Omega Products OMB-DBK Installation Manual

January 2002

OMB - DBK Option Cards

& Modules User’s Manual

p/n

OMB-457-0905

Rev

1.0

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The information contained in this document is believed to be correct but OMEGA Engineering, Inc. accepts
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WARNING:

These products are not designed for use in, and should not be used for, patient-connected applications.

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Manual Layout

The DBK Option Cards and Modules User’s Manual (457-0905) is a companion document to other user’s
manuals, e.g., the DaqBook/DaqBoard [ISA]/ Daq PC-Card User’s Manual (457-0901), the

DaqBoard/2000 Series and cPCI DaqBoard/2000c User’s Manual (1033-0901), and the LogBook User’s
Manual (461-0901).

This user’s manual includes several chapters and a document module for each DBK. Document modules
are like chapters, except they are shared by other documents and are sometimes used as stand-alone
documents. For these reasons, the document modules do not contain chapter headings.

Chapters

– Introduction to DBKs. Explains what DBKs are and uses tables to identify the various types of

1

– Power Management. Explains how to determine system power requirements and discusses various

2

– System Connections and Pinouts. Provides instructions for connecting a DBK option to a Daq or

3

– DBK Set Up in DaqView. Provides instruction for setting up analog and digital DBKs in

4

DBKs. The chapter includes: tips for setting up a data acquisition system, discussions of signal
management and signal conditioning, and CE compliance information.

power options.

LogBook device. Pinouts are included for the P1, P2, and P3 DB37 connectors, as well as the 100­pin P4 connector used by PCI and compact PCI (cPCI) boards.

DaqView’s Hardware Configuration screen.

– DBK Set Up in LogView. Provides instruction for setting up analog and digital DBKs in

5

LogView’s Hardware Configuration window.

– Troubleshooting. Explains solutions to common noise, wiring, and configuration problems.

6

DBK Document Modules -

Refer to the Table of Contents for a complete list.

Reference Notes:

Refer to the following documents as applicable for acquisition system or programming information that is
related to use of DBK option cards and modules.

•

DaqBook/DaqBoard [ISA]/ Daq PC-Card User’s Manual (p/n 457-0901)

•

LogBook User’s Manual (p/n 461-0901)

•

Programmer’s Manual (p/n 1008-0901)

•

Post Acquisition Data Analysis User’s Guide(s)

Note: During software installation, Adobe

hard drive as a part of product support. The default location is in the Programs directory, which can be
accessed from the Windows Desktop. Refer to the PDF documentation for details regarding both
hardware and software.

A copy of the Adobe Acrobat Reader
and printing the PDF documents. Note that hardcopy versions of the manuals can be ordered from the
factory.

The DBK document modules are provided in alphanumeric order.

®

PDF versions of user manuals will automatically install onto your

®

is included on your CD. The Reader provides a means of reading

DBK Option Cards & Modules User’s Manual

01-22-02

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01-22-01

DBK Option Cards & Modules User’s Manual

Table of Contents

Chapters

1 – Introduction to DBKs

What are DBKs?…… 1-1
How do DBKs Connect to the Data

Acquisition Device? ….. 1-2
DBK Identification Tables …… 1-5
Tips on Setting up a Data Acquisition

System……1-7
Signal Management …… 1-8
Using DBK Cards and Modules for Signal

Conditioning……1-13
Channel Control and Expansion……1-14
Signal Acquisition …… 1-16
Two-Point Calibration of a Temperature

Measurement System …… 1-19
CE Compliance …… 1-22

2 – Power Management

An Introduction to Power-Related DBKs…2-1
Power Requirements ……2-2
Calculating Your System’s Power Needs

……2-3
Power Supplies and Connectors ……2-5

3 – System Connections and Pinouts

Overview …… 3-1
DaqBook …… 3-1
DaqBoard (ISA Type) …… 3-2
Daq PC-Card……3-2
LogBook ….. 3-3
DaqBoard/2000 Series and

cPCI DaqBoard/2000c Series……3-2

4 – DBK Set Up in DaqView

Overview …… 4-1
Setting Up Analog DBKs …… 4-3
Setting Up Digital DBKs …… 4-5

Setting Internal Clock Speed to 100 kHz …4-7

5 – DBK Set Up in LogView

Overview …… 5-1
Setting Up Analog DBKs …… 5-3

Setting Up Digital DBKs …… 5-6

6 – Troubleshooting

ESD Handling Notice …… 6-1
Troubleshooting Checklist……6-1
Frequently Asked Questions ……6-3
Customer Assistance……6-6

Document Modules

DBK1

,

16-Connector BNC Adapter Module

DBK2

,

4-Channel Voltage Output Card

DBK4,
DBK5,
DBK7
DBK8
DBK9,
DBK10,
DBK11A,
DBK12 and DBK13,
DBK15,
DBK16,
DBK17,

DBK18,
DBK19,
DBK20 and DBK21,
DBK23,
DBK24,
DBK25,
DBK30A,
DBK32A,
DBK33,
DBK34,
DBK34A,
DBK40,
DBK41,
DBK42,
DBK43A,
DBK44,
DBK45,
DBK50 and DBK51
DBK52,
DBK53 and DBK54,
DBK60,
DBK80

DBK81
DBK82
DBK83

DBK84
DBK601 thru DBK609,

2-Channel Dynamic Signal Input Card
4-Channel Current Output Card

,

4-Ch. Frequency-To-Voltage Input Card

,

8-Channel High-Voltage Input Card

8-Channel RTD Card

3-Slot Expansion Chassis

Screw-Terminal & BNC Option Card

A/I Multiplexer Cards
Universal Current, Voltage Input Card
2-Channel Strain-Gage Card
4-Channel Simultaneous Sample and

Hold Card

4-Channel, Low-Pass Filter Card
14-Channel Thermocouple Card

Digital I/O Cards
Isolated Digital Input Chassis

Isolated Digital Output Chassis

8-Channel Relay Output Card

Rechargeable Battery Module

Auxiliary Power Supply Card

Triple-Output Power Supply Card

Vehicle UPS Module

UPS / Battery Module
18-Connector BNC Analog Interface
10-Slot Expansion Module
16-Slot 5B Signal Conditioning Module

8-Channel Strain-Gage Module

2-Ch. 5B Signal-Conditioning Card

4-Ch. SSH and Low-Pass Filter Card

, Voltage Input Modules

14-Ch. Thermocouple Input Module

Analog Multiplexing Modules

3-Slot Expansion Chassis

, 16-Ch. Differential Voltage Input Card

with Excitation Output

, 7-Ch. T/C Card, High Accuracy
, 14-Ch. T/C Card, High Accuracy
, 14-Ch. T/C Card, High Accuracy, uses

external connection pod

, 14-Ch. T/C Module, High Accuracy

Termination Panels

DBK Option Cards & Modules User’s Manual

01-22-02

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01-22-02

DBK Option Cards & Modules User’s Manual

Introduction to DBKs 1

What are DBKs?…… 1-1
How Do DBKs Connect to the Data Acquisition Device? …… 1-2

Connecting DBKs to DaqBooks, ISA-Type DaqBoards, and LogBooks …… 1-2
Connecting DBKs to Daq PC-Cards …… 1-3
Connecting DBKs to DaqBoard/2000 Series and cPCI DaqBoard/2000c Series Boards …… 1-4

DBK Identification Tables ….. 1-5

Analog Output DBKs …… 1-5
Digital I/O Control DBKs …… 1-5
Analog Signal Conditioning DBKs …… 1-5
Expansion and Terminal Panel Connection DBKs …… 1-6
Power Supply DBKs …… 1-6

Tips on Setting up a Data Acquisition System …… 1-7
Signal Management …… 1-8
Using DBK Cards and Modules for Signal Conditioning ….. 1-13
Channel Control and Expansion …… 1-14
Signal Acquisition …… 1-16
Two-Point Calibration of a Temperature Measurement System …… 1-19
CE Compliance …… 1-22

What are DBKs?

The term “DBK” typically refers to a card or module that is used to expand or enhance a primary data
acquisition device. As can be seen from the DBK identification tables in the section that follows, DBKs
provide a wide variety of data acquisition functions. Depending on the DBKs used, one or more of the
following can be realized:

•

signal conditioning

•

analog output

•

digital I/O

•

channel expansion

•

supplying powering to another acquisition device

•

providing an interface for different connectivity; for example:
changing from a 100-pin P4 connector to three 37-pin DB37 connectors.

