifier cannot settle quickly enough (particularly the f20 mV
and 0 to 20 mV ranges).
. Noise in the measurementsis higher and thus requires
post-acquisition filtering (averaging) to achieve accurate results,
The DASl80iHC would have better noise performance if presentedwith
a perfect signal in these ranges, but perfect signals are virtually
non-existent in the real world. Since the DAS- IXOlHC has very high
z-5
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4 Page 6 Monday, May 2, 1994 12:lO PM 4
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. Always use
the f20 mV, 0 to 20 mV, flO0 mV, and 0 to 100 mV ranges witb the
differential input mode.
The tables below show throughput for various configurations. Note that
these throughputs are based on driving the input with an ideal voltage
source. The output impedance and drive of tbc source is 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 capacilance 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 R (I k0
maximum) in series with 90 pF output capacitance.
The maximum throughput for sampling one channel at one gain (any
gain) is 333 ksamples/s.Tbc tbrougbput for channel-to-channel sampling
4 with fixed gain in bipolar mode (0.024% maximum error) is as shown in 4
Table 2-3.
Table 2-3. Throughput for Channel-to-Channel Sampling in Bipolar Mode with
Fixed Gain
2-6 Functional Description
4 4
.frtn Page 7 Monday, May 2, 1994 12: 10 PM
The throughput for channel-to-channel sampling with fixed gain in
unipolar mode (0.024% maximum error) is as shown in Table 2-4.
Table 2-4. Throughput for Channel-to-Channel Sampling in Unipolar Mode with
Fixed Gain
DAS-1801 HC Range DAS-1802HC Range Throughput
oto lO.OV 312.5ksamplrs/s
312.5ksamples/s
I 0 to 20 mv I I 60 ksamnlcs/s I
The maximum throughput for a DAS-lROIHC, operating in bipolar mode
and having less than 1 LSB of error when driven from an ideal voltage
source, is as shown in Table 2-5.
4
Table 2-5. Maximum Throughput for DAS-1801HC in Bipolar Mode
Maximum Throughput
To +5 V To t1.0 V To flO0 mV To 220 mV
Range
From 25.0 V 312.5ksamples/s 250 ksamples/s 200 ksamples/s 70 ks:unples/s
2-7
Page 8 Monday, May 2, 1994 12:lO PM
The maximum throughput for a DAS-lROlHC, operating in unipolar
mode and having less than 1 LSB of error when driven from an ideal
voltage source, is as shown in Table 2-6.
Table 2-6. Maximum Throughput for DAS-1601HC in Unipolar Mode
Maximum Throughput
Range ToOto5V To 0 to 1.0 V ToOtolOOmV ToOtoZOmV
From 0 to 5.0 V 312.5ksamplesls 200 ksamplcs/s 200 ksampleds 50 ksamplesls
~~~~~~~~~.:`"' ~~~~~~~~~~~ .~~~~~~~~~~~,.`:::::::: :::::::
:-::`:`:"::::`::::`:::::~~~~~~~~~~~ .:.:. .:.: ,:.;:,:.:.:,:.:,:^:~:,:~:.:,:.:.:,:.:::,~::;~~:::~~~:::~~~::::::i:::~~~:
:,:.:,:.:.:,:.:.:,:
,:.:.:, :,:.:.:,:.:,:;~:,:
::::::~::,:,:::,:.:.:,:.~.:
~~~~~ii:::::-i:i::::~::::i:::~:~:~::::~~:~~::::::::~~~:: :::::::
:::/:::::: ~~~~~~~~~~~~~~~~
::::::: :,:::
:::,::
::::::::::::::::::::,::~:::_:__::::::):~::::::;::::::::
::::::::::,::::::
From 0 to 100 mV 200 ksamW/s 250 ksamples/s 250 ksamples/s 60 ksamples/s
The maximum throughput for a DAS-1802HC, operating in bipolar mode
and having less than I LSB of error when driven from an ideal voltage
4 source, is as shown in Table 2-7.
Table 2-7. Maximum Throughput for DAS-1802HC in Bipolar Mode
Maximum Throughput
To f10.0 V To f5.0 V To +2.50 V To fl.25 V
Range
Z-8 Functional Description
4
Page 9 Monday, May 2, 1994 12: IO PM
The maximum throughput for a DAS- 1802HC, operating in unipolar
mode and having less than 1 LSB of error when driven from an ideal
voltage source, is as shown in Table 2-8.
Table 2-8. Maximum Throughput for DAS-1802HC in Unipolar Mode
Data Conversion Modes
DAS- I800HC Series boards support two modes ofdata conversion: paced
and burst. The conversion rate for each of these two modes is controlled
by its own 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- Paced mode is the default data conversion mode and is
the mode best-suited for continuous scanning of a qucuc 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.The internal pacer clock is programmable from
0.0012 Hz to 333 kHz.
. 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.
2-9
4
frm Page 10 Monday, May 2, lYY4 I2:lO PM I4
DAS-1800 Series software utilities allow you to program the pacer
clock to adjust the interval between burst mode scans.This software
also allows you to adjust the burst mode conversion rate. The burst
mode conversion clock frequency is programmable for a range of
15.625 Hz to 333 kHz.
Burst mode can also be used for pseudo-simultaneous
sample-and-hold in conjunction with DMA or interrupt operations.
Without SSH hardware attached to the DAS-1XOOHCSeries hoard,
the sample rate (pacer clock rate) should be set for no more than the
burst mode conversion clock rate divided by the number of channels
in the burst. The maximum burst mode conversion clock rate is
gain-sensitive. as explained in "Maximum Achicvablc Throughput
Rates" on page 2-5.
