Hallo ! Has anyone an idea about the following: I want to use a waveform CHART (as opposed to graph) because I like the possibility of pushing single values into it. But I while my code pushes values into the chart, the X-axis (also the y axis) SHOULD be fixed. I set the autoscale OFF, but still the chart updates the X axis. In the attached code I set it to 0..15, but LabView changes it to 9..24. He keeps the difference max-min = 15 but not the exact values. I dont understand... what is the meaning of X autoscale-off, if not staying like I set it to be... What am I missing ? Is there a secret property I can set ? If not, is there a easy way of preventing the chart (only the chart) of updating at all, but still rembering the values I push in for a later update? The reason to do is, is to zoom in and zoom out with a given X_min & X_max. This is LabView2015 on Linux. Thanks in advance for any hint.

LabVIEW

turning off X axis autoscale in a CHART

Solved!

Solution

Accepted by topic author

@Seb77 wrote:
And yes, the property nodes... but unfortunately labview has no "set-this-way-at-compile-time"-property-node.

As we already said, LabVIEW is always compiled. If you want different behavior depending on if it is running in the development environment vs. as standalone executable (in run time engine), there is the conditional disable structure.

And if you insist on "property nodes" for some silly reason, there's one too:

@Seb77 wrote:

There is no such thing as a property node that sends a single value to a GRAPH, right ?

And there is also no way to manipulate (append to) the active plot that is within a GRAPH, right ?

A graph is a front panel indicator that has it's own memory space as well as a transfer buffer so the UI thread can update it independent of other code running in parallel. It display whatever is in the wire so all you need to do is change the wire value and the rest happens at leisure whenever the UI thread gets a chance. If you send millions of points to an auto-scaling graph with complicated lines and point styles, you are severely taxing the UI thread. While you can keep all data in a wire, you can easily decimate the data to be manageable for A: the user and B: the UI thread.

There are other creative ways, for example you could use an intensity graph of fixed size matched to the monitor pixels and replace array elements with data. Since the dimensions are constant, it is very easy on the memory manager. It can even be U8, because you can only have a max of 256 color anyway (ancient example). "Adding" points is reduced to replace one element with a new value.

LabVIEW Champion.