Tektronix DAS-1800AO Series Users Guide

DAS-1800AO Series

User’s Guide

A GREATER MEASURE OF CONFIDENCE

WARRANTY

Hardware

Keithley Instruments, Inc. warrants that, for a period of one (1) year from the date of shipment (3 years for Models 2000,
2001, 2002, 2010 and 2700), the Keithley Hardware product will be free from defects in materials or workmanship. This
warranty will be honored provided the defect has not been caused by use of the Keithley Hardware not in accordance with
the instructions for the product. This warranty shall be null and void upon: (1) any modification of Keithley Hardware that
is made by other than Keithley and not approved in writing by Keithley or (2) operation of the Keithley Hardware outside
of the environmental specifications therefore.

Upon receiving notification of a defect in the Keithley Hardware during the warranty period, Keithley will, at its option,
either repair or replace such Keithley Hardware. During the first ninety days of the warranty period, Keithley will, at its
option, supply the necessary on site labor to return the product to the condition prior to the notification of a defect. Failure
to notify Keithley of a defect during the warranty shall relieve Keithley of its obligations and liabilities under this
warranty.

Other Hardware

The portion of the product that is not manufactured by Keithley (Other Hardware) shall not be covered by this warranty,
and Keithley shall have no duty of obligation to enforce any manufacturers' warranties on behalf of the customer. On those
other manufacturers’ products that Keithley purchases for resale, Keithley shall have no duty of obligation to enforce any
manufacturers’ warranties on behalf of the customer.

Software

Keithley warrants that for a period of one (1) year from date of shipment, the Keithley produced portion of the software or
firmware (Keithley Software) will conform in all material respects with the published specifications provided such Keithley
Software is used on the product for which it is intended and otherwise in accordance with the instructions therefore.
Keithley does not warrant that operation of the Keithley Software will be uninterrupted or error-free and/or that the Keithley
Software will be adequate for the customer's intended application and/or use. This warranty shall be null and void upon any
modification of the Keithley Software that is made by other than Keithley and not approved in writing by Keithley.

If Keithley receives notification of a Keithley Software nonconformity that is covered by this warranty during the warranty
period, Keithley will review the conditions described in such notice. Such notice must state the published specification(s)
to which the Keithley Software fails to conform and the manner in which the Keithley Software fails to conform to such
published specification(s) with sufficient specificity to permit Keithley to correct such nonconformity. If Keithley deter­mines that the Keithley Software does not conform with the published specifications, Keithley will, at its option, provide
either the programming services necessary to correct such nonconformity or develop a program change to bypass such
nonconformity in the Keithley Software. Failure to notify Keithley of a nonconformity during the warranty shall relieve
Keithley of its obligations and liabilities under this warranty.

Other Software

OEM software that is not produced by Keithley (Other Software) shall not be covered by this warranty, and Keithley shall
have no duty or obligation to enforce any OEM's warranties on behalf of the customer.

Other Items

Keithley warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes,
and documentation.

Items not Covered under Warranty

This warranty does not apply to fuses, non-rechargeable batteries, damage from battery leakage, or problems arising from
normal wear or failure to follow instructions.

Limitation of Warranty

This warranty does not apply to defects resulting from product modification made by Purchaser without Keithley's express
written consent, or by misuse of any product or part.

Disclaimer of Warranties

EXCEPT FOR THE EXPRESS WARRANTIES ABOVE KEITHLEY DISCLAIMS ALL OTHER WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION, ALL IMPLIED WARRANTIES OF MERCHANT­ABILITY AND FITNESS FOR A PARTICULAR PURPOSE. KEITHLEY DISCLAIMS ALL WARRANTIES WITH
RESPECT TO THE OTHER HARDWARE AND OTHER SOFTWARE.

Limitation of Liability

KEITHLEY INSTRUMENTS SHALL IN NO EVENT, REGARDLESS OF CAUSE, ASSUME RESPONSIBILITY FOR
OR BE LIABLE FOR: (1) ECONOMICAL, INCIDENTAL, CONSEQUENTIAL, INDIRECT, SPECIAL, PUNITIVE OR
EXEMPLARY DAMAGES, WHETHER CLAIMED UNDER CONTRACT, TORT OR ANY OTHER LEGAL THEORY,
(2) LOSS OF OR DAMAGE TO THE CUSTOMER'S DATA OR PROGRAMMING, OR (3) PENALTIES OR PENALTY
CLAUSES OF ANY DESCRIPTION OR INDEMNIFICATION OF THE CUSTOMER OR OTHERS FOR COSTS, DAM­AGES, OR EXPENSES RELATED TO THE GOODS OR SERVICES PROVIDED UNDER THIS WARRANTY.

Keithley Instruments, Inc.

