string constants, waveform charts and microsoft 
Author Message
 string constants, waveform charts and microsoft

Hello all-

I am running labview 5.1 on a Celeron 466 with NT 4.0 and a
PCI-GPIB-488.2 and PCI-MIO16XE-50 DAQ card.

Yesterday my NT machine crashed hard, so hard that the vi that was
running was altered when I finally got the machine running again (it
took me three tries and a sys admin guy to get it booted).

When I reloaded the vi and ran it I found that some of the string
constants within the program had been changed.  However, if you looked
with your eye, the acutal string hadn't changed, but the computer's
interpretation of that string was not the same as in the pre-crash days
(if determined this using probes and highlighted execution options).  I
found that all I had to do was delete the terminal and then create
another constant and enter the correct (read "same") string to make the
vi run properly.  Any plausible explanations (other than the usual
microsoft voodoo ?)  This happened in several, but not all, string
constant instances within the vi.

The other post-crash difference is the behavior of a particular waveform
chart.  This vi reads two DC voltages for each data point.  However, the
data points of interest are not always consectutive, meaning that we
often skip some points.  Example:  0,1,2,3,4,13,14,15,16,17,30,31,32.
We wish to plot these data points, *real time* on a point-by-point basis
as a function of data point.  Before the crash I simply bundled each
voltage into a cluster and sent the cluster to a  waveform chart and the
waveform chart displayed a scatter plot of data vs. point in the desired
manner, i.e. two voltage points for each data point where we collected
voltages and no voltage points where we didn't collect voltages (in the
above example points 5-12 and 18-29).  Now labview plots the data
consecutively (as a waveform chart is supposed to work).

It would seem as though before the crash either a) my waveform chart was
not working as spec-ed or b) I was coding it differently than I thought
I was and now things are behaving as they are supposed to.  In either
case, any suggestions on how to achieve my desired display?  Waveform
graphs will do what I want, but only once the whole data set has been
collected and I need this data real time.

For both situations all of my six backup copies of this vi behaved in
exactly the same way.

Thanks in advance.

-Mike

------------------------------------------
Michael D. Wojcik
Department of Chemistry
University of Idaho
Moscow ID  USA
83844-2343


------------------------------------------

Sent via Deja.com http://www.*-*-*.com/
Before you buy.



Tue, 09 Jul 2002 03:00:00 GMT  
 string constants, waveform charts and microsoft
Hi, I don't want to even think about what happened during the crashes, but I
can give you a way to plot only the points you want in real time.
You will have to use an XY graph, and keep track of your own x-values
(generate them using the iteration terminal of a loop, or number of seconds,
or whatever works for your application.)
Place the XY graph terminal INSIDE the while loop, and use two separate
shift registers - one shift register will maintain an array of x-values,
while the other will maintain an array of y-values. (use a third shift
register to maintain a second set of y-values as you mentioned).
I assume you have some criteria for points that you wish to plot, for
example, "all points with y greater than 0.5".  Use your specific criteria
to generate a boolean that can be wired to a case structure.  Wire the shift
registers so that they pass through the case structure.  In the true case,
use a build-array for the x-values and another build-array for the
y-values.  Each of these build-arrays should have two input terminals.  Wire
the left side of each shift register to the upper input of a build-array,
and change that upper input terminal  to array input.  Wire the new data
point coefficients (x to one build-array,  y to the other) to the lower
input of each build-array, and confirm that the lower inputs are element
inputs.  Thus in the true case, you append a coefficient to the 1-D array
that is riding around on the shift register.  In the false case, just wire
your shift registers straight through and the 1-D arrays remain unchanged.
Finally, use a bundle to assemble the x-coefficient and y-coefficient arrays
into the XY graph terminal.

This description is written for a single curve on an XY-plot; you'll have to
modify it (using that third shift register that I mentioned) for two
curves.  Hope this helps. Good luck!

Quote:

> Hello all-

> I am running Labview 5.1 on a Celeron 466 with NT 4.0 and a
> PCI-GPIB-488.2 and PCI-MIO16XE-50 DAQ card.

> Yesterday my NT machine crashed hard, so hard that the vi that was
> running was altered when I finally got the machine running again (it
> took me three tries and a sys admin guy to get it booted).

> When I reloaded the vi and ran it I found that some of the string
> constants within the program had been changed.  However, if you looked
> with your eye, the acutal string hadn't changed, but the computer's
> interpretation of that string was not the same as in the pre-crash days
> (if determined this using probes and highlighted execution options).  I
> found that all I had to do was delete the terminal and then create
> another constant and enter the correct (read "same") string to make the
> vi run properly.  Any plausible explanations (other than the usual
> microsoft voodoo ?)  This happened in several, but not all, string
> constant instances within the vi.

> The other post-crash difference is the behavior of a particular waveform
> chart.  This vi reads two DC voltages for each data point.  However, the
> data points of interest are not always consectutive, meaning that we
> often skip some points.  Example:  0,1,2,3,4,13,14,15,16,17,30,31,32.
> We wish to plot these data points, *real time* on a point-by-point basis
> as a function of data point.  Before the crash I simply bundled each
> voltage into a cluster and sent the cluster to a  waveform chart and the
> waveform chart displayed a scatter plot of data vs. point in the desired
> manner, i.e. two voltage points for each data point where we collected
> voltages and no voltage points where we didn't collect voltages (in the
> above example points 5-12 and 18-29).  Now labview plots the data
> consecutively (as a waveform chart is supposed to work).

> It would seem as though before the crash either a) my waveform chart was
> not working as spec-ed or b) I was coding it differently than I thought
> I was and now things are behaving as they are supposed to.  In either
> case, any suggestions on how to achieve my desired display?  Waveform
> graphs will do what I want, but only once the whole data set has been
> collected and I need this data real time.

> For both situations all of my six backup copies of this vi behaved in
> exactly the same way.

> Thanks in advance.

> -Mike

> ------------------------------------------
> Michael D. Wojcik
> Department of Chemistry
> University of Idaho
> Moscow ID  USA
> 83844-2343


> ------------------------------------------

> Sent via Deja.com http://www.deja.com/
> Before you buy.



Tue, 16 Jul 2002 03:00:00 GMT  
 
 [ 2 post ] 

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