LabVIEW
Why are charts and graphs so difficult?
Hi RTSLVU,
@RTSLVU wrote:
All I want to do is plot two values
What exactly is your problem?
(Isn't all this shown in the context help?)
@RTSLVU wrote:
on a chart or graph or whatever you want to call it.
You should call them as they are named in LabVIEW!
Helps you and us to understand your exact problem as there are differences between charts and graphs…
@RTSLVU wrote:
I don't want to go through all the trouble of making an X/Y chart and keeping all my chart history myself.
Like this?
@Bob_Schor wrote:
@Crossrulz -- that is so subversive, so clever, such a brilliant Nugget! Thanks for sharing!!
Your words are like an image that is not a snippet: worthless! You should thank me properly.
@crossrulz wrote:
@RTSLVU wrote:
I don't want to go through all the trouble of making an X/Y chart and keeping all my chart history myself.
Like this?
(Nugget: Sporatic Waveform Chart)
That's great, and a bit puzzling.
So the chart can do restricted* XY data, as long as X is time.
It would be useful [to me] if I could set a bunch of XY data at once as well. For instance, when a chart in a VI is multipurpose: showing real time data, and showing stored data. At real time, this trick will work.
I setting the chart's History the (only) way? This is array of waveforms, where each waveform has one point (in this example, there can be more points, but they will be dT apart).
*
A restriction is X has to increase, or nothing will show?
Another restriction is all channels have to have the same number of waveforms added.
Search LabVIEW like a graph! 
wiebe@CARYA wrote:
@crossrulz wrote:
@RTSLVU wrote:
I don't want to go through all the trouble of making an X/Y chart and keeping all my chart history myself.
Like this?
(Nugget: Sporatic Waveform Chart)
A restriction is X has to increase, or nothing will show?
While this is certainly a clever idea, it is a "trick" that works for a peculiar reason. Recall that the name of this Indicator is Waveform Chart. A Waveform has three components: t0, the starting X Value, dt, the constant spacing of all the unspecified, but computable X values, and Y, an array of all the Y Values. This "trick" lets you specify X (as t0), ignore dt (since you have only a single X), and replace the Y array with a single-element Array holding the single value of Y. I suppose you do get scrolling and other "Chart" attributes (I've never actually tried using this trick, though I applaud its cleverness).
Some time ago, I found a Blog Post (which I could probably find again) that described what I've come to call a "FlexiGraph", an XY Graph that had (by programmatic design) "Chart-like" scrolling properties. It also had the possibility of changing X scales during data collection, working by keeping several N-point copies of the plotted data in memory, updating all of them as new points arrived, and displaying the appropriately-scaled one as the User requests. It is a little tricky to program, but works like a charm, is fast and is memory-efficient.
Bob Schor
wiebe@CARYA wrote:A restriction is X has to increase, or nothing will show?
Another restriction is all channels have to have the same number of waveforms added.
Yep, all hell breaks loose when X goes backwards.
As far as the number of waveforms added, that only makes sense since you should only be writing to a chart from the terminal. This means you should have an array of waveforms already; a waveform for each channel. So I don't really consider this a restriction.
