Simple Data Logger Block Diagram Open the Measurement Averaging VI located in the C:\Exercises\LabVIEW Basics I directory. Modify the block diagram to log the acquired data as shown in .

Place the

Write LabVIEW
	      Measurement File

Express VI, located on the Functions>>Output palette, on the block diagram. This Express VI stores the data acquired from the DAQ device. In the

Configure Write LabVIEW
	      Measurement File

dialog box that appears, set the following options: Set the Action to

Ask user to
		  choose file

for the filename. Set the Segment Headers to

One
		  header only

to provide a header for all of the data. The header contains information about the sampling rate and the time when the sample was taken. Set X Value Columns to

One column
		  per channel

to provide a table of data that can be read by any spreadsheet editor or an ASCII text file editor. Set the Delimiter to Tab to make it easy for a spreadsheet editor to determine where a column of data starts in the file. Click the OK button to close the dialog box. Place the Merge Errors VI, located on the

Functions>>All Functions>>Time
	      & Dialog

palette, on the block diagram. It is important to catch errors with both DAQ and file I/O, and because the code has a parallel structure it is necessary to merge the errors from all of the parallel operations to determine if the code is functioning properly. Select File>>Save As to save the VI as Simple Data Logger.vi in the C:\Exercises\LabVIEW Basics I directory. Run the VI. A filename prompt appears. Name the file logger.lvm in the C:\Exercises\LabVIEW Basics I directory. Stop and close the VI.

Simple Data Reader Front Panel Open a blank VI and build the front panel shown in by placing a waveform chart, located on the Controls>>Graph Indicators palette, on the front panel.

Block Diagram Build the block diagram shown in .

Place the

Read LabVIEW
		  Measurement File

Express VI, located on the Functions>>Input palette, on the block diagram. Because this Express VI reads data located in a LabVIEW measurement file one data point at a time, it must be placed in a loop. In the Configure Read LabVIEW Measurement File dialog box that appears, set the following options: In the Action section, place a checkmark in the

Ask user to choose
		      file

checkbox. Set the Segment Size to Retrieve segments of original size so that all the data stored in the file is retrieved. Set Time Stamps to

Relative
		      to start of measurement

. Because the dynamic data type stores information about the signal timing, this setting aligns the data with the time of the measurement. In the Generic Text File section, remove the checkmark from the

Read generic
		      text files

checkbox because the data is stored in a LabVIEW measurement file. Click the OK button to close the dialog box. Place the Unbundle by Name function, located on the

Functions>>All
		  Functions>>Cluster

palette, on the block diagram. Place the Or function, located on the

Functions>>Arithmetic
		  & Comparison>>Express Boolean

palette, on the block diagram. Wire the EOF? output of the

Read
		  LabVIEW Measurement File

function to the Or function. Wire the status output of the error cluster to the second input of the Or function. This stops the While Loop when the entire LabVIEW Measurement File has been read or when an error occurs. Save the VI as Simple Data Reader.vi in the C:\Exercises\LabVIEW Basics I directory. Display the front panel, and run the VI. In the filename prompt that appears, select the logger.lvm file that you created earlier. The data that was stored in the LabVIEW Measurement File appears in the waveform chart. You might need to rescale or autoscale the y-axis of the waveform chart to display the data. Close the Simple Data Reader VI.