Maximum Digital Output Frequency on USB-6xxx Devices

Updated Mar 12, 2019

Reported In


  • USB-6008
  • USB-6001
  • USB-6501
  • USB-6211


  • NI-DAQmx

Issue Details

I am using USB-6xxx device to output a digital square wave via DAQmx Digital Write. What is the maximum digital output frequency rate?


By using the DAQmx Digital Write function, the hardware USB 6XXX devices is using software timing for its digital output. Software-timed digital output is dependent on the timing of the operating system and code. If using a non-real-time operating system like Windows, there will be larger jitter and the timing will also be affected by other processes happening on the computer. For more information regarding software versus hardware timed, please refer to Timing, Hardware Versus Software.

Refer to Archived: Software-Timed Digital I/O Benchmarks with DAQmx for some benchmarks of some of our devices. If you would like faster or more deterministic results, contact NI Sales for other hardware or moving to a real-time system.

Additional Information

The USB-6xxx devices' digital outputs are not designed to output waveform signals in this manner, they are designed for static control of digital output lines.


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