Time between CH1 and CH2's waveforms

[frnz]

I forgot to add this vi:

Frank

[Dennis_Knutson]

The function is reentrant so that is why you are seeing it as a clone. You would have to remove it from the vilib and save it as a new name and in a new location. Try the attached. It's one I originally used with 7.1.

[frnz]

Dennis,

I tried this vi in place of the one used on ch2, I left ch1 with the original.  I still get inconsistent data.  Also the "Find all Trigger Locations for 1 Channel.vi" provides an array instead of a single number of LV 8.5 version.

If is not possible to get consistent data with these vis, is there a way to analyze the data coming from the scope and find the "low" and "high" levels as I am dealing with a digital signal 0 to 5V?  Specifically I need to know the time that takes for the second waveform (ch2) to go high (including any bouncing of the signal).  Once I have this info a could send a command to the scope to set cursors at the beginning of the trigger and at end of 2nd waveform (ch2), then get delta value of these cursors location.  Thanks,

Frank

[frnz]

Dennis,

I have created a custom waveform using a PIC micro and I was able to check the accuracy of "Find all Trigger Locations for 1 Channel.vi," which it is accurate and consistent everytime.  But still can not get the total delay time including bouncing time.  I have made changes you recommended previously but still no luck:

"Yes you can. One way is to modify the trigger detection function so that it returns an array of points that meet the trigger condition. On the block diagram, you'll see a control called 'Max number of trigger points'. This control is hiddent so you'll first want this to be visible. You can then set this to some high number. The call library function node is already set to return an array of locations. Instead of indexing out element 0, just convert the entire array to relative times."

Could you please let me know what I am doing wrong or how to correct this issue.    Please see attached vis and picture. Thanks again,

Frank

[johnsold]

Frank,

Using the data in the VI you posted, I created a simple VI which locates the last rising edge in the waveform. You could modify it slightly to find the first falling edge of the other waveform and subtract to get the timing. This will not be very robust if there is significant noise near the threshold.

Lynn

[frnz]

Lynn,

Thanks very much for your susggestion and it works!

Also, the suggestion proposed by Dennis works now (I made a mistake in selecting time vs index). 

Thanks very much to both of you for your suggestions in this matter! 

Frank

[frnz]

Lynn,

Would you have any suggestions in regard to this vi (Switching time finder.vi)  as to be able to detect a straight line displayed on the scope, regardless of its amplitude?

Thanks,

Frank

[johnsold]

Frank,

I don't understand what you want. Is the straight line one of the waveforms? Is it horizontal, vertical or at some other angle? How much noise is on the signal? Other than random noise, do some of the data points deviate from a straight line?

What parameters of the line do you want to detect? Slope and intercept? End points? Other?

Lynn

[frnz]

Lynn,

The straight line is horizontal and for the most part clean, no points deviate from the straight line, except for random noise.  Basically the scope will read a steady DC voltage.  Thanks,

Frank

[frnz]

Lynn,

I made the following changes but is not working.  I need to detect relay's switching time as well as DC level when no relay is present.  Any suggestions?  Thanks,

Frank