Waveform cursors and "data gates"

[PaulG.]

I have a waveform graph and want to capture certain periods of the waveform. I want a cursor to appear as a line that is adjustable in length, position and level, much like data gates used in ultrasonic A-Scan applications. I have been doing this in the past by superimposing a picture drawing lines over the graph, but I think data gates using cursors would be easier to manage and simplify things. Does anyone know how to make a cursor appear as a line that can be adjusted for length and position on the graph? And it would be even better if it were adjustable with a touch screen or with the mouse.

Paul

7.1/XP

[devchander]

Hi Paul,

Click on graph and select visible items->cursor legend

On the cursor legend, go to cursor window and "Left" click with your mouse.

In the pop down menu, select cursor style as either horizontal or vertical line.

Look at attached VI

Regards

Dev

[PaulG.]

I'm familiar with the cursor features, but I want to connect two cursors and draw a line between them. The cursors must be locked to each other horizontally, and when I adjust the level of one the other will move with it. Maybe I can draw another plot connecting the two?

Paul

[AESulzer]

Paul,

There is no one, built-in function in LabVIEW that allows you to do this behavior, but you can easily code it yourself. What you have to do is detect when one of the two cursors is moved and then move the other cursor with it. If you want to also graph a line between the two cursors, you can do that, too, just by plotting it like any other plot.

Coding this behavior is a breeze in LabVIEW 8 because there is now an acutal "Cursor Move" event; I have attached a LabVIEW 8 VI that demonstrates how to implement what you are talking about. In LabVIEW 7.1 and older, this is a little more difficult because there is no "Cursor Move" event, but there is an old post that discusses possible workarounds.

Kind Regards,