This manual is dedicated to DBK options and includes information regarding installation, configuration,
and power management for typical DBK applications. The specifics for each DBK are discussed in their
respective document module. These are presented alphanumerically for ease of reference. Note that the
footers include DBK identification next to the page number.

The specific DBK document modules usually contain the following elements:

•

Overview (usually with a block diagram) describes the basic features and operation of the DBK.

•

Hardware Setup describes configuration and connections for both the DBK and primary
acquisition device, e.g., DaqBook, DaqBoard, LogBook.

•

Hardware Function describes special hardware concerns if beyond the scope of the Overview.

•

Specifications

DBK Option Cards and Modules

Reference Notes:

➣

DBK setup in DaqView is discussed in chapter 4.

➣

DBK setup in LogView is discussed in chapter 5.

01-17-02

Introduction to DBKs 1-1

How Do DBKs Connect to the Data Acquisition Device?

Each DBK connects to the primary data acquisition device through one of three 37-pin ports, which are
designated as follows:

•

P1 – Analog I/O

•

P2 – Digital I/O

•

P3 – Pulse/Frequency/High-Speed Digital I/O

Depending on the primary data acquisition device, connectivity issues differ slightly. This will be made
clear by the three figures that follow and the accompanying text.

Connecting DBKs to DaqBooks, ISA-Type DaqBoards, and LogBooks

For DaqBooks, ISA-Type DaqBoards, and LogBooks, DBK connections are not made directly to the port,
but through a CA-37-x ribbon cable, where “x” indicates the number of expansion devices that can be
connected. For example, in addition to providing a DB37 connector to interface with the primary data
acquisition device, a CA-37-3 cable includes three additional DB37 connectors. These provide a means of
adding three DBKs to one port. Use of a CA-37-16 cable will allow up to 16 DBKs to be added. The
CA-37-x cable system is excellent for DaqBooks, LogBooks, and ISA-type DaqBoards.

The above figure applies to LogBooks, DaqBooks, and ISA-type DaqBoards. As will be seen elsewhere in
the documentation, some models do not include all three connectors (P1, P2, and P3).

1-2 Introduction to DBKs

Connecting DBKs to a DaqBook

01-17-02

DBK Option Cards and Modules

Connecting DBKs to Daq PC-Cards

The Daq PC-Card is only intended for connections to a P1 connector of a single “passive” DBK card or
module. A passive DBK card or module is one that provides a desired connectivity (such as BNCs or screw
terminals), but performs no signal conditioning.

A CA-134 Interface Cable and a CN-86-F (dual DB37 female adapter) are used to provide the DB37 P1
connector.

Daq PC-Card Cabling

The CA-134 cable connects to a CN-86-F adapter, which then connects to a single “passive” card or
module. The passive DBKs are:

•

DBK1 – 16 Connector BNC Module

•

DBK11A – Screw Terminal Option Card

•

DBK40 – BNC Analog Interface

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-3

Connecting DBKs to DaqBoard/2000 Series and cPCI DaqBoard/2000c Series Boards

DaqBoard/2000 Series and cPCI DaqBoard/2000 Series boards have 100-pin connectors designated as P4.
The 100 pins correlate to various pins on P1, P2, and P3 DB37 connectors.* Connectivity in the system is
as follows (see figure).

•

The /2000 Series or /2000c Series board connects to a CA-195 cable [which has two 100-pin
P4 connectors].

•

The CA-195 connects to a DBK200 Series adapter board or adapter module for 100-pin to
37-pin adaptations, i.e., P4-to-P1, P2, P3; but not necessarily all three.*

•

The DBK200 Series adapter connects to a CA-37-x ribbon cable, where “x” indicates the
number of expansion devices that can be connected. For example, in addition to providing a
DB37 connector to interface with the primary data acquisition device, a CA-37-3 cable
includes three additional DB37 connectors. These provide a means of adding three DBKs to
one port. Use of a CA-37-16 cable will allow up to 16 DBKs to be added.

•

The CA-37-x cable connects to expansion DBKs, in accordance with port type. For example,
Analog DBKs to port P1, Digital DBKs to port 2, and passive DBKs to port 3.

* DaqBoard/2003 and cPCI DaqBoard/2003c are exceptions to the above connectivity method. The /2003

boards typically connect directly to a DBK205 (P4-to-Screw Terminal Adapter), as discussed elsewhere.

1-4 Introduction to DBKs

Connecting DBKs to a DaqBoard/2000 Series Board

01-17-02

DBK Option Cards and Modules

DBK Identification Tables

Analog Output DBKs

Analog Output

Product Name/Description I/O

DBK2 Voltage Output Card 4 channels P1
DBK5 Current Output Card 4 channels P1

Digital I/O Control DBKs

Digital I/O / Control

Product Name/Description I/O

DBK20 General-Purpose Digital I/O Card (Screw Terminals) 48 channels P2
DBK21 General-Purpose Digital I/O Card (DB 37 Connectors) 48 channels P2
DBK23 Optically Isolated Digital-Input Module 24 channels P2
DBK24 Optically Isolated Digital-Output Module 24 channels P2
DBK25 Relay Output Card 8 channels P2
DBK208 Carrier board f or Opto-22 Compatible Solid-State-Relay

Digital Modules.

Analog Signal Conditioning DBKs

The DBKs that are used for analog signal conditioning attach to transducers and condition their outputs into
analog voltages. An A/D converter, located in the primary acquisition device, measures the analog
voltages. There are many signal-conditioning solutions available (and more are in development). Note that
DBK high-capacity modules require more circuitry than can fit on a compact card.

Two 8-bit banks of
SSR modules

Conectivity

Conectivity

Two P2s

P4

Analog Signal Conditioning

Product Name/Description I/O

DBK4 Dynamic Signal Input Card 2 channels P1
DBK7 Frequency-to-Voltage Input Card 4 channels P1
DBK8 High-Voltage Input Card 8 channels P1
DBK9 RTD Measurement Card 8 channels P1
DBK12 Low-Gain Analog Multiplexing Card
DBK13 High-Gain Analog Multiplexing Card
DBK15 Universal Current/Voltage Input Card
DBK16 Strain-Gage Measurement Card 2 channels P1
DBK17 Simultaneous Sample & Hold Card 4 channels P1
DBK18 Low-Pass Filter Card 4 channels P1
DBK19 Thermocouple Card
DBK42 5B Isolated Signal-Conditi oni ng Module 16 channels P1
DBK43A Strain-Gage Measurement Module 8 channels P1
DBK44 5B Isolated Signal-Conditi oni ng Card 2 channels P1
DBK45 SSH and Low-Pass Filter Card 4 channels P1
DBK50 Isolated High-Voltage Input Module 8 channels P1
DBK51 Isolated Low-Voltage Input Module 8 channels P1
DBK52 Thermocouple Input Module
DBK53 Low-Gain Analog Multiplexing Module
DBK54 High-Gain Analog Multiplexing Module

DBK70 Vehicle Net work I nterface, Analog Multiplexer Module 16 channels P1

DBK80 Differential Voltage Input Card with Excitation Output 16 channels P1
DBK81 Thermocouple Card, High-Acc uracy 7 channels P1
DBK82 Thermocouple Card, High-Acc uracy 14 channels P1
DBK83 Thermal Couple Card, High-Accuracy; uses Connection Pod 14 channels POD-1
DBK84 Thermocouple Module, High-Accuracy 14 channels P1
DBK207 Carrier B oard for 5B Compatible Analog Input Modules 16 channels Two P1s / P4
DBK207/CJC Carrier Board for 5B Compatible A nal og Input Modules.

Note 1

Note 2

DBK207/CJC includes c ol d junction compensation (CJC)

P1, P2, and P3 DB37 connect ors do not exist on the DaqBoard/2000 Series or /2000c Seri es boards,

:

but are obtained by using P4 adapters (DBK200 series). These adapters typically connect to the
DaqBoard/2000 Series [/2000c S eri es] 100-pin P4 connector via a CA-195 cable.

