Data Loss During Streaming 5442D

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Jimbo_1979
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Data Loss During Streaming 5442D

Post by Jimbo_1979 » Mon Oct 15, 2018 10:31 am

Dear All,

I am using the 5442D to acquire multiple channels from an array of sensors using Labview. The data is streamed at 640 ns (1.562MS/s) which is ~ a tenth of the maximum data rate. I can stream from either Channel A or B without any data loss. However, when I stream from both channels A and B I lose samples (~5-10%) which is not desirable. The buffer is set to maximum 0.5MS. Any assistance to resolve this would be appreciated.

Many Thanks

Martyn
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Re: Data Loss During Streaming 5442D

Post by Martyn » Mon Oct 15, 2018 11:41 am

The 5442D is capable of streaming on a single channel at ~156MS/s, so 100 times your rates. Therefore it would suggest that your streaming issues are not related to the devices capabilities, but more likely the way the streaming application has been constructed.

Please email your code to support@picotech.com and the team can take a look at this for you.
Martyn
Technical Support Manager

bennog
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Re: Data Loss During Streaming 5442D

Post by bennog » Mon Oct 15, 2018 3:02 pm

A buffer of 0.5MS is far to small.
If you sample at 1.5MS then only a small hickup from the HD will cause overrun.

Use a buffer (or multiple buffers) of at least 10 or 20 MS

Benno

Jimbo_1979
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Re: Data Loss During Streaming 5442D

Post by Jimbo_1979 » Thu Oct 18, 2018 9:50 am

Dear Martyn,

I will send my code over in a few minutes. I have been looking at the waveforms generated and it seems that there is no real data loss since the total count is correct. Instead the samples for each channel are mixing to some degree, which is indicating a problem in the wrapping I believe. The lost samples from one channel exactly match the samples gained in the other.

Regards,

James

Jimbo_1979
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Re: Data Loss During Streaming 5442D

Post by Jimbo_1979 » Thu Nov 22, 2018 4:34 pm

Dear all,

I am still to find a solution to this problem, so would really appreciate any assistance available. There is no problem with streaming from either channel A or B at four-five times the sampling rate shown, so do not believe it is a transfer issue. However in dual channel mode there is clearly a major problem. If anyone has a Labview program that works for any Pico ADC that would really help so I can compare it with my VI. Alternatively if anyone has any comments as the likely cause that would also be extremely useful.

Many thanks

James
Attachments
ADC_Channel A.png
ADC_Channel B.png
Duel_A_And_B.png

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