When you open a file you make a copy of the data on disc and put it in memory somewhere the application that opened it knows about.
In your case a spreadsheet open in Excel will have its file locked for its exclusive use. This prevents the file from getting updates by more than one application which would most assuradly cause unintended consequences (the file would get corupted.)
In other words You only think you want to write data from LabVIEW to a file open for editing in Excel - You really don't want to do this
"Should be" isn't "Is" -Jay
