National Instruments NI PXIe-6672 - Manual (Page 22)

Chapter 3 Hardware Overview
© National Instruments Corporation 3-9 NI PXIe-6672 User Manual
clock; this feature must be explicitly enabled in software. The TCXO
output also can be routed out to the CLKOUT connector.
In addition to replacing the native backplane clock directly, the TCXO can
phase lock to an external frequency source. This operation is discussed in
detail in the
Using the PXI_CLK10 PLL section.
Routing Signals
The NI PXIe-6672 has versatile trigger routing capabilities. It can
route signals to and from the front panel, the PXI triggers, and the PXI star
triggers.
The CLKIN SMB input on the NI PXIe-6672 may be used for PXI_CLK10
replacement by either routing a 10 MHz signal directly from the CLKIN
input to PXI_CLK10_IN, or by using the CLKIN input as a phase lock
reference for the TCXO. When phase locking the TCXO to CLKIN,
CLKIN may be any multiple of 1 MHz to 105 MHz. In addition, CLKIN is
a valid source for PXI_Star.
The CLKOUT SMB on the NI PXIe-6672 may also be used to route the
TCXO, PXI_CLK10, or DDS Clock.