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-6202-2886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: Flat 2B, Willocrissa • 14, Rest House Crescent • Bangalore 560 001 • 91-80-509-1320/21 • Fax: [phone]
ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]
JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: [phone]
KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 679 • Fax: [phone]
SWITZERLAND: Kriesbachstrasse 4 • 8600 Dübendorf • 01-821 94 44 • Fax: [phone]
TAIWAN: 1FL., 85 Po Ai Street • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077• Fax: [phone]

28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

4/02

DAS-1800AO Series

User’s Guide

Revision D - August 2000

Part Number: 91280

The information contained in this manual is believed to be accurate and reliable. However, the
manufacturer assumes no responsibility for its use; nor for any infringements of patents or other rights
of third parties that may result from its use. No license is granted by implication or otherwise under any
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 THAT IS SUITED FOR
USE IN LIFE SUPPORT OR CRITICAL APPLICATIONS.

DriverLINX, SSTNET, and LabOBJX are registered trademarks and DriverLINX/VB is a trademark of
Scientific Software Tools, Inc.

Microsoft and Windows are registered trademarks and Visual C++ and Visual Basic are trademarks of
Microsoft Corporation.

Borland is a registered trademark and Borland C++, Delphi, and Turbo Pascal are trademarks of
Borland International, Inc.

IBM is a registered trademark of International Business Machines Corporation.

Acrobat is a registered trademark of Adobe Systems Incorporated.

All other brand and product names are trademarks or registered trademarks of their respective
companies.

Copyright © Keithley Instruments, Inc., 1999, 1995.

All rights reserved. Reproduction or adaptation of any part of this documentation beyond that permitted
by Section 117 of the 1979 United States Copyright Act without permission of the Copyright owner is
unlawful.

S

The following safety precautions should be observed before using this product and any associated instrumentation.
Although some instruments 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

the equipment is operated within its specifications and operating limits, and for ensuring that operators are adequately
trained.

Operators

of the instrument. They must be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel

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 service personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation

Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most mea­surement, control, and data I/O signals are Installation Category I and must not be directly connected to mains voltage
or to voltage sources with high transient over-voltages. Installation 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 otherwise 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.

age 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 prevented access and/or insulated from every connection point. In some cases, connections must be ex­posed to potential human contact. 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,

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 connecting 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.

is the individual or group responsible for the use and maintenance of equipment, for ensuring that

use the product for its intended function. They must be trained in electrical safety procedures and proper use

perform routine procedures on the product to keep it operating properly, for example, setting

afety Precautions

A good safety practice is to expect that hazardous volt-

no conductive part of the circuit

5/02

When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main
input power disconnect device must be provided, in close proximity to the equipment 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 jumpers, 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 equipment may be impaired.

Do not exceed the maximum signal levels of the instruments and accessories, 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 con-

nections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation re-

quires the use of a lid interlock.

If or 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

WARNING

associated information very carefully before performing the indicated procedure.
The

CAUTION

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 selected 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 computer) 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/servicing.

heading in a manual explains dangers that might result in personal injury or death. Always read the

heading in a manual explains hazards that could damage the instrument. Such damage may invalidate

Table of Contents

Preface

1

Overview

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Supporting Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

2

Functional Description

Analog Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

Differential/Single-Ended Selection . . . . . . . . . . . . . . . . . . . .2-3

Ground Selection for Single-Ended Inputs . . . . . . . . . . . . . . . 2-4

Unipolar/Bipolar Selection . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

Channel-Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

Channel Expansion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Multiplexer Control Lines MUX 4 to MUX 7 . . . . . . . 2-5

External Gain Control Line GEXT . . . . . . . . . . . . . . . .2-6

Gains and Ranges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6

Maximum A/D Throughput Rates . . . . . . . . . . . . . . . . . . . 2-7

Data Conversion Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11

Clock Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12

Pacer Clock Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12

Burst Mode Conversion Clock. . . . . . . . . . . . . . . . . . . . . 2-13

Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14

Pre-Trigger Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16

About-Trigger Acquisition. . . . . . . . . . . . . . . . . . . . . . . . 2-16

Post-Trigger Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

Data Transfer Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18

Analog Output Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

Voltage Range Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20

Maximum D/A Throughput Rates . . . . . . . . . . . . . . . . . . . .2-20

Clock Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21

Triggers and Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-22

Data Transfer Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23

Digital I/O Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24

Using Digital Control Signal DOSTB . . . . . . . . . . . . . . . . .2-24

iii

Using Digital Control Signals TGOUT and TGIN . . . . . . . . 2-25

Using Digital Control Signal SSHO . . . . . . . . . . . . . . . . . . .2-26

Data Transfer Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27

Assigning an Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28

Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-28

3

Setup and Installation

Unwrapping and Inspecting a Board . . . . . . . . . . . . . . . . . . . . . . 3-1

Installing the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Installing the DAS-1800AO Series Standard Software

Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

Before Installing DriverLINX . . . . . . . . . . . . . . . . . . . . . . 3-3

Selecting the DriverLINX components to Install. . . . . . . . 3-3

Installing DriverLINX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Setting the Base Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Installing a Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

