Transcript Unit 1 PowerPoint Slides

EET 2259
Programming for
Electronics Technology
Professor Nick Reeder
Reminders

Please turn off cell phones.

No food or soft drinks in the classroom.

Stow water bottles at floor level.
EET 2259 Unit 1
LabVIEW Basics

Read Bishop, Chapter 1.

Lab #1 and Homework #1 due next
week.
LabVIEW
Stands for Laboratory Virtual
Instrument Engineering Workbench.
 It’s a software package created by
National Instruments (www.ni.com).
This company bought Multisim a few
years ago.

(Bishop, p. 3)
National Instruments
Company founded in 1976 in Austin,
TX.
 In addition to Multisim, LabVIEW, and
other software packages, they sell
data acquisition boards and other
hardware for using computers in
engineering, science, and industry.

(Bishop, pp. 3-4)
Some of LabVIEW’s Uses
General-purpose programming
 Instrument control
 Data acquisition
 Data analysis
 Data presentation
 Automated testing

General-purpose Programming

Writing programs to perform
calculations, process information, play
games, etc. Examples:
Checkbook balancer
 Calorie counter
 Baseball statistics calculator


This is not really what LabVIEW is
meant for, but you can use it to do these
things.
Instrument Control

Using the computer to control
multimeters, oscilloscopes, function
generators, etc.
Data Acquisition (DAQ)


Connecting the computer directly to circuits or
sensors to measure voltage, current, temperature,
pressure, light intensity, chemical composition, etc.
Need to have either:

a special data-acquisition board
installed in your computer,

or an external data-acquisition
device such as an NI myDAQ.
Data Analysis
Performing statistical analysis, curve
fitting, signal processing, or other
kinds of mathematical calculations on
the data that you’ve gathered from a
DAQ board or from measuring
instruments.
 Similar to what you can do with
Microsoft Excel or other spreadsheet
programs.

Data Presentation
Using tables, charts, and graphs to
present the results of your data
analysis.
 Again, similar to what you can do
with Microsoft Excel or other
spreadsheet programs.

Automated Testing

Using computers to automatically test
circuit boards or other manufactured
parts as they leave an assembly line.
G
LabVIEW is built around a
programming language called G.
 Most of this course will be devoted to
learning how to write programs in G.

(Bishop, p. 4)
Graphical vs. Text-Based
Language
Most other programming languages
(Assembly, VisualBasic, C, C++,
Java, Python, etc.) are text-based
languages. You write programs by
typing text.
 G is a graphical language. You write
programs by placing icons and
connecting them with wires.
(Bishop, p. 4)

Example Program in C
#include <stdio.h>
int main()
{
float value1, value2, product;
printf("Enter first number => ");
scanf("%f", &value1);
printf("Enter second number => ");
scanf("%f", &value2);
product = value1 * value2;
printf("The product is %f", product);
}
The Same Program in LabVIEW
“Virtual Instruments”
LabVIEW programs are called virtual
instruments, or VIs for short.
 When you save a program file in
LabVIEW, its extension is “.vi”

(Bishop, p. 4)
Front Panel & Block Diagram
Every LabVIEW program has two
parts, which appear in two different
windows on your computer screen:
the front panel and the block
diagram.
 You don’t have to save these two
parts separately; whenever you save,
they’re both saved in the same file.

Front Panel

The front panel is the user interface
for a program. It contains controls
(inputs) and indicators (outputs).
Controls let the user feed data into the
program.
 Indicators let the program give results
back to the user.

Sample Front Panel
Block Diagram
The block diagram shows the
program’s underlying logic. It shows
how the user’s data (entered through
controls) is manipulated to give the
results that are fed back to the user
(through indicators).
 The block diagram contains
components “wired” together.

Sample Block Diagram
Toolbar
Run Button
Continuous Run Button
Abort Execution
Additional Buttons on
the Diagram Toolbar
Pause/Continue Button
Execution Highlighting
Button
Text Settings
Step Into Button
Align Objects
Step Over Button
Distribute Objects
Step Out Button
Reorder
Resize front panel
objects
(Bishop, pp. 10-14)
Controls Palette & Functions Palette
Controls Palette
(Used to place controls &
indicators on Front Panel)
Functions Palette
(Used to place functions
on Block Diagram)
(Bishop, pp. 24-26)
Menus


LabVIEW has pull-down menus and
short-cut menus (pop-up menus) that
give you many options.
Sections 1.6 and 1.7 in textbook discuss
the menus.
(Bishop, pp. 14-23)
Help


LabVIEW’s context help window is very
useful. It automatically shows help for
functions and other objects when you roll
your mouse over those objects.
More detailed help is also available
through Help menu.
(Bishop, pp. 33-34)
Context Help Window

Ctrl + H

Detailed help
Lock help
Simple/Complex Diagram help


Saving Your Control Values



When you save a VI, values that you
have set on the front panel are not
saved.
But you can cause them to be saved by
selecting Edit > Make Current Values
Default before you save the VI.
Or you can do this with a single control by
right-clicking it and selecting Data
Operations > Make Current Value
Default.
Example Programs



LabVIEW comes with many example VIs,
which you can access by clicking Help >
Find Examples… in LabVIEW’s menus.
More examples are in the textbook’s
Learning Directory files, which you’ll
download from the Web as part of
Homework #1.
Studying examples is a great way to
learn any programming language.
(Bishop, p. 5)
PCI-6221 or myDAQ?

Recall that for programs that make measurements,
we have two hardware choices:

The PCI-6221 card that is
installed in your computer.

Or the myDAQ that plugs into a
USB port.

You make this choice inside
the DAQ Assistant, which you
place on a VI’s block diagram.

For the first few labs we’ll use the myDAQ.