Format Into File

Use the Format Into File function to format string, numeric, path, and Boolean data as text and write the text to a file. Often you can use this function instead of separately formatting the string with the Format Into String function or Build Text Express VI and writing the resulting string with the Write Characters To File VI or Write File function.

Use the Format Into File function to determine the order in which the data appears in the text file. However, you cannot use this function to append data to a file or overwrite existing data in a file. For these operations, use the Format Into String function with the Write File function. You can wire a refnum or path to the input file terminal of the Format Into File function, or you can leave this input unwired for a dialog box to prompt you for the filename.

In the block diagram shown in Figure 1, the Open/Create/Replace File VI opens a file, and the For Loop executes five times. The Format Into File function converts the iteration count and the random number to strings and places the tab and end of line characters in the correct positions to create two columns and one row in spreadsheet format. After the loop completes five iterations, the file closes, and the VI checks the error condition.

Figure 1

This VI creates this text file, where an arrow (→) indicates a tab, and a paragraph symbol (¶) indicates an end of line character.

	  0→ 0.798141¶
	  1→ 0.659364¶
	  2→ 0.581409¶
	  3→ 0.526433¶
	  4→ 0.171062¶
	

You can open the previous text file in a spreadsheet application to display the spreadsheet shown in Figure 2.

Figure 2

Write LabVIEW Measurement File

In the block diagram shown in Figure 3, the Write LabVIEW Measurement File Express VI includes the open, write, close, and error handling functions. It also handles formatting the string with either a tab or comma delimiter. The Merge Signals function combines the iteration count and the random number into the dynamic data type.

Figure 3

The dialog box in Figure 4 shows the configuration for the Write LabVIEW Measurement File Express VI.

Figure 4

This VI creates a .lvm file which you can open in a spreadsheet application. Figure 5 shows an example of the spreadsheet created by the previous configuration of the Write LabVIEW Measurement File Express VI.

Figure 5

Refer to the lesson on Data Acquisition and Waveforms, for more information about the Write LabVIEW Measurement File and Read LabVIEW Measurement File Express VIs.