Configuring the DAS-1800AO Board with DriverLINX. . . . . . . 3-6

4

Cabling and Wiring

Attaching an STA-1800U. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Attaching an STP-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

Attaching an SSH-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6

Attaching an MB01 Backplane . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

Attaching MB02 Backplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

Attaching EXP-1800 Accessories . . . . . . . . . . . . . . . . . . . . . . . 4-10

Connecting Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11

Precautions for Using a DAS-1801AO Board at High

Gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

Additional Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

Connecting a Signal to a Single-Ended Analog Input. . . . . .4-13

Connecting a Signal to a Differential Analog Input . . . . . . . 4-13

Common Connection Schemes for Differential Inputs . . 4-13

Avoiding Ground Loops with Differential Inputs . . . . . . 4-15

Connecting Analog Output Signals. . . . . . . . . . . . . . . . . . . . 4-16

Connecting Digital I/O Signals. . . . . . . . . . . . . . . . . . . . . . . 4-16

Connecting Digital Control Signals . . . . . . . . . . . . . . . . . . . 4-16

Connecting and Synchronizing Multiple Boards . . . . . . . . . 4-17

iv

5

Testing the Board

DriverLINX Analog I/O Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

Test Panel Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

6

Calibration

Equipment Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Potentiometers and Test Points . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

DriverLINX Calibration Utility . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

7

Troubleshooting

Problem Isolation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Using the DriverLINX Event Viewer . . . . . . . . . . . . . . . . . . . 7-1

Device Initialization Error Messages . . . . . . . . . . . . . . . . . . . 7-2

Identifying Symptoms and Possible Causes . . . . . . . . . . . . . .7-2

Testing the Board and Host Computer . . . . . . . . . . . . . . . . . . 7-5

Testing the Accessory Slot and I/O Connections . . . . . . . . . . 7-5

Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-6

A

Specifications

B

Connector Pin Assignments

Main I/O Connector of DAS-1800AO Series Boards . . . . . . . . B-1

I/O Connectors J1 and J2 of the STA-1800U Accessory. . . . . . B-2

Connector J3 of the STA-1800U Accessory . . . . . . . . . . . . . . . B-3

Connectors J4 to J7 and Jumper Pads J8 to J11 of the

STA-1800U Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

C

DriverLINX Configuration Notes

Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

Calibrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

A/D Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

A/D Volts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

D/A Volts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

AI IRQ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

AI DMA 1, AO DMA 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

v

Special Device Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

Common-mode reference . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

Number of EXP-1800s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5

Simultaneous sample and hold configuration . . . . . . . . . . . . C-5

Disable AO recycle mode . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5

Implementation Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-6

Analog Input Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-8

Analog Input Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . C-8

Internal Clocking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9

Burst Mode Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9

Repeat Mode Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9

External Clocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

External Triggering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

External Gating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

Simultaneous Sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

Analog Input Multiplexer . . . . . . . . . . . . . . . . . . . . . . . . . . C-11

Data Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-13

A/D Conversion Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-14

A/D Data Lost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-14

Analog Output Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-15

Analog Output Initialization . . . . . . . . . . . . . . . . . . . . . . . . C-16

Internal Clocking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-16

Synchronous Analog Input/Output Clocking . . . . . . . . . . . C-16

External Clocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-17

External Triggering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-17

Data Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-17

D/A Conversion Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-18

D/A Data Lost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-19

Digital Input and Output Subsystems . . . . . . . . . . . . . . . . . . . C-20

Logical Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-20

Digital Input Initialization. . . . . . . . . . . . . . . . . . . . . . . . . . C-20

Digital Output Initialization . . . . . . . . . . . . . . . . . . . . . . . . C-21

Digital I/O Conversion Delay . . . . . . . . . . . . . . . . . . . . . . . C-21

Digital I/O Data Lost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-21

Counter/Timer Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-21

Counter/Timer Initialization . . . . . . . . . . . . . . . . . . . . . . . . C-22

Counter/Timer Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . C-22

vi

List of Figures

Figure 2-1. Block Diagram of

DAS-1800AO Series Boards . . . . . . . . . . . . . . . . . 2-2

Figure 2-2. Timing of A/D Conversion Modes

for a Queue of Channels 4 to 7 . . . . . . . . . . . . . . 2-12

Figure 2-3. Enabling Conversions with Software

Triggering/Gating and With

Internal and External Clocks . . . . . . . . . . . . . . . .2-15

Figure 2-4. Enabling Conversions with a

Hardware Trigger. . . . . . . . . . . . . . . . . . . . . . . . . 2-16

Figure 2-5. Hardware Gate. . . . . . . . . . . . . . . . . . . . . . . . . . .2-18

