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User Manual
iDAQ-871/873
Bridge Input Industrial DAQ
Modules
iDAQ-871_873 User Manual ii
Copyright
The documentation and the software included with this product are copyrighted 2024
by Advantech Co., Ltd. All rights are reserved. Advantech Co., Ltd. reserves the right
to make improvements in the products described in this manual at any time without
notice. No part of this manual may be reproduced, copied, translated, or transmitted
in any form or by any means without the prior written permission of Advantech Co.,
Ltd. The information provided in this manual is intended to be accurate and reliable.
However, Advantech Co., Ltd. assumes no responsibility for its use, nor for any
infringements of the rights of third parties that may result from its use.
Acknowledgments
Intel and Pentium are trademarks of Intel Corporation.
Microsoft Windows and MS-DOS are registered trademarks of Microsoft Corp.
All other product names or trademarks are properties of their respective owners.
Product Warranty (2 years)
Advantech warrants the original purchaser that each of its products will be free from
defects in materials and workmanship for two years from the date of purchase.
This warranty does not apply to any products that have been repaired or altered by
persons other than repair personnel authorized by Advantech, or products that have
been subject to misuse, abuse, accident, or improper installation. Advantech
assumes no liability under the terms of this warranty as a consequence of such
events.
Because of Advantech’s high quality-control standards and rigorous testing, most
customers never need to use our repair service. If an Advantech product is defective,
it will be repaired or replaced free of charge during the warranty period. For out-of-
warranty repairs, customers will be billed according to the cost of replacement mate-
rials, service time, and freight. Please consult your dealer for more details.
If you believe your product is defective, follow the steps outlined below.
1. Collect all the information about the problem encountered. (For example, CPU
speed, Advantech products used, other hardware and software used, etc.) Note
anything abnormal and list any onscreen messages displayed when the prob-
lem occurs.
2. Call your dealer and describe the problem. Please have your manual, product,
and any helpful information readily available.
3. If your product is diagnosed as defective, obtain a return merchandise authori-
zation (RMA) number from your dealer. This allows us to process your return
more quickly.
4. Carefully pack the defective product, a completed Repair and Replacement
Order Card, and a proof of purchase date (such as a photocopy of your sales
receipt) into a shippable container. Products returned without a proof of pur-
chase date are not eligible for warranty service.
5. Write the RMA number clearly on the outside of the package and ship the pack-
age prepaid to your dealer.
Part No. 2003087100 Edition 1
Printed in China April 2024
iii iDAQ-871_873 User Manual
Declaration of Conformity
CE
This product has passed the CE test for environmental specifications when shielded
cables are used for external wiring. We recommend the use of shielded cables. This
type of cable is available from Advantech. Please contact your local supplier for
ordering information.
Test conditions for passing also include the equipment being operated within an
industrial enclosure. In order to protect the product from damage caused by electro-
static discharge (ESD) and EMI leakage, we strongly recommend the use of CE-
compliant industrial enclosure products.
FCC Class A
This equipment has been tested and found to comply with the limits for a Class A dig-
ital device, pursuant to part 15 of the FCC Rules. These limits are designed to pro-
vide reasonable protection against harmful interference when the equipment is
operated in a commercial environment. This equipment generates, uses, and can
radiate radio frequency energy and, if not installed and used in accordance with the
instruction manual, may cause harmful interference to radio communications. Opera-
tion of this equipment in a residential area is likely to cause harmful interference. In
this event, users are required to correct the interference at their own expense.
Technical Support and Assistance
1. Visit the Advantech website at www.advantech.com/support to obtain the latest
product information.
2. Contact your distributor, sales representative, or Advantech's customer service
center for technical support if you need additional assistance. Please have the
following information ready before calling:
–Product name and serial number
–Description of your peripheral attachments
–Description of your software (operating system, version, application software,
etc.)
–A complete description of the problem
–The exact wording of any error messages
iDAQ-871_873 User Manual iv
Warnings, Cautions, and Notes
Document Feedback
To assist us with improving this manual, we welcome all comments and constructive
criticism. Please send all such feedback in writing to support@advantech.com.
Packing List
Before system installation, check that the items listed below are included and in good
condition. If any item does not accord with the list, contact your dealer immediately.
iDAQ-871
iDAQ-871 x 1
Startup Manual x 1
iDAQ-873
iDAQ-873 x 1
Startup Manual x 1
Warning! Warnings indicate conditions that if not observed can cause personal
injury!
Caution! Cautions are included to help prevent hardware damage and data
losses. For example,
“Batteries are at risk of exploding if incorrectly installed. Do not attempt
to recharge, force open, or heat the battery. Replace the battery only
with the same or equivalent type as recommended by the manufacturer.
Discard used batteries according to the manufacturer's instructions.”
Note! Notes provide additional optional information.
v iDAQ-871_873 User Manual
Safety Instructions
1. Read these safety instructions carefully.
2. Retain this user manual for future reference.
3. Disconnect the equipment from all power outlets before cleaning. Use only a
damp cloth for cleaning. Do not use liquid or spray detergents.
4. For pluggable equipment, the power outlet socket must be located near the
equipment and easily accessible.
5. Protect the equipment from humidity.
6. Place the equipment on a reliable surface during installation. Dropping or letting
the equipment fall may cause damage.
7. The openings on the enclosure are for air convection. Protect the equipment
from overheating. Do not cover the openings.
