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Digital Input and Output Benchmarks for USB-625X and Compact DAQ

Hardware: Multifunction DAQ (MIO)>>Portable>>USB-6251, Multifunction DAQ (MIO)>>M Series>>USB-6259

Problem:
What rates can I expect to obtain when using the USB-625X or CompactDAQ for Digital Operations?

Solution:
The data transfer rates of the devices tested are software timed, also called unstrobed or nonlatched, and do not require status and control signals so the transfer speeds are completely software/computer dependent. These rates may vary due to programming language and code efficiency, CPU utilization, transfer methods, and so on.

Below are the results of benchmark testing for the listed devices based on 10,000 updates. All tests were executed without software delays or data verification; generated values were toggled each iteration. 

To emphasis the difference between performance of the USB and PCI formats they are compared side-by-side.

CompactDAQ uses the same digital timing and the same USB technology for transfering data as the USB-625X devices, so their performance rates can be assumed to be the same.

Static Digital Input:
Data Format USB-625X PCI-625X
U32 (Port Format) 885 Hz 95000 Hz
1D Boolean Array 885 Hz 82000 Hz






Static Digital Output:
Data Format USB-625X PCI-625X
U32 (Port Format) 845 Hz 112000 Hz
1D Boolean Array 840 Hz 101000 Hz






Static Digital Input and Output:
Data Format USB-625X PCI-625X
U32 (Port Format) 435 Hz 30500 Hz
1D Boolean Array 430 Hz 28500 Hz






Test Computer:
Dell Optiplex GX280, Windows XP SP2, 1 GB RAM, Pentium 4 3.2 GHz

Related Links:
KnowledgeBase 3SJ70CX6: Software-Timed Digital I/O Benchmarks with DAQmx
KnowledgeBase 3TEC9UX6: USB-6501 Benchmarks with NI-DAQmx







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Report Date: 08/29/2006
Last Updated: 12/04/2008
Document ID: 40SDG946

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