Ni Scope

[toh]

Thanks. I did used the strip chart initially. However, it does not have the cursor feature like those in the XY waveform chart that allows me to measure the delta X.

Using the XY waveform chart, I, however, noted that the X scale does not seems to be real time. Thus, I need advise on how to go about it.

Just to provide some background. In my application, I am using channel 1 to measure impulse from one source and channel 2 to measure impulse from another source.  I want to measure the delta t between the impulse of this 2 channels.  

[Dennis_Knutson]

The x axis can be whatever you want it to be. If you wire an array of time values to it, it will be time. I don't quite understand how you are using the XY graph in the first place. Ther is no such thing as a XY waveform chart. It would seem to me, that you would want to use the waveform graph. You've got the abiltiy to use cursors and the x axis can represent in a much easier fashion. Why don't you post the code you have written? 

p.s. You can measure delta t between the two traces without the x axis displaying time. It can all be done automatically without manually using cursors.

[50ohmTerminator]

Hi Phooi,

I believe you can calculate the time between the pulses using the sampling rate and the number of samples between pulses. Ie. Say you are acquiring data at 1 MS/s and the first pulse occurs at the 10th sample and the second pulse occurs at the 110th sample. The time between them will be [1/(10^6)] * (110 -10) = 1/10000 = 0.1 ms.

This assumes that both channels started to acquire data at the same time.

Hope this helps.

Cheers
Malay

[toh]

If there is a way to auto measure, it will be good. Here is the code

[parthabe]

Your VI has too much unwanted code. I ve cleaned up those things.

Please try to avoid using Stacked Seq structures; if at all needed, use Flat Seq.

I cant figure out the usage of multiple Property nodes that re sitting parallel on the BD, they may race...

I think the measurement can be made automatically too, but I m not sure...

[parthabe]

Here you ve it in LV 7.0; I forgot earlier...

Even the Tab has been deleted.

What type of measurement you wish to happen (or take) automatically ?

[Dennis_Knutson]

Phooi,

I don't understand some of your comments. You have no XY Graph in the example you posted. There is just a waveform graph. You also have the waveform graph x axis set to 0 digits of precision.

Without seeing the actual waveforms that you are capturing, I can't say exactly how to perform an automatic measurement but you could try using a Basic Trigger Detection on each of the channels. You can set the location mode to time and then just subtract the trigger location of one from the other.

[Yardov]

Hello Phooi,

I think you are calling differently the type of graph you use but I think the main answer will depend on what you are trying to achieve.
First, thanks parthabe for cleaning the code and make it readable, scalable and maintainable.

Phooi, you are not configuring any horizontal settings and therefore will use the default which are not very good for placing a "read" on a loop. Now that I see you need to measure a delta t, let me assume a couple of things and correct me if I am wrong:
- You trigger from CH0 when the event you are looking for happened. For example, rising analog edge at some amplitude.
- CH1 will also start at that same time but the "event" of this signal happens x seconds later.

You can acquire only one time (one read) and configure your sampling rate, minimum record length and reference position such as you acquire for at least x seconds. There is a shipped example called "niscope EX configure acquisition.vi" that you can start playing with and once its working, you can reuse the code for your application.

Now, for timing you can do exactly what Malay suggest.  If you still want to use cursors, make sure your plot is not changing the X axis. For this, you will need to plot the graphs relative the trigger (from the example "niscope EX Multirecord.vi"):

Hope this helps,

Message Edited by Yardov on 09-05-2007 12:12 PM

[toh]

Thank you everyone for trying to help me. This is the first time I am playing with NI scope hoping to use it as a substitude for my oscilloscope. Sorry that I have confused everyone with waveform graph and XY graph.  I did not notice that initially.

Gerardo, I will take your advise and look at the shipped example to see if I can use it or modify to suit what I am trying to archieve.

I will check back at this forum again if I encountered further problem again.

Thanks a lot guys for the great respond.