Title Page

UM-24789-H

DT9838User’s ManualCopyright Page

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© 2019 Measurement Computing Corporation. All rights reserved. No part of this publication
may be reproduced, stored in a retrieval system, or transmitted, in any form by any means,electronic, mechanical, by photocopying, recording, or otherwise without the prior written
permission of Measurement Computing Corporation.

NoticeMeasurement Computing Corporation does not authorize any Measurement Computing
Corporation product for use in life support systems and/or devices without prior written consent
from Measurement Computing Corporation. Life support devices/systems are devices or systems
that, a) are intended for surgical implantation into the body, or b) support or sustain life and whose
failure to perform can be reasonably expected to result in injury. Measurement Computing
Corporation products are not designed with the components required, and are not subject to thetesting required to ensure a level of reliability suitable for the treatment and diagnosis of people.

FCC
Page

Radio and Television InterferenceThis equipment has been tested and found to comply with CISPR EN55022 Class A andEN61000-6-1 requirements and also with the limits for a Class A digital device, pursuant toPart 15 of the FCC Rules. These limits are designed to provide reasonable protection against
harmful interference when the equipment is operated in a commercial environment. Thisequipment generates, uses, and can radiate radio frequency energy and, if not installed andused in accordance with the instruction manual, may cause harmful interference to radio
communications. Operation of this equipment in a residential area is likely to cause harmfulinterference, in which case the user will be required to correct the interference at his own
expense.
Changes or modifications to this equipment not expressly approved by Data Translation
could void your authority to operate the equipment under Part 15 of the FCC Rules.

Note: This product was verified to meet FCC requirements under test conditions that
included use of shielded cables and connectors between system components. It is importantthat you use shielded cables and connectors to reduce the possibility of causing interference
to radio, television, and other electronic devices.

Canadian Department of Communications Statement
This digital apparatus does not exceed the Class A limits for radio noise emissions fromdigital apparatus set out in the Radio Interference Regulations of the Canadian Department ofCommunications.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la class A prescrites dans le Règlement sur lebrouillage radioélectrique édicté par le Ministère des Communications du Canada.

Table of Contents

Table of Contents
About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intended Audience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
How this Manual is Organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conventions Used in this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Related Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Where To Get Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 1: Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
DT9838 Hardware Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Supported Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Getting Started Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Chapter 2: Setting Up and Installing the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
(Optional) Applying Power to the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Attaching Modules to the Computer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Connecting Directly to the USB Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Connecting to an Expansion Hub . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Configuring the DT9838 Device Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Chapter 3: Wiring Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Preparing to Wire Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
General Wiring Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Analog Input Connector Pin Assignments (RJ50 Connector) . . . . . . . . . . . . . . . . . . . . 39
Connecting a General-Purpose or Bridge-Completion Accessory . . . . . . . . . . . . . . . . . . . . 40
Connecting Quarter-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Wiring a Quarter-Bridge (Axial and Bending) Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Remote Sensing In Quarter-Bridge Configurations . . . . . . . . . . . . . . . . . . . . . . . . . 45
Shunt Calibration in Quarter-Bridge Configurations . . . . . . . . . . . . . . . . . . . . . . . 46
Wiring a Quarter-Bridge Temp Comp Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Remote Sensing In Quarter-Bridge Temp Comp Configurations . . . . . . . . . . . . . 48
Shunt Calibration in Quarter-Bridge Temp Comp Configurations . . . . . . . . . . . . 49
Connecting Half-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Wiring a Half-Bridge Poisson Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Remote Sensing In Half-Bridge Poisson Configurations . . . . . . . . . . . . . . . . . . . . 52
Shunt Calibration in Half-Bridge Poisson Configurations . . . . . . . . . . . . . . . . . . . 53

5

Contents
Wiring a Half-Bridge Bending Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Remote Sensing In Half-Bridge Bending Configurations . . . . . . . . . . . . . . . . . . . . 55
Shunt Calibration in Half-Bridge Bending Configurations . . . . . . . . . . . . . . . . . . 56
Connecting Full-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Wiring a Full-Bridge Bending Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Remote Sensing in Full-Bridge Bending Configurations . . . . . . . . . . . . . . . . . . . . 59
Shunt Calibration in Full-Bridge Bending Configurations . . . . . . . . . . . . . . . . . . . 59
Wiring a Full-Bridge Bending Poisson Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Remote Sensing in Full-Bridge Bending Poisson Configurations . . . . . . . . . . . . . 61
Shunt Calibration in Full-Bridge Bending Poisson Configurations . . . . . . . . . . . 62
Wiring a Full-Bridge Axial Poisson Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Remote Sensing in Full-Bridge Axial Poisson Configurations . . . . . . . . . . . . . . . . 64
Shunt Calibration in Full-Bridge Axial Poisson Configurations . . . . . . . . . . . . . . 65
Connecting Load Cells and Other Transducers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Connecting Voltage Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Connecting a Tachometer Input Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Connecting an External Trigger Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Chapter 4: Verifying the Operation of a Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Select the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Measure Strain Gage Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Configure the Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Configure the Recording Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Configure the Acquisition Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Start the Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Chapter 5: Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Analog Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Specifying a Single Analog Input Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Specifying One or More Analog Input Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Bridge Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Quarter-Bridge Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Quarter-Bridge Temp Comp Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Half-Bridge Poisson Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Half-Bridge Bending Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Full-Bridge Bending Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Full-Bridge Bending Poisson Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Full-Bridge Axial Poisson Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Transducer Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Bridge Excitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Remote Sensing and Lead Wire Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

6

Contents
Shunt Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Shunt Calibration Equation for the Quarter-Bridge and Quarter-Bridge
Temp Comp Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Shunt Calibration Equation for the Half-Bridge Poisson Configuration . . . . . . 102
Shunt Calibration Equation for the Half-Bridge Bending Configuration . . . . . . 102
Shunt Calibration Equation for the Full-Bridge Bending Configuration . . . . . . 103
Shunt Calibration Equation for the Full-Bridge Bending Poisson
Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Shunt Calibration Equation for the Full-Bridge Axial Poisson Configuration . 103
Offset Nulling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
TEDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Input Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Input Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
A/D Sample Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Analog Input Conversion Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Single-Value Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Continuous Scan Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Input Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Start Trigger Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Reference Trigger Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Tachometer Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Synchronizing Acquisition on Multiple Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Triggering DT9838 and DT9837 Series Modules Using the Sync Bus . . . . . . . . . . . . . 114
Chapter 6: Supported Device Driver Capabilities. . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Data Flow and Operation Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Triggered Scan Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Data Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Current and Resistance Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Thermocouple, RTD, and Thermistor Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
IEPE Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Bridge and Strain Gage Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Start Triggers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Reference Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

7

Contents
Counter/Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Tachometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Chapter 7: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
General Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
If Your Module Needs Factory Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Chapter 8: Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Using the Calibration Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Calibrating the Analog Input Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Connecting a Precision Voltage Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Using the Auto-Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Using the Manual Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Calibrating the Internal Analog Output Circuity (Excitation Voltage) . . . . . . . . . . . . . . . 139
Connecting a Digital Voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Calibrating the Analog Output Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Appendix A: Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Analog Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Bridge Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Tachometer Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Trigger Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Power, Physical, and Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Regulatory Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Connector Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
External Power Supply Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Appendix B: Connector Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Analog Input Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Sync Bus Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
External Trigger and Tachometer Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
External USB Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
External Power Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Screw Terminals on the STP STRAIN, STP STRAIN 120, and STP STRAIN 350 . . . . . . . 157
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

8

About this Manual
The first part of this manual describes how to install and set up your DT9838 module anddevice driver, and verify that your module is working properly.
The second part of this manual describes the features of the DT9838 module, the capabilities of
the DT9838 Device Driver, and how to program the DT9838 module using DT-Open Layers
for .NET Class Library software. Troubleshooting information is also provided.

Notes: For more information on the class library, refer to the DT-Open Layers for .NET Class
Library User’s Manual. If you are using the DataAcq SDK or a software application to program
your device, refer to the documentation for that software for more information.

Intended Audience
This document is intended for engineers, scientists, technicians, or others responsible for
installing, setting up, using, and/or programming DT9838 modules for data acquisition
operations.
It is assumed that you are familiar with the requirements of your application. It is also
assumed that you have some familiarity with data acquisition principles, that you understandyour application, and that you are familiar with the Microsoft Windows Vista, Windows 7,
Windows 8, or Windows 10 operating system.

How this Manual is OrganizedThis manual is organized as follows:• Chapter 1, “Overview,” describes the major features of the DT9838 module, as well as the
supported software and accessories for the modules.
• Chapter 2, “Setting Up and Installing the Module,” describes how to apply power to themodule, how to attach the module to your computer, and how to configure the device
driver.
• Chapter 3, “Wiring Signals,” describes how to wire signals to the DT9838 module.
• Chapter 4, “Verifying the Operation of a Module,” describes how to verify the operationof the module with the QuickDAQ application.
• Chapter 5, “Principles of Operation,” describes all of the features of the module and how
to use them in your application.
• Chapter 6, “Supported Device Driver Capabilities,” lists the data acquisition subsystems
and the associated features accessible using the DT9838 Device Driver.
• Chapter 7, “Troubleshooting,” provides information that you can use to resolve problems
with the module and device driver, should they occur.

9

About this Manual• Chapter 8, “Calibration,” describes how to calibrate the analog I/O circuitry of themodule.
• Appendix A, “Specifications,” lists the specifications of the DT9838 module.
• Appendix B, “Connector Pin Assignments,” shows the pin assignments of the connectors
on the DT9838 module.
• An index completes this manual.

Conventions Used in this Manual
The following conventions are used in this manual:• Notes provide useful information that requires special emphasis, cautions provide
information to help you avoid losing data or damaging your equipment, and warnings
provide information to help you avoid catastrophic damage to yourself or yourequipment.
• Items that you select or type are shown in bold.
• Courier font is used to represent source code.

Related Information
Refer to the following documents for more information on using the DT9838 module:• QuickDAQ User’s Manual (UM-24774). This manual describes how to create a QuickDAQ
application to acquire and analyze data from DT-Open Layers data acquisition devices.
• DT-Open Layers for .NET User’s Manual (UM-22161). For programmers who aredeveloping their own application programs using Visual C# or Visual Basic .NET, thismanual describes how to use the DT-Open Layers for .NET Class Library to access thecapabilities of Data Translation data acquisition devices.
• DataAcq SDK User’s Manual (UM-18326). For programmers who are developing their own
application programs using the Microsoft C compiler, this manual describes how to use
the DT-Open LayersTM DataAcq SDKTM to access the capabilities of Data Translation dataacquisition devices.
• LV-Link Online Help. This help file describes how to use LV-Link with the LabVIEW
graphical programming language to access the capabilities of Data Translation dataacquisition devices.
• DAQ Adaptor for MATLAB (UM-22024). This document describes how to use Data
Translation’s DAQ Adaptor to provide an interface between the MATLAB Data
Acquisition subsystem from The MathWorks and Data Translation’s DT-Open Layers
architecture.
• Microsoft Windows Vista, Windows 7, Windows 8, or Windows 10 documentation.
• USB web site (http://www.usb.org)

10About this Manual

Where To Get Help
Should you run into problems installing or using a DT9838 module, the Technical Support
Department is available to provide technical assistance. Refer to Chapter 7 starting on page
129 for information. If you are outside the United States or Canada, call your local distributor,
whose number is listed on our web site www.mccdaq.com.

11About this Manual12

1Overview
DT9838 Hardware Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Supported Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Supported Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Getting Started Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

13

Chapter 1

DT9838 Hardware Features
The DT9838 module, shown in Figure 1, is a USB strain gage measurement device intended
for full-, half, and quarter-bridge strain gage elements and bridge-based sensor assemblies
such as load cells, torque sensors, and pressure sensors, as well as general-purpose voltage
measurements. It is compatible with USB 2.0 and USB 1.1 ports.

Figure 1: DT9838 Module

The key hardware features of the DT9838 are as follows:• Simultaneous measurement of four 24-bit analog input channels and one tachometer in
the analog input stream• Direct full-bridge and half-bridge support with half-bridge completion• Quarter-bridge support with external bridge-completion resistor• Load cell support• Non-bridged voltage input configuration• Programmable input and bridge configuration• Internal bridge excitation of 0 to 10 V in 167 V steps• Programmable 100 k ±0.1% shunt resistor per channel• TEDS (IEEE 1451.4) sensor compatible• Software calibration of the bridge offset and gain
• Sampling frequency from 195.3125 Hz to 52.734 kHz• Input range of ±250 mV

14

Overview• Continuously paced analog input operations• Software-programmable trigger type (software, external digital trigger, or variable digital
threshold trigger) to start analog input operations• Sync Bus (RJ45) connector for synchronizing acquisition on up to four DT9838 modules• LEDs for monitoring the arm/trigger state and USB status

Note: A board-level version of this module (without the enclosure) is also available for OEM
applications.

15

Chapter 1

Supported Software
The DT Omni installer includes the following software for use with the DT9838 module:• DT9838 Device Driver – The DT9838 Device Driver allows you to use a DT9838 modulewith any of the supported software packages or utilities.
• QuickDAQ Base Version – The base version of QuickDAQ is free-of-charge and allows
you to acquire and analyze data from all Data Translation USB and Ethernet devices,
except the DT9841 Series, DT9817, DT9835, and DT9853/54. Using the base version of
QuickDAQ, you can perform the following functions: Discover and select your devices.
 Configure all input channel settings for the attached sensors.
 Load/save multiple hardware configurations.
 Generate output stimuli (fixed waveforms, swept sine waves, or noise signals).
 On each supported data acquisition device, acquire data from all channels supported
in the input channel list.
 Choose to acquire data continuously or for a specified duration.
 Choose software or triggered acquisition.
 Log acquired data to disk in an .hpf file.
 Display acquired data during acquisition in either a digital display using the Channel
Display window or as a waveform in the Channel Plot window.
 Choose linear or logarithmic scaling for the horizontal and vertical axes.
 View statistics about the acquired data, including the minimum, maximum, and meanvalues and the standard deviation in the Statistics window.
 Export time data to a .csv or .txt file; you can open the recorded data in Microsoft
Excel® for further analysis.
 Read a previously recorded .hpf data file.
 Customize many aspects of the acquisition, display, and recording functions to suit
your needs, including the acquisition duration, sampling frequency, trigger settings,
filter type, and temperature units to use.
• QuickDAQ FFT Analysis Option – When enabled with a purchased license key, theQuickDAQ FFT Analysis option includes all the features of the QuickDAQ Base version
plus basic FFT analysis features, including the following: The ability to switch between the Data Logger time-based interface and the FFT
Analyzer block/average-based interface.
 Supports software, freerun, or triggered acquisition with accept and reject controls for
impact testing applications.
 Allows you to perform single-channel FFT (Fast Fourier Transform) operations,
including AutoSpectrum, Spectrum, and Power Spectral Density, on the acquired
analog input data. You can configure a number of parameters for the FFT, including
the FFT size, windowing type, averaging type, integration type, and so on.
 Allows you to display frequency-domain data as amplitude or phase.

16

Overview Supports dB or linear scaling with RMS (root mean squared), peak, and peak-to-peakscaling options
 Supports linear or exponential averaging with RMS, vector, and peak hold averaging
options.
 Supports windowed time channels.
 Supports the following response window types: Hanning, Hamming, Bartlett,Blackman, Blackman Harris, and Flat top.
 Supports the ability to lock the waveform output to the analysis frame time.
 Allows you to configure and view dynamic performance statistics, including the input
below full-scale (IBF), total harmonic distortion (THD), spurious free dynamic range(SFDR), signal-to-noise and distortion ratio (SINAD), signal-to-noise ratio (SNR), andthe effective number of bits (ENOB), for selected time-domain channels in the Statistics
window.
 Supports digital IIR (infinite impulse response) filters.
• QuickDAQ Advanced FFT Analysis Option – When enabled with a purchased software
license, the QuickDAQ Advanced FFT Analysis option includes all the features of the
QuickDAQ Base version with the FFT Analysis option plus advanced FFT analysis
features, including the following: Allows you to designate a channel as a Reference or Response channel.
 Allows you to perform two-channel FFT analysis functions, including Frequency
Response Functions (Inertance, Mobility, Compliance, Apparent Mass, Impedance,
Dynamic Stiffness, or custom FRF) with H1, H2, or H3 estimator types,
Cross-Spectrum, Cross Power Spectral Density, Coherence, and Coherent Output
Power.
 Supports the Exponential response window type.
 Supports the following reference window types: Hanning, Hamming, Bartlett,Blackman, Blackman Harris, FlatTop, Exponential, Force, and Cosine Taper windows.
 Supports real, imaginary, and Nyquist display functions.
 Allows you to save data in the .uff file format.
• DT-Open Layers for .NET Class Library – Use this class library if you want to use Visual
C# or Visual Basic for .NET to develop your own application software for a DT9838
module using Visual Studio 2003 to 2012; the class library complies with the DT-Open
Layers standard.
• DataAcq SDK – Use the Data Acq SDK if you want to use Visual Studio 6.0 and Microsoft
C or C++ to develop your own application software for a DT9838 module using Windows
Vista, Windows 7, or Windows 8; the DataAcq SDK complies with the DT-Open Layers
standard.
• DAQ Adaptor for MATLAB – A link to the DAQ Adaptor for MATLAB is included fromthe DT Omni installer. Data Translation’s DAQ Adaptor provides an interface between
the MATLAB Data Acquisition (DAQ) subsystem from The MathWorks and Data
Translation’s DT-Open Layers architecture.

17

Chapter 1• LV-Link – A link to LV-Link is included from the DT Omni installer. Use LV-Link if you
want to use the LabVIEW graphical programming language to access the capabilities of
the DT9838 module.
Refer to the web site www.mccdaq.com for information about selecting the right software
package for your needs.

18OverviewSupported Accessories
The following accessories are available for the DT9838 module:• STP STRAIN General-Purpose Accessory – This accessory contains four
general-purpose screw terminal panels. Use one screw terminal panel for each channel.

Figure 2: STP STRAIN General-Purpose Accessory• STP STRAIN 120 Quarter-Bridge Completion Accessory – This accessory contains fourscrew terminal panels with a 120 quarter-bridge completion resistor installed on eachscrew terminal panel. Use one screw terminal panel for each channel.

Figure 3: STP STRAIN 120 Quarter-Bridge Completion Accessory

19Chapter 1• STP STRAIN 350 Quarter-Bridge Completion Accessory – This accessory contains fourscrew terminal panels with a 350 quarter-bridge completion resistor installed on eachscrew terminal panel. Use one screw terminal panel for each channel.

Figure 4: STP STRAIN 350 Quarter-Bridge Completion Accessory• EP398 RJ50 cables – The EP398 accessory contains four RJ50 cables that are used toconnect four STP STRAIN, STP STRAIN 120, or STP STRAIN 350 screw terminal panels to
the DT9838 module. Figure 5 shows an RJ50 cable.

Figure 5: RJ50 Cable

20

Overview• EP394 +5 V external power supply – Use this optional power supply, shown in Figure 6,
if you want to use an external +5 V power supply to power the DT9838 module. Refer topage 29 for information on using internal USB power or external +5 V power to power theDT9838 module.

Figure 6: EP394 External +5 V Power Supply• EP386 panel – The EP386 panel, shown in Figure 7, contains four RJ45 connectors that are
wired in parallel, making it useful when attaching up to four DT9838 modules together
using the Sync Bus. Refer to page 112 for more information on using this panel.

Figure 7: EP386 Panel

21

Chapter 1

Getting Started Procedure
The flow diagram shown in Figure 8 illustrates the steps needed to get started using theDT9838 module. This diagram is repeated in each Getting Started chapter; the shaded area inthe diagram shows you where you are in the procedure.

