| << Chapter < Page | Chapter >> Page > |
Complete the following steps to create a VI that reads a measurement from the temperature sensor on the DAQ SignalAccessory and displays the temperature in Celsius or Fahrenheit.
The sensor returns a voltage proportional to temperature. For example, if the temperature is 23, the sensor output voltage is 0.23 V. The sensor is connected to Channel 0 ofDevice 1. Device 1 is the DAQ device. On some systems, the DAQ device may have another device number.
LabVIEW dialog box, click the arrow on
the
New button and select
Blank VI from the shortcut menu or press the
<Ctrl-N> keys to open a blank VI.Controls>>Numeric Indicators palette, on the
front panel.Temperature in the label and press
the
<Enter> key or click the
Enter button on the toolbar, shown at left.Visible
Items>> Digital Display from the shortcut menu to
show the digital display for the thermometer.Controls>>Buttons&Switches palette, on the front panel.Temp Scale in the label and press the
<Enter> key or click the
Enter button.Labeling tool, shown in
, to place a free label,
deg
C , next to the
True position of the
switch. If you are using automatic tool selection,double-click the blank area of the front panel to begin
typing a free label.deg F , next to the
False position of the switch.Context
Help window when you move the cursor over the VI icon.
File>>VI Properties to
display the
VI Properties dialog box.Documentation from the
Category pull-down menu.VI description text box:
This VI measures temperature using the temperaturesensor on the DAQ Signal Accessory. OK button.Context Help window when
you move the cursor over the objects and tip strips appear onthe front panel
or block diagram when you move the cursor over the objects whilethe VI runs.
Description and Tip from the shortcut menu.Description text box:
Displays the temperature measurement. temperature in the
Tip text box.OK button.Description and Tip from the shortcut menu.Description text
box:
Determines the scale (Fahrenheit or Celsius) to
use for the temperature measurement. scale - C or F in the
Tip text box.OK button.Help>>Show Context Help to display the
Context Help window.Context Help window.Window>>Show Block Diagram to display the
block diagram .
DAQ Assistant Express VI, located on the
Functions>>Input palette, on the block diagram.
When you place this Express VI on the block diagram the DAQAssistant configuration dialog box appears.
Analog Input>>Voltage for the type of
measurement to make.Dev1>>ai0 (or
Dev2>>ai0 ) for the physical channel and
click the
Finish button.Settings tab, select
Custom Scaling>>Create
New . Select a
Linear scale. Name
the scale
Temperature . Enter a
slope
scale of
100 . Click the
OK button.min = 0 . Set
max = 100 Acquire 1 Sample option on the
Task Timing tab.
Click the
OK button.
(Demo) Read Voltage VI, located in the
C:\Exercises LabVIEW Basics I directory.Convert from Dynamic Data Express VI, located
on the
Functions>>Signal Manipulation palette,
on the block diagram. This VI converts the dynamic datatype. In the configuration dialog box, select
Single
scalar in the
Resulting data type listbox.Convert C to F VI on the block diagram. Select
Functions>>All Functions>>Select a VI , navigate
to
C:\Exercises\LabVIEW Basics I\Convert C to
F.vi . This VI converts the Celsius readings to
Fahrenheit.Select function, located on the
Functions>>Arithmetic&Comparison>>Express
Comparison palette, on the block diagram. This
function returns either the Fahrenheit (
False )
or Celsius (
True ) temperature value, depending
on the value of
Temp Scale . Use the
Positioning tool to place the icons as shown in
the
block diagram and use the
Wiring tool to wire them together.
Visible Items>>Terminals from the
shortcut menu.Window>>Show Front Panel .Run Continuously button, shown at left, to run
the VI continuously.Run Continuously button again to
stop the VI. This allows the VI to finish the current run ofthe VI.Thermometer VI as a subVI. The following icon is an example. If
necessary, create a simpler icon to save time.
Edit Icon from the shortcut menu. The
Icon Editor dialog box appears.Select tool, shown at left, on the left
side of the
Icon Editor dialog box to
select the default icon.<Delete> key to remove the
default icon.Rectangle tool, shown at
, to redraw the border.Pencil tool, shown in
, to draw an icon that represents the
thermometer.Foreground and Fill tools to color
the thermometer red.
<Shift> key while you use the
Pencil tool to drag the cursor.Text tool, shown in
, and change the font to
Small
Fonts .Temp . Reposition the text if
necessary.B&W icon and select
256 Colors in the
Copy from section to create a black and white icon, which LabVIEW
uses for printing unless you have a color printer.OK button. The icon appears in the upper right corner of
the front panel.Show Connector from the shortcut menu and assign terminals to the switch
and the thermometer.
Temp Scale control. The left
terminal turns green.Temperature indicator. The right
terminal turns orange.Thermometer.vi in the
C:\Exercises\ LabVIEW Basics I directory.You
will use this VI later in the course.
Notification Switch
Would you like to follow the 'Labview graphical programming' conversation and receive update notifications?
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|