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The last sample point in the scope buffer has an invalid val

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The last sample point in the scope buffer has an invalid val

Postby bane » Wed Sep 21, 2011 9:22 am

Problem description:The last sample point in the scope buffer has an invalid value. Sometimes there are two last sampling points invalid.
The error occurs sporadically.

Scenario: Rapid Trigger Mode Capture (external trigger); number of captures =1; buffer size > 1000000

Is this a known bug or is there any possibility to verify the validity of sampling point?

Thanks in advance!
Bane


Used Scope Version:
PicoScope® 6 - PC-Oszilloskop-Software version: 6.5.84.14
Copyright © 1995-2011, Pico Technology Ltd

Modell: PicoScope 4227
Seriennummer: AR290/139
USB-Version: 2,0
Kalibrierungsdatum: Dienstag, 1. März 2011
Hardware version: 1
Driver: 1.1.0.168
bane
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Re: The last sample point in the scope buffer has an invalid

Postby Martyn » Mon Sep 26, 2011 11:54 am

As you are using Picoscope, rather than your own software, can you send the team at support@picotech.com a copy of the waveform when this occurs

Thank you
Martyn
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Re: The last sample point in the scope buffer has an invalid

Postby bane » Mon Sep 26, 2011 2:01 pm

no, I am using my own software.
May I send you ADC counts?

Regards,
Bane
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Re: The last sample point in the scope buffer has an invalid

Postby Martyn » Mon Sep 26, 2011 2:03 pm

Yes you can send ADC counts and we will take a look. Please include details of how you have set up the scope.
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Re: The last sample point in the scope buffer has an invalid

Postby bane » Thu Sep 29, 2011 8:05 am

Hi Martyn,

below you can find the last five indexes with the corresponding ADC values. The last two values (a and b buffer) are invalid.

This occurs sporadically.

As stated before I am using the rapid trigger mode with only one capture and with external trigger.
Both channels have 2V range (because of 1/10 probe). Channel A is CAN High (lowest voltage here is about 2700mV) and Channel B is CAN Low (lowest voltage here is about 1000mV).

Thanks.

aBuffer "index" 10416662 = "ADC Value" 4307 OK
bBuffer 10416662 = 4163 OK

aBuffer 10416663 = 4307 OK
bBuffer 10416663 = 4163 OK

aBuffer 10416664 = 4307 OK
bBuffer 10416664 = 4163 OK

aBuffer 10416665 = -565 NOK
bBuffer 10416665 = -1557 NOK

aBuffer 10416666 = -16929 NOK
bBuffer 10416666 = -17473 NOK
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Re: The last sample point in the scope buffer has an invalid

Postby Martyn » Mon Oct 03, 2011 8:48 am

Are these erroneous values part of the returned data set, or possibly values at the end of the buffer that are not populated by the driver ?

You may wish to discuss this in more detail directly with me at support@picotech.com
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