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First Values Keep Replacing Old one despite file position set

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I have saved to file and I have used the save to file function.

It works well and for each run I have 6 values, however on the second run there, the first new value replaces the old first value but others work well.

What can I do?. I set the position to end for each value collected.

 

Thanks

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It's impossible to debug a paragraph.

 

Try attaching your VI.

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I attach the VI.

 

Thanks

 

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Solution
Accepted by topic author concacid

I think you would benefit greatly from looking at the LabVIEW tutorials.

 

A few things right off the bat:

Try and get away from using Stacked Sequences to repeat code. You'll do much better with a state machine or by using a subVI.

Don't use a local variable for the FileRefnum. Use the wire itself.

Message 4 of 8
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Thanks. 

 

I know how to use a state machine but then this is a relatively simple program and runs peferctly but for the svaing option.

 

I would trying using the wire for the file refnum

 

Thanks

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Hi concacid,

 

even for this "relatively simple" program you should THINK DATAFLOW and use wires in favor of local variables…

In your case an autoindexing loop for your 6 channels would be ok too!

 

That being said:

- Using file refnums should append writes at the end of the file. Please test this after replacing all "refnum out" variables by wires.

- When you insist on using SetFilePosition you should set the write position before doing the actual write, not afterwards. Seems more logical to me…

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 6 of 8
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@GerdW wrote:

Hi concacid,

 

even for this "relatively simple" program you should THINK DATAFLOW and use wires in favor of local variables…

In your case an autoindexing loop for your 6 channels would be ok too!

 

That being said:

- Using file refnums should append writes at the end of the file. Please test this after replacing all "refnum out" variables by wires.

- When you insist on using SetFilePosition you should set the write position before doing the actual write, not afterwards. Seems more logical to me…


Thank you!

Points noted

 

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Message 7 of 8
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The state machine and 'all wires' did the trick.

 

Scrap the local variable then. Its more or less useless.

 

Thanks guys

 

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