Figure 2-6. Timing Relationship between Data

from DO0 to DO3 and Latch Strobe DOSTB . . .2-25

Figure 2-7. Timing for the TGOUT Signal . . . . . . . . . . . . . . 2-26

Figure 2-8. Timing for SSHO Signal

When Not Used for SSH Hardware. . . . . . . . . . . 2-27

Figure 3-1. Location of Base Address Switch on

DAS-1800AO Series Boards . . . . . . . . . . . . . . . . . 3-5

Figure 4-1. Connector Layout of an STA-1800U Accessory. . 4-2
Figure 4-2. Cabling and Connections for Attaching an

STA-1800U to a DAS-1800AO Series Board. . . . 4-2

Figure 4-3. Pin Assignments for the Main I/O Connector

of a DAS-1800AO Series Board . . . . . . . . . . . . . . 4-3

Figure 4-4. Pin Assignments for Main I/O Connectors

J1 and J2 of the STA-1800U . . . . . . . . . . . . . . . . .4-4

Figure 4-5. Attaching an STP-50 to a

DAS-1800AO Series Board. . . . . . . . . . . . . . . . . . 4-5

Figure 4-6. Pin Assignments for Screw Terminals

of the STP-50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

Figure 4-7. Cabling and Connections for Attaching

an SSH-8 to a DAS-1800AO Series Board . . . . . .4-6

Figure 4-8. Attaching an MB01 Backplane to a

DAS-1800AO Series Board. . . . . . . . . . . . . . . . . . 4-7

Figure 4-9. Cabling and Connections for Attaching MB02

Backplanes to an STA-1800U . . . . . . . . . . . . . . . . 4-8

Figure 4-10. Daisy-Chaining STA-1800U Accessories with

Attached MB02 Backplanes . . . . . . . . . . . . . . . . . 4-9

Figure 4-11. Daisy-Chaining EXP-1800 Accessories . . . . . . . 4-10

Figure 4-12. Connections for Wiring a Signal Source to a

DAS-1800AO Series Board Configured for

Single-Ended Inputs. . . . . . . . . . . . . . . . . . . . . . . 4-13

vii

Figure 4-13. Three Types of Connections for Wiring a

Signal Source to a DAS-1800AO Series Board

Configured for Differential Inputs. . . . . . . . . . . . 4-14

Figure 4-14. A Differential Input Configuration that

Avoids a Ground Loop . . . . . . . . . . . . . . . . . . . .4-15

Figure 4-15. Differential Input Configuration with a

Ground Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

Figure 4-16. Two Connection Schemes for

Synchronizing Multiple Boards. . . . . . . . . . . . . . 4-17

Figure 6-1. Potentiometers and Test Points on the

DAS-1800AO Series Boards . . . . . . . . . . . . . . . . . 6-2

Figure B-1. Pin Assignments for the Main I/O Connector of a

DAS-1800AO Series Board. . . . . . . . . . . . . . . . . B-1

Figure B-2. Pin Assignments for Main I/O Connectors

J1 and J2 of the STA-1800U Accessory . . . . . . . B-2

Figure B-3. Pin Assignments for STA-1800U Connector J3 . B-3
Figure B-4. Pin Layouts and Assignments for STA-1800U

Connectors J4 to J7 and Jumper Pads J8 to J11. . B-4

List of Tables

Table 2-1. DAS-1801AO Gains and Ranges for

Unipolar and Bipolar Modes . . . . . . . . . . . . . . . . .2-6

Table 2-2. DAS-1802AO Gains and Ranges for

Unipolar and Bipolar Modes . . . . . . . . . . . . . . . . .2-6

Table 2-3. DAS-1800AO Series Board A/D Throughput for

Channel-to-Channel Sampling in Bipolar Mode

with Fixed Gain . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8

Table 2-4. DAS-1800AO Series Board A/D Throughput

for Channel-to-Channel Sampling in

Unipolar Mode with Fixed Gain . . . . . . . . . . . . . . 2-9

Table 2-5. Maximum A/D Throughput for

DAS-1801AO in Bipolar Mode. . . . . . . . . . . . . . . 2-9

Table 2-6. Maximum A/D Throughput for

DAS-1801AO in Unipolar Mode. . . . . . . . . . . . . 2-10

Table 2-7. Maximum A/D Throughput for

DAS-1802AO in Bipolar Mode. . . . . . . . . . . . . . 2-10

Table 2-8. Maximum A/D Throughput for

DAS-1802AO in Unipolar Mode. . . . . . . . . . . . . 2-11

Table 3-1. I/O Address Map (000H to 3FFH). . . . . . . . . . . . . 3-7

Table 7-1. Troubleshooting Information. . . . . . . . . . . . . . . . . 7-3

Table A-1. Analog Input Specifications . . . . . . . . . . . . . . . . A-1

Table A-2. Analog Output Specifications . . . . . . . . . . . . . . . A-4

viii

Table A-3. Digital I/O Specifications . . . . . . . . . . . . . . . . . . A-5

Table A-4. Power Supply Requirements . . . . . . . . . . . . . . . . A-6

Table C-1. Modes Supported by DAS-1800 Models. . . . . . . C-6

Table C-2. Allowed Operations and Events for

Supported Subsystem Modes. . . . . . . . . . . . . . . . C-7

Table C-3. Table of logical channel numbers for

eight external EXP-1800 Multiplexers. . . . . . . . C-12

ix

Preface

This guide is intended to help you understand the installation, interface
requirements, functions, and operation of the DAS-1801AO and
DAS-1802AO boards. Unless this guide refers specifically to the
DAS-1801AO or DAS-1802AO board, it refers to all boards collectively
as the DAS-1800AO Series boards. At the same time, the term

Series

refers to all members of the DAS-1800 family of data acquisition

boards.

