Using DAQ Devices in LabVIEW
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Transcript of Using DAQ Devices in LabVIEW
Telemark University College
Department of Electrical Engineering, Information Technology and Cybernetics
Faculty of Technology, Postboks 203, Kjølnes ring 56, N-3901 Porsgrunn, Norway. Tel: +47 35 57 50 00 Fax: +47 35 57 54 01
Using DAQ devices in LabVIEW
HANS-PETTER HALVORSEN, 2011.01.04
ii
PREFACE
In this lab you will learn basic Data Acquisition (DAQ) and how to use a DAQ unit in LabVIEW. We will use the
USB-6008 DAQ device from National Instruments. NI USB-6008 is a simple and low-cost USV based
multifunction I/O device from National Instruments. The device is well suited for training and education
purpose.
The purpose of data acquisition is to measure an electrical or physical phenomenon such as voltage, current,
temperature, pressure, or sound. PC-based data acquisition uses a combination of hardware, software, and a
computer to take measurements.
The principle of Data Acquisition:
USB-6008 DAQ device from National Instruments:
iii
TABLE OF CONTENTS
Preface ..................................................................................................................................................................... ii
Table of Contents .................................................................................................................................................... iii
1 Introduction to Data Acquisition ....................................................................................................................4
2 Measurement and Automation Explorer (MAX) ............................................................................................8
3 Using the DAQ Assistant ...............................................................................................................................10
4
1 INTRODUCTION TO DATA ACQUISITION
In this task we will learn basic Data Acquisition in LabVIEW. We will use the USB-6008 DAQ device.
Background information for this task is described in detailed in the Tutorial “Data Acquisition in
LabVIEW”. The Tutorial consists of a pdf document, videos, example code, additional resources and web links.
http://home.hit.no/~hansha/?tutorial=daq
The purpose of data acquisition is to measure an electrical or physical phenomenon such as voltage, current,
temperature, pressure, or sound. PC-based data acquisition uses a combination of modular hardware,
application software, and a computer to take measurements. While each data acquisition system is defined by
its application requirements, every system shares a common goal of acquiring, analyzing, and presenting
information. Data acquisition systems incorporate signals, sensors, actuators, signal conditioning, data
acquisition devices, and application software.
So summing up, Data Acquisition is the process of:
Acquiring signals from real-world phenomena
Digitizing the signals
Analyzing, presenting and saving the data
5 Introduction to Data Acquisition
Lab Work: Using DAQ devices in LabVIEW
The DAQ system has the following parts involved, see Figure:
The parts are:
Physical input/output signals
DAQ device/hardware
Driver software
Your software application (Application software)
In LabVIEW, the NI-DAQmx Driver software is the layer of software for easily communicating with the
hardware. It forms the middle layer between the application software and the hardware. Driver software also
prevents a programmer from having to do register-level programming or complicated commands in order to
access the hardware functions.
Below we see the DAQmx palette in LabVIEW:
The DAQ Assistant, included with NI-DAQmx, is a graphical, interactive guide for configuring, testing, and
acquiring measurement data. With a single click, you can even generate code based on your configuration,
making it easier and faster to develop complex operations. Because DAQ Assistant is completely menu-driven,
6 Introduction to Data Acquisition
Lab Work: Using DAQ devices in LabVIEW
you will make fewer programming errors and drastically decrease the time from setting up your DAQ system to
taking your first measurement.
NI USB-6008 is a simple and low-cost multifunction I/O device from National Instruments.
The device has the following specifications:
8 analog inputs (12-bit, 10 kS/s)
2 analog outputs (12-bit, 150 S/s)
12 digital I/O
USB connection, No extra power-supply neeeded
Compatible with LabVIEW, LabWindows/CVI, and Measurement Studio for Visual Studio .NET
NI-DAQmx driver software
The NI USB-6008 is well suited for education purposes due to its small size and easy USB connection.
Measurement & Automation Explorer (MAX) provides access to your National Instruments devices and
systems.
With MAX, you can:
Configure your National Instruments hardware and software
Create and edit channels, tasks, interfaces, scales, and virtual instruments
Execute system diagnostics
View devices and instruments connected to your system
Update your National Instruments software
In addition to the standard tools, MAX can expose item-specific tools you can use to configure, diagnose, or
test your system, depending on which NI products you install. As you navigate through MAX, the contents of
the application menu and toolbar change to reflect these new tools.