Set Up and Install the Module(see Chapter 2 starting on page 25)
Wire Signals(see Chapter 3 starting on page 35)

Verify the Operation of the Module(see Chapter 4 starting on page 71)

Figure 8: Getting Started Flow Diagram

22

Part 1: Getting Started

2
Setting Up and Installing the Module
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
(Optional) Applying Power to the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Attaching Modules to the Computer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Configuring the DT9838 Device Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

25

Chapter 2

Set Up and Install the Module(this chapter)
Wire Signals(see Chapter 3 starting on page 35)

Verify the Operation of the Module(see Chapter 4 starting on page 71)

Note: The DT9838 module is factory-calibrated. If you decide that you want to recalibrate
the analog input circuitry, refer to the instructions on Chapter 8.

26

Setting Up and Installing the Module

UnpackingOpen the shipping box and verify that the DT9838 module is missing and undamaged.
If the module is damaged, contact Data Translation. If you are in the United States, call the
Customer Service Department at (508) 956-5100. An application engineer will guide you
through the appropriate steps for replacing damaged items. If you are located outside theUnited States, call your local distributor (see www.mccdaq.com for more information).

27

Chapter 2

System Requirements
For reliable operation, ensure that your computer meets the following system requirements:• Processor: Pentium 4/M or equivalent• RAM: 1 GB
• Screen Resolution: 1024 x 768 pixels• Operating System: Windows 10, Windows 8, Windows 7, or Windows Vista (32- and64-bit)• Disk Space: 4 GB

28

Setting Up and Installing the Module(Optional) Applying Power to the Module
The DT9838 is designed to operate from USB power alone. However, the number of channels
that it can power is limited by the USB port power capability, the programmed excitation
voltage, and the bridge resistance. To enhance the bridge drive capability, you can purchasethe optional +5 V power supply (model number EP394) available from Data Translation or use
an external +5 to +24 VDC power supply to power the DT9838 module.
Table 1 shows the number of channels that are supported when the module is powered with
USB power or external power, given different bridge configurations and excitation voltages.
Table 1: Number of Channels Supported when Module is Powered with USB Power or External Power

BridgeConfiguration
Full Bridge

Quarter Bridge
andHalf Bridge

USB Power Supplied

5 V to 24 V External Power Supplied

Bridge ResistanceBridge Resistance

Excitation
Voltage

120 

350 

1 k

120 

350 

1 k

2.5 V

3 channels

4 channels

4 channels

4 channels

4 channels

4 channels

3.3 V

2 channels

4 channels

4 channels

4 channels

4 channels

4 channels

5V–

4 channels

4 channels–

4 channels

4 channels

10 V

–

1 channel

3 channels–

4 channels

4 channels

2.5 V

4 channels

4 channels

4 channels

4 channels

4 channels

4 channels

3.3 V

4 channels

4 channels

4 channels

4 channels

4 channels

4 channels

5V

3 channels

4 channels

4 channels

4 channels

4 channels

4 channels

10 V

–

2 channel

4 channels–

4 channels

4 channels

To attach an external power supply to the module, do the following:
1. Connect the +5 V power supply (EP394) to the auxiliary power connector on the DT9838
module, as shown in Figure 9.
2. Plug the power supply into a wall outlet.

29

Chapter 2

Auxiliary Power
Connector

DT9838 ModuleEP394 +5 VPower

To wall outlet

Figure 9: Attaching an External +5 V Power Supply to the DT9838 Module

30

Setting Up and Installing the Module

Attaching Modules to the ComputerThis section describes how to attach DT9838 modules to the host computer.

Note: Most computers have several USB ports that allow direct connection to USB devices.
If your application requires more DT9838 modules than you have USB ports for, you can
expand the number of USB devices attached to a single USB port by using expansion hubs.
For more information, refer to page 32.
You can unplug a module, then plug it in again, if you wish, without causing damage. This
process is called hot-swapping. Your application may take a few seconds to recognize amodule once it is plugged back in.

You must install the device driver before connecting your DT9838 module(s) to the hostcomputer. Run the DT Omni software to install the device driver and other software for themodule.

Connecting Directly to the USB Ports
To connect a DT9838 module directly to a USB port on your computer, do the following:
1. Attach one end of the USB cable to the USB port on the module.
2. Attach the other end of the USB cable to one of the USB ports on the host computer, as
shown in Figure 10.
The operating system automatically detects the USB module and starts the Found New Hardware
wizard.

Trigger LED
USB
Port

DT9838 Module

USB LED

Connect the USB cable to the DT9838
module and to your computer.

Figure 10: Attaching the DT9838 Module to the Host Computer

31

Chapter 2
3. For Windows Vista:
a. Click Locate and install driver software (recommended).
The popup message "Windows needs your permission to continue" appears.
b. Click Continue.
The Windows Security dialog box appears.
c.

Click Install this driver software anyway.
The USB LED on the module turns green.

Note: Windows 7, Windows 8, and Windows 10 find the device automatically.

4. Repeat these steps to attach another DT9838 module to the host computer, if desired.

Connecting to an Expansion Hub
Expansion hubs are powered by their own external power supply. The practical number ofDT9838 modules that you can connect to a single USB port depends on the throughput you
want to achieve.
To connect multiple DT9838 modules to an expansion hub, do the following:
1. Attach one end of the USB cable to the module and the other end of the USB cable to an
expansion hub.
2. Connect the power supply for the expansion hub to an external power supply.
3. Connect the expansion hub to the USB port on the host computer using another USB
cable.
The operating system automatically detects the USB module and starts the Found New Hardware
wizard.
4. For Windows Vista:
a. Click Locate and install driver software (recommended).
The popup message "Windows needs your permission to continue" appears.
b. Click Continue.
The Windows Security dialog box appears.
c.

Click Install this driver software anyway.
The USB LED on the module turns green.

Note: Windows 7, Windows 8, and Windows 10 find the device automatically.

5. Repeat these steps until you have attached the number of expansion hubs and modules
that you require. Refer to Figure 11.
The operating system automatically detects the USB devices as they are installed.

32

Setting Up and Installing the Module

DT9838ModuleUSB Cables

DT9838ModuleHost Computer
USB Cable

USB Cable
Power Supply
for Hub

Expansion Hubs
Power Supply
for Hub
DT9838ModuleDT9838ModuleUSB Cables

Figure 11: Attaching Multiple Modules Using Expansion Hubs

33

Chapter 2

Configuring the DT9838 Device Driver
Note: In Windows, you must have administrator privileges to run the Open Layers Control
Panel. When you double-click the Open Layers Control Panel icon, you may see the Program
Compatibility Assistant. If you do, select Open the control panel using recommended
settings. You may also see a Windows message asking you if you want to run the Open
Layers Control Panel as a "legacy CPL elevated." If you get this message, click Yes.
If you do not get this message and have trouble making changes in the Open Layers Control
Panel, right click the DTOLCPL.CPL file and select Run as administrator. By default, this fileis installed in the following location:
Windows (32-bit)
C:\Windows\System32\Dtolcpl.cpl
Windows (64-bit)
C:\Windows\SysWOW64\Dtolcpl.cpl

To configure the device driver for the DT9838 module, do the following:
1. If you have not already done so, power up the host computer and all peripherals.
2. From the Windows Start menu, select Settings|Control Panel.
3. From the Control Panel, double-click Open Layers Control Panel.
The Data Acquisition Control Panel dialog box appears.
4. If you want to rename the module, click the name of the module that you want to rename,click Edit Name, enter a new name for the module, and then click OK. The name is used
to identify the module in all subsequent applications.
5. Repeat step 4 for the other modules that you want to configure.
6. When you are finished configuring the modules, click Close to close the Control Panel.

34

3
Wiring Signals
Preparing to Wire Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Connecting a General-Purpose or Bridge-Completion Accessory . . . . . . . . . . . . . . . . . . . . 40
Connecting Quarter-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Connecting Half-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Connecting Full-Bridge Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Connecting Load Cells and Other Transducers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Connecting Voltage Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Connecting a Tachometer Input Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Connecting an External Trigger Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

35

Chapter 3

Set Up and Install the Module(see Chapter 2 starting on page 25)
Wire Signals(this chapter)

Verify the Operation of the Module(see Chapter 4 starting on page 71)

36

Wiring Signals

Preparing to Wire Signals
Figure 12 shows the connectors of the DT9838 module. The left side of the DT9838 module
contains four analog input (RJ50) connectors for connecting strain gages, load cells and othersensors, and/or voltage input signal. The right side of the DT9838 module provides thefollowing connectors:• Auxiliary power connector – Allows you to attach the optional EP394 external power
supply.
• External trigger and tachometer connector – Provides screw terminals for connecting an
external trigger and/or tachometer input signal.
• Sync Bus connector – Allows you to attach multiple modules together.
• USB connector – Allows you to attach the DT9838 module to your computer.

A/D
Chan 0

A/D
Chan 1

A/D
Chan 2

A/D
Chan 3

Trigger LED
USB
Port

Auxiliary Power
Connector

Ext Trigger
andTachometer

Sync Bus
USB LED

Figure 12: Connectors on the DT9838 Module (Side Views)

37

Chapter 3

General Wiring Recommendations
Keep the following recommendations in mind when wiring signals to the DT9838 module:• Follow standard ESD procedures when wiring signals to the module.
• Separate power and signal lines by using physically different wiring paths or conduits.
• To avoid noise, do not locate the DT9838 module and cabling next to sources that produce
high electromagnetic fields, such as large electric motors, power lines, solenoids, andelectric arcs, unless the signals are enclosed in a mumetal shield.
• Prevent electrostatic discharge to the I/O while the DT9838 module is operational.
• Use an overall shielded cable for connections between the strain gages and the DT9838,
with the shield connected to the chassis ground connection of the DT9838. A shieldconnection point is provided on pin 11 of the STP STRAIN, STP STRAIN 120, and STP
STRAIN 350 accessories.
• Use individually shielded twisted-pair wire (size 14 to 26 AWG) when wiring voltage
input signals to the DT9838 module.

Definitions
The following terms are used in this chapter:•  is the measured strain (+ is the tensile strain and – is the compressive strain)• is the Poisson’s ratio, defined as the negative ratio of transverse strain to axial(longitudinal) strain• RL is the lead resistance• Rg is the nominal gage resistance, which is specified by the gage manufacturer

38

Wiring Signals

Analog Input Connector Pin Assignments (RJ50 Connector)
For analog input channels 0 to 3, the DT9838 module provides RJ50 connectors, shown in
Figure 13, for connecting strain gages, load-cell sensors, and/or voltage inputs. Table 2 lists
the pin assignments for the RJ50 connectors.

1 2 3 4 5 6 7 8 9 10

Figure 13: Analog Input (RJ50) Connector

Table 2: Pin Assignments for the RJ50 Connectors
Pin

Signal Description

1

RSHUNT+

2

AIN+

3

AIN–

4

SENSE+

5

SENSE–

6

EXC+

7

EXC–

8

TEDS DATA9TEDS RETURN

10RSHUNT –39

Chapter 3

Connecting a General-Purpose or Bridge-Completion
Accessory
To make wiring bridges easier, you may want to purchase one of the following optional
accessories:• STP STRAIN General-Purpose Accessory – This accessory contains four
general-purpose screw terminal panels. Use one screw terminal panel for each channel.
• STP STRAIN 120 Quarter-Bridge Completion Accessory – This accessory contains fourscrew terminal panels with a 120 quarter-bridge completion resistor installed on eachscrew terminal panel. Use one screw terminal panel for each channel.
• STP STRAIN 350 Quarter-Bridge Completion Accessory – This accessory contains fourscrew terminal panels with a 350 quarter-bridge completion resistor installed on eachscrew terminal panel. Use one screw terminal panel for each channel.
Figure 14 shows the layout of the STP STRAIN, STP STRAIN 120, and STP STRAIN 350
accessories.

Connect bridge signals to thescrew terminals
Screw Terminal 1
External bridge completion
resistors are provided on the
STP STRAIN 120 and STP
STRAIN 350 accessories.

Connect the
RJ50 cable to
the DT9838

Figure 14: Layout of the STP STRAIN, STP STRAIN 120, and STP STRAIN 350 Accessories

The screw terminal assignments of the STP STRAIN, STP STRAIN 120, and STP STRAIN 350
screw terminal panels, listed in Table 3, match the pin designations of the RJ50 analog input
connectors on the DT9838.

40

Wiring Signals
Table 3: Pin Assignments for the STP STRAIN, STP STRAIN 120,and STP STRAIN 350 Screw Terminal Panels
Pin

Signal Description

1

Shunt Cal+

2

Input+

3

Input–

4

Sense+

5

Sense–

6

Excitation+

7

Excitation–

8

TEDS+ (Data)

9

TEDS– (Return)10

Shunt Cal–

11

ShieldThe optional EP398 contains four RJ50 cables. Use an RJ50 cable to connect the RJ50 connector
on the STP STRAIN, STP STRAIN 120, or STP STRAIN 350 screw terminal panel to the RJ50
connector on the DT9838 module, as shown in Figure 15.

Figure 15: Connecting the STP STRAIN, STP STRAIN 120, or STP STRAIN 350 Accessory to theDT9838 Module

41

Chapter 3

Connecting Quarter-Bridge Circuits
The DT9838 module supports the following quarter-bridge configurations:• Quarter-Bridge (Axial and Bending)• Quarter-Bridge Temp Comp
This section describes how to wire the Quarter-Bridge and Quarter-Bridge Temp Compcircuits to the DT9838 module. For more information about these bridge configuration types,
refer to page 94.

Wiring a Quarter-Bridge (Axial and Bending) Circuit
The Quarter-Bridge configuration, shown in Figure 16, measures axial or bending strain.

R4 (+)StrainGage

R4 (+)StrainGage

Bending

Axial

Figure 16: Quarter-Bridge Configuration

The Quarter-Bridge configuration has the following characteristics:• A single active strain gage element is mounted in the direction of axial or bending strain.
• You must supply a resistor (R) that matches the nominal resistance of the bridge tocomplete the bridge externally. This is supplied for you when you use the STP STRAIN
120 or STP STRAIN 350 quarter-bridge completion accessory.

42

Wiring Signals

Note: In some cases, you may wish to use a rosette, which is arrangement of two or threeclosely positioned strain gage grids that are oriented to measure the normal strains along
different directions in the underlying surface of a test material. The DT9838 supports
rectangular and delta rosettes; tee rosettes are not supported.
A rectangular rosette is an arrangement of three strain gage grids where the second grid isangularly displaced from the first grid by 45 degrees and the third grid is angularly displaced
from the first grid by 90 degrees. A delta rosette is an arrangement of three strain gage grids
where the second grid is angularly displaced from the first grid by 60 degrees and the third
grid is angularly displaced from the first grid by 120 degrees.
To use a rectangular or delta rosette, use the Quarter-Bridge configuration with the proper
bridge completion. You can then read the strain value from each analog input channel
individually, and if desired, use software to calculate the minimum and maximum principal
strain values and their associated angles (in degrees).

Figure 17 shows how to connect a 3-wire Quarter-Bridge circuit to the STP STRAIN 120 or STP
STRAIN 350 quarter-bridge completion accessory. Remote sense lines (SENSE+ and SENSE–)
are not used in the 3-wire connection scheme using the STP STRAIN 120 or STP STRAIN 350
quarter-bridge completion accessories; therefore, the remote sense lines are connected to theexcitation lines (SENSE+ is connected to EXC+ and SENSE– is connected to EXC–) to ensure
proper bridge voltage regulation. If the lead wire resistance is known, you can enter the leadwire correction coefficient in software. Refer to page 100 for more information.

43

Chapter 3

RL

R4

EXC+

6

EXC+

6

SENSE+

4

DT9838BridgeExcitation

+e

AIN+

k
1010kO
R1

2

AIN+
AIN-

2
3

+
k
1010kO
R2

RL

QTR

1

R3*

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1

Quarter-Bridge
Completion
Accessory
RJ50

8
9

ADC
24-bitPrecision
Instrumentation Amp

100kO
k
100

TEDS
SER

RJ50

*With the STP STRAIN 120 quarter-bridge completion accessory, thevalue of resistor R3 is 120  to match the value of resistor R4.
With the STP STRAIN 350 quarter-bridge completion accessory, thevalue of resistor R3 is 350  to match the value of resistor R4.

Figure 17: Connecting a Quarter-Bridge Circuit to the DT9838 When Using the STP STRAIN 120 or
STP STRAIN 350 Quarter-Bridge Completion Accessory

Figure 18 shows how to connect a Quarter Bridge circuit to the DT9838 when using thegeneral-purpose STP STRAIN accessory. In this example, the user-supplied resistor ismounted at the strain gage and the remote sense lines (SENSE+ and SENSE–) are not used;
therefore, the remote sense lines are connected to the excitation lines (SENSE+ is connected to
EXC+ and SENSE– is connected to EXC–) to ensure proper bridge voltage regulation. If thelead wire resistance is known, you can enter the lead wire correction coefficient in software.
Refer to page 100 for more information.

44

Wiring Signals

RL

R4

General-Purpose STP STRAIN
Accessory Connected to DT9838

EXC+

6

SENSE+

4
10 kΩ
k
10
R1


AIN+
AIN-

2
3

R3
(User Supplied)
RL
RL
RL

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1
8
9

BridgeExcitation+k
1010kΩ
R2

ADC
24-bitPrecision
Instrumentation Amp

100kΩ
k
100

TEDS
SER

RJ50

Figure 18: Connecting a Quarter-Bridge Circuit to the DT9838 and General-Purpose STP STRAIN
Accessory when the Completion Resistor is Mounted at the Strain Gage

Remote Sensing In Quarter-Bridge Configurations
Remote sensing is not used in the 3-wire Quarter-Bridge configurations that use the STP
STRAIN 120 and STP STRAIN 350 quarter-bridge completion accessories, as shown in Figure
17. However, you may want to use the remote sense lines (SENSE+ and SENSE–) in some
applications that use Quarter-Bridge configurations, particularly where long wires and/or
small gauge wires are used, to minimize voltage drops caused by the lead wire resistance of
the EXC+ and EXC– lines.
Figure 19 shows how to connect a Quarter Bridge circuit to the DT9838 using remote senselines. In this example, the general-purpose STP STRAIN accessory is used and theuser-supplied resistor is mounted at the strain gage.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

45

Chapter 3

RL

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC+

6

SENSE+

4
10kO
k
10
R1

R4 
AIN+
R3

AIN-

2
3

(User
R
Supplied) L

SENSEEXC-

7RL

RSHUNT-

10

RSHUNT+

1

RL

5

8
9

BridgeExcitation+k
1010kO
R2

ADC
24-bitPrecision
Instrumentation Amp

100kO
k
100

TEDS
SER

Figure 19: Connecting a Quarter-Bridge Circuit to the DT9838 and General-Purpose STP STRAIN
Accessory when the Completion Resistor is Mounted at the Strain Gage and theRemote Sense Lines are Used

Shunt Calibration in Quarter-Bridge Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 102 for the equations used forshunt calibration in Quarter-Bridge configurations.
To perform shunt calibration in a Quarter-Bridge configuration, the RSHUNT+ and
RSHUNT– lines for the internal 100 k shunt resistor are connected either across R or R ofthe connected bridge. However, when using the STP STRAIN 120 or STP STRAIN 350 bridge
completion accessory, as shown in Figure 17, the shunt resistor can only be connected acrossR. Figure 18 and Figure 19 show how to connect the RSHUNT+ and RSHUNT– lines whenusing the general-purpose STP STRAIN accessory.
In either case, while the bridge is in the unstrained condition, you can use software to switch
in the shunt calibration resistor to simulate a known amount of strain. The measured output
value with the shunt resistor in place is then compared to the expected value of strain with theshunt resistor in place. The gain of the bridge transfer function is then modified by the ratio of
the expected strain to the measured strain, calibrating the system. Refer to your software
documentation for more information about shunt calibration
Once you have verified your setup, you can disconnect the RSHUNT+ and RSHUNT– lines, if
desired.

