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How to read data from a file that is already open by another program


I have made IV, where I'm trying to read data from a log file, that is being updated by another program while my IV runs.
To be clear, this program writes data continuously to this file and I want to read from the file in LV at the same time.


The problem is that LV reports an error when I'm trying to read the log file, even if I use to "read only" mode.
I believe that the program that is producing the file, have some kind of lock on the file. I have tryed to copy the file and then reading from the copied file, but LV throws already an error when I try to copy the file.


Has anyone tryed this, and found a solution.?


Additional info: The program that produces the file is STM Studio 


Best Regards

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Message 1 of 5

Hi Alha,


when that file is locked by the other program you can't do anything about that - apart from quitting that other program. Probably this isn't an option to you…

Best regards,

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
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Message 2 of 5

This is probably worth a try. We all have to jump through hoops provided by Microsoft from time to time!

I know I have not exactly given you a working solution but it may get you going

All the best
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Message 3 of 5

Hey Michael


Thanks for the proposal..


It worked, but the program (hobocopy) takes to long, to copy the file,

about 10 sec. and I want to do it much faster, less then 10ms.



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Message 4 of 5
A friend of mine suggested tail, a linux thing. I found a possible solution here:

Let me know how you get on here. 10ms is a tough one. I dont think a faster drive like an ssd will help get close, there is the possibility of a simulated ram drive but I guess could be problematic. Tail sounds ideal so best of luck.
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