8. Ensure that the voltage of the power source is correct before connecting the
equipment to a power outlet.
9. Position the power cord away from high-traffic areas. Do not place anything over
the power cord.
10. All cautions and warnings on the equipment should be noted.
11. If the equipment is not used for a long time, disconnect it from the power source
to avoid damage from transient overvoltage.
12. Never pour liquid into an opening. This may cause fire or electrical shock.
13. Never open the equipment. For safety reasons, the equipment should be
opened only by qualified service personnel.
14. If any of the following occurs, have the equipment checked by service person-
nel:
–The power cord or plug is damaged.
–Liquid has penetrated the equipment.
–The equipment has been exposed to moisture.
–The equipment is malfunctioning, or does not operate according to the user
manual.
–The equipment has been dropped and damaged.
–The equipment show obvious signs of breakage.
15. Do not leave the equipment in an environment with a storage temperature of
below -20 °C (-4 °F) or above 60 °C (140 °F) as this may damage the compo-
nents. The equipment should be kept in a controlled environment.
16. CAUTION: Batteries are at risk of exploding if incorrectly replaced. Replace only
with the same or equivalent type as recommended by the manufacturer. Discard
used batteries according to the manufacturer’s instructions.
17. In accordance with IEC 704-1:1982 specifications, the sound pressure level at
the operator's position does not exceed 70 dB (A).
DISCLAIMER: These instructions are provided according to IEC 704-1 standards.
Advantech disclaims all responsibility for the accuracy of any statements contained
herein.
vii iDAQ-871_873 User Manual
Safety Precautions - Static Electricity
Follow these simple precautions to protect yourself from harm and the products from
damage.
To avoid electrical shock, always disconnect the power from the PC chassis
before manual handling. Do not touch any components on the CPU card or
other cards while the PC is powered on.
Disconnect the power before making any configuration changes. A sudden rush
of power after connecting a jumper or installing a card may damage sensitive
electronic components.
Précautions de sécurité – Électricité statique
Suivez ces précautions simples pour vous protéger des dangers et protéger les pro-
duits de dommage.
Pour éviter les chocs électriques, débranchez toujours l'alimentation du châssis
du PC avant toute manipulation manuelle. Ne touchez aucun composant de la
carte CPU ou d'autres cartes lorsque le PC est sous tension.
Coupez l'alimentation avant d'effectuer des modifications de configuration. Une
ruée soudaine de puissance après avoir connecté un cavalier ou installé une
carte peut endommager les capteurs sensibles composants electroniques.
iDAQ-871_873 User Manual viii
iDAQ-871_873 User Manual x
Figure 3.2 Ratiometric measurement ........................................ 15
3.1.2 Error Correction in Bridge Input Measurement ........................... 15
Figure 3.3 Voltage drop due to lead resistance......................... 16
Figure 3.4 Remote sensing ....................................................... 16
3.2 Strain Gauge Sensor Configurations ...................................................... 17
3.2.1 Quarter-Bridge Configuration...................................................... 17
Figure 3.5 Quarter-bridge configuration measuring axial and
bending strain........................................................... 17
3.2.2 Half Bridge Type I Configuration................................................. 18
Figure 3.6 Half-bridge type I configuration measuring axial and
bending strain........................................................... 18
3.2.3 Half Bridge Type II Configuration................................................ 19
Figure 3.7 Half-bridge type II configuration measuring axial and
bending strain........................................................... 19
3.2.4 Half Bridge Type III Configuration............................................... 20
Figure 3.8 Half-bridge type III configuration rejecting axial and
measuring bending strain ......................................... 20
3.2.5 Full Bridge Type I Configuration ................................................. 21
Figure 3.9 Full-bridge type I configuration rejecting axial and mea-
suring bending strain ................................................ 21
3.2.6 Full-Bridge Type II Configuration................................................ 22
Figure 3.10Full-bridge type II configuration rejecting axial and
measuring bending strain ......................................... 22
3.2.7 Full-Bridge Type III Configuration............................................... 23
Figure 3.11Full-bridge type III configuration rejecting bending and
measuring axial strain .............................................. 23
3.3 Force, Pressure, and Torque Sensor Configuration ............................... 24
3.4 Analog Input Methods ............................................................................. 25
3.4.1 Instant Analog Input Acquisition ................................................. 25
Figure 3.12Instant analog input acquisition................................ 25
3.4.2 Buffered Analog Input Acquisition............................................... 26
Figure 3.13Buffered analog input acquisition ............................. 26
Figure 3.14Start and stop of the analog input acquisition .......... 26
Figure 3.15Start and stop of the analog input acquisition with delay
27
3.5 Buffered Analog Input Configuration....................................................... 27
3.5.1 One-buffered Acquisition ............................................................ 27
Figure 3.16Post-trigger acquisition............................................. 27
Figure 3.17Post-trigger acquisition with delay............................ 28
Figure 3.18Pre-trigger acquisition .............................................. 28
Figure 3.19About-trigger acquisition........................................... 29
3.5.2 Streaming Analog Input Acquisition............................................ 29
Figure 3.20Streaming acquisition ............................................... 29
3.5.3 Retriggerable Analog Input Acquisition....................................... 30
Figure 3.21Post-trigger acquisition with retrigger ....................... 30
Figure 3.22Pre-trigger acquisition with retrigger......................... 30
Figure 3.23About-trigger acquisition with retrigger..................... 30
Figure 3.24Streaming acquisition with retrigger ......................... 31
3.6 Device Description and Configuration..................................................... 31
Figure 3.25Device Information of iDAQ-871............................... 31
Appendix A Specifications.................................... 33
A.1 Bridge Input............................................................................................. 34
Table A.1: Bridge Input specification of iDAQ-871 and iDAQ-873.
