Lock to 10 MHz PXI Backplane Clock

This setting locks the PXI-5600 downconverter internal reference to the PXI backplane. To use this option, connect the PXI 10 MHz I/O connector to the FREQ REF IN connector. This option is useful only when the onboard PXI clock is locked to a more accurate reference (such as a PXI-6608 or another PXI-5600) installed in slot 2.