For DaqBoard/2000 and cPCI DaqBoard/2000 Series boards, internal clocks should be set to 100 kHz

:

when used with any of the following DBK options: DBK12, DBK13, DBK15, DBK19, DB K 52, DBK53,
and DBK54. See specific DBK section for details.

Note 2
Note 2
Note 2

Note 2

Note 2
Note 2
Note 2

16 channels P1
16 channels P1
16 channels P1

14 channels P1

14 channels P1
16 channels P1
16 channels P1

16 channels Two P1s / P4

Connectivity

1

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-5

Expansion and Terminal Panel Connection DBKs

The following DBKs offer provide various expansion and connection options. The stackable 3-slot DBK10
low-profile enclosure can be used for up to three DBKs. If a system has more than 3 DBKs, the 10-slot
DBK41 can be used. Several DBK41s can be daisy-chained to accommodate many DBKs in one system.

Expansion and Connection, General

Product Name/Description I/O

DBK1 16-Connector BNC Adapter Module 16 connectors P1
DBK10 3-Slot Expansion Chassis 3 cards P1, P2, or P3
DBK11A Screw-Terminal Option Card (DB37-Screw Terminal Block) Component

DBK40 BNC Interface 18 connectors P1 or P3
DBK41 Analog Expansion Enclosure 10 cards P1 or P2
DBK60 Expansion Chassis with Terminati on Panels 3 cards P2

Connectivity

P1

sockets

Termination Panels, Connectivity for DaqBoard/260

Product Name/Description I/O

DBK601 Termination Panel - blank rear panel none none
DBK602 Termination Panel - BNC rear panel 16 connectors BNC
DBK603 Termination Panel - Safety Jacks, single ended 16 connectors Safety Jacks
DBK604 Termination Panel - Safety Jacks, differential 8 differential (16) Safety Jacks
DBK605 Termination Panels - Thermal Couple, differential panels;

specify type: B, J, K, R, S, or T

DBK606 Termination Panel – 3 Terminal Blocks; 16 connections per TB 48 connectors Screw Terminal
DBK607 Termination Panel – strain relief clamp none none
DBK608 Termination Panel – 3 female DB37 connec tors three DB37 DB37

16 differential T/C Connectors

Connectivity

1

Several signal connection options were developed primarily for use with DaqBoard/2000 Series and
cPCI DaqBoard/2000c Series Boards. The DBK200 Series P4-Adapter documentation provides the basic
connection concepts. That information, along with the related DBK subsections should enable you to set up
your desired configuration.

P4 Adaptive Connection for DaqBoard/2000 Series and cPCI DaqBoard/2000c Series

Product Name/Description I/O

DBK200 P4-to-P1 Adapter Board P1 P4
DBK201 P4-to-P1/P2/P3 Adapter Board P1, P2, P3 P4
DBK202 P4-to-P1/P2/P3 Adapter Board with Screw-Terminals P1, P2, P 3 P4
DBK203 A module version of DBK202 P1, P2, P3 P4
DBK204 A module version of DBK202 with an included CE c abl e kit. P1, P2, P3 P4
DBK205 P4-t o-TB1 12-slot Screw Terminal Block for DaqBoard/2003. TB1, 12-slot P4
DBK206 P4-to-P1/P2/P3 Adapter Board with Screw-Terminals P1, P2, P 3 P4
DBK209 P4-to-P1/P2/P3 Mini-Adapter Board P1, P2, P3 P4

Note 1

P1, P2, and P3 DB37 connect ors do not exist on the DaqBoard/2000 Series, or /2000c S eri es boards,

:

but are obtained by using P4 adapters (DBK200 series). These adapters typically connect to the
DaqBoard/2000 Series [/2000c S eri es] 100-pin P4 connector via cable.

Connectivity

1

Power Supply DBKs

Power supply type DBKs are typically used in laboratory, automotive, and field applications. Input power
can come from any 10 to 20 VDC source or an AC source by using the included AC-to-DC adapter. The
DBK30A rechargeable power supply can power DBK modules where AC mains are not available (the
DBK30A outputs 28 V for powering transducers). For a large number of DBK cards, the DBK32A or
DBK33 can be installed into an expansion slot. The DBK33 is used when +5 V is required in addition to
±15 VDC. The DBK34 provides a steady 12 or 24 VDC while working with vehicle electrical systems that
may be turned on or off during testing.

Power Supply

Product Name/Description Power

DBK30A Rechargeable Battery/Excitation Module +12-14, 24-28 VDC (3.4 A-hr @ 14 VDC)
DBK32A Auxiliary Power Supply Card ±15 V @ 500 mA
DBK33 Triple-Output Power Supply Card ±15 V @ 250 mA; +5 V @ 1 A
DBK34 Vehicle UPS Module 12/24 VDC (5 A-hr @12 VDC)
DBK34A UPS Battery Module 12/24 V DC (5 A-hr @12 VDC)

1-6 Introduction to DBKs

01-17-02

DBK Option Cards and Modules

Tips on Setting up a Data Acquisition System

A successful installation involves setting up equipment and setting software parameters. In addition to this
manual, you may need to consult your Daq device or LogBook user’s manual.

DBKs should be configured before connections are made and power is applied. This sequence can prevent
equipment damage and will help ensure proper operation on startup. Many DBKs have on-board jumpers
and/or DIP switches that are used for setting channels and other variables. You will need to refer to the
individual DBK document modules to ensure that the DBKs are properly configured for you application.

Prior to designing or setting up a custom data acquisition system, you should review the following tips.
After reviewing the material you can write out the steps to setup a system that will best meet your specific
application needs.

1. The end use of the acquisition data should be used to determine how you set up and program your
acquisition system. Prior to creating the system you should understand its layout and know how you
are going to assign the channels. If you can answer the following questions you are off to a good start.
If not, you need to find the answers.

•

What engineering units, ranges, sampling rates, etc. are best for your data?

•

Will the data be charted graphically, statistically processed, or exported to other programs?

•

How will the data be used?

•

How will the data be saved?

•

What are your system’ power requirements? Using several DBKs or transducers that
require excitation current may require an extra power supply, e.g., a DBK32A.

2. Assign channel numbers.

3. Plan the location of transducers, cable runs, DBKs, the acquisition device [LogBook or Daq device],
and the computer. Label your transducers, cables, and connectors to prevent later confusion.

4. When configuring your LogBook or Daq device(s) consider the following:

•

LogBook calibration is typically performed automatically through LogView software;
however, some DBKs may require manual calibration.

•

The DaqBook and DaqBoard (ISA type) have internal jumpers and switches that you
must set manually to match your application.

•

Some DaqBook models are partially configured in software.

•

Daq PC-Cards are configured entirely in software.

•

DaqBoard/2000 Series boards are PCI type boards. They have no jumpers or switches and
are configured entirely through software.

•

cPCI DaqBoard/2000c Series boards are compact PCI (cPCI) type boards. They have no
jumpers or switches and are configured entirely through software.

•

You may need to refer to other documentation, such as Quick Starts, Installation Guides,
User’s Manuals, and pertinent DBK document modules.

5. Perform all hardware configurations before connecting signal and power. Remember to configure all
the DBK cards and modules for your application. Several jumpers and DIP switches may need to be
set (channel, gain, filters, signal mode, etc).

6. Setting up channel parameters often requires both hardware and software setup.

7. Route and connect all signal and power cables while all power is turned OFF.

8. To minimize electrical noise, route all signal lines away from any RF or high-voltage devices.

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-7

9. Follow your device’s specific installation instructions. For certain devices software should be installed
first; for others, hardware should be installed prior to software installation.

After software is loaded, remember to set the software parameters as needed for your

10.

application. The software must recognize all the hardware in the system. Measurement units
and ranges should be checked to verify that they meet your application requirements.

11. Remember to set all channels to the proper mode for your DBK or other signal source.

12. After your system is up and running, verify proper data acquisition and data storage.

13. Verify system accuracy; adjust ranges or calibrate as needed.

14. Device specific information regarding system setup and expansion can be found in the Daq and
LogBook User’s manuals; and in the applicable DBK document modules of this manual.

If you are considering system expansion, review the DBK10, DBK41, and DBK60 document

15.
modules. The best option depends on the number of DBK cards in your system. For just a few cards,
use the stackable 3-slot DBK10 low-profile expansion enclosure. For more than six cards, use the 10­slot DBK41. DBK41s can be daisy-chained to one-another to handle a large number of DBKs.

