Suggestion concerning probe attenuation in Tektronix 7000 Series Instrument Driver

[B_Spears]

Hello all, 

I'm attempting to program a Tektronix DPO 7254C Oscilloscope using LabVIEW 2011 with the Tektronix 7000 Series Instrument Driver:

http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=6566BC3787B433D2E0440003BA7CCD...

I'm using a P6139B voltage probe with the scope and I ran a few of the examples in LabVIEW that acquire an analog signal. I noticed that all the readings I was getting had a voltage amplitude 10x greater than the actual signal. Looking at the analog examples I saw that some of them multiply the probe attenuation value by the signal being read from the Read VI. Examples of this would be Tektronix 7000 Series Acquire Continuous Waveform.vi and Tektronix 7000 Series Acquire Waveform.vi.

It appears there are 2 problems with this:

1) I called up Tektronix tech (Tek?) support and they informed me that many voltage probes are "intelligent" and the scope can detect their attenuation and account for that internal to the scope so there is no need for the driver to manipulate the data. This is true on many of the later probes, but not true on the older ones. So it appears that the driver should perhaps inform the user of that, and allow the user to optionally multiply the data by the probe attenuation.

2) Even if the driver still needed to multiply the fetched data by the probe attenuation, it appears to do so inconsistently. For instance, there are several example programs that request a probe attenuation value from the front panel but then don't multiply the data by that value (as we saw those above 2 examples do). For example, Tektronix 7000 Series Acquire Multiple Waveforms.vi. It looks like the example programs should be updated for consistency.

Please let me know if there is anything else I should be taking into account. I've also posted about this driver here as I'm going to be doing a video tutorial for it: http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/Errors-1074000000-and-1073807339-with-Tektron...

Thank you!

Brian Spears

[margasan · Accepted solution]

Hello Brian,

From the readme file of the instrument driver under known issues:

To report issues or provide feedback about this instrument driver, please send an email to instrument.drivers@ni.com.

As this is a certified driver NI supported it but only R&D can modify it.

Regards,

Mart G.

[B_Spears]

Sure thing, just wanted to make sure I wasn't overlooking anything and/or get others' input before I head to R&D.

Thanks!

[margasan]

Hello Brian,

Thanks to you, we at NI really appreciate when customers take the time to report bugs in our products.

Warm Regards

Mart G