Some questions about AnalogIn "Record" mode

April 27, 2021

Hi,

I have a few questions regarding the Record acquisition mode of the AnalogIn instrument as found on the Analog Discovery 2.

Is my understanding correct that in Record mode, I should not change the AnalogIn buffer size from its default value? I experimented with this a bit and it seems to give strange results. Is my suspicion correct that the option to set the buffer size is mainly intended for other acquisition modes like Single?
What type of underlying problems makes the libary report samples as corrupted and lost (as reported by the FDwfAnalogInStatusRecord call)? What is the difference?
Under some circumstances, the FDwfAnalogInStatusRecord will report a number of 'available' samples that is equal to the full buffer capacity, even at very low sample rates (e.g., this happens when the sampling frequency is set to 50 Hz, and the record duration to 100 ms; I quickly receive a whole bunch of "Triggered" states with 16384 available samples, followed by a single "Done" state with 16384 available samples, only the last 5 samples of the latter are actually relevant. Is this expected behavior, or perhaps a bug?

Any insight would be appreciated -- the deeper the better!

Best, Sidney

attila · April 27, 2021

In record mode the entire device buffer is used as FIFO. The buffer size setting is only used in the other capture modes.

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