Determining the Clock Source of a PXIe-1092 Chassis

[bkarkar]

I am using a PXIe-1092 chassis with the timing and synchronization option. I want to override the chassis clock with the clock generated by the PXI-6683H module. I connected the clock out of the PXI-6683H module to the clock in of the chassis using an external cable. As mentioned in the knowledge page below, I set up the VI in the 'Single-Board Disciplining with the PXI-6683' section and verified with an oscilloscope that the PXI-6683 module is outputting a clock signal.

When I connect this output to the chassis, I am looking for a way to confirm whether the chassis is actually using this clock. In NI MAX, the clock source still appears as 'internal,' but I assume this might be normal since the chassis manual provides the table below, which states that the chassis is phase-locked. Therefore, it might still show 'internal' as the clock source.

Is there a way to determine which clock the chassis is currently using? There is a forum topic from 2012 mentioning that this is not possible, but I hope there have been updates or additional features since then.

NI Knowledge Page 

Old Topic 

[Henrik_Volkers]

If the 1092 chassis has no flag(property) to determin a valid clock source at his rear input ....

Idea: IIRR the PFI0 of the 6683 can measure frequency (simple count in a defined window, nothing fancy), so if you route internally or external via cable the backplane 10 Mhz to the 6683 PFI0 (50 Ohm termination 😉 ) you can measure/detect a clock difference ...   after 100s down to +-1 ppb.

Still only a indicator of difference, but maybe better than nothing. ( If a spare counter (or some ADC) is available that also could be used for a such a detection)