Using the soft front panel to take a differential measurement.

[towleb1]

I have a PXI- 5152 digitizer and need to use the soft front panel to take a differential measurement. I found how to do this by programmatically, but cannot figure out how to do this  on the soft front panel. Can anyone help?

[CoffeeBreak]

Hi Towleb1,

From you second sentence in your question I assume you already found this resource, but just in case I wanted to provide you with a white paper called Differential Measurements Using High-Speed Digitizers. This is a fantastic resource that includes flowcharts and instructions for hardware self-calibration, probe compensation, gain and offset calibration, and actually taking the differential measurement itself.

As far as taking a differential measurement with the NI SCOPE Soft Front Panel, are you talking about taking a single differential measurement or are you talking about taking a differential measurement between two channels on the PXI-5152?

You mentioned that you found how to do this programmatically, but is there a reason you specifically want to use the NI SCOPE Soft Front Panel instead of LabVIEW?

[towleb1]

Hi Sam,

I want to take a differential measurement between two channels on the PXI-5152.

We want to use the front panel while troubleshooting and we need to measure the signals differentially.

We are unfortunately not using LabVIEW, we are using a different programming language to control the system, Python.

If it cannot be done using the front panel, I'll write a application to set it up in differential mode and take the measurements.

I wish we were using LabVIEW or CVI, or even visual studio.

[CoffeeBreak]

Towleb1,

Unfortunately at this time we are unable to take differential measurements with two channels in the NI SCOPE Soft Front Panel. The best we could do in this situation is take the measurement for each channel individually, stream the files to disk, and run a post processing on the data to generate the differential measurement. I assume this is probably what you wanted to avoid, but this is the best option with the functionality of the NI SCOPE Soft Front Panel. As you said, if we were using LabVIEW, LabWindows/CVI, or Visual Studio we could definitely implement this functionality. I hope this helps.

[Nathan-P]

Actually, there is a way to take a differential measurement using the Soft Front Panel, using the cursors.  Enable Cursors and Associate Cursor 0 with CH0, and Cursor 1 with CH1.  Then move the cursors to the position you want to measure, both of them.  You can view the delta between the cursors, it displays both the time delta between the two cursors, as well as the Amplitude delta, and the latter will show your differential measurement value.  

This will only work for a single measurement, so it won't make a waveform of differential measurements, but this is more than nothing.  

-Nathan  

[CoffeeBreak]

Nathan,

Thank you very much for your insight, I was unaware of this functionality with the cursors on the NI Scope Soft Front Panel. That is a very useful tool.

[Nathan-P]

I did forget one piece of important information, when setting up the Cursors, you will need to ensure that the Cursor Mode is set to "Lock to Plot".  Otherwise you will have to manually set both the X and Y position of the cursors.  But when its set to "Lock to Plot", the Y position will snap to the waveform, and you will not need to set it.  

I hope this helps!

-Nathan