This guide focuses primarily on describing the DAS-1800AO Series
boards and their capabilities, setting up the boards and their associated
software, making typical hookups, and operating the DriverLINX
software. There are also sections on calibration and troubleshooting. To
follow the information and instructions contained in this manual, you
must be familiar with the operation of an IBM PC or compatible in the
Windows 95/98 or Windows NT environment. You must also be familiar
with data acquisition principles and their applications.

The

DAS-1800AO Series User’s Guide

is organized as follows:

DAS-1800

●

Section 1 provides an overview of the features of DAS-1800AO
Series boards, including a description of supported software and
accessories.

●

Section 2 describes operating features of the boards in more detail.
This section contains a block diagram and brief descriptions of the
features as they relate to your options for setting up and using the
boards.

●

Section 3 contains instructions for inspection, software installation,
configuration, and board installation.

xi

Section 4 shows the preferred methods for making I/O (Input/Output)

●

connections, using the available accessories and cables.

●

Section 5 Briefly describes the DriverLINX Analog I/O program and
Test program.

●

Section 6 describes how to calibrate DAS-1800 Series boards.

●

Section 7 contains information on isolating and determining the
source of operating problems. This section also contains instructions
for obtaining technical support.

●

Appendix A lists the specifications for DAS-1800AO Series boards.

Appendix B lists the pin assignments for the main I/O connectors of

●

DAS-1800AO Series boards and for the connectors of DAS-1800
Series accessories.

Appendix C contains DriverLINX configuration information for the

●

DAS-1800 Series boards.

●

An index completes this manual.

xii

1

Overview

The DAS-1800AO Series boards are multi-function data acquisition
boards that operate with DriverLINX software that requires:

an IBM PC or compatible AT (386 or Pentium CPU) with minimum

●

of 2 MB of memory.

●

at least one CD ROM drive, one fixed disk drive, and one floppy disk
drive.

●

Microsoft Windows 95/98 or Windows NT 4.0 or higher.

●

a compiler supporting Microsoft Windows development.
a mouse is highly recommended.

●

The DAS-1801AO is a 12-bit, high-gain board, while the DAS-1802AO is
a 12-bit, low-gain board. This section describes features, supporting
software, and accessories of the DAS-1800AO Series boards.

Features

Analog input features of the DAS-1800AO Series boards are as follows:

●

The board acquires data at up to 333 ksamples/s with 12-bit
resolution.

●

The board is software-configurable for 16 single-ended or 8
differential onboard channels or up to 256 differential channels using
expansion accessories.

●

Channels are individually software-configurable for gain.

●

A 1024-location FIFO (First In First Out) data buffer ensures data
integrity at all sampling rates.

Features 1-1

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 real-time simultaneous-sample-and-hold
capability.

●

Data transfer modes include single- or dual-channel DMA, interrupt,
or programmed I/O.

DMA and interrupt levels are software-selectable.

●

●

The polarity of hardware trigger and gate for A/D (analog-to-digital)
conversions is software-selectable.

A/D triggering supports pre-, post-, and about-trigger acquisitions.

●

Analog output features of the DAS-1800AO Series boards are as follows:

●

Analog output is available through two, 12-bit, deglitched DACs
(digital-to-analog converters).

●

Each DAC converts up to 500 ksamples/s.

●

DAC output ranges are ±5V and ±10V.
The DACs are supported by a 2048-word data FIFO.

●

●

The DACs can be updated individually or simultaneously.

●

At power-up, the DAC outputs are 0V.
The polarity of hardware trigger and gate for D/A (digital-to-analog)

●

conversions are software-selectable.

●

The analog output section can perform recycle-mode waveform
generation using the onboard FIFO.

●

The DACs can be updated by DMA, interrupt, or programmed I/O
transfers.

Digital I/O features of the DAS-1800AO Series boards are as follows:

The boards have four digital inputs.

●

●

The boards have four digital outputs with a latch strobe.

1-2 Overview

General features of the DAS-1800AO Series boards are as follows:

●

Pulsed interrupts allow multiple DAS-1800 Series boards to share
interrupt levels.

All user connections are made through a 50-pin I/O connector at the

●

rear panel of the computer.

●

All features are software-programmable except for a board’s base
address switch.

●

The boards provide ±15V power for accessories and external
circuitry.