In regard to power management, you should review the DBK30A, DBK32A, and DBK33 document

16.
modules. For portable applications, the compact DBK30A rechargeable power supply can provide
power to the DBK10 or DBK41. The DBK30A also includes a 28 V output for powering 4 to 20 mA
transducers. For applications with many DBK cards (initially or in future expansion), the DBK32A or
DBK33 can be installed into any expansion slot. The DBK32A provides ±15 VDC and the DBK33
provides ±15 VDC and +5 VDC.

Signal Management

Signal Modes

Input signals come in one of two modes, single-ended or differential. Expansion modules, LogBook, and
Daq device default setting use the single-ended mode. Some DBKs use differential inputs for certain kinds
of transducers; but DBK output is always single-ended. The following text briefly describes the two signal
modes.

Note: For DaqBook/100, /112, /120, jumper settings determine the signal mode. Single-ended is the

factory-set default. For DaqBoard and Daq PC-Card, choosing between differential and single-ended
inputs is made by software command.

Single-ended mode refers to a mode, or circuit set-up, in which a voltage is measured between 1 signal line
and common ground voltage (Vcm). The measured voltage may be shared with other channels. The
advantage of a single-ended non-differential mode [over differential mode] is that it provides for a higher
channel count (16 vs 8 channels).

Differential-mode refers to a mode, or circuit set-up, in which a voltage is measured between 2 signal lines.
The resulting measured differential voltage is used for a single channel. Differential inputs reduce signal
errors and the induction of noise from ground current. The following illustration is an example of how
noise is reduced, or canceled-out, when using the differential mode.

In the schematic, voltage signal S
spikes with the same polarity, phase, and magnitude in each input signal cancel out—resulting in a clean
differential signal (S

In the schematic, signals S
if these signals were out of phase, the noise in each (indicated by
jagged lines) would still have the same magnitude, phase, and polarity.
For that reason, they would still cancel out.

is subtracted from signal S1, resulting in the output signal shown. Noise

2

- S2).

1

and S2 are shown in-phase; however, even

1

1-8 Introduction to DBKs

01-17-02

DBK Option Cards and Modules

Input Isolation

Three benefits of input isolation are circuit protection, noise reduction, and the rejection of high common
mode voltage.

•

Circuit protection. Input isolation separates the signal source from circuits that may be damaged by
the signal. (Voltages higher than about 10 V can distort data or damage chips used in data
acquisition.) High-voltage signals or signals with high-voltage spikes should therefore be isolated.
The protection can also work the other way—to safeguard a sensitive signal conditioner from a failing
device elsewhere in the system.

•

Noise reduction. Isolation eliminates ground loops for high-gain systems and multi-unit systems that
are grounded together. The chassis for each device can rest at a ground potential slightly different
from the other devices. These irrelevant currents and the spikes they may have picked up by induction
can thus be kept out of the measurement circuit.

•

Rejection of high common-mode voltage. There is a limit to the voltage applied to a differential
amplifier between ground and the amplifier inputs. Fortunately, the differential amplifier rejects high
common-mode voltage signals. High common-mode voltage and noise spikes are rejected (canceled
out) in in-phase signals (same amplitude and frequency) that are present in both the high and low
inputs at the same time.

References for Differential Modes

There are three basic types of measurement configuration related to differential mode; these are ground­referenced, shunt-referenced, and floating.

Differential Mode, Ground-Referenced

In ground-referenced configurations, the signal
voltage is referenced to a local common ground. In
most cases, the local ground will be at a different
voltage potential from the PC’s ground.

Differential inputs provide attenuation of the
common-mode noise. When in this mode, the
amplifier sees the voltage differential between the
high and low inputs (see figure). Common-mode
noise reduction occurs because noise in the high input
signal is typically the same as the noise in the low
input signal. Because of this phenomena, the voltage
difference between the 2 signals remains essentially
unaffected by noise spikes, since these spikes appear
at the same instant and at the same magnitude in both
the high and low input signals. In other words, the
noise spikes cancel each other out. As noted earlier,
even if these signals were out-of-phase, the noise
would still cancel out since the spikes in both signals
would be of the same magnitude and polarity.

Note: In the simple example (shown in the figure), the differential between the high and low signals would

result in a straight line because the signals are equal in frequency, phase, and magnitude.

Differential Mode, Shunt-Referenced

There are situations in which small voltages need to be measured and the currents flowing in the power
supply common will cause measurement errors. As shown in the figure, using the analog common as the
reference point will result in errors. These errors are the result of variations in current flow along the
common line [(I3 * Z3) + (I3 & I2) * Z2].

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-9

Differential Circuit with Shunt-reference

A way around this problem is to use a differential measurement for each shunt, with the instrument common
connected to the supply common. Each input channel will measure the shunt voltage and will reject any
voltage in the common wire (common-mode rejection).

Differential Mode, Floating (Isolated from Ground)

Floating-differential measurements are made when low-level signals must be
measured in the presence of high levels of common-mode noise (e.g., a non-

T/C

(+)

(-)

CH0H
CH0L

grounded thermocouple). When the signal source has no direct connection
to the system analog common, one must be provided. This can be done by
connecting a resistor between one of the two signal lines; usually the lower
in potential and common. A resistor of 10 to 100 kΩ is satisfactory (less
noise with the lower values).

10 k

Ω

Analog

Com.

MUX

BOAR D

DB K1 2/13/15

Floating Differential Circuit

&$87,21

Do not use differential signal hookups with the intent of achieving isolation or circuit
protection. Differential signal hookups do not provide isolation, or any other kind of
circuit protection.

Connecting Differential Amplifiers

Wire connections must be solid. Loose wires will add noise to the circuit. Low grade unshielded cables
will act as antennas, inducing more noise into the system. For this reason, all applications using a
differential amplifier require the use of quality signal cables and connectors. The signal cable used should
be constructed with:

•

Insulated outer jacket

•

Twisted signal pairs

•

Foil shield

•

Drain wire (copper stranded)

The twisted signal pairs should make use of
low impedance, stranded copper conductors;
and the foil shield should be of the type using
multiple folds.

Insulated Outer Jacket

Stranded Copper
Conductors

Fo il S h ield

Drain Wire

Twisted Signal Pair

Twisted Signal Pair

Shielded Signal Cable

The copper-stranded drain wire should be considered as part of the shield, and should be connected as
described later in this section. Proper use of a quality signal cable will result in a dramatic reduction of
noise.

The signal circuit must be connected with only one ground from the shield, as indicated in the left side of
the figure below. A mistake, which is often made, is having two grounds (one at each end of the signal
shield). Having two grounds, as shown in the right side of the figure, creates a “ground loop.” The ground
loop provides a path for current to circulate, causing the induction of noise that can affect the signal.

1-10 Introduction to DBKs

01-17-02

DBK Option Cards and Modules

CORRECT

High Input Signal

WRONG

High Input Signal

Shield

Grounding Wire

Potential difference and no path
for curre nt flow .

D iffer e n tia l
Amplifier

Low Input Signal

Shield

Grounding Wire

Ground loop caused by
current flow.

D iffer e n tia l
Amplifier

Low Input Signal

No Noise-Inducing Ground Loop Noise-Inducing Ground Loop

Aside from eliminating noise-inducing ground loops, the use of bias resistors should also be considered
with isolated signal sources. Bias resistors can be used to provide bias current for the positive and negative
(high and low) input signals to the differential amplifier. The impedance value of the bias resistors depends
on the output impedance of the signal source.

Low Input SignalHigh Inpu t Signal

R

2

D iffe r e n ti a l
A mp lifie r

S hield

Grounding Wire

R

1

Locate bias resistors (R and R ) as close
as possible to the differential amplifier.

12

A basic rule of thumb is: The value of the bias resistor should be at least 10 times the output impedance of

Ω

the signal source, but less than 1 M

.. Bias resistors should be located as close as possible to the

differential amplifier. Ground only one end of the signal shield.

