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Dropout gaps in streaming samples by console application

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Dropout gaps in streaming samples by console application

Postby thsc » Wed Jan 18, 2017 9:58 am

Hello,
I build a console application for a 6404D picoscope to sample data to my pc disk.
For first tests I took 1 million samples but sometimes the collected data has some dropout gaps in the curve. I build the console application by the Eclipse Cpp Neon IDE with the code Pico supported. My further target is to collect data for a time of 20 seconds at a sample rate of 50 MSPS.
During different test I found out that Picoscope did an auto stop before reaching the given number of samples to stop the streaming.
Is there a known topic in the hardware or did I make an error with my buffer handling?

I attached pictures of the signal curve O.K. and NotO.K. and also the c-code I used to build the application.
picoscope_stream_nok.png
signal not ok

picoscope_stream_ok.png
signal ok

ps6000con.c
c code for console application
(73.73 KiB) Downloaded 32 times



Best regards

Thomas Schaefer
NDT Global
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Re: Dropout gaps in streaming samples by console application

Postby Hitesh » Wed Jan 18, 2017 1:38 pm

Hi Thomas,

Which version of the ps6000.dll are you using?

Is the device connected to a USB 2.0 port or USB 3.0 port?

The overview buffer size of 20e6 looks quite large - try reducing this value to something like 1 to 5 MS. This buffer only needs to be slightly larger than the time it takes to execute each iteration of the loop.

When you refer to a problem with the auto stop, how many samples are being collected up to the point where the auto stop flag is set in the callback?

Regards,
Hitesh

Technical Support Engineer
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Re: Dropout gaps in streaming samples by console application

Postby thsc » Thu Jan 19, 2017 8:05 am

Hello Hitesh,

thank you for your hint's.

Here are some information to my setup:
- The Version of my SDK is 10.6.10.22
- The device is connected via UBB3.0
- In case of auto stop the number of samples is sometimes 0 and often between 100k to 400k samples

I tried to reduce the buffer size but this does not eliminate the problem.

Which size of post trigger samples will be useful for manually stopped streaming over a time of circa 20 seconds?

Best regards

Thomas Schaefer
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Re: Dropout gaps in streaming samples by console application

Postby Hitesh » Thu Jan 19, 2017 12:22 pm

Hi Thomas,

Try testing the application using the ps6000.dll and picoipp.dll files from the PicoScope 6.12.5 installation directory as they are more recent. These are 32-bit drivers, so if you require 64-bit versions, please respond on your existing support ticket and I can make them available for download.

Regards,
Hitesh

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