Front Panel Open a blank VI and build the front panel shown in .

Place the Meter, located on the Controls>>Numeric Indicators palette, on the front panel. Configure the meter scale for 0.0 to 0.4. Use the Labeling tool to double-click 10.0 and type 0.4. You might need to enlarge the meter to display the scale as shown in the example. Place a Vertical Toggle Switch, located on the Controls>>Buttons & Switches palette, on the front panel. Configure the toggle switch to a default value of False and a mechanical action of

Latch When
		  Pressed

. Create two free labels, Off and On, using the Labeling tool.

Block Diagram Build the block diagram shown in .

Place the DAQ Assistant Express VI located on the

Functions>>Input
		  palette

, on the block diagram. Configure this VI to read an analog input channel and return the voltage. Select Analog Input>>Voltage for the measurement to make. Select Dev1>>ai0 for the physical channel. Click the Finish button. The Analog Input Voltage Task dialog box appears. Configure the

Task
		      Timing

to Acquire 1 Sample. Click the OK button to close the

Analog Input Voltage Task
		      Configuration

dialog box. This saves the settings specified for the task in the

DAQ
		      Assistant Express

VI. Place the

Wait Until Next ms
		  Multiple

function, located on the

Functions>>All Functions>>Time &
		  Dialog

palette, on the block diagram. Right-click the input and select Create Constant from the shortcut menu. Type 100 in the constant to cause the loop to execute every 100 ms. Place the

Unbundle by
		  Name

function, located on the Functions>>All Functions>>Cluster palette, on the block diagram. Use this function to access the status from the error cluster. Place the Or function, located on the

Functions>>Arithmetic
		  & Comparison>>Express Boolean

palette, on the block diagram. This function stops the loop if an error occurs or the user clicks the power switch on the front panel. Save the VI as Voltmeter.vi in the C:\Exercises\LabVIEW Basics I directory. You will use this VI later in the course. Display the front panel and run the VI. The meter displays the voltage the temperature sensor outputs. Place your finger on the temperature sensor and notice that the voltage increases.

Scales The temperature sensor on the DAQ Signal Accessory outputs the voltage in degrees Celsius, scaled by 100. In order to convert the voltage into degrees Celsius, it is necessary to multiply the voltage by 100. You could multiply the output of the DAQ Assistant Express VI by 100, or configure the DAQ Assistant Express VI to automatically scale the voltage. Using the capabilities that exist within the VI reduces block diagram clutter. Double-click the DAQ Assistant to display the Analog Input Voltage Task Configuration dialog box. Select Create New in the

Custom
	      Scaling

pull-down menu. Select Linear and name the scale temperature. Click the Finish button. A dialog box appears where you can scale the data by a multiplier and an offset. Set the slope to 100 and the

Scaled
		  Units

to Celsius. Click the OK button to close the dialog box. In the

Analog Input Voltage Task
	      Configuration

dialog box, set the

minimum input
	      range

to 0, set the maximum input range to 100, and click the OK button to return to the block diagram. Run the VI. The temperature displays in the meter. The temperature values are 100 times greater than the voltage values. Change the meter scale to see the correct values. Stop the VI. Save the VI but do not close it. You will use the VI in the Measurement Averaging VI exercise.