Unipolar and Bipolar Measurement

Unipolar signals are always zero or positive. Bipolar signals can be negative or positive and typically range
from -5 to +5 V (-10 to +10 V for the DaqBoard/2000). Using one or the other depends on the signal from
the transducer and its signal conditioning. If the DBK (or other signal conditioner) outputs a bipolar signal,
then the LogBook or Daq device should be set to bipolar. If the LogBook or Daq device sequencer is using
the wrong mode for a channel, that channel’s reading may be clipped or in error. Reading a bipolar signal
in unipolar mode misses half the signal, and the half received is not converted with optimal resolution.

Note: The different DBKs can use either or both signal modes. Refer to the DBK documentation, and

verify that the DBK and the LogBook or Daq device are set to the proper mode for each channel.

12-Bit vs 16-Bit Resolution

An analog-to-digital converter (ADC) converts an analog voltage to a digital number. The digital number
represents the input voltage in discrete steps with finite resolution. The number of bits that represent the
digital number determines ADC resolution. An n-bit ADC has a resolution of 1 part in 2

•

12-bit resolution is 1 part in 4096 (in binary powers, 2
range.

•

16-bit resolution is 1 part in 65,536 (in binary powers, 2

12

) and corresponds to 2.44 mV for a 10 V

16

) and corresponds to 0.153 mV in a 10 V

n

.

range.

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-11

System Noise

Averaging

Electrical noise can present problems even with good equipment; thus, controlling noise is imperative.
Some techniques avoid or prevent noise sources from entering the system; other techniques remove noise
from the signal.

Laboratory and industrial environments often have multiple sources of electrical noise. An AC power line
is a source of 50/60 Hz noise. Heavy equipment (air conditioners, elevators, pumps, etc.) can be a source of
noise, particularly when turned on and off. Local radio stations are a source of high-frequency noise, and
computers and other electronic equipment can create noise in a multitude of frequency ranges. Thus, an
absolute noise-free environment for data acquisition is not realistic. Fortunately, noise-reduction techniques
such as averaging, filtering, differential voltage measurement, and shielding are available to reduce noise to
an acceptable level.

Note: Additional noise-reduction information is contained in the section, “Signal Modes,” especially in the

paragraphs pertaining to connections, signal cables, and ground loops.

Averaging is done in software after several samples have been collected. Depending on the nature of the
noise, averaging can reduce noise by the square root of the number of averaged samples. Although
averaging can be effective, it suffers from several drawbacks. Noise in measurements only decreases as the
square root of the number of measurements—reducing RMS noise significantly may require many samples.
Thus, averaging is suited to low-speed applications that can provide many samples.

Note: Only random noise is reduced or eliminated by averaging. Averaging will not reduce or eliminate

any signal that is periodic.

Analog Filtering

A filter is an analog circuit element that attenuates an incoming signal according to its frequency. A low­pass filter attenuates frequencies above the cutoff frequency. Conversely, a high-pass filter attenuates
frequencies below the cutoff. As frequency increases beyond the cutoff point, the attenuation of a single­pole, low-pass filter increases slowly. Multi-pole filters provide greater attenuation beyond the cutoff
frequency but may introduce phase (time delay) problems that could affect some applications.

Filter circuits can be active or passive:

•

Active. The DBK18 Low-Pass Filter Card has an instrumentation amplifier with variable gain and
filter configurations. The DBK18 uses an active 3-pole filter (mostly contained within the UAFF42
ICs) that can be configured as a Butterworth, Bessel, or Chebyshev filter with corner frequencies up
to 50 kHz. Filter properties depend on the values of resistors and capacitors. These components
can be changed by the user.

•

Passive. The DBK11 has a prototype area on the PC board for attaching non-powered components
such as resistors and capacitors. The user chooses component values to produce the desired
properties.

Input and Source Impedance

As shown in the following figure, The input impedance (Ri) combines with the transducer’s source
impedance (R

) forming a voltage divider. This divider distorts the voltage being read at the analog-to-

s

digital converter. The actual voltage read is represented by the equation:

V

= VT × [Ri / (Ri + Rs)] [ Vt - IbRs)

read

The low source impedance (R
presents no problem. Some transducers, such as
piezoelectric types, have high source impedance. These
transducer types should be used with a charge-sensitive
amplifier of low output impedance.

1-12 Introduction to DBKs

) of most signals usually

s

01-17-02

DBK Option Cards and Modules

Crosstalk

Crosstalk is a type of noise related to source impedance and capacitance, in which signals from one channel
leak into an adjacent channel, resulting in interference or signal distortion. The impact of source impedance
and stray capacitance can be estimated by using the following equation.

T = RC

Where T is the time constant, R is the source impedance, and C is the stray capacitance.

High source (transducer) impedance can be a problem in multiplexed A/D systems like the DBK12,
DBK13, DBK15. When using more than 1 channel, the channel input signals are multiplexed into the
circuit card. The multiplexer samples each signal for only 10 µs and then switches to the next input signal.
A high-impedance input interacts with the multiplexer’s stray capacitance and causes crosstalk and
inaccuracies in the A/D sample. In such cases, the source impedance should be less than 1 kΩ. If the
source impedance exceeds this value, sampling problems can be expected.

A solution to high source impedance in relation to multiplexers involves the use of buffers. The term buffer
has several meanings; but in this case, buffer refers to an operational amplifier having high input impedance
but very low output impedance. In the example illustrated, a buffer has reduced the source impedance from
10 kΩ to effectively 0 kΩ. Placing such a buffer on each channel (between the transducer and the
multiplexer) prevents the multiplexer’s stray capacitance from combining with the high input impedance
(10 kΩ in the example). This use of a buffer also stops transient signals from propagating backwards from
the multiplexer to the transducer.

Using DBK Cards and Modules for Signal Condi tioning

The DBK signal-conditioning units are designed for use with Daq devices and LogBooks. Although the
DBK options can be used with ISA or PCI bus-based data acquisition boards from other vendors; they
perform best when used with an acquisition device that can dynamically select channel, gain, and range.
Dynamic channel and gain/range make it possible to have high channel-to-channel scan rates with a variety
of transducers.

DBK output signals can be bipolar, e.g., -5 to +5 V, or unipolar, e.g., 0 to 10 V. The user can select a range
of relevant values to correspond to the lowest signal (e.g., -5 or 0 V) and the highest signal (e.g., 5 or 10 V)
signal. This type of range selection guarantees the highest resolution in 12-bit or 16-bit conversion.

DBK modules share the same footprint as the DaqBooks and LogBooks. This dimensional aspect provides
for convenient stacking of modules with each other and with most notebook PCs. Note that most DBK
modules have their own power supply.

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-13

Channel Control and Expansion

g

g

In a Daq device or LogBook system, DBK expansion cards and modules can increase the number of analog
input channels from 16 base channels to 256 input channels (16 × 16). The configuration will vary
depending on the DBK’s channel capacity; for example, four 4-channel DBKs or two 8-channel DBKs can
share the same base channel. As part of the multiplexing scheme, each DBK card provides a single output
that must be directed to one of the 16 base channels via the DBK’s JP1 jumper setting.

DBK card or module

P1

P1

Daq de vice System
or Lo

Book System

16

expansion

channels

MUX

4

PGA

JP1

channel

2

select

jumper

2 bits select 1 of 4

4 bits s elect 1 of 16 inp uts

ains

16

base

channels

4 bits select

1 of 16

inputs

MUX

4

Sequen cer

PGA

2

2 bits select
1 of 4 gains

ADC

100 kHz

Clock

Channel Control and Expansion Block Diagram

The above figure shows the functional parts related to channel control and expansion. An explanation of
the diagram follows.

•

The sequencer selects the channel and gain by controlling multiplexers (MUX) and

programmable gain amplifiers (PGA) in either the LogBook or the Daq device and the DBK.
The sequencer uses 4 expansion address lines to provide 16 unique channel addresses for each
base channel. A 100 kHz clock and user programming of the scan sequence control the
sequencer.

Note: DaqBoard/2000 Series [and cPCI Daqboard/2000c] Boards allow for selection of 100 kHz,

or 200 kHz internal clock speed via software.

•

The DBK multiplexer selects 1 of 16 (max) channels as directed by the sequencer. The selected

signal travels to the PGA, to the channel-selection jumper, then to the Daq device, or LogBook
via P1.

1-14 Introduction to DBKs

•

The Daq device or LogBook multiplexer selects 1 of 16 base channels from P1 input lines as
directed by the sequencer. The selected signal goes to the PGA and then to the A/D converter
(A/D).