Interrupt levels (levels 3, 5, 7, 10, 11, and 15) are software-selectable.

●

●

The boards use burst demand mode DMA for increased data transfer
throughput.

The boards make 16-bit data transfers on the AT bus.

●

For more information on these features refer to Section 2, Functional
Description.

Supporting Software

DAS-1800AO Series standard software package

●

— Shipped with
DAS-1800AO Series boards. Includes DriverLINX for Microsoft
Windows 95/98 or Windows NT and function libraries for writing
application programs under Windows in a high-level language such as
Microsoft Visual C++, Microsoft Visual Basic, Borland Delphi
support files, LabVIEW, utility programs, and language-specific
example programs.

●

DriverLINX —

the high-performance real-time data-acquisition

device drivers for Windows application development includes:

DriverLINX API DLLs

–

and drivers supporting the DAS-1800AO

Series hardware.

Analog I/O Panel —

–

A DriverLINX program that verifies the
installation and configuration of DriverLINX to your
DAS-1800AO Series board and demonstrates several virtual
bench-top instruments.

Supporting Software 1-3

–

Learn DriverLINX —

an interactive learning and demonstration
program for DriverLINX that includes a Digital Storage
Oscilloscope.

–

Source Code —
DriverLINX Application Programming Interface files —

–

for the sample programs.

application programming interface files for the DAS-1800AO
Series.

Accessories

LabVIEW support for DriverLINX —

–

application programming

interface files for the DAS-1800AO Series.

DriverLINX On-line Help System —

–

provides immediate help as

you operate DriverLINX.

Supplemental Documentation —

–

on DriverLINX installation and
configuration, analog and digital I/O programming, counter/timer
programming, technical reference, and information specific to the
DAS-1800AO Series hardware.

DAS-1800AO Series utilities —

●

The following utilities are provided

as part of both the DAS-1800AO Series standard software packages:

Analog I/O Utility —

–

DriverLINX utility used for data acquisition

and testing board operation.

Test Utility —

–

DriverLINX utility used for testing board

operation.

Calibration Utility —

–

DriverLINX utility used for calibration.

The following accessories are available for use with DAS-1800AO Series
boards:

STA-1800U

●

— screw terminal accessory. This accessory connects to
the main I/O connector of a DAS-1800AO Series board through a
CDAS-2000 cable to make all I/O signals accessible through labeled
screw terminals.

●

STP-50

— screw terminal panel. This accessory provides
general-purpose screw-terminal connections in a compact form
factor.

1-4 Overview

SSH-8

●

— An 8-channel simultaneous-sample-and-hold accessory for
the DAS-1800AO Series boards. Refer to the
more information.

SSH-8 User’s Guide

for

MB Series modules and MB01/02 backplanes

●

signal-conditioning modules and backplanes. Refer to the

User’s Guide

EXP-1800

●

for more information.

— A 16-channel expansion accessory that connects

directly to DAS-1800AO Series boards. Refer to the

User’s Guide

C16-MB1

●

for more information.

— A cable with a 37-pin, female, D-type connector and a

— Plug-in, isolated,

MB Series

EXP-1800

26-pin, female header connector for connecting an STA-1800U to an
MB01 backplane.

●

C-2600

— An 18-inch ribbon cable for connecting an STA-1800U to

an MB02 backplane.

●

C-1800

— An 18-inch ribbon cable with two 37-pin female type D

connectors for connecting an STA-1800U to an SSH-8.

●

CDAS-2000 Series

— The CDAS-2000 is a 24-inch ribbon cable for
connecting a DAS-1800AO Series board to an STA-1800U, an
STP-50, or an EXP-1800. The SDAS-2000 is a 24-inch shielded
version of the CDAS-2000.

●

CAB-50 Series

— A cable you use to form a daisy chain of
EXP-1800s; this cable is available in two lengths, as follows: the
CAB-50 is 4 inches long, and the CAB-50/1 is 18 inches long.

●

CACC-2000

— A 24-inch ribbon cable for daisy chaining additional
STA-1800U accessories to the first STA-1800U or additional
EXP-1800 accessories to the first EXP-1800.

Accessories 1-5

2

Functional Description

This section describes the features of the analog input, analog output, and
digital I/O sections of the DAS-1800AO Series boards. These
descriptions are provided to familiarize you with the operating options
and to enable you to make the best use of your board. Figure 2-1 shows
the block diagram of the DAS-1800AO Series boards.

2-1

CH 0/0

Analog

Inputs:

8 Diff.

or 16

CH 7/15

GEXT

MUX [7:4]

U_CM_MD

LL GND

DAC 0

DAC 1

Uni./Bip. Select

8 or 16

CM_MD

Inst.

Sampling

12-Bit ADC

1K x 16

A/D FIFO

Channel

Input MUX

Gain

• ADC Timing and Control

Diff./S.E.

