Edit "Write LabVIEW measurement file" header

[Bernd R.]

Hello everyone, how do I change the header of the Write LabVIEW measurement file VI? For example I want "PN, Lot#, Station ID" instead of "Writer_Version, Reader_Version, Separator" and only "Std Dev" instead of "Collected (Std Dev)". Thank you!

[Joe_H]

hey bernd it's me again. What you will need to do if you want to use this Vi is place it on the block diagram. right click on it then select open front panel and then convert. Go to the block diagram and dig down in the vi until you find a Vi called ex_Headertospreadsheetstr open that up and save it as a different name then change the constants to what you want.

Joe

[Bernd R.]

Hey Joe, thanks for your answer. Unfortunately I'm not able to find that VI anywhere. If you could help me find it, that would be great. I wire it then to the converted "Write LVM" VI, right?

Bernd

[Joe_H]

Hey Bernd here are the steps to finding the VI Ex_headertosprdstr.VI

1.Place write LVM express VI on block diagram.

2.Right click on VI and select open front panel, then select convert and this will open up the write LVM front panel.

3.Go to the block diagram of the Write LVM and there will be another express VI in there called EX_subfilewrite. Open its front panel and go to the block diagram.

4.Then inside the inner case structure (false) ther is another vi called write data all. Open that up and go to the block diagram.

5.Then inside the inner case structure (true) ther is a smaller case structure (true) and inside that you will find the Ex_headertosprdstr VI open the block diagram and modify as needed and save under different nam
e so as not to corrupt the original vi.

Hope this helps you out.

Joe

[Bernd R.]

Thanks Joe, I would have never found it without your help. I still have a problem: I open the VI and as long as I leave it untouched it works. I can stop and restart my application and it will append new data to the report. I can delete the report, it will generate a new one...But when I do the slightest change (see attachment) it gives me "Error 100: LabVIEW: File contains erroneous data. Normally for user data files." when I restart the application. When I delete the report it will create a new one, but then again when I stop and restart the error shows up. It seems to not be able to append new data to the file. But it also doesn't create a new one.

[SarahM]

Hey Bernd,

The reason you're getting Error 100 is that by modifying the header the file no longer fits the LVM file format. Here's a link to a document that discusses this format in more detail:

Specification for the LabVIEW Measurement File (.lvm), Version 1.0

I would suggest not using the Write/Read LVM express VIs. Depending on your data I would suggest using some of the file writing VIs directly. This way you can control directly what data you're writing to file. You can find lots of examples by going to Help >> Find Examples and searching for file. I would suggest looking at the Write to Text File exampl
e. You can customize this example to first write a header.

I hope this helps!

Sarah Miracle
National Instruments