34
Table A.2: Filter type in different sampling rate setting.............. 34
Figure A.1 Frequency response of FIR filter under different sam-
pling rates................................................................. 35
xi iDAQ-871_873 User Manual
Figure A.2 Frequency response of SINC1 filter under different
sampling rates (16.66 SPS to 400 SPS) .................. 35
Figure A.3 Frequency response of SINC1 filter under different
sampling rates (1.2 kSPS to 7.2 kSPS).................... 35
Figure A.4 Frequency response of SINC5 filter under different
sampling rates .......................................................... 36
Table A.3: Accuracy................................................................... 36
Table A.4: Accuracy................................................................... 36
Table A.5: Idle Channel Noise ................................................... 36
A.2 Trigger..................................................................................................... 37
A.3 Power Consumption................................................................................ 37
Table A.6: Power Consumption ................................................. 37
A.4 General ................................................................................................... 37
A.5 Function Block......................................................................................... 38
Appendix B System Dimensions ..........................39
B.1 System Dimensions ................................................................................ 40
Figure B.1 System Dimensions - iDAQ-871............................... 40
Figure B.2 System Dimensions - iDAQ-873............................... 41
iDAQ-871_873 User Manual xii
iDAQ-871_873 User Manual 2
1.1 Overview
This chapter presents an overview of Advantech's industrial data acquisition (iDAQ)
modules, focusing on the iDAQ-871 and iDAQ-873 models, including their product
lineups, features, and accessories. Both iDAQ-871 and iDAQ-873 are 24-bit bridge
type acquisition modules. The iDAQ-871 is a 4-channel acquisition module that sup-
ports various bridge inputs (full, half, and quad bridges) and offers multiple resistance
and excitation voltages to accommodate different types of strain gauges. On the
other hand, the iDAQ-873 is an 8-channel acquisition module designed specifically
for quarter-bridge measurement. These modules are suitable for the precise mea-
surement of strain gauges, force sensors, load cells, and similar devices.
1.2 Product Overview
iDAQ-871
Figure 1.1 Overview of iDAQ-871
iDAQ-873
Figure 1.2 Overview of iDAQ-873
3 iDAQ-871_873 User Manual
Chapter 1 Start Using iDAQ-871/873
1.3 Product Features
1.3.1 Power Input
The power input of all the iDAQ I/O modules come from iDAQ chassis via the DB 15-
pin connector. The iDAQ I/O modules are powered on when the power of iDAQ chas-
sis is connected.
1.3.2 BoardID
A board ID (BID) can be assigned to the iDAQ chassis by the rotary switch and slot
number. The board ID will be shown in the software and can be used to distinguish
modules. The number shown around the rotary switch is in hexadecimal format. For
example, “A” represents 10 in decimal format, and “F” represents 15 in decimal for-
mat. The number assigned to each iDAQ module follows a rule combining the Chas-
sisID and slot number.
1.3.3 Plug and Play Device
The iDAQ modules are hot-swappable in the iDAQ chassis. The modules will be rec-
ognized instantly in the software (Installed Devices list) when they are plugged into
the iDAQ slots and they can be removed as soon as they are disabled in the soft-
ware. Therefore, it’s strongly recommended to operate these actions whilst the sys-
tem is in idle mode not data acquisition mode.
1.4 Driver Installation
The driver package could be found on Advantech Support Portal (https://www.advan-
tech.com/support). Search for iDAQ on the support portal, then the corresponding
driver/SDK package can be found. You’ll get the XNavi installer after the download
session finishes.
Execute the installer and it will guide you through the session. You can choose the
device and software components you’d like to install in the system (Figure 1.3). After
the selection, click on “start” to begin the installation.
Figure 1.3 XNavi Installation Interface
iDAQ-871_873 User Manual 4
1.5 Software Utility
Advantech offers device drivers, SDKs, third-party driver support and application
software to help fully exploit the functions of your iDAQ system. All these software
packages are available on the Advantech website: http://www.advantech.com/.
The Advantech Navigator is a utility that allows you to set up, configure and test your
device, and later store your settings in a proprietary database.
1. To set up the I/O device, you could first run the Advantech Navigator program
(by accessing Start/Programs/Advantech Automation/DAQNavi/Advantech Nav-
igator). The settings could also be saved.
2. You can then view the device(s) already installed on your system (if any) on the
Installed Device tree view. Once the software and hardware installation have
completed, you will see the iDAQ modules in the Installed Devices list.
1.6 Software Development Using DAQNavi SDK
DAQNavi SDK is the software development kit for programming applications with
Advantech DAQ products. The necessary runtime DLL, header files, software man-
ual and tutorial videos could be installed via XNavi installer. They could be found
under C:\Advantech\DAQNavi (default directory) after the finishing the installation.
1.7 FPGA Code Update
The FPGA could also be updated via the interface in Navigator. However, it isn’t nor-
mal to update an FPGA. Advantech strongly suggests you to consult your technical
support before considering an FPGA update.
