Trying to take oscilloscope voltage data

[NIquist]

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@sahurley wrote:

I was more referring to the tone of the responses.  People come to the forums because to be helped because they are either new to the software or stuck, not to be attacked.  I've only used a DAQ before so I'm not up on the VISA application and was just asking a simple question.

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The best way to do this is let LabVIEW do it for you.

1)  Attach your scope to the LabVIEW PC with USB and power it up.

2)  Help > Find Instrument Drivers...

3)  Click the Scan for Instruments and your scope should populate in the Connected Instruments tree.  Double click your scopes name in the tree and click Search>

4)  Click Install> on the next page.

5)  You're done!

Now you can open examples right from Instrument Driver Finder.  Plus, you have the instrument's palette added under Instrument I/O > Instr Drivers.  And, any examples provided for that device will be added to Help > Find Example... > Hardware IO > Instrument Drivers >  LabVIEW Plug & Play.

 EDIT:  BTW, You DO still have to specify the correct VISA device.  LabVIEW can't differentiate when there are multiple VISA devices connected.  You'll find your scope probably has a resource name like:  USB0::0x0957::0x1796::MY51450847::INSTR.  In this case the hex 957 means Agilent brand so your's will be Tektronix's code, the 1796 is a 2000-series DSO and the MY51450847 in my scope's serial number so you can always look on the back of the device to be sure you're talking to what you think you are.  That can come in VERY handy if you ever work with multiple banks of connected devices, trust me. 

[sahurley]

Thank you for your response. I actually installed the drivers already and have been trying to use the examples, but the time mechanism isn't working correctly. 

[billko]

"Time mechanism".  What is that?  It would help immensely if you could use some standardized terms so we don't have to guess what you mean.  Please try to be more precise with the wording when you try to explain what you are doing.

[billko]

The next question I have to ask is: Do you know how to take this measurement manually?  You will have to know that before you can take it automatically because the automatic way will mimic what you are doing manually.

[sahurley]

I don't know what you mean by taking it manually, the oscilloscope reads the voltage pulse and I just want to read and record the voltage pulses constantly (my system pulses every 1 second so I want to take measurements every 10 ms).  The timing mechanism is supposed to be the x-axis of the waveform chart, but it is not updating at all and just repeats the same time.

[RTSLVU]

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@sahurley wrote:

I don't know what you mean by taking it manually, the oscilloscope reads the voltage pulse and I just want to read and record the voltage pulses constantly (my system pulses every 1 second so I want to take measurements every 10 ms).  The timing mechanism is supposed to be the x-axis of the waveform chart, but it is not updating at all and just repeats the same time.

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By manually we mean do you know how to operate the scope to take the measurments you want.

[NIquist]

This may also depend on the Tektronix VIs and how they are set up.  I know when I run the examples for my Agilent scope it sets the timebase of the scope before it makes a measurment and transfers the data.  That way it knows how to set the LabVIEW graph x-axis.  The Tektronix examples may be different so as Bilko said, you will need to know how to set up your scope and read the parameters back into LabVIEW to ensure you are interpreting the data right.  For instance, one common gotcha is LabVIEW not knowing that the scope is using a 10:1 probe so it doesn't know to multiply the Y array X10 to compensate.

Definitely spend some quality time with your scope's manual and play around with the basic examples until you are comfortable that you are reading in LabVIEW what your scope is measuring in reality.

[NIquist]

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@sahurley wrote:

I don't know what you mean by taking it manually, the oscilloscope reads the voltage pulse and I just want to read and record the voltage pulses constantly (my system pulses every 1 second so I want to take measurements every 10 ms).  The timing mechanism is supposed to be the x-axis of the waveform chart, but it is not updating at all and just repeats the same time.

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I would not expect the scope to update the LabVIEW graph (or chart) X-axis in the way you seem to desire (still not sure if I understand what you're trying to accomplish).  The scope is sending a dT (time between points) and an array of Y ampitude values.  Unless you have your scope set up to trigger on one pulse and collect enough data to see the second pulse, you will not have any information available that tells you the frequency of the pulses.  There is no information coming from most scopes that provide a real time-stamp.  If you look at the timestamp sent from you scope in LabVIEW by unbundling the waveform you will probably see that it is alway set to the default (the "epoch" value).

Just so we are clear.  Exactly what are you trying read from your scope.  Time between pulses?

[billko]

This is going to be tough.  From what I can gather, you are pretty green with LabVIEW and you don't know much about your test equipment at all.  Sounds like either you bit off more than you can chew, or someone force-fed you with a firehose.

My best advice is to find someone who knows LabVIEW well and go over the Oscope manual and try to figure this out.  😞

[sahurley]

Basically what I want to do is read exactly what the oscilloscope is reading into LabVIEW so that I can save the data points.  The oscilloscope is reading  a voltage, which should spike once every second.  I want to see a. whether or not it is accomplishing this task and b. the real time match up versus the votlage pulse/spike.  So I pretty much just want an x column of time in seconds or ms and a y column of voltage values.