waveform chart shifts first point by 50

[JayB]

I am plotting 20 points of data using the Waveform Chart. The data is sent to the chart as waveform;
t0 = 180, dt = 5, Y = my data points.
I am using the XScale.Range property to set the following:
Min = 180, Max = 280, Increment = 10, Minor = 5, Start = 180.
When I send the data to the chart it starts the X scale at 130 and the data at 180, the when the properties function is executed it shifts that chart to start at 180 (the correct format)
No matter what my start position (i.e. 200 instead of 180) the X scale always starts 50 positions below my t0 and then updates when the property node is run.
Why does LV extend the beginning of the X scale like that when you write data to the chart?

[Greg_McKaskle2]

> I am plotting 20 points of data using the Waveform Chart. The data is
> sent to the chart as waveform;
> t0 = 180, dt = 5, Y = my data points.
> I am using the XScale.Range property to set the following:
> Min = 180, Max = 280, Increment = 10, Minor = 5, Start = 180.
> When I send the data to the chart it starts the X scale at 130 and the
> data at 180, the when the properties function is executed it shifts
> that chart to start at 180 (the correct format)
> No matter what my start position (i.e. 200 instead of 180) the X scale
> always starts 50 positions below my t0 and then updates when the
> property node is run.
> Why does LV extend the beginning of the X scale like that when you
> write data to the chart?

I think the thing that is happening is that
your X scale is initially
set to show more data than you are going to plot in one update, which is
typical. If you are plotting one seconds data, each second, it is
common for the chart to be set to show ten or fifteen seconds of
history. If it is set for ten seconds, after the first update, the
chart will have only 10% data and will have 90% empty space, either
after it or before it.

If your intent is to view all of the data of an update, and only that
data, no history, you likely want to switch from a chart to a graph.
With that, I think you will find that the autoscale does what you want.
If not, the same X Scale Range property is available.

Greg McKaskle