1.8 Ordering Information
IDAQ-871-A 4-ch, 24-bit, 25.6kS/s/ch, 3-in-1 Bridge Input iDAQ Module
IDAQ-873-A 8-ch, 24-bit, 25.6kS/s/ch, Quarter Bridge Input iDAQ Module
1.9 Accessories
PCL-10137-1E DB-37 Shielded Cable, 1m
PCL-10137-2E DB-37 Shielded Cable, 2m
PCL-10137-3E DB-37 Shielded Cable, 3m
ADAM-3937-BE DB-37 Wiring Terminal, DIN-rail Mount
iDAQ-871_873 User Manual 6
2.1 Initial Unpacking Check
Before you install your iDAQ modules, please make sure you have the following nec-
essary components when unpacking the package:
DAQ module*1
Startup manual*1
If anything in the packing list is missing, please contact your local support for further
assistance.
2.2 Installation
Below are the steps to insert the iDAQ modules into the iDAQ chassis.
1. Insert the module follow the guide rail to the end
2. Screw the two thumb screws tight onto the chassis
Figure 2.1 iDAQ Module Install into iDAQ Chassis
7 iDAQ-871_873 User Manual
Chapter 2 Installation Guide
2.3 Signal Connection and Pin Assignment
The iDAQ-871 offers a choice of three bridge completion types based on the sensor
connected to the module, whereas the iDAQ-873 is specifically designed for quarter-
bridge applications. Details regarding field wiring connections and pin assignments
for each module are provided in the following section.
2.3.1 Quarter-Bridge Input Signal Connection
For quarter-bridge input, one of the four bridge arms serves as the external sensing
element, while the other three arms are completed by the device's internal resistors.
This setup is known as quarter-bridge completion. Figure 2.2 and Figure 2.3 illustrate
the 3-wire quarter-bridge input signal connection for iDAQ-871 and iDAQ-873,
respectively. To connect the strain gauge sensor (R B1), attach one end (1-wire side)
to the EX+ terminal (EX for iDAQ-873) and the other end (2-wire side) to both the
QTR/SC+ and AI+ terminals (QTR/SC and AI for iDAQ-873) using separate wires.
Additionally, connect the SC- terminal to the EX- terminal for shunt calibration (appli-
cable to iDAQ-871 only). Since remote sensing does not apply to quarter-bridge input
configuration, simply connect the RS+ and RS- terminals to the EX+ and EX- termi-
nals, respectively, on iDAQ-871. Note that the resistance of the quarter-bridge com-
pletion resistor RQB must match the nominal resistance of the strain gauge R B1.
Figure 2.2 3-wire quarter-bridge input signal connection for iDAQ-871
iDAQ-871_873 User Manual 8
Figure 2.3 3-wire quarter-bridge input signal connection for iDAQ-873
2-wire quarter-bridge input can also be used, as shown in Figure 2.4 and Figure 2.5.
One wire is used to connect both QTR/SC+ and AI+ terminals (QTR/SC and AI for
iDAQ-873). However, shunt calibration in this configuration will results in more error
due to imbalance of lead wire resistance (RLEAD).
Figure 2.4 2-wire quarter-bridge input signal connection for iDAQ-871
9 iDAQ-871_873 User Manual
Chapter 2 Installation Guide
Figure 2.5 2-wire quarter-bridge input signal connection for iDAQ-873
2.3.2 Half-Bridge Input Signal Connection
For half-bridge input, two of the four bridge arms are external sensing elements,
hence the name. The other two arms are provided, or completed, by device's internal
resistors. This configuration is also called half-bridge completion.
Figure 2.6 shows half-bridge input without remote sensing signal connection. Con-
nect one end of the strain gauge sensor (R B1) to EX+ terminal, and the other end
(RB2) to both EX- and SC- terminals using different wires. In addition, connect the
middle node (junction of RB1 and RB2) of the strain gauge sensor to both AI+ and
QTR/SC+ terminals using different wires. Since remote sensing is not used in this
configuration, simply connect RS+ and RS- terminals to EX+ and EX- terminals,
respectively.
Figure 2.6 Half-bridge input without remote sensing signal connection
iDAQ-871_873 User Manual 10
If remote sensing is required, connect the RS+ terminal to one end of the strain
gauge (RB1) by an independent wire, and connect the RS- terminal to the other end
(RB2) by another independent wire, as shown in Figure 2.7 Do not share the same
wire for RS and EX terminals.
Figure 2.7 Half-bridge input with remote sensing signal connection
2.3.3 Full-Bridge Input Signal Connection
For full-bridge input, all four bridge arms are external sensing elements, hence the
name. This configuration is also called full-bridge completion.
Figure 2.8 shows full-bridge input without remote sensing signal connection. Connect
middle node of the two left arms (junction of RB1 and RB2) to both AI+ and QTR/SC+
terminals using different wires, and middle node of the two right arms (junction of R B4
and RB3) to AI- terminal. Connect the middle node of the two upper arms (junction of
RB1 and RB4) to EX+ terminal, and the middle node of the two lower arms (junction of
RB2 and RB3) to both EX- and SC- terminals using different wires. Since remote
sensing is not used in this configuration, simply connect RS+ and RS- terminals to
EX+ and EX- terminals, respectively.
Figure 2.8 Full-bridge input without remote sensing signal connection
11 iDAQ-871_873 User Manual
Chapter 2 Installation Guide
If remote sensing is required, connect RS+ terminal to the middle point of the two
upper arms (RB1 and RB4) by an independent wire, and connect the RS- terminal to
the middle point of the two lower arms (RB2 and RB3) by another independent wire,
as shown in Figure 2.9. Do not share the same wire for RS and EX terminals.