• Interrupt Control

• ADC DMA Control

• Burst Mode Control

256 x 11

Chan.-Gain

Internal Bus

Amplifier

Sample

12-Bit

DAC 0

• DAC Timing and Control

Range Select

Range Select

• 16-Bit D/A Counter

• DAC DMA Control

Amplifier

Sample

12-Bit

DAC 1

• Recycle Mode Control

2048 x 16

Buffer

ISA AT Bus

Figure 2-1. Block Diagram of DAS-1800AO Series Boards

D GND

+5V

+5V

5V Ret.

+15V

–15V

DC/DC

+15V

15V Ret.

–15V

+5V

82C54 Counter/Timer

• 32-Bit A/D Counter

Buffe

SSHI

• About-Trigger Counter

SSHO

TGIN

TGOUT

Buffe

r

XPCLK

DI [3:0]

r

DOSTB

Latch

DO [3:0]

2-2 Functional Description

Analog Input Features

The analog input section of a DAS-1800AO 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 12 bits (one part in 4096). Other features of the
analog input section include software-configurable inputs, a channel-gain
queue, data conversion modes, clock sources, trigger and gate control,
and data transfer modes. These features are described in the following
subsections.

Differential/Single-Ended Selection

Using DriverLINX software, you can set DAS-1800AO Series boards to
operate at either differential or single-ended inputs (see “DriverLINX
Configuration Notes” on page C-1). Differential inputs measure the
difference between two signals. Single-ended inputs are referred to a
common ground, also called

When you connect single-ended inputs to a DAS-1800AO Series board,
you can use the board’s LL GND (analog ground) or U_CM MD
(user-common mode) connections for your common-mode ground
reference. You specify your choice using DriverLINX (see “DriverLINX
Configuration Notes” on page C-1).

common-mode ground reference.

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 100mV and below.

Analog Input Features 2-3

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 schemes differ in how the low side of the instrumentation amplifier is
connected. In the default mode, the low side of the amplifier is connected
to analog ground (LL GND). In the user-common mode, the low side of
the amplifier is connected to a pin on the connector for user-common
ground (U_CM MD).

The user-common mode provides a means for 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 pin connects to 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
measurements of 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 20mA current monitoring is to connect a loop with a 250
resistor to ground; the resistor yields a 1 to 5V output in this current
range. This method works but uses only 80% of the input range when
connected to a 0 to 5V range. A better way is to use a 312.5
refer all measurements to 1.25V. The actual output voltage then ranges
from 1.25V to 6.25V; however, since the amplifier low side is connected
to 1.25V, the measurement range is now a span of 5V, making the entire
input range available and increasing resolution of the measurements by
20%.

Ω

resistor and

Ω

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 separate wire for low input.

Unipolar/Bipolar Selection

Using DriverLINX, you can set the DAS-1800AO Series boards to
operate in either unipolar or bipolar input mode (see “DriverLINX
Configuration Notes” on page C-1). A unipolar signal is always positive
(0 to 5V, for example), while a bipolar signal can swing up and down
between positive and negative peak values (±5V, for example).

2-4 Functional Description

The DAS-1800AO Series boards use positive magnitude to represent
unipolar signals and 2’s complement for bipolar signals. When the input
range offers the same peak-voltage capacity for unipolar or bipolar
modes, the unipolar mode doubles the converter’s resolution.

Channel-Gain Selection

The DAS-1800AO Series boards offer up to 16 single-ended or 8
differential onboard analog input channels. Using EXP-1800 expansion
accessories, you can increase the number of inputs to 256, which are
differential only. To accommodate channel and gain settings for up to 256
inputs, the DAS-1800AO Series boards contain a RAM storage circuit for
a 256-position channel-gain queue. Each of the 256 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. Channel expansion, channel sequencing control, and
available gains and input ranges for DAS-1800AO Series boards are
discussed in the following subsections.

Channel Expansion

If you require additional analog input channels, you can configure your
DAS-1800AO Series board for single-ended inputs and attach up to 16
EXP-1800 expansion accessories or up to 16 MB02 backplanes. Either
option can increase your input capacity to 256.

If you use MB02 backplanes, use one STA-1800U for every four
backplanes. Connect each group of four backplanes to an STA-1800U, as
shown in Section 4, and daisy-chain any additional STA-1800U
accessories to the first STA-1800U.

Sampling sequences and gain settings for all expansion-board channels
are communicated through the control lines described in the following
two subsections.

Multiplexer Control Lines MUX 4 to MUX 7

Multiplexer lines MUX 4 to MUX 7 control the channel sequencing of
EXP-1800 and MB01/02 expansion accessories. These lines carry the
channel-sequencing information from the channel-gain QRAM through
the main I/O connector of DAS-1800AO Series boards.

Analog Input Features 2-5

External Gain Control Line GEXT

External gain line GEXT sets channel gains on EXP-1800 accessories to
1 or 50. This line carries the channel-gain settings from the channel-gain
QRAM through the main I/O connector of the DAS-1800AO Series
boards.

