Solution
Having a large first-in-first-out (FIFO) buffer is important for holding data during A/D conversions to ensure that no data is lost but due to current advancements in data transfer technologies, the focus has shifted to ensuring efficient data transfer between the onboard device FIFO buffer and system memory. This means that the buffer size on the device itself doesn't significantly affect the overall performance. The data transfer mechanism efficiently manages data flow, preventing overflow and underflow in the device's onboard device
buffer.
The data transfer method will vary depending on the device form factor.
Direct Memory Access (DMA) is the default transfer mechanism in PXI Express and PCI Express devices while
USB Signal Stream is the data transfer method for USB devices. The DAQmx driver handles this data transfer automatically but if required the
Programmed I/O is another method where the user is responsible for transferring the data, no host buffer is involved, instead, the data is directly read or written to the device buffer. Each DAQmx read or write call in the program initiates the transfer of data. Programmed I/O is typically used in software-timed (on-demand) operations.
While your code needs to manage
overflow and underflow errors on the host buffer properly by keeping it adequately filled during output tasks and reading from it regularly for input tasks, the good news is that these buffers in the system memory are significantly larger than the onboard FIFO buffer. You can trust that the reduced FIFO buffer size on the USB-6341 won't negatively impact your data acquisition tasks.