Sample per channel and sample to read

Hello everybody
I am new in LABVIEW and I have some difficulties with something.
I don t know exactly what is the difference between the sample per channel et the sample to read. I believe knowing that the sample per channel is the size of the buffer which is more big than the sample rate but I don t know what is the sample to read.
I ve tested with different sample per channel and sample to read. Sometimes I have an error and sometimes know and I would like to know why. If you have any example for I understand better, it will be great.
I really need to understand this part for my project
Thank for your help
Romaric GIBERT
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Hi Roro,
As you mentioned, when acquiring continuous samples you can specify the sample buffer size by placing a value at the input "samples per channel" on the timing vi. The "number of samples per channel" input on the read vi which automatically names a control/constant with "samples to read" specifies the number of samples you wish to pull out of the buffer in one go when reading multiple (N) samples. This link may provide a bit more clarification. I have also attached a good example from the NI example finder which you may find useful to explore. I'm assuming you are using the DAQmx driver set so please let me know if this is not the case, but the same principles should apply either way.
This therefore means when sampling at a given rate, you need to ensure you are pulling data out in big enough 'chunks' to prevent the buffer from overflowing (which may well be causing the error you are seeing). Conversely if your sampling rate is slow and your read vi is having to wait for the number of samples to read you specified to be available, it may throw a timeout error. You can avoid this by either increasing your sampling rate, reducing your samples to read or increasing the timeout specified at the read vi input (-1 means it will wait indefinitely).
Let me know if this helps and how you get on.
All the best.
Paul
http://www.paulharris.engineering
Attachments:
Cont Acq&Graph Voltage-Int Clk.vi ‏27 KB

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Attachments:
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Solved!
Go to Solution.
Attachments:
2 Lock-In, 2 V Amp, Vd Amp - 090702(MTP).vi ‏100 KB
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Sample per channel and sample to read

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