46

Wiring Signals

Wiring a Quarter-Bridge Temp Comp Circuit
The Quarter-Bridge Temp Comp configuration, shown in Figure 20, measures axial andbending strain and compensates for temperature.

Note: This configuration is often confused with the more commonly used Half-Bridge
Poisson configuration, described on page 50. In the Half-Bridge Poisson configuration, the R3
element is active and is bonded to the strain specimen to measure the effect of the Poisson
ratio. In the Quarter-Bridge Temp Comp configuration, R3 is not active (a dummy strain gageis used) and is not bonded to the specimen.

R4 (+)ActiveStrainGage

R4 (+)Dummy
StrainGage

ActiveStrain
Gage
R3
Dummy
StrainGage

Bending

R3
Axial

Figure 20: Quarter-Bridge Temp Comp Configuration

The Quarter-Bridge Temp Comp configuration has the following characteristics:• Uses active strain gage element and one passive (dummy) strain gage element.
• The active strain gage element is mounted in the direction of axial or bending strain.
• The passive (dummy) strain gage element, R,is mounted in close thermal contact withthe strain specimen to compensate for temperature, but is not bonded to the specimen; it
does not respond to the axial or bending strain of the specimen.
Although it is not necessary, the dummy strain gage element is usually mounted
perpendicular to the axis of strain.

47

Chapter 3
Figure 22 shows how to connect a Quarter-Bridge Temp Comp circuit to the DT9838 whenusing the general-purpose STP STRAIN accessory and remote sensing.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC+
SENSE+

6
4
10 kΩ
k
10
R1

R4



AIN+

2

AIN-

3

R3
(Dummy)RL
RL

BridgeExcitation

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1
8
9

+
k
1010kΩ
R2

ADC
24-bitPrecision
Instrumentation Amp

100 kΩ
k
100

TEDS
SER

RJ50

Figure 21: Connecting a Quarter Bridge Temp Comp Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

Remote Sensing In Quarter-Bridge Temp Comp Configurations
Although not required for operation in Quarter-Bridge Temp Comp configurations, it isrecommended that you connect the bridge SENSE+ and SENSE– lines, as shown in Figure 21
to minimize voltage drops caused by the lead wire resistance of the EXC+ and EXC– lines.
This is most important in applications where long wires and/or small gauge wires, whichhave greater resistance, are used.
If you do not use remote sense leads, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 22, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.

48

Wiring Signals

RL

General-Purpose STP STRAIN
Accessory Connected to DT9838

EXC+

6

SENSE+

4



10 k

BridgeExcitation

R1

R4
AIN+
AIN-

2
3

R3
(Dummy)
RL
RL
RL

+
10 k

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1
8
9

R2

ADC
24-bitPrecision
Instrumentation Amp

100 k

TEDS
SER

RJ50

Figure 22: Connecting a Quarter Bridge Temp Comp Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

Shunt Calibration in Quarter-Bridge Temp Comp Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 102 for the equations used forshunt calibration in Quarter-Bridge Temp Comp configurations.
To perform shunt calibration in a quarter-bridge configuration using the internal 100 k
resistor, connect the internal RSHUNT+ and RSHUNT– lines across gage RorR, as shown in
Figure 21 and Figure 22. You can then use software to switch in 100 k across gage RorRwhen no strain is applied to the specimen, creating a known change in the bridge output. You
can then use software to measure the output of the bridge, compare it to the expected bridge
output value, and adjust the gain of the DT9838 to compensate for these errors.
Once you have verified your setup, you can disconnect the RSHUNT+ and RSHUNT– lines, if
desired.
Refer to your software documentation for more information about shunt calibration.

49

Chapter 3

Connecting Half-Bridge Circuits
The DT9838 module supports the following half-bridge configurations:• Half-Bridge Poisson (Bending or Axial)• Half-Bridge Bending
This section describes how to wire the Half-Bridge Poisson and Half-Bridge Bending circuits
to the DT9838 module. The wiring diagram is the same for all half-bridge configurations;however, the meaning of R and R differs depending on the configuration you choose. For
more information about these bridge configuration types, refer to page 95.

Wiring a Half-Bridge Poisson Circuit
The Half-Bridge Poisson configuration, shown in Figure 23, measures either axial or bendingstrain, compensates for temperature, and compensates for the aggregate effect on the principle
strain measurement due to the Poisson ratio of the specimen material.

R4 (+)StrainGage

R4 (+)StrainGage
StrainGage

StrainGage

R3 (–)R3 (–)Bending

Axial

Figure 23: Half-Bridge Poisson Configuration50

Wiring Signals
The Half-Bridge Poisson configuration has the following characteristics:• Uses two active strain gage elements.
• One strain gage element, R4 (+, is mounted in the direction of axial strain.
The other strain gage element, R3 (–), is mounted transversely (perpendicular) to theaxis of strain to measure the Poisson effect.
• The DT9838 provides two internal 10 k resistors R1 and R2, to complete the sensor side of
the bridge circuit.
Figure 24 shows how to connect a Half-Bridge Poisson circuit to the DT9838 when using thegeneral-purpose STP STRAIN accessory and remote sensing.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC+
SENSE+

64k
1010kΩ
R1

R4 
AIN+
R3 RL
RL

BridgeExcitation

AIN-

2
3

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1
8
9

+
10kΩ
k
10
R2

ADC
24-bitPrecision
Instrumentation Amp

100 k
100kΩ

TEDS
SER

RJ50

Figure 24: Connecting a Half-Bridge Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

51

Chapter 3

Remote Sensing In Half-Bridge Poisson Configurations
Although not required for operation in Half-Bridge Poisson configuration, it is recommended
that you connect the bridge SENSE+ and SENSE– lines, as shown in Figure 24 to minimize
voltage drops caused by the lead wire resistance of the EXC+ and EXC– lines. This is mostimportant in applications where long wires and/or small gauge wires, which have greater
resistance, are used.
If you do not use remote sense lines, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 25, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.
General-Purpose STP STRAIN
Accessory Connected to DT9838
RL

EXC+
SENSE+

6
4

BridgeExcitation
10 kO
k
10
R1

R4 
AIN+
AIN-

2
3

R3 

+
10 k

RL

RL
RL

SENSEEXC-

5RSHUNT-

10

RSHUNT+

1

10 kO
R2

ADC
24-bitPrecision
Instrumentation Amp

789

100 k
100kO

TEDS
SER

RJ50

Figure 25: Connecting a Half-Bridge Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

52

Wiring Signals

Shunt Calibration in Half-Bridge Poisson Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 102 for the equation used forshunt calibration in a Half-Bridge Poisson configuration.
To perform shunt calibration in a Half-Bridge Poisson configuration using the internal 100 k
resistor, connect the internal RSHUNT+ and RSHUNT– lines across gage Ror R,as shown in
Figure 24 and Figure 25. You can then use software to switch in 100 k across the selected
gage when no strain is applied to the specimen, creating a known change in the bridge output.
Using software, you can then measure the output of the bridge, compare it to the expected
bridge output value, and adjust the gain of the DT9838 to compensate for these errors.
Once you have performed the shunt calibration procedure, you can disconnect the RSHUNT+and RSHUNT– lines, if desired.
Refer to your software documentation for more information about shunt calibration.

53

Chapter 3

Wiring a Half-Bridge Bending Circuit
The Half-Bridge Bending configuration, shown in Figure 26, measures bending strain, rejects
axial strain, and compensates for temperature.

R4 (+)StrainGage

R3 (–)Bending

Figure 26: Half-Bridge Bending Configuration

The Half-Bridge Bending configuration has the following characteristics:• Uses two active strain gage elements.
• One strain gage element, R4 (+, is mounted in the direction of bending strain on the topof the specimen.
The other strain gage element, R3 (–is mounted in the direction of bending strain on thebottom of the specimen.
• The DT9838 provides two internal 10 k resistors (R1 and R2) to complete the sensor sideof the bridge circuit.
Figure 27 shows how to connect a Half-Bridge Bending circuit to the DT9838 when using thegeneral-purpose STP STRAIN accessory and remote sensing.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

54

Wiring Signals

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC+

6

SENSE+

4

BridgeExcitation
10 kΩ
k
10
R1

R4
AIN+
AIN-

2
3

R3 

RL
RL

SENSE-5

EXCRSHUNT-

7
10

RSHUNT+

1
8
9

+
10kΩ
k
10
R2

-

ADC
24-bitPrecision
Instrumentation Amp

100 k
100 kΩ

TEDS
SER

RJ50

Figure 27: Connecting a Half-Bridge Bending Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

Remote Sensing In Half-Bridge Bending Configurations
Although not required for operation in Half-Bridge Bending configurations, it isrecommended that you connect the bridge SENSE+ and SENSE– lines, as shown in Figure 27
to minimize voltage drops caused by the lead wire resistance of the EXC+ and EXC– lines.
This is most important in applications where long wires and/or small gauge wires, whichhave greater resistance, are used.
If you do not use remote sense lines, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 28, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.

55

Chapter 3

RL

EXC+
SENSE+

General-Purpose STP STRAIN
Accessory Connected to DT9838
6
4

BridgeExcitation
10kΩ
k
10
R1

R 4 
AIN+
AIN-

2
3

R 3 RL

RL
RL

SENSEEXC-

5RSHUNT-

10

RSHUNT+

1

+
10 kΩ
k
10
R2

ADC
24-bitPrecision
Instrumentation Amp

7

8
9

100kΩ
k
100

TEDS
SER

RJ50

Figure 28: Connecting a Half-Bridge Bending Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

Shunt Calibration in Half-Bridge Bending Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 102 for the equation used forshunt calibration in a Half-Bridge Bending configuration.
To perform shunt calibration in a Half-Bridge Bending configuration using the internal 100 k
resistor, connect the internal RSHUNT+ and RSHUNT– lines across gage Ror R,as shown in
Figure 27 and Figure 28. You can then use software to switch in 100 k across the selected
gage when no strain is applied to the specimen, creating a known change in the bridge output.
Using software, you can then measure the output of the bridge, compare it to the expected
bridge output value, and adjust the gain of the DT9838 to compensate for these errors.
Once you have performed the shunt calibration procedure, you can disconnect the RSHUNT+and RSHUNT– lines, if desired.
Refer to your software documentation for more information about shunt calibration.

56

Wiring Signals

Connecting Full-Bridge Circuits
The DT9838 module supports the following full-bridge configurations:• Full-Bridge Bending• Full-Bridge Bending Poisson• Full-Bridge Axial Poisson
This section describes how to wire the Full-Bridge Bending, Full-Bridge Bending Poisson, andFull-Bridge Bending configurations to the DT9838 module. The wiring diagram is the same for
all full-bridge configurations; however, the meaning of R, R, R, and R differs depending on
the configuration you choose. For more information about these bridge configuration types,
refer to page 98.

Wiring a Full-Bridge Bending Circuit
The Full-Bridge Bending configuration, shown in Figure 29, measures bending strain. It also
rejects axial strain, compensates for temperature, and compensates for lead resistance if
remote sense lines are used.

R2 (+)StrainGage

R1 (–)StrainGage
R4 (+)R3 (–)Bending

Figure 29: Full-Bridge Bending Configuration

57

Chapter 3
The Full-Bridge Bending configuration has the following characteristics:• Uses four active strain gages.
• Two strain gages, R4 (+) and R2 (+are mounted in the direction of bending strain on
the top of the specimen.
The other two strain gages, R3 (–) and R1 (–), are mounted in the direction of bendingstrain on the bottom of the specimen.
Figure 30 shows how to connect a Full-Bridge Bending circuit to the DT9838 when using thegeneral-purpose STP STRAIN accessory and remote sensing.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC +SENSE+

64k
1010kΩ

R4

R1





AIN+
AIN-

- V +
O

2
3


R2



BridgeExcitation

10kΩ
k
10

R3

RL
RL

SENSE EXC -57

RSHUNT-

10

RSHUNT+

1
8
9

+
-

ADC
24-bitPrecision
Instrumentation Amp

100 k
100 kΩ

TEDS
SER

RJ50

Figure 30: Connecting a Full-Bridge Bending Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

58

Wiring Signals

Remote Sensing in Full-Bridge Bending Configurations
Although not required for operation, it is recommended that you connect the bridge SENSE+
and SENSE– leads, as shown in Figure 30 to minimize voltage drops caused by the lead wire
resistance (RL) of the EXC+ and EXC– lines. This is most important in applications where longwires and/or small gauge wires, which have greater resistance, are used.
If you do not use remote sense leads, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 31, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.

RL

EXC +

6

SENSE+

4





AIN+
AIN-

- V +
O
R3

BridgeExcitation
1010
kΩk

R4

R1

R2

General-Purpose STP STRAIN
Accessory Connected to DT9838

2
3





SENSE EXC -5

RL

RSHUNT-

10

RL

RSHUNT+

1

RL

+
10kΩ
k
10

ADC
24-bitPrecision
Instrumentation Amp

789

100 k
100kΩ

TEDS
SER

RJ50

Figure 31: Connecting a Full-Bridge Bending Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

Shunt Calibration in Full-Bridge Bending Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 103 for the equation used forshunt calibration in a Full-Bridge Bending configuration.
To perform shunt calibration in a full-bridge configuration using the internal 100 k resistor,
connect the RSHUNT+ and RSHUNT– lines across any active gage (R, R,R,or R),as shownin Figure 30 and Figure 31. You can then use software to switch 100 k across the selected
gage when no strain is applied to the specimen, creating a known change in the bridge output.

59

Chapter 3
Using software, you can then measure the output of the bridge, compare it to the expected
bridge output value, and adjust the gain of the DT9838 to compensate for these errors.
Once you have performed the shunt calibration procedure, you can disconnect the RSHUNT+and RSHUNT– lines, if desired.
Refer to your software documentation for more information about shunt calibration.

Wiring a Full-Bridge Bending Poisson Configuration
The Full-Bridge Bending Poisson configuration, shown in Figure 32, measures bending strain.
It also rejects axial strain, compensates for temperature, compensates for lead resistance, andcompensates for the aggregate effect on the principle strain measurement due to the Poisson’s
ratio of the specimen material.

R4 (+)StrainGage

R1 (–)StrainGage

R3 (–)R2 (+)Bending

Figure 32: Full-Bridge Bending Poisson Configuration

The Full-Bridge Bending Poisson configuration has the following characteristics:• Uses four active strain gages.
• Two strain gages, R4 (+) and R3 (–), are mounted in the direction of bending strain, with
one mounted on the top and the other on the bottom of the specimen.
The other two strain gages, R2 (+and R1 (–), measure the Poisson effect and aremounted transversely (perpendicular) to the axis of bending strain, with one mounted on
the top and the other on the bottom of the specimen.
Figure 30 shows how to connect a Full-Bridge Bending Poisson circuit to the DT9838 whenusing the general-purpose STP STRAIN accessory and remote sensing.

60Wiring Signals

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC +SENSE+

64k
1010kΩ

R4

R1





- V +
O
R3

R2

BridgeExcitation

AIN+
AIN-

2
3



+
10kΩ
k
10



RL
RL

SENSE EXC -57

RSHUNT-

10

RSHUNT+1
8
9ADC
24-bitPrecision
Instrumentation Amp

100 k
100 kΩ

TEDS
SER

RJ50

Figure 33: Connecting a Full-Bridge Bending Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

Remote Sensing in Full-Bridge Bending Poisson Configurations
Although not required for operation, it is recommended that you connect the bridge SENSE+
and SENSE– leads, as shown in Figure 33, to minimize voltage drops caused by the lead wire
resistance (RL) of the EXC+ and EXC– lines. This is most important in applications where longwires and/or small gauge wires, which have greater resistance, are used.
If you do not use remote sense leads, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 34, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.

61

Chapter 3

RL

R4

R1





EXC +

6

SENSE+

4


AIN+
AIN-

R3

BridgeExcitation
10 k
10 kΩ

- V +
O
R2

General-Purpose STP STRAIN
Accessory Connected to DT9838

2
3


SENSE EXC -5

RL

RSHUNT-

10

RL

RSHUNT+

1

RL

+
10 k
10 kΩ

ADC
24-bitPrecision
Instrumentation Amp

789

100 k
100kΩ

TEDS
SER

RJ50

Figure 34: Connecting a Full-Bridge Bending Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

Shunt Calibration in Full-Bridge Bending Poisson Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 103 for the equation used forshunt calibration in a Full-Bridge Bending Poisson configuration.
To perform shunt calibration in a full-bridge configuration using the internal 100 k resistor,
connect the RSHUNT+ and RSHUNT– lines across any active gage (R, R,R,or R), as
shown in Figure 33 and Figure 34. You can then use software to switch 100 k across theselected gage when no strain is applied to the specimen, creating a known change in thebridge output. Using software, you can then measure the output of the bridge, compare it to
the expected bridge output value, and adjust the gain of the DT9838 to compensate for theseerrors.
Once you have performed the shunt calibration procedure, you can disconnect the RSHUNT+and RSHUNT– lines, if desired.
Refer to your software documentation for more information about shunt calibration.

62

Wiring Signals

Wiring a Full-Bridge Axial Poisson Circuit
The Full-Bridge Axial Poisson configuration, shown in Figure 35, measures axial strain. It also
compensates for temperature, rejects bending strain, compensates for lead resistance if remotesense lines are used, and compensates for the aggregate effect on the principle strain
measurement due to the Poisson ratio of the specimen material.

R2 (+)StrainGage

R1 (–)StrainGage

R4 (+)R3 (–)Axial

Figure 35: Full-Bridge Type Axial Poisson Configuration

The Full-Bridge Axial Poisson configuration has the following characteristics:• Uses four active strain gages.
• Two strain gages, R4 (+and R2 (+), are mounted in the direction of axial strain, with one
mounted on the top and the other on the bottom of the specimen.
The other two strain gages, R3 (–)and R1 (–), measure the Poisson effect and aremounted transversely (perpendicular) to the axis of axial strain, with one mounted on the
top and the other on the bottom of the specimen.
Figure 36 shows how to connect a Full-Bridge Axial Poisson circuit to the DT9838 when using
the general-purpose STP STRAIN accessory and remote sensing.

Note: When remote sensing is used, enter 0  for the lead wire correction coefficient insoftware. Refer to page 100 for more information.

63

Chapter 3

General-Purpose STP STRAIN
Accessory Connected to DT9838
EXC +SENSE+
R4

R1




AIN+
AIN-



R3

BridgeExcitation
1010
kΩk

- V +
O
R2

6
4

2
3



k
1010kΩRL
RL

SENSE EXC -57

RSHUNT-

10

RSHUNT+1
8
9ADC
24-bit+-Precision
Instrumentation Amp

100 k
100 kΩ

TEDS
SER

RJ50

Figure 36: Connecting a Full-Bridge Axial Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

Remote Sensing in Full-Bridge Axial Poisson Configurations
Although not required for operation, it is recommended that you connect the bridge SENSE+
and SENSE– leads, as shown in Figure 36, to minimize voltage drops caused by the lead wire
resistance (RL) of the EXC+ and EXC– lines. This is most important in applications where longwires and/or small gauge wires, which have greater resistance, are used.
If you do not use remote sense leads, you must connect the sense leads to the excitation leads(connect SENSE+ to EXC+ and SENSE– to EXC–), as shown in Figure 37, to ensure proper
bridge voltage regulation. If the lead wire resistance is known, you can enter the lead wire
correction coefficient in software. Refer to page 100 for more information.