•

The PGAs can vary the gain on a per channel basis as directed by the sequencer. For DBKs with
a PGA, the sequencer can combine the gains of the DBK PGA and the LogBook or Daq device
PGA for a variety of gain settings.

•

The P1 interface has a signal line for each of the 16 base channels and control lines for gain
setting (pins 5, 6) and sub-channel selection (pins 3, 4, 22, 23).

•

The JP1 channel select jumper in the DBK can be placed on pins for channel 0 through channel

15. Until the base channel capacity is filled (16 max), multiple cards can use the same JP1
channel setting if their DIP switches are set to identify unique sub-channel card numbers.

Note: The channel select header on DBK17 and DBK18 is labeled J1 instead of JP1.

01-17-02

DBK Option Cards and Modules

The following table details how expansion channels are numbered in DaqView and LogView. API
Channels are used in Daq devices by third party programs. Note that API Channels are not used in

LogBook systems.

Channel Numbering

DaqView or LogView

Channel

0 to 15 Local channels 0 to15
0-0 to 0-15 0 to 15 of A/D exp. card 0 16 to 31
1-0 to 1-15 0 to 15 of A/D exp. card 1 32 to 47
2-0 to 2-15 0 to 15 of A/D exp. card 2 48 to 63
3-0 to 3-15 0 to 15 of A/D exp. card 3 64 to 79
4-0 to 4-15 0 to 15 of A/D exp. card 4 80 to 95
5-0 to 5-15 0 to 15 of A/D exp. card 5 96 to 111
6-0 to 6-15 0 to 15 of A/D exp. card 6 112 to 127
7-0 to 7-15 0 to 15 of A/D exp. card 7 128 to 143
8-0 to 8-15 0 to 15 of A/D exp. card 8 144 to 159
9-0 to 9-15 0 to 15 of A/D exp. card 9 160 to 175
10-0 to 10-15 0 to 15 of A/D exp. card 10 176 to 191
11-0 to 11-15 0 to 15 of A/D exp. card 11 192 to 207
12-0 to 12-15 0 to 15 of A/D exp. card 12 208 to 223
13-0 to 13-15 0 to 15 of A/D exp. card 13 224 to 239
14-0 to 14-15 0 to 15 of A/D exp. card 14 240 to 255
15-0 to 15-15 0 to 15 of A/D exp. card 15 256 to 271

1

Note: DaqView identifies channel s for some DBKs (e.g., DB K4) with a 3-part

number for local channel, card, and sub-address.

2

Note: In differential mode, only channels 0 to 7 are valid.

1

High-speed digital I/O

Signal Source

(DaqBook/100/200 and
DaqBoard/100A/200A)

2

API

Channel

0 to 15

272

In addition to the base channel selection on JP1, many DBKs must be set to the sub-channel (or card)
number by a DIP-switch labeled SW1 or S1. Since DBKs vary in their channel capacity and identification,
refer to the respective DBK document modules.

Example. Refer to the above table (the 1-0 to 1-15 row) and to the following figure. To select channel 15

DBK Option Cards and Module

on a DBK card that is connected to base channel 1:

a) set the sequencer expansion address to 1111
b) set the base address to 0001
c) set JP1 to channel 1
d) Depending on the DBK, set the DIP-switch to identify one of

the multiple cards on a single channel.

The corresponding API channel number would be 47; i.e., DaqView Channel 1-15 (see table).

Note that API Channels are not used in LogBook systems.

01-17-02

Introduction to DBKs 1-15

g

DBK card or mo dule

CH1

P1

P1

CH1

Daq device System

or Lo

Book System

MUX

CH15

Signal Acquisition

Sequencer

The hardware sequencer performs several functions:

•

Allows each channel to have an independent gain.

•

Ensures that channels are scanned at exactly 10 µs intervals.

•

Allows channels to be accessed randomly in the scan rather than “start channel to end channel”.

•

Provides high-speed access to expansion modules.

Gain adjusted analog
input from P1

4
1111

PGA

2

JP1 channel

sele c t ju m pe r

Example Channel Selection

External
Multiple xer
Control

MUX

Base Ad dress set to 0001

Expansion Address set to 1111

8 DE/16 SE
Analog Input
Multiple xer

4
0001

Sequencer

Programmable
G a i n A mpl ifier
×1, ×2, ×4, × 8

PGA

2

ADC

100 kHz

Clock

16 High-Speed
Digital Inputs

4 signals to be used as:

Analog
trigge r-in
com parator

Com p uter output signal
through digital-to-analog
converters

1

G a in A dju st

2

Polarity setting: bipolar or unipolar

An alog input
fro m P 1

Trigger
input

Trigger
select

100 kHz
clock

512-S tep Random Access
Channel/Gain Sequencer

Ch

0
1
2

...

15

Signal from
PC (ISA)
Bus interface

Main

×1
×2
×8

...

×4

Expanded

2

Set. Set.

ChGa Ga

uni

16

uni

17

bi

...

...

271

bi

272

Programmable
sequencer timebase,
10 s to 10 hours

µ

21

1

bi

×60

bi

×20

...

...

uni

×40

n/a

n/a

Seque ncer R eset

general purpose inputs
o r

1 Aux. C ounter Gate
1 TTL Trigger Input
2 Gain Se le c t Ou tput s
( )

for expansion boards

An alog input
fro m P 1

The LogBook or Daq device holds the scan information in its internal sequencer. On every timebase “tick”,
the sequencer steps through all the programmed channels and sets the gain for each channel (also the
unipolar/bipolar setting for the Daq device 200 series and DaqBoard/2000 Series [/2000c Series board]).
Thus, each sample in a scan is read optimally. In addition to controlling the LogBook or the Daq device,
the sequencer controls the programmable features on expansion cards via the P1 connector.

This architecture ensures that the same 10 µ s sampling (5 µs or 10 µ s for DaqBoard/2000 Series, and
cPCI DaqBoard/2000c Series boards) exists for external channels as well as internal channels.

1-16 Introduction to DBKs

01-17-02

DBK Option Cards and Modules

Scan Group

g

g

y

gg

µ

µ

y

g

g

Scan Period

(Im mediate t o
10 hours)

 V

All channels w ithin scan
measured at 10 µs/channel.

µ

rou p a re

Time

Scan Rate

Triggering

Time

#16

Channel
Gain

#2

x1

#4

x8

#7

x8

#2

x2

ital

Di
Input

#18
x100

#19

x10

x1000

Most sampling of analog signals occurs on the timebase of the LogBook or the Daq device clock. The scan
period is the time duration between successive scans. Inversely, the scan rate, or scan frequency is the

number of scans per time interval, usually expressed in scans per second. The channels within the scan are
always sampled at a fixed period of 10 µs (100 kHz rate), or 5 µs (200 kHz rate); or 10 µs for the
DaqBoard/2000 Series[/2000c Series]. Generally, the sampling frequency must be greater than twice the
highest signal frequency of interest to prevent aliasing error.

Note 1: With DaqBoard/2000 Series and /2000c Series boards, either 100 kHz or 200 kHz can be selected

to be used as the internal clock speed. To ensure signal accuracy the 100 kHz speed must be
selected when using a DBK12, DBK13, DBK15, DBK19, DBK53 or DBK54 in conjunction with
DaqBoard/2000 Series, or cPCI DaqBoard2000c Series boards.

Note 2: Except in the case of a single-channel scan, the sampling rate per channel can be much slower than

the scan rate.

Triggering controls an acquisition cycle. Once the system is armed, a trigger is required to collect the data.
Typically, three data collection parameters are specified: the pre-trigger count, the post-trigger scan count,
and the trigger source. The user must determine the triggering requirement based on the nature of the
measurement and the amount of data needed to satisfy the system’s purpose.

pe of Trigger Source

T

Im med ia te

Hit

Ke
External TTL
Cha nnel Valu e - Ris in

- F allin

Pre-Trigger Scan Coun t

 V

 V

The pre-trigger scan count specifies the number of scans that are to be collected before the trigger

•

Scan Period

(10 µs to 10 hours)

Trigger Even t

Post -Tri

er Scan Count

Time

point. If the pre-trigger scan count is greater than zero, the system will continuously collect data until
the trigger is satisfied. If no pre-trigger scans are required, the system sits idle until the trigger; then,
it collects the post-trigger scans before it disarms.

