Electronics and Software
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DO Sample Clock Signal

  NI 6115/6120, NI 6122/6123, and NI 6132/6133 only

Use the DO Sample Clock (do/SampleClock) signal to update the DO pins with the next sample from the DO waveform generation FIFO. Because there is no dedicated internal clock for timed digital operations, you can use an external signal or one of several internal signals as the DO Sample Clock. You can correlate digital and analog samples in time by choosing the same signal as the source of the DO Sample Clock, AI Sample Clock, or DI Sample Clock.

If the DAQ device receives a do/SampleClock when the FIFO is empty, the DAQ device reports an underflow error to the host software.

Using an Internal Source

To use do/SampleClock with an internal source without making any external connections, specify the signal source and the polarity of the signal. The source can be one of the following signals:

  • AI Sample Clock
  • AO Sample Clock (NI 6115/6120 only)
  • Counter 0 Out

Program the DAQ device to update the DIO pins on the rising edge or falling edge of do/SampleClock.

Using an External Source

You can use a signal connected to any RTSI <0..6> pin as the source of do/SampleClock. You can generate samples on the rising or falling edge of do/SampleClock.

Any PFI line that can be routed to RTSI can also be used as the clock source. Refer to Device Routing in MAX in the NI-DAQmx Help for more information.

You must ensure that the time between two active edges of the do/SampleClock is not too short. If the time is too short, the DO waveform generation FIFO is not able to read the next sample fast enough.