clock disciplining in PXIe

[electronzoo]

Hi, I am having hassles with getting the clock disciplining software running on a PXIe system.  I've got a 1075 chassis, 6682H GPS card and a 6674T system timing card.  All devices appear in MAX.  GPS antenna is connected and locked.  I want to discipline the 6674T OXCO to GPS, but I just can't seem to get the clock disciplining software to do this.  I've tried using the clock disciplining app vi provided by NI and no luck.  The system timing and time source controls are greyed out.  I then tried to use the start servo, get servo status and stop servo vi's and I noticed that the start servo passes a void reference to the get servo status vi.  What could cause this?  The start servi vi recognises the 6682H in slot 2 and the 6674T in slot 10.  From what I can see in the 6682H documentation, there is no clock connections to the backplane, but the clock disciplining software manual says no external connections are neccessary.  How can the 6682H discipline the 6674T if there is no clock connection?  That would mean software, which surely is not a good idea with precise timing?

Glen

[MikhailK]

Hi Glen,

To make your system work you need to move your system timing module, NI PXIe-6674T to the PXIe system timing slot. I believe the system timing slot on PXIe-1075 is slot 10 (page 15 in the PXIe-1075 User Manual). The GPS timing and synchronization module, NI PXI-6682H can be moved to any other available peripheral slot. Keep in mind that unlike PXI-6682, PXI-6682H cannot be used as star trigger controller, so there is no point of placing it in slot 2. You do need that for your application anyway. 6682H will communicate with 6674T through PXI backplane. This will be accomplished through J1 and J2 connector pins of each module so indeed no external connections are necessary. Can you run your LabVIEW code again after you adjust your setup? Also what are the versions of LabVIEW and NI-Sync driver that you are using? Also refer to the following documents for more information:

Introduction to NI Clock Disciplining for PXI Express

Multi-Device PXI_Clk10Disciplining Software User Manual

GPS Timestamp Considerations for PXI and PXI Express