continuous scans USB-1608gx and USB-1808x

[jpavlich]

I would like to do a continuous analog input scan on 1 channel on the USB-1608gx-2AO and the USB-1808x units at their highest rates.

I would select the options CONTINOUS AND BACKGROUND.  What are the limits of the num_points in the a_in_scan() function(using python) for each of these devices?  As I understand it, I would read from the top half and then the bottom half of the memory buffer to collect the data continuously, right?

Thanks

 

 

 

[JRys]

Hello,

num_points is a 32-bit integer, so the value can be quite large. Size the buffer to hold one second of data, usually, this is big enough. Buffers need to be at least a multiple of the USB packet size * the number of channels. A buffer is allocated using win_buf_alloc. The USB-1808X will use win_buf_alloc32. The USB-1608GX-2AO packet is 256, the USB-1808X is 128. Take a look at the attached Python script.

Best regards,
John

a_in_scan_USB_1608G.txt