Channel overrange on SW version 6.13.7.707

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RTFM@1984
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Channel overrange on SW version 6.13.7.707

Post by RTFM@1984 »

I am trying to measure the capacity of a battery pack by discharging it with a known resistor. For this I set a very large time/div (5000s/div) in order to able to capture about 10 hours. Unfortunately the software is unable to capture a voltage at such a large time/div setting. With shorter time/div setting (100ms/div) voltage looks good but with larger setting, the capturing does not work: It shows channel overrange. (See screenshot attached)

Normally during these 10 hours, voltage would drop from about 12.3v to 8v. So I choose a range of +/- 20v DC. At 8v the battery protection disconnects. In very some seldom cases after changing settings back and forth, I am able to capture without any issues. However most of the time I see the error.

My system: Thinkpad Carbon X1 Gen. 4, Ubuntu 18.04 LTS

Is there any workaround for this? Is this a known bug?

Any help would be appreciated.

Marc
Attachments
20190829.Channel_overrange.png

Martyn
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Re: Channel overrange on SW version 6.13.7.707

Post by Martyn »

Do you get the same overrange indication at 1s/div, where the trace will still be streaming ?

If you leave it running at 5000s/div does the trace become reasonable after a few minutes ?
Martyn
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RTFM@1984
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Re: Channel overrange on SW version 6.13.7.707

Post by RTFM@1984 »

> Do you get the same overrange indication at 1s/div, where the trace will still be streaming ?
I will need to try, at which speed it start to happen.

> If you leave it running at 5000s/div does the trace become reasonable after a few minutes ?
No it does not. I waited at least more than 10 minutes and the result was during all the 10 minutes the channel overrange. Looking like a massive vertical block of data. Not even the slightest trace of data I would expect.

RTFM@1984
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Re: Channel overrange on SW version 6.13.7.707

Post by RTFM@1984 »

I have tried further:

Above and including "100 s/div" picoscope cannot show the signal properly. Faster speeds (50 s/div and faster) work without issues.

Steps to reproduce:
1. Add power supply to the picoscope (6402D)
2. Connect a 12v battery to Channel 1. (+ to CH.1 and - to shield)
3. Start picoscope from the command line.
4. Change the voltage/div from "Auto" to "±20 V"
5. Change the time/div from "5 ms/div" to "100 s/div"

Observe that it is running. Now instead of the expected 12v voltage a widening vertical column is shown (see below), with the text "Channel overrange" and when zooming in, the vertical column looks like some kind of modulated waveform (see below):
Attachments
Screenshot from 2019-09-22 15-15-22.png
Screenshot from 2019-09-22 15-15-01.png

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