Figure 2.9 Full-bridge input with remote sensing signal connection
2.3.4 Pin Assignment
iDAQ-871
Figure 2.10 Pin Assignment Diagram of iDAQ-871
iDAQ-871_873 User Manual 12
iDAQ-873
Figure 2.11 Pin Assignment Diagram of iDAQ-873
Table 2.1: Pin Assignment Diagram of iDAQ-871
Pin Name Pin Number Description
RS<0..3>+ 3, 8, 13, 18 Remote sensing positive terminal.
RS<0..3>- 4, 9, 14, 19 Remote sensing negative terminal.
EX<0..3>+ 23, 27, 33, 37 Excitation voltage positive terminal.
EX<0..3>- 20, 24, 30, 34 Excitation voltage negative terminal.
AI<0..3>+ 22, 26, 32, 36 Analog input positive terminal.
AI<0..3>- 21, 25, 31, 35 Analog input negative terminal.
QTR/SC<0..3>+ 2, 7, 12, 17 Quarter bridge completion/shunt calibration
positive terminal.
SC<0..3>- 1, 6, 11, 16 Shunt calibration negative terminal.
NC 5, 10, 15, 28, 29 Not connected.
Table 2.2: Pin Assignment Diagram of iDAQ-873
Pin Name Pin Number Description
QTR/
SC<0…7> 18, 13, 27, 22, 34, 29, 6, 1 Quarter bridge completion/shunt calibration ter-
minal of AI
EXn<0…7> 19, 14, 28, 23, 35, 30, 7, 2 Excitation voltage terminal of AI
AI<0…7> 37, 32, 9, 4, 16, 11, 25, 20 Terminal of analog input channel
NC 3, 5, 8, 10, 12, 15, 17, 21,
24,26, 31, 33, 36 No Connection
Chapter 3
3Function Details
15 iDAQ-871_873 User Manual
Chapter 3 Function Details
Figure 3.2 Ratiometric measurement
3.1.2 Error Correction in Bridge Input Measurement
Field wiring is used to connect sensors to measurement devices that have a non-
zero resistance, and resistance of each bridge arm also has errors. These undesired
factors create errors in bridge input measurement. The device provides mechanisms
to correct the errors: remote sensing, offset nulling, and shunt calibration.
3.1.2.1 Remote Sensing
Remote sensing corrects for errors due to resistance of excitation voltage leads. It is
useful in applications that employ long or small wires to connect the sensors to the
measuring device, as the wires have high resistance.
As shown in Figure 3.3, current generated by excitation voltage source will flow
through the positive terminal of the source, the bridge, to the negative terminal of the
source (indicated by red lines). The wire resistance (R LEAD) that connects both posi-
tive terminal and negative terminal of the source to the bridge causes voltage drops
(VLEAD), which results in a smaller voltage across the bridge compared to the actual
excitation voltage generated by the source. This voltage difference leads to gain
reduction in the measured result.
iDAQ-871_873 User Manual 16
Figure 3.3 Voltage drop due to lead resistance
As shown in Figure 3.4, instead of using excitation voltage source output as the volt-
age reference of the ADC, in remote sensing, two additional wires (indicated by
green lines) that connect to the bridge directly measure the voltage across the
bridge, and use this value as the voltage reference of the ADC. Because both lines
are high impedance input terminals, there is no current flowing through, and therefore
no voltage drops on these wires.
Figure 3.4 Remote sensing
Remote sensing is not applicable for quarter-bridge configuration due to the imbal-
ance architecture (only RB1 has wire resistance).
17 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.1.2.2 Offset Nulling
In fact, output of the bridge may not be 0 V even when not loaded. This is because
slight variations in resistance among the bridge arms generate nonzero offset volt-
age. Offset nulling performs software compensation for this offset voltage.
The software will first measure the bridge output when not loaded and stored it as an
initial value. Then this initial value will be subtracted from the reading before scaling
when measuring under load.
3.1.2.3 Shunt Calibration
In shunt calibration, load is simulated by shunting a shunt calibration resistor (R SC)
inside the device to RB2 of the bridge, which results in equivalent resistance change
on that arm. A switch inside the device controls whether to connect R SC or not.
Because values of all resistors are known, and the resistance change on the shunt-
ing arm is also known, the theoretical value of this simulated load can therefore be
calculated. Then the bridge output when shunting is measured, and the ratio between
the theoretical value and the measured value is stored and used when scaling the
reading.
3.2 Strain Gauge Sensor Configurations
This section describes the supported strain gauge sensor configurations.
3.2.1 Quarter-Bridge Configuration
This section provides information for the quarter-bridge strain gauge sensor configu-
ration. This configuration measures either axial or bending strain. Figure 3.5 shows
how to position the strain gauge sensor in both axial and bending configurations.
Refer to 2.3.1 Quarter-Bridge Input Signal Connection for detailed signal wiring of
this configuration.
Figure 3.5 Quarter-bridge configuration measuring axial and bending strain
The quarter-bridge configuration has the following characteristics:
A single active strain gauge sensor RB1 is mounted in the principal direction of
axial or bending strain.
Sensitive to both axial and bending strain.
A quarter-bridge completion resistor R QB and two half-bridge completion resis-
tors RHB are required. They are provided by the device.
