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Maximum Number of Points in the cbAoutScan call


Fergal Cassidy
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int cbAOutScan(int BoardNum, int LowChan, int HighChan, long NumPoints, long *Rate, int Range, int MemHandle, int Options)

 

Using the cbAOutScan call for the USB 1808 and assuming a 100kHZ output rate, channels 0 to 1 and CONTINUOUS option what  is the maximum number of NumPoints that can be loaded.

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Hello,

The count variable is a Long number type, so it is a signed 32 bit number. A negative buffer size make no sense, so the maximum is half that or 2,147,483,647. But ultimately, it will depend on what your system will allow. 

John

 

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Hi Fergal,

You are correct, the buffer is maintained in the driver. This allows us to use a small hardware buffer and this is true for most of our devices.

For many applications, a large buffer is unnecessary because it can be update during operation. In the following example, the buffer is  update while running. It writes the same data (for simplicity) over-n-over - first updating the low half then the upper half of the buffer depending on the index location.

https://kb.mccdaq.com/KnowledgebaseArticle50719.aspx

Regards,

John

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