DBK Option Cards and Module

01-17-02

Introduction to DBKs 1-17

•

The post-trigger scan count specifies the number of scans to be collected after the trigger point.
After the trigger, the post-trigger scans will be collected as programmed and then the system will
disarm itself.

•

The trigger source can be a software command, an external TTL input, etc. An analog input channel
on reaching a specified voltage level can be used to trigger the system. (In this mode, an analog
output channel is used to internally set the analog threshold—making it unavailable for other use.)

Counter/Timer Functions

Counter/timer circuits are used for counting digital events, timing digital pulses, and generating square
waves and pulses. Counter/timer functions are available from the P3 interface.

The table shows the P3 pinout for the 4 counter and 2 timer channels.

•

IN - a digital input that increments the counter and provides a timebase for counter operation.

•

OUT - an output of digital square waves and pulses.

Counter/Timer Pins on P3

Pin Signal Name

15 TMR 0 OUT Timer 0 output
16 TMR 1 OUT Timer 1 output
17 CTR 2 IN
18 CTR 0 IN
35 CTR 3 IN
36 CTR 1 IN

Description

Counter 2 input
Counter 0 input
Counter 3 input
Counter 1 input

The counter channels can act as 4 independent 16-bit up-counters.

The timer channels are driven by an internal timebase of 1 MHz which can be divided by
1 to 65535 to obtain output frequencies from 15 Hz to 1 MHz.

Simultaneous Sample and Hold (SSH)

Some applications require every channel in a scan group to be read at the same instant, as opposed to being
read with 10 µs between channels. Acquiring multiple readings at the same instant is accomplished with
Simultaneous Sample and Hold (SSH).

An example of an SSH application is as follows. In the example, a performance analysis of an engine needs
to indicate cylinder pressure and temperature, piston strain and position, valve position, and engine rpm and
vibration—all at the same instant. Simultaneous Sample and Hold (SSH) is a means of obtaining such
instantaneous data on multiple channels while avoiding time-skew problems.

1-18 Introduction to DBKs

01-17-02

DBK Option Cards and Modules

The previous figure can be used to understand how SSH is used in the DBK17 SSH Card. The process is as

M

S

O

(C)

follows:

•

Input signals pass through an instrumentation amplifier and into a sample-and-hold stage.

•

When the sample enable line goes high, each channel’s sample-and-hold stage will “freeze”
the current analog value. The values for all channels are separately “latched” within 50 ns of
each other.

•

The signals are held in a stable condition, while the multiplexer switches through all channels.

•

The multiplexer sends the signals [one-by-one] to be digitized by the analog-digital converter
(ADC) in the primary data acquisition device.

•

The resulting data is a snapshot of conditions at an instant, but the multiplexing and analog-to­digital conversion are spread over a longer time interval.

•

The simultaneous sample and hold circuit allows you to gather up to 256 simultaneous
samples using sixty-four DBK17s.

Two-Point Calibration of a Temperature Measurement System

Note: In the following text a temperature measurement system consisting of a DaqBook, a DBK19

thermocouple card, and DaqView is referred to. However, it is important to note that the two-point
calibration method can be applied to measurement systems that consist of other acquisition devices
and software.

Overview

Two-point calibration makes use of correction constants
to eliminate offset and gain errors in a temperature
measurement system.

The graph shows an example for a temperature
measuring system, with temperature expressed in degrees
Celsius.

The sensor output is on the horizontal axis and system
response is on the vertical.

The graph illustrates the following bulleted points:

•

The system has a linear response. Most thermocouple measurement devices have a software
driver, which corrects for the nonlinear output voltage of each thermocouple type. Normally, there
is no provision for linearity adjustment by the user.

•

The system has an offset at 0°C, which can be eliminated by introducing an offset correction. This
is the first point of a two-point correction.

100

90

°

80
70

utput

60

ystem

50
40
30

easurement

20
10

0

10 20 30 40 50 60 70 80 90 100

Tem perature Sensor O utput ( C)°

•

The system has a gain error at 100°C, which can be eliminated by introducing a gain (slope)
correction. This is the second point of a two-point correction.

Suppose you have a temperature measurement system consisting of a DaqBook, a DBK19 thermocouple
card, and DaqView data acquisition software. The DBK19 was shipped with a diskette of calibration
constants. These calibration constants are specific to the DBK19.

DBK Option Cards and Module

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Introduction to DBKs 1-19

Download instructions for loading the constants into DaqView were included with the DBK19. The
constants will improve the accuracy of each DBK19 channel when amplifying the thermocouple's millivolt
output, which is read by the DaqBook.

The temperature measurement system, as well as the thermocouple itself, can still have the following types
of errors:

•

Thermocouple error (departure from performance of an ideal T/C of that type)

•

CJC sensor error (±1°C maximum for the DBK19)

•

The DaqBook may have small calibration errors

In some applications, it is possible to ignore these sources of errors and still obtain useful results from the
temperature measurement system. However, the only way to optimize the performance of the system is to
perform an end-to-end calibration. This is done by applying two different temperatures to the thermocouple
connection: one temperature is close to 0°C and the other is at approximately full scale.

Then observe the two corresponding temperature readings in DaqView, and use this information to derive
the values of “m” and “b” in the line slope equation “mx + b.” In this equation, the value of “m” is usually
called the scale, and the value of “b” is usually called the offset. When both the offset and gain correction
values are applied, the system errors are reduced to their lowest level.

An Example of Two-Point Calibration

For illustration, suppose the temperature measurement system consists of a DaqBook/100, DBK19
thermocouple card, and DaqView software. (The following calibration procedure also applies to
temperature measurement systems made up of similar products, but the discussion is simplified with a
specific example.) After setting up the DBK19 card in DaqView as described previously, consider one of
the channels on the DBK19, for example, channel 2. Suppose a type T thermocouple connected to this
channel. In DaqView, select a sampling frequency of 1 Hz and an averaging factor of 200 so that the
readings you get are steady and not fluctuating rapidly.

When you look at this channel in DaqView, the default units are in degrees Celsius. With the acquisition
“off”, click on the cell in DaqView in the Units column for channel 2. You will see an engineering units
pull-down menu in a dialog box above the spreadsheet area. Click on the down arrow in this dialog box, and
then select the “mx + b” option. You will note that the default values of scale and offset are m=1 and b=0
for engineering units of degrees C. These values need to be changed to ones that will give more accurate
temperature readings.

To do this, first place the thermocouple for channel 2 in an environment with a known temperature, for
example an ice bath. Click on the Start All Indicators button in DaqView, and observe the Readings column
for channel 2. Wait until the reading stabilizes, then write down the number in degrees C. Call this reading
the “first actual reading” or RA1, and suppose it is:

RA1 = 2.1°C

Since this reading was supposed to be 0°C, call the first correct reading RC1:

RC1 = 0°C

Place the thermocouple for channel 2 in a second known environment. This might be a thermocouple block
calibrator or a fluidized sand bath. In this example, assume that the calibrator has been set to100°C.
Observe the reading in DaqView for channel 2, wait until it stabilizes, then write down this number in
degrees Celsius. Call this reading the “second actual reading” or RA2, and suppose it is:

RA2 = 104°C

Since the correct second reading was supposed to be 100°C, write down the correct value as:

RC2 = 100°C

Stop the monitoring process in DaqView by clicking on the Stop All Indicators button.

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DBK Option Cards and Modules

Calculation of Scale and Offset

Using the above information, calculate the values of scale (m) and offset (b) that will compensate for the
measurement errors (RA1 and RA2). This is possible because the correct and actual readings are related by
the (mx + b) equations:

RC1 = m(RA1) + b
and
RC2 = m(RA2) + b

Substituting in the values noted in the above calibration process:

RC1 = m(RA1) + b
0 = m(2.1) + b

RC2 = m(RA2) + b
100 = m(104) + b

Solving for “m” results in:

100 = m(104 -2.1)
m = 100/(104-2.1) = 0.9814.

Substituting this value of “m” to solve for the value of “b”:

0 = 0.9814 (2.1) + b
b = -2.0608.