With SSH hardware attached to the DAS-ISOOHC Series board, the
sample rate (pacer clock ram) can he no more than the burst mode
conversion rate divided by the sum of one plus the number of
channels in the burst. For information on the signal interface between
a DAS-IXOOHC Series board and SSH hardware, refer to "Using
Digital Control Signal SSHO" on page 2- 19.
4 4
Figure 2-2 shows the timing relationships of the paced and burst modes
for a queue of channel 4 to channel 7.
Pacer Crook -j
I I
Paced Mode Conversion.3 CH4 ck
I I
CH4 Cy6 CH6 Cv7 Clj4 c+i Crp c/i7
I I I I I I I I
Burst Mode Convenions H{ld Ci,4 Ci,S Ck6 CH7 Hdld Cl!,4 C$5 $I6 CH7
I I I
(with SSH) I I I I I I I I I I
Burst Clock rlnnn nnnnn
Figure 2-2. Timing Relationships of Conversion Modes for a Queue of Channels 4 to
Channel 7
2-10 Functional Description
4 hapOl.frm Page 11 Monday, May 2, 1994 12: 10 PM 4+
Clock Sources
In paced mode, the pacer clock determines the A/D conversion rate. The
following clock sources are available for paced mode conversions on
DAS-1800HC Series boards:
. Software - DAS-ISOOHC Series boards allow you to acquire single
samples under program control.
. Hardware (internal clock source) - The internal pacer clock source
usesthe onboard 82C54 counter/timer and a crystal-controlled 5 MHz
time base.The internal pacer clock usestwo cascadedcounters of the
82C54 and is programmable between a maximum allowable rate of
333 kHz and a minimum available rate of 0.0012 Hz. When not used
to pace the analog input, the internal clock source can serve to pace
other events such as the digital I/O and analog outputs through the use
of interrupts.
. Hardware (external clock source) The external pacer clock source
must be an externally applied TTL-compatible signal attached lo the
DIO/XPCLK pin (839) of the main,I/O connector, Jl. The active edge
4 for this clock is programmable.
4
An external clock source is useful if you want to pace at rates not
available with the 82C54 counterhimer, if you wan1lo pace at uneven
intervals, or if you want to pace on the basis of an external event. An
external clock also allows you to synchronize multiple boards wilh a
common timing source.
Note: The ADC acquires samples at a maximum of 333 ksamples/s (one
sample every 3.0 us). If you are using an external clock, make sure that it
does not initiate conversions at a faster rate than the ADC can handle.
If you are acquiring samples from multiple channels, the maximum
sampling rate for each channel is equal to 333 ksamples/s divided by the
number of channels.
2-11
4 hap02Lfrm Page 12 Monday, May 2,1994 12: 10 PM
Triggers
A trigger starts an analog input operation. The polarity ofcxtemal triggers
in the DAS-IXOOHC Series boards is software-selectable. You can use
one of the following trigger snurces to start an analog input operation:
Internal - When you enable the analog input operation, conversions
begin immediately.
External Analog While an analog trigger is not a function of the
DAS-1800HC Seriesboards, you can program an analog trigger using
one of the analog input channels as the trigger channel. The
DAS-1800 Series Function Call Driver provides functions for an
analog trigger; refer to the DAS-1800 Series Function Call Driver
User's Guide for more information.
External Digital - Connect the digital trigger to the digital input DII
pin (B40) of the loo-pin connector, Jl. Trigger types arc as follows:
- Positive-edge trigger Triggering occurs on the rising edge of the
trigger signal.
4 Neguivc-edge trigger - Triggering occurs on the falling edge of 4
the trigger signal.
The actual points at which conversions begin depend on whether the
clock source is internal or external, as follows:
. Internal clock source The 82C54 counter/timer is idle until the
trigger occurs. Within 400 ns, the first conversion begins. Subsequent
conversions are synchronized to the internal clock.
. External clock source - Conversions arc armed when the trigger
occurs; they begin with the next active edge of the external clock
source and continue with subsequentactive edges.
Figure 2-3 illustrates conversions enabled with software triggering/gating
and with internal and external clock sources. In the diagram, the delay
between the start of the conversion process by software and the start of
the onboard clock is less than 1 ps, Figure 2-4 illustrates the enabling of
conversions with a hardware trigger.
2-12 Functional Description
4 4
4L hap02 -' frm Page 13 Monday, May 2, 1994 12: 10 PM 4
Conversions begin with
Software enables external 8O"ICB
COnYerSlo" proatss -1 (programmed for negative
I
I edge)
Conversions begl" with
internal clock SO"PX L:
Figure 2-3. Enabling Conversions with Software TriggeringlGating
and With Internal and External Clock Sources
*Trigger ocwrs (on positive edge)
4 4
TGIN input 7
TOOUT output
Figure 2-4. Enabling Conversions with a Hardware Trigger
2-13
4 4
Page 14 Monday, May 2, 1994 12:lO PM
Pre-Trigger Acquisition
In pre-trigger acquisition, the data of interest appearsbefore a specific
digital trigger. Acquisition starts on an internal, analog, or digital trigger
event and continues until the digital trigger. Pm-trigger acquisition is
avaliablc with DMA-mode operations only.
About-Trigger Acquisition
In about-trigger acquisition, the data of interest appears both before and
after a specific digital trigger. Acquisition starts on an internal, analog, or
digital trigger and continues until a specified number of sampleshas been
acquired after the digital trigger. About-trigger acquisition is avaliable
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