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Asynchronous calls in block mode - Labview

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Asynchronous calls in block mode - Labview

Postby carlosdmpereira » Mon Jun 30, 2014 2:39 pm

Hello,

I am having a problem using the Asynchronous calls in block mode.

When I try to change the function ps5000aGetValues to ps5000GetValuesAsync, labview crashes on running (attached to this email I send you a picture of the error)

Can anyone help me?

Cheers,
Carlos
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Labview Async function error.JPG
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Re: Asynchronous calls in block mode - Labview

Postby Hitesh » Mon Jun 30, 2014 3:22 pm

Hi Carlos,

LabVIEW is unable to handle C-style callback functions which probably why there is a crash.

Is it a PicoScope 5444B you are using, and have you selected the ps5000aGetValuesAsync function?

What is the reason for wishing to call the ps5000aGetValuesAsync function?

Regards,
Hitesh

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Re: Asynchronous calls in block mode - Labview

Postby Eva zhou » Thu Dec 04, 2014 3:56 am

Hi Hitesh,

In the programmer guide of ps5000Apg.en, when refer to ps5000aGetValues, it says, it is used to get the stored data from the "drive" after data collection has stopped. when refer to ps5000aGetValuesAsync, it says, it used to get the stored data from the "scope" after data collection has stoped. what is the difference between "from the driver" and "from the scope" ? I would like to read data from the scope buffer directly at the specified index and specified noOfsamples which is not the same as the sum of pretrigger and posttrigger.

Many Thanks
Eva
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Re: Asynchronous calls in block mode - Labview

Postby Hitesh » Thu Dec 04, 2014 2:27 pm

Hi Eva,

It looks as though there might be an error in the documentation.

The ps5000aGetValues function retrieves data from the oscilloscope while the ps5000aGetValuesAsync function retrieves data from the driver.

I would suggest using the ps5000aGetValues function as the ps5000aGetValuesAsync function requires the use of a callback function (which would require an update of the ps5000aWrap.dll).

The ps5000aGetValuesAsync function can be used for block data retrieval post-capture although it is really used to retrieve streaming data from the driver after data collection has stopped, returning only the pre- and post-trigger samples.

Regards,
Hitesh

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