Overlay chart with different Y scales

[JeffOverton]

I'm not sure if this is possible, but is there a manner in which to have several signals on a chart in overlay mode, but to give them all separate Y-scales?  What I'm envisioning is multiple signals displayed in an overlay, with an equivalent number of Y-axes (color coded to the signals probably) that all have separate scaling ability.  I'd prefer not to use transparent overlapping charts, because this will be around around 120 samples per second for all the signals, as well as controls and such, so I'd like to keep the book keeping as simple as possible for LabVIEW.

[JeffOverton]

OK, so I've discovered that ou can resize the plot legend and assign plots to different Y-axes, but is there any way to eliminate the now-empty plots?

Message Edited by JeffOverton on 06-13-2008 03:03 PM

[MikeS81]

Hi Jeff,
i can´t open your vi at the moment, but it sounds like you use the array to cluster function. If so, change the cluster size.

Hope it helps.
Mike

[JeffOverton]

No, it's a 2d array.  And either way, clusters and 2d arrays both let you move a plot to a different chart, but they don't let you eliminate the empty chart.

[Captain_Kirby]

Hi Jeff,

I took a look at your VI, and got some surprising results.

When I first opened it in either LabVIEW 8.2 or 8.5.1, I was able to observe the blank charts when run. However, when I modified the properties page, the problem disappeared. I could either deselect stack plots, and then reselect them, or I could reduce plots shown to 5, and then increase them back to 7.



In either case, when the properties were restored to the state you had them in originally, the problem was gone.



This led me to believe this was a bug, and so I tried to independently reproduce it. However, I have be absolutely unable to reproduce this behavior in either 8.2 or 8.5.1. No mater when or how I set the properties, the plots correctly display in their respective space. The empty plots are never seen.

I may not be correctly replicating some sort of setting on your machine, but at the moment, I cant confirm a bug nor offer anything except the above procedure as a solution. If there is any other information you can provide, it might help.




Message Edited by Captain Kirby on 06-16-2008 07:39 PM

[JeffOverton]

I agree that there is no bug, I'm just wondering if what I want is possible.  When you display as many plots as you have data signals coming in, there is one line per plot.  You can then assign individual lines to individual Y scales, leaving some plots empty.  However, if you try to eliminate these empty plots, all the lines that were originally assigned to them (and may now be assigned to arbitrary Y scales) are automatically put into the first plot.  So basically, if you have less plots than signals coming in, the extra signals always go to plot 1 instead of being assignable to any Y scale, and I want to be able to put signals on any Y scale without having the empty plots mentioned above.

[Captain_Kirby]

Hi Jeff,

I'm sorry I misunderstood your question, and I may still be confused, so please don't hesitate to correct me (you certainly wouldn't be the first.)

Are you looking for something like this?



In this chart, I have only five y scales, but have arbitrarily assigned the remaining plots to other y scales. This eliminates the two empty charts, and still has the remaining plots assigned to other scales. I did this by reducing the number of plots shown to five, and then changing the Y scale for plots five and six as depicted below.



Now, I may have this wrong again, so please clarify if I'm still out in left field.


Message Edited by Captain Kirby on 06-18-2008 07:44 PM

[JeffOverton]

Ok, I think I have everything set up properly, and it happened properly once, but I've been unable to repeat it.  It seems like the main problem is that changing the number of visible plots only affects how many are shown in the plot legend, not in the actual chart.  After I had it work once, I deleted the chart to see if I could recreate the success on a new one, and I can't figure out what I'm doing differently.  I've attached a VI with my settings on the chart, so maybe that will be a little more useful.

[Captain_Kirby]

Hi Jeff,

In your new example VI, you use a cluster to store the six numeric arrays. Because of this, the cluster defines the number of plots shown on the chart regardless of the value chosen in the properties. If you switch to just using a 2D array, you can reduce the number of plots shown, and then reassign the y axis of the remaining plots to one of the showing plots. That's how I achieved the result in my last post. The only way to change the number of plots shown when using a cluster as an input to the chart is to change the elements in the cluster, which would of course reduce the number of numeric arrays given to the chart.

So in order to achieve the result you want, I think your limited to just using a 2D array into the chart. And when I used this input method, I still had to be careful of the order I changed properties in. First you have to stack the plots, then reduce the number of plots shown, and finally, you can reassign the remaining plots to showing y-axes.


Message Edited by Captain Kirby on 06-20-2008 01:41 PM

[JeffOverton]

Ah, that got it. 

Thanks, it seems like I should have done the obvious thing and showed you what I was doing earlier and saved you a lot of time