I want to add header to a file. Header must contain date/time and scan rate (it's a DAQ vi)

[Giulia]

I managed to solve the problem using solution in attachment, but it looks quite primitive...

Additional problem:
Suppose the case:
Acquisition 1 --> header and results are written in "results.lvm"
Acquisition 2 --> I want new data to be written in the same destination file "results.lvm" (append to the file). But I need the header to know when Acquisition 2 begins. Unfortunately, what happens is that new data are appended immediately after old data; header is updated at the top of the page and information on Acquisition 2 replaces that one on Acquisition 1.

Here is the reason because I need a more efficient header maker.

[Jeremy Braden]

I looked at the VI, and you should not think that it is bad. It works and there is nothing simplier you can do to format the header.
working simple solution=good solution

I think that you may want to reapproach writing the data to file. The customization you want in the saved file will require extensive recoding of several VIs. Have you considered just writing your own algorithm for recording data? It is not difficult to learn the basic techniques then you can modify it all you want. Look on the string palette and the shipping examples for writing text to file.