First Values Keep Replacing Old one despite file position set

[concacid]

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

[RavensFan]

It's impossible to debug a paragraph.

Try attaching your VI.

[concacid]

I attach the VI.

Thanks

[Taki1999 · Accepted solution]

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.

[concacid]

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

[GerdW]

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…

[concacid]

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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

[concacid]

The state machine and 'all wires' did the trick.

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

Thanks guys