Y-Offsets

[hermannkleier]

I use a Rigol DS1102E. Could be that the issue cannot be observed on the DS1052.

I had a waveform recorded with "Y grid scale: 5.000e-01 V/div, Y shift: -1.500e-01 V". The information was transmitted in the wfm-file header and parsed by wfmutil.py correctly.

Edit: "Y shift" was -1.5 V on the DS1102E. Therefore, the value was parsed incorrectly. I missed that initially.

To convert to "real" voltages I use the formula (125 - $1) * 0.02 + 1.5), $1 being an unsigned byte value from the data array. The results match the displayed data on the scope.

In the contrary, the "wfmutil.py csv" values are shifted by -1.65V. I.e., instead of real 0V, the csv-file contains -1.65V.

Just a guess: Looks like "Y shift" is parsed too small (by a factor of 10) and considered with the wrong sign.

[mabl]

Hi Hermann,

thank you for the bug report. Did you shift the Y-Offset on the oscilloscope after you have stopped the measurement? This might be related to issue #2.

[hermannkleier]

Hi Matthias,

thank you for the prompt reply.

On Sun, 8 Sep 2013, Matthias Blaicher wrote:

Hi Hermann,

thank you for the bug report. Did you shift the Y-Offset after you have stopped the measurement? This might be related to issue #2.

no, I didn't. I had observed that the sequence of setups is critical
for the Rigol device. So I marked down the procedure. That way I got a
more detailed protocol (and the context) at

http://cross.kleier.selfhost.me/1wire_rigol.php

It is just a notepad, though.

Greetings,

Hermann

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Reply to this email directly or view it on GitHub:
#4 (comment)

[mabl]

Hi Hermann,

you were right... The shift calculation was wrong the whole time. I've fixed the problem and it should work for you now. I'm sorry for your troubles.

[hermannkleier]

Hi Matthias,

On Mon, 9 Sep 2013, Matthias Blaicher wrote:

thanks a lot for the quick fix.

Hi Hermann,

you were right... The shift calculation was wrong the whole
time. I've fixed the problem and it should work for you now. I'm
sorry for your troubles.

And thank you for sharing the code.

Hermann