Why do I get a NI-488 error massage when writing into a file and at the same time copiyng this file with a backup softwarre like Easy2Sync?

[Serdj]

I have a small LabVIEW program which writes random numbers very fast into a ASCII-file. I want that file to be copied to a new position every 10 min. Therefor I use a backup/synchronisation software which is doing a copy operation every 10 min. It works fine a certian amount of time and after a while I get either an LabVIEW error (LabVIEW: Fiel already open: NI-488 Comand requieres GPIB Controller to be System controller) or an backup-software error (couldn´t open file...whatever). I´m guessing, it has something to do with file-access but I don´t know why?!? If I run the LabVIEW program and I copy and paste the random-number-file with the windows explorer very fast (pressing ctrl+v rapidly) while LabVIEW is still writing into this file, no error appears. Can sombody help me?

[GerdW]

Hi Serdj,

you don't get a GPIB error, the error number has just 2 different explanations...

Well, you have two programs accessing the same file. One program just wants to make a copy, the other (LabView) is trying to write to the file. When copying a file that is written to you get inconsistent results! That's why one of both programs is complaining an error...

You can't have write and read access at the same time! (But you can have more than one read access at the same time...)

[Serdj]

Thanks for the reply. And I also wrote another program with another software called TestPoint which is only reading from this one file, while LabVIEW is writing, and I have no problem with that.

Edit to my first thread: I was rapidly pressing ctrl+v in the windows explorer trying to copy that file as fast as possible while LabVIEW was writing into it, and after a while a got an windows error saying that this file is being used by another program and canot be copied.

Message Edited by Serdj on 10-06-2008 07:31 AM

[GerdW]

Hi Serdj,

I don't think "rapidly pressing ctrl-v" will speed up winexplorer (or windows)...

Still true: you can't have read and write access at the same time (under usual circumstances like random access and standard file systems)!