orthonormal scale

[Kentmey]

Hi,

I've got a problem with plotting data with Labview. I am plotting Nyquist charts, but I was not very happy of the nyquist vi on labVIEW. Therefore, I was wondering how to plot the two axis in orthonormal scale (as shown on the picture). It is not something labview does automatically, and it is rather annoying, and therefore I was wondering whether one of you might have a suggestion for this.

Let me know

Kentmey

[altenbach]

I am not aware of a nyquest.vi in plain LabVIEW. Are you talking about a toolkit?

I am not sure what is specifically important to you in the picture you are showing, but a plain XY graph can probably do that. You can add lines, text, decorations, etc. using the "Plot images" properties. (example)

[Kentmey]

Well, my point on the picture was that the lenght between 0 and 1 is the same on the x and y axis, something that is not done automatically when plotting data with labview.

Does it make it more clear now? this is called orthonormal scale.

Kentmey

[altenbach]

Well, you should (1) turn off autoscaling, (2) right-click...advanced... disable "autoadjust scales", then (3) size the graph area with equal number of pixels in each dimension.

[johnsold]

Kentmey,

You can use property nodes to set the plot area, the scales, and other plot parameters as well as the plane type (to set it to Nyquist).  I suspect that this is new enough and a relatively low percentage of users of XY Graphs that NI decided not to tie several properties together when you select the Nyquist plane or any of the other specialty graphs.

I suggest you customize a graph to get all the parameters set the way you want and make a strict typedef.  Then use that whenever you want a Nyquist plot.

Lynn

[elset191]

---

@johnsold wrote:

Kentmey,

You can use property nodes to set the plot area, the scales, and other plot parameters as well as the plane type (to set it to Nyquist).  I suspect that this is new enough and a relatively low percentage of users of XY Graphs that NI decided not to tie several properties together when you select the Nyquist plane or any of the other specialty graphs.

I suggest you customize a graph to get all the parameters set the way you want and make a strict typedef.  Then use that whenever you want a Nyquist plot.

Lynn

---

[Kentmey]

Now we are talking. will give it a try tomorrow & let you know how that goes.
Thanks 🙂

[Kentmey]

@else191 : tried that already, just adds axis, and doesn't actually makes what i want ( described earlier in discussion)

[Kentmey]

@altenbach : but wouldn't this keep the same scale during the plotting? or will this keep updating?

[johnsold]

Kentmey,

If you want the scales to change as your data changes but also to retain equal scales for both axes, you will need to do the work yourself.  Calculate the range you want and set the scales with property nodes. You may need to use Defer Front Panel Updates while making the changes.

There are many properties for graphs, their scales and axes, plot sizes, and so on.  Many of these interact in complicated ways.  Decide what you want the graph to do under various conditions and then write a trial VI which allows you to exercise those conditions and try various properties until you get it to do what you want.

Lynn