64

Wiring Signals

RL

R4

R1





EXC +

6

SENSE+

4


AIN+
AIN-

R3

BridgeExcitation
10 k
10 kΩ

- V +
O
R2

General-Purpose STP STRAIN
Accessory Connected to DT9838

2
3


SENSE EXC -5

RL

RSHUNT-

10

RL

RSHUNT+

1

RL

ADC
24-bit

+
10 k
10 kΩ

Precision
Instrumentation Amp

789

100 k
100kΩ

TEDS
SER

RJ50

Figure 37: Connecting a Full-Bridge Axial Poisson Circuit to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory Without Remote Sensing

Shunt Calibration in Full-Bridge Axial Poisson Configurations
When setting up your strain gage, you can use shunt calibration to correct for errors due tolead wire resistance (RL) in the excitation wiring. Refer to page 103 for the equation used forshunt calibration in a Full-Bridge Axial Poisson configuration.
To perform shunt calibration in a Full-Bridge Axial Poisson configuration using the internal
100 k resistor, connect the RSHUNT+ and RSHUNT– lines across any active gage (R, R,R,
or R),as shown in Figure 36 and Figure 37. You can then use software to switch 100 k acrossthe selected gage when no strain is applied to the specimen, creating a known change in thebridge output. Using software, you can then measure the output of the bridge, compare it to
the expected bridge output value, and adjust the gain of the DT9838 to compensate for theseerrors.
Once you have performed the shunt calibration procedure, you can disconnect the RSHUNT+and RSHUNT– lines, if desired.
Refer to your software documentation for more information about shunt calibration.

65

Chapter 3

Connecting Load Cells and Other Transducers
The DT9838 supports load cells (force sensors) as well as pressure transducers, and/or torquesensors that are based on the Wheatstone bridge.
These transducers typically use a full-bridge configuration with a 350  nominal bridge
resistance.
Many large load cells use the remote sense wires, as they are located farther away from theDT9838. Smaller load cells, which are located closer to the DT9838 typically, do not use remotesense lines; instead, the excitation (EXC+ and EXC–) and remote sense (SENSE+ and SENSE–)
lines are connected at the DT9838.
Figure 38 shows how to connect load cells and other sensors that use remote sensing to theDT9838 when connected to the general-purpose STP STRAIN accessory. Figure 39 shows how
to connect load cells and other sensors that do not use remote sensing to the DT9838 whenconnected to the general-purpose STP STRAIN accessory.

Notes: In load-cell configurations, the RSHUNT– and RSHUNT+ lines are not used, but
optionally can be connected at the DT9838. TEDS connections are also optional.
Refer to the sensor manufacturer for information on wiring to your sensor type.

General-Purpose STP STRAIN
Accessory Connected to DT9838

Load Cell Sensor
EXC +SENSE+

64k
1010kΩ

R4

R1

AIN+
AIN-

- VO +

2
3

SENSE EXC -57

RSHUNT-

10

RSHUNT+
TEDS

+
10kΩ
k
10

R3

R2

BridgeExcitation

DATA
RTN

Precision
Instrumentation Amp

100 k
100kΩ

1
8
9

ADC
24-bit

TEDS
SER

RJ50

Figure 38: Connecting a Load Cell or Other Transducer to the DT9838 When Using theGeneral-Purpose STP STRAIN Accessory and Remote Sensing

66Wiring Signals

General-Purpose STP STRAIN
Accessory Connected to DT9838

Load Cell Sensor
RL

EXC +

6

SENSE+

4k
1010kΩ

R4

R1

AIN+
AIN-

- VO +

2
3

RL

TEDS

+
k
1010
kΩ

R3

R2

BridgeExcitation

SENSE EXC -5

RSHUNT-

10

RSHUNT+

1

DATA
RTN

8
9

ADC
24-bitPrecision
Instrumentation Amp

7
100kΩ
k
100

TEDS
SER

RJ50

Figure 39: Connecting a Load Cell or Other Transducer to the DT9838
Without Using Remote Sensing

67Chapter 3

Connecting Voltage Inputs
Figure 40 shows how to connect a voltage input source to a channel of the DT9838 when it isconnected to a general-purpose STP STRAIN accessory. Note that the voltage source must bein the ±250 mV full-scale range.

General-Purpose STP STRAIN
Accessory Connected to DT9838

Device Under Test
6
4

BridgeExcitation
10 kO
k
10

Voltage Source +(+/- 250 mV
Full-Scale) R*

AIN+

2

+

AIN-

3

10kO
k
10

ADC
24-bitPrecision
Instrumentation Amp

57
10*To minimize noise pickup,
reference pin 3 to analog
ground with a resistor
between 100 Oand 10 kO.

100kO
k
100

1
8
9

TEDS
SER

Figure 40: Connecting Voltage Inputs to the DT9838 When Using the General-Purpose
STP STRAIN Accessory

Note: For best accuracy when connecting voltage inputs, use twisted-pair wires.

68

Wiring Signals

Connecting a Tachometer Input Signal
You can connect a ±30 V tachometer input signal to External Trigger and Tachometer
connector (J6) on the DT9838 module, as shown in Figure 41.

Note: In software, you can read tachometer measurements as part of the analog input
channel list. Refer to page 110 for more information on tachometer measurements.

Ext Trigger andTachometer
Connector

Tachometer In - Pin 1

Tachometer Return - Pin 2

SignalSourceFigure 41: Connecting a Tachometer Input Signal to the DT9838 Module

69

Chapter 3

Connecting an External Trigger Signal
You can connect an external digital trigger signal to the External Trigger and Tachometer
connector (J6) on the DT9838 module, as shown in Figure 42. Refer to page 110 for more
information on the external digital trigger.

Ext Trigger andTachometer
Connector

External Trigger Return - Pin 4

External Trigger - Pin 3

Trigger
SourceFigure 42: Connecting an External Trigger Input Signal to the DT9838 Module70

4
Verifying the Operation of a Module
Select the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Measure Strain Gage Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

71

Chapter 4

Set Up and Install the Module(see Chapter 2 starting on page 25)
Wire Signals(see Chapter 3 starting on page 35)

Verify the Operation of the Module(this chapter)

You can verify the operation of a DT9838 module using the QuickDAQ application.
QuickDAQ allows you to acquire and analyze data from all Data Translation USB and
Ethernet devices, except the DT9841 Series, DT9817, DT9835, and DT9853/54. This chapter
describes how to verify the operation of a DT9838 module using the QuickDAQ base version.

72

Verifying the Operation of a Module

Select the Device
To get started with your DT9838 module and QuickDAQ, follow these steps:
1. Connect the DT9838 module to the USB port of your computer, and connect your strain
gage sensors to the module.
2. Start the QuickDAQ application.
The Device Selection window appears.

3. For the Device Family selection, select OpenLayersDevices.
By default, the application "discovers" all devices that are available for the specified
device family and displays the module name for the USB devices in the drop-down list. If
you want to refresh this list to determine if other devices are available, click Refresh.
4. Select the module name for the DT9838 module that you want to use from the list of
Available Devices, and click Add.
Information about the device, including the model number, serial number, firmware version, driver
version, and scanning status is displayed.

73

Chapter 4

5. If you want to rename your device, do the following:a. Click the Row Selector button for the device.
b. Click the IP address or module name in the Name column to highlight it and enter ameaningful name to represent each available device.
6. If you are using multiple devices, you must configure one device as the clock and trigger
master, as follows:a. Click the Row Selector button for the device that you want to be the clock and trigger
master.
b. For the clock and trigger master device, check the box under the Master column.

Note: Only one device can be the clock and trigger master. If you are using a single
device, the application automatically configures the device as the master.
The DT9838 devices support that capability of synchronizing up to four devices. If you areusing more than one of these devices, ensure that you connect the devices together using
network cables and the Synchronization (RJ45) connector on each device. Then, configure
one device as the master and the other devices as slaves. The software automaticallydrives out the appropriate clock and trigger signals. Refer to page 112 for more
information on syncrhonizing devices.

7. (Optional) If you want to remove a device from list of selected devices, click the Row
Selector button for the device, and then click Remove.
8. Once you have added all the devices that you want to use with the application, click OK.
The latest state is saved and used when the application is next run, and the interface of the
QuickDAQ is displayed.

74

Verifying the Operation of a Module

75

Chapter 4

Measure Strain Gage Data
The following steps describe how to use the QuickDAQ application to configure a strain gage
measurement.
This example uses a full-bridge strain gage (full-bridge bending configuration) connected to a
DT9838 module to measure strain.

Configure the Channels
Configure the channels as follows:
1. Ensure that the strain gage is connected to your data acquisition device.
In this example, the strain gage is connected to analog input channel 0 of the DT9838. Refer toFigure 30 on page 58 for the wiring diagram used for a full-bridge bending configuration.
2. Configure each analog input channel by clicking the Input Channel Configuration
toolbar button () or by clicking the Configuration menu and clicking Input
Channel Configuration.
3. Enable analog input channel 0 by clicking the Enable checkbox for analog input channel
0.

4. In the Channel Name column, enter Full Bridge Bending for the name of analog input
channel 0.
5. In the Enable Shunt Resistor column, leave the checkbox unchecked; this disables theshunt resistor.
6. Click the Configure and Calibrate button.
The following wizard appears:

76Verifying the Operation of a Module

7. Select Strain Gage, and click Next. (Note that TEDS is not supported for this sensor;
therefore, you do not need to click the Open TEDS data file... button.)
A screen similar to the following appears:

77Chapter 4

8. For the Bridge Type field, select the bridge configuration of your strain gage.
In this example, the Full Bridge Bending bridge configuration is used.
9. For the Excitation Voltage field, enter the excitation voltage value for your strain gage.
In this example, 5 V is used as the excitation voltage value.
10. For the Nominal Gage field, enter the nominal gage resistance, in ohms, for your strain
gage as determined by the manufacturer.
In this example, 350 is used as the nominal gage resistance.
11. For the Gage Factor field, enter the gage factor for your strain gage as determined by the
manufacturer.
In this example, 2 is used as the gage factor.
12. For the Using Sense Lines field, select Yes if you are using remote sense lines in yourwiring, or No if you are not using remote sensing in your wiring.
In this example, remote sensing is not used.
13. For the Lead Wire Resistance field, enter the lead wire resistance, in ohms, for your strain
gage.
In this example, 0.1 is used as the lead wire resistance.
14. For the Min Range field, enter the minimum value of the range for your strain gage.
In this example, –1000 is used as the minimum strain value.

78

Verifying the Operation of a Module
15. For the Max Range field, enter the maximum value of the range for your strain gage.
In this example, 1000 is used as the maximum strain value.
16. For the Units field, select the engineering units for the strain gage.
In this example, Strain is used.
17. In the Poisson Ratio column, enter the Poisson ratio for your strain gage.
In this example, the Poisson ratio is not used.
18. Click Next.
A screen similar to the following appears:

19. Select the calibration steps to perform.
In this example, Offset Nulling and Shunt Calibration are selected.
20. Click Next.
A screen similar to the following appears:

79Chapter 4

21. Ensure that the bride is in the unstrained state, and the click the Calibrate button to
perform offset nulling procedure.
The expected voltage is shown along with the calibrated offset voltage.

80

Verifying the Operation of a Module

22. Click Next.
A screen similar to the following appears:

81Chapter 4

23. For the Select Resistor Source field, select Internal if you are using the internal shunt
resistor provided on the DT9838 module to perform shunt calibration, or External if you
are using your own external resistor to perform shunt calibration.
In this example, Internal is used.
24. For the Select Node to Shunt field, select the resistive node or element to which to apply
the shunt resistor.
In this example, R2 is used.
25. Click Calibrate to perform the shunt calibration procedure.
The calculated value is displayed along with the measured value and correction coefficient.

82

Verifying the Operation of a Module

26. Click Finish.
27. If desired, enter a test point number under the Point # column.
In this example, 1 is used.
28. Click Close to close the Configure Devices dialog box.

83

Chapter 4

Configure the Recording Settings
For this example, configure the recording settings as follows:
1. Click the Recording tab of the Acquisition Config window.

2. For Filename generation, use the default Filename option.
3. For Filename, use the default name for the data file.
4. Leave the Enable Continuous Acquisition checkbox unchecked.

84

Verifying the Operation of a Module
5. For Acquisition Duration, enter 5 seconds.
The number of seconds for the total run and the amount of available disk space are shown.
6. For X Span Axis, enter 5 seconds.

Configure the Acquisition Settings
For this example, configure the acquisition settings as follows:
1. Click the Acquisition tab of the Acquisition Config window.

85

Chapter 4
2. For the Per Channel Sampling Frequency text box, enter 1000.
The sampling rate, sample interval, and number of scans are displayed.
3. For the Trigger Source check box, select Software to ensure that the measurement starts
as soon as the Record button is clicked.

Start the Operation
Once you have configured the channels, start acquisition and log data to disk by clicking theRecord toolbar button ().
Results similar to the following are displayed in the Channel Plot window.

Note: Many additional options are provided in QuickDAQ for measuring and analyzing thedata. Refer to the QuickDAQ User’s Manual for detailed information.

86

Part 2: Using Your Module5
Principles of Operation
Analog Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Tachometer Input Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Synchronizing Acquisition on Multiple Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

89

Chapter 5
Figure 43 shows a block diagram of the DT9838 module.

Trigger
In/Out

Tach

Tach

Sync
Sync
In/Out
Sync
Ref
Clock
In/OutTrigger
Trigger

4 pos
Screw
Terminal

EXC +SENSE+

BridgeInput 0ADC
PCG

BridgeExcitation

ID/CALEEPROM

LVDS

LVDS

SyncBus

LVDS

RJ45

SRAM
128KB

10kO

+

ADC
24-bit10kO

SENSE EXC -Precision
Instrumentation
Amp

Tach

Clocks&Triggers

PLL _REF_CLK

32-bitAIN+
AIN-

RSHUNT-

Acquisition Ctrl

TEDS
SER

DATA
RTN
RJ50

BridgeInput 1ADC
24 bitBridgeInput 2ADC
24 bitBridgeInput 3ADC
24 bitInput
FIFO
8 ksamples
Bus Interface&
Control Registers

TEDS

USB 2.0
High-Speed
Interface

100kO

RSHUNT+DAC
16-bitFigure 43: Block Diagram of the DT9838 Module

90

USB

Principles of Operation

Analog Input Features
This section describes the following features of the analog input (A/D) subsystem on theDT9838 module:• Analog input channels, described on this page
• Bridge configurations, described on page 92• Transducer support, described on page 99• Bridge excitation, described on page 100• Remote sensing and lead wire correction, described on page 100• Shunt calibration, described on page 101• TEDS, described on page 103• Input resolution, described on page 104• Input ranges and gains, described on page 104• Sample clock sources, described on page 104• Conversion modes, described on page 105• Triggers, described on page 107• Data format, described on page 109• Error conditions, described on page 109

Analog Input Channels
The DT9838 module supports four, simultaneous, analog input channels that accept bridge
sensors through RJ50 connectors on the module.
You can acquire data from a single analog input channel or from a group of analog input
channels on the module. Analog input channels are numbered 0 to 3.
The following subsections describe how to specify the channels.

Specifying a Single Analog Input Channel
The simplest way to acquire data from a single analog input channel is to specify the channel
for a single-value analog input operation using software; refer to page 105 for more
information about single-value operations.

Specifying One or More Analog Input Channels
You can read data from one or more analog input channels by specifying the channel (0 to 3)
in the analog input channel list.

91Chapter 5
The DT9838 module also allows you to read the value of the tachometer input in the analog
input data stream. This feature is particularly useful when you want to correlate the analog
input measurements with tachometer data. Refer to page 110 for more information about thetachometer input channel.
Using software, specify the channels that you want to sample. For the DT9838, you can enter
up to five entries in the analog channel list, including the analog input channels (0 to 3) andthe tachometer input (channel 4).
Because this module features simultaneous sampling, the order of the channels in the channel
list does not matter. You cannot specify the same channel more than once in the list.

Bridge Configurations
All strain gage configurations are based on the concept of a Wheatstone bridge. A Wheatstonebridge is a network of four resistive legs, or nodes. One or more of these nodes can be active
sensing element. Figure 44 shows a basic circuit diagram of a Wheatstone bridge.

VEX+

R1

R4

–

R2

VO

+

R3

Figure 44: Wheatstone Bridge Circuit Diagram

The Wheatstone bridge is the electrical equivalent of two parallel voltage divider circuits. R1and R2 comprise one voltage divider circuit, and R4 and R3 comprise the second voltage
divider circuit. The output of a Wheatstone bridge is measured between the middle nodes of
the two voltage dividers (VO).
Physical phenomena, such as a change in strain applied to a specimen or a temperature shift,changes the resistance of the active sensing elements in the Wheatstone bridge. The
Wheatstone bridge configuration is used to help measure the small variations in resistancethat the sensing elements produce corresponding to a physical change in the specimen.

92

Principles of Operation
A strain gage is a collection of all the active elements of a Wheatstone bridge. You use
different bridge configurations for different tasks. For each analog input channel, the DT9838
module supports the following bridge configurations to measure axial and/or bending strain:• Quarter-Bridge• Quarter-Bridge Temp Comp• Half-Bridge Poisson• Half-Bridge Bending• Full-Bridge Bending• Full-Bridge Bending Poisson• Full-Bridge Axial Poisson

Note: If you do not wish to use a bridge, you can also configure the channel for a voltage
measurement.

You specify the bridge configuration in software. The bridge configuration that you selectdetermines the way you wire the sensor elements to the channel. Refer to Chapter 3 startingon page 35 for more information on how to wire these bridge configurations to the DT9838
module.
Measured strain is determined by referencing the acquired data when the bridge is in thestrained condition to the acquired data when the bridge in an unstrained condition. The
difference in measurements is then applied to the appropriate strain transfer function for theparticular bridge configuration, which yields a value of strain in units of strain or microstrain.
This transfer function can be modified by including corrections for lead wire resistance
and/or shunt calibration.
The following sections provide the circuit diagram for each of the supported bridge
configurations as well as the bridge transfer function that the DT9838 uses to convert voltage
to strain for each configuration. The following terms are used in this section:•  is the measured strain (+e is the tensile strain and – is the compressive strain).
• GF is the gage factor, which is specified by the gage manufacturer. You specify this value
in software for each bridge (analog input channel).
• Rg is the nominal gage resistance, which is specified by the gage manufacturer. You
specify this value in software for each bridge (analog input channel).
• RL is the lead wire resistance. You specify this value in software for each bridge (analog
input channel).
• is the Poisson ratio, defined as the negative ratio of transverse strain to axial(longitudinal) strain. You specify this value in software for each bridge (analog input
channel).
• VEX is the excitation voltage. You specify this value in software. Refer to page 100 for
more information on the excitation voltage.
• Vu is the initial, unstrained voltage output.

93Chapter 5• Vs is the measured voltage output when strained.
• Vr is the voltage ratio that is used in the voltage-to-strain conversion equations and isdefined by the following equation:– VuV r = Vs-----------------V EX
Quarter-Bridge Configuration
Figure 45 shows the circuit diagram that the DT9838 uses for a 3-wire Quarter-Bridge
configuration.

Note: This configuration is used with rectangular and delta rosettes. Tee rosettes are notsupported. Refer to page 42 for more information on rosettes.

RL
In this diagram:
R1

VEX

–

+
–

VO

RL

+

R4 (Rg= )

R1 and R2 are half-bridge completion resistors
that are provided by the DT9838.
R3 is the quarter-bridge completion resistor
that you must supply.

RL

R2
R3
User-supplied

R4 is the active strain-gage element thatmeasures the tensile strain (Rg = +).

Figure 45: Quarter-Bridge Circuit Diagram

For a 3-wire Quarter-Bridge configuration, the following bridge transfer function is used toconvert voltage to strain when lead wire correction and shunt calibration are not used:– 4V rStrain    = ------------------------------GF  1 + 2V r 
Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 42 for information on wiring a Quarter-Bridge configuration to the DT9838.

94Principles of Operation

Quarter-Bridge Temp Comp Configuration
Figure 46 shows the circuit diagram that the DT9838 uses for the Quarter-Bridge Temp Compconfiguration. This circuit diagram (and bridge transfer function) is also used for a
Quarter-Bridge configuration where the user places a resistor at the strain gage.

