Configuring Vertical Offset of LeCroy WaveRunner 64Xi using LabVIEW

[VPL]

I am using LeCroy WaveRunner 64Xi with its instrument driver downloaded from the NI website. When I run the example lcwave Acquire Multiple Waveforms.vi, the vertical offset becomes negative in the waveform I receive back from the oscilloscope. For example, when I enter the value vertical offset = 2.0 V, the oscilloscope receives it and displays the waveform properly. However, the vertical offset of the waveform returned to my pc becomes -2.0V. I tried to remove the negate value icon from the connector between lcwave Get Descriptor.vi block and Waveform Scale and Offset.vi block. It turns out that the vertical offset becomes doubled up, i.e. when I enter the value vertical offset = 1.0V, the waveform returned to my pc goes up by 2.0V. What could be the problem?

[alanjb]

Hi VPL,

Alan from LeCroy Tech Support here.  I'm not exactly sure what you are seeing... Can you restore the driver back to its original state, and then reproduce the problem and send me an email at alan.blankman@lecroy.com with images from both the scope and the lcwave Acquire Multiple Waveforms.vi front panel?   (You can back up your current version of the driver by renaming its folder first)

Two questions for you:

1) What is "Waveform Scale and Offset.vi"?  This is not part of the driver, and may be your problem...

2) What version of the driver are you using? See the readme file in the instr.lib/lcwave folder.  I'm using 2.1

The problem certainly isn't with Get Descriptor; the decoding of the waveform has been in place for many years without any reported problems.

Lastly, I ran the VI with the a 0 to 1V signals going into C1 and C2.  I find that the returned data matches what I see on the scope. (see the attached image)  (I tweaked the timebase and vertical scale constants that are on the block diagram of Acquire Multiple Waveforms.vi)

Best Regards,

Alan