Showing results for 
Search instead for 
Did you mean: 

PXIe-6674T sync to backplane

Go to solution


I'm trying to sync the PXIe-6674T oscillator to my PXIe-1095 backplane clock.  I don't know why NI can't keep their terminology consistent throughout the documentation.  The user manual never once mentions "oscillator" as a source.  At any rate, I tried to use the Route example to sync the clocks.  I connected "oscillator" to "PXI_CLK10_IN".  I don't get an error when doing so, but the "active" LED light doesn't turn on, which makes me think the backplane isn't deriving the PXI_CLK10 and PXIe_CLK100 from the PXIe-6674T.  My ultimate goal is to use the PXIe-CLK100 as the clock for my PXIe-7856R.

Thanks for any help.

0 Kudos
Message 1 of 5
Accepted by topic author Newtoit



To synchronize the backplane clock of chassis to the OCXO of PXI-6674T, all you need to do is route "Oscillator" to "PXI_Clk10_In" on the PXI-6674T. When a 10 MHz signal is connected to PXI_CLK10_IN, the PXI Express chassis is required to derive PXI_CLK10 and PXIe_CLK100 from this reference. The LED will remain off because the 10 MHz PLL on the PXIe-6674T is not in use. The active LED will only turn on if the that PLL is active. Also, the NI-Sync API supports multiple devices with different types of oscillators; some have an OCXO, a VCXO or a TCXO. The API uses oscillator because the underlining technology can vary from device to device.


I hope this helps,



0 Kudos
Message 2 of 5


So there's no indication whether the PXI_CLK10_IN is actively being used to derive the PXIe-CLK100 backplane clock?


0 Kudos
Message 3 of 5
Accepted by topic author Newtoit



There is no visible indicator on the chassis or device. But, you can check the status in NI MAX or query the status via the NI System Configuration API.


In NI MAX, navigate to the <system>/Devices and Interfaces/<chassis>. In the center frame under Settings, locate PXI Clock 10 Source. This displays the current source of the PXI_CLK10 reference clock. On PXI express chassis, PXIe_Clk100 is always derived from PXI_Clk10. So, this setting will also indicate the PXIe_Clk100 source as well.


You can programmatically check using the NI System Configuration and NI PXI Platform Services LabVIEW APIs. The property Devices & Chassis:Bus Specific:PXI Clk10 Source under System Hardware returns the source of the PXI_CLK10 reference clock. Note: You'll need the NI PXI Platform Services LabVIEW API installed to access this property in LabVIEW download link




0 Kudos
Message 4 of 5

It's working.  This has helped immensely!

0 Kudos
Message 5 of 5