double buffering

[Roulian]

Hello,

I want to set the buffer size to make double buffer. To size the buffer I use DAQmxSetBufferAttribute and the properties DAQmx_Buf_Input_Bufsize. But I have questions:
>>How is dimensionnized the double buffer? If I size it to 50 samps per chan, is the buffer size equal to 100 samps per chan to enable double-buffering or Is the buffer cut in two half-buffer part of 25 samps per chan ?
>> And if I dimensionize the buffer to 50 samps per chan, I think I'll have some OverWritten Error when I open many application on my computer(Is there some information with backlog). That's why I want to count this Error situations with Errcheck and I read status of error: is it a good method?

Can you help me?

Thanks

Julien

[pierreR]

Hello,
I think you used to program with Traditionnal NI-DAQ because you're talking about double buffering. however you should know that with NI-DAQmx the notion of double buffering is not really present with DAQmx. First you configure the buffer size on RAM using the nb of sample by channel of the DAQmxCfgTiming. That's configure the size of the buffer. After that when you use the DAQmxRead you can configure the number of elements you want to read or right on/in this buffer. that's why we don't really speak of double buffer. for more informations you should look at NI DAQmx help : Input buffer allocation.
Regards,