RL
R1

VEX

R4 (Rg = )
–

+
–
R2

In this diagram:

VO

+

RL

RL

R1 and R2 are half-bridge completion resistors
that are provided by the DT9838.
R4 is an active strain-gage element thatmeasures axial or bending strain in theprincipal direction of strain (Rg = +).

R3 (Rg = dummy)

R3 is a dummy strain gage element (Rg =dummy gage) that has the same nominal
resistance and temperature coefficient as R4.

Figure 46: Quarter-Bridge Temp Comp Circuit Diagram

For the Quarter-Bridge Temp Comp configuration, the following bridge transfer function isused to convert voltage to strain when lead wire correction and shunt calibration are not used:– 4V rStrain    = ------------------------------GF  1 + 2V r 
Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 47 for information on wiring a Quarter-Bridge Temp Comp configuration to theDT9838.

Half-Bridge Poisson Configuration
Figure 47 shows the circuit diagram that the DT9838 uses for the Half-Bridge Poisson
configuration.

95

Chapter 5

RL

In this diagram:

R1

VEX

R4 (Rg = )
–

+
–

VO

RL

+

R3 (Rg= –RLR2

R1 and R2 are half-bridge completion resistors thatare provided by the DT9838.
R4 is the active strain-gage element that measures
strain in the direction of axial or bending strain(Rg = +).
R3 is the active strain gage that measures strain in the
direction perpendicular to the principal axis of strain(Rg = –).

Figure 47: Half-Bridge Poisson Circuit Diagram

For the Half-Bridge Poisson configuration, the following bridge transfer function is used toconvert voltage to strain when lead wire correction and shunt calibration are not used:– 4V rStrain    = -----------------------------------------------------------GF   1 +   – 2V r   – 1  Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 50 for information on wiring a Half-Bridge Poisson configuration to the DT9838.

Half-Bridge Bending Configuration
Figure 48 shows the circuit diagram that the DT9838 uses for the Half-Bridge Bending
configuration.

RL
In this diagram:
R1

VEX

R4 (Rg = )
–

+
–
R2

VO

+

RL

RL

R3 (Rg = –R1 and R2 are half-bridge completion resistors
that are provided by the DT9838.
R3 (Rg = –) and R4 (Rg = +) are both active
strain gages mounted in the direction ofbending strain but on opposite sides of thespecimen.

Figure 48: Half-Bridge Bending Circuit Diagram96

Principles of Operation
For the Half-Bridge Bending configuration, the following bridge transfer function is used toconvert voltage to strain when lead wire correction and shunt calibration are not used:

2V-r
Strain    = –----------GF
Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 54 for information on wiring a Half-Bridge Bending configuration to theDT9838.

Full-Bridge Bending Circuit
Figure 49 shows the circuit diagram that the DT9838 uses for the Full-Bridge Bending
configuration.

RL

R4 (+)R1 (–)In this diagram:
Four active strain gage elements are used.

VEX

–

+
–

R1 (–) and R3 ( –) are mounted in the direction ofbending strain on the bottom of the specimen.

+VO

R2 (+) and R4 (+) are mounted in the direction ofbending strain on the top of the specimen.
R2 (+)R3 (–)RL

Figure 49: Full-Bridge Bending Circuit Diagram

For the Full-Bridge Bending configuration, the following bridge transfer function is used toconvert voltage to strain when lead wire correction and shunt calibration are not used:

Vr
Strain    = –-------GF
Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 57 for information on wiring a Full-Bridge Bending configuration to the DT9838.

97Chapter 5

Full-Bridge Bending Poisson Configuration
Figure 50 shows the circuit diagram that the DT9838 uses for the Full-Bridge Bending Poisson
configuration.

RL
In this diagram:
R4 (+)R1 (–

VEX

–

+
–

R2 (+)VO

Four active strain gage elements are used.
R3 (–) and R4 (+) are mounted in the direction ofbending strain with R4 mounted on the top of thespecimen and R3 mounted on the bottom of thespecimen.

+

R3 (–)R1 (–) and R2 (+) act together as a Poisson
gage and are mounted perpendicular to theprincipal axis of strain with R1 mounted on the
top of the specimen and R2 mounted on thebottom of the specimen.

RL

Figure 50: Full-Bridge Bending Poisson Circuit Diagram

For the Full-Bridge Bending Poisson configuration, the following bridge transfer function isused to convert voltage to strain when lead wire correction and shunt calibration are not used:– 2V r Strain    = ------------------------GF  1 +  
Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 60 for information on wiring a Full-Bridge Bending Poisson configuration to theDT9838.

98

Principles of Operation

Full-Bridge Axial Poisson Configuration
Figure 51 shows the circuit diagram that the DT9838 uses for the Full-Bridge Axial Poisson
configuration.

RL
In this diagram:
R4 (+)R1 (–

VEX

–

+
–

VO

Four active strain gage elements are used.
R2 (+) and R4 (+) are mounted in the direction of axial
strain with R2 mounted on the top of the specimen andR4 mounted on the bottom of the specimen.

+

R1 (–) and R3 (–) act together as a Poisson gage
and are mounted perpendicular to the principal axis ofstrain with R1 mounted on the top of the specimen andR3 mounted on the bottom of the specimen.
R3 (–)R2 (+)RL

Figure 51: Full-Bridge Axial Poisson Circuit Diagram

For the Full-Bridge Axial Poisson configuration, the following bridge transfer function is used
to convert voltage to strain when lead wire correction and shunt calibration are not used:– 2V rStrain    = -------------------------------------------------------GF    + 1  – V r   – 1  Refer to page 100 for more information on lead wire resistance; refer to page 101 for more
information on shunt calibration.
Refer to page 63 for information on wiring a Full-Bridge Axial Poisson configuration to theDT9838.

Transducer Support
In addition to strain gages, the DT9838 supports a variety of transducer types, including loadcells, pressure transducers, and torque sensors that are based on the Wheatstone bridge.
A load cell, which consists of a number of strain gages, measures load and force bydetermining the deformation of a structural member as a load or force is applied. Pressuretransducers, which consist of strain gages mounted on a diaphragm, measure the deformationof the diaphragm that is proportional to the pressure that is applied. Torque sensors, which
consist of strain gages mounted on a torsion bar, measure the shear stress as the torsion bar
turns that is proportional to the torque.

99

Chapter 5
To use these transducers, configure the analog input channel for a full-bridge configuration.
These transducers typically use 350  nominal bridge resistance. Refer to page 66 for wiring
information.
Instead of supplying a gage factor, use software to enter the sensitivity of the unit provided by
the manufacturer of the transducer. For example, a load cell rated for 100 pounds with a
2 mV/V output has a full-scale output of 20 mV when using 10 V of excitation.
Some transducers also support TEDS or virtual TEDS. The DT9838 provides TEDS support tointerface to these transducers directly. Refer to page 103 for more information on TEDS.

Bridge Excitation
Using software, you can program the analog input subsystem on the DT9838 to accept aninternal bridge excitation source between 0 VDC and 10 VDC, with better than 1 mV ofresolution. The internal bridge excitation circuitry consists of a 16-bit DAC that programs thebridge excitation for all four channels, and a separate bridge drive and sense amplifier foreach channel for individual channel regulation. Each channel is also individually current
limited to 50 mA.
The DT9838 can be operated on USB power alone; however, you may not be able to use all thechannels depending on the bridge resistance and excitation voltage. Alternatively, you canpowered the DT9838 using an external 5 VDC to 24 VDC power supply. Refer to is shown in
Table 1 on page 29 for detailed information on the number of channels supported with USB
power or external power using various bridge and excitation voltage configurations.

Remote Sensing and Lead Wire Correction
All bridge types, with the exception of the 3-wire Quarter-Bridge configuration, support theuse of remote sense lines (SENSE+ and SENSE–). Refer to Chapter 3 starting on page 35 forconnection information. The remote sense lines continuously monitor the voltage that is
applied across the bridge at the bridge connection points and null the effects of lead wire
resistance by regulating the excitation voltage across a remotely located bridge or half bridge.
If you do not use the remote sense lines to regulate the bridge, the sense lines must still beconnected to the excitation lines either at the screw terminal panel or as the lines exit the RJ50
connector (connect SENSE+ to EXC+ and SENSE– to EXC–). You then have the option tocorrect for lead wire effects in software by entering the value of the lead wire resistance fromthe DT9838 module to the strain gage. Use the same gage wire for the EXC+ and EXC– lines toensure that the resistances are matched. Using software, enter the resistance of one line, notthe sum of the two lines. The software applies the correction coefficient to the bridge transfer
function for the particular channel.

Note: If the remote sense leads are used, enter a lead wire resistance correction value of 0 .
The module cannot detect whether the remote sense lines have been connected or not, so you
must be aware of how the strain gage was wired and determine the appropriate lead wire
correction value.

100Principles of Operation
The bridge transfer functions that are used to convert voltage to strain when lead wire
correction is used are as follows:• Quarter-Bridge and Quarter-Bridge Temp Comp:– 4V rR L-Strain    = -------------------------------  1 + ----
GF  1 + 2V r 
R g• Half-Bridge Poisson:– 4V rStrain    = ------------------------------------------------------------  1 + R-----L-
GF   1 +   – 2V r   – 1  
R g
• Half-Bridge Bending:– 2V rRL
Strain    = ------------  1 + ------
GF
Rg• Full-Bridge Bending:

–V r
2R L
Strain    = --------  1 + ---------
GF
Rg• Full-Bridge Bending Poisson:– 2V r2R
Strain    = --------------------------  1 + --------L-GF  1 +   Rg • Full-Bridge Axial Poisson:– 2V r2R L
Strain    = ---------------------------------------------------------  1 + ---------
GF    + 1  – V r   – 1  
RgShunt Calibration
As discussed in Chapter 3 starting on page 35, shunt calibration is another method ofcompensating for the lead wire resistance in the bridge. It is used to calibrate a configured
channel to an artificial amount of strain that is simulated by altering the resistance of one
element of the connected bridge.
With the bridge in the unstrained condition, you programmatically shunt one of the elementsof the bridge with a known precision resistor value. You can use either your own external
resistor or the internal 100 kresistor on the DT9838 module. Using software, you can thenread the value of the bridge, compare it to the expected value, and calibrate the channel
accordingly.
The following sections describe the bridge transfer functions that the DT9838 uses for eachbridge configuration to simulate strain during shunt calibration.

101

Chapter 5
Keep the following definitions in mind as you read these sections:• sis a calculated value. It is the expected value of strain with the shunt calibration resistor
engaged.
• RSH is the shunt calibration resistance.
• SHis the measured value of strain with a shunt calibration resistor engaged.
• U is a calculated value. It is the expected value of Vr with a shunt calibration resistor
applied to the bridge.
Note that the sign of U depends on which of the four bridge elements are shunted.
If R1 or R3 is shunted, U is negative and is determined as follows:–R g U = -------------------------4R sh + 2R g
If R2 or R4 is shunted, U is positive and is determined as follows:Rg
U = -------------------------4R sh + 2R g
Shunt Calibration Equation for the Quarter-Bridge and Quarter-Bridge Temp
Comp Configurations
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R3 or R4 of the Quarter-Bridge or Quarter-Bridge Temp Compcircuit:– 4V rRL sStrain    = -------------------------------  1 + ------  -------
GF  1 + 2V r 
Rg SH
Shunt Calibration Equation for the Half-Bridge Poisson Configuration
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R3 or R4 of the Half-Bridge Poisson configuration:– 4V rRL sStrain    = ------------------------------------------------------------  1 + ------  -------
GF   1 +   – 2V r   – 1   
R g   S HShunt Calibration Equation for the Half-Bridge Bending Configuration
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R3 or R4 of the Half-Bridge Bending configuration:– 2V rs
Strain    = ------------  1 + R-----L-  -------
GF R g   S H102

Principles of Operation

Shunt Calibration Equation for the Full-Bridge Bending Configuration
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R1, R2, R3, or R4 of the Full-Bridge Bending configuration:–V r
2R L  s
Strain    = --------  1 + ---------  -------
GF 
R g    S HShunt Calibration Equation for the Full-Bridge Bending Poisson
Configuration
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R1, R2, R3, or R4 of the Full-Bridge Bending Poisson configuration:– 2V r
2R L  s
Strain    = --------------------------  1 + ---------  -------
GF  1 +  
Rg SH
Shunt Calibration Equation for the Full-Bridge Axial Poisson Configuration
The DT9838 uses the following bridge transfer function when lead wire correction and shuntcalibration is used across R1, R2, R3, or R4 of the Full-Bridge Axial Poisson configuration:– 2V rs
2R
Strain    = ---------------------------------------------------------  1 + --------L-  -------
GF    + 1  – V r   – 1   
R g    S HOffset Nulling
A balanced bridge under ideal conditions with zero strain applied produces zero volts. In
practice, the output of a bridge in an unstrained condition is offset from zero slightly due toimperfect matching of bridge resistances.
It is not necessary to balance a bridge prior to the measurement. Instead, you can use software
to make a reference measurement with the bridge in an unstrained condition. All subsequent
data is then offset in software by the reference value.

TEDS
Each analog input channel on the DT9838 module provides a Class II TEDS (Transducer
Electronic Data Sheet) interface through the RJ50 connector. The interface consists of
two-wires (TEDS DATA and TEDS RETURN).
TEDS is supported by some load-cells and other transducers with strain gages. Refer to page
66 for information on wiring TEDS for a load-cell sensor.

103

Chapter 5

Input Resolution
The value that is measured across the bridge of an analog input channel on the DT9838
module is amplified and applied to the 24-bit Sigma-Delta analog-to-digital converter (ADC).
The ADC oversamples the incoming signal, filters the values, and produces a result.
The resolution of the analog input subsystem is fixed at 24 bits.

Input Range
The default full-scale input range for each channel is ±250 mV.

A/D Sample Clock
The DT9838 module supports an internal clock, which is generated by an internal
programmable PLL. Using software, you can program the sample rate from 195.3 Samples/s
to 52.734 kSamples/s.

Note: According to sampling theory (Nyquist Theorem), specify a frequency that is at least
twice as fast as the input’s highest frequency component. For example, to accurately sample a
20 kHz signal, specify a sampling frequency of at least 40 kHz to avoid aliasing.
The modules support a passband from DC to 0.453 x sampling frequency, resulting in a
maximum signal bandwidth of 23.89 kHz.

The actual frequency that the module can achieve may be slightly different than the frequency
you specified due to the accuracy of the clock. You can determine the actual clock frequency
using software.
Internally, the value that you specify for the internal clock frequency is multiplied by 512 to
set the oscillator on the module. For example, if you specify an internal clock frequency of
50 kHz, the module sets the internal oscillator for the A/D converters to 25.6 MHz. The
maximum timebase is 27 MHz.
Once the sample clock is started, the module requires 39 clock pulses before the first A/Dconversion is completed (39/sample rate) due to the group delay of the converters. The
software automatically adjusts for the group delay to provide only valid data in each buffer.
The tachometer data (which does not have the 39 sample group delay) is synchronized withthe analog data stream. This is done through the firmware and device driver by caching thetachometer data and aligning it in time with the analog data in the user’s data buffers.

104Principles of Operation

Analog Input Conversion Modes
The DT9838 module supports the following conversion modes:• Single-value mode, described below• Continuous scan mode, described on page 105

Single-Value Mode
Single value operations are the simplest to use. Using software, you specify the analog input
channel. The module acquires the data from the specified channel and returns the data
immediately. For a single-value operation, you cannot specify a clock source, trigger source,scan mode, or buffer.
Single-value operations stop automatically when finished; you cannot stop a single-value
operation.

Note: You cannot read the value of the tachometer using a standard single-value operation.
To read these values, specify the channel as part of the analog input channel list using
continuous scan mode, described next.

Continuous Scan Mode
Continuous scan mode takes full advantage of the capabilities of the DT9838 module. Usecontinuous scan mode if you want to accurately control the period between successive
simultaneous conversions of all channels in a channel list. You can specify a channel list, clock
source, start trigger, reference trigger, post-trigger scan count, and buffer using software.
You can enter up to five entries in the channel list, including the four analog input channels(A/D channels 0 to 3) and the tachometer (A/D channel 4).
When it detects the start trigger, the module samples all the channels in the list
simultaneously.
If a reference trigger is not specified, data that is acquired after the start trigger is post-trigger
data. The sampled data is placed in the allocated buffer(s). The operation continues until you
stop it or until no more buffers are available.
If a reference trigger is specified, data that is acquired after the start trigger is pre-trigger data;when the reference trigger occurs, pre-trigger data acquisition stops and post-trigger
acquisition starts at the next sample. The sampled data is placed in the allocated buffer(s). The
operation continues until the number of scans that you specify for the post-trigger scan counthave been acquired; at the point, the operation stops. Note that the sample at which the trigger
occurs is not counted as a post-trigger sample. Refer to page 107 for more information about
triggers.

105

Chapter 5
The conversion rate is determined by the frequency of the input sample clock; refer to page104 for more information about the input sample clock. The sample rate, which is the rate at
which a single entry in the channel list is sampled, is the same as the conversion rate due tothe simultaneous nature of the module.
Using software, you can stop a scan by performing either an orderly stop or an abrupt stop. In
an orderly stop, the module finishes acquiring the current buffer, stops all subsequentacquisition, and transfers the acquired data to host memory; any subsequent triggers are
ignored. In an abrupt stop, the module stops acquiring samples immediately; the current
buffer is not completely filled, it is returned to the application only partially filled, and any
subsequent triggers are ignored.
To select continuous scan mode, use software to specify the following parameters:• Specify the data flow as Continuous• Specify the clock source as internal and specify the clock frequency (refer to page 104)
• Specify the start trigger (refer to page 107)
• Specify the reference trigger (refer to page 108)• Specify the post-trigger scan count (the number of post-trigger samples to acquire after
the reference trigger occurs)
Figure 52 illustrates continuous scan mode (using a start and reference trigger) with a channel
list of three entries: channel 0 through channel 2. In this example, pre-trigger analog input
data is acquired when the start trigger is detected. When the reference trigger occurs, thespecified number of post-trigger samples (3, in this example) are acquired.

Trigger Sample is not counted
as post-trigger sample
Post-Trigger Scan Count = 3

Input
SampleClock

Chan 2Chan 2Chan 2Chan 2Chan 2Chan 2Chan 1Chan 1Chan 1Chan 1Chan 1Chan 1Chan 0Chan 0Chan 0Chan 0Chan 0Chan 0Pre-trigger data acquired

Start Trigger occurs

3 Post-trigger samples acquired

Reference Trigger occurs

Figure 52: Continuous Scan Mode106

Principles of Operation

Note: The USB LED, shown in Figure 12 on page 37, blinks while the module is acquiring
data.
The Trigger LED on the module, shown in Figure 12 on page 37, is amber when the module iswaiting for an external digital trigger, threshold trigger, or Sync Bus trigger (the module
must have been configured for an external digital trigger, threshold trigger, or Sync Bus
trigger), green when the module has been triggered, or off when the module is idle.

Input Triggers
A trigger is an event that occurs based on a specified set of conditions.
On the DT9838 module, you can specify a start trigger source and a reference trigger source.
Pre-trigger data acquisition starts when the start trigger event occurs. When the reference
trigger event occurs, pre-trigger data acquisition stops and post-trigger acquisition starts.
Post-trigger acquisition stops when the number of samples you specify for the post-trigger
scan count has been reached. Refer to page 105 for more information.
The Trigger LED on the module, shown in Figure 12 on page 37, is amber when the module iswaiting for an external digital trigger or analog threshold trigger (the module must have been
configured for an external digital trigger or analog threshold trigger), green when the module
has been triggered, or off when the module is idle.

