Complete the following steps to create a VI that takes a number
representing degrees Celsius and converts it to a number
representing degrees Fahrenheit.
- Display the block diagram by clicking it or by
selecting
Window>> Show Block Diagram.
LabVIEW creates corresponding control and indicator
terminal icons on the block diagram when you place
controls and indicators on the front panel. The
terminals represent the data type of the control or
indicator. You should see two double-precision,
floating-point terminals on the block diagram, one
indicator, and one control.
Control terminals have a thicker border than indicator
terminals.
-
Place the
Multiply function, located on the
Functions>>Arithmetic & Comparison>>Express
Numeric palette, on the block diagram to the right of
the deg C indicator. If the
Functions palette is not visible, right-click
an open space on the block diagram workspace to display it.
-
Place the
Add function, located on the
Functions>>Arithmetic & Comparison>>Express Numeric
palette, on the block diagram to the right of the
Multiply function.
-
Place a Numeric Constant, located on the
Functions>>Arithmetic & Comparison>>Express Numeric
palette, to the lower left of the
Multiply function. Type 1.80 in
the constant. When you first place a numeric constant, it is
highlighted so you can type a value. If the constant is no
longer highlighted, double-click the constant to activate
the Labeling tool.
-
Place a
Numeric Constant, located on the
Functions>>Arithmetic & Comparison>>Express
Numeric palette, to the left of the Add
function. Type 32.0 in the constant.
-
Use
the Wiring tool, shown in Media 9, to wire the icons as shown in Figure 2.
-
To wire from one terminal to another, use the
Wiring tool to click the first terminal,
move the tool to the second terminal, and click the
second terminal. You can start wiring at either
terminal.
-
You can bend a wire by clicking to tack down the wire
and moving the cursor in a perpendicular
direction. Press the
spacebar to toggle the
wire direction.
-
To identify terminals on the nodes, right-click the
Multiply and Add functions
and select Visible Items>>Terminals from
the shortcut menu to display the connector pane on the
block diagram. Return to the icons after wiring by
right-clicking the functions and selecting
Visible Items>>Terminals from the shortcut menu
to remove the checkmark.
-
When you move the
Wiring tool over a
terminal, the terminal area blinks, indicating that
clicking will connect the wire to that terminal and a
tip strip appears, displaying the name of the
terminal. If the Context Help window is
open, the terminal area also blinks in the
Context Help window.
-
To cancel a wire you started, press the
<Esc> key, right-click, or click the
terminal where you started the wire.
-
Display the front panel by clicking it or by selecting
Window>>Show Front Panel.
-
Save the VI as
Convert C to F.vi in the
C:\Exercises\LabVIEW Basics I directory.
-
Enter a number in the numeric control and run the VI.
-
Use the Operating tool, shown in Media 11, or the Labeling tool to
double-click the numeric control and type a new number.
-
Click the
Run button, shown at left, to run the VI.
-
Try several different numbers and run the VI again.
-
Right-click the icon in the upper right corner of the front panel
window and select
Edit Icon from the shortcut menu.
The Icon Editor dialog box appears.
-
Double-click the Select tool, shown in Media 13, on the left side of the Icon Editor
dialog box to select the default icon.
-
Press the
<Delete> key to remove the default
icon.
-
Double-click the Rectangle tool, shown in Media 14, to redraw the border.
-
Create the icon in Figure 3.
-
Double-click the Text tool, shown in Media 16, and change the font to Small
Fonts .
-
Use the
Text tool to click the editing area
where you will begin typing.
- Type
C and F. While the
text is active, you can move the text by pressing the
arrow keys.
-
Use the Pencil tool,
shown in Media 17, to create the arrow.
To draw horizontal or vertical straight lines, press
the <Shift> key while you use the
Pencil tool to drag the cursor.
-
Use the
Select tool and the arrow keys to
move the text and arrow you created.
-
Select the
B & W icon and click the
256 Colors button in the Copy from
section to create a black and white icon, which
LabVIEW uses for printing unless you have a color
printer.
-
Select the
16 Colors icon and click the
256 Colors button in the Copy from
section.
-
When you complete the icon, click the
OK
button to close the Icon Editor dialog
box. The icon appears in the upper right corner of the
front panel and block diagram.
-
Right-click the icon on the front panel and select
Show Connector from the shortcut menu to define the
connector pane terminal pattern. LabVIEW selects a default
connector pane pattern based on the number of controls and
indicators on the front panel. For example, this front panel
has two terminals, deg C and deg F
, so LabVIEW selects a connector pane pattern with
two terminals, shown in Media 18.
-
Assign the terminals to the numeric control and numeric
indicator.
-
Select
Help>>Show Context Help to display
the Context Help window.
-
Click the left terminal in the connector pane. The
tool automatically changes to the
Wiring tool, and the terminal turns
black.
-
Click the
deg C control. A marquee
highlights the control on the front panel.
-
Click an open space on the front panel. The marquee
disappears, and the terminal changes to the data type
color of the control to indicate that you connected the
terminal.
-
Click the right terminal in the connector pane, and
click the
deg F indicator.
-
Click an open space on the front panel. Both terminals
of the connector pane are orange.
-
Move the cursor over the connector pane. The
Context Help window shows that both terminals
are connected to double-precision, floating-point
values.
-
Save and close the VI. You will use this VI later in the course.
"A full introductory course on programming with LabVIEW."