High Precision Clock (Ni 6608); Using The Ocxo As The Source Counter; Using The Ocxo As The 10 Mhz Pxi Backplane Clock - National Instruments NI 660 Series User Manual

one counter of the TIO device. For continuous measurements, the transfer rate is the
maximum sustained rate for 30 seconds on one counter.

High Precision Clock (NI 6608)

The accuracy of your time measurement and pulse generation is determined
by the timing accuracy of your counter clock. The NI 6608 device has an
oven-controlled crystal oscillator (OCXO) that provides a highly stable
10 MHz clock that you can use as a GATE or SOURCE of a counter. You
can also use the OCXO as the PXI backplane clock. Modules phase locked
to the PXI backplane clock will acquire the same clock stability as the
NI 6608. For more information, refer to Info Codes at
search using keywords

Using the OCXO as the SOURCE Counter

Using the OCXO as the timebase source of the counter, you can route the
10 MHz clock to CtrnSource.

Using the OCXO as the 10 MHz PXI Backplane Clock

Your PXI chassis has a built-in 10 MHz backplane clock that is
independently routed to each peripheral slot. An independent buffer on the
chassis drives the clock signal to each peripheral slot with a skew of less
than 1 ns between slots. You can use this common reference clock signal to
synchronize multiple modules in a measurement or control system.
Use the OCXO 10 MHz clock to drive the PXI backplane clock so the
modules in the other slots can take advantage of the stable timebase.
Note On NI PXI-660x devices, the maximum timebase is phase locked to the PXI
backplane clock.
To use the OCXO 10 MHz clock as the PXI backplane clock, plug the
NI PXI-6608 device into Slot 2, or the slot immediately to the right of the
controller of the PXI chassis.
By default, NI-DAQ software drives the 10 MHz clock from the OCXO
onto the PXI CLK10 in pin so that the OCXO is used as the PXI backplane
clock. When the PXI chassis senses a clock on the PXI CLK10 in pin in
Slot 2, the chassis disables its internal clock, then uses the OCXO clock
instead, illustrated in Figure 2-7.
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Chapter 2
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Device Overview
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NI 660x User Manual