eric nelson

For completeness sake, here's an article on the difference between Value Property Node and Local Variable:

http://digital.ni.com/public.nsf/3efedde43...47?OpenDocument

Regards,

Khalid Ansari

The NI expantion was definitely a little over my head. My understanding is that if we are working within a single VI that local variables are quicker for the PC to handle than a value property node. Thanks!

Guys, I need some help learning how to use an "event structure". I've been playing around but I could use a formal introduction. I've found a bit of documentation on ni.com. Is there a good tutorial out there on ni.com?

Thanks,

Eric Nelson

I'm starting to understand adding graphing annotations. I was thrown by the fact that if the annotation list array is not populated before entering my main while loop I could not write to the list. Maybe I'm wrong about that but I've had success creating the annotaions in the annotion list array and then programatically changing them in the main program. I prefer this to creating them in the graph and then remembering where they are in the array. It's just my preference.

Thanks,

Eric Nelson

Nevermind the Labview example "Programmatically annotate a graph.vi" probably does what I want.

Guys, I need some help learning how to use an "event structure". I've been playing around but I could use a formal introduction. I've found a bit of documentation on ni.com. Is there a good tutorial out there on ni.com?

Thanks,

Eric Nelson

Is it possible to programatically position annotations or do they have to be manually inserted? I'd like to have an annotion placed after a test condition is met.

Nevermind the Labview example "Programmatically annotate a graph.vi" probably does what I want.

Eric: LabVIEW 8.0 has a new feature called Graph Annotations that will do what you want.

Is it possible to programatically position annotations or do they have to be manually inserted? I'd like to have an annotion placed after a test condition is met.

Add another plot to your chart, which plots 'NaN'. Add a point to this plot only when it satisfies your condition. This way special points will show up with a different marker.

You can add a different plot with a different marker to satisfy more than one condition (upper and lower limits for example).

There is an example under charts somewhere in your LV examples.

Neville.

Thanks, I found an example for a graph's cursor property node. There is an example for that. I haven't found the example you are eluding to. I think I understand what to try though.

Eric Nelson

It would be great if I could put markers into my chart to so the user that a condition had been met at that point in time as the vi is running. I was hoping to find a property node that would mark in a chart. I guess I could change the type of point displayed and then change it back to the default point on the next iteration. I think Labview should have this built in somewhere. Any ideas?

Thanks,

Eric Nelson

Hi. I have a newbie programming question. I need to build a test vi. The vi reads in two variables via USB DAQ card. The variables are strain and position. The test needs to function as follows: Set strain to 50 lbs then hold for 30s. Increase strain to 290 lbs then hold for 60s. The strains are set manually with a car jack so this is not a feedback control system. I only need to programatically check the that strain on the loadcell is within range and plot vs. time.

My question is, should I just build this thing in a single while loop? If so how should I keep track of the times at each strain?

Eric Nelson

Oops! My Bad!

You simply need the index array function, assuming the data has some reasonable distribution within the 2D array. See the attached VI.

Well that certainly works. Thanks!

On the Array Palette look for (or search for) the Decimate 1-D Array function. It does what you need by "dealing out" the elements of your big array into two or more smaller arrays.

It's the 2D array that I need to split. I need a 1D array of "column 0" and another 1D array of "column 1". It looks like the decimate function is only to split a 1D array into smaller subarrays. Am I missing the point?

Thanks!

I've been struggling with what should be very easy. I have a comma seperated value file from another instrument. I need to plot this data for analysis and prefer to use LabView over excel, sigmaplot, etc...

When I open the file with the read from spreadsheet file function I get a 2x10000 dimensional array. In order to use the graph XY function I need to separate the array to two different 1x10000 arrays and then bundle them together and send the bundle to the XY graphing funtion.

Can anyone help me either spit my 2D array into two 1D arrays or give me a different way to go about the problem?

Thanks