Both a shunt calibration resistor RSC and a switch are provided by the device.
Sensitivity ≈ 0.5 μV/V per με, for GF = 2.0.
19 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.2.3 Half Bridge Type II Configuration
This section provides information for the half-bridge type II strain gauge sensor con-
figuration. This configuration measures either axial or bending strain. Figure 3.7
shows how to position the strain gauge sensors in both axial and bending configura-
tions. Refer to 2.3.2 Half-Bridge Input Signal Connection for detailed signal wiring of
this configuration.
Figure 3.7 Half-bridge type II configuration measuring axial and bending strain
The half-bridge type II configuration has the following characteristics:
There are two active strain gauge sensors R B1 and RB2. RB1 measures the
strain and is mounted in the principal direction of axial or bending strain. R B2
acts as a Poisson gauge and is perpendicular to the principal axis of strain.
Sensitive to both axial and bending strain.
Two half-bridge completion resistor RHB are required. They are provided by the
device.
Both a shunt calibration resistor RSC and a switch are provided by the device.
Sensitivity ≈ 0.65 μV/V per με, for GF = 2.0.
Strain value can be calculated by the following equation:
where GF is the gauge factor of the strain gauge sensor provided by the sensor man-
ufacturer, ν is the Poisson’s ratio, defined as the negative ratio of transverse strain to
axial (longitudinal) strain. Poisson’s ratio is a material property of the specimen being
measured, and Vr is the ratiometric bridge output value measured by the ADC
Shunt calibration can be used to compensate for errors due to lead resistance.
strain
4
V
r
–
GF
1
v
+ 2
V vr
1– –
------------------------------------------------------------------=
V
r
V strainedA I
V unstrainedAI
–
VE X
---------------------------------------------------------------------------------------=
21 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.2.5 Full Bridge Type I Configuration
This section provides information for the full-bridge type I strain gauge sensor config-
uration. This configuration only measures bending strain. Figure 3.9 shows how to
position the strain gauge sensors in bending configuration. Refer to 2.3.3 Full-Bridge
Input Signal Connection for detailed signal wiring of this configuration.
Figure 3.9 Full-bridge type I configuration rejecting axial and measuring
bending strain
The full-bridge type I configuration has the following characteristics:
There are four active strain gauge sensors R B1, RB2, RB3, and RB4. RB1 and
RB3 are mounted in the principal direction of bending strain on one side of the
strain specimen (top) while RB2 and RB4 are mounted in the principal direction
of bending strain on the opposite side (bottom).
Highly sensitive to bending strain and rejects axial strain.
Both a shunt calibration resistor RSC and a switch are provided by the device.
Sensitivity ≈ 2 μV/V per με, for GF = 2.0.
Strain value can be calculated by the following equation:
where GF is the gauge factor of the strain gauge sensor provided by the sensor man-
ufacturer, and Vr is the ratiometric bridge output value measured by the ADC
Shunt calibration can be used to compensate for errors due to lead resistance.
str ain
V
–
r
GF
---------=
V
r
V str ainedAI
V uns trainedAI
–
VEX
---------------------------------------------------------------------------------------=
iDAQ-871_873 User Manual 22
3.2.6 Full-Bridge Type II Configuration
This section provides information for the full-bridge type II strain gauge sensor config-
uration. This configuration only measures bending strain. Figure 3.10 shows how to
position the strain gauge sensors in bending configuration. Refer to 2.3.3 Full-Bridge
Input Signal Connection for detailed signal wiring of this configuration.
Figure 3.10 Full-bridge type II configuration rejecting axial and measuring
bending strain
The full-bridge type II configuration has the following characteristics:
There are four active strain gauge sensors R B1, RB2, RB3, and RB4. RB1 and
RB2 are mounted in the principal direction of bending strain with R B1 on one side
of the strain specimen (top) while RB2 on the opposite side (bottom). RB3 and
RB4 act together as Poisson gauge and are mounted transverse (perpendicular)
to the principal direction of bending strain with RB4 on one side of the strain
specimen (top) and RB3 on the opposite side (bottom).
Sensitive to bending strain and rejects axial strain.
Both a shunt calibration resistor RSC and a switch are provided by the device.
Sensitivity ≈ 1.3 μV/V per με, for GF = 2.0.
Strain value can be calculated by the following equation:
where GF is the gauge factor of the strain gauge sensor provided by the sensor man-
ufacturer, ν is the Poisson’s ratio, defined as the negative ratio of transverse strain to
axial (longitudinal) strain. Poisson’s ratio is a material property of the specimen being
measured, and Vr is the ratiometric bridge output value measured by the ADC
Shunt calibration can be used to compensate for errors due to lead resistance.
strain
2
–
Vr
GF
1 v+
----------------------------=
V
r
V strainedAI
V unstrainedAI
–
VE X
---------------------------------------------------------------------------------------=
23 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.2.7 Full-Bridge Type III Configuration
This section provides information for the full-bridge type III strain gauge sensor con-
figuration. This configuration only measures axial strain. Figure 3.11 shows how to
position the strain gauge sensors in axial configuration. Refer to 2.3.3 Full-Bridge
Input Signal Connection for detailed signal wiring of this configuration.
