Setting Limits on a real time XY graph

[krispiekream]

Hello,

I have this XY graph with some real data.

The limits were established prior to the WHITE lines have been drawn on the graph.

That is leaving me with all kinds of FAILURE because of the existing test.

Sometimes the motor is running too slow, grabbing too few of a data. Sometimes its too fast grabbing too much of data.

Can I set the limits somehow were its more dynamic? As in, when the end slope is starting to ZERO out when where THE LIMIT line ends?

Can someone guide me in the right direction.

I am using Labview 7.0

I can open with Labview 8.0

please help.

Thank you

[Wolfgang]

...you may want to ask an operator to move your post to the more appropriate LabVIEW forum

[krispiekream]

sorry. I didn't realize I posted in the wrong forum.

thanks!

[krispiekream]

 

Hello,

I have this XY graph with some real data.

The limits were established prior to the WHITE lines have been drawn on the graph.

That is leaving me with all kinds of FAILURE because of the existing test.

Sometimes the motor is running too slow, grabbing too few of a data. Sometimes its too fast grabbing too much of data.

Can I set the limits somehow were its more dynamic? As in, when the end slope is starting to ZERO out when where THE LIMIT line ends?

Can someone guide me in the right direction.

I am using Labview 7.0

I can open with Labview 8.0

please help.

Thank you

[Gregory]

Sure, create the ramp with say 170 points (instead of 220) currently.

Initialize array of length 50 with value of last point

Build array to combine them.

[krispiekream]

I am not sure if 170 is a good number or 220 is a good number.

for this set of values. 170 would be a good number. But in other runs, 220 would be best.

I don't want the function to have a set 170 or 220 value.

how would I implement the algorithm to set the set of points based on when the slope begins to ZERO out.

In this case.

around 70 and 280 would be good starting points?

[Gregory]

You can use the "Derivative x(t) " VI to see where the slope is greater than a certain threshold.

[Gregory]

Duplicate post here:

https://forums.ni.com/t5/LabVIEW/Setting-Limits-on-a-real-time-XY-graph/m-p/3758560#M1058547

[krispiekream]

I have tried using "Derivative x(t)"

but I think I used it wrong so it only show me index 0 as the first derivative of the array?

[Gregory]

It should return an array to you. If you just use index array, it will return the first value. If you reverse the array and then use index array, it will give you the last value.