Gains and Ranges

The available gains and their corresponding input ranges are listed in
Table 2-1 for the DAS-1801AO and Table 2-2 for the DAS-1802AO.

Table 2-1. DAS-1801AO Gains and Ranges for Unipolar and

Bipolar Modes

Gain Unipolar Range Bipolar Range

1 0 to 5V –5.0 to +5.0V

5 0 to 1V –1.0 to +1.0V

50 0 to 100mV –100 to +100mV

250 0 to 20mV –20 to +20mV

Table 2-2. DAS-1802AO Gains and Ranges for Unipolar and

Bipolar Modes

Gain Unipolar Range Bipolar Range

1 0.0 to +10.0V –10 to +10V

2 0.0 to +5.0V –5.0 to +5.0V

4 0 to 2.5V –2.5 to + 2.5V

8 0 to 1.25V –1.25 to +1.25V

2-6 Functional Description

Maximum A/D Throughput Rates

Because you can change input ranges on a per-channel basis, throughput
may drop if you group channels with varying gains in sequence. The drop
occurs because the channels with low-level inputs (magnitude of 100mV
or less) are slower than those with high-level inputs and because the
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 external signal
conditioning. When using the channel-gain queue, consider the following
suggestions:

●

Keep all 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 ±5V or 0 to
5V. This method offers the advantages of increasing total system
throughput and reducing noise.

●

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.

●

If you are measuring steady-state signals, do not use the channel-gain
queue. Instead, use software to step through the channels and perform
single-channel acquisitions. For example, use software-controlled,
single-channel acquisitions to acquire 1000 samples on channel 0 at a
gain of 1 and then 2000 samples on channel 1 at a gain of 250 to
virtually eliminate interference. This method is the best for measuring
steady-state signals even if all the channels are at the same gain.

You must give special consideration to the direct measurement of
low-level signals with the DAS-1801AO board. When using the ±20mV,
0 to 20mV, ±100mV, or 0 to 100mV ranges, measurement throughput
drops for two reasons:

The amplifier needs more time to settle to rated accuracy when

●

switching to a high gain.

●

Noise in the measurements is higher and thus can require
post-acquisition filtering (averaging) to achieve accurate results.

Analog Input Features 2-7

The DAS-1801AO has best noise performance if presented with a perfect
signal in these ranges, but perfect signals are virtually nonexistent in the
real world. Since the DAS-1801AO has very high bandwidth (bandwidth
for low-level signals is about 8 to 10MHz) any noise is amplified and
digitized. As a result, you must carry out the measurement of low-level
signals carefully to minimize noise effects.

Low-level transducers are best used with signal conditioning. Use the
±20mV, 0 to 20mV, ±100mV, and 0 to 100mV ranges with the differential
input mode.

The tables that follow 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 the source 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

–

20mV is
measured after a signal at near +5V. 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

Ω

(1kΩ

maximum) in series with 90pF output capacitance.

On DAS-1800AO 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.

Table 2-3. DAS-1800AO Series Board A/D Throughput for Channel-to-Channel

Sampling in Bipolar Mode with Fixed Gain

DAS-1801AO Input Range DAS-1802AO Input Range Throughput

— ±10.0V 312.5 ksamples/s

±5.00V ±5.00V 312.5 ksamples/s

— ±2.50V 312.5 ksamples/s

— ±1.25V 312.5 ksamples/s

±1.00V — 312.5 ksamples/s

±100mV — 312.5 ksamples/s

±20mV — 75 ksamples/s

2-8 Functional Description

The throughput for channel-to-channel sampling with fixed gain in
unipolar mode (0.024% maximum error) is shown in Table 2-4.

Table 2-4. DAS-1800AO Series Board A/D Throughput for Channel-to-Channel

Sampling in Unipolar Mode with Fixed Gain

DAS-1801AO Input Range DAS-1802AO Input Range Throughput

— 0 to 10.0V 312.5 ksamples/s

0 to 5.00V 0 to 5.00V 312.5 ksamples/s

— 0 to 2.50V 312.5 ksamples/s

— 0 to 1.25V 312.5 ksamples/s

0 to 1.00V — 312.5 ksamples/s

0 to 100mV — 250 ksamples/s

0 to 20mV — 60 ksamples/s

The maximum throughput for a DAS-1801AO 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 A/D Throughput for DAS-1801AO in Bipolar Mode

Maximum Throughput

To ±5V To ±1.0V To ±100mV To ±20mV

From ±5.0V
From ±1.0V
From ±100mV
From ±20mV

Analog Input Features 2-9

312.5 ksamples/s 250 ksamples/s 200 ksamples/s 70 ksamples/s

250 ksamples/s 312.5 ksamples/s 312.5 ksamples/s 70 ksamples/s

200 ksamples/s 312.5 ksamples/s 312.5 ksamples/s 70 ksamples/s

70 ksamples/s 70 ksamples/s 70 ksamples/s 75 ksamples/s