Folder Monitoring for File Changes

[Waterppk]

I searched around the forums/online and I can't seem to find anyone who's used LabVIEW to monitor folders for changes in files/folders. I'm collecting data on a network drive in my building and then hoping to have my data post processor monitor that folder for generated data, when data is generated I then want the post processor to automatically process the data but not touch any old data.

Any thoughts?

[Ton Plomp]

I know that someone posted an xcontrol with this functionality.

ton

[Christian_L]

I searched around the forums/online and I can't seem to find anyone who's used LabVIEW to monitor folders for changes in files/folders. I'm collecting data on a network drive in my building and then hoping to have my data post processor monitor that folder for generated data, when data is generated I then want the post processor to automatically process the data but not touch any old data.

Sounds like a very good application for LabVIEW.

Here's a simple example of implementing this.

[ShaunR]

Sounds like a very good application for LabVIEW.

Here's a simple example of implementing this.

Be even better if we could catch windows messages in the event structure!

Edited October 2, 2009 by ShaunR

[Ton Plomp]

Be even better if we could catch windows messages in the event structure!

I should have make it more clear but the XControl I linked to uses the windows messages for this.

I know that someone posted an xcontrol with this functionality.

ton

[ShaunR]

I should have make it more clear but the XControl I linked to uses the windows messages for this.

Well. Yes and no. It uses .NET so its a bit like saying a vi creates Word documents when, in fact, it is an automation interface to Microsoft Word and Word creates the document. No word, no document. No .NET, no messages.

[shinton]

Be even better if we could catch windows messages in the event structure!

 

I know that someone posted an xcontrol with this functionality.

ton

 

The disadvantage of using the .NET solution is that it can't be implemented on a real-time target.  If I want my RT controller to FTP a log file to me whenever a new one is created then I'll have to use something like Christian_L's example above (which looks pretty good to me).

[Omar Mussa]

I didn't look at Ton's attachment but I have done this in the past using a .NET System Filewatcher Object and registering a callback VI for when the .NET event fires.  It works pretty well, the only challenge was that the callback was called in a LabVIEW context that you can't debug directly.

[shinton]

I know that someone posted an xcontrol with this functionality.

ton

 

Also here is another post with a similar (.NET) solution.  I haven't looked at both to compare them.

[Omar Mussa]

Sounds like a very good application for LabVIEW.

Here's a simple example of implementing this.

foldermonitor.PNG

 

BTW - the problem with doing the array checking for this operation is that it can become a pretty big performance hit to poll the folder and list all files and search for all changes, especially if the number of files grows large.  Plus, you may need other features (like file removed or file updated) and you end up with more and more trouble when you try to recreate that functionality.  I think the .NET solution is the best long run solution for this problem (as long as you're on a Windows platform).

[GregFreeman]

BTW - the problem with doing the array checking for this operation is that it can become a pretty big performance hit to poll the folder and list all files and search for all changes

If you are on a non windows OS, you could use the "get file/directory info" VI and just monitor the last mod timestamp. Then only call the directory listing once at startup to get the initial list, and any time the last mod timestamp changes. This reduces the number of times it needs to do the list/compare.

Edited May 1, 2014 by GregFreeman