Start Trigger Sources
The DT9838 module supports the following sources for the start trigger:• Software trigger – A software trigger event occurs when you start the analog input
operation (the computer issues a write to the module to begin conversions). Using
software, specify the start trigger source as a software trigger.
• External digital (TTL) trigger – An external digital (TTL) trigger event occurs when theDT9838 module detects either a rising-edge (positive) or falling-edge (negative) transitionon the signal connected to the Ext Trigger pins (pin 3 and 4) of the External Trigger andTachometer (J6) connector on the module. Using software, specify the start trigger source
as an external, positive digital (TTL) trigger or an external, negative digital (TTL) trigger.
• Threshold trigger – A threshold trigger event occurs when the signal on a specified
analog input channel rises above or falls below a programmable threshold level. Using
software, specify the following parameters:
 Start trigger source – Specify a positive (low-to-high transition) threshold trigger if you
want to trigger when the signal rises above a threshold level, or a negative(high-to-low transition) threshold trigger if you want to trigger when the signal falls
below a threshold level.
 Threshold channel – Specify any one of the analog input channels as the thresholdinput channel.
 Threshold level – Specify a value between –250 mV and +250 mV as the thresholdlevel.

107

Chapter 5

Note: If you choose a threshold trigger as both the start trigger and the reference trigger,
the threshold channel and threshold level must be the same; otherwise, the thresholdchannel and threshold level of the reference threshold trigger will be used for both trigger
sources. The polarity of the trigger (positive or negative going) can be different for eachtrigger source.

• Sync Bus trigger – When multiple DT9838 modules (or multiple DT9838 and DT9837
Series modules) are connected together using the Sync Bus (RJ45) connector, you can use
the Sync Bus trigger as the start trigger of the slave module by setting the synchronization
mode of module to Slave. In this configuration, any other start trigger for the slave
module is ignored. Refer to page 112 for more information on this configuration.

Reference Trigger Sources
The DT9838 module supports the following sources for the reference trigger:• External digital (TTL) trigger – An external digital (TTL) reference trigger event occurs
when the DT9838 module detects either a rising-edge (positive) or falling-edge (negative)
transition on the signal connected to the Ext Trigger pins (pin 3 and 4) of the External
Trigger and Tachometer (J6) connector on the module. Using software, specify the start
trigger source as an external, positive digital (TTL) trigger or an external, negative digital(TTL) trigger.
• Threshold trigger – A threshold reference trigger event occurs when the signal on a
specified analog input channel rises above or falls below a programmable threshold level.
Using software, specify the following parameters:
 Start trigger source – Specify a positive (low-to-high transition) threshold trigger if you
want to trigger when the signal rises above a threshold level, or a negative(high-to-low transition) threshold trigger if you want to trigger when the signal falls
below a threshold level.
 Threshold channel – Specify any one of the analog input channels as the thresholdinput channel.
 Threshold level – Specify a value between –250 mV and +250 mV as the thresholdlevel.

Note: If you choose a threshold trigger as both the start trigger and the reference trigger,
the threshold channel and threshold level must be the same; otherwise, the thresholdchannel and threshold level of the reference threshold trigger will be used for both trigger
sources. The polarity of the trigger (positive or negative going) can be different for eachtrigger source.

• Sync Bus trigger – When multiple DT9838 modules (or multiple DT9838 and DT9837
Series modules) are connected together using the Sync Bus (RJ45) connector, you can set
the reference trigger of a slave DT9838 module to Sync Bus if you want to receive a Sync
Bus trigger from one of the other modules to stop pre-trigger acquisition and start
post-trigger acquisition. Refer to page 112 for more information on this configuration.

108

Principles of Operation

Data Format
The DT9838 module uses offset binary data encoding, where 000000 represents –250 mV andFFFFFFh represents +250 mV. Use software to specify the data encoding as binary. The ADC
outputs FFFFFFh for above-range signals, and 000000 for below-range signals.
Before you begin acquiring data, you must allocate buffers to hold the data. An event is raised
whenever a buffer is filled. This allows you to move and/or process the data as needed.

Note: We recommend that you allocate a minimum of two buffers that can contain evenmultiples of 256 samples.

Data is written to multiple allocated input buffers continuously in blocks; when no more
empty buffers are available, the operation stops. The data is gap-free.

Error Conditions
DT9838 module reports overrun errors by sending an overrun event to the application
program. If this error condition occurs, the module stops acquiring and transferring data to
the host computer. To avoid this error, try one or more of the following:• Reduce the sample rate
• Close any other applications that are running• Run the program on a faster computer109

Chapter 5

Tachometer Input Features
You can connect a tachometer signal with a range of ±30 V to pins 1 and 2 of the External
Trigger and Tachometer (J6) connector on the DT9838 module. This signal has a maximum
frequency of 1 MHz and a minimum pulse width of 0.4 s. The threshold voltage is fixed at+2 V with 0.5 V of hysteresis.
You can measure the frequency or period of the tachometer input signal to calculate therotation speed for high-level (±30 V) tachometer input signals. An internal 12 MHz counter isused for the measurement, yielding a resolution of 83 ns (1/12 MHz).
You can read the number of counts between two consecutive starting edges of the tachometer
input signal by including channel 4 in the analog input channel list. The starting edge is
programmable (either rising or falling).
Using software commands, you can specify the following parameters for the tachometer
input:• The starting edge of the tachometer input signal to use for the measurement (rising or
falling edge).
• A flag (called Stale) indicating whether or not the data is new. If the Stale flag is set as
Used (the default value), the most significant bit (MSB) of the value is set to 0 to indicate
new data; reading the value before the measurement is complete returns an MSB of 1. If
the Stale flag is set to Not Used, the MSB is always set to 0.
When the operation is started, the internal 12 MHz counter starts incrementing when it
detects the first starting edge of the tachometer input and stops incrementing when it detects
the next starting edge of the tachometer input. When the measurement is complete, thecounter remains idle until it is read. On the next read, either 0 or the current value of thetachometer input (from the previous measurement operation) is returned depending on themodule and the tachometer settings, described above, and the next operation is started
automatically.
The software automatically synchronizes the value of the tachometer input with the analog
input measurements, so that all measurements are correlated in time. The tachometer input istreated like any other channel in the analog input channel list; therefore, all the triggering andconversion modes supported for analog input channels are supported for the tachometer
input.
When you read the value of the tachometer input as part of the analog input data stream, you
might see results similar to the following:110Principles of Operation
Table 4: An Example of Reading the Tachometer Input as Part of the Analog Input Data StreamTime

A/D Value

Tachometer
Input Value

10

5002

0

Operation started, but is not complete

20

5004

0

Operation not complete

30

5003

0

Operation not complete

40

5002

12373

Operation complete

50

5000

12373

Next operation started, but is not complete

60

5002

12373

Operation not complete

70

5004

12373

Operation not complete

80

5003

14503

Operation complete

90

5002

14503

Next operation started, but is not complete

Status of Operation

Using the count that is returned from the tachometer input, you can determine the following:• Frequency of a signal pulse (the number of periods per second). You can calculate thefrequency as follows: Frequency = 12 MHz/(Number of counts – 1)
where 12 MHz is the internal counter/timer clock frequency
For example, if the count is 21, the measured frequency is 600 kHz (12 MHz/20).
• Period of a signal pulse. You can calculate the period as follows: Period = 1/Frequency
 Period = (Number of counts – 1)/12 MHz
where 12 MHz is the internal counter/timer clock frequency

111

Chapter 5

Synchronizing Acquisition on Multiple Modules
DT9838 modules provide a Sync Bus (RJ45) connector that you can use to connect andsynchronize multiple DT9838 modules.

Note: Note that you can also connect DT9837A, DT9837B, and/or DT9837C modules to theDT9838 module in this configuration. Refer to the DT9837 Series User’s Manual for more
information.

In this scheme, one module is the master and the other modules are the slave. You specify thesynchronization mode (master, slave, or none) of the A/D subsystem using software.
When configured as a master, the Sync Bus connector outputs trigger and clock signals. Whenconfigured as a slave, the Sync Bus connector accepts trigger and clock signals from themaster; the start trigger source on the slave module in is ignored in this configuration since
the Sync Bus is used as the start trigger. When configured as none (the default mode), theDT9838 module uses the USB clock instead of the Sync Bus connector. The synchronization
mode remains set until changed or until the application exits.
You can connect multiple modules in one of two ways. Figure 53 shows how to connect amaximum of two DT9838 modules by daisy chaining them together through the Sync Bus
connector. Figure 54 shows how to connect a maximum of four DT9838 modules by using an
RJ45 distribution panel, such as the EP386, where the panel contains four RJ45 connectors thatare wired in parallel.

Host PC

USB
Port 1

InputsDT9838MasterMasterSynchronization Mode is Master.
Start Trigger can be Software, External
Digital Trigger, or Threshold Trigger.

USB

Reference Trigger can be External Digital
Trigger or Threshold Trigger.
Sync Bus (RJ45)

DeviceUnder Test

DT9838Slave
InputsUSB
Port 2USB

Slave
Synchronization Mode is Slave.
Start Trigger is ignored (Sync Bus is used).
Reference Trigger can be External Digital
Trigger, Threshold Trigger, or Sync Bus.
(Sync Bus is generally used in thisconfiguration.)

Figure 53: Synchronizing Two DT9838 Modules by Daisy Chaining the Sync Bus Connectors

112

Principles of Operation

MasterSynchronization Mode is Master.

Host PC

Start Trigger can be Software, External
Digital Trigger, or Threshold Trigger.

USB
Port 1

Reference Trigger can be External Digital
Trigger, or Threshold Trigger.

InputsDeviceUnder Test

DT9838MasterUSB
Port 2

USB
Port 3

USB

USB
Port 4

EP386
RJ45 Distribution
Panel(connectors wired

Sync Bus

USB
DT9838Slave

Sync Bus

InputsUSB

InputsDT9838Slave

Sync Bus

USB
DT9838Slave

Sync Bus

InputsSlave
Synchronization Mode is Slave.
Start Trigger is ignored (Sync Bus is used).
Reference Trigger can be External Digital Trigger, Threshold
Trigger, or Sync Bus. (Sync Bus is generally used in this

* The RJ45 cables must be less than 1 foot in length. For
minimum clock skew, the master module must be less than 4
inches away from the RJ45 distribution panel.

Figure 54: Synchronizing Four DT9838 Modules Using the EP386 RJ45 Distribution Panel(Shown Using an External Trigger)

When synchronizing multiple modules, start the slave modules before starting the mastermodule. When the master DT9838 module is triggered (using the software trigger, external
digital trigger, or threshold trigger), both the master and the slave modules start acquiring
data at the same time (within one A/D conversion of the clock). Note that you can set theclock rate to be the same or different on each module.

113

Chapter 5

Note: It is important that you start the slave modules first, followed by the master module
so that the slave receives the appropriate clock and trigger signals from the master.
If you start the master module before the slaves, the slaves never start; you will see a delay of
approximately 20 seconds if you try to stop or abort the analog input operation on a slave
module that is waiting for a trigger.

When you stop the master module, the slaves continue to run and return data until you stop
the analog input subsystem on the slave modules. Be sure to stop the analog input subsystems
on all slave modules before disconnecting the cable from the Sync Bus connectors.

Triggering DT9838 and DT9837 Series Modules Using the Sync Bus
If you are connecting the DT9838 module to a DT9837 Series module using the Sync Bus
trigger, be aware of triggering limitations.
The DT9837 Series supports the following start trigger sources: software, external digitaltrigger, and threshold trigger. For the reference trigger, the DT9837 Series supports only thethreshold trigger source. When configured as a slave, the DT9837 processes a single Sync Bus
trigger; the Sync Bus trigger is considered the start trigger and is received and/or driven out
as such.
Consider the case where the DT9838 is the master and a DT9837 Series module is the slave, as
shown in Figure 55.

Host PC

USB
Port 1

InputsDT9838MasterUSB
Port 2Start Trigger can be Software, External
Digital Trigger, or Threshold Trigger.

USB

Reference Trigger can be External Digital
Trigger, or Threshold Trigger.
Sync Bus(RJ45)

DeviceUnder Test

DT9837 Series Slave
Synchronization Mode is Slave.
USB

InputsDT9837
SeriesSlave

DT9838 Master
Synchronization Mode is Master.

Start Trigger is ignored (Sync Bus is used).
Reference Trigger can be Threshold trigger,or you can use software to stop the slaveand correlate the data.

Figure 55: Synchronizing a Master DT9838 Module and a Slave DT9837 Series Module
Using the Sync Bus Connector

114

Principles of Operation
In this case, the start trigger on the master DT9838 can be a software trigger, external digitaltrigger, or threshold trigger. The reference trigger on the master DT9838 module can be an
external digital trigger or threshold trigger.
The start trigger on the slave DT9837 Series module is ignored, since the Sync Bus is used as
the start trigger. The reference trigger on the slave DT9837 Series can be the threshold trigger,or you can use software to stop the DT9837 Series module and correlate the data.
Now, consider the case where the DT9837 Series is the master and a DT9838 module is theslave, as shown in Figure 56.

Host PC

USB
Port 1

USB
Port 2

DT9837 Series Master
Synchronization Mode is Master.
Start Trigger can be Software, External
Digital Trigger, or Threshold Trigger.

InputsDT9837
SeriesMasterUSB

Reference Trigger can be Threshold, or you
can use software to stop the master.
Sync Bus(RJ45)

DeviceUnder Test

DT9838 Slave
Synchronization Mode is Slave.
USB

DT9838Slave
InputsStart Trigger is ignored (Sync Bus is used).
Reference Trigger can be External Digital
Trigger, or Threshold Trigger, or you can
use software to stop the slave and correlate
the data.

Figure 56: Synchronizing a Master DT9837 Series Module and a Slave DT9838 Module
Using the Sync Bus Connector

In this case, the start trigger on the master DT9837 Series module can be a software, external
digital, or threshold trigger. The reference trigger on the master DT9837 Series module can be
the threshold trigger.
The start trigger on the slave DT9838 is ignored, since the Sync Bus is used as the start trigger.
The reference trigger on the slave DT9838 module can be an external digital trigger orthreshold trigger (the Sync Bus trigger is not supported as a reference trigger in thisconfiguration), or you can use software to stop the DT9838 module and correlate the data.

115

Chapter 5116

6Supported Device Driver Capabilities
Data Flow and Operation Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Triggered Scan Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Data Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Current and Resistance Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Thermocouple, RTD, and Thermistor Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
IEPE Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Bridge and Strain Gage Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Start Triggers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Reference Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Clocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Counter/Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Tachometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

117

Chapter 6
The DT9838 Device Driver provides support for the analog input (A/D) subsystems. For
information on how to configure the device driver, refer to page 34.
Table 5: DT9838 Subsystems
DT9838
Total Subsystems on Module

A/D

D/A

DIN

DOUT

C/T

1

0

0

0

0

TACH QUAD
10

The tables in this chapter summarize the features available for use with the DT-Open Layers
for .NET Class Library and the DT9838 module. The DT-Open Layers for .NET Class Libraryprovides properties that return support information for specified subsystem capabilities.
The first row in each table lists the subsystem types. The first column in each table lists all
possible subsystem capabilities. A description of each capability is followed by the property
used to describe that capability in the DT-Open Layers for .NET Class Library.

Note: The following tables include the capabilities that can be queried. However, some
capabilities may not be supported by your device. Blank fields represent unsupported
options.

For more information, refer to the description of these properties in the DT-Open Layers for.NET Class Library on help or DT-Open Layers for .NET Class Library User’s Manual.

118

Supported Device Driver Capabilities

Data Flow and Operation Options
Table 6: Data Flow and Operation Options
DT9838Single-Value Operation Support
SupportsSingleValue

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Yes

Simultaneous Single-Value Output Operations
SupportsSetSingleValues
Continuous Operation Support
SupportsContinuous

Yes

Yesa

Continuous Operation until Trigger
SupportsContinuousPreTrigger
Continuous Operation before & after Trigger
SupportsContinuousPrePostTrigger
Waveform Operations Using FIFO Only
SupportsWaveformModeOnly
Simultaneous Start List Support
SupportsSimultaneousStart

Yes

Supports Programmable Synchronization Modes
SupportsSynchronization

Yes

Synchronization Modes
SynchronizationMode

None,
Master,Slave

Interrupt Support
SupportsInterruptOnChange
FIFO Size, in Samples
FifoSize

8 kSamples

Muting and Unmuting the Output Voltage
SupportsMute
Auto-Calibrate Support
SupportsAutoCalibratea. You read the tachometer input channel in the analog input data stream by specifying channel 4 in the A/D channel
list.

119

Chapter 6

Buffering
Table 7: Buffering Options
DT9838

A/D

Buffer Support
SupportsBufferingYes

Single Buffer Wrap Mode Support
SupportsWrapSingle

Yes

Inprocess Buffer Flush Support
SupportsInProcessFlush

Yes

D/A

DIN

DOUT

C/T

TACH QUAD

C/T

TACH QUAD

Triggered Scan Mode
Table 8: Triggered Scan Mode Options
DT9838

A/D

D/A

DIN

DOUT

Triggered Scan Support
SupportsTriggeredScan
Maximum Number of CGL Scans per Trigger
MaxMultiScanCount
1

0

0

0

0

0

Maximum Retrigger Frequency
MaxRetriggerFreq

0

0

0

0

0

0

Minimum Retrigger Frequency
MinRetriggerFreq

0

0

0

0

0

0

C/T

TACH QUAD

Data Encoding
Table 9: Data Encoding Options
DT9838Binary Encoding Support
SupportsBinaryEncoding
Twos Complement Support
SupportsTwosCompEncoding
Returns Floating-Point Values
ReturnsFloats

120

A/D
Yes

D/A

DIN

DOUT

Yes

Supported Device Driver Capabilities

Channels
Table 10: Channel Options
DT9838

A/D

Number of Channels
NumberOfChannels

D/A

DIN

DOUT

C/T

4a

TACH QUAD
1a

SE Support
SupportsSingleEnded
SE Channels
MaxSingleEndedChannels
DI Support
SupportsDifferential

Yes

DI Channels
MaxDifferentialChannels

4

Maximum Channel-Gain List Depth
CGLDepth

5aSimultaneous Sample-and-Hold Support
SupportsSimultaneousSampleHold

Yes

Channel-List Inhibit
SupportsChannelListInhibit
Support MultiSensor Inputs
SupportsMultiSensor
Bias Return Termination Resistor Support
SupportsInputTerminationa. Four analog input channels are supported and 1 tachometer channel is supported. The analog input
channels are numbered 0 to 3. You read the tachometer input channel by specifying channel 4 in the A/Dchannel list.

