Chart x scale update problem

Question

LabVIEW  8.5.1
Sweep Chart Problem
The x scale values do not update until after the 2nd sweep.  The red line cursor gets to the end of the sweep and starts the next, but the scale numbers do not update until the next sweep starts.
It appears to be a problem with the chart, since it happens with any vi with a sweep chart.  I've used versions 6 through 7 for years and never seen this.  I've only recently moved to a new job with a new machine and version 8.5.1., so I'm not sure what to try.
I've included a simple example.
Thanks much,
JSC321
Attachments:
Chart Sweep Scale Update Problem.vi ‏32 KB

Answer 1

You have a typical race condition!
There is no data dependency between the property node and the while loop, so in your case the loop starts executing first and the property node starts slightly later, immediately erasing the first point. Execution order is not defined.
All you need to do is add a data dependency, e.g. as with the error cluster in the image. This forces the property node to complete before the loop is allowed to start.
(Execution order is enforced even if the wire value is not even used inside the loop )
Try it!
Message Edited by altenbach on 12-23-2008 11:08 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
HistoryRace.png ‏10 KB