inconsistent x axis on waveform chart

[lflash]

I have isolated my problem to a simple vi consisting of only a
waveform chart and one numeric control to specify delta x. I am using
LV 5.1.1. I have used an attribute node to set x minimum to 0, x
maximum to 10, delta x to be entered by the user, and have turned
autoscaling off.

When I plot 2 random points, x maximum is inconsistent, and doesn't
stay at 10 when the vi is run several times in a row. Specifically,
the first time the vi is run with a new value for delta x, x maximum
changes. Then, the second time it is run, the max typically goes back
to 10. However, when run several times in a row, x max will
fluctuate. Specifically, I tried entering a delta x of 8. Mostly,
the min is 0, max is 10, and the line between the 2 r
andom points
plots from 0 to 8 along the x axis (good). However, every once in a
while, the x max will go to 8 and the line will take up the entire
plot. For my application, I need a fixed x axis.

This behavior is very strange, and will not allow me to program my
actual application correctly until I fully understand what is
happening. I would assume since Waveform Chart has these attributes
to set, I can still using the Waveform Chart, and don't have to
completely restructure my program to use another display (such as an
XY graph).

I can e-mail the simple vi I created, if requested.

Thanks in advance,
lflash

[Greg_McKaskle2]

....
> waveform chart and one numeric control to specify delta x. I am using
> LV 5.1.1. I have used an attribute node to set x minimum to 0, x
> maximum to 10, delta x to be entered by the user, and have turned

It sounds like you might want to use a waveform graph instead of a
waveform chart. The chart, like a chart recorder is built to scroll as
new data is plotted. It should be possible to set the chart to have a
fixed amount of time or indices on the X scale, but if/when the data
exceeds the max marker, the chart will change both min and max,
regardless of the autoscale settings. Autoscaling will change the
amount of data as well whereas a chart with autoscaling will scroll both
and always show the same amount of time/index.

Greg McKaskle

[Bauch@Berkeley]

Hello,
I have definately the same problem but one has to add that this problem depends on the charts history.
There is a correlation between x max (and x min) and the charts history.
Unfortunately I have not found a solution yet.