Gain
Table 11: Gain Options
DT9838

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Programmable Gain Support
SupportsProgrammableGain
Number of Gains
NumberOfSupportedGains

1

Gains Available
SupportedGains

1121

Chapter 6

RangesTable 12: Range Options
DT9838

A/D

Number of Voltage Ranges
NumberOfRanges

1

Available Ranges
SupportedVoltageRanges±0.25 V

D/A

DIN

DOUT

C/T

TACH QUAD

Resolution
Table 13: Resolution Options
DT9838

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Software Programmable Resolution
SupportsSoftwareResolution
Number of Resolutions
NumberOfResolutions

1

1

Available Resolutions
SupportedResolutions

24

31

Current and Resistance Support
Table 14: Current and Resistance Support Options
DT9838Current Support
SupportsCurrent
Current Output Support
SupportsCurrentOutput
Resistance Support
SupportsResistance
Software Programmable External Excitation Current Source
for Resistance
SupportsExternalExcitationCurrentSrc
Software Programmable Internal Excitation Current Source
SupportsInternalExcitationCurrentSrc
Available Excitation Current Source Values
SupportedExcitationCurrentValues

122

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Supported Device Driver Capabilities

Thermocouple, RTD, and Thermistor Support
Table 15: Thermocouple, RTD, and Thermistor Support Options
DT9838

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Thermocouple Support
SupportsThernocouple
RTD Support
SupportsRTD
Thermistor Support
SupportsThermistor
Voltage Converted to Temperature in Hardware
SupportsTemperatureDataInStream
Supported Thermocouple Types
ThermocoupleType
Supports CJC Source Internally in Hardware
SupportsCjcSourceInternal
Supports CJC Channel
SupportsCjcSourceChannel
Available CJC Channels
CjcChannel
Supports Interleaved CJC Values in Data Stream
SupportsInterleavedCjcTemperaturesInStream
Supported RTD Types
RTDType
RTD R0 Coefficient
RtdR0
Supports Programmable Filters
SupportsTemperatureFilters
Programmable Filter Types
TemperatureFilterType123

Chapter 6

IEPE Support
Table 16: IEPE Support Options
DT9838

A/D

D/A

DIN

DOUT

C/T

TACH QUADIEPE Support
SupportsIEPE
Software Programmable AC Coupling
SupportsACCoupling
Software Programmable DC Coupling
SupportsDCCoupling
Software Programmable External Excitation Current Source
SupportsExternalExcitationCurrentSrc
Software Programmable Internal Excitation Current Source
SupportsInternalExcitationCurrentSrc
Available Excitation Current Source Values
SupportedExcitationCurrentValues

Bridge and Strain Gage Support
Table 17: Bridge and Strain Gage Support Options
DT9838Bridge Support
SupportsBridge
Supported Bridge Configurations
BridgeConfiguration
Strain Gage Support
SupportsStrainGage
Supported Strain Gage Bridge Configurations
StrainGageBridgeConfiguration

A/D
Yes
Full Bridge
Half Bridge
Quarter Bridge
Yes
Full -Bridge Bending
Full-Bridge Bending Poisson
Full-Bridge Axial Poisson
Half-Bridge Poisson
Half-Bridge Bending
Quarter-Bridge
Quarter-Bridge Temp Comp

External Excitation Voltage
SupportsExternalExcitationVoltage
Internal Excitation Voltage
SupportsInternalExcitationVoltage

Yes

Shunt Calibration
SupportsShuntCalibration

Yes

Voltage Excitation Per Channel
SupportedPerChannelVoltageExcitation

124

Minimum Excitation Voltage
MinExcitationVoltage

0 V DC

Maximum Excitation Voltage
MaxExcitationVoltage

10 V DC

D/A

DIN

DOUT

C/T

TACH QUAD

Supported Device Driver Capabilities

Start Triggers
Table 18: Start Trigger Options
DT9838

A/D

Software Trigger Support
SupportsSoftwareTrigger

Yesa

External Positive TTL Trigger Support
SupportsPosExternalTTLTrigger

Yesa

External Negative TTL Trigger Support
SupportsNegExternalTTLTrigger

Yesa

D/A

DIN

DOUT

C/T

TACH QUAD
Yes

External Positive TTL Trigger Support for Single-Value Operations
SupportsSvPosExternalTTLTrigger
External Negative TTL Trigger Support for Single-Value Operations
SupportsSvNegExternalTTLTrigger
Positive Threshold Trigger Support
SupportsPosThresholdTrigger

Yesa

Negative Threshold Trigger Support
SupportsNegThresholdTrigger

Yesa

Digital Event Trigger Support
SupportsDigitalEventTrigger
a. The start trigger also is used for the tachometer input channel (channel 4) if it is specified as part of the analog input channel list.
To specify the Sync Bus as the start trigger for the module, set the SynchronizationMode of the A/D subsystem to Slave; any otherstart trigger for the module is then ignored.

Reference Triggers
Table 19: Reference Trigger Options
DT9838A/D

External Positive TTL Trigger Support
SupportsPosExternalTTLTrigger

Yesa

External Negative TTL Trigger Support
SupportsNegExternalTTLTrigger

Yesa

Positive Threshold Trigger Support
SupportsPosThresholdTrigger

Yesa

Negative Threshold Trigger Support
SupportsNegThresholdTrigger

Yesa

D/A

DIN

DOUT

C/T

TACH QUAD

Digital Event Trigger Support
SupportsDigitalEventTrigger
Sync Bus Support
SupportsSyncBusTrigger

Yesa

Analog Input Channels Supported for the Threshold Trigger
SupportedThresholdTriggerChannels

0, 1, 2, 3

Post-Trigger Scan Count Support
SupportsPostTriggerScanCountYes

a. The reference trigger also is used for the tachometer input channel (channel 4) if it is specified as part of the analog input
channel list.

125Chapter 6

ClocksTable 20: Clock Options
DT9838Internal Clock Support
SupportsInternalClock

A/D

D/A

DIN

DOUT

C/T

TACH

Yesa

External Clock Support
SupportsExternalClock

Yes

Simultaneous Input/Output on a Single Clock Signal
SupportsSimultaneousClocking
Base Clock Frequency
BaseClockFrequency

27487790

12 MHzMaximum Clock Divider
MaxExtClockDivider

1.0

1.0

Minimum Clock Divider
MinExtClockDivider

1.0

1.0

Maximum Frequency
MaxFrequency

52.734 kHz

6 MHz

Minimum Frequency
MinFrequency

195.3 Hz0.00559 Hz

a. The internal clock is also used to pace the tachometer input operation if the tachometer input channel (channel 4) if it isspecified as part of the analog input channel list.

126

QUAD

Supported Device Driver Capabilities

Counter/Timers
Table 21: Counter/Timer Options
DT9838

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Cascading Support
SupportsCascading
Event Count Mode Support
SupportsCount
Generate Rate Mode Support
SupportsRateGenerate
One-Shot Mode Support
SupportsOneShot
Repetitive One-Shot Mode Support
SupportsOneShotRepeat
Up/Down Counting Mode Support
SupportsUpDown
Edge-to-Edge Measurement Mode Support
SupportsMeasureContinuous Edge-to-Edge Measurement Mode Support
SupportsContinuousMeasureHigh to Low Output Pulse Support
SupportsHighToLowPulse
Low to High Output Pulse Support
SupportsLowToHighPulse
Variable Pulse Width Support
SupportsVariablePulseWidth
None (internal) Gate Type Support
SupportsGateNone
High Level Gate Type Support
SupportsGateHighLevel
Low Level Gate Type Support
SupportsGateLowLevel
High Edge Gate Type Support
SupportsGateHighEdge
Low Edge Gate Type Support
SupportsGateLowEdge
Level Change Gate Type Support
SupportsGateLevel
Clock-Falling Edge Type
SupportsClockFalling
Clock-Rising Edge Type
SupportsClockRisingGate-Falling Edge Type
SupportsGateFalling
Gate-Rising Edge Type
SupportsGateRisingInterrupt-Driven Operations
SupportsInterrupt

127Chapter 6

Tachometers
Table 22: Tachometer Options
DT9838

128

A/D

D/A

DIN

DOUT

C/T

TACH QUAD

Tachometer Falling Edges
SupportsFallingEdge

Yes

Tachometer Rising Edges
SupportsRisingEdge

Yes

Tachometer Stale Data Flag
SupportsStaleDataFlag

Yes

7
Troubleshooting
General Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Technical Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
If Your Module Needs Factory Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

129

Chapter 7

General Checklist
Should you experience problems using a DT9838 module, do the following:
1. Read all the documentation provided for your product, including any “Read This First”
information.
2. Check the DT Omni software for any README files and ensure that you have used thelatest installation and configuration information available.
3. Check that your system meets the requirements stated in the README file on page 28.
4. Check that you have installed your hardware properly using the instructions in
Chapter 2.
5. Check that you have installed and configured the device driver properly using the
instructions in Chapter 2.
6. Check that you have wired your signals properly using the instructions in Chapter 3.
7. Search the Knowledgebase in the Support section of the web site (at www.mccdaq.com)
for an answer to your problem.
If you still experience problems, try using the information in Table 23 to isolate and solve theproblem. If you cannot identify the problem, refer to page 132.
Table 23: Troubleshooting Problems
Symptom

Possible Cause

Possible Solution

Module is notrecognized

You plugged the module into
your computer before installingthe device driver.

From the Control Panel > System > Hardware > Device
Manager, uninstall any unknown devices (showing ayellow question mark). Then, run tun the DT Omni setup
program to install the USB device drivers, and reconnect
your USB module to the computer.

Module does not
respond.

The module configuration isincorrect.

Check the configuration of your device driver; see theinstructions in Chapter 2.

The module is damaged.

Contact Data Translation for technical support; refer topage 132.

Loose connections or vibrations
exist.

Check your wiring and tighten any loose connections or
cushion vibration sources; see the instructions in
Chapter 3.

The module is overheating.

Check environmental and ambient temperature; consult
the module’s specifications on page 146 of this manualand the documentation provided by your computer
manufacturer for more information.

Electrical noise exists.

Check your wiring and either provide better shielding or
reroute unshielded wiring; see the instructions in
Chapter 3.

Intermittent
operation.

130

Troubleshooting
Table 23: Troubleshooting Problems (cont.)
Symptom

Possible Cause

Device failure
error reported.

The DT9838 module cannot
communicate with the Microsoft
bus driver or a problem with thebus driver exists.

Check your cabling and wiring and tighten any loose
connections; see the instructions in Chapter 3.

The DT9838 module wasremoved while an operation was
being performed.

Ensure that your DT9838 module is properly connected;
see the instructions in Chapter 2.

An open connection exists.

Check your wiring and fix any open connections; see theinstructions in Chapter 3.

A transducer is not connected tothe channel being read.

Check the transducer connections; see the instructions in
Chapter 3.

Incorrect channel configuration.

Check your wiring and ensure that what you specify insoftware matches your hardware configuration; see theinstructions in Chapter 3.

The DT9838 module is out ofcalibration.

DT9838 modules are calibrated at the factory. If you want
to readjust the calibration of the analog input or analog
output circuitry, refer to Chapter 8 starting on page 135.

Your operating system does nothave the appropriate Service
Pack installed.

Ensure that you load the appropriate Windows Service
Pack. If you are unsure of whether you are using USB 2.0
or USB 1.1, run the Open Layers Control Panel applet,
described in Chapter 2.

Standby mode is enabled onyour PC.

For some PCs, you may need to disable standby modeon your system for proper USB 2.0 operation. Consult
Microsoft for more information.

Data appears to
be invalid.

USB 2.0 is notrecognized.

Possible Solution

131Chapter 7

Technical Support
If you have difficulty using a DT9838 module, Data Translation’s Technical Support
Department is available to provide technical assistance.
To request technical support, go to our web site at http://www.mccdaq.com and click on the
Support link.
When requesting technical support, be prepared to provide the following information:• Your product serial number• The hardware/software product you need help on• The version of the Omni software that you are using• Your contract number, if applicable
If you are located outside the USA, contact your local distributor; see our web site(www.mccdaq.com) for the name and telephone number of your nearest distributor.

132

Troubleshooting

If Your Module Needs Factory Service
Most hardware models can be functionally tested, evaluated for repairs (if needed), andcalibrated to factory specifications. An RMA# must be obtained from Applications
Engineering in advance of sending any product back to Measurement Computing (DataTranslation is a Measurement Computing company). Customers outside the USA must
contact their local distributor for a return procedure. Calibration certificates for most analog
models can be obtained for a fee (certificate must be requested at time of RMA# assignment).

133

Chapter 7134

8Calibration
Using the Calibration Utility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Calibrating the Analog Input Subsystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Calibrating the Internal Analog Output Circuity (Excitation Voltage) . . . . . . . . . . . . . . . 139

135

Chapter 8

Using the Calibration Utility
The DT9838 module is calibrated at the factory and should not require calibration for initialuse. We recommend that you check and, if necessary, readjust the calibration of the DT9838
module every six months using the DT9838 Calibration Utility.

Note: Ensure that you installed the DT9838 Device Driver prior to using the DT9838
Calibration Utility.

Start the DT9838 Calibration Utility as follows:
1. Click Start from the Task Bar.
2. Select Programs | Data Translation, Inc | Calibration |DT9838 Calibration Utility.
The main menu of the DT9838 Calibration Utility appears.
3. Select the module to calibrate, and then click OK.
Once the DT9838 Calibration Utility is running, you can calibrate the analog input circuitry(either automatically or manually), described on page 137, and/or calibrate the internal
analog output circuitry that is responsible for providing the excitation voltage for the module,
described on page 139.

136

Calibration

Calibrating the Analog Input Subsystem
This section describes how to use the DT9838 Calibration Utility to calibrate the analog input
subsystem of a DT9838 module.
You must calibrate each analog input channel separately.

IMPORTANT: Before calibrating the analog input subsystem, ensure that you have attached
all of your sensors and configured the sampling frequency of the device. This ensures that theproper current is detected and the proper excitation value is supplied to each channel.

Connecting a Precision Voltage Source
To calibrate the analog input circuitry, you need to connect an external precision voltage
source capable of generating +240 mV to the analog input channels of the DT9838 module.

Using the Auto-Calibration Procedure
Auto-calibration is the easiest to use and is the recommended calibration method. To
auto-calibrate the analog input subsystem, do the following:
1. Select the A/D Calibration tab of the DT9838 Calibration Utility.
2. Under the Channel Number drop-down list box in the Automatic Calibration area, selectthe analog input channel to calibrate.
3. Set the voltage supply on your selected channel to 0.0000V.
4. Enter the sampling frequency at which you want to run (and calibrate) the DT9838
module.
5. Click the Auto Calibration Start button.
A message appears notifying you to verify that 0.0000 V is applied to the channel.
6. Verify that the supplied voltage to your selected channel is 0.0000 V, and then click OK.
The offset value is calibrated. When the offset calibration is complete, a message appears notifying
you to set the input voltage of the channel to +240 mV.
7. Check that the supplied voltage to your selected channel is +240 mV, and then click OK.
The gain value is calibrated and a completion message appears.
8. Repeat steps 2 through 7 for the remaining analog input channels.

Note: At any time, you can click Restore Factory Settings to reset the A/D calibration
values to their original factory settings. This process will undo any auto or manual
calibration settings.

137

Chapter 8

Using the Manual Calibration Procedure
If you want to manually calibrate the analog input circuitry instead of auto-calibrating it, do
the following for each analog input channel:
1. Select the analog input channel that you want to calibrate.
2. Enter the sampling frequency at which you want to run (and calibrate) the DT9838
module.
3. Adjust the offset as follows:a. Verify that 0.0000 V is applied to the selected analog input channel.
b. Under Sampling, click Start to start sampling data from the selected analog input
channel.
The current voltage reading for this channel is displayed in the AD Value text box.
c.

Adjust the offset by entering values between 0 and 255 in the Offset edit box, or byclicking the up/down buttons until the AD Value is 0.0000 V.

d. Under Sampling, click Stop to stop sampling data from the selected analog input
channel.
4. Adjust the gain as follows:a. Verify that +240 mV is applied to the selected analog input channel.
b. Under Sampling, click Start to start sampling data from the selected analog input
channel.
The current voltage reading for this channel is displayed in the AD Value text box.
c.

Adjust the gain by entering values between 0 and 255 in the Gain edit box, or byclicking the up/down buttons until the AD Value is 240 mV.

d. Under Sampling, click Stop to stop sampling data from the selected analog input
channel.
5. Repeat steps 1 through 5 for the remaining analog input channels.

Note: At any time, you can click Restore Factory Settings to reset the A/D calibration
values to their original factory settings. This process will undo any auto or manual
calibration settings.

138

Calibration

Calibrating the Internal Analog Output Circuity(Excitation Voltage)
This section describes how to use the DT9838 Calibration Utility to calibrate the internal
analog output circuitry that is used to generate the excitation voltage for the DT9838 module.
This procedure assumes that you have connected a STP STRAIN General-Purpose Accessory,
STP STRAIN 120 Quarter-Bridge Completion Accessory, or STP STRAIN 350 Quarter-Bridge
Completion Accessory to the DT9838 module.

Connecting a Digital Voltmeter
To calibrate the internal analog output circuitry, you need an external digital voltmeter(DVM). Connect the digital voltmeter to the STP STRAIN, STP STRAIN 120, or STP STRAIN
350 accessory as follows:
1. Connect the digital voltmeter across signals Excitation+ (pin 6) and Excitation– (pin 7) on
the STP STRAIN, STP STRAIN 120, or STP STRAIN 350 accessory.
2. Connect signals Excitation– (pin 7) to Sense– (pin 5) on the STP STRAIN, STP STRAIN
120, or STP STRAIN 350 accessory.
3. Connect signals Excitation+ (pin 6) to Sense+ (pin 4) on the STP STRAIN, STP STRAIN
120, or STP STRAIN 350 accessory.

Calibrating the Analog Output Circuitry
Once you have connected the digital voltmeter to the STP STRAIN, STP STRAIN 120, or STP
STRAIN 350 accessory, which is connected to the DT9838 module, calibrate the analog output
circuitry, as follows:
1. Select the Bridge Internal Excitation DAC Calibration tab of the DT9838 Calibration
Utility.
2. Read the value that is displayed by the digital voltmeter.
3. Enter values between 0 and 65535 in the edit box or by clicking the up/down buttons
until the value that is displayed by the digital voltmeter is 0.1 V.
4. Click Next.
5. Read the value that is displayed by the digital voltmeter.
6. Enter values between 0 and 65535 in the edit box or by clicking the up/down buttons
until the value that is displayed by the digital voltmeter is 10 V.

Note: At any time, you can click Restore Factory Settings to reset the A/D calibration
values to their original factory settings. This process will undo any auto or manual
calibration settings.

