Using An Internal Source; Using An External Source; Routing Do Sample Clock To An Output Terminal - National Instruments NI 6221 User Manual

Chapter 6 Digital I/O
M Series User Manual

Using an Internal Source

To use do/SampleClock with an internal source, specify the signal source
and the polarity of the signal. The source can be any of the following
signals:
• AI Sample Clock
• AI Convert Clock
• AO Sample Clock
• Counter n Internal Output
• Frequency Output
• DI Change Detection Output
Several other internal signals can be routed to do/SampleClock through
RTSI. Refer to Device Routing in MAX in the NI-DAQmx Help or the
LabVIEW Help in version 8.0 or later for more information.

Using an External Source

You can route any of the following signals as do/SampleClock:
• PFI <0..15>
• RTSI <0..7>
• PXI_STAR
• Analog Comparison Event (an analog trigger)
You can generate samples on the rising or falling edge of do/SampleClock.
You must ensure that the time between two active edges of 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. The DAQ device reports an
overrun error to the host software.

Routing DO Sample Clock to an Output Terminal

You can route do/SampleClock out to any PFI terminal. The PFI circuitry
inverts the polarity of do/SampleClock before driving the PFI terminal.
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