Implementing the Scale and Offset Constants in DaqView

To implement the scale and offset constants in DaqView, first make sure that the acquisition process is
turned off. Then, click on the cell in the Units column for channel 2. The engineering units pull-down menu
above the grid becomes active; click on the down arrow and select the “mx + b” option.

After doing that, you have the ability to enter new numbers for m and b. Perform those entries and click on
OK to save them. You can then place the thermocouple back in the ice and fluidized sand baths, observe the
new readings, and note the improvement in their accuracy.

If you want optimum accuracy of all channels in the temperature measurement system, you should perform
the two-point calibration process for each channel.

Converting Degrees from Celsius to Fahrenheit

Once you have performed the two-point calibration process and determined the scale and offset values for
units of degrees Celsius, you can use this information to find the corresponding scale and offset values for
other temperature units. In the previous example, the calibration process produced the following equation
for “mx + b”, using units of degrees Celsius:

RC (°C) = 0.9814 * RA (°C) - 2.0608

To convert to degrees Fahrenheit, use the relationship:

RC (°F) = 1.8 * RC (°C) + 32

Substituting the latter equation into the former yields:

So the new values of m and b are:

These are the scale and offset values that you should enter. Note that RA is still in degrees Celsius since the
raw reading produced by the data acquisition software is in degrees Celsius.

DBK Option Cards and Module

RC (°F) = 1.8 * [0.9814 * RA (°C) - 2.0608] + 32
RC (°F) = 1.7665 * RA (°C) + 28.29

m' = 1.7665
b' = 28.29

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Introduction to DBKs 1-21

One Known Temperature Environment

Suppose that you only have one known temperature environment, such as an ice bath. In this case only one
parameter in the “mx + b” equation can be determined for system calibration. This is called single-point
calibration. Since this is normally the largest source of error, single-point calibration is used to correct the
offset.

Using the same information as in the first example, and supposing that the only actual reading available is
called RA:

RA = 2.1°C

Since this reading was supposed to be 0°C, call the correct reading RC:

RC = 0°C

Substituting these values into the mx + b equation results in:

RC = 0 = m (2.1) + b

In a single-point calibration, it is assumed that the value of the scale parameter is completely accurate; that
is, m = 1. Using this information in the above equation results in:

0 = 1(2.1) + b,
b = -2.1

These are the scale (m = 1) and offset (b = -2.1) values that should be entered into DaqView.

Use of a Temperature Calibrator

Occasionally, it is impractical or difficult to get physical temperature references for system calibration. The
temperature region of interest may be far removed from the example temperatures of 0°C and 100°C.
Accurate temperature baths may not be available.

In these cases, you should use a temperature simulation instrument that lets you dial in your thermocouple
type. The simulator should also let you set the two calibration temperatures that are correct for your
application. The calibrator then generates milli-volt signals into the DBK19 card (or other temperature
measurement product). These signals correspond to those that would be generated, by the chosen
thermocouple types, at the selected temperatures. A disadvantage of this approach is that thermocouple
errors are not corrected or compensated.

For many applications, where the thermocouple is used at lower temperatures, a single-point calibration is
sufficient. In general, thermocouples have little error at 0°C. The thermocouple error tends to increase
linearly as the temperature increases.

CE Compliance

The European Union (EU) first developed CE standards in 1985. The standards include specifications for
safety and for EMI emissions and immunity. Now, all relevant products sold in Europe must meet these
standards.

Although CE compliance is not required in the United States, the standards are often adopted by U.S.
companies since they improve product safety, reduce noise, and minimize ESD problems.

In contracted and in-house testing, most LogBook and Daq device products met the required specifications.
Others were redesigned to meet compliance. In some cases, alternate product versions, shield plates, edge
guards, special connectors, and add-on kits were developed. The section, CE Enhancements for Existing

Products, located at the end of this chapter, includes examples.

CE-compliant products bear the “CE” mark and include a Declaration of Conformity stating the
particular specifications and conditions that apply. Test Records and supporting documentation
that validate compliance are kept on file at the factory.

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DBK Option Cards and Modules

CE Standards and Directives

The electromagnetic compatibility (EMC) directives specify two basic requirements:

•

The device must not interfere with radio or telecommunications.

•

The device must be immune from electromagnetic interference from RF transmitters etc.

The standards are published in the Official Journal of European Union under direction of CENELEC
(European Committee for Electrotechnical Standardization). The specific standards relevant to LogBook or
Daq device equipment are listed on the product’s Declaration of Conformity and include: CISPR22:1985;
EN55022:1988 (Information Technology Equipment, Class A for commercial/industrial use); and
EN50082-1:1992 for various categories of EMI immunity.

The safety standard that applies to LogBook and Daq device products is EN 61010-1 : 1993 (Safety

Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use, Part 1: General
Requirements). Environmental conditions include the following:

•

indoor use

•

altitude up to 2000 m

•

temperature 5°C to 40°C (41°F to 104°F)

•

maximum relative humidity 80% for temperatures up to 31°C (87.8°F) decreasing linearly
to 50% relative humidity at 40°C (104°F)

•

mains supply voltage fluctuations not to exceed ±10% of the nominal voltage

•

other supply voltage fluctuations as stated by the manufacturer

•

transient overvoltage according to installation categories (overvoltage categories) I, II and III.
For mains supply, the minimum and normal category is II.

•

pollution degree Ior II in accordance with IEC 664.

For clarification, terms used in some Declarations of Conformity include:

Safety Conditions

Users must comply with all relevant safety conditions listed in the Declarations of Conformity and in the
user documentation. This manual, LogBook, and Daq device hardware use the following Warning and
Caution symbols:
(If you see these symbols on a product, carefully read the related information and be alert to the possibility
of personal injury).

•

pollution degree: any addition of foreign matter, solid, liquid or gaseous (ionized gases) that
may produce a reduction of dielectric strength or surface resistivity. A pollution degree I has
no influence on safety and implies: the equipment is at operating temperature with non­condensing humidity conditions; no conductive particles are permitted in the atmosphere;
warm-up time is sufficient to avert any condensation or frost; no hazardous voltages are applied
until completion of the warm-up period. Pollution degree II implies the expectation of
occasional condensation.

•

overvoltage (installation) category: classification with limits for transient over-voltage,
dependent on the nominal line voltage to earth. Category I implies signals without high
transient values. Category II applies to typical mains power lines with some transients.

This warning symbol is used in this manual or on the equipment to warn of possible
injury or death from electrical shock under noted conditions.

This warning/caution symbol is used to warn of possible personal injury or equipment
damage under noted conditions.

LogBook and Daq device products contain no user-serviceable parts; refer all service to qualified
personnel.

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Introduction to DBKs 1-23

The specific safety conditions for CE compliance vary by product; but general safety conditions
include:

•

The operator must observe all safety cautions and operating conditions specified in the
documentation for all hardware used.

•

The host computer and all connected equipment must be CE compliant.

•

All power must be off to the device and externally connected equipment before internal access to
the device is permitted.

•

Isolation voltage ratings: do not exceed documented voltage limits for power and signal inputs.
All wire insulation and terminal blocks in the system must be rated for the isolation voltage in use.
Voltages above 30 Vrms or ±60 VDC must not be applied if any condensation has formed on the
device.

•

Current and power use must not exceed specifications. Do not defeat fuses or other over-current
protection.

Emissions/Immunity Conditions

The specific immunity conditions for CE compliance vary by product; but general immunity conditions
include:

•

Cables must be shielded, braid-type with metal-shelled connectors. Input terminal connections are
to be made with shielded wire. The shield should be connected to the chassis ground with the
hardware provided.

•

The host computer must be properly grounded.

•

In low-level analog applications, some inaccuracy is to be expected when I/O leads are exposed to
RF fields or transients over 3 or 10 V/m as noted on the Declaration of Conformity.

CE Enhancements for Existing Products

This section of describes three CE enhancements.

•

DBK41/CE

•

Edge Guards for the DBK5, DBK8, and DBK44

•

BNC Connectors for CE compliance

Edge Guards for DBK5, DBK8, and DBK44

A plastic barrier attached to the end of a DBK card helps prevent access to leads, and to live circuits.
The edge guards attach to DBKs (see figure below) that are mounted in a DBK41/CE, with EMI shield
plates. The access slot allows insulated wires to pass through the barrier.

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DBK Option Cards and Modules