Unexplained error 550 with FTP Get File

[knicewar]

My app FTPs a set of files (none very big) from my RT PXI target but sometimes I get a 550 FTP error.  I get this failure randomly about 20% of the time.  So I figured I could increase my chances by putting the FTP Get File in a loop and retry on errors.  This didn't work -- it just kept failing.  So then I added a delay thinking the FTP server needed some time to reset.  I set it to 5 seconds between retries and that didn't help either.  Now before you ask, yes, the files are there.  While my VI was trying and failing, I used an explorer window to look at the FTP dir and all the files I was looking for were there AND I could copy them using that client.  The file names never change between runs anyway, so why would it work some times and not others?  It seems like the FTP Get Files VI is getting stuck.  The only way to unstuck it is to restart my main VI.

[MikeS81]

Hi knicewar,

did you close all reference after using them? Maybe an open connection is the problem.

Mike

[AlphaTreo]

Try to change from an active transfer to a passive one via one of the Boolean inputs on the bottom of the FTP Get File VI.  This has something to do with firewalls.  It would suprise me of it works since you are having sporatic issues.  I woulf think that it would work all the time or not at all.  It is something easy to try, though.

[knicewar]

I'm using passive FTP.  Active made it take forever, which is odd because I have a dedicated non-routable network to the PXI and no firewalls.

[knicewar]

Here's some more info.  I discovered that the problem seemed to have something to do with trying to get a file before the target had closed it.  This will give a 550 error on other FTP clients as well.  However, shortly after the host starts trying to get the file, the target does close it and so the FTP get SHOULD eventually succeed.  What I think was happening was that my retry loop was using a shift register for the error so the next iteration was not even trying.  But I think the best fix is for the host to wait for a signal from the target that it's done with the files before trying to get them.

[AlphaTreo]

That seems like a valid strategy.  I hope it works!

[Jon_S.]

I know I get that error if I try to manually delete an RT exe from the startup folder via FTP.  The work around for this is to first rename the file then delete it (e.g. renaming startup.rtexe to startup1.rtexe then deleting.)  Are you trying to move or just copy files? Is one of the files a startup exe?

http://digital.ni.com/public.nsf/allkb/6EDCBF0F0498814F86256B570080DD20

Also, let me know if the picture on this site doesn't show up on your computer.

Message Edited by Jon S. on 04-11-2009 02:56 PM