7. When you are finished calibrating the module, click Done to close the calibration utility.

139Chapter 8140ASpecifications
Analog Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Bridge Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Tachometer Input Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Trigger Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Power, Physical, and Environmental Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Regulatory Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Connector Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
External Power Supply Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

141

Appendix A

Analog Input Specifications
Table 24 lists the specifications for the A/D subsystem on the DT9838 module. Performance
specifications are typical for the operating range of 0 C to 55 C.
Table 24: A/D Subsystem Specifications
Feature

142

DT9838 Specifications

Number of analog inputs

4 differential

Resolution

24 bits

Input range±250 mV

Data encoding

offset binary

Sample rate per channel

195 Samples/s to 52734 Samples/s, simultaneous
sampling

Passband (±0.005 dB flatness)

DC to 0.453 * data rate

Group delay

39/data rate, seconds

Accuracy
Gain error:
Offset error:
Gain drift:
Offset drift:

0.02% of reading±25 V±10 ppm/C±2 V/C

Input Noise

3 Vrms

SFDR (1 kHz, –1 dB Full-Scale)

95 dB

Total Harmonic Distortion
1 kHz, –20 dB Full-Scale
10 kHz, –20 dB Full-Scale–100 dB–90 dBDC differential input impedance

20 M

Differential input voltage protection±30 V

Channel crosstalk
1 kHz:
10 kHz:>100 dB>100 dB

Maximum input voltage±40 V

ESD protection
Arc:
Contact:

8 kV
4 kV

Input FIFO

8 kSamples

Specifications

Bridge Specifications
Table 25 lists the bridge specifications for the DT9838 module.
Table 25: Bridge Excitation Specifications
FeatureDT9838 Specifications

Supported bridge configurations

Full, Half, and Quarter (Quarter-Bridge requires external
bridge completion resistor)

Internal Half-Bridge completion
resistors

10 k divider, 0.05% matching, 2 ppm/C tracking

Bridge excitation

0 V to 10 V, 167 V resolution

Bridge excitation accuracy±2 mV

Bridge excitation stability±12 V/C ±10 ppm/C

Bridge excitation noise

50 Vrms

Shunt calibration resistor

100 k, 0.1%, 25 ppm/C

Short circuit current limit

50 mA each channel

143

Appendix A

Tachometer Input Specifications
Table 26 lists the specifications for the tachometer input on the DT9838 module.
Table 26: Tachometer Input Specifications
FeatureNumber of channels
Resolution

1
31 bits per channel

Input voltage range±30 V

Threshold voltage±2 V with 0.5 V hysteresis

Maximum input frequency

1 MHz

Minimum pulse width high/low(minimum amount of time it takes a
C/T to recognize an input pulse)

0.4 sClock frequency for tachometermeasurements

12 MHz(83 ns resolution)

Input termination

144

DT9838 Specifications

None

Specifications

Trigger Specifications
Table 27 lists the specifications for the trigger on the DT9838 module.
Table 27: Trigger Specifications
FeatureTrigger sources
Internal software trigger:
External digital trigger:
Analog threshold trigger:

DT9838 Specifications
Software-initiatedSoftware-selectable
Software-selectable

External digital trigger
Input type:
Logic family:
Input logic load:
Lower threshold:
Upper threshold:
Hysteresis:
Input sink current:
Minimum pulse width high/low:
Maximum input signal:
Input termination:

Edge-sensitive, positive trigger
LVTTL inputs
1 LVTTL
1.1 V
1.3 V
0.2 V
33 A
200 ns±30 V
None

Trigger delay

1 conversion period maximum

145

Appendix A

Power, Physical, and Environmental Specifications
Table 28 lists the power, physical, and environmental specifications for the DT9838 module.
Table 28: Power, Physical, and Environmental Specifications
FeatureDT9838 Specifications

USB Power+5 V Standby:+5 V Operation with no Bridges Powered:+5 V Operation with Bridges Powereda:
Optional External Power Requirement(optimal for enhanced bridge drive capability)
Optional EP394 External Power Supply
Output:Input voltage:
Input current:
Frequency:

50 mA typical
320 mA typical
500 mA maximum (USB power only)
200 mA typical (external power supply)+5 V to 24 V @ 2 Wb

5 V @ 1.6 A
100 to 240 V AC ±10%250 mA
50 to 60 Hz

Physical Dimensions - DT9838
Length:Width:Height:Weight:8.880 inches (225.55 mm)
4.170 inches (105.92 mm)
1.575 inches (40 mm)
21.32 ounces (604.5 g)

Physical Dimensions - DT9838-OEM
Length:Width:Height:Weight:8.800 inches (223.52 mm)
3.937 inches (100 mm)
0.712 inches (18.08 mm)
5.4 ounces (153 g)

Environmental
Operating temperature range:
Storage temperature range:
Relative humidity:
Altitude:0C to55C–25C to 85C
To 95%, noncondensing
To 10,000 feeta. See Table 1 on page 29 for example configurations of bridges powered from an external supply.
b. The optional EP394 external power supply provides 5 V to enhance the bridge drive capability. Referto page 29 for more information.

146

Specifications

Regulatory Specifications
Table 29 lists the regulatory specifications for the DT9838 module.
Table 29: Regulatory Specifications
FeatureSpecifications

Emissions (EMI)FCC Part 15, Class A
EN55011:2007 (Based on CISPR-11, 2003/A2, 2006)

Immunity

EN61326-1:2006
Electrical Equipment for Measurement, Control, and Laboratory Use
EMC Requirements
EN61000-4-2:2001
Electrostatic Discharge (ESD) 4 kV contact discharge,
8 kV air discharge, 4 kV horizontal and vertical coupling planes
EN61000-4-3:2002
Radiated electromagnetic fields, 3 V/m, 80 to 1000 MHz;
3 V/m, 1.4 GHz to 2 GHz; 1 V/m, 2 GHz to 2.7 GHz
EN61000-4-4:2004
Electrical Fast Transient/Burst (EFT) 1 kV on data cables
EN61000-4-6:2003
Conducted immunity requirements, 3 Vrms on data cables
150 kHz to 80 MHz

RoHS (EU Directive 2002/95/EG)

Compliant (as of July 1st, 2006)147

Appendix A

Connector Specifications
Table 30 lists the cable and connector specifications for the DT9838 module.
Table 30: DT9838 Cable and Connector Specifications
Feature

148

DT9838 Specifications

Analog input connectors (RJ50)

Tyco 5558067-1

Tachometer/external trigger connector(4-position Screw terminal block)

Header: Phoenix Contact 1803293
Plug: Phoenix Contact 1803594

External power supply

Jack on the module: Switchcraft #L722RA
Mating plug assembly, 0.08 inch: Switchcraft #S761K

Sync Bus connector (RJ45)

Molex part number 44661-0001

USB connector

AMP 292304-2

Specifications

External Power Supply Specifications
Table 31 lists the specifications for the optional EP394 +5 V external power supply that can beused with the DT9838 module.
Table 31: External Power Supply (EP394) Specifications
FeatureSpecificationsType

FRIWO medical power supply (GPP 10)

Input voltage

100 to 240 V AC (±10%)

Input current

250 mA

Frequency

50 to 60 Hz

Efficiency

80% typical at full load

Output voltage

5V

Output current

1600 mA

Output ripple voltage

75 mV pp

Regulatory standards

UL, VDE, CE, Energy Star compliant

149

Appendix A

150

B
Connector Pin Assignments
Analog Input Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Sync Bus Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
External Trigger and Tachometer Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
External USB Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
External Power Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Screw Terminals on the STP STRAIN, STP STRAIN 120, and STP STRAIN 350 . . . . . . . 157

151

Appendix B

Analog Input Connectors
Figure 57 shows the orientation of the pins used in each of the analog input (RJ50) connectors
on the DT9838 module.

1 2 3 4 5 6 7 8 9 10

Figure 57: Analog Input (RJ50) Connector

Table 32 lists the pin assignments of the analog input (RJ50) connectors.
Table 32: Pin Assignments of the Analog Input (RJ50) Connectors
Pin

152

Signal Description

1

RSHUNT+

2

AIN+

3

AIN–

4

SENSE+

5

SENSE–

6

EXC+

7

EXC–

8

TEDS Data

9

TEDS Return

10

RSHUNT –Connector Pin Assignments

Sync Bus Connector
Figure 58 shows the orientation of the pins used in the Sync Bus (RJ45) connector (connector
J7) on the DT9838 module.

1 2 3 4 5 6 7 8

Figure 58: Sync Bus (RJ45) Connector

Table 33 lists the pin assignments of the Sync Bus (RJ45) connector.
Table 33: Sync Bus (RJ45) Connector Pin Assignments
Pin

Description

1

Clock +
(An LVDS signal for synchronizing data collection
between two modules.)2

Clock –

3

Trigger +(An LVTTL signal that is asserted low for triggering
between modules.)4

Sync +(An LVTTL signal that is asserted low for synchronizing
all the analog input signals between modules for
simultaneous sample-and-hold applications.)

5

Sync –(Connected to digital ground through a 100  resistor.)

6

Trigger –(Connected to digital ground through a 100  resistor.)

7

No Connect

8

No Connect

153

Appendix B

External Trigger and Tachometer Connector
Figure 59 shows the orientation of the screw terminals used in the External Trigger andTachometer connector (connector J6) on the DT9838 module.

(On End Near Power Supply Connector)

4

3

2

1

(On End Near Sync Bus Connector)

Figure 59: External Trigger and Tachometer Connector

Table 34 lists the screw terminal assignments for the External Trigger and Tachometer
Connector.
Table 34: External Trigger and Tachometer Connector
Screw Terminal Assignments
Pin

154

Description

1

Tachometer

2

Tachometer Return3

External Trigger

4External Trigger Return

Connector Pin Assignments

External USB Connector
Figure 60 shows the orientation of the pins used in the external USB connector (connector J8)
on the DT9838 module.

1

4

2

3

Figure 60: External USB Connector

Table 35 lists the pin assignments of the USB connector.
Table 35: J8 USB Connector Pin Assignments
Pin

Description

1

USB +5 V

2

USB Data –3

USB Data +4

USB Ground155Appendix B

External Power Connector
You can connect an external +5 V to +24 VDC power supply to the auxiliary power connector
on the DT9838 module to enhance the bridge drive capability. (Refer to page 29 for more
information on enhancing the bridge drive capability.) Figure 61 shows the layout of theexternal power connector on the DT9838 module.

Pin 1

Pin 2

Figure 61: Layout of the External Power Connector

Table 36 lists the pin assignments for the external power connector on the DT9838 module.
Table 36: Pin Assignments for the External Power Connector

156

Connector Pin Number

Signal Description

1+5 VDC to +24 VDC

2GroundConnector Pin Assignments

Screw Terminals on the STP STRAIN,STP STRAIN 120, and STP STRAIN 350
The screw terminal assignments of the STP STRAIN, STP STRAIN 120, and STP STRAIN 350
accessories, listed in Table 37, match the pin designations of the RJ50 analog input connectors
on the DT9838.
Table 37: Pin Assignments for the RJ50 Connectors
Pin

Signal Description

1

RSHUNT+

2

AIN+

3

AIN–

4

SENSE+

5

SENSE–

6

EXC+

7

EXC–

8

TEDS DATA9TEDS RETURN

10RSHUNT –157

Appendix B

158

IndexIndex
A
A/D sample clock 104
A/D subsystem, specifications 142, 143
accessories 21, 112, 113
EP394 external power supply 21, 29
STP STRAIN 120 quarter-bridge completion 19,
40
STP STRAIN 350 quarter-bridge completion 20,
40
STP STRAIN general-purpose screw terminal
panel 19, 40
administrator privileges 34
aliasing 104
analog input
calibrating 137
channel list 91
continuous operations 105
conversion modes 105
error conditions 109
single-value operations 105
triggers 107
analog input features
A/D sample clock 104
bridge configurations 92
bridge excitation 100
channels 91
connector pin assignments 39
gain 104
input ranges 104
lead wire correction 100
offset nulling 103
remote sensing 100
resolution 104
shunt calibration 101
specifications 142, 143
TEDS 103
applet, Open Layers Control Panel 131

Bbase clock frequency 126
BaseClockFrequency 126
binary data encoding 120
bridge channels
configurations 124
support 124

bridge configurations 92, 93
Full-Bridge Axial Poisson 63, 99
Full-Bridge Axial Poisson configuration 99
Full-Bridge Bending 57, 97
Full-Bridge Bending configuration 97
Full-Bridge Bending Poisson 60, 98
Full-Bridge Bending Poisson configuration 98
Half-Bridge Bending 54, 93, 96
Half-Bridge Bending configuration 96
Half-Bridge Poisson 50, 93, 95
Half-Bridge Poisson configuration 95
Quarter-Bridge 42, 93, 94
Quarter-Bridge configuration 93, 94
Quarter-Bridge Temp Comp 47, 93, 95
Quarter-Bridge Temp Comp configuration 95
bridge excitation 100
BridgeConfiguration 124
buffers 109, 120
inprocess flush 120

C
C/C++ programs 17
cablesUSB 31, 32
calibrating the module
analog input subsystem 137
internal analog output circuitry 139
running the calibration utility 136
CGLDepth 121
channel list
for analog input channels 91
specifying the tachometer 110
channel type, differential 121
channel-gain list depth 121
channels
analog input 91
number of 121
clocksbase frequency 126
external 126
internal 126
maximum external clock divider 126
maximum throughput 126
minimum external clock divider 126
minimum throughput 126
simultaneous 126

159

Indexconnecting to the host computer 31
connectors
analog input 152
external +5 V 156
external trigger 154
external USB 155
STP STRAIN 120 accessory 157
STP STRAIN 350 accessory 157
STP STRAIN accessory 157
Sync Bus 153
tachometer 154
continuous analog input
post-trigger 119
scan operations 105
continuous digital output 119
Control Panel applet 131
conventions used 10
conversion modes
continuous analog input (scan mode) 105
single-value analog input 105
conversion rate 106
customer service 133

D160

external +5 V connector 156
external clock 126
external clock divider
maximum 126
minimum 126
external negative digital trigger 107, 108, 125
external positive digital trigger 107, 108, 125
external trigger connector 154
external trigger input, wiring 70
external USB connector 155

Ffactory service 133
features 14
FifoSize 119
frequency
analog input operations 104
base clock 126
internal A/D clock 126
internal A/D sample clock 126
internal retrigger clock 120
Full-Bridge Axial Poisson 93
Full-Bridge Axial Poisson configuration 93
Full-Bridge Bending 93
Full-Bridge Bending configuration 93
Full-Bridge Bending Poisson 93
Full-Bridge Bending Poisson configuration 93

DAQ Adaptor for MATLAB 17
data encoding 109, 120
data flow modes
continuous post-trigger 119
single-value 119
DataAcq SDK 17
definitions 38
device driver 16, 34
Device Selection window 73
differential channels 121
digital trigger 107, 108
DT-Open Layers for .NET Class Library 17

gain
actual available 121
analog input 104
number of 121
general wiring recommendations 38
group delay 104

EH

encoding data 109
environmental specifications 146, 148
EP386 panel 21, 112, 113
EP394 +5 V power supply 21, 29
EP398 RJ50 cables 20, 41
error conditions 109
excitation voltage 100
calibrating 139
internal 124
minimum 124
expansion hub 32

Half-Bridge Bending configuration 93
Half-Bridge Poisson configuration 93
hardware features 14
hot-swapping 31

G

I
inprocess buffers 120
input ranges 104
internal analog output circuitry, calibrating 139
internal clock 126

Indexinternal excitation voltage 124

J
J5 connector 156

L
LabVIEW 18
lead wire correction 100
LEDs
Trigger 31, 107
USB 31, 32, 107
legacy CPL elevated 34
load cells 99
load-cells, wiring 66
LV-Link 18

Mmaster device 74
MATLAB 17
MaxDifferentialChannels 121
MaxExcitationVoltage 124
MaxExtClockDivider 126
MaxFrequency 126
MaxMultiScanCount 120
MaxRetriggerFreq 120
MinExcitationVoltage 124
MinExtClockDivider 126
MinFrequency 126
MinRetriggerFreq 120
module specifications 146, 148
multiple channels, analog input 91

Nnumber ofdifferential channels 121
gains 121
I/O channels 121
resolutions 122
scans per trigger 120
voltage ranges 122
NumberOfChannels 121
NumberOfRanges 122
NumberOfResolutions 122
NumberOfSupportedGains 121
Nyquist Theorem 104

O
offset nulling 103
Open Layers Control panel 34
Open Layers Control Panel applet 131
operation modes
continuous analog input (scan mode) 105
single-value analog input 105

Pphysical specifications 146, 148
pin assignments
analog input connector 152
external trigger and tachometer connector 154
external USB connector 155
STP STRAIN 120 accessory 157
STP STRAIN 350 accessory 157
STP STRAIN accessory 157
Sync Bus connector 153
post-trigger acquisition mode 119
post-trigger scan count 125
power 29
power specifications 146, 148
power supply 29
pressure transducers 66, 99

Q
Quarter-Bridge configuration
wiring 42
Quarter-Bridge Temp Comp configuration 93
wiring 47
QuickDAQ 72
Advanced FFT Analysis option 17
Base version 16
FFT Analysis option 16

Rrangesanalog input 104
number of 122
reference trigger 108
related documents 10
remote sensing 100
Full-Bridge Axial Poisson configuration 64
Full-Bridge Bending configuration 59
Full-Bridge Bending Poisson configuration 61
Half-Bridge Bending configuration 55
Half-Bridge Poisson configuration 52
Quarter-Bridge configuration 45

161

IndexQuarter-Bridge Temp Comp configuration 48
resolution
analog input 104
available 122
number of 122
retrigger clock frequency 120
returning modules to the factory 133
RJ45 connector
pin assignments 153
RJ50 cables 20, 41
RJ50 connector 39
RMA 133
rosette 43

Ssample rate 106
scan count, post-trigger 125
scan operations, analog input 105
SDK 17sensing 100
sensors 66, 99
shunt calibration 101, 124
Full-Bridge Axial Poisson configuration 59, 65,
103
Full-Bridge Bending configuration 59, 103
Full-Bridge Bending Poisson configuration 59, 62,
103
Half-Bridge Bending configuration 56, 102
Half-Bridge Poisson configuration 53, 102
Quarter-Bridge configuration 46, 102
Quarter-Bridge Temp Comp configuration 49,
102
simultaneous clocking 126
simultaneous sample-and-hold support 121
simultaneous start list 119
single buffer 120
single channel analog input 91
single-value operations 119
analog input 105
size, module 146
software trigger 107, 124, 125
specifications 141
analog input 142, 143environmental 146, 148
external power supply 149
physical 146, 148
power 146, 148
regulatory 147
tachometer input 144
triggers 145

162

start trigger sources 107
stopping an operation 106
STP STRAIN 120 quarter-bridge completion
accessory 19, 40
connector 157
STP STRAIN 350 quarter-bridge completion
accessory 20, 40
connector 157
STP STRAIN general-purpose accessory 19, 40
connector 157
strain gage channels
configurations 124
support 124
strain gage measurement example 76
StrainGageBridgeConfiguration 124
SupportedGains 121
SupportedResolutions 122
SupportedThresholdTriggerChannels 125
SupportedVoltageRanges 122
SupportsBinaryEncoding 120
SupportsBridge 124
SupportsBuffering 120
SupportsContinuous 119
SupportsDifferential 121
SupportsExternalClock 126
SupportsFallingEdge 128
SupportsInProcessFlush 120
SupportsInternalClock 126
SupportsInternalExcitationVoltage 124
SupportsNegExternalTTLTrigger 125
SupportsNegThresholdTrigger 125
SupportsPosExternalTTLTrigger 125
SupportsPosThresholdTrigger 125
SupportsPostTriggerScanCount 125
SupportsRisingEdge 128
SupportsShuntCalibration 124
SupportsSimultaneousClocking 126
SupportsSimultaneousSampleHold 121
SupportsSimultaneousStart 119
SupportsSingleValue 119
SupportsSoftwareTrigger 125
SupportsStaleDataFlag 128
SupportsStrainGage 124
SupportsSyncBusTrigger 125
SupportsSynchronization 119
SupportsWrapSingle 120
Sync Bus connector pin assignments 153
Sync Bus reference trigger 125
Sync Bus trigger 108
synchronization modes 119
SynchronizationMode 119

Indexsynchronizing tachometer and analog input data104
system requirements 28

Ttachometer
falling edges 110, 128
rising edges 110, 128
Stale data flag 110, 128
tachometer connector 154
tachometer input 110
specifications 144
wiring 69
technical support 132
TEDS 103threshold trigger 107, 108
channels 125
negative 125
positive 125
throughput
maximum 126
minimum 126
torque sensors 66, 99
trademark and copyright information 2transducers 66, 99
Trigger LED 31, 107
triggered scannumber of scans per trigger 120
retrigger frequency 120
triggers
analog input 107
external 107, 108
external negative digital 125
external positive digital 125
negative threshold 125
positive threshold 125
software 107, 124, 125
specifications 145
Sync Bus 108, 125
threshold 107, 108
troubleshooting
procedure 130
technical support 132
troubleshooting table 130
TTL trigger 107, 108

USB expansion hub 32
USB LED 31, 32, 107

V
Visual Basic for .NET programs 17
Visual C# programs 17
voltage ranges 104, 122
number of 122

Wwiringexternal trigger input 70
Full-Bridge Axial Poisson configuration 63
Full-Bridge Bending configuration 57
Full-Bridge Bending Poisson configuration 60
Half-Bridge Bending configuration 54
Half-Bridge Poisson configuration 50
load cells 66
Quarter-Bridge configuration 42
Quarter-Bridge Temp Comp configuration 47
tachometer input 69
voltage inputs 68
wiring recommendations 38
writing programs in
C/C++ 17
Visual Basic .NET 17
Visual C# 17

U
unpacking 27
USB cable 31, 32

163

Index164