Data from for loops

[Will]

Hello.
I am relatively new to LabVIEW and would appreciate someone's help.
I am running three cascaded while loops.
I need to be able to pull out data from the loops as the iterations are being
performed from inside the inner loop, then four more loops in real time and
display them on a string indicator. In other words, as the iterations are
being performed, the string indicator will display the values inside the
loop.
I hope I explained this well enough. Thanks in advance for your help.

Will

[Will]

I apologize... the subject should say from while loops. On a sidenote to
this. I have managed to do this with for loops. However, I cannot abort
my operation with for loops, and this is an option I do need. Darn for loops!!
Thanks again. Will

"Will" wrote:
>>Hello.>I am relatively new to LabVIEW and would appreciate someone's help.>I
am running three cascaded while loops.>I need to be able to pull out data
from the loops as the iterations are being>performed from inside the inner
loop, then four more loops in real time and>display them on a string indicator.
In other words, as the iterations are>being performed, the string indicator
will display the values inside the>loop.>I hope I explained this well enough.
Thanks in advance for your he
lp.>>Will

[CraigGraham]

Can't make out exactly what you're on about but there shouldn't be a
difference between the FOR loop and the WHILE loop approach. In both cases
to get an indicator to update as the loop iterates you simply put the
terminal of that indicator inside the loop.

The only difference I'm aware of between the way data comes out of the two
loops is that wires coming out of a FOR loop default to auto-indexing, and
wires coming out of a WHILE don't. Do when a wire comes out of the for loop
it becomes an array, whilst the wire coming out of the while loop remains as
the last data value the wire held. If this is your problem, just pop up with
the right mouse button over the "blob" where the wire leaves the loop and
you'll see the "Enable auto-indexing" option.

Will
nterroza.w@bodycote.ca> wrote in message
news:3a81cce4@newsgroups.ni.com...
>
> I apologize... the subject should say from while loops. On a sidenote to
> this. I have managed to do this with for loops. However, I cannot abort
> my operation with for loops, and this is an option I do need. Darn for
loops!!
> Thanks again. Will

[Greg Caesar]

Mr Graham is correct, the first thing you should try is to simply place the
indicator inside the WHILE or FOR loop. However, in some cases this is not
practical - perhaps the most common being when your loop is in a sub-vi. In
this case you could write to a global variable inside the loop. In your
main VI, you can then have a 2nd loop, parallel to the first, reading from
the global and updating an indicator on your front panel.

There are several global variables examples that ship with LabVIEW - take a
look at them and see if they are helpful. If not, I have a sample program
that does the above on my machine at work. Just let me know if you are
interested and I can send it tomorrow if needed.

Regards,
Greg

Craig Graham wrote in message
news:3a826d9a@newsgroups.ni.com...
> Can't make out exactly what you're on about but there shouldn't be a
> difference between the FOR loop and the WHILE loop approach. In both cases
> to get an indicator to update as the loop iterates you simply put the
> terminal of that indicator inside the loop.
>
> The only difference I'm aware of between the way data comes out of the two
> loops is that wires coming out of a FOR loop default to auto-indexing, and
> wires coming out of a WHILE don't. Do when a wire comes out of the for
loop
> it becomes an array, whilst the wire coming out of the while loop remains
as
> the last data value the wire held. If this is your problem, just pop up
with
> the right mouse button over the "blob" where the wire leaves the loop and
> you'll see the "Enable auto-indexing" option.
>
> Will wrote in message
> news:3a81cce4@newsgroups.ni.com...
> >
> > I apologize... the subject should say from while loops. On a sidenote
to
> > this. I have managed to do this with for loops. However, I cannot
abort
> > my operation with for loops, and this is an option I do need. Darn for
> loops!!
> > Thanks again. Will
>
>
>