Figure 3.11 Full-bridge type III configuration rejecting bending and measuring
axial strain
The full-bridge type III configuration has the following characteristics:
There are four active strain gauge sensors R B1, RB2, RB3, and RB4. RB1 and
RB3 are mounted in the principal direction of bending strain with R B3 on one side
of the strain specimen (top) while RB1 on the opposite side (bottom). RB2 and
RB4 act together as Poisson gauge and are mounted transverse (perpendicular)
to the principal direction of bending strain with R B4 on one side of the strain
specimen (top) and RB2 on the opposite side (bottom).
Sensitive to axial strain and rejects bending strain.
Both a shunt calibration resistor RSC and a switch are provided by the device.
Sensitivity ≈ 1.3 μV/V per με, for GF = 2.0.
Strain value can be calculated by the following equation:
where GF is the gauge factor of the strain gauge sensor provided by the sensor man-
ufacturer, ν is the Poisson’s ratio, defined as the negative ratio of transverse strain to
axial (longitudinal) strain. Poisson’s ratio is a material property of the specimen being
measured, and Vr is the ratiometric bridge output value measured by the ADC
Shunt calibration can be used to compensate for errors due to lead resistance.
strain
2
V
r
–
GF
v 1+
V vr
1– –
--------------------------------------------------------------=
V
r
V strainedA I
V unstrainedAI
–
VE X
---------------------------------------------------------------------------------------=
iDAQ-871_873 User Manual 24
3.3 Force, Pressure, and Torque Sensor
Configuration
The device can be used with force sensors (such as load cells), pressure sensors, or
torque sensor that have the following characteristics:
Wheatstone bridge based.
Unamplified mV/V or V/V output.
These sensors typically use a full-bridge configuration with a 350Ω nominal bridge
resistance, but other configurations and nominal bridge resistances also can be
used. Refer to 2.3.3 Full-Bridge Input Signal Connection for detailed signal wiring of
this configuration.
In Advantech DAQNavi, linear scaling for bridge-based force, pressure, and torque
sensors is based on two points which are specified as pairs of corresponding physi-
cal and electrical values: “EV1, PV1”, and “EV2, PV2”. These should be based on the
calibration certificate of the sensor, if one is available; otherwise, they can be based
on the specifications or datasheet of the sensor. Any two points can be used assum-
ing that they are far enough apart to accurately determine the slop of the linear scal-
ing equation. For example:
PV1: The zero point of the sensor. Zero force, zero pressure, or zero torque.
EV1: The electrical output (ratiometric bridge output) corresponding to the zero
point of the sensor, in mV/V or V/V.
PV2: The maximum physical reading of the sensor, or capacity. Maximum load,
maximum pressure, or maximum torque.
EV2: The electrical output (ratiometric bridge output) corresponding to the maxi-
mum physical reading of the sensor, in mV/V or V/V.
The two-point linear conversion uses the following equations:
where Vr is the ratiometric bridge output value measured by the ADC.
Note! Some sensor calibration certificates specify the electrical output in mV
or V, not mV/V or V/V. If this is the case, divide the specified electrical
output by the excitation voltage at which the calibration was performed.
mPV
1
PV
2
–
EV
1
EV
2
–
--------------------------=
b PV m EV1 1
–
=
Physical reading m V
r
b+
=
25 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.4 Analog Input Methods
3.4.1 Instant Analog Input Acquisition
With instant analog input acquisition, the software controls the sample timing. The
analog-to-digital converter (ADC) is continuously converting analog input signals by
its maximum allowable conversion rate. Each time the software sends a “read instant
analog input sample” command, the most recent conversion result is sampled as
shown in Figure 3.12.
Figure 3.12 Instant analog input acquisition
The advantage of instant acquisition is low latency. It is typically used for reading a
single sample of analog input.
iDAQ-871_873 User Manual 26
3.4.2 Buffered Analog Input Acquisition
With buffered analog input acquisition, the ADC conversion rate and the duration of
the acquisition is controlled by hardware timing signals. All conversion results are
sampled and stored in the buffer memory before sending back to the host computer
as shown in Figure 3.13.
Figure 3.13 Buffered analog input acquisition
The start and stop of the acquisition are controlled by the start trigger and stop trig-
ger, respectively. When configuration is completed, the acquisition engine of the
iDAQ chassis is at standby state. After receiving a start trigger, acquisition becomes
active and each rising edge of the sample clock acquires one analog input sample.
The acquisition active period lasts until a stop trigger is received, which ends the
acquisition. This is shown in Figure 3.14.
Figure 3.14 Start and stop of the analog input acquisition
27 iDAQ-871_873 User Manual
Chapter 3 Function Details
The start and stop of acquisition can also be delayed in number of samples after
receiving the corresponding trigger signal. As shown in Figure 3.15, the start of
acquisition is delayed by 3 samples after receiving a start trigger, and the stop of
acquisition is delayed by 2 samples after receiving a stop trigger.
Figure 3.15 Start and stop of the analog input acquisition with delay
Buffered analog input acquisition has several advantages over instant analog input
acquisition:
The start and stop time of acquisition (or duration of the acquisition) can be pre-
cisely controlled by hardware trigger signals.
ADC conversion rate is configurable, and sample rate can be much higher by
using hardware sample clock signal.
Time between samples is deterministic.
3.5 Buffered Analog Input Configuration
3.5.1 One-buffered Acquisition
For one-buffered acquisition, only a specified number of samples is acquired. The
start or stop of acquisition can be controlled by a software command or a hardware
signal. Three types of acquisitions can be achieved: post-trigger acquisition, pre-trig-
ger acquisition, and about-trigger acquisition.
3.5.1.1 Post-Trigger Acquisition
A post-trigger acquisition acquires a specified number of samples after the start trig-
ger. The acquisition starts when a start trigger is received and automatically stops
when the specified number of samples is acquired. An example of 5-sample post-trig-
ger acquisition is shown in Figure 3.16.
Figure 3.16 Post-trigger acquisition
iDAQ-871_873 User Manual 28
The start trigger can be a software command or a hardware signal. If a hardware sig-
nal is used as the start trigger, the start of acquisition can be delayed for a specified
number of sample clock cycles after a start trigger is received. Figure 3.17 shows an
example of a 2-sample delay post-trigger acquisition. Refer to the device specifica-
tions for possible signal sources.
Figure 3.17 Post-trigger acquisition with delay
3.5.1.2 Pre-Trigger Acquisition
A pre-trigger acquisition acquires a specified number of samples before the stop trig-
ger. The acquisition is started by a software command and stopped when a hardware
stop trigger is received. Figure 3.18 shows an example of a 5-sample pre-trigger
acquisition. Only the samples in the shaded area are returned.
Figure 3.18 Pre-trigger acquisition
The stop trigger can only be a hardware signal. Refer to the device specifications for
possible signal sources.
29 iDAQ-871_873 User Manual
Chapter 3 Function Details
3.5.1.3 About-Trigger Acquisition
An about-trigger acquisition is the same as a pre-trigger acquisition except that the
time when the acquisition stops can be delayed by a specified number of sample
clock cycles. Figure 3.19 shows an example of a 5-sample about-trigger acquisition
with 2 cycles of stop delay. Only the samples in the shaded area are returned.
Figure 3.19 About-trigger acquisition
The stop trigger can only be a hardware signal. Refer to the device specifications for
possible signal sources.
3.5.2 Streaming Analog Input Acquisition
For a streaming acquisition, the number of samples to be acquired is set to infinite.
The acquisition starts when a start trigger is received and continues until a stop trig-
ger is received as shown in Figure 3.20.
Figure 3.20 Streaming acquisition
Both the start trigger and the stop trigger can come from a software command or a
hardware signal. If a hardware signal is used, the start (for the start trigger) or the
stop (for the stop trigger) of the acquisition can also be delayed. Refer to the device
specifications for possible signal sources.
iDAQ-871_873 User Manual 30
3.5.3 Retriggerable Analog Input Acquisition
The acquisition can be re-triggerable. When re-trigger is enabled, after the acquisi-
tion stops, it restarts whenever the required trigger is received, and reconfiguration of
the acquisition is not required.
Figures 3.21 to 3.24 show examples of retrigger acquisition for post-trigger, pre-trig-
ger, about-trigger, and streaming acquisitions, respectively. In a post-trigger acquisi-
tion, a start trigger is ignored while the acquisition is in progress. In an about-trigger
acquisition, a stop trigger is ignored while the acquisition is being stopped.
Figure 3.21 Post-trigger acquisition with retrigger
Figure 3.22 Pre-trigger acquisition with retrigger
Figure 3.23 About-trigger acquisition with retrigger
31 iDAQ-871_873 User Manual
Chapter 3 Function Details
Figure 3.24 Streaming acquisition with retrigger
3.6 Device Description and Configuration
The Device Description is used to differentiate the modules in the iDAQ system. It's
given following a naming rule of combining chassis ID, model name and slot number.
You can change the description in Navigator, or just leave it as default. The descrip-
tion is used in your own program, in order to get control or device handler from the
device.
Figure 3.25 Device Information of iDAQ-871
iDAQ-871_873 User Manual 32
Appendix A
ASpecifications
iDAQ-871_873 User Manual 34
A.1 Bridge Input
Digital low-pass filter
–Filter type: FIR or SINC1, selected by sampling rate. Refer to Table A2 for
detailed information
-3 dB bandwidth: Configured along with sampling rate. Refer to Figure A1~A4
for detailed frequency response for each filters under different sampling rate set-
tings.
Table A.1: Bridge Input specification of iDAQ-871 and iDAQ-873
Item iDAQ-871 iDAQ-873
ADC Resolution 24-bit
Channels 4 8
Input Range
±1 V/V, ±500 mV/V, ±250 mV/V, ±125 mV/V,
±62.5 mV/V, ±31.25 mV/V, ±15.63 mV/V, or ±7.81 mV/V
Auto configured by software according to physical input range
settings
Bridge Mode Full, half, quarter Quarter
Bridge Resistance 120 Ω, 350 Ω, 1 kΩ 120 Ω
Shunt Calibration 100 kΩ 100 kΩ
Excitation Voltage 2.5V, 5V 2V
Table A.2: Filter type in different sampling rate setting
Sampling Rate (SPS) -3-dB Bandwidth (Hz) Filter Type
2.5 1.2 FIR
5 2.4 FIR
10 4.7 FIR
16.6 7.38 SINC1
20 13 FIR
50 22.1 SINC1
60 26.6 SINC1
100 44.3 SINC1
400 177 SINC1
1200 525 SINC1
2400 1015 SINC1
4800 1798 SINC1
7200 2310 SINC1
14400 2940 SINC5
19200 3920 SINC5
25600 5227 SINC5
Produktspecifikationer
| Varumärke: | Advantech |
| Kategori: | Inte kategoriserad |
| Modell: | IDAQ-873-A |
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