Changing Reference Clock From PXI_CLK to OnBoardClock Takes Long on NI Vector Signal Transceivers (Ni 5644R/5645R/5646R)

Updated Mar 4, 2020

Reported In

Hardware

  • PXIe-5645
  • PXIe-5644
  • PXIe-5646

Driver

  • NI-RFSA
  • NI-RFSG

Issue Details

When I change the Reference Clock source from PXI_CLK to OnboardClock on my vector signal transceiver device (NI 5644R/5645R/5646R) it takes a long time (more than 10 seconds).

Solution

When using a vector signal transceiver device (NI 5644R/5645R/5646R), changing the Reference Clock source from PXI_CLK to OnBoardClk requires the hardware to disable and then re-enable the onboard Reference Clock. Disabling and re-enabling the onboard Reference Clock is necessary to provide the PXI Clk route enough isolation from the onboard clock. After being re-enabled, the clock requires ten seconds to reach stability.