7 Introduction to Data Acquisition
Lab Work: Using DAQ devices in LabVIEW
8
2 MEASUREMENT AND AUTOMATION EXPLORER (MAX)
Measurement & Automation Explorer (MAX) provides access to your National Instruments devices and
systems.
With MAX, you can:
Configure your National Instruments hardware and software
Create and edit channels, tasks, interfaces, scales, and virtual instruments
Execute system diagnostics
View devices and instruments connected to your system
Update your National Instruments software
Task 1: MAX
Connect you USB-6008 Device and open the Measurement and Automation Explorer (MAX). See if you can
find you DAQ device in MAX and make sure it works properly. Run a “Self Test” and open the “Test Panels” in
order to test your device.
Perform a so-called Loopback test.
9 Measurement and Automation Explorer (MAX)
Lab Work: Using DAQ devices in LabVIEW
Use a multi-meter to check if the voltage levels on the output and input channels are correct according to your
settings.
[End of Task]
10
3 USING THE DAQ ASSISTANT
Note! Read the “USB-6008 DAQ device” Lab Equipment document before you start!
The document and additional information is available from: http://home.hit.no/~hansha/?equipment=usb6008
Connect your USB-6008 DAQ device to your computer and make sure it works. Use the Measurement and
Automation Explorer (MAX) to configure and test your device. Use also a Volt meter to check that the voltage is
correct.
Measurement and Automation Explorer (MAX):
The Data Acquisition palette in LabVIEW:
DAQ Assistant:
The DAQ Assistant, included with NI-DAQmx, is a graphical, interactive guide for configuring, testing, and
acquiring measurement data. With a single click, you can even generate code based on your configuration,
making it easier and faster to develop complex operations.
The NI-DAQmx Driver software is the layer of software for easily communicating with the hardware. It forms
the middle layer between the application software and the hardware.
11 Using the DAQ Assistant
Lab Work: Using DAQ devices in LabVIEW
Task 2: Analog Output
Create a program in LabVIEW that write analog values from the USB-6008 DAQ device. Use the DAQ Assistant.
The program should include a While loop that continuously write values from the USB-6008 DAQ device.
Example:
The DAQ Assistant Properties should look something like this:
12 Using the DAQ Assistant
Lab Work: Using DAQ devices in LabVIEW
Use an ordinary “Numeric Control” on the Front Panel in order to write data between 0 and 5 [V] to the DAQ
device.
Write different values between 0 and 5 [V] and use a multi-meter in order to check if the program works as
expected.
[End of Task]
Task 3: Analog Input
Create a program in LabVIEW that read analog values from the USB-6008 DAQ device. Use the DAQ Assistant.
The program should include a While loop that continuously reads values from the USB-6008 DAQ device.
Example:
The DAQ Assistant Properties should look something like this:
13 Using the DAQ Assistant
Lab Work: Using DAQ devices in LabVIEW
Run the “Analog Output.vi” and the “Analog Input.vi” in parallel in order to check that the program works as
expected. See the example below.
[End of Task]
Task 4: Combined Analog In and Analog Out
Create a new program where you connect the Analog Input and Analog Output programs together in one
program.
Specifications for the application:
Put the Analog Input and Analog Output code into different SubVIs.
14 Using the DAQ Assistant
Lab Work: Using DAQ devices in LabVIEW
Do some calculations on the input signal and send the calculated result to the analog output. Put the
calculation code into a SubVI.
Plot the different values on the screen.
Use the Project Explorer in LabVIEW for your application.
Create an Executable File (.exe) of your Application.
In order to use the Project Explorer, you will have to create an “Empty Project”:
Below we see an example of the Project Explorer:
Below we see how we can use the Project Explorer to create an .exe (executable) file:
15 Using the DAQ Assistant
Lab Work: Using DAQ devices in LabVIEW
[End of Task]
Telemark University College
Faculty of Technology
Kjølnes Ring 56
N-3914 Porsgrunn, Norway
www.hit.no
Hans-Petter Halvorsen, M.Sc.
Telemark University College
Department of Electrical Engineering, Information Technology and Cybernetics
Phone: +47 3557 5158
E-mail: [email protected]
Blog: http://home.hit.no/~hansha/
Room: B-237a