Craig Graham wrote in message
news:3a826d9a@newsgroups.ni.com...
> Can't make out exactly what you're on about but there shouldn't be a
> difference between the FOR loop and the WHILE loop approach. In both cases
> to get an indicator to update as the loop iterates you simply put the
> terminal of that indicator inside the loop.
>
> The only difference I'm aware of between the way data comes out of the two
> loops is that wires coming out of a FOR loop default to auto-indexing, and
> wires coming out of a WHILE don't. Do when a wire comes out of the for
loop
> it becomes an array, whilst the wire coming out of the while loop remains
as
> the last data value the wire held. If this is your problem, just pop up
with
> the right mouse button over the "blob" where the wire leaves the loop and
> you'll see the "Enable auto-indexing" option.
>
> Will wrote in message
> news:3a81cce4@newsgroups.ni.com...
> >
> > I apologize... the subject should say from while loops. On a sidenote
to
> > this. I have managed to do this with for loops. However, I cannot
abort
> > my operation with for loops, and this is an option I do need. Darn for
> loops!!
> > Thanks again. Will
>
>
>

[George Callara]

Another more efficient way of doing this, when the loop is not in a sub-vi,
is to write the data into a queue inside the for/while loop and then somewhere
else in your vi read data from the queue. In this way data can be passed
in and out of loops with out the drawbacks of using global/local variables.

If in a subvi: Create an indicator in your main vi, pass a control reference
of that indicator into the subvi and alter the value of the indicator using
a property node. Anytime you can avoid using globals or locals, you should
as this can slow your program and introduce race conditions.
"G Caesar" wrote:
>Mr Graham is correct, the first thing you should try is to simply place
the>indicator inside the WHILE or FOR loop. However, in some cases this
is not>practical - perhaps the most common being when your loop is in a sub-vi.
In>this case you could write to a global variable inside the loop. In your>main
VI, you can then have a 2nd loop, parallel to the first, reading from>the
global and updating an indicator on your front panel.>>There are several
global variables examples that ship with LabVIEW - take a>look at them and
see if they are helpful. If not, I have a sample program>that does the above
on my machine at work. Just let me know if you are>interested and I can
send it tomorrow if needed.>>Regards,>Greg>>Craig Graham
wrote in message>news:3a826d9a@newsgroups.ni.com...>> Can't make out exactly
what you're on about but there shouldn't be a>> difference between the FOR
loop and the WHILE loop approach. In both cases>> to get an indicator to
update as the loop iterates you simply put the>> terminal of that indicator
inside the loop.>>>> The only difference I'm aware of between the way data
comes out of the two>> loops is that wires coming out of a FOR loop default
to auto-indexing, and>> wires coming out of a WHILE don't. Do when a wire
comes out of the for>loop>> it becomes an array, whilst the wire coming out
of the while loop remains>as>> the last data value the wire held. If this
is your problem, just pop up>with>> the right mouse button over the "blob"
where the wire leaves the loop and>> you'll see the "Enable auto-indexing"
option.>>>> Will wrote in message>> news:3a81cce4@newsgroups.ni.com...>>
>>> > I apologize... the subject should say from while loops. On a sidenote>to>>
> this. I have managed to do this with for loops. However, I cannot>abort>>
> my operation with for loops, and this is an option I do need. Darn for>>
loops!!>> > Thanks again. Will>>>>>>>>Craig Graham
wrote in message>news:3a826d9a@newsgroups.ni.com...>> Can't make out exactly
what you're on about but there shouldn't be a>> difference between the FOR
loop and the WHILE loop approach. In both cases>> to get an indicator to
update as the loop iterates you simply put the>> terminal of that indicator
inside the loop.>>>> The only difference I'm aware of between the way data
comes out of the two>> loops is that wires coming out of a FOR loop default
to auto-indexing, and>> wires coming out of a WHILE don't. Do when a wire
comes out of the for>loop>> it becomes an array, whilst the wire coming out
of the while loop remains>as>> the last data value the wire held. If this
is your problem, just pop up>with>> the right mouse button over the "blob"
where the wire leaves the loop and>> you'll see the "Enable auto-indexing"
option.>>>> Will wrote in message>> news:3a81cce4@newsgroups.ni.com...>>
>>> > I apologize... the subject should say from while loops. On a sidenote>to>>
> this. I have managed to do this with for loops. However, I cannot>abort>>
> my operation with for loops, and this is an option I do need. Darn for>>
